    [Senate Hearing 108-359]
    [From the U.S. Government Publishing Office]

                                                            S. Hrg. 108-359

    CLIMATE HISTORY AND THE SCIENCE UNDERLYING FATE, TRANSPORT, AND HEALTH
                          EFFECTS OF MERCURY EMISSIONS

    =======================================================================

                                    HEARING

                                   BEFORE THE

                                  COMMITTEE ON
                          ENVIRONMENT AND PUBLIC WORKS
                              UNITED STATES SENATE

                          ONE HUNDRED EIGHTH CONGRESS

                                 FIRST SESSION

                                   __________

                                 JULY 29, 2003

                                   __________

      Printed for the use of the Committee on Environment and Public Works

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    ____________________________________________________________________________
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                   COMMITTEE ON ENVIRONMENT AND PUBLIC WORKS

                          one hundred eighth congress
                                 first session

                      JAMES M. INHOFE, Oklahoma, Chairman
    JOHN W. WARNER, Virginia             JAMES M. JEFFORDS, Vermont
    CHRISTOPHER S. BOND, Missouri        MAX BAUCUS, Montana
    GEORGE V. VOINOVICH, Ohio            HARRY REID, Nevada
    MICHAEL D. CRAPO, Idaho              BOB GRAHAM, Florida
    LINCOLN CHAFEE, Rhode Island         JOSEPH I. LIEBERMAN, Connecticut
    JOHN CORNYN, Texas                   BARBARA BOXER, California
    LISA MURKOWSKI, Alaska               RON WYDEN, Oregon
    CRAIG THOMAS, Wyoming                THOMAS R. CARPER, Delaware
    WAYNE ALLARD, Colorado               HILLARY RODHAM CLINTON, New York

                    Andrew Wheeler, Majority Staff Director
                     Ken Connolly, Minority Staff Director

                                      (ii)

                                C O N T E N T S

                                  ----------
                                                                       Page

                                 JULY 29, 2003
                               OPENING STATEMENTS

    Allard, Hon. Wayne, U.S. Senator from the State of Colorado,
      prepared statement.............................................    11
    Cornyn, Hon. Jon, U.S. Senator from the State of Texas, prepared
      statement......................................................    58
    Inhofe, Hon. James M., U.S. Senator from the State of Oklahoma...     1
    Jeffords, Hon. James M., U.S. Senator from the State of Vermont,
      prepared statement.............................................     7
    Voinovich, Hon. George V., U.S. Senator from the State of Ohio...     3

                                   WITNESSES

    Legates, David R., director, Center for Climatic Research,
      University of Delaware.........................................    12
        Prepared statement...........................................   209
    Levin, Leonard, program manager, Electric Power Research
      Institute......................................................    40
        Prepared statement...........................................   211
    Mann, Michael E., assistant professor, University of Virginia,
      Department of Environmental Sciences...........................     9
        Prepared statement...........................................   173
        Responses to additional questions from:
            Senator Inhofe...........................................   178
            Senator Jeffords.........................................   194
    Myers, Gary, professor of Neurology and Pediatrics, Department of
      Neurology, University of Rochester Medical Center..............    44
        Prepared statement...........................................   299
    Rice, Deborah C., toxicologist, Bureau of Remediation and Waste
      Management, Maine Department of Environmental Protection.......    42
        Prepared statement...........................................   283
        Responses to additional questions from Senator Jeffords......   284
    Soon, Willie, astrophysicist, Harvard-Smithsonian Center for
      Astrophysics...................................................     6
        Prepared statement...........................................    58
        Responses to additional questions from Senator Jeffords......   155

                              ADDITIONAL MATERIAL

    Articles:
        Climate Research, Vol. 23:89-110, 2003, Proxy Climatic and
          Environmental Changes of the Past 1000 years..............127-148
        Energy & Environment Vol. 14, Nos. 2 and 3, 2003,
          Reconstructing Climatic and Environmental Changes of the
          Past 1000 Years: A Reappraisal.............................60-126
        Geophysical Research Letters, Vol. 31, Estimation and
          Representation of Long-term (>40 year) Trends of Northern-
          Hemisphere-gridded Surface Temperature: A Note of Caution.149-154
        Original Contributions, Effects of Prenatal and Postnatal
          Methylmercury Exposure From Fish Consumption on
          Neurodevelopment..........................................302-308
        Personal Health, Tip the Scale in Favor of Fish: The
          Healthful Benefits Await...................................   321
        Risk Analysis, Vol. 23, No. 1, 2003, Methods and Rationale
          for Derivation of a Reference Dose for Methylmercury by the
          U.S. EPA..................................................290-298
        The Atlanta Journal-Constitution, June 6, 2003, Clear Skies
          Mercury Curb Put in Doubt..................................   317
        The Lancet, Prenatal Methylmercury Exposure from Ocean Fish
          Consumption in the Seychelles Child Development Study.....309-316
        The New York Times, July 29, 2003, Does Mercury Matter?
          Experts Debate the Big Fish Question.......................   319
        The Philadelphia Inquirer, March 7, 2003, Mercury Rising.....   318
    Chart, National Mean Mercury Concentration in Tissues of Selected
      Fish Species (all sample types)................................   289
    Letter, to Senator Inhofe, from John Christy.....................   323
    Report, EPRI, May 2003, A Framework for Assessing the Cost-
      Effectiveness of Electric Power Sector Mercury Control Policie217-282

    CLIMATE HISTORY AND THE SCIENCE UNDERLYING FATE, TRANSPORT, AND HEALTH
                          EFFECTS OF MERCURY EMISSIONS

                                  ----------

                             TUESDAY, JULY 29, 2003

                                   U.S. Senate,
             Committee on Environment and Public Works,
                                                        Washington, DC.
        The committee met, pursuant to notice, at 9 o'clock a.m. in
    room 406, Senate Dirksen Building, Hon. James M. Inhofe
    (chairman of the committee) presiding.
        Present: Senators Inhofe, Allard, Carper, Clinton, Cornyn,
    Jeffords, Thomas and Voinovich.

     OPENING STATEMENT OF HON. JAMES M. INHOFE, U.S. SENATOR FROM
                         THE STATE OF OKLAHOMA

        Senator Inhofe. The meeting will come to order.
        We have a policy that we announced when I became chairman
    of the committee that we will start on time, whether anyone is
    here or not here, members, witnesses or others. So I appreciate
    all of you being punctual in spite of the fact that the
    Senators are not.
        One of my primary objectives as chairman of the committee
    is to improve the way in which science is used. I think that
    when I became chairman of this committee, I announced three
    very outrageous things that we were going to do in this
    committee that have not been done before. No. 1, we are going
    to try to base our decisions, things that we do, on sound
    science. No. 2, we are going to be looking at the costs of some
    of these regulations, some of these policies that we have, and
    determine what they are going to be. And No. 3, we are going to
    try to reprogram the attitudes of the bureaucracy so that they
    are here not to rule, but to serve.
        Good public policy decisions depend on what is real or
    probable, not simply on what serves our respective political
    agendas. When science is debated openly and honestly, public
    policy can be debated on firmer grounds. Scientific inquiry
    cannot be censored. Scientific debate must be open. It must be
    unbiased. It must stress facts rather than political agendas.
        Before us today, we have two researchers who have published
    what I consider to be a credible, well-documented, and
    scientifically defensible study examining the history of
    climate change. Furthermore, these are top fields of inquiry in
    the Nation's energy environment debate and really the entire
    world's energy environment debate. We can all agree that the
    implications of this science are global, not only in terms of
    the environmental impacts, but also energy impacts, global
    trade impacts, and quite frankly, no less than global
    governance impacts.
        We could also all agree that as a result of the import and
    impact of these issues, it is absolutely crucial that we get
    this science right. False or incomplete or misconstrued data
    are simply not an acceptable basis for policymaking decisions
    in which the Congress of the United States is involved. Such
    data would violate the Data Quality Act, which we passed on a
    bipartisan basis here in the Senate and which we have
    bipartisanly embraced. If we need more data to satisfy our
    standards, then so be it.
        This Administration is prepared to do so in an aggressive
    strategy that the climate change strategic plan outlines. The
    1000-year climate study that the Harvard-Smithsonian Center for
    Astrophysics has compiled is a powerful new work of science. It
    has received much attention, and rightfully so. I would add at
    this time, it did not receive much attention from some of the
    liberal media who just did not want to believe that any of the
    facts that were disclosed were accurate.
        I think the same can be said in terms of work that has
    recently received attention of the hockey stick study. In many
    important ways, the Harvard-Smithsonian Center's work shifts
    the paradigm away from the previous hockey stick study. The
    powerful new findings of this most comprehensive study shiver
    the timbers of the adrift Chicken Little crowd.
        I look forward to determining whose data is most
    comprehensive, uses the most proxies, maintains the regional
    effects, avoids losing specificity through averaging
    statistics, considers more studies, and most accurately
    reflects the realities of the Little Ice Age, reflects the
    realities of the Medieval Warming Period, and more.
        Mercury presents a different set of issues. That would be
    our second panel. It is well-established that high levels of
    exposure to methyl-mercury before birth can lead to neuro-
    development problems. But what about mercury consumed through
    fish, the most common form of prenatal exposure? Mercury makes
    its way into fish through various ways, but primarily though
    deposition from air emissions, with 80 percent of emissions
    deposited either regionally or globally, not locally. Global
    mercury emissions are about 5,000 tons a year. About half of
    those are man-made emissions.
        In the United States, a little more than 100 tons are
    emitted from non-power plant sources. Industry is making great
    strides in reducing these emissions. I would like to submit for
    the record this EPA document available on their Web site which
    indicates that when rules now on the books are fully
    implemented at non-power plant, nationwide emissions will be
    cut by nearly 50 percent. Power plants emit about 50 tons of
    mercury annually, about 1 percent of the worldwide emissions.
        In setting policy, key questions need to be answered, such
    as how would controls change this deposition; what portion of
    mercury exposure can not be controlled; and what are the health
    impacts of prenatal exposure. We will hear testimony today that
    indicates any changes to mercury exposure in fish would be
    minimal under even the most stringent proposal to regulate
    mercury. Today, we will also hear testimony that the most
    recent and comprehensive study to date found no evidence that
    prenatal mercury exposure from ocean fish presents a
    neurological risk.
        So we have diverse opinions that will be discussed today,
    and that is the reason for this hearing, to wade through that
    so that those on the panel that will be making policy decisions
    will understand. I think it is no secret that we are not
    scientists up here, so we look at things logically.
        With that, I would recognize one of my colleagues here that
    I have a great deal of respect for. Senator Voinovich and I
    started out together as we were mayors of cities almost 25
    years ago. I consider him to be one of the real experts in the
    area of air. In fact, I can remember calling him in as an
    expert when he was Governor of Ohio and we were holding these
    hearings and I was chairman at that time of the Clean Air
    Subcommittee. I would recognize Senator Voinovich for any
    comments he would like to make or opening statements.

      OPENING STATEMENT OF HON. GEORGE V. VOINOVICH, U.S. SENATOR
                         FROM THE STATE OF OHIO

        Senator Voinovich. Thank you, Mr. Chairman.
        I want to congratulate you for the very comprehensive floor
    speech that you gave yesterday on the issue of climate change.
        Senator Inhofe. I guess I should apologize. It was 12,000
    words and I know you were anxious to get some floor time, so I
    appreciate your patience.
        Senator Voinovich. Your words were much more scientifically
    based than mine.
        [Laughter.]
        Senator Voinovich. The two issues that we are going to
    explore at the hearing today, the science of mercury and the
    science of climate change, are both important and timely. I
    commend you for holding this hearing.
        I think I do not have to remind you that we have had
    hearings on climate change now during the last 4 or 5 years. I
    think I had a couple when I was chairman of even the
    Transportation Infrastructure Committee. Senator Lieberman had
    hearings over in Governmental Affairs when he was chairman of
    the committee a year or so ago. So it is not a subject that is
    brand new to this committee.
        I have stated time and time again here in the committee and
    on the floor that we must recognize that energy policy and
    environmental policy are two sides of the same coin, and the
    Senate has responsibility to harmonize these policies. We have
    an obligation here in the committee to ensure that legislation
    that we consider will protect our environment. We also have an
    obligation to ensure that any legislation we consider takes
    into account its potential impact on our economy and we have a
    moral obligation to ensure that we consider a bill's particular
    impact on the poor and the elderly who must survive on fixed
    incomes.
        When the Senate takes up consideration of climate change
    and multi-pollutant legislation, we must keep that moral
    obligation in mind. We must ensure that we do not pass
    legislation that will significantly drive up the cost of
    electricity and home heating for those who can least afford
    them.
        Several members of this committee have introduced pieces of
    legislation this year to reduce power plant emissions,
    including mercury, and address the issue of carbon emissions
    and climate change by capping carbon. Examples include
    Jeffords-Lieberman four-P bill, the Carper four-P bill, and the
    McCain-Lieberman climate change bill, which I understand will
    likely be offered as an amendment to the energy bill, just this
    week we are going to be considering it.
        These bills will establish a nationwide cap on carbon
    emissions and their passage would force the utility sector,
    that is now using coal to generate over half of our Nation's
    electricity. To rely solely on natural gas for generation, we
    will have fuel switching--capping carbon equals fuel switching
    equals no-coal--to rely on natural gas regeneration despite the
    fact we have over a 250-year supply of domestic coal and are
    currently in the grips of a natural gas crisis in this country.
        This crisis is a result of environmental policies that have
    driven up the use of natural gas in electricity generation
    significantly, while domestic supplies of natural gas have
    fallen, partly because we cannot do the exploration that we
    need to do for natural gas.
        The result is predictable: tightening supplies of natural
    gas, higher natural gas prices, and higher electricity prices.
    Home heating prices are up dramatically, forcing folks on low
    and fixed incomes to choose between heating their homes and
    paying for other necessities such as food or medicine. The
    language that has been offered by Senators Jeffords, McCain,
    Lieberman and Carper if enacted will force our utilities to
    fuel switch to natural gas; will significantly raise energy
    prices; and will cause thousands of jobs to be lost,
    particularly in manufacturing States like my State of Ohio,
    which is already under duress in terms of manufacturing.
        During the debate last year on the Jeffords-Lieberman four-
    P bill, I put together a white paper that discussed the impact
    that the bill would have if it were enacted. The numbers are
    staggering: an overall reduction in GDP of $150 billion by
    2020, the loss of over 900,000 jobs by 2020, and a decline in
    national household earnings of $550 annually.
        The cost of climate-change language such as the McCain-
    Lieberman bill could come without any benefits to our air
    quality or public health. Not even the most ardent supporter,
    and I hope this comes up, of carbon regulation will claim that
    there are demonstrable health benefits from carbon regulation.
    Yet the Energy Information Administration estimates that the
    passage of the McCain-Lieberman bill, if enacted, will raise
    petroleum product prices by 31 percent, raise natural gas
    prices by 79 percent, raise electricity prices by 46 percent,
    and reduce GDP by up to $93 billion by 2025.
        Carbon caps and unrealistic mercury caps means fuel
    switching, again. The fuel switching means the end of
    manufacturing in my State, enormous burdens on the least of our
    brethren. It means moving jobs and production overseas, where
    there are less stringent environmental programs. And will
    actually, if you really think about it, increase global levels
    of pollution.
        The question we face in this committee is whether we should
    do something reasonable to improve our understanding of the
    issues surrounding carbon emissions and climate change, and
    attempt to reduce atmospheric concentration of carbon and
    mercury emissions without harming our economy, or rush into
    short-sighted policy that will cap carbon and mercury at
    unreasonable levels, shut down our economy, cut thousands of
    jobs, and move manufacturing overseas.
        In a recent column, former Secretary of Energy James
    Schlesinger commented that:

              ``In climate change, we have only a limited grasp of the
            overall forces at work. Uncertainties have continued to abound
            and must be reduced. In any approach to policy formation, this
            is very important, under conditions of such uncertainty should
            be taken only on an exploratory or a sequential basis. A
            premature commitment to a fixed policy could only proceed with
            fear and trembling.''

        I would like to have that column inserted in the record,
    Mr. Chairman.
        Senator Inhofe. Without objection, so ordered.
        Senator Voinovich. As I mentioned previously once or twice,
    I am working with Chairman Inhofe and the Administration on
    moving Clear Skies forward, which I intend to mark up in my
    subcommittee this fall. I am currently working with business
    and environmental groups to find a bipartisan compromise on
    dealing with carbon and global warming, with an emphasis on
    sound science, carbon sequestration, development of clean coal
    technologies, and a responsible approach that focuses more on
    consensus rather than politics.
        We need more Senators to focus on moving forward in a
    responsible way and move away from harshly ideological
    positions that advance nothing other than the agenda of some
    environmental groups that have made carbon cap a political
    litmus test.
        I thank the chairman for holding this important hearing and
    I look forward to hearing the testimony from our witnesses.
        Senator Inhofe. That is an excellent opening statement,
    Senator Voinovich. I go back to one of your first sentences
    when you talked about the number of hearings we have had. We
    have to keep in mind that each new hearing has new data. For
    example, the 1,000-year Harvard-Smithsonian was not even out
    until March of this year. So there are new things that are
    coming along and I see a new trend-line which I discussed on
    the House of the Senate yesterday. So this will be a very
    valuable hearing.
        Senator Cornyn, would you have any opening statement to
    make?
        Senator Cornyn. I would like to reserve any statement until
    later, Mr. Chairman.
        Senator Inhofe. Yes, that is fine. First, I would like to
    ask the first panel to come up. Dr. Legates, Dr. Willie Soon
    and Dr. Mann, would you three come up? First of all, we are
    honored to have who I consider three very excellent and
    professional scientific witnesses here today. Normally, we
    restrict the opening statements to 5 minutes, but it would be
    fine if you want to go about 7 minutes because I know you have
    come a long way and what we are dealing with here is probably
    one of the most significant things facing America, facing our
    economy, facing our environment today.
        So I would introduce all three. Dr. David Legates is the
    director of the Center for Climatic Research at the University
    of Delaware. Dr. Willie Soon is the astrophysicist at Harvard-
    Smithsonian Center for Astrophysics, and Dr. Michael Mann is
    assistant professor at the University of Virginia Department of
    Environmental Sciences. I will first ask Dr. Willie Soon to
    give his opening statement.

     STATEMENT OF WILLIE SOON, ASTROPHYSICIST, HARVARD-SMITHSONIAN
                        CENTER FOR ASTROPHYSICS

        Dr. Soon. Mr. Chairman, distinguished Senators, my fellow
    panelists, Dr. Mann and Dr. Legates, and members of the
    audience, my name is Willie Soon. About a month or two ago, I
    became a very proud and grateful U.S. citizen. I just cannot
    believe where I am sitting today.
        I am an astrophysicist with the Harvard-Smithsonian Center
    for Astrophysics in Cambridge, Massachusetts. My training is in
    atmospherics and space physics. My research interests for the
    past 10 years include changes in the sun and their possible
    impact on climate.
        I am here today to testify that the climate of the 20th
    century is neither unusual nor the most extreme. Around 1,000
    years ago, the temperature over many parts of the world was
    warm. A widespread cooling then set in for several centuries,
    followed by a recovery to 20th century warming.
        My colleague and I collected the information on climate by
    proxy. We studied environmental indicators of local climate
    change going back some 1,000 years from many locations around
    the world. Based on work of approximately 1,000 researchers and
    hundreds of peer-reviewed papers, we conclude the following
    three points about climate history of the last 1,000 years.
        On a location-by-location basis, point No. 1, there was
    warming from 800 to 1300 A.D., all about 1,000 years ago, over
    many parts of the world. This period is called the Medieval
    Warm Period. Following the warming of 1,000 years ago was a
    general cooling from about 1300 to 1900 A.D. This period is
    called the Little Ice Age.
        Point No. 2, there is no convincing evidence from local
    proxy to suggest that the 20th century had higher temperatures
    or more extreme climate than the warm period 1,000 years ago.
        Point No. 3, local and regional, rather than global average
    changes are the most relevant and practical measure of climate
    changes and its impact. Much of the climate proxy results using
    our work are new. Most papers were published in the scientific
    literature in the recent 5 to 10 years. There are two points to
    note about our methods. First, we keep the local or regional
    information contained in each climate proxy. This is important
    for studying geographical patterns of climate, which does not
    change everywhere at the same time.
        Second, climate is more than just temperature, so we keep
    the climate information like rainfall, expansion or contraction
    of forests, all advances or retreats of glaciers, et cetera.
    Our approach makes use of the richness of information in
    climate proxies, which map out local environmental and climate
    properties, rather than just temperature alone.
        The entirety of climate proxies over the last 1,000 years
    shows that over many areas of the world, there has been and
    continues to be large local climatic changes. Those changes
    provide important changes for the computer simulations of
    climate. The full models which explore the Earth region by
    region can be tested against the natural patterns of change
    over the last 1,000 years that are detailed by the climate
    proxies.
        Having computer simulation, we produced past patterns of
    climate which has been influenced predominantly by natural
    factors and is key to making an accurate forecast that includes
    all potential human-made warming and cooling effects.
        In summary, based on expert conclusions from climate
    proxies in several hundred peer-reviewed papers by over 1,000
    researchers from around the world, we find the following. No.
    1, from one location to another, large natural swings in
    climate have occurred over the last 1,000 years. Those patterns
    have not always been synchronous.
        No. 2, there was widespread warmth about 1,000 years ago,
    followed by widespread cooling ending by the beginning of the
    20th century.
        No. 3, the local and regional climate proxies cannot
    confirm that the 20th century is the warmest or most extreme
    over much of the world, compared especially to the Medieval
    Warm Period approximately 1,000 years ago.
        This is all for my oral remarks and I thank you for the
    opportunity to be here.
        Senator Inhofe. Dr. Soon, we appreciate that excellent
    opening statement. You did not even take all of your time. That
    is very unusual.
        At this time, Dr. Mann if you don't mind, I would like to
    interrupt your testimony. We have been joined by the Ranking
    Minority Member, Senator Jeffords. Senator Jeffords, do you
    have an opening statement you would like to make at this time?
        Senator Jeffords. I would ask unanimous consent that it be
    made as part of the record and would prefer listening to the
    witnesses.
        [The prepared statement of Senator Jeffords follows:]

       Statement of Hon. James Jeffords, U.S. Senator from the State of
                                    Vermont

        We're here today to discuss two very important topics--climate
    change and mercury pollution. As most of you know, I am the author of
    ambitious legislation--the Clean Power Act of 2003--which addresses
    these environmental problems, as well as ozone, acid rain, and human
    health damage from fine particulate matter.
        Unfortunately, we aren't here today to talk about moving forward to
    find innovative solutions to these real world problems. Instead,
    today's hearing will largely be a mirror or the reverse of the robust
    and growing consensus in the mainstream scientific community on climate
    and mercury pollution.
        The disappointing result will be more delay. Delay on the part of
    Congress, and even worse, the ongoing backsliding on the part of the
    Administration, means that we fail to act responsibly as a society to
    protect future generations. That means increasingly greater risks of
    global warming and mercury poisoning.
        There is no doubt that the scientific process must inform
    policymakers as new information comes in. Unfortunately, there is no
    new information to be found here today that would dissuade us from
    acting quickly and responsibly to reduce greenhouse gas and mercury
    emissions. In today's discussion of a literature survey of climate
    research, the skeptics are trotting out an argument that is several
    years old and already discarded by their peers.
        It is abundantly clear that now is the time to act.
         The National Academy of Sciences has said, ``Despite the
    uncertainties, there is general agreement that the observed warming is
    real and particularly strong within the past 20 years.''

         NOAA currently says that,

              ``The climatic record over the last thousand years clearly
            shows that global temperatures increased significantly in the
            20th Century, and that this warming was likely to have been
            unprecedented in the last 1200 years.''

         EPA's website says that, ``There is new and stronger
    evidence that most of the warming over the last 50 years is
    attributable to human activities.''
        One would have to be madder than a March hare to fail to see the
    need to act. Yet, the Administration's new research plan falls squarely
    into hare territory--denying the reality staring them in the face.
        I want to show you the latest odds on warming. MIT says that there
    is a one in five chance that the temperature of the earth will warm by
    approximately 4 or 5 degrees over the course of this century, assuming
    there is no action to reduce emissions.
        As my dear departed friend, Senator John Chafee, said in 1989:

              ``It is clear that we are facing a serious threat. The
            scientists are telling us that if we continue to stroll along
            as if everything is fine, we will transform Earth into a planet
            that will not be able to support life as we now know it.''

        While mercury contamination does not have the same dramatic effect
    on earth's systems, it is still a dangerous global and local pollutant
    because it is bio-accumulative and toxic to human health.
        Long ago, Congress decided that toxic air emissions should be
    reduced and took very aggressive steps in 1990 to make that happen,
    especially if they fall into the Great Lakes and other great waters
    like Lake Champlain. Unfortunately, the Agency has fallen significantly
    behind in complying with the Clean Air Act's schedule. A settlement
    agreement mandates controlling toxic air pollutants from utilities by
    2008.
        In 1998, related to the controversy around EPA's late reports to
    Congress on utility air toxics, Congress directed the National Academy
    of Sciences (NAS) to recommend an appropriate reference dose for
    mercury exposure. In 2000, the NAS reported that EPA's reference dose
    was scientifically sound and adequate to protect most Americans. That
    NAS review considered all health effects studies, including the
    Seychelles study that we'll discuss today.
        We know that mercury is a potent toxic. It affects the human brain,
    spinal cord, kidneys, liver and the heart. It affects the ability to
    feel, see, taste and move. We know that mercury can affect fetal
    development, preventing the brain and nervous system from developing
    normally. Long term exposure to mercury can result in stupor, coma and
    personality changes.
        ``Mad as a Hatter'' is the phrase that was used in the 1800's to
    describe the employees of the felt hat industry whose constant exposure
    to mercury changed their behavior. Fortunately, Americans exposure from
    commercial and recreational fish consumption is substantially less than
    that, though dozens of health warnings are posted nationwide.
        But, it's crazy for anyone to suggest that we should not reduce
    mercury emissions significantly, since we know its health effects and
    we have the technologies to control it.
        We should have a hearing on how to export those control
    technologies and Congress should urge the Administration to negotiate
    binding global reductions in mercury, as the Senate did last year in
    the Energy bill for greenhouse gas emissions.
        At a minimum, we should pass four-pollutant legislation now that
    gets reductions faster and deeper than required by the current Clean
    Air Act. I'm sad to say that there have been no negotiations on that
    front since I initiated some in early 2002. And the Administration has
    done nothing to reduce these emissions with its abundant authority in
    the Act.
        We can't afford to leave these problems to future generations to
    solve. We can't let our children and grandchildren wake up to find that
    our delays have cost them dearly in terms of health and the global and
    local environment. It's time to act responsibly.
        Finally, I ask that material from the journal EOS, the NOAA
    website, the Atlanta Journal Constitution, the National Center for
    Atmospheric Research, and the American Geophysical Union be included in
    the hearing record.

        Senator Jeffords. I might point out, we have got to do
    something about this traffic out there.
        [Laughter.]
        Senator Inhofe. Well, the name of our subcommittee is
    Transportation and Infrastructure, so maybe we can do something
    about the traffic out there.
        Senator Jeffords. I hope so.
        Senator Inhofe. Dr. Mann, you are recognized.

     STATEMENT OF MICHAEL E. MANN, ASSISTANT PROFESSOR, UNIVERSITY
           OF VIRGINIA, DEPARTMENT OF ENVIRONMENTAL SCIENCES

        Dr. Mann. Senators, my name is Michael Mann. I am a
    professor in the Department of Environmental Sciences at the
    University of Virginia. My research involves the study of
    climate variability and its causes. I was a lead author of the
    IPCC Third Scientific Assessment report. I am current
    organizing committee chair for the National Academy of
    Sciences' Frontiers of Science, and have served as a committee
    member or adviser for other National Academy of Sciences'
    panels.
        I have served as editor for the Journal of Climate of the
    American Meteorological Society for 3 years and I am a member
    of the advisory panel for the NOAA Climate Change Data and
    Detection Program. I am a member of numerous other
    international and U.S. scientific working groups, panels and
    steering committees. I have coauthored more than 60 peer-
    reviewed publications on diverse topics within the fields of
    climatology and paleoclimatology.
        Honors I have received include selection in 2002 as one of
    the 50 leading visionaries in science and technology by
    Scientific American magazine, and the outstanding scientific
    publication award of NOAA for 2000.
        In my testimony here today, I will explain, No. 1, how
    mainstream climate researchers have come to the conclusion that
    late 20th century warmth is unprecedented in a very long-term
    context and that this warmth is likely related to the activity
    of human beings; and No. 2, why a pair of recent articles
    challenging these conclusions by astronomer Willie Soon and his
    coauthors are fundamentally unsound.
        It is the consensus of the climate research community that
    the anomalous warmth of the late 20th century cannot be
    explained by natural factors, but instead indicates significant
    anthropogenic, that is human influences. This conclusion is
    embraced by the position statement on climate change and
    greenhouse gases of the American Geophysical Union, by the 2001
    report of the IPCC, the Intergovernmental Panel on Climate
    Change, and by a National Academy of Sciences' report that was
    solicited by the Bush Administration in 2001.
        More than a dozen independent research groups have now
    reconstructed the average temperature of the northern
    hemisphere in past centuries, both by employing natural
    archives of past climate information or proxy indicators such
    as tree rings, corals, ice cores, lake sediments and historical
    documents, and through the use of climate model simulations. If
    I can have the first exhibit here, as shown in this exhibit,
    the various proxy reconstructions agree with each other, as
    well as with the model simulations, all of which are shown,
    within the estimated uncertainties. That is the gray-shaded
    region.
        The proxy reconstructions, taking into account these
    uncertainties, indicate that the warming of the northern
    hemisphere during the late 20th century, that is the northern
    hemisphere, not the globe, as I have sometimes heard my study
    incorrectly referred to, the northern hemisphere during the
    late 20th century, that is the end of the red curve, is
    unprecedented over at least the past millennium and it now
    appears based on peer-reviewed research, probably the past two
    millennia.
        The model simulations demonstrate that it is not possible
    to explain the anomalous late-20th century warmth without the
    contribution from anthropogenic influences. These are the
    consensus conclusions of the legitimate community of climate
    and paleoclimate researchers investigating such issues.
        Astronomers Soon and Baliunas have attempted to challenge
    the scientific consensus based on two recent papers, henceforth
    collectively referred to as SB, that completely misrepresent
    the past work of other legitimate climate researchers and are
    deeply flawed for the following reasons. No. 1, SB make the
    fundamental error of citing evidence of either wet or dry
    conditions as being in support of an exceptional Medieval Warm
    Period. Such an ill-defined criterion could be used to define
    any period of climate as either warm or cold. It is pure
    nonsense.
        Experienced paleoclimate researchers know that they must
    first establish the existence of a temperature signal in a
    proxy record before using it to try to reconstruct past
    temperature patterns. If I can have exhibit two, this exhibit
    shows a map of the locations of a set of records over the globe
    that have been rigorously analyzed by my colleagues and I for
    their reliability as long-term temperature indicators. I will
    refer back to that graphic shortly.
         No. 2, it is essential to distinguish between regional
    temperature changes and truly hemispheric or global changes.
    Average global or hemispheric temperature variations tend to be
    far smaller in their magnitude than those for particular
    regions. This is due to a tendency for the cancellation of
    simultaneous warm and cold conditions in different regions,
    something that anybody who follows the weather is familiar
    with, in fact.
        As shown by exhibit three, if I can have that up here as
    well now, thank you, this exhibit plots the estimated
    temperature for various locations shown in the previously
    displayed map. As you can see, the specific periods of relative
    cold and warm, blue and red, differ greatly from region to
    region. Climatologists, of course, know this. What makes the
    late 20th century unique is the simultaneous warmth indicated
    by nearly all the long-term records. It is this simultaneous
    warmth that leads to the anomalous late-20th century warmth
    evident for northern hemisphere average temperatures.
        The approach taken by SB does not take into account whether
    warming or cooling in different regions is actually coincident,
    despite what they might try to tell you here today.
         No. 3, as it is only the past few decades during which
    northern hemisphere temperatures have exceeded the bounds of
    natural variability, any analysis such as SB that compares past
    temperatures only to early or mid-20th century conditions; you
    repeatedly hear Dr. Soon refer to the 20th century;
    climatologists do not consider that a meaningful baseline
    because there has been a dramatic warming during the 20th
    century and the early 20th century and the late 20th century
    are almost as different as the late 20th century and any other
    period during the past 1,000 years at least. So a study that
    refers only to early or mid-20th century conditions or generic
    20th century conditions and does not specifically address the
    late 20th century, cannot address the issue of whether or not
    late-20th century warmth is anomalous in a long-term context.
        To summarize, late-20th century warming is unprecedented in
    modern climate history at hemispheric scales. A flawed recent
    claim to the contrary by scientists lacking expertise in
    paleoclim-
    atology is not taken seriously by the scientific community.
        The anomalous recent warmth is almost certainly associated
    with human activity and this is the robust consensus view of
    the legitimate climate research community.
        Thank you.
        Senator Inhofe. Thank you, Dr. Mann.
        Dr. Legates.
        First, I would ask Senator Allard, did you want to make an
    opening statement?
        Senator Allard. Mr. Chairman, I do have an opening
    statement and in deference to the panel and you I would just
    like to have it put in the record. If you would do that, then I
    would be happy.
        Senator Inhofe. Without objection.
        [The prepared statement of Senator Allard follows:]

    Statement of Hon. Wayne Allard, U.S. Senator from the State of Colorado

        Mr. Chairman, I want to thank you for holding this important
    hearing today.
        As a veterinarian, I have some scientific training in my
    background. I strongly believe that we should use scientific principals
    as a guidepost when formulating any regulation. This scientific
    guidepost approach is particularly important when looking at
    regulations with the implications and magnitude of regulations on
    climate change and mercury control.
        Climate change has been an ongoing discussion for many years.
    However, during the 1970's the concerns were exactly opposite of what
    they are now. Then we were told that there was a threat of massive
    global cooling. Headlines screamed that we were in danger of entering
    another ice age. Now we are told that massive warming trends are going
    to cause overheating across the globe. We need answers, not rhetoric.
        All of the witnesses here today have a great deal of experience.
    All of the witnesses here have spent many years analyzing data related
    to the areas of their expertise. But, I am concerned that, at times,
    data may be reviewed selectively and in isolation. I am also concerned
    that emphasis may fall on a limited number of studies. In science we
    have all learned that the only way to solidly prove a theory is by
    conducting tests, studies or experiments that repeatedly arrive at the
    same result. We cannot simply ignore the studies that do not have the
    outcome we are looking for. This applies whether we are looking at
    climate change, mercury or any other issue.
        I want to spend most of my time and attention today on potential
    mercury regulations. While today's hearing is intended to focus on
    science, I would also like to touch on the impact that potential
    regulations will have on the economy of my state and the west. As many
    of you know, western coal differs from other types of coal in several
    ways. The higher chlorine content in western coal makes it more
    difficult to remove mercury when burning it. And, while western coal
    does contain mercury, when it is burned it gives off mercury in the
    elemental form. It is my understanding that this is not the type of
    mercury that deposits in the ecosystem to potentially be absorbed by
    the environment.
        The economies of Colorado, and the entire west, will be impacted by
    harsh regulations placed on their coal. Economies undoubtedly will be
    damaged by the decrease in use of coal mined in the West. In addition,
    while jobs are being lost due to the subsequent inability to fully
    utilize western coal supplies, if power can no longer be generated by
    using coal mined in the west, other less efficient coal types will have
    to be transported across long distances. This additional expenditure
    will add to the price of electricity generation, driving up electricity
    costs and further damaging an economy that will already be struggling.
        This is why it is so important to me that we be cautious when
    dealing with situations such as these and why we should place strong
    emphasis on the use of sound science. Our regulations must be
    thoughtful reflections of what we know--they should not be reflexive or
    reactive attempts to legislate a cure before we know what the disease
    is.
        Again, Mr. Chairman, thank you for holding this hearing. I look
    forward to hearing the witness testimony and discussions to come.

        Senator Inhofe. That being the case, let's dispense with
    any further opening statements.
        Dr. Legates, thank you very much for being here. You are
    recognized.

     STATEMENT OF DAVID R. LEGATES, DIRECTOR, CENTER FOR CLIMATIC
                    RESEARCH, UNIVERSITY OF DELAWARE

        Dr. Legates. Thank you. Mr. Chairman, Distinguished
    Senators, Doctors Mann and Soon, and members of the audience, I
    would like to thank the committee for inviting my commentary on
    this important topic of climate history and its implications.
    My research interests have focused on hydroclimatology. That is
    the study of water in the atmosphere and on the land, and as
    well as on the application of statistical methodology in
    climatological research.
        I am familiar with the testimony presented here by Dr.
    Soon. My contributions to Dr. Soon's research stem from my
    grappling with the striking disagreement between the
    longstanding historical record and the time series recently
    presented by Dr. Mann and his colleagues. It also stems from my
    own experiences in compiling and merging global estimates of
    air temperature and precipitation from a variety of disparate
    sources.
        My Ph.D. dissertation resulted in the compilation of high-
    resolution climatologies of global air temperature and
    precipitation. From that experience, I have become acutely
    aware of the issues associated with merging data from a variety
    of sources and containing various biases and uncertainties. By
    its very nature, climatological data exhibit a number of
    spatial and temporal biases that must be taken into account.
    Instrumental records exist only for the last century or so, and
    thus proxy records can only be used to glean information about
    the climate for earlier time periods. But it must be noted that
    proxy records are not observations and strong caveats must be
    considered when they are used. It, too, must be noted that
    observational data are not without bias either.
        Much research has described both the written and oral
    histories of the climate, as well as the proxy climate records.
    It is recognized that such records are not without their
    biases. For example, trees respond not to just air temperature
    fluctuations, but to the entire hydrologic cycle, including
    water supply, precipitation, and demand, which is only in part
    driven by air temperature.
        Nevertheless, such accounts indicate that the climate of
    the last millennium has been characterized by considerable
    variability and that extended periods of cold and warmth
    existed. It has been generally agreed that during the early
    periods of the last millennium, air temperatures were warmer
    and that temperatures became cooler toward the middle of the
    millennium. This gave rise to the terms the Medieval Warm
    Period and the Little Ice Age, respectively. However, as these
    periods were not always consistently warm or cold, nor were the
    extremes geographically commensurate in time, such terms must
    be used with care.
        In a change from its earlier reports, however, the Third
    Assessment Report of the Intergovernmental Panel on Climate
    Change, and now the U.S. National Assessment of Climate Change,
    both indicate that hemispheric and global air temperatures
    followed a curve developed by Dr. Mann and his colleagues in
    1999. This curve exhibits two notable features, and I will
    point back to Dr. Mann's exhibit one that he showed a moment
    ago. First is a relatively flat and somewhat decreasing trend
    in air temperature that extends from 1000 A.D. to about 1900
    A.D. This feature is an outlier that is in contravention to
    thousands of authors in the peer-reviewed literature.
        This is followed by an abrupt rise in the air temperature
    during the 1900's that culminates in 1998 with the highest
    temperature on the graph. Virtually no uncertainty is assigned
    to the instrumental record of the last century. This conclusion
    reached by the IPCC and the National Assessment is that the
    1990's was the warmest decade, with 1998 being the warmest year
    of the last millennium.
        Despite the large uncertainty, the surprising lack of
    significant temperature variations in the record gives the
    impression that climate remained relatively unchanged
    throughout most of the last millennium, at least until human
    influences began to cause an abrupt increase in temperatures
    during the last century. Such characterization is a scientific
    outlier. Interestingly, Mann et al replace the proxy data for
    the 1900's by the instrumental record and present it with no
    uncertainty characterization. This, too, yields the false
    impression that the instrumental record is consistent with the
    proxy data and that it is error-free. It is neither.
        The instrumental record contains numerous uncertainties,
    resulting from measurement errors, a lack of coverage over the
    world's oceans, and underrepresentation of mountainous and
    polar regions, as well as undeveloped nations and the presence
    of urbanization effects resulting from the growth of cities. As
    I stated before, the proxy records only in part reflect
    temperature. Therefore, a simultaneous presentation of the
    proxy and instrumental record is the scientific equivalent to
    calling apples and oranges the same fruit.
        Even if a modest uncertainty of plus or minus one-tenth of
    a degree Celsius were imposed on the instrumental record, the
    claim of the 1990's being the warmest decade would immediately
    become questionable, as the uncertainty window would overlap
    with the uncertainty associated with earlier time periods.
    Note, too, that if the satellite temperature record, where
    little warming has been observed over the last 20 years, had
    been inserted instead of the instrumental record, it would be
    impossible to argue that the 1990's was the warmest decade.
    Such a cavalier treatment of scientific data can create
    scientific outliers, such as the Mann et al curve.
        So we are left to question why the Mann et all curve seems
    to be at variance with the previous historical characterization
    of climatic variability. Investigating more than several
    hundred studies that have developed proxy records, we came to
    the conclusion that nearly all of these records show
    considerable fluctuations in air temperature over the last
    millennium. Please note that we did not reanalyze the proxy
    data. The original analysis from the various experts was left
    intact, as it formed a voluminous refereed scientific
    literature. Most records show the coldest period is
    commensurate with at least a portion of what is termed the
    Little Ice Age, and the warmest conditions at concomitant with
    at least a portion of what is termed the Medieval Warm Period.
        Our conclusion is entirely consistent with conclusions
    reached by Drs. Bradley and Jones and not all locations on the
    globe experience cold or warm conditions. Moreover, we chose
    not to append the instrumental record, but to compare apples
    with apples and determine if the proxy records themselves
    indeed confirm the claim of the 1990's being the warmest decade
    of the last millennium. That claim is not borne out by the
    individual proxy records.
        However, the IPCC report in the chapter with Dr. Mann as
    the lead author and his colleagues as contributing authors,
    also concludes that the research ``support the idea that the
    15th to 19th centuries were the coldest of the millennium over
    the northern hemisphere overall.'' Moreover, the IPCC report
    also concludes that the Mann and Jones research shows
    temperatures from the 11th to 14th centuries to be ``warmer
    than those from the 15th to 19th centuries.'' This again is
    entirely consistent with our findings and in contravention of
    their own error assessment.
        Where we differ with Dr. Mann and his colleagues is in the
    construction of the hemisphere average time series and their
    assertion that the 1990's was the warmest decade of the last
    millennium. Reasons why the Mann et al curve fails to retain
    the fidelity of the individual proxy records are detailed
    statistical issues into which I will not delve. But a real
    difference of opinion focuses solely on the Mann et al curve,
    and how it is an outlier compared to the balance of evidence on
    millennial climate change. In a very real sense, this is a
    fundamental issue that scientists must address before the Mann
    et al curve can be taken as fact.
        In closing, let me state that climate is simply more than
    annually averaged global air temperature. Too much focus, I
    believe, has been placed on defining air temperature time
    series and such emphasis obscures the true issue in
    understanding climate change and variability. If we are truly
    to understand climate and its impacts and driving forces, we
    must push beyond the tendency to distill climate to a single
    annual number. Proxy records which provide our only possible
    link to the past are incomplete at best. But when these
    voluminous records are carefully and individually examined, one
    reaches the inescapable conclusion that climate variability has
    been a natural occurrence and especially so over the last
    millennium.
        Given the uncertainties and biases associated with the
    proxy and instrumental records----
        Senator Inhofe. Dr. Legates, we are going to have to cut it
    off. You have exceeded your time and I am sure you will have an
    opportunity to finish your thoughts during the question and
    answer period.
        Dr. Legates. Thank you for the privilege.
        Senator Inhofe. We are going to, if it is all right, use 5
    minutes and maybe try to get a few rounds here. Is that
    acceptable? These will be 5 minute rounds for questioning. I
    will start.
        First of all, Senator Thomas joined us. Thank you for
    coming, Senator Thomas.
        I will address my first question to Dr. Legates. In my
    speech on the Senate floor yesterday, I noted your comments
    regarding--can you find that chart of those comments?--the
    comments regarding Dr. Mann's work as shown on the chart. I
    have a small copy of this. No, that is not it. It is this chart
    right here. OK.
        First of all, this is a comparison. As I mentioned in my
    opening statement, we sit up here as non-scientists so we try
    to look at these things and see what is logical, how we should
    weigh and compare diverse opinions. Now, the first thing I
    noticed was that Dr. Mann, yours I believe was in the area of
    the timeframe of 1999----
        Dr. Mann. Excuse me. That is incorrect.
        Senator Inhofe [continuing]. And Dr. Soon, you are 2003. So
    I think that the timing would mean something because I know
    that this is not a static target. This is a moving target.
        May I first ask Dr. Legates, do you stand by the statements
    that are made on this chart up here, on the contrasting methods
    that were used?
        Dr. Legates. I have not had a chance to actually look at
    the chart before now.
        Senator Inhofe. Is this the one that he had here? OK, let's
    put that up. All right, then, this statement here,

              ``Although Mann's work is now widely used as proof of
            anthropogenic global warming. We have become concerned that
            such analysis is in direct contradiction to most of the
            research and written histories available. My paper shows this
            contradiction and argues that the results of Mann are out of
            step with the preponderance of the evidence.''

        I am not Tim Russert, but do you stand by these statements?
        Dr. Legates. I do stand by them, sir.
        Senator Inhofe. All right. I note that you are an expert in
    statistical techniques. In my speech on the Senate floor
    yesterday, I noted that even assuming all of the science used
    by the political left, come the end of 50 years hence, the
    Kyoto Protocol would have no measurable affect on temperature.
    Do you agree with that?
        Dr. Legates. Yes, generally.
        Senator Inhofe. And if the Kyoto Protocol forces harsher
    mandates, does it follow that the weaker legislative proposals
    that are out there right now before us in the Senate would have
    likewise no measurable effect?
        Dr. Legates. That is likely true.
        Senator Inhofe. All right. Let's see. Dr. Mann, since you
    have characterized your colleagues there in several different
    ways as nonsense, illegitimate, and inexperienced, let me ask
    you if you would use the same characterization of another
    person that I quoted on the floor yesterday. I would like to
    call your attention to the recent op/ed in the Washington Post
    by Dr. James Schlesinger, who was Energy Secretary under
    President Carter. In it, he wrote, ``There is an idea among the
    public that the science is settled. That remains far from the
    truth.'' He has also acknowledged the Medieval Warming Period
    and the Little Ice Age. Do you question the scientific
    integrity of Dr. Schlesinger?
        Dr. Mann. I do not think I have questioned scientific
    integrity. I have questioned scientific expertise in the case
    of Drs. Willie Soon and David Legates with regard to issues of
    paleoclimate. As far as Schlesinger is concerned, I am not
    familiar with any peer-reviewed work that he has submitted to
    the scientific literature, so I would not be able to evaluate
    his comments in a similar way. If I could clarify one----
        Senator Inhofe. OK. Well, you can't because there isn't
    time. I am going to stay within my timeframe and I want to get
    to questions so others will have plenty of opportunity to
    respond to questions I am sure.
        Dr. Soon, how many studies did you examine in total and how
    many were appropriate for the criteria you established?
        Dr. Soon. Senator, the number is roughly in the order of,
    if you speak in terms of the peer-reviewed literature, I would
    say several hundred. And the number of people involved in these
    paleoclimatic research would be at least 1,000. Of course, I
    have to emphasize I am not a paleoclimate scientist, but all of
    us are ruled by one simple goal, to understand the nature of
    how climate works. The basis to get to the goal is to figure
    out the exact expressions of the physical laws.
        The short answer is there is a huge number of literature
    that we consulted that feed the criteria. This is why we wrote
    it as a scientific paper.
        Senator Inhofe. I was trying to get to the 240 proxies that
    were used and the number used.
        Dr. Soon. Yes, we listed about 240 proxy studies in our
    papers.
        Senator Inhofe. Last, I would say, do you have more data in
    your study than Dr. Mann did in his 1999 work? And is your data
    newer?
        Dr. Soon. Yes. I would emphasize that most of the proxy
    records come from the most recent 5 years.
        Senator Inhofe. Thank you, Dr. Soon.
        Senator Jeffords.
        Senator Jeffords. Dr. Mann, would you care to respond?
        Dr. Mann. Yes, first of all I wanted to clarify a
    misstatement earlier on the part of Senator Inhofe. The results
    that I showed in my first graphic which demonstrate that it is
    a clear consensus of the climate research community that a
    number of different estimates, not just ours, but at least 12
    different estimates of the history of the northern hemisphere
    average temperature for the past 1,000 years give essentially
    the same result, within the uncertainties. We published a paper
    just a month ago demonstrating that that is a robust result of
    a large number of mainstream researchers in the climate
    research community.
        Phil Jones and I also have a paper in press in the Journal
    of Geophysical Research letters, which demonstrates those
    results further. So in fact, the latest word and the word of
    the mainstream climate research community is the one that I
    have given you earlier.
        Now, as far as the issue of data, how much data was used,
    there are a number of misstatements that have been made about
    our study. One of them is with regard to how much data we used.
    We used literally hundreds of proxy records. We often
    represented those proxy records, as statistical climatologists
    often do, in what we call a state space. We represented them in
    terms of a smaller number of variables to capture the leading
    patterns of variability in the data. But we used hundreds of
    proxy indicators, more in fact than Dr. Soon referred to. In
    fact, we actually analyzed climate proxy records. Dr. Soon did
    not.
        Senator Jeffords. Dr. Soon, in a 2001 article in Capitalism
    magazine, you said that because of the pattern of frequent and
    rapid changes in climate throughout the holocene period, we
    should not view the warming of the last 100 years as a unique
    event or as an indication of manmade emissions' effect on the
    climate.
        But according to NOAA's Web site ``upon close examination
    of these warm periods,'' including all the ones that you cited
    in your past and most recent article,

              ``It became apparent that these periods are not similar to
            the 20th century warming for two specific reasons. One, the
            periods of hypothesized past warming do not appear to be global
            in extent or, two, the period of warmth can be explained by
            known natural climate forcing conditions that are uniquely
            different than those of the past 100 years.''

        Why didn't either of your articles make an impact on the
    state of the science or NOAA's position?
        Dr. Soon. Thank you for your question, Senator. As you may
    be aware, my paper just got published this year, January 2003
    and April 2003, so it is all fairly recent. I have just written
    up this paper very recently, so I do not know what impact it
    will have on any general community, but I do know all my works
    are done consulting works from all major paleoclimatologists in
    the field, including Dr. Mann and his esteemed colleagues.
        As to the comments about the Capitalism magazine, I am not
    aware of that particular magazine. I do not know whether I
    submitted anything to this journal or this magazine. I do stand
    by the statement that it is important to look at the local and
    regional change before one takes global averages because
    climate tends to vary in very large swings in different parts
    of the world. That really is the essence of climate change and
    one ought to be really looking very carefully at the local and
    regional change first, and also one should not look strictly at
    only the temperature parameter, as Dr. Mann has claimed to have
    done. That I think is very important to take into account.
        Senator Jeffords. Dr. Mann, could you comment?
        Dr. Mann. Yes. Both of those statements are completely
    incorrect. If Dr. Soon had actually read any of the papers that
    we have published over the past 5 years or so, he would be
    aware of the fact that we use statistical techniques to
    reconstruct global patterns of surface temperature. We average
    those spatial patterns to estimate a northern hemisphere mean
    temperature, just as scientists today seek to estimate the
    northern hemisphere average temperature from a global network
    of thermometer measurements. We use precisely the same approach
    based on proxy reconstructions of spatial patterns of surface
    temperature.
        So what Dr. Soon has said is completely inaccurate. The
    first line on that contrasting methods table up there is also
    completely inaccurate.
        In terms of variables other than temperature, my colleagues
    and I have published several papers reconstructing continental
    drought over North America and reconstructed sea-level pressure
    patterns. We have looked at just about every variable that
    climatologists are interested in from the point of view of
    paleoclimate indicators. I think Dr. Soon needs to review my
    work more carefully.
        Senator Inhofe. Thank you, Senator Jeffords.
        Senator Allard.
        Senator Allard. Thank you, Mr. Chairman.
        In my mind, I do not think there is any question that the
    climate has shown a period of warming here. The question that I
    bring up and where I see the debate is, what is causing it and
    whether it is the changes that are happening and whether they
    are significant or not.
        I also wonder what your thinking this world might look like
    1,000 years from now, looking at the data that we have now. I
    wondered if maybe each one of you would just give me a brief
    response as to what you think of what we are seeing today may
    look like projected out over 1,000 years from now. I will start
    with Dr. Soon.
        Dr. Soon. The factors causing climate change are extremely
    complicated. As I emphasized already, I am very much interested
    to learn how the climate changes on a local or regional scale
    first before I can speak in terms of global climate. After all,
    local and regional climate are indeed the most relevant
    climatic factors that human activities are being influenced by
    or the reverse way.
        As to the factors of climate change, I believe that it is
    extremely difficult yet still to confirm the facts of being,
    let's say, even the late 20th century has anything to do with
    CO2. We do know that the CO2 is rising,
    but at the same time we know that climate depends on many other
    factors. It could be doing it internally all by itself because
    of ocean current movements. It could be done, for example, by
    variability imposed externally from the sun, variable outputs.
    Our sun is a variable star. That is a very well known fact.
        These are the kinds of factors one has to look very
    comprehensively at. Additional important factors of human
    activity would include land use changes. Those are very well
    known factors that one has to keep a good record, or time
    history, to really understand what are the causes of the
    change.
        I don't think I should speculate anything about futures. It
    is always very dangerous to talk about the future of any
    climate.
        Senator Allard. Dr. Mann.
        Dr. Mann. Yes. Well, I certainly agree with your statement
    that one of the key issues is what we call the detection or the
    attribution of human influence on climate, not just how has
    climate changed over the past 100 years or past 1,000 years,
    but can we actually determine the causal agents of change.
        There has been a solid decade of research into precisely
    that question by, again, the mainstream climate research
    community in addressing the issue of the relative role of
    natural factors, as well as anthropogenic factors. That
    includes the role of the sun, the role of human land use
    changes, and the role of human greenhouse gas increases. The
    model estimates are typically consistent with what we have seen
    in the observations earlier.
        As far as the next 1,000 years, that is not a particular
    area of expertise of mine, but I am familiar with what the
    mainstream climate research community has to say about that.
    The latest model-based projections indicate a mean global
    temperature increase of anywhere between .6 and 2.2 degrees
    Centigrade. That is one degree to four degrees Fahrenheit
    relative to 1990 levels by the mid-21st century under most
    scenarios of future anthropogenic changes.
        While these estimates are uncertain, even the lower value
    would take us well beyond any previous levels of warmth seen
    over at least the past couple of millennia. The magnitude of
    warmth, but perhaps more importantly the unprecedented rate of
    warming, is cause for concern.
        Senator Allard. Dr. Legates.
        Dr. Legates. Yes. I agree, too, that attribution is one of
    our important concerns. As a climatologist, I am very much
    interested in trying to figure out what drives climate. We know
    that a variety of factors exist. These include solar forcing
    functions; these include carbon dioxide in the atmosphere;
    these include biases associated with observational methods;
    these also include such things as land use changes. For
    example, if we change the albedo or reflected amount solar
    radiation, that too will change the surface temperature.
        So it is really a difficult condition to try to balance all
    of these possible combinations and to try to take a very short
    instrumental record and discern to what extent that record is
    being driven by a variety of different combinations.
        My conclusion probably in this case to directly answer your
    question is that the temperature likely would rise slightly,
    again due to carbon dioxide, but it would be much more
    responsive to solar output. If the sun should quiet down, for
    example, I would expect we would go into a cooling period.
        Senator Allard. I guess the question that I would have,
    now, you know you have increased CO2. So how is the
    environment in the Earth going to respond to increased
    CO2? Have any of you talked to a botanist or
    anything to give you some idea of what happens when
    CO2 increases in the atmosphere? Plants utilize
    CO2, extract oxygen. We inhale oxygen and extract
    CO2. Will plants be more prosperous with more
    CO2? How does that impact the plant life? Can that
    then come back on the cycle and some century later mean more
    O2 and less CO2?
        So I am wondering if any of you have reviewed some of these
    cycles with botanists and see if they have any scientific data
    on how plants respond to CO2 when that is the sole
    factor. I am not sure I have ever seen a study. There is
    moisture and other things that affect plant growth, but just
    CO2 by itself. Have any of you seen any scientific
    studies in that regard?
        Dr. Soon. I have seen that. In fact, I have written a small
    paper that has a small section regarding that.
        Senator Allard. And what was their conclusion?
        Dr. Soon. The conclusion is that in general, of course,
    under enrichment of the CO2 in the free air, that
    yes, plant growth will be enhanced. For example, as indicated
    by your chart, the crop yield can increase by 30 percent or
    higher for a doubling of CO2, depending on the
    actual constraints in the field, like types of crops, how wet
    or how dry, etc. All of these examples are very well known and
    well verified in the field of botany.
        Senator Allard. My time has run out. Would the other two
    agree with what he said?
        Dr. Mann. Not quite.
        Senator Allard. What is your modification?
        Dr. Mann. In fact, a number of studies have been done, what
    are called ``FACE'' experiments. They are open canopy
    experiments in which CO2 is elevated in the forest
    and scientists examine the changes in the behavior of that
    forest. What scientists at Duke University are finding is that
    while there is a tendency for an uptake of CO2 by
    the plants in the near term, what happens is eventually those
    plants will die. They will rot. When that happens, this happens
    on generational time scales.
        Senator Allard. Just CO2 being the variable and
    not moisture and anything else?
        Dr. Mann. Just CO2. The CO2 will go
    back into the atmosphere because the plants that take it up----
        Senator Allard. Do they have an explanation of why the rot
    occurred?
        Dr. Mann. Well, just when things die, they will rot and
    they will give up their CO2 back to the atmosphere
    eventually.
        Senator Allard. Well, that really does not get to the point
    I was trying to make.
        Doctor.
        Dr. Legates. To follow on that, enhanced CO2 and
    dying plants would also provide the ability for more plants to
    therefore grow in its place. In particular, one of the people
    on our study, Dr. Sherwood Idso, has done a lot of this study
    with carbon dioxide and enhanced where you can control the
    amount of water and energy available to plants associated with
    lowered CO2 and higher CO2.
        Senator Allard. So your conclusion is that CO2
    increases plant growth?
        Dr. Legates. Yes.
        Senator Allard. OK.
        Thank you, Mr. Chairman.
        Senator Inhofe. Thank you, Senator Allard.
        Senator Carper, we were going to go by the early bird rule.
    Is it all right if Senator Thomas goes ahead of you here?
        Senator Carper. Sure.
        Senator Inhofe. Senator Thomas.
        Senator Thomas. Thank you. I am a little confused about
    where we even ask the questions. Obviously, there is a
    difference of view. We are expected to make some policy
    decisions based on what we ought to be doing with regard to
    these kinds of things, but yet there does not seem to be a
    basis for that kind of a decision. Where would you suggest we
    get the information that is the best information we could get
    to make policy decisions for the future? Would each of you like
    to comment shortly on that?
        Dr. Mann. Sure. I guess I would reiterate the comments that
    I made earlier, that in a National Academy of Sciences study
    that was commissioned by the Bush Administration in 2001, the
    National Academy of Sciences in essence stated their agreement
    with the major scientific findings of the Intergovernmental
    Panel on Climate Change, the IPCC, which is the United Nations
    panel of scientists, thousands of scientists from around the
    world who put together a report on the state of our knowledge
    about all of these things--climate change scenarios, our
    uncertainty about various attributes of the climate system. The
    conclusions that I stated earlier are the consensus conclusions
    of the IPCC.
        Senator Thomas. That is where you would go.
        Dr. Mann. That is where they have gone, yes.
        Dr. Legates. I would generally argue the IPCC is a bit of a
    political document to the extent to which it does present some
    biased science. There is a lot of good science in there, but a
    lot of the conclusions are sort of not borne out by the facts.
    Having been president of the Climate Specialty Group of the
    Association of American Geographers, which is probably the
    largest group of climatologists available, I know from talking
    to rank-and-file members that they generally--my impression is
    that most climatologists agree it takes a rather strong
    viewpoint.
        So I have real serious concerns that it really represents a
    consensus, and in particular when, for example, in this
    discussion when we change dramatically what a lot of people
    have held true, that is the Little Ice Age, Medieval Warming
    and so forth, and replace it with a flat curve very quickly, I
    do not think we have given it enough time to really decide if
    in fact that is an appropriate change in paradigm.
        Dr. Soon. Although I am not able to comment on anything on
    public policies, I am certainly able to testify that the
    science is completely unsettled. There are just so many things
    that we do not know about how the climate really works and what
    are the factors that cause it to change, to really jump to the
    conclusion that it will all be CO2.
        Senator Thomas. Thank you. That helps a lot.
        [Laughter.]
        Senator Inhofe. You still have some time remaining. Did you
    have an opportunity to see the chart up here that Dr. John
    Reilly, MIT Joint Program on Science Policy and Global Change?
    On the floor yesterday, I talked at some length on this. There
    seems to be a lot of consensus that there are some very
    positive benefits.
        Senator Thomas. It is really interesting, you know, in
    Schlesinger's thing it indicates that the temperature after
    1940 dropped until 1977. So that makes you wonder what we ought
    to do. The rise in temperature during the 20th century occurred
    between 1900 and 1940. So now we are faced with making policy
    decisions where there is no real evidence that the things that
    the greenhouse gases measurable by the U.N. is the basis for
    doing these things.
        I know in science everyone has little different ideas, but
    I do think we are going to have to, Mr. Chairman, as you
    pointed out yesterday, either take it a little more slowly in
    terms of policy, or we are not going to have something more
    basic to base it on than we have now in order to make
    significant policy changes.
        Thank you.
        Senator Inhofe. Thank you, Senator Thomas.
        Senator Carper.
        Senator Carper. Thank you, Mr. Chairman. I want to welcome
    our witnesses this morning. Dr. Legates, it is great to have a
    fighting Blue Hen here from the University of Delaware. We are
    delighted that you are here. Dr. Mann, thanks for coming up,
    and Dr. Soon, welcome. We thank you for your time and your
    interest and your expertise on these issues, and your
    willingness to help us on some tough public policy issues that
    we face.
        Dr. Mann, I would start off if I could and direct a
    question to you. I understand we have had thermometers for less
    than 200 years, and yet we are trying to evaluate changes in
    temperature today in this century and the last century with
    those that occurred 500 or 1,000 or 2,000 years ago. I
    understand that we use proxies for thermometers, if you will,
    and for those kinds of changes in temperature.
        I wonder if you could help me and maybe the committee
    better understand how we compare today's temperature
    measurements to the proxies of the past. Are there potential
    risks with relying on some of those proxies?
        Dr. Mann. Absolutely. We have to use them carefully when we
    try to reconstruct the past temperature history. So when I say
    we have to use them carefully, it means some of the things that
    I discussed in my testimony earlier, that we need to actually
    verify that if we are using a proxy record to reconstruct past
    temperature patterns, that proxy record is indeed reflective of
    temperature changes. That is something that typically
    paleoclimate scientists first check to make sure that the data
    they are using are appropriate for the task at hand. Of course,
    we have done that in our work. I did not see evidence that Soon
    and colleagues have done that.
        First of all, we next have to synthesize the information.
    There have been some misleading statements made here earlier on
    the part of the other testifiers with regard to local versus
    regional or global climate changes. Of course, we have to
    assimilate the information from the local scale to the larger
    scales, just as we do with any global estimate of quantity. So
    we take the regional information; we piece together what the
    regional patterns of change have been, which may amount to
    warming in certain areas and cooling in other areas. Only when
    we have reconstructed the true global or hemispheric regional
    patterns of change can we actually estimate the northern
    hemisphere average, for example.
        A number of techniques have been developed in the climate
    research community for performing this kind of estimate. My
    colleagues and I have described various statistical approaches
    in the detailed climate literature. Some of the estimates are
    based on fairly sophisticated techniques. Some of them are
    based on fairly elementary techniques. Yet all of the results
    that have been published in the mainstream climate research
    community using different techniques and different assortments
    of proxy data have given, as I showed earlier in my graph, the
    same basic result within the uncertainties. That has not
    changed. An article that appeared last month in the American
    Geophysical Union, which is actually the largest professional
    association of climatologists, showed that indeed that is the
    consensus viewpoint of the climate research community.
        Senator Carper. Thank you.
        Dr. Legates, if I could ask a question of you, please. Have
    you or anyone of your colleagues, at the University of
    Delaware, to your knowledge studied the historical climate and
    temperature records in our part of the country, in Delaware,
    the Delmarva Peninsula, or the mid-Atlantic region?
        Dr. Legates. We do not have anybody on staff presently that
    does paleoclimatology. One of the basic understandings that you
    must come up with when you study climate is that you must
    understand various things of hydroclimatology, physic
    climatology, and that includes paleoclimate study. So you must
    be at least versed in these things if you are not necessarily a
    paleoclima-
    tologist.
        We do have Dr. Brian Hanson at the University of Delaware
    who has looked at glacier movements over long time periods, as
    well as Dr. Fritz Nelson who has looked at changes associated
    with permafrost locations.
        Senator Carper. If someone were to do a study for our part
    of the country, what do you think they might find?
        Dr. Legates. A study regarding?
        Senator Carper. Historical climate and temperature changes.
        Dr. Legates. Over the East Coast of the United States? Most
    of the assessments indicated that generally the East Coast has
    gone through a variety of changes over long time periods.
    Historically, we have had a condition where in the 1960's, for
    example, we had conditions where there was much more snowfall.
    We have had a lot of variability associated with air
    temperature rising and falling over the local conditions.
    Variability is usually the characteristic of climate over the
    near-term as well.
        Senator Carper. OK. Dr. Soon, if I could ask you and maybe
    Dr. Legates the same question, the following question. That
    question is, do you believe that it is possible to emit
    unlimited amounts of CO2 into our atmosphere without
    having any impact on climate or temperature?
        Dr. Soon. I do not know how to precisely answer the
    question. If you fill up every single molecule of the air with
    CO2, that would be poisonous, of course. I do not
    know the answer to the question, but I do like to add about the
    evidence available on climate change.
        Senator Carper. Before you do that, let me direct, if I
    could, the same question to Dr. Legates. I do appreciate your
    candor. It is not everyday that we find that here in this hall.
        Dr. Legates. Generally, what we have found is that as
    carbon dioxide has increased, the temperature has followed,
    where in some cases historically the temperature has gone up
    and the carbon dioxide has fallen. So generally from a purely
    physical point of view, if you do increase the carbon dioxide,
    you should wind up with some trapping of gases, and hence wind
    up with a slightly increased temperature.
        The question is, there is a lot of additional feedbacks
    associated with it. For example, warmer surface temperature
    leads to more instability or rising air which leads to more
    cloudiness. Clouds can warm at night, but also reflect energy
    in the daylight. So you have these odd playbacks into the
    climate system which make it very difficult to say that if I
    hold everything else constant and change one variable, what
    will happen. Well, in reality, it is impossible to hold
    everything constant because it is a very intricate and
    interwoven system that one change does have feedbacks across
    the entire spectrum.
        Senator Carper. Thanks. I think my time has expired, Mr.
    Chairman. Is that correct?
        Senator Inhofe. Yes. Thank you, Senator Carper.
        Senator Carper. Thank you.
        Senator Inhofe. We will have another round here. In fact, I
    will start off with another round. Let's start with Dr.
    Legates. Dr. Legates, was the temperature warmer 4,000 to 7,000
    years ago than it is today?
        Dr. Legates. My understand was during about 4,000 to 7,000
    years ago, in a period referred to as the climatic optimum,
    which sort of led to enhanced agriculture and led to
    development of civilization, generally the idea is that warmer
    temperatures lead to more enhanced human activity; colder
    temperatures tend to inhibit. Again, as we get back 4,000 to
    7,000 years ago, it becomes, the error bars are getting wide as
    well. But the general consensus is that temperatures were a bit
    warmer during that time period.
        Senator Inhofe. OK. Senator Thomas had something about, he
    had alluded to 1940. Yesterday when I was giving my talk and
    doing the research for that, it was my understanding that the
    amount of CO2 emitted since the 1940's increased by
    about 80 percent. Yet that precipitated a period of time from
    about 1940 to 1975 of a cooling-off period. Is that correct?
        Dr. Legates. That is correct. It is sort of a perplexing
    issue in the time series record that from 1940 to 1970
    approximately, while carbon dioxide was in fact increasing,
    global temperatures appear to be decreasing.
        Senator Inhofe. Dr. Mann, you have I might say impugned the
    integrity of your colleagues and a few other people during your
    presentation today. The Wharton Econometric Forecasting
    Associates did a study as to the effect of regulating
    CO2 and what would happen. American consumers would
    face higher food, medical and housing costs; for food, an
    increase of 11 percent; medicine, an increase of 14 percent;
    and housing, an increase of 7 percent. At the same time, the
    average household of four would see its real income drop by
    $2,700 in 2010.
        Under Kyoto, the energy and electricity prices would nearly
    double and gasoline prices would go up an additional 65 cents a
    gallon. I guess I would ask at this point, what is your opinion
    of the Wharton study?
        Dr. Mann. OK. First, I would respectfully take issue with
    your statement that I have impugned the integrity of the other
    two testifiers here. I have questioned their, and I think
    rightfully, their qualifications to state the conclusions that
    they have stated. I provided some evidence of that.
        Senator Inhofe. Well, ``illegitimate, inexperienced,
    nonsense''----
        Dr. Mann. Those are words that I used. Correct.
        Senator Inhofe [continuing]. That is a matter of
    interpretation.
        Go ahead.
        Dr. Mann. I would furthermore point out that the very
    models that I have referred to track the actual instrumental
    warming and the slight cooling in the northern hemisphere.
    There was no cooling of the globe from 1940 to 1970, the
    northern hemisphere----
        Senator Inhofe. OK. The question I am asking you is about
    WEFA.
        Dr. Mann. I am not a specialist in public policy and I do
    not believe it would be useful for me to testify on that.
        Senator Inhofe. Dr. Legates, have you looked at the report
    that Wharton came out with concerning the possible effects,
    economic results of this?
        Dr. Legates. Again, I am not a public policy expert either,
    and so the economic impacts are not something which I would be
    qualified to testify on.
        Senator Inhofe. OK, Dr. Legates, do you think you have more
    data than Dr. Mann?
        Dr. Legates. I think we have looked at a large variety of
    time series. We have looked at essentially a large body of
    literature that existed both prior to Dr. Mann's analysis and
    since Dr. Mann's analysis, in attempting to figure out why his
    curve does not reflect the individual observations. It is one
    issue associated with when you put together data sets, to make
    sure that the composite sort of resembles the individual
    components.
        Senator Inhofe. OK. The timeline, Dr. Mann, is something I
    have been concerned with, and those of us up here are listening
    to you and listening to all three of you and trying to analyze
    perhaps some of the data that you use and the conclusions you
    came to, having been 4 or 5 years back, compared to a study
    that was done referring to Smithsonian-Harvard, the 1,000-year
    study that was just completed, or at least given to us in March
    of this year. I would like to have each of you look at the
    chart up here and just give us a response as to what you feel
    in terms of the data that both sides are using today.
        Dr. Mann. I guess you referred to me first?
        Senator Inhofe. That is fine. Yes.
        Dr. Mann. OK. Well, I think we have pretty much
    demonstrated that just about everything there is incorrect. In
    a peer-reviewed publication that was again published in the
    Journal Eos of the American Geophysical Union about a month
    ago, that article was cosigned by 12 of the leading United
    States and British climatologists and paleoclimatologists. We
    are already on record as pretty much pointing out that there is
    very little that is valid in any of the statements in that
    table. So I think I will just leave it at that.
        Senator Inhofe. Do the other two of you agree with that?
        Dr. Legates. If I may add, the Eos piece was actually not a
    refereed article. It is an Eos Forum piece, which by definition
    is an opinion piece by scientists for publication in Eos. That
    is what is contained on the AGU Web site for Eos Forum.
        Senator Inhofe. All right. Let me ask one last question
    here. Dr. James Hansen of NASA, considered the father of global
    warming theory, said that the Kyoto Protocol ``will have little
    affect on global temperatures in the 21st century.'' In a
    rather stunning followup, Hansen said it would take 30 Kyotos,
    let me repeat that, 30 Kyotos to reduce warming to an
    acceptable level. If one Kyoto devastates the American economy,
    very much by the findings of Wharton, what would 30 Kyotos do?
    Is Dr. Hansen one of the most respected scientists in your
    field or is he way off base?
        Dr. Mann. Dr. Hansen is certainly one of the most respected
    scientists in my field and I personally have great scientific
    respect for him. I think that his conclusions have been grossly
    taken out of context. His point is simply that Kyoto would, and
    this is his point, these are not my opinions, would do very
    little to ameliorate the warming over the next century for two
    reasons.
        No. 1, there is something that scientists call the
    commitment to warming. Once we put CO2 into the
    atmosphere, it takes many decades, on orders of decades to
    maybe centuries for it fully to equilibrate with the ocean and
    the atmosphere. So some of that CO2 is taken up by
    the ocean. So the effect of it is delayed. So cutting back on
    CO2 now may not affect global temperatures for 50
    years, but 50 years later it is going to come back to roost.
        Senator Inhofe. All right, that was a rather long answer,
    so let me just, with the indulgence of my fellow Senators here,
    I just want to ask one last question. I quoted Dr. Frederick
    Seitz, the past president of the National Academy of Sciences
    yesterday, and professor emeritus at Rockefeller University,
    who compiled an Oregon petition which says there is no
    convincing scientific evidence that human release of carbon
    dioxide, methane and other greenhouse gases is causing, or will
    in the foreseeable future cause catastrophic heating of the
    Earth's atmosphere and disruption of the Earth's climate.
        Moreover, there is substantial scientific evidence that
    increases in atmospheric carbon dioxide produce many beneficial
    effects upon the natural plant and animal environments of the
    Earth. Do each of the three of you agree or disagree with his
    statement?
        Dr. Soon. I agree.
        Dr. Mann. I find little in there to agree with.
        Dr. Legates. I would tend to agree.
        Senator Inhofe. All right.
        Senator Jeffords.
        Senator Jeffords. As you may know, this is to all of you,
    the editor-in-chief of the magazine Climate Research resigned
    the position yesterday over problems with Dr. Soon's paper. In
    an e-mail sent to my staff, he said,

              ``My view, which is shared by many, but not all editors and
            review editors of Climate Research, is that the review of the
            Soon et al paper failed to detect significant methodological
            flaws in the paper. The critique published in the Eos journal
            by Mann et al is valid. The paper should not have been
            published in this forum, not because of the eventual
            conclusion, but because of the insufficient evidence to draw
            this conclusion.''

        What methodological flaws does he mean?
        Dr. Mann.
        Dr. Mann. Well, I have tried to outline the most severe of
    those methodological flaws. I believe it is the mainstream view
    of just about every scientist in my field that I have talked to
    that there is little that is valid in that paper. They got just
    about everything wrong. They did not select the proxies
    properly. They did not actually analyze any data. They did not
    produce a reconstruction. They did not produce uncertainties in
    a reconstruction. They did not compare to the proper baseline
    of the late-20th century in trying to make conclusions about
    modern warmth.
        So I think it is the collective view of our entire research
    community that that is one of the most flawed papers that has
    appeared in the putative peer-reviewed research in recent
    years.
        Senator Jeffords. Dr. Soon, do any scientists besides your
    coauthors support using wetness or dryness as indicators of
    past temperatures, instead of actual temperatures or proxy data
    that reflects temperatures?
        Dr. Soon. As we explain clearly in our paper, and as it has
    been highly mischaracterized by my fellow colleague here, Dr.
    Mann, we certainly agree when we speak in term of the Medieval
    Warm Period, temperature is one of the important parameters. As
    we emphasize and specify in our papers that climate is not
    temperature alone. One has to look in terms of the water cycle,
    in terms of even the air cycles, in terms of the vegetation
    changes. These are the kind of details that we did not make any
    presumptions, but simply want to look at the patterns of change
    geographically all over the world, and see how complete the
    datas are, and then begin to start to see how do we assemble
    all such information.
        Senator Jeffords. This is for the whole panel. I would like
    to know whether the unusual melting of Greenland ice sheets
    shown in this picture over the years 2001, 2002 and 2003, has
    been matched in the long-term climate history any other time?
    And according to NASA, by the end of the year 2002 season, the
    total area of surface melt in the Greenland ice sheet had
    broken all known records. By the end of that summer ``Sea ice
    levels in the Arctic were the lowest in decades and possibly
    the lowest in several centuries.''
        NASA says this warming is happening faster and earlier than
    in previous periods. What is happening now and what is going to
    happen if this continues?
        Dr. Mann.
        Dr. Mann. Well, this is, of course, one particular region,
    one potentially isolated region, Greenland, in which there is
    evidence of mass oblation of ice. But if we look at what is
    going on the world over, mountain glaciers in the tropics
    throughout the world, glaciers in both the northern hemisphere
    and the southern hemisphere, what is seen is that glacial
    retreat during the late 20th century is unprecedented on
    similar time scales to the time scales I have spoken of before,
    the past 1,000 to 2,000 years.
        I believe Professor Lonnie Thompson of Ohio State
    University has testified in this Senate before with regard to
    the dramatic evidence of worldwide glacier retreat. So that is
    a cause for concern. It is a harbinger of the warming because
    in fact the warming that is shown in those glacier retreats is
    actually warming that we are already committed to for decades
    to come.
        Dr. Legates. Historically, it has been demonstrated in the
    refereed literature that much of this glacial retreat actually
    began in the late 1800's, before much of the carbon dioxide
    came into the atmosphere. This is very much consistent with the
    demise of the Little Ice Age and longer time-scale variations.
    Therefore, it is very difficult to say that these kind of
    events are directly attributable to human impacts on the
    climate, when they in fact pre-date human impacts on the
    climate.
        Senator Jeffords. Dr. Soon.
        Dr. Soon. My only comment regarding that kind of chart or
    the claim that it has never happened before is that to think
    about the available, detailed observation that we have. We do
    not really have any satellite record longer than 20 to 30
    years, so the statement that it has never happened before I
    think is dangerously inaccurate.
        Senator Jeffords. Dr. Mann.
        Dr. Mann. Yes. It is unfortunate to hear comments about the
    supposed inconsistencies of the satellite record voiced here,
    years after that has pretty much been debunked in the peer-
    reviewed literature, in Nature and Science. Both journals have
    in recent years published several rigorously peer-reviewed
    articles indicating that in fact the original statement that
    the satellite record showed cooling was flawed because the
    original author, John Christy, did not take into account a
    drift in the orbit of that satellite, which actually leads to a
    bias in the temperatures from the satellite.
        Christy and colleagues have claimed to have gone back and
    fixed that problem, but just about every scientist who has
    looked at it says that their fix is not correct. If you fix it
    correctly, then the satellite record actually agrees with the
    surface record, indicating fairly dramatic rates of warming in
    the past two decades.
        Senator Jeffords. I have one last question, Dr. Mann. What
    are the implications of your peer-reviewed work for future
    manmade warming?
        Dr. Mann. As I said before, there have been a number of
    modeling simulations that have shown a fairly good match to our
    reconstruction and that of several independent research groups
    who have also produced these reconstructions of northern
    hemisphere temperature. So to the extent that the models match
    that record of the past 1,000 years when they are forced with
    various estimates of natural changes in the system, it gives us
    reason to trust what the models say about the future. As I
    testified before, the models tell us that we are likely to see
    a one degree to four degree Fahrenheit warming by the mid-20th
    century, given most predicted scenarios of continued
    anthropogenic influence on the climate.
        Dr. Legates. If I may add something, one of the things I
    have heard is that science has been debunked and, for example,
    we pointed to Dr. Christy's curve up here and said that because
    one paper has been written, that curve is now called into
    question. We have talked about--you mentioned von Storch's
    resignation from Climate Research because apparently he has
    admitted that this paper never should have been published.
        I want to point out that science debate goes on and on. In
    particular, Dr. Christy has had some very important
    contributions to indicate that his curve is not incorrect. That
    is part of scientific debate. Furthermore, I will say with
    respect to Climate Research, Otto Kinne, who is director of
    Inter-Research, the parent organization of Climate Research,
    asked Chris de Freitas who was the editor who served on the
    Soon and Baliunus papers, and I can relay this because I am a
    review editor of Climate Research so I am familiar with what
    has been taking place.
        There were several people complaining that Chris de Freitas
    should be removed simply because he published the Soon and
    Baliunus paper. That question was brought to Otto Kinne. He
    asked for Chris de Freitas to provide him with the reviews, the
    changed manuscripts and so forth. He provided a letter in late
    June to all of us in which he said,

              ``I have reviewed the evidence and I have indicated that the
            reviews, four for each manuscript, in fact there was a second
            or an earlier Soon and Baliunus article on another topic that
            was also called into question by these people leveling
            charges.''

        Essentially what he concluded was that the reviewers
    provided good and appropriate comments; that Doctors Soon and
    Baliunus provided an appropriate dressing or incorporation of
    these concerns; and that Chris de Freitas had in fact provided
    analysis appropriately.
        Toward that end, Dr. von Storch was approached. Climate
    Research was putting in an editorial stating essentially this
    article should never have been published. Otto Kinne was
    informed and he has asked him not to submit that because it is
    not founded, and as a result Dr. von Storch, I now understand,
    has said he would resign.
        Senator Jeffords. Dr. Mann.
        Dr. Mann. Yes, just a very short comment. It is
    unprecedented in my career as a scientist to hear of a
    publisher of a journal going in and telling the editor-in-chief
    that he cannot publish an editorial. I find that shocking and a
    bit distressing. I do not know what the circumstances are
    behind it, but it is disturbing.
        Dr. Legates. It is also unprecedented to find an editor
    being attacked, and this has also happened with the editorial
    staff of Energy and Environment, which is the other paper, to
    find an editor attacked for simply publishing an article that
    has been peer-reviewed and approved by reviewers.
        Senator Inhofe. All right. The time has expired. We are 4
    minutes over.
        Senator Jeffords. I think that my witness should have the
    last word on my question, if I could. Dr. Mann, do you have any
    response to that?
        Dr. Mann. Actually, my understanding is that Chris de
    Freitas, the individual in question, frequently publishes op/ed
    pieces in newspapers in New Zealand attacking IPCC and
    attacking Kyoto and attacking the work of mainstream
    climatologists in this area. So this is a fairly unusual editor
    that we are talking about.
        Senator Inhofe. All right, thank you.
        Senator Clinton has joined us. Senator Clinton would you
    like to have your round now?
        Senator Clinton. Thank you very much, Mr. Chairman. I thank
    you for this hearing. I understand that the questioning and the
    testimony has been somewhat lively, if not controversial and
    contested. The bottom line for me is whether we are doing what
    we need to do to ensure the best possible climatology outcome
    for future generations. I would stipulate that the Earth's
    climate has changed through the millennia. There is no doubt
    about that. I have read enough to know that we have had ice
    ages and we have had floods and we have had volcanoes. We have
    had lots of naturally occurring events which have affected our
    climate. We have El Nino and his spouse, El Nina. We have all
    of that. That is not debatable.
        The issue is whether the introduction and acceleration of
    anthropogenic activity primarily related to the burning of
    fossil fuels is putting into place conditions that will make it
    difficult, if not impossible for the Earth to regain its
    balance, that will support the conditions of life that we have
    inherited and are blessed with.
        I know these debates have political implications because
    heaven forbid that we would tell somebody in the private sector
    not to do something, or that we might have to make sacrifices
    in the quality of our life for future generations. I think that
    it is not useful to carry out this kind of argumentation when
    it is clear that by the very nature of human development and
    industrialization, we have changed what is in the atmosphere,
    what is in the earth, what is in the waters.
        That does not mean there was no change before we came
    along, and certainly in the last century that change has
    accelerated because the quality of life has improved, we have
    created chemicals that were never known in nature before. We
    have done a lot of things.
        But I think that our goal should be to try to figure out
    how to do no harm or do the least amount of harm, and to ask
    ourselves, what are we willing to perhaps sacrifice to make
    sure that we are not contributing to irreversible changes. I
    know that academia is probably the most political environment
    in America. I was once on a staff of a law school. It was more
    difficult than any politics I had ever been involved in
    beforehand. I know that people have very strong opinions and
    hold on to them.
        From my perspective, I just want to believe that I am
    making a contribution to ensuring that the quality of life for
    future generations is not demonstrably diminished. I would feel
    terrible if I participated, either as a willing actor or a
    bystander, in this potential undermining of our Earth's
    sustainability.
        So Dr. Mann let me ask you, what was the Earth's climate
    like the last time that there was atmospheric concentration of
    carbon dioxide at today's levels of 370 parts per million?
        Dr. Mann. Thank you, Senator, that is an excellent
    question. We have to go back fairly far into the past to find
    CO2 levels approaching the CO2 levels
    today. Ice core studies that have been done over the past
    decade or so have told us that today's CO2 level is
    unprecedented now in at least four glacial or inter-glacial
    cycles. That is more than 400,000 years.
        In fact, now as we look back from other evidence that is a
    bit more tentative, it appears that modern CO2
    levels probably have not been observed in 10 million to 20
    million years. So we have to go back to the time of the
    dinosaurs, probably, to find CO2 levels that we know
    were significantly higher than CO2 levels today.
        Some people will say, ``Well look that was a great time.''
    The dinosaurs were roaming near the poles. It was warm near the
    north pole. There were palm trees in the poles. Isn't that what
    we want? Well, that was a change that occurred on time-scales
    of tens of millions of years. What we are observing right now
    is a similar change that is occurring on time-scales of
    decades.
        Senator Clinton. Thank you. Thank you, Dr. Mann.
        Senator Inhofe. Senator Clinton, if you would like to have
    some more time, since we are on the second round now, feel free
    to take another couple of minutes.
        Senator Clinton. Thank you very much, Mr. Chairman.
        I guess that is, for me, the dilemma, because I certainly
    understand the testimony of the other two witnesses, and I read
    with great interest former Secretary Schlesinger's op/ed. I
    know that there are those, who are in a minority, let's at
    least admit that, who are in a minority, but who certainly have
    a very strongly held set of beliefs, and I respect that.
        But I do believe that the compression of time in which
    these changes are occurring is extraordinarily significant. We
    can go back and look at the Earth's natural 125,000-year cycle,
    but I do not think we want to risk the enormous changes that
    could occur. I do not think we have a million or 10 million
    years or even 100,000 to experiment.
        I think that the challenge confronting us is not to put our
    heads in the sand and let the academic argument take place, but
    figure out how in a sensible, prudent manner we could
    ameliorate these changes significantly enough so that if Dr.
    Soon and Dr. Legates are right, no harm done. If Dr. Mann is
    right, we will have saved ourselves a lot of potential damage
    and difficulty.
        So I hope that we could put our heads together. I commend
    my two colleagues, both Senator Jeffords and Senator Carper,
    who have very sensible legislative answers to trying to get a
    handle on this. As I have said in this committee before, I
    stand ready to figure out ways to hold harmless our industrial
    base and others. I think it is a significant enough political,
    economic and moral challenge that if there are ways to make it
    financially possible for companies to do what needs to be done
    with respect to carbon dioxide and other atmospheric pollutants
    that have accelerated their presence in our atmosphere so
    dramatically in the last 100 years, I think we should do that.
        This is not just a private sector problem. We all have
    benefited from the increasing use of fossil fuels, for example.
    Our standard of living is dramatically better. One of our
    problems is what is going to happen if China and India get a
    standard of living anywhere comparable to ours, and then begin
    to really--and I see Dr. Soon nodding--I mean really dump into
    the atmosphere untold amounts of new pollutants of whatever
    kind, leading certainly with carbon dioxide.
        So this is a problem we need to get ahead of, and it is not
    a problem that the United States alone should be responsible
    for. It is not a problem that the private sector alone should
    be responsible for. But I believe, just as a prior generation
    of decisionmakers really put a lot of work into the law of the
    oceans and trying to figure out how we could protect our
    oceans, we need to do the same on the atmospheric level. There
    has got to be a way that we can come together on this big
    challenge.
        So Mr. Chairman, I appreciate your continuing attention to
    this. I, for one, stand ready to work with you and our other
    colleagues because I just think this is too risky a proposition
    not to act on, given the weight of opinion, even with the
    dissenters, who I think do rightly point out the incredible
    natural cycle, but we are now so influencing that natural
    cycle, I do not know if we have the time to contemplate the
    balance once again regaining itself in our wonderfully
    regenerating Earth.
        Senator Inhofe. Thank you, Senator Clinton.
        Senator Carper.
        Senator Carper. Thanks, Mr. Chairman. I just want to
    followup. Senator Clinton was kind in her comments on the
    legislation, the one that Senator Jeffords has introduced and
    second on legislation I have introduced along with Senators
    Judd Gregg, Lincoln Chafee and Lamar Alexander.
        Are any of you familiar with that legislation? Would you
    like to become familiar over the next 5 minutes?
        [Laughter.]
        Dr. Soon. No, we will stick to science. Politics is too
    complicated.
        Senator Carper. All right. That may be the best approach.
        We are trying to figure out if there is a reasonable middle
    ground on this issue. I am part of a group that Buddy MacKay, a
    former colleague of mine from Florida, calls the flaming
    moderates or flaming centrists. We can spend a whole lot of
    time discussing the impact of Kyoto caps, or we can focus on
    what steps we actually need to take.
        The approach that Senators Gregg and Chafee and Alexander
    and myself have taken, at least with respect to four
    pollutants, we say unlike the President's proposal where he
    only addresses sulfur dioxide and nitrogen oxide and mercury,
    and does not address CO2, as you know, because he
    thinks we need to study it a bit more. Our approach says that
    there ought to be caps on CO2; that they should be
    phased in; that we should use a cap and trade system; we should
    give utilities the opportunity to buy credit for levels of
    CO2 emissions that they maintain at high levels; and
    they should be able to contract with, among others, farmers and
    those who would be forced out of lands to change their planning
    patterns or change their animal feedlot operations in order to
    be able to sequester some of the CO2 that occurs in
    our planet.
        We have something called new source review. The President
    would eliminate it entirely. I think in Senator Jeffords'
    approach, it is pretty much left alone. There is a good
    argument that says that utilities under current law, if they
    make some kind of minor adjustment and minor investment in
    their plant, that they have to make a huge investment with
    respect to the environmental controls. As a result, it keeps
    them from making even common sense kinds of investments in
    their plants--sort of the laws of unintended consequences. That
    is sort of the approach that we have taken.
        Now that you know all about it, if you were in our shoes,
    what kind of an approach would you take? Let me just start with
    our University of Delaware colleague here, Dr. Legates.
        Dr. Legates. Generally, I favor no regrets policies, where
    they have other applications as well. But again, getting into
    the politics and the non-science aspects of what to do is out
    of my area of expertise. I may have my own beliefs, but they
    are no more important or less important than the average
    person. I would rather not testify to those here.
        Senator Carper. If you were convinced, and some of my
    colleagues have heard me talk about Dr. Thompson before, I
    don't know that they testified before this committee, but
    Doctors Knoll and Thompson spend their lives going around the
    world and they chart the disappearance of snow caps in some of
    the tallest mountains. I first met them here in Delaware about
    5 or 6 years ago to receive an award for their research.
        But they tell us that the snow caps around some of the
    tallest mountains in the world, the Himalayas and others, are
    not just disappearing, they will be gone, and they will be gone
    in our lifetime. When I heard them speak and talk about their
    work and what they were charting and finding, it got my
    attention. When you hear that, Dr. Legates and Dr. Soon, how
    does it affect you?
        Dr. Soon. As a scientist, I am still questioning the actual
    evidence. The fact is that meltings may be recorded for certain
    glaciers. But among the things that we know is that there are
    about 160,000 glaciers around the Earth, but only 40 to 50
    glaciers have been measured for 10 years or longer to tell us
    how much the ice has accumulated or has ablated.
        Some of the specific melting examples, like Kilimanjaro,
    that Dr. Lonnie Thompson has looked at, or some places in Peru
    may be true. But the quality of the data records is really
    telling us that we do not have enough strong evidence to
    suggest that all the ice will disappear quickly and completely,
    or that all of it is unprecedented. Climate change is part of
    nature. As I tried to emphasize in my research by looking
    carefully into all the climate proxies, there are large local
    swings in the climatic changes.
        Senator Carper. Dr. Soon, what would it take to convince
    you that this is a problem we need to deal with?
        Dr. Soon. As to some of the glaciers disappearing now in
    some parts of the mountains, I do not consider that to be
    either a problem or strong evidence----
        Senator Carper. No, no, the big issue. What would it take
    with respect to the concerns about global warming fed by
    CO2 accumulation, what would it take to convince you
    that this is a problem we need to do something about?
        Dr. Soon. OK. Scientifically, I would go by this very
    simple test. The simple test should be that the warming should
    be occurring first at the troposphere, the layer of air about
    four kilometers above us. That is a key part of the atmosphere
    that one should expect the CO2 greenhouse effect to
    work its way downward toward the surface. I would urge, of
    course, very seriously that we do not lose sight in all these
    debates about science, we must sustain a certain kind of level
    of observational effort to keep track of data so that while we
    are arguing around what to do, that one has some records about
    any level of change that may occur.
        So what it would take is that the CO2 warming
    should happen at the layer of air four kilometers first. I
    would require it be strongly sustained for maybe 20 years or
    so. Then I would really believe that we have clear
    CO2 fingerprints somewhere.
        Senator Carper. Mr. Chairman, I know my time has expired.
    Could I just ask that same question of Dr. Legates? What would
    it take to convince you?
        Dr. Legates. Proof. Generally the problem we have seen in
    the record is that there is an awful lot of variability and
    there are things where changes occur, for example, between 1940
    and 1970 where the temperature decreased, even though carbon
    dioxide was increasing. That sort of indicates to me that
    carbon dioxide may not be the biggest player in the game. Solar
    variability is likely to be the bigger player, changes in solar
    output. After all, if the sun goes out, our temperature drops
    considerably. We know historically that as the sun fluctuates
    in terms of its output, the climate does respond.
        So there are a lot of other factors involved and I am not
    entirely convinced, based upon the proof, that carbon dioxide
    is a driving force. It is a contributory force in a small case,
    but not driving enough, because we wind up making policies
    potentially that can lead us to try to keep back the ocean, if
    you will. You cannot stop the waves from coming in.
        Senator Carper. Dr. Mann.
        Dr. Mann. Two quick points. First of all, it grates on me
    to hear this argument about cooling from 1940 to 1970
    continually cited here as evidence against anthropogenic
    climate change. That cooling was almost certainly anthropogenic
    and there has been a decade of research demonstrating that,
    anthropogenic sulphate aerosols, which have a cooling effect on
    the climate. What is happening now is that the much greater
    effect of increasing greenhouse gas concentrations is
    overtaking that small cooling effect of sulphate aerosols, also
    an anthropogenic influence, but not the one that is going to
    take us to doubled levels of CO2 in the next
    century.
        One quick other comment, if I could. Lonnie Thompson's
    work, which is some of the best work in our field, it is not
    like he has been looking for ice cores that are melting. He is
    actually looking for ice cores that are not melting because he
    wants to get long records. So if there is any belief that there
    might be some bias in the glaciers that he has gone to, if
    anything it is the opposite. He is looking for long records, so
    that makes it that much more impressive that they are all
    melting.
        Senator Carper. Thank you.
        Senator Inhofe. Senator Allard.
        Senator Allard. Thank you, Mr. Chairman.
        What agency do you think we probably have the most
    expertise in as far as climatology change and what is happening
    with global climate? Would that be the agency on the National
    Oceanographic and Atmospheric Science, would that probably be
    where we would have most of our experts? If not, which agency
    do you think we would have most of our experts as far as the
    government is concerned? To any member of the panel, I would
    like to know whether any of you concur or not.
        Dr. Mann. Well, I think that the different agencies
    specialize in different areas of the climate change research
    question, if you will. NOAA's specialty is in looking at
    climate variability, particularly with regard to oceanic
    variability. So they emphasize that area of the research. A lot
    of the peer-reviewed research, for example Lonnie Thompson's
    work that we just spoke of, is funded by the National Science
    Foundation in large part. There are other organizations.
        Senator Allard. The Foundation, is that an agency of the
    Federal Government?
        Dr. Mann. Well, not directly.
        Senator Allard. The question is, what is an agency of the
    Federal Government? The only one that I could think of was
    NOAA, but are there other agencies?
        Dr. Legates. NASA does a lot of research, satellite-related
    efforts trying to estimate climate trends, incorporating
    satellite measurements as well.
        Dr. Mann. As well as the Department of Energy and EPA.
        Senator Allard. Yes, the Department of Energy.
        Dr. Legates. The Department of Interior as well.
        Senator Allard. OK. But we do not have any, say, each
    agency would have their own area of interest, but it seems to
    me that we need to look at global warming from a total
    perspective and I am trying to figure out if there is an agency
    that does that. I have talked to people within NOAA. There are
    arguments going on within that agency on the very topic that we
    are talking about here. There is absolutely no consensus within
    the agency, and I am trying to figure out if there is an agency
    out here that is taking on an overall view. I guess really
    there is not. We are just going to have to rely on the science
    community somehow or the other pulling all these views out from
    these various agencies. They look at the atmosphere, like you
    say, NASA looks at the stratosphere and higher up where your
    satellites are.
        Dr. Legates. On the surface, too.
        Senator Allard. We need somebody that looks at the effect
    on plant life, animal life, the total cycle; oxygen,
    CO2 and all that before you reach conclusions. I am
    just wondering who pulls all this together so that we can come
    up with a total picture of what is happening as far as changes
    to this Earth is concerned, because it is more than just one
    science.
        Dr. Mann.
        Dr. Mann. There is a program, the U.S. Global Change
    Research Program, which seeks to coordinate the various
    agencies on issues of fundamental importance in the research of
    climate variability and climate change. So I think that is
    their role.
        Senator Allard. OK. I want to get back a little bit to the
    absorption of sunlight, for example, on the Earth's surface. It
    seems to me, and I don't know how accurate this is. I want to
    check this out because it has been suggested to me by a number
    of people, that our absorptive surface on the Earth has
    increased. We still have the same amount of surface, but for
    example you have pavement in urban areas. We know that pavement
    is absorptive. Has that had an impact on global warming?
        Dr. Mann. Most definitely.
        Senator Allard. In your view?
        Dr. Mann. Yes, your statement is correct. The main increase
    in the absorption by the Earth's surface is due to the melting
    of snow and ice. That has certainly had a very large influence
    on the warming, but it is part of the warming.
        Senator Allard. So you do not think the construction of--we
    have more pavement than we did two centuries ago or a century
    ago.
        Dr. Mann. Most models suggest that that is a cooling.
        Senator Allard. Is there enough of that that we have more
    fields probably because of agriculture throughout the world,
    just not the United States. This is all over the world.
        Dr. Mann. Yes. Most estimates suggest that there is a small
    cooling of the Earth's surface due to those changes.
        Senator Allard. Would you all agree to that?
        Dr. Legates. The pavements are associated with the
    urbanization effect, which is part of the problem associated
    with where we have observational measurements. Generally where
    you have a decrease in the light and heat exchange that is
    evaporation of water taking place because we have removed
    trees; the fact that you have darker surfaces; you have canyon-
    like effects. All of these lead to warmer temperatures in the
    city. The urban heat ion effect is well-documented and that is
    where virtually all of our observations are located.
        But there are also changes in land surface effects by the
    fact that we are removing vegetation and replacing it with
    grasslands, for example, deforestation, de-vegetation. A lot of
    these are on very large-scales too, and they do change the
    color and character of the Earth's surface and hence the
    absorptive characteristic.
        A lot of the cryosphere, a lot of the ice and snow is
    temporally variable. We have a growing area and decreasing
    area, so that does integrate itself out over time to some
    extent.
        Senator Allard. Does the absorptive surface of the Earth's
    surface have an impact on whether we have a warmer temperature
    or not today?
        Dr. Legates. Yes, absolutely.
        Dr. Soon. Oh certainly, yes.
        Senator Allard. I am a little bit confused of what the
    final view is. Do we increase temperature or do we cool the
    temperature?
        Dr. Mann. Can I comment?
        Senator Allard. Yes. You said that it cooled.
        Dr. Mann. Yes, the effects that----
        Senator Allard. OK, now, I would like to hear from----
        Dr. Mann [continuing]. That is not the whole story. What he
    said is correct, but the effect that is dominant in models in
    about three or four different studies published in the past 2
    years on precisely this question is actually the change in
    absorption by the land surface due to deforestation and other
    agricultural changes. That leads to an overall cooling of the
    globe, even in the face of other possible effects of warming.
        Senator Allard. Would you agree with that?
        Dr. Legates. Not necessarily. In particular, you are
    changing a characteristic, but you are also changing the other
    interactions. You are changing the vegetation and you are
    changing the evaporative characteristics.
        Senator Allard. But your bottom line is that you think
    that, with increased absorptive rate on the Earth's surface, it
    has a cooling or a warming effect?
        Dr. Legates. If you increase the absorption rate on the
    Earth's surface, you will have to have a net warming effect.
        Dr. Soon. You have to have a warming.
        Senator Allard. You have a warming.
        I mean, to me this is a fairly fundamental concept, and
    here we are, we have disagreement at this table about that.
        Dr. Soon. I don't think Dr. Mann is listening to your
    question.
        Senator Allard. To me, from my practical experience, it
    seems to me that there is a warming effect. When I walk out on
    a pavement with my bare feet, they get burnt. If I walk on
    grass, my feet feel a lot cooler. I just look at it from a
    practical aspect. So Dr. Mann, would you explain to me why
    there is a difference in what you say and what I am feeling
    physically when I walk on the surface of the Earth?
        Dr. Mann. Sure. When you are walking, you are only covering
    a pretty small fraction of the surface area of the Earth. The
    effect that you are talking about, for example, the urban heat
    island effect of blacktop and its tendency to absorb heat, that
    is overwhelmed by larger-scale changes that we do not
    necessarily see because they are not where we are walking
    around. Large areas of the surface area of the Earth are being
    changed in terms of their vegetation characteristics. That has
    a net cooling. The answer on that is clear in the peer-reviewed
    research.
        Senator Allard. The reason I bring this up is that in the
    State of Colorado we have a lot of variation. We go from 3,000
    to over 14,000 feet and we have a lot of different ecological
    systems in Colorado, depending on altitude and moisture and
    everything.
        We have a weather reporting station in a rural area, in the
    plains of Colorado, and the data that I am getting from them,
    there is no indication of change as far as temperature is
    concerned. Yet as we move into the more urban areas, then we
    get weather stations that are indicating a higher temperature.
    So I am wondering worldwide, with the urbanization of the
    world, is there a possibility that we could be dealing with
    some temperature changes that are a result of the absorptive
    surface on the Earth like urbanization, you mentioned
    urbanization, we have a lot more than we used to have. Doesn't
    this have an impact on temperature?
        Dr. Legates. Yes, definitely. Essentially, I do not think
    Dr. Mann answered the question appropriately in that your basic
    question was, if we absorb more radiation at the surface, will
    the temperature not go up? That is correct. The temperature
    will go up. In a sense, that is physics.
        Senator Allard. Would you agree with that, Dr. Mann?
        Dr. Mann. No. He has gotten about three different things
    wrong here.
        Senator Allard. No, listen.
        Dr. Mann. His first statement is wrong.
        Senator Allard. I understand your statement. You are taking
    a broader atmospheric picture. You are taking a total picture.
    But the statement he made at this point, would you agree with
    that?
        Dr. Mann. No. It is not correct.
        Senator Allard. You would not agree?
        Dr. Mann. The statement that he made was that there is an
    urban heat bias in the estimate of the surface temperature
    changes of the Earth.
        Senator Allard. I did not hear him say that.
        Dr. Mann. He said that earlier when he talked about urban
    heat bias.
        Senator Allard. I am talking about the comment that he just
    made. Would you repeat the comment, Dr. Legates?
        Dr. Legates. I essentially said the basic physics is that
    if you make the Earth's surface darker, you will absorb more
    energy, you will reflect less energy, as a result the surface
    temperature should increase.
        Senator Allard. Would you agree with that scientific fact?
        Dr. Mann. That statement would be in the first chapter of
    most textbooks. Yes.
        Senator Allard. Dr. Soon, I did not mean to ignore you. You
    wanted to say something?
        Dr. Soon. I tried to just emphasize that that is all you
    are asking.
        Senator Allard. Yes.
        Dr. Soon. If you increase absorptivity of the surfaces by
    changing it through any means, then more heat will be retained.
        Senator Allard. I think part of the problem that we are
    running into here on the testimony is that we are not talking
    on the same terms. I think that we have to be very careful when
    we review the record and when we are listening to the witnesses
    here, Mr. Chairman, that we understand that we are all talking
    on the same terms in making the same point. I think the
    committee gets confused when we start talking from different
    terms and different perspectives.
        I am just trying to simplify this argument down. I guess
    what I am coming to is that, as I have stated earlier, it is
    easy for me to believe that there is a trend in warming. The
    bottom line is what is causing it and what is going to be the
    long-term effects with this.
        To me, the science is not entirely clear on that, and I do
    not see that that is being entirely clear on this panel because
    when I asked that question earlier, nobody gave me a specific
    on what they saw the effects were going to be. Maybe Dr. Mann
    did, and said that there was going to be warming. But most
    scientists when I talk to them just won't give me what they
    think the Earth is going to look like 1,000 years from now, or
    they will not necessarily step right out and say what are the
    causes of it because there are an awful lot of variables. I am
    not sure that scientists understand all those variables.
        Dr. Legates. I think that is the issue. It is so uncertain
    and there are so many things that go into the mix, that to say
    fairly definitively it will be such in the future is very
    difficult to say.
        Dr. Soon. We have to keep emphasizing that CO2
    is not the only player, the only factor. It is just highly
    short-sighted to just look at CO2 as just one sole
    cause of change for every other change that we see or any
    variations that we manage to record.
        Senator Allard. Yes. And when we talk about greenhouse
    gases, I think there is a tendency for us to think just in
    terms of CO2.
        Dr. Soon. Right.
        Senator Allard. But isn't water vapor? Water vapor is a big
    part of greenhouse gases.
        Dr. Soon. That would be the area of expertise by Professor
    David Legates. He studied that for almost 20 years.
        Senator Allard. I do not know as we understand all of the
    aspects of each one of those fractionated, if we were to pull
    out each CO2 or put out water vapor. What other
    gases do we have out there? Those are the main ones.
        Dr. Mann. The other two have commented. May I comment as
    well?
        Senator Allard. Let me finish my point. What are the
    greenhouse gases that we have?
        Dr. Mann. I will speak to that.
        Dr. Soon. Methane.
        Senator Allard. Oh, methane. OK. We have methane. But the
    main ones are water vapor and CO2. Water vapor being
    the largest, right?
        Dr. Soon. Yes.
        Dr. Mann. Can I comment on that?
        Senator Allard. Dr. Mann.
        Dr. Mann. Yes. There are trace gases like methane, carbon
    dioxide, chlorofluorocarbons, which we can actually control.
        Senator Allard. Well, carbon dioxide is a very small part
    of greenhouse gases? Is that what you are saying?
        Dr. Mann. No. There are several different greenhouse gases
    that we have to keep in mind, and it would be short-sighted to
    only talk about carbon dioxide. That is absolutely true.
        Senator Allard. Right.
        Dr. Mann. It is extremely misleading, however, when
    scientists cite the role of water vapor as a greenhouse gas.
    The concentration of water vapor in the atmosphere cannot be
    controlled by us directly, unlike the other trace gases. It is
    fixed by the surface temperature of the Earth itself. This is
    actually another chapter one textbook-type of result that we
    know to be true in the scientific community.
        So we cannot change that freely. We can only change the
    other trace gases. When we do change those, we warm the Earth.
    We evaporate more water vapor and that gives us what we call a
    positive feedback that actually exaggerates the problem. But
    the water vapor itself cannot be the source of the problem.
        Dr. Soon. It is really also scientifically inaccurate to
    say that we can really control CO2. The global
    carbon cycle--we do not understand it well enough to really
    match or account for the CO2 that we emitted. How
    much of it is really going into the ocean? How much of it has
    really gone into the forest? We do not have actually a full
    control of those parameters, as Dr. Mann would like to state on
    the record.
        Senator Allard. Dr. Legates, do you have any comment?
        Dr. Legates. Generally, the idea is that water vapor is the
    most important greenhouse gas. Period. That is Chapter One of
    any introductory text. The issue is, then, if we are
    associating with the effects of carbon dioxide and methane,
    which by the way has actually started to decrease over time,
    what we have found out is that in particular we are dealing
    with with small matters where the bigger issues are not
    controllable.
        Again, the sun is the biggest game in town and it is not
    controllable. At least I do not know that we can turn off the
    sun or control its output.
        Senator Allard. OK. Senator Carper I think has a few
    questions.
        Senator Inhofe. We have a serious problem here now, I am
    sorry to say, and that is that we are 30 minutes past our first
    panel and we are going to have to cut it off right now.
        Senator Allard. OK, Mr. Chairman.
        Senator Inhofe. I am very, very sorry. Thank you very much.
    I appreciate the fact that you are here.
        We would call our next panel up. I apologize to the next
    panel because of the length of the first panel, we will have to
    cut this one short.
        Dr. Leonard Levin is the program manager, Electric Power
    Research Institute; Dr. Gary Myers, professor of neurology and
    pediatrics, University of Rochester Medical Center; and Dr.
    Deborah Rice, the toxicologist, Maine Department of
    Environmental Protection, Bureau of Remediation and Waste
    Management.
        I would like to ask each of you to confine your opening
    comments to 5 minutes, if you would. Your entire statement will
    be made a part of the record. We would start, Dr. Levin, with
    you.

      STATEMENT OF LEONARD LEVIN, PROGRAM MANAGER, ELECTRIC POWER
                           RESEARCH INSTITUTE

        Dr. Levin. Thank you, Mr. Chairman, members of the
    committee.
        I am Dr. Leonard Levin. I have come to discuss recent
    findings on mercury in the human environment. I serve as
    technical leader at EPRI, which is a nonprofit collaborative
    research organization. My remarks today represent my synthesis
    of research findings and are not an official statement of EPRI
    position.
        It is a privilege to provide the committee this testimony
    on the science of mercury. I would like to address three key
    questions: sources of mercury; its deposition from the
    atmosphere to the Earth's surface; its potential accumulation
    in fish.
        Where does mercury in the U.S. environment originate?
    Mercury is clearly a global issue. Recent estimates are that
    2,340 tons of industry-related mercury are emitted globally.
    Over half of these originated from Asian sources. Of the global
    total, the United States is estimated to emit roughly 166 tons
    in total; U.S. utilities about 46 tons. In addition, it is
    estimated that another 1,300 tons of mercury emanates from
    land-based natural sources around the globe, and another 1,100
    or so tons comes from the world's oceans.
        Recent findings from the joint United States and Canadian
    METAALICUS field experiment show that a fairly small amount of
    deposited mercury, no more than 20 percent or so, re-admits to
    the atmosphere, even over a 2-year period. The implications are
    that mercury may be less mobile in the environment than we
    previously thought.
        Studies by EPRI have shown that much of the mercury
    depositing in the United States may originate on other
    continents. Model results show that for three-quarters of the
    continental U.S. land area, more than 60 percent of the mercury
    received comes from outside the country. Only 8 percent of U.S.
    territory receives two-thirds or more of its mercury from U.S.
    sources.
        To check this with data, aircraft measurements were carried
    out by EPRI and the National Center for Atmospheric Research in
    Boulder, Colorado. Mercury and winds from the Shanghai, China
    region were tracked over the Pacific for 400 miles toward the
    United States. A second set of flights from Monterey, CA found
    that same plume from China crossing the California coast and
    entering U.S. territory. One implication is that there may be a
    management floor for U.S. mercury, a level below which the
    amount of mercury depositing to the surface cannot be reduced
    by domestic action alone.
        Second, what are the primary sources of mercury in fish in
    the environment? Global mercury emissions appear to have peaked
    in the 1980's and declined or held steady since then. Professor
    Francois Morel of Princeton University, and colleagues,
    recently analyzed specific tuna for mercury, comparing recent
    catches with those from the 1970's. Despite changes in mercury
    emissions over those 30 years, mercury levels in tuna did not
    change between the samples. One conclusion they reached is that
    the mercury in such marine fish is not coming from emission
    sources on land, but from natural submarine sources of mercury.
    Again, this implies there may be a management floor for mercury
    in marine fish, which make up most of the U.S. fish diet.
        Third, how can potential mercury reductions change mercury
    deposition? EPRI recently completed work to assess what might
    ensue in the atmosphere and in U.S. fish if further mercury
    emission reductions are carried out in the United States. The
    approach linked models of atmospheric mercury chemistry and
    physics with Federal data on mercury in fish in the U.S. diet,
    along with a model of costs that would be needed to attain a
    given reduction level. There are currently about 179 tons of
    mercury depositing each year in the United States from all
    sources, global and domestic. Current U.S. utility emissions of
    mercury are about 46 tons per year.
        EPRI examined one proposed management scenario that cut
    these utility emissions from 46 tons to 25 tons per year. The
    analysis showed that this emissions cut of 47 percent resulted
    in an average 3 percent decline in mercury deposition in the
    United States. Some isolated locations making up less than one
    one-hundredth of the U.S. land area experienced drops of up to
    30 percent. The economic model showed that costs to attain
    these lower levels would be between $2 billion and $5 billion
    per year for 12 years. This demonstrated U.S. mercury patterns
    may be relatively insensitive to the effects of this single
    category of sources.
        In addition, most of the fish consumed in the United States
    are ocean fish which would be only slightly impacted by a
    reduction of 24 tons of mercury per year solely in the United
    States, out of 2,300 tons globally. Wild freshwater fish within
    the United States might show a greater reduction in mercury
    content, but they make up a very small part of the U.S. diet,
    compared to ocean or farm-raised fish.
        These deposition changes were translated into how much less
    mercury might enter the U.S. diet via these three categories of
    fish. We found that less than one-tenth of 1 percent fewer
    children would be born at-risk due to their mother's taking in
    mercury at lower levels from fish consumed in the diet.
        So to summarize, a drop of nearly half in utility mercury
    emissions resulted in an average drop of 3 percent in mercury
    depositing to the ground, and a drop of less than one-tenth of
    a percent in the number of children at risk. These recent
    findings are a small part of the massive international research
    effort to understand mercury and its impacts. EPRI and others,
    including U.S. EPA and the Department of Energy, are jointly
    racing to clarify the complex interactions of mercury with
    natural systems, an important part of its cycling, and its
    impacts on human health. With improved understanding, informed
    decisions can be made on the best ways to manage mercury.
        Thank you for this opportunity to deliver these comments to
    the committee.
        Senator Inhofe. Thank you, Dr. Levin.
        Dr. Rice.

         STATEMENT OF DEBORAH C. RICE, TOXICOLOGIST, BUREAU OF
         REMEDIATION AND WASTE MANAGEMENT, MAINE DEPARTMENT OF
                        ENVIRONMENTAL PROTECTION

        Dr. Rice. I would like to thank the committee for this
    opportunity to present information on the adverse health
    consequences of exposure to methyl-mercury in the United
    States.
        I am a neurotoxicologist who has worked on the
    neurotoxicity of methyl-mercury for over two decades and have
    published over 100 papers on the neurotoxicity of environmental
    chemicals. Until 3 months ago, I was a senior toxicologist at
    the Environmental Protection Agency. I am a coauthor of the
    document that reviewed the scientific evidence on the health
    effects of methyl-mercury for EPA. This document included the
    derivation of the acceptable daily intake level for methyl-
    mercury.
        I would like to focus on four points. No. 1, there is
    unequivocal evidence that methyl-mercury harms the developing
    human brain. No. 2, EPA used analyses of three large studies in
    its derivation of an acceptable daily intake, including the
    studies in the Seychelles Islands which found no adverse
    effects. No. 3, 8 percent of women of childbearing age have
    levels of methyl-mercury in their bodies above this acceptable
    level, and studies have documented cardiovascular disease in
    men at low levels of methyl-mercury, suggesting that an
    additional potentially large segment of the population is at
    risk.
        Studies performed around the world have documented harmful
    effects of environmental methyl-mercury exposure on children's
    mental development. Three major studies were analyzed by the
    National Research Council panel in their expert review: In the
    Faroe Islands in the North Atlantic, and the Seychelles Islands
    in the Indian Ocean, and in New Zealand. Two of these major
    studies, as well as six smaller studies, identified impairment
    associated with methyl-mercury exposure. The Seychelles Island
    study is anomalous in finding no effects. Adverse effects
    include decreased IQ and deficits in memory, language
    processing, attention and fine motor coordination.
        The NRC modeled the relationship between the amount of
    methyl-mercury in the mother's body and the performance of the
    child, and calculated the level associated with the doubling of
    the number of children that would perform in the abnormally low
    range. The NRC panel did this for each study separately and for
    all of the three studies combined, including the negative
    Seychelles study.
        EPA used the NRC analyses in deriving its acceptable daily
    intake level of methyl-mercury. EPA performed the relevant
    calculations based on each of the two positive studies, as well
    as the integrative analysis of all three studies. The
    acceptable level is the same whether it is based on the
    integrative analysis of all three studies, or on the Faroe
    Islands study alone.
        The acceptable level would be lower if only the New Zealand
    study were considered. Only if the negative Seychelles study
    alone were used, while ignoring the values calculated for the
    Faroe Islands and New Zealand studies, would the acceptable
    intake level be higher than the current value. EPA believed
    that to do so would be scientifically unsound and would provide
    insufficient protection to Americans.
        Data from a survey representing the U.S. population
    collected over the last 2 years revealed that about 8 percent
    of women of childbearing age had blood concentration of methyl-
    mercury above the level that EPA believes is safe. This
    translates into over 300,000 newborns at risk for adverse
    effects on intelligence and memory, ability to pay attention,
    language skills and other abilities that are required to be
    successful in our highly technological society.
        There is an additional concern regarding the potential for
    harm as a result of environmental methyl-mercury exposure.
    Three studies found a relationship between increased methyl-
    mercury levels and atherosclerosis, heart attacks and death,
    and it is unknown whether there is a level of mercury that will
    not produce harm. It is important to understand that the
    cardiovascular effects associated with methyl-mercury may put
    an additional very large portion of the population at risk.
        In summary, there are four points that I would like the
    committee to keep in mind. First, at least eight studies based
    on populations around the globe found an association between
    methyl-mercury levels and impaired neuropsychological function
    in children. The Seychelles Islands study is anomalous in
    finding no effects. Second, both the NRC and the EPA included
    the Seychelles Islands study in their analysis. The only way
    that the acceptable intake of methyl-mercury could be higher
    would be to ignore the two major positive studies, as well as
    six smaller studies and rely solely on the one study that
    showed no effects.
        Third, there is a substantial percentage of women of
    reproductive age in the United States with levels of methyl-
    mercury in their bodies above what EPA considers safe. As a
    result, over 300,000 newborns each year are exposed to
    potentially harmful levels of methyl-mercury. Fourth, increased
    exposure to methyl-mercury may result in cardiovascular disease
    and even death in men from heart attack, suggesting an
    additional large segment of the population is at risk.
        Additional information has been provided to the committee.
    Thank you for your time and attention.
        Senator Inhofe. Thank you, Dr. Rice.
        Dr. Myers.

    STATEMENT OF GARY MYERS, PROFESSOR OF NEUROLOGY AND PEDIATRICS,
    DEPARTMENT OF NEUROLOGY, UNIVERSITY OF ROCHESTER MEDICAL CENTER

        Dr. Myers. Thank you for the opportunity to present the
    views of our research group on the health effects of methyl-
    mercury exposure. My name is Gary Myers. I am a pediatric
    neurologist and a professor at the University of Rochester in
    New York, and just one member of a large international team
    that has been studying the human health effects of methyl-
    mercury for nearly 30 years. For 20 of those years, our group
    has specifically studied the effects of prenatal methyl-mercury
    exposure.
        In 1971 and 1972, there was an epidemic of methyl-mercury
    poisoning in Iraq. The source of exposure, unlike in Japan, was
    maternal consumption of sea grain coated with a methyl-mercury
    fungicide. We looked at a number of children in that study and
    measured the exposure of the fetus using the maternal hair as
    the biomarker. It is the only biomarker that has been
    correlated with brain levels. We concluded that there was a
    possibility that exposure as low as 10 parts per million in
    maternal hair might be associated with adverse effects on the
    fetus. This value is over 10 times the average in the United
    States and five times the average in Japan, but individuals
    consuming large quantities of fish can easily achieve this
    level.
        The hypothesis of our study in the Seychelles was that
    methyl-mercury from fish consumption might affect child
    development. In fact, we all thought it would. Since millions
    of people around the world consume fish as their primary source
    of protein, we thought it was only reasonable to investigate
    the question directly. We selected the Seychelles because of
    two reasons. First, they eat large amounts of fish. The average
    mother eats 10 times as much as women here in the United
    States.
        Second, the fish in Seychelles has an average mercury
    content of about 0.3 parts per million, which is approximately
    the same as commercial fish here in the United States. The
    Seychelles study is a collaborative study which was begun under
    the auspices of the WHO and has been carried out by a U.S.-led
    team of international researchers from the University of
    Rochester, Cornell University and the Ministries of Health and
    Education in Seychelles. The funding has come from the National
    Institutes of Environmental Health Sciences, with some minor
    funding from the Food and Drug Administration and the
    governments of Seychelles and Sweden.
        The Seychelles was chosen for a number of reasons,
    primarily because there was no overt mercury pollution and many
    of the factors that complicate epidemiological studies of low-
    level exposures were simply not present. There was universal
    free and readily available health care in Seychelles. Prenatal
    care is nearly 100 percent. The birthrate is high and the
    general health of the mothers and children is very good. In
    addition, education is free, universal, and it starts at age
    3\1/2\.
        Before starting the study, we carefully controlled for a
    number of things. To minimize the possibility of bias, a number
    of decisions were made. First, no one in Seychelles, including
    any of the researchers who visit the island, would know the
    level of exposure of any child or mother unless our results
    indicated that children were indeed at risk. Second, because of
    the known problems with developmental delay in certain
    disorders, those children would be excluded from the study.
    Third, the tests administered would include all of the tests
    that have been used in other studies, plus other things that we
    thought might detect subtle changes.
        Fourth, we would do this testing at specific age windows.
    Fifth, we would adjust for multiple confounding factors, things
    that are actually known to affect child development such as
    socioeconomic status, the mother's intelligence, and birth
    weight. And sixth, we established a data analysis plan before
    the data were collected to minimize the possibility that the
    data would just be repeatedly analyzed until the anticipated
    effect was in fact determined.
        We have now carried out five evaluations of the children
    over 9 years. The study has focused on prenatal exposure. The
    exposure of both mothers and children has been in the range of
    concern, from 1 to 27 parts per million. We have done extensive
    testing with over 57 primary endpoints determined so far. The
    study has found three statistical associations with prenatal
    methyl-mercury exposure. One was adverse; one was beneficial;
    and one was indeterminate. These results might be expected to
    occur by chance and do not support the hypothesis that adverse
    developmental effects result from prenatal methyl-mercury
    exposure in the range commonly achieved by consuming large
    amounts of fish.
        The findings from our research have been published in the
    world's leading medical journals, including the Journal of the
    American Medical Association, the Lancet, and a soon-to-be-
    published review in the New England Journal of Medicine. We do
    not believe that there is presently good scientific evidence
    that moderate fish consumption is harmful to the fetus. In the
    words of Dr. Lyketsos, a distinguished researcher from Johns
    Hopkins, who wrote the editorial with our Lancet articles:

              ``On balance, the evidence suggests that methyl-mercury
            exposure from fish consumption during pregnancy of the levels
            seen in most parts of the world does not have measurable
            cognitive or behavioral effects in later childhood. However,
            fish is an important source of protein in many countries and
            large numbers of mothers around the world rely on fish for
            proper nutrition. Good maternal nutrition is essential to the
            baby's health.''

        Thank you.
        Senator Inhofe. Thank you, Dr. Myers.
        We are going to try to adhere to a 5-minute round of
    questioning. Let me just share with you, which I think you
    already know, you folks are looking at the medical effects of
    mercury. We also up here have to consider the economic
    effects--the problems that are out there. Right now on the
    Senate floor, they are debating the energy bill. We have an
    energy crisis in this country, and if cofire should go out, and
    that could happen from either CO2 or mercury, it
    would be a very serious crisis. I think anticipating that this
    will happen, several people have moved off-shore, moved to
    other places. So that is something that is really, I guess you
    would say our major, at least one of my major concerns.
        Now, just for all of the witnesses, you stated that the
    U.S. utility mercury emissions are 46 tons a year. Tell us what
    happens to this mercury. Help us visualize where does it come
    from; where does it go; how much is deposited in the United
    States; how does this compare with the amount that is deposited
    in the United States from global sources.
        Would you like to start, Dr. Rice?
        Dr. Rice. That is really not my area of expertise, so I
    cannot speak to it.
        Senator Inhofe. All right.
        Dr. Myers.
        Dr. Myers. It is not my area of expertise.
        Senator Inhofe. Come on, Dr. Levin.
        Dr. Levin. All right.
        [Laughter.]
        Dr. Levin. Utility mercury of the various sources of
    mercury is probably the best-studied category, partially
    because there are more individual sources than there are of
    many of the other categories. We believe that roughly half on
    average coming out from utilities is made up of the divalent
    form of mercury, which is about a million times or so more
    soluble in water than the elemental form, which is the silvery
    liquid that you probably remember from high school chemistry.
    So of this mercury emitting from all utilities in the United
    States, roughly half of it is more highly water soluble and the
    other half will tend to go into regional and global
    circulation.
        We calculate that about 70 percent or so of the mercury
    emitted from utilities leaves the United States, and the other
    30 percent or so deposits within the United States across the
    country. These are somewhat similar to the numbers that EPA is
    deriving as well. Some of this mercury that deposits to the
    surface will wind up in receiving waters, and a very small
    fraction of it, probably less than 1 percent, will eventually
    be turned into the organic form by bacterial action. It is that
    organic form that has the potential to reach humans through
    accumulation in some fish.
        Again this does not happen in all waterways and with all
    fish species. It tends to happen in waterways that have full
    food webs that go to high-level fish that grow quite large, and
    it is larger, older fish that tend to accumulate more mercury.
        Of the exposure in the community in the United States,
    almost all of it is through intake from fish and the mercury in
    those fish, although the levels taken in can vary from very
    little or almost none, to amounts of concern. There is almost
    no exposure by inhalation. That is a very small part of the
    exposure.
        So our concern is to follow this mercury from its sources
    through to where it winds up in fish and eventually may be
    consumed by humans. That is the trick, scientifically.
        Senator Inhofe. Thank you, Dr. Levin.
        Dr. Rice, the American Heart Association and the World
    Health Organization recommend that fish should be a part of
    everyone's diet, concluding that the benefits of eating fish
    outweigh the risks of adverse effects, which as you state in
    your testimony are potential risks. Since eating fish offers
    substantial health benefits, shouldn't the EPA's referenced
    dose be revised to take this into account, or does it?
        Dr. Rice. Well, I agree totally, and I have to say that I
    am no longer with EPA so I am not speaking as a representative
    of the agency. I need to make that clear. So some of these
    opinions will be those of the agency when I left, and some will
    be mine.
        But the scientific community at large and the EPA and me
    personally recognize that fish is a good source of protein. It
    also confers cardio-protective effects. There are also omega-
    three fatty acids in fish that are essential when the fetus is
    building its brain. There is new evidence that eating fish also
    may be beneficial to the mental development or the mental
    function of the elderly. I suspect that it is probably
    important for all of us.
        So the dichotomy is not eat fish/don't eat fish. The
    important thing to be able to do is to come out with some
    recommendations to the community that allow people to eat fish,
    but not to eat fish that has increased levels of methyl-
    mercury. So EPA thinks that, I was part of that EPA panel, so
    when I was part of that EPA panel we firmly believe that the
    RFD should not be any higher, and in the light of some evidence
    that we were not able to analyze at the time, might even should
    be lower than it is presently.
        So it is not a question of increasing the reference dose.
    It is a question of making sure that the American public can
    eat fish that does not have undue levels of methyl-mercury in
    them.
        Senator Inhofe. Thank you very much.
        Dr. Myers, in selecting the Seychelles as a location for
    your research, what other locations did you consider other than
    the Seychelles Islands?
        Dr. Myers. We started studies on the coast of South America
    and looked also at the Maldive Islands as another possibility.
        Senator Inhofe. Yes. I kind of wanted to get to the Faroe
    Islands. Did you consider them for your research?
        Dr. Myers. We did not consider the Faroes in our research.
        Senator Inhofe. It is my understanding that, and for those
    of us who are not scientists here, that some of the problems,
    let's take the Faroe Islands and see if I have this right, that
    there is an inordinate amount of whale meat that is consumed
    there and there are PCBs in there. I do not know whether you
    can distinguish between the harm of one or the other, but is
    this a factor that should be considered?
        It is my understanding, and I won't say this right, but
    there are different levels of mercury that are found. One is
    from the primary fish, and the other is from whales that eat
    other fish, so it has a multiplying effect. Is this taken into
    consideration?
        Dr. Rice. The Faroe Islands study and the Seychelles
    Islands together have been reviewed by at least two very
    distinguished peer-review panels. That issue, the issue of the
    pattern of intake of methyl-mercury and potential co-exposure
    for PCBs has been discussed extensively by the scientific
    community.
        The Faroe Islands' population does eat whale meat. They may
    eat a large whale dinner occasionally. They also tend to dry
    the whale meat, and so they snack on it in addition to eating a
    so-called bolus dose, what we call a bolus dose. So they have a
    low level of methyl-mercury intake which may be occasionally
    punctuated with a higher intake level. The source of methyl-
    mercury does not matter, whether it is through fish or through
    whale. So the fact that it is whale meat per se is not really
    relevant.
        None of the panels, including the National Research Council
    panel, could come to any kind of conclusion about the
    importance of the pattern of intake, because the data just are
    not available. There just are not scientific data that speak
    directly to that. But what the Faroe Islands investigators have
    done because this was raised as a concern and because they have
    hair, and they had hair from their population that was stored,
    they were able to go back and do segmental analysis, so that
    you cut the hair up into tiny little pieces and look at mercury
    levels across the length of the hair.
        What they did was they eliminated the mothers that had the
    most variable hair levels that might suggest that there was
    this bolus exposure of these particular women and these
    particular fetuses. What they found was that the effect was
    actually stronger when they eliminated these women, which makes
    a certain amount of sense because you are decreasing
    variability when you do that.
        Senator Inhofe. Thank you, Dr. Rice.
        Senator Jeffords.
        Senator Jeffords. Thank you all for your testimony on this
    very important and timely topic.
        Some of you have seen this morning's New York Times full-
    page article on mercury and its health effects. This helps to
    set a context for our discussion.
        Dr. Rice, what exactly is a reference dose level and what
    does it mean in terms of the so-called safe levels of fish
    consumption? Does EPA reference dose level include a built-in
    tenfold safety threshold?
        Dr. Rice. The reference dose is designed to be a daily
    intake level that a person could consume over the course of
    their lifetime without deleterious effects. So it is designed
    to be the amount of mercury you could eat every day in your
    life and not harm yourself.
        Now, when EPA did its calculation, it is important to
    understand that when the National Academy of Sciences modeled a
    number of endpoints for each of the studies, and those were the
    Faroe Islands study, the New Zealand Study, both of which found
    effects, as well as the Seychelles study which did not, they
    identified not a no-effect level. They identified a very
    specific effect level. That effect level is associated with a
    doubling of the number of children that would perform in the
    abnormal range, in other words, the lowest 5 percent of the
    population. So this is in no way a no-effect level.
        To that, the EPA applied a tenfold so-called uncertainty
    factor. The point of that was to take into account things that
    we did not know, data that we did not have, as well as the
    pharmacodynamic and the pharmacokinetic variability. Now, there
    were actually data that was again modeled by the NAS and
    reviewed by the NAS, that says that the pharmacokinetic
    variability, in other words the woman's ability to get rid of
    methyl-mercury from her body, differs by a factor of three. So
    that already takes up half of the uncertainty factor.
        But in addition to that, it is important to understand that
    when the Faroe Islands folks analyzed their data, they
    eliminated mothers with mercury levels above 10 ppm in their
    hair, which was really right about at the effect level that the
    NAS identified. The effects were just about as strong even
    below 10 ppms. So again, that is very strong evidence that
    there is not a factor of 10 safety.
        In addition to that, when the NAS modeled their data, it
    turned out that both of the New Zealand study and the Faroe
    Islands study not only was there no evidence that there was a
    threshold, in other words a level below which there were no
    effects, but in fact the curve was actually steeper at the
    lower levels. The NAS used a straight line when they modeled
    the data because they were uncomfortable about using curves
    that were steeper at the lower end than they were at the higher
    end, but subsequent to that there have been studies come out
    with regard to lead exposure, for example. There are now
    several studies where that has also been found for lead
    exposure.
        So this may in fact be a very real effect. So not only is
    there not a safety factor of 10. There might be virtually no
    safety factor at all.
        In addition to that, something that EPA recognized at the
    time, but we were not able to quantitate because we did not
    have the data, but it has now been quantitated, we assumed that
    the relationship between the mother's blood level of methyl-
    mercury and the fetus' blood level of methyl-mercury were the
    same, because of course we have the body burden; we have cord
    blood in the fetus, we have to get back to intake by the
    mother. We know now that in fact the ratio is more like 1.7,
    and for some mothers it is as much as over 3.
        So if we were to recalculate the reference dose just based
    on this new information, it would decrease from 0.1 to 0.06.
        Senator Jeffords. Dr. Rice and Dr. Myers, would you
    recommend that Members of Congress and regulatory agencies base
    their decisions on whether and how much to reduce human-made
    mercury emissions on the findings from any one study?
        Dr. Myers. Our group has been involved in the science of
    studying whether you could find effects at low levels, and we
    have not been involved in policy. There is a general scientific
    principle, I think it is important to look at multiple
    different studies. However, these studies are complicated and
    one has to look at what kind of studies you are dealing with.
    Some are simply descriptive. They take a group of people and
    describe something. It is a basic epidemiological principle
    that you cannot assign causation from a descriptive study.
        So one has to look at the studies that are larger and
    follow children over time, and control for a lot of confounding
    factors which complicate these type of studies very much
    actually. The Seychelles study in fact is not a negative study,
    as has been stated. We did, in fact, find associations with
    things that are known to affect child development, such as
    socioeconomic status, maternal intelligence, the home
    environment and other things. What we did not find was an
    adverse association with prenatal methyl-mercury exposure in
    the Seychelles.
        Senator Jeffords. Dr. Rice.
        Dr. Rice. I agree with Dr. Myers. These studies are very
    complex. I think that that is even more reason not to rely on
    one study while eliminating other studies for consideration.
        Again, these studies have been peer-reviewed numerous
    times. The Seychelles Islands study and the Faroe Islands study
    have been reviewed now by several panels. They are both thought
    to be very high quality, very well-designed and well-executed
    studies.
        The NAS, as well as the previous panel, talked at great
    length about what might account for the differences between
    these studies. We really do not know what accounts for the
    differences between these studies. The NAS modeled three
    studies. The New Zealand study was also a positive study.
        The National Academy of Sciences and the EPA agreed with
    them that it was not scientifically justifiable for protection
    of the health of the American public to rely on the negative
    study and exclude the two positive studies. I said at least a
    couple of times in my testimony that what the NAS did to try to
    address that was to do an integrative analysis that included
    all three studies, including the Seychelles Islands study, and
    modeled it statistically.
        When EPA then took those analyses and derived, what we did
    was we derived a series of reference doses, kind of sample
    reference doses, that were based on a number of endpoints from
    both the New Zealand study and the Faroe study, as well as the
    integrative analysis of all three studies. The integrative
    analysis of all three studies also yields a reference dose of
    0.1. So that made me personally very comfortable that we were
    doing the right thing scientifically in our derivation of the
    reference dose.
        Senator Inhofe. These are supposed to be 5-minute rounds
    and it has been 8 minutes, so we will recognize Senator Allard.
        Senator Allard. Dr. Rice and Dr. Myers, you have in your
    comments talked about methyl-mercury as being the toxic
    compound as far as human health is concerned. Are there other
    mercurial compounds that are toxic to humans?
        Dr. Rice. Yes. All forms of mercury are toxic to humans.
        Senator Allard. Including the elemental form?
        Dr. Rice. Yes.
        Senator Allard. OK.
        Dr. Rice. But in terms of environmental exposure, it is
    really the methyl-mercury form that we are worried about
    because that is the form that gets into the food chain and is
    concentrated and accumulated up the food chain. That is what
    people actually end up being exposed to.
        Senator Allard. OK. Thanks for clarifying that. I
    appreciate that. So this gets into the environment and
    consequently in the fish or food chain or whatever. Is the
    starting point always bacteria operating on the elemental form
    of mercury? Or is it these various compounds that bacteria
    operate on and then end up being assimilated into the food
    chain? How does that happen?
        Dr. Rice. In most circumstances, it is the inorganic form,
    not the elemental mercury, but the inorganic form that is
    available to be taken up by various microorganisms.
        Senator Allard. How do we get to that organic form, the
    methyl-mercury? How do we get there?
        Dr. Rice. The microorganisms actually put a methyl group on
    as part of their metabolic processes.
        Senator Allard. Do they get that from elementary mercury?
    Is that the origin, or is it various compounds of mercury?
        Dr. Rice. Yes, it is just straight mercury. Now, in the
    Japanese outbreak, it was actually methyl-mercury that was put
    into the water, but that is a relatively unusual situation.
        Senator Allard. I see. OK, so my understanding, Dr. Levin,
    is that a lot of the mercury that is introduced into the
    environment of this country does not originate within the
    borders of this country. Is that correct? The suggestion is
    that a lot of the sources of mercury that come across that we
    may pick up in the soil is actually carried over by wind and
    what not from the Asian countries. Is that correct?
        Dr. Levin. That is correct, Senator, as far as the modeling
    shows, and that is consistent with work that EPRI has done, EPA
    and others have also done in the modeling.
        Senator Allard. Is this the elemental mercury that is being
    brought over?
        Dr. Levin. It is elemental, or the elemental form. It is
    also the inorganic form or the form that can be combined into
    salts.
        Senator Allard. Now, the inorganic form is not processed
    into the food chain? Did I understand that correctly?
        Dr. Levin. It is the inorganic form that is processed into
    the food chain.
        Senator Allard. Yes, it is the organic form.
        Dr. Levin. The two forms that are emitted from combustion
    sources are the elemental form, the chemicals found on the
    periodic chart.
        Senator Allard. Right.
        Dr. Levin. And the inorganic form, which combines with, for
    example, chlorine, to form the pure chloride, or is the form
    also found in minerals. Those two forms that wind up in the
    proper aquatic environments, it is the inorganic form that may
    be methylated and turned into the organic form.
        Senator Allard. Right.
        Dr. Levin. But it has to go from elemental to inorganic
    before the methylation can occur.
        Senator Allard. But my question is, is that the type of
    mercury that is being brought in from Asia, what form of
    mercury is that?
        Dr. Levin. Because of its long-range transport, it is
    primarily the elemental form, but the atmospheric chemistry of
    mercury changes that progressively into the inorganic form,
    which is the form that readily deploys.
        Senator Allard. Now, can the inorganic form be transferred
    into methyl-mercury?
        Dr. Levin. Yes, sir. That is the form.
        Senator Allard. So all those type of compounds get acted on
    by bacteria and then that is how that gets into the food chain.
        Dr. Rice. The elemental form and the inorganic form are
    converted back and forth.
        Senator Allard. I see.
        Dr. Rice. So it does not make any difference whether it
    reaches the North American shores as elemental mercury or
    inorganic mercury. Once it is deposited into the soil or the
    river, it is going to become inorganic mercury that then
    becomes available to be able to be turned into methyl-mercury.
        Senator Allard. OK, thank you.
        Now, here is the question, and I would like to have all of
    you respond to this. In your opinion, would a decrease in U.S.
    anthropogenic mercury emissions have an effect on global
    mercury levels? And part of the rest of the question is,
    apparently there is a high percentage of mercury present in the
    United States from outside our borders, so what effects can we
    expect from a decrease in our emissions? We have a couple of
    questions there and I would like to have all of you respond to
    those if you would.
        Dr. Rice. There is no question that there is a global
    cycling of mercury. A lot of the mercury in the United States
    comes in from someplace else, comes in from the West, but some
    of it may have in fact originated in the United States
    originally. This stuff really does circle the globe. So just
    because it is coming in from the West does not mean it wasn't
    ours to start with.
        Senator Allard. We do not know how much starts here.
        Dr. Rice. No, we do not, and I am not a modeler so I really
    cannot speak to that. But what I do know is that there is local
    deposition. In other words, the mercury that is released from
    power plants in the Midwest ends up downwind. I just moved to
    Maine, and Maine is the so-called tailpipe for that local
    deposition, for that local emission. There is a percentage of
    it, and Dr. Levin can tell you what the percentage is better
    than I can, that is locally deposited. I think it is something
    like 30 percent.
        Getting rid of those local sources would certainly at least
    help the Northeastern United States. Originally, the modeling,
    it was thought that this would take a long, long time. There
    are newer data now where small studies have actually been done
    that suggest that it might not be as grim as we originally
    thought; that these local changes can take place in a
    relatively shorter time, over the course of several years,
    rather than decades and decades as we originally may have
    feared.
        Senator Allard. Dr. Myers, do you have a comment on that?
        Dr. Myers. It is outside of my area of expertise.
        Senator Allard. Dr. Levin.
        Dr. Levin.  Dr. Rice is primarily correct on that. The
    deposition within the United States makes up about 30 percent
    of U.S. emissions. The rest of the emission go globally. Our
    modeling considered the fate of U.S. emissions and accounted
    for the amount that basically circles the globe and comes down
    after one trip around the world.
        It is also correct that there is local deposition that in
    some cases may be significant near particular groupings of
    sources. I indicated that in my testimony, that although the
    average change in deposition for the scenario was 3 percent,
    there were some small areas where it was as much as 10 times
    that on a percentage basis.
        So it calls for more detailed studies and particularly more
    looking at the science of tracking mercury found in fish back
    to its sources scientifically, that is, figuring out where it
    came from.
        Senator Allard. Thank you, Mr. Chairman. I believe my time
    has expired.
        Senator Inhofe. Yes, thank you.
        Senator Carper.
        Senator Carper. Thank you, Mr. Chairman.
        To our witnesses, again thank you for joining us. Thank you
    for your patience in bearing with us.
        Dr. Rice, did I understand you to say you have concluded
    two decades of work at EPA?
        Dr. Rice. Well actually most of it was not at EPA. I was at
    Health Canada for 22 years. I am American, but I graduated from
    the University of Rochester, got my Ph.D. from the University
    of Rochester so I have known Dr. Myers for many years. Then I
    went up there to work at Health Canada.
        Senator Carper. I see. Thank you for your service at EPA,
    and thank you all for real interesting testimony today.
        Sometimes these are fairly technical issues. What is
    helpful for me as I listen to the comments of each of your
    testimonies and your responses to our questions is to look for
    threads of consensus; not to focus so much on where you
    disagree, but to find some areas where you agree. I would just
    ask each of you to take a minute or two and just to talk about
    some of the areas where you think you agree, and which might be
    helpful to us as we wrestle with whether to craft legislation,
    enact legislation along the lines that Senator Jeffords has
    introduced, I have introduced, or the President has proposed.
        Can you help me with that? Dr. Levin, why don't you go
    first.
        Dr. Levin. Thank you, Senator. We agree that mercury is a
    highly toxic compound. Its presence in the U.S. diet may in
    some instances cause concerns for development of children
    neurologically. We agree that there may be other effects that
    have to be looked for in terms of the health effects.
        We also agree that the science of mercury is still
    emerging; that the linkage between health effects in particular
    areas, or for that matter in entire regions of the United
    States, and the sources of mercury is a critical question that
    would shape a wise course toward management decisionmaking. The
    work that I have been describing today is a step in doing that.
    The work that has been described by the other two witnesses
    today on health effects is a critical part of that linkage.
        Bringing this source-receptor issue together with the
    health effects on a specific geographic basis and among
    specific populations within the United States is a key part in
    answering the management questions.
        Senator Carper. Thank you.
        Dr. Myers, would you take a shot at my question please?
        Dr. Myers. I think we all agree that mercury is poisonous,
    every form. In high enough amounts, it is not only damaging to
    human health, but fatal generally. We all agree that it is
    worthwhile cleaning up the environment, I think. The question
    resolves at what level and at what cost. I think we all agree
    that these studies are extremely difficult to carry out and
    they are equally difficult to interpret because there are so
    many details to them. So it is so easy to end up with a bias
    either knowingly or unknowingly, generally I think unknowingly,
    that the interpretation of the details becomes incredibly
    important in these studies.
        Senator Carper. Thank you.
        Dr. Rice.
        Dr. Rice. I agree that we all know that methyl-mercury is
    toxic at high levels. There is absolutely no question about
    that. I agree with Dr. Myers that it is incredibly difficult to
    interpret these studies very often. They are very complex
    studies. There are a lot of variables, many of which we do not
    know. Epidemiology is an extremely blunt instrument. So that is
    why I think that it is important to look at the weight of
    evidence. There are a number of studies in humans that have
    documented effects of methyl-mercury at relatively low body
    burdens. In addition to that, there is a huge animal literature
    documenting effects and looking at the mechanisms of effects.
        We do not know why one study may be positive, whereas
    another may be negative. So we really have to go with the
    evidence as a whole.
        Senator Carper. And maybe cite your most serious area of
    disagreement among you as panelists.
        Dr. Levin. I would say disagreement probably rests in the
    question of the direction of research overall on the mercury
    issue, and how far that should continue.
        Senator Carper. Dr. Myers.
        Dr. Myers. I think the most serious area of disagreement is
    in the interpretation of the studies. We think that the Faroe
    Islands research is outstanding research. They have done a
    wonderful job. They have a great design. We are just not sure
    that they have been able to tease out from the mixture of
    chemicals present in whales a methyl-mercury component to it.
    That requires a lot of faith in their statistics and the
    details of the studies.
        In the case of the New Zealand study, most people
    discounted the New Zealand study for many years. It was only
    when it was reanalyzed in the late 1990's that people began to
    start thinking of it in other terms. So I think our biggest
    disagreement is in the interpretation of it.
        In addition, I think the weight of hundreds of small poorly
    done studies in difficult places such as the Amazon would never
    outweigh a really good study done looking at fish consumption.
        Senator Carper. Dr. Rice.
        Dr. Rice. I guess everything that Gary Myers just said is
    my biggest point of disagreement. All of the smaller studies
    are not poorly done. Some of them are well done. The Faroe
    Islands study and the Seychelles study have been extensively
    reviewed. They are both considered to be very, very good
    studies.
        The National Academy of Sciences looked at the issue of PCB
    co-exposure very, very carefully and asked the investigators to
    go back and do a number of additional analyses. Their
    conclusion was that the effects seem to be independent of each
    other. These are both neurotoxicants. Although they both had
    effects in the study, the NAS conclusion was that they were
    independent.
        Again, I think that we have go with a preponderance of
    evidence and not on just one study, no matter how well it has
    been done.
        Senator Carper. Mr. Chairman, I think this panel has been
    especially helpful to me. We thank you very, very much for your
    contributions today. Thank you.
        Senator Inhofe. Thank you, Senator Carper.
        Senator Clinton.
        Senator Clinton. Thank you, Mr. Chairman. I, too, want to
    thank the panel and welcome Dr. Myers from the University of
    Rochester, and Dr. Rice, your connection with Rochester, we
    will claim that as well.
        I want to pick up where Dr. Rice just concluded. We have
    set up a system of evidence in our legal system that looks at
    the preponderance of evidence; that looks at a reasonable
    person standard. I share Dr. Rice's concern that we are not
    adequately responding to the evidence we already have, which I
    think the preponderance of it, certainly based on the review by
    the National Academy of Sciences, suggests that we have a
    problem with the transmission mostly in utero by mother to
    child that leads to neurological problems that in turn lead to
    poor school performance.
        The 2000 report of the National Academy of Sciences found,
    I believe, that about 60,000 children might be born in the
    United States each year with this level of exposure that could
    affect school performance, but in your testimony you claim that
    more recent results from the CDC's National Health and
    Nutrition Examination Survey translate into over 300,000
    newborns per year. Is that correct?
        Dr. Rice. Yes. When the NAS did their analysis, the NHANES
    data was not available. The NHANES just started taking mercury
    blood and hair levels a couple of years ago, so those data have
    really become available since the NAS. They state that their
    60,000 children was an estimate. It is actually about 320,000
    children. Based on actual data that is representative of the
    U.S. population, it is above the EPA's reference dose.
        Senator Clinton. To me, this is truly alarming, that we
    have actual blood, hair sample, other kinds of physical
    examination which demonstrates that hundreds of thousands of
    our children are born each year potentially at risk for adverse
    affects on intelligence, memory, ability to pay attention,
    ability to use language and other skills.
        Mr. Chairman, we are facing an increasing number of
    children in our school systems with learning disabilities.
    There are not any easy answers as to why the numbers of
    children with such learning disabilities has increased. Senator
    Jeffords has been a champion of making sure that all children
    are given an adequate education. In New York alone, we have
    260,000 learning-disabled children. That is 50 percent of our
    special ed population. We spend $43 billion each year--$43
    billion--on special ed programs for individuals with
    developmental disabilities between three and twenty-one.
        Of course, not all special ed needs are the direct result
    of methyl-mercury exposure, but if it is demonstrably shown as
    we now have with evidence from the CDC's annual survey that we
    have levels of methyl-mercury in our children's bodies that is
    above what the EPA has determined to be healthy, and in fact
    some of us think the EPA standard is too low, but nevertheless
    if it meets that standard, then I would argue we have got to
    figure out how to address this environmental health challenge
    in a very short order.
        I have been working with a number of colleagues to try to
    address the better data collection and environmental health
    tracking that they need in the Individuals With Disabilities
    Act, and I think similarly on the scientific side with respect
    to better research and better analysis. But it is troubling to
    me that we are looking at a problem where the preponderance of
    the evidence I think is clear, where we know that there is a
    transmission, whether it is 60,000, 150,000, 300,000-plus
    children, and it needs some more effective response.
        I wanted to ask you, Dr. Rice, now that you are in Maine,
    from the State perspective, how closely do you work with the
    State health department on environmental health issues? Do you
    exchange information with the State health department and even
    with the State education department about some of the work that
    you are doing?
        Dr. Rice. I actually knew the State toxicologist for Maine
    quite well before I went up there, so I do interact with the
    health department. The methyl-mercury issue is very important
    to Maine. Maine has a very good program for trying to get rid
    of methyl-mercury from dental amalgams, from thermometers, from
    the kinds of things that can be controlled; to not put mercury
    in landfills because Maine understands that we are at the end
    of the pipeline for methyl-mercury deposition. Maine has a
    terrible problem with fish advisories. There are a lot of
    places where fish cannot be eaten in Maine because of the
    deposition of methyl-mercury.
        So I do work closely with the folks over there, and in fact
    my way here was paid by the air office, the Maine air office
    because the State of Maine is so very concerned about this
    issue. Maine is rural and it is poor, and it cannot really
    absorb the consequences of these kinds of additional exposures
    on the health of the people of Maine.
        Senator Clinton. Similarly, new science is demonstrating
    that we need lower standards for lead, based on what we are now
    determining. A lot of that groundbreaking work was done at the
    University of Rochester about lead exposures and the impacts of
    lead exposure. We can take each of these chemicals or compounds
    piece by piece, but I think that certainly when it comes to
    mercury and lead and their impacts on children's development,
    it is not something I feel comfortable studying and waiting too
    much longer on, particularly because there are so many indirect
    costs. I know that Dr. Levin's work looked at some of the risks
    and cost-benefits, but people do not seem to factor in this
    special education population that has been growing.
        Dr. Rice. If I may make a comment, I think your analogy is
    an apt one, and I think it is a very informative one. In 1985,
    there was a report to Congress on the cost-benefits of lead, of
    keeping lead out of gasoline, in fact. The benefits based on
    not only special education and things like lower birth weight
    with respect to lead, but also just the economic consequences
    of lowering the IQ of workers amounted to billions and billions
    of dollars a year in 1985 dollars or 1994 dollars. So as this
    effort goes forward in terms of figuring out how much it is
    going to cost to reduce mercury emissions, this other side of
    the equation, how much it is going to cost not to, needs to be
    kept very, very well in mind.
        Senator Clinton. Thank you, Dr. Rice.
        Senator Inhofe. Thank you, Senator Clinton.
        I thank the panel very much for their testimony.
        Senator Jeffords. I had a couple more questions.
        Senator Inhofe. Well, all right. It has to end at 12
    o'clock. Go ahead.
        Senator Jeffords. Dr. Levin, before setting a mercury max
    standard, would you agree that it makes sense for EPA to
    conduct a full modeling analysis of all available technology
    options and their emissions reduction potential, including the
    most stringent options?
        Dr. Levin. Yes, Senator. I think it is important for EPA to
    carry out a parallel study as EPRI has done, and to make that
    study public, as we have as well. I am not aware yet that they
    have actually done any modeling of a max standard since there
    has been no official proposal of one yet.
        Senator Jeffords. Dr. Myers, I believe your testimony is
    that the fish consumed with an average mercury content of 0.3
    parts per million has about the same mercury concentration as
    commercial fish in the United States. What are the
    concentration in non-commercial fish?
        Dr. Myers. Are you talking about the United States or the
    Seychelles?
        Senator Jeffords. In the United States.
        Dr. Myers. Well, all fish has some mercury in it. Most of
    the commercial fish in the United States, I understand, has
    less than \1/2\ part per million, but some of the fish, I am
    not sure what the non-commercial ones are, but it can go up to
    over two or three parts per million in some freshwater fish.
        Senator Jeffords. Dr. Rice and Dr. Myers, can you
    characterize the body burden of the pollutants like mercury in
    American children compared to the levels found in the
    Seychelles children?
        Dr. Myers. The average hair level in the mothers in
    Seychelles is 6.9 in the group we were studying. The average in
    the United States is less than one part per million. The
    average in Japan is somewhere around two parts per million.
        Senator Jeffords. Dr. Rice, any comment?
        Dr. Rice. No. That is correct, but I think it is important
    to understand that the NHANES data did identify some women, a
    very small percentage of women with higher hair mercury levels.
    I think it is important also to understand that the NHANES data
    are designed to be representative of the U.S. population as a
    whole, so that women who may eat more fish and may be at more
    risk for increased body burdens of methyl-mercury, such as
    immigrant populations or populations of people who are
    subsistence anglers and who eat inland fish. This is not
    captured. These populations are not captured by the NHANES data
    and I think that this needs to be kept in mind.
        Senator Jeffords. I have some further questions I would
    like to submit.
        Senator Inhofe. That would be perfectly appropriate. I
    appreciate it very much, and I appreciate the panel coming and
    also your patience from the long first session.
        We are now adjourned.
        [Whereupon, at 12 o'clock p.m. the committee was adjourned,
    to reconvene at the call of the chair.]
        [Additional statements submitted for the record follow:]
       Statement of Hon. Jon Cornyn, U.S. Senator from the State of Texas
        Mr. Chairman, I commend you for holding this important hearing
    examining what is known about the science of climate change, mercury
    and the potential health effects of mercury emissions from power
    plants.
        Given the timing of the energy debate on the Floor and this
    Committee's ongoing consideration of the Clear Skies Act, this is a
    very timely and important topic and I commend the Chairman for setting
    time aside to focus on the issue. I realize our focus today in regards
    to climate change is on the science, principally on temperature change.
    Two very different trains of thought are about to be presented to us
    today and I think this is positive and encourages a good, healthy
    debate. The question that this panel has to wrestle with is moving
    ahead with a greenhouse gas policy that may or may not be based on
    sound science. I am concerned about the costs in moving forward when
    there is a large body of science out there that says there isn't a
    problem.
        To shift our focus just a bit, an issue of particular concern to me
    is the available technology to control greenhouse gas emissions,
    specifically CO2. I am fairly certain that some of my
    colleagues agree with the line of thought about to be outlined by Dr.
    Mann, and this could very well lead this committee to a debate imposing
    mandatory controls on CO2. If this turns out to be the case
    it is imperative that this Committee determine whether or not the
    technology is currently available to accomplish CO2
    reductions that are effective enough to solve the ``problems'' thought
    to be faced. I realize this is a topic for another hearing, but one
    that causes me concern.
        In regards to mercury, in the 1990 amendments to the Clean Air Act,
    Congress specifically requested that EPA conduct an analysis of the
    health effects of mercury emissions from power plants and report back.
    EPA did conduct that study in 1997 and concluded that there was a
    ``plausible link'' between mercury emission and potential health
    effects, but was unable to quantify the link.
        Six years have passed since EPA's 1997 study. Unfortunately, we
    still have not received any clarification from the EPA as to the
    magnitude of the health risks posed by power plant emissions, even
    though we are currently on the verge of spending billions of dollars to
    reduce those emissions.
        I suspect that one of the reasons for this lack of information is
    that we are dealing with a global problem. Many people today may find
    it surprising to learn that most of the mercury that is deposited in
    the United States originates from outside our borders. In fact, for
    most of the country, over 60-80 percent of the mercury deposited in the
    United States comes from emission sources located in another country.
    Additionally, natural sources of mercury, such as forest fires and
    vegetation burning, account for over half of the world's mercury
    emissions.
        What this means is that we have control over only a very small
    portion of total mercury emissions. Of the 5500 tons of mercury emitted
    globally, the U.S. accounts for only about 155 tons, or 3 percent of
    global emissions. U.S. power plant emissions which are estimated to be
    48 tons per year, represent less than 1 percent of total global
    emissions. Given how small this fraction is, it is both reasonable and
    prudent to ask what impact controls on power plants will have on actual
    public health.
        While EPA has unfortunately not provided us with any data on that
    question as of yet, Leonard Levin from the Electric Power Industry has.
    According to his very detailed analysis, control programs to reduce
    mercury emissions from power plants are likely to have less than a 1-
    percent impact on public exposure in this country. In fact, he
    estimates an impact of less than 0.3 percent. I do not know if this
    number is correct, but I think his very detailed analysis deserves
    comment from EPA, especially given that this was exactly the kind of
    information Congress sought in 1990 when it amended the Act.
        I look forward to hearing Dr. Levin's testimony, as well as Dr.
    Rice's and Dr. Myers'. Your collective input is critical to this
    committee as we continue to debate the Clear Skies initiative.
        I yield back the balance of my time.
                                     ______

           Statement of Dr. Willie Soon, Harvard-Smithsonian Center
                                for Astrophysics

        Distinguished Senators, panelists, and audience: My name is Willie
    Soon. I am an astrophysicist with the Harvard-Smithsonian Center for
    Astrophysics in Cambridge, Massachusetts. My training is in atmospheric
    and space physics and my sustained research interests for the past 10
    years include changes in the Sun and their possible impact on climate.
        This very rich area of scientific research, though still far from
    having definitive answers, has seen exciting and important progress
    from our increasing technical ability to measure, quantify, and
    interpret the changes in the Sun which could be linked to changes of
    the Earth's climate.
        Today I focus on my latest research conclusions regarding climate
    change over roughly the last 1000 years, especially the geographical
    pattern of those changes. My scientific study is only possible because
    of the careful research produced by nearly one thousand scientists
    around the world. Their expertise covers a very wide range, including
    physical, chemical, biological, and geological sciences.
        Together with several colleagues whose names are listed in the two
    scientific papers that I am submitting today for the record of this
    testimony, we have synthesized the results from several hundred studies
    of proxy records of climate, including much new work that has appeared
    in the scientific literature in the last 5 to 10 years.
        Climate proxies are indirect climate sensors based on information
    from tree rings, ice and seafloor sediment cores, corals, glaciers and
    other natural evidence. They also include important cultural and
    documentary records.
        It is important to recognize that these climate proxies are not
    temperature readings, but some proxies may be calibrated to give
    temperature changes. One example is the measurement of the flow of heat
    in boreholes drilled through rocks or ice, yielding century-scale
    temperature changes over several millennia. On the other hand, some
    proxies are sensitive to local rainfall as well as temperature, as in
    the case of annual tree growth in the southwest United States. Any
    given proxy may respond to temperature differently from other proxies,
    depending on, for instance, the type of proxy, location, or season.
        For all those reasons, it remains a big challenge to produce an
    accurate global temperature record over the past 1000 years from the
    diverse set of climate proxies.
        But within the limits and lessons learned from our research papers,
    we can offer three conclusions:
        First, local and regional, rather than ``global'', changes are the
    most relevant and practical measure of climate change and impact. This
    is because truly global averages rarely are available from the distant
    past, before modern satellite measurements, and because such averages
    can hide the significant changes that can occur over large parts of the
    Earth.
        Second, on a location by location basis, there was a widespread
    Medieval Warm Period between approximately 800 and 1300 A.D. This
    Medieval Warm Period was followed by a widespread colder period, called
    the Little Ice Age, that lasted from approximately 1300 to 1900 A.D.
        Third, there is no convincing evidence from each of the individual
    climate proxies to suggest that higher temperatures occurred in the
    20th century than in the Medieval Warm Period. Nor is there any
    convincing evidence to suggest that either the rate of increase or the
    duration of warming during the 20th century were greater than in the
    Medieval Warm Period.
        The fact that local and regional climate has been varying with
    significant swings in amplitude over many locations provides important
    challenges for computer simulation of climate. The full models that
    explore the Earth region by region can test for the natural patterns of
    change over the last 1,000 years through the use of the climate proxies
    we just discussed. In that way, the effects of human-caused climate
    change can be weighed against observed natural variability in the
    climate system. Having computer simulations reproduce past climate,
    which has been influenced predominantly by natural factors, is key to
    making an accurate forecast that includes all potential human-made
    warming and cooling effects.
        Further research could yield a deeper, quantitative improvement to
    our knowledge of local and regional climate variability during the past
    1000 years. As we could be inspired by Mr. Thomas Jefferson who
    remarked:

              ``It is a common opinion that the climates of the several
            states of our union have undergone a sensible change since the
            dates of their first settlements; that the degrees of both cold
            & heat are moderated. The same opinion prevails as to Europe;
            if facts gleaned from history give reasons to believe that,
            since the times of Augustus Caesar, the climate of Italy, for
            example, has changed regularly at the rate of 1 [degree] of
            Fahrenheit's thermometer for every century. May we not hope
            that the methods invented in latter times for measuring with
            accuracy the degrees of heat and cold, and the observations
            which have been & will be made and preserved, will at length
            ascertain this curious fact in physical history?''--Marginal
            notes from Thomas Jefferson's Monticello Weather Diary (January
            1, 1810 to December 31, 1816).

        I strongly believe that the time for research in paleoclimatology
    to fulfill this important role is now.

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       Response by Dr. Willie Soon to Additional Questions from Senator
                                    Jeffords

        Question 1. In testimony, you said that you did not know whether
    you submitted something for publication to Capitalism magazine. Here is
    the title and web address: ``Global Warming Speculation vs. Science:
    Just Ask the Experts'' by Sallie Baliunas & Willie Soon (Capitalism
    Magazine--August 22, 2002) http://capmag.com/article.asp?ID=1816. Did
    you submit or approve submission of this article for publication?
        Response. With the benefit of your reminder, I hereby confirm that
    the above mentioned article in Capitalism Magazine was taken from the
    original article ``Just Ask the Experts'' by Baliunas and Soon
    originally published by the TechCentralStation.com at the link: http://
    www.techcentralstation.com/072302B.html. I did not submit the article
    to Capitalism Magazine.

        Question 2. In your testimony you indicated that your training is
    in ``atmospherics.'' Could you please explain this term more fully, and
    indicate your formal training in paleoclimatic studies and analysis?
        Response. My PhD thesis\1\ was on collisional-radiative properties
    of high-temperature, partially ionized nitrogen, oxygen, helium and
    hydrogen plasmas at conditions relevant to the Earth's atmosphere. This
    is why I mentioned that I had formal training in ``atmospheric and
    space physics'' in my oral remarks. If necessary, please consult my
    thesis advisor, Professor Joseph Kunc at kunc@usc.edu for further
    details about my educational background.
    ---------------------------------------------------------------------------
        \1\ Which was awarded the 1989 nation-wide IEEE Nuclear and Plasma
    Sciences Society Graduate Scholastic Award and the 1991's Rockwell
    Dennis Hunt Scholastic Award for ``the most representative PhD thesis
    work'' at the University of Southern California.
    ---------------------------------------------------------------------------
        I would add that the quality of knowledge about climate science or
    any other subject of interest must be judged on its own merits, and
    does not and must not be determined by invoking the amount of formal
    schooling or consensus viewpoints adopted by particular interest
    groups.
        My research interests and learning about paleoclimatology has been
    obtained mainly through the following individuals and sources:
        (1) Professor Eric Posmentier (Eric.S.Posmentier@Dartmouth.EDU),
    who is also my colleague.
        (2) Professor David Legates (legates@UDel.Edu), who is also my
    colleague.
        (3) Participation, both as a student and as lecturer, in numerous
    national and international workshops, conferences and summer schools
    including (a) the 1993's NATO Advanced Research workshop on ``Solar
    engine and its influence on terrestrial atmosphere and climate'', (b)
    the 1994's NASA-NOAA Summer School on Processes of Global Change, (c)
    the 1996's (French) CNRS ``Chaos et Fractales dans l'activite
    Solaire'', (d) the 2000's ``1st Solar and Space Weather Euroconference:
    The Solar Cycle and Terrestrial Climate,'' and other specialized
    meetings.
        (4) Many other scientists also have been helpful in my eager
    learning of the subject: the late Professor Jean Grove (Girton College,
    Cambridge University), Professor Jim Kennett (University of California
    Santa Barbara), Professor David J. A. Evans (University of Glasgow),
    Professor Lowell Stott (University of Southern California), Professor
    Hong-Chun Li (University of Southern California), Professor Reid Bryson
    (University of Wisconsin), Professor Henri Grissino-Mayer (University
    of Kentucky), Professor Emi Ito (University of Minnesota), Dr. ShaoPeng
    Huang (University of Michigan), Dr. Zhonghui Liu (Brown University),
    Dr. Ming Tang (Institute of Geology and Geophysics, Chinese Academy of
    Sciences), Dr. Yang Bao (Cold and Arid Regions Environmental and
    Engineering Research Institute, Chinese Academy of Sciences), and
    Professor Bin Wang (University of Hawaii).

        Question 3. Do you maintain that the proxy-based temperature
    reconstructions of the Mann and colleagues do not extend into the
    latter half of the 20th century?
        Response. The proxy-based temperature reconstructions for the
    Northern Hemisphere by Mann et al. (1998, Nature, vol. 392, 779-782)
    and Mann et al. (1999, Geophysical Research Letters, vol. 26, 759-762)
    extend from 1400-1980 and 1000-1980, respectively. So it is true that
    those proxy-based temperature series did not cover the 1981-2000
    interval of the late 20th century.
        Here is what close colleagues and co-authors (Bradley and Hughes)
    of Professor Mann admitted in their independent (i.e., without Prof.
    Mann as co-author) and updated publication, ``A caveat to [our]
    conclusion [about northern hemisphere temperature change over the last
    1000 years] is that the current proxy-based reconstructions do not
    extend to the end of the 20th century, but are patched on to the
    instrumental record of the last 2-3 decades [emphasis added]. This is
    necessary because many paleo data sets were collected in the 1960's and
    1970's, and have not been up-dated [NOTE: this statement by Bradley et
    al. (2003) referred primarily to the tree-ring data base from the
    International Tree-Ring Data base.], so a direct proxy-based comparison
    of the 1990's with earlier periods is not yet possible.'' [p. 116 of
    Bradley et al., 2003, In: Alverson, K., R.S. Bradley and T.F. Pedersen
    (eds.) Paleoclimate, Global Change and the Future. Springer Verlag,
    Berlin, 105-149]
        Agreeing with discussion on p. 260-261 of Soon et al. (2003),
    Bradley et al. (2003) cautioned that ``in the case of tree rings from
    some areas in high latitudes, the decadal time-scale climatic
    relationships prevalent for most of this century appear to have changed
    in recent decades, possibly because increasing aridity &/or snowcover
    changes at high latitudes may have already transferred the ecological
    responses of trees to climate (cf. Jacoby and D'Arrigo 1995; Briffa et
    al. 1998). For example, near the northern tree limit in Siberia, this
    changing relationship can be accounted for by a century-long trend to
    greater winter snowfall. This has led to delayed snowmelt and thawing
    of the active layer in this region of extensive permafrost, resulting
    in later onset of the growing season (Vaganov et al. 1999). It is not
    yet known how widely this explanation might apply to the other regions
    where partial decoupling has been observed, but regardless of the
    cause, it raises the question as to whether there might have been
    periods in the past when the tree ring-climate response changes, and
    what impact such changes might have on paleotemperature reconstructions
    based largely on tree ring data.'' (p. 116-117).
        Bradley et al. (2003) also worried that ``Paleoclimate research has
    had a strong northern hemisphere, extra-tropical focus (but even there
    the record is poorly known in many areas before the 17th century).
    There are very few high resolution paleoclimatic records from the
    tropics, or from the extra-tropical southern hemisphere, which leaves
    many questions (such as the nature of climate in Medieval times)
    unanswered.'' (p. 141). Bradley et al. continued ``All large-scale
    paleotemp-
    erature reconstructions suffer from a lack of data at low latitudes. In
    fact, most ``northern hemisphere'' reconstructions do not include data
    from the southern half of the region (i.e. [missing comma] areas south
    of 30N). Furthermore, there are so few data sets from southern
    hemisphere that it is not yet possible to reconstruct a meaningful
    ``global'' record of temperature variability beyond the period of
    instrumental records. For the northern hemisphere records, it must be
    recognized that the errors estimated for the reconstructions of Mann et
    al. (1999) and Briffa et al. (2001) are minimum estimates, based on the
    statistical uncertainties inherent in the methods used. These can be
    reduced by the use of additional data (with better spatial
    representation) that incorporate stronger temperature signals. However,
    there will always be additional uncertainties that relate to issues
    such as the constancy of the proxy-climate function over time, and the
    extent to which modern climate modes (i.e., those that occurred during
    the calibration interval) represent the full range of climate
    variability in the past [i.e., similar unresolved research questions
    had been raised in p. 239-242 and p. 258-264 of Soon et al. 2003].
    There is evidence that in recent decades some high latitude trees no
    longer capture low frequency variability as well as in earlier decades
    of the 20th century (as discussed below in Section 6.8) which leads to
    concerns over the extent to which this may have also been true in the
    more distant past. If this was a problem (and currently we are not
    certain of that) it could result in an inaccurate representation of low
    frequency temperature changes in the past. Similarly, if former
    climates were characterized by modes of variability not seen in the
    calibration period, it is unlikely that the methods now in use would
    reconstruct those intervals accurately. It may be possible to constrain
    these uncertainties through a range of regional studies (for example,
    to examine modes of past variability) and by calibration over different
    time intervals, but not all uncertainty can be eliminated and so
    current margins of error must be considered as minimum estimates
    [meaning the actual range of error is larger than shown in Mann et al.
    1999 or the IPCC TAR's charts].'' (p. 114-115).
        It is also very important to heed warnings and cautions from other
    serious researchers about not over stating the true confidence of a
    reconstructed climatic result based on indirect proxies. Esper et al.
    (2003, Climate Dynamics, vol. 21, 699-706) modestly apprised of the
    current situation in reconstructing long-term climatic information from
    tree rings: ``Although these long-term trends agree well with ECS
    [i.e., Esper, Cook, Schweingruber in 2002, Science, vol. 295, 2250-
    2253], the amplitude of the multi-centennial scale variations is,
    however, not understood. This is because (1) no single multi-centennial
    scale chronology could be built that is not systematically biased in
    the low frequency domain, and (2) no evidence exists that would support
    an estimation of the biases either in the LTM [Long-term mean
    standardization] nor in the RCS [Regional curve standardization] multi-
    centennial chronologies. Consequently, we also avoided providing formal
    climate calibration and verification statistics of the chronologies.
    Note also that the climate signal of the chronologies' low frequency
    component could not be statistically verified anyway. This is because
    the high autocorrelations, when comparing lower frequency trends,
    significantly reduce the degrees of freedom valid for correlation
    analyses. We believe that a formal calibration/verification/transfer
    function approach would leave the impression that the long-term climate
    history for the Tien Shan [i.e., the location of Esper and five
    colleagues' study] is entirely understood, which is not the case.
    Further research is needed to estimate the amplitude of temperature
    variation in the Alai Range [south of Kirghizia] over the last
    millennium.'' (p. 705)

        Question 4. Do you claim that the Mann study does not reconstruct
    regional patterns of temperature change in past centuries?
        Response. In Soon et al. (2003, Energy & Environment, vol. 14, 233-
    296), I and my colleagues cautioned that the regional temperature
    patterns resulted from Mann and colleagues' methodology are too
    severely restricted by the calibration particular, we are concerned
    that the regional (and hence larger spatial-scale averages) variability
    of temperature on multidecadal and centennial time scales deduced from
    such a method will be underestimated.
        Recently, the methodology of Mann et al. (1998) has been seriously
    challenged by McIntyre and McKitrick (2003, Energy & Environment, vol.
    14, 751-771) in that ``poor data handling, obsolete data and incorrect
    calculation of principal components'' were shown as the errors and
    defects of Mann et al's. paper. The exchange between Mann and
    colleagues and McIntyre and McKitrick is ongoing, but the use of
    obsolete data is a clear case of misrepresentation of regional basis of
    change in Mann et al's work. Further problems in Mann et al. (1998) are
    outlined under Question No. 13 below. Additional documentation
    (including responses by Prof. Mann and his colleagues) and updates can
    be found in http://www.uoguelph.ca/rmckitri/research/trc.html.

        Question 5. Do you maintain that the Mann study extrapolated global
    temperature estimates from the northern hemisphere?
        Response. I have not seen any global temperature curves presented
    in the two earlier studies by Mann et al. (1998 and 1999). But please
    consider the deep concerns about the lack of proxy data especially over
    the tropics (30N to 30S) and the southern hemisphere raised by Soon et
    al. (2003) and even in the independent paper by Professor Mann's close
    colleagues and co-authors (Bradley and Hughes), i.e., in Bradley et al.
    (2003), discussed under Question No. 3 above.
        ``Global'' temperature estimates, based on indirect climate
    proxies, from 200-1980 were shown in Mann and Jones (2003, Geophysical
    Research Letters, vol. 30 (15), 1820) as Figure 2c. But I am unsure if
    the temperature series presented by Mann and Jones (2003) could
    adequately represents the variability over the whole globe since it was
    openly admitted that the proxies used covered only 8 ``distinct
    regions'' in the Northern Hemisphere and 5 for the Southern Hemisphere
    (see the coverage of proxies shown in Figure 1 of Mann and Jones,
    2003).
        More importantly, Soon et al. (2004, Geophysical Research Letters,
    vol. 31, L03209) showed that the 40-year smoothed instrumental
    temperature trend for the Northern Hemisphere shown as Figure 2a of
    Mann and Jones (2003) has a physically implausible high value at year
    2000 (see more discussion in Question No. 6 below). We caution that the
    extremely rapid rate of warming trend of 1 to 2.5+ C per decade implied
    by the published results by Mann and his colleagues over the last one
    to 2 years [comparing Mann and Jones (2003) with both Mann (2002,
    Science, vol. 297, 1481-1482) and Mann et al. (2003, Eos, 84(27), 256-
    257)], is most likely due to the artifacts of methodology and their
    procedure of trend smoothing. I am submitting the pdf file (SLB-GRL04-
    NHtempTrend.pdf) of Soon et al. (2004) for the record of the committee.

        Question 6. Do you maintain that historical and instrumental
    temperature records that are available indicate colder northern
    hemisphere temperature conditions than the Mann et al northern
    hemisphere temperature reconstruction in the past centuries?
        Response. I am not sure about the meaning of this question. But
    when contrasted with borehole-based reconstruction, the Northern
    Hemisphere terrestrial temperatures produced by Mann et al. (1998,
    1999) over the last 500 years may have been too warm by about 0.4:+ C
    during the 17th-18th century (see Huang et al. 2000, Nature, vol. 403,
    756-758). Recent attempts by Mann et al. (2003, Journal of Geophysical
    Research, vol. 108. (D7), 4203) and Mann and Schmidt (2003, Geophysical
    Research Letters, vol. 30 (12), 1607) to rejustify and defend the Mann
    et al. (1998, 1999) results have been shown to be either flawed or
    invalid by Chapman et al. (2004, Geophysical Research Letters, vol. 31,
    L07205) and by Pollack and Smerdon (2003, Geophysical Research Abstract
    of EGS, vol. 6, 06345). The eventual fact will no doubt emerge with
    increased understanding, but Chapman et al. (2004) warned that ``A
    second misleading analysis made by Mann and Schmidt [2003] concerns use
    of end-points in reaching a numerical conclusion. . . . It is based on
    using end points in computing changes in an oscillating time series,
    and is just bad science.''
        With regard to instrumental thermometer data of the past 100-150
    years, it is important to note that Soon et al. (2004) has recently
    shown that the 40-year smoothed Northern Hemisphere temperature trend
    shown in Mann and Jones (2003) has a physically implausible high value
    at the year 2000 endpoint especially when studied in context with
    previous published results by Mann et al. (2003, Eos, vol. 84 (27),
    256-257) and Mann (2002, Science, vol. 297, 1481-1482). This important
    updated information, admittedly with the benefit of hindsight, together
    with the works by Chapman et al. (2004) and McIntyre and McKitrick
    (2003), showed clearly that the Northern Hemisphere temperature trends,
    either proxy-based or instrumental, derived by Mann et al. (1998, 1999)
    and Mann and Jones (2003) are not reliable.

        Question 7. Is it your understanding that during the mid-Holocene
    optimum period (the period from 4000-7000 B.C.) that annual mean global
    temperatures were more than a degree C warmer than the present day?
        Response. Again, I am not sure if there are sufficient proxy data
    that would allow a meaningful quantitative estimate of annual mean
    global temperatures back six to nine thousand years. But in a new paper
    for the Quaternary Science Reviews, Darrell Kaufman and 29 co-authors
    (2004, Quaternary Science Reviews, vol. 23, 529-560) found that indeed
    there are clear evidence for warmer than present conditions during the
    Holocene at 120 out of 140 sites they compiled across the Western
    Hemisphere of the Arctic. Kaufman et al. (2004) estimated that, at the
    16 terrestrial sites where quantitative data are available, the local
    Holocene Thermal Maximum summer temperatures were about
    1.60.8+ C higher than the average of the 20th century. The
    coarse temperature map sketched on the NOAA's Paleoclimatology web
    site: http://www.ngdc.noaa.gov/paleo/globalwarming/images/polarbigb.gif
    suggests that the summer temperatures 6000 years ago may have been 2 to
    4+ C warmer than present in the other sector (Eastern Hemisphere) of
    the Arctic.

        Question 8. As a climatologist, can you explain what kind of
    quantitative analysis it takes to determine whether or not the last 50
    years has been unusually warm compared to the last 1000 years?
        Response. The theoretical requirement is fairly simple: (a) find
    local and regional proxies that are sensitive to variations of
    temperature on timescales of decade, several decades and century; (b)
    have sufficient spatial coverage of these local and regional proxies.
    Then one would be able to compare the last 50 years of the 1000-year
    record with the previous 950 years.
        Soon et al. (2003) had indeed initiated an independent effort in
    this direction and concluded that a truly global or hemispheric
    averaged temperature record for the past 1000 years is not yet
    forthcoming because of the large and disparate range of the indirect
    local and regional proxies to temperature such that a robust ability of
    different proxies in capturing all the necessary scales of variability
    cannot yet be confirmed. The main problem I foresee in having any
    definitive answers for now is related to the fact that the statistical
    association of each proxy to climatic variables like temperature can
    itself be variable and changing depending on the location and time
    interval. But I am not sure if the sole focus on temperature as the
    measure of ``climate'' is sensible if not unnecessarily narrow.
        In Soon et al. (2003), we consider climate to be more than just
    temperature so we did not narrowly restrict ourselves to only
    temperature-sensitive proxies. For example, in addition to temperature,
    we are equally concerned about expansion and reduction of forested and
    desert-prone areas, tree-line growth limit, sea ice changes, balances
    of ice accumulation and ablation in mountain glaciers and so on. When
    studying the ice balance for a glacier, it is important to insist that
    although glaciers are very important indicators of climate change over
    a rather long time-scale, they are not simply thermometers as often
    confused by heated discussion pointing to evidence for global warming
    by carbon dioxide (see additional discussion on factors, especially
    atmospheric carbon dioxide, in determining Earth's climate and its
    change under Questions No. 19, 20, 25, 30 and 35 below). Examples
    include statements by Will Stefen, director of the International
    Geosphere-Biosphere Program, ``Tropical glaciers are a bellweather of
    human influence on the Earth system'' (quoted in the article ``The
    melting snows of Kilimanjaro'' by Irion, 2001, Science, vol. 291, 1690-
    1691) or by Professor Lonnie Thompson, Ohio State University,

              ``We have long predicted that the first signs of changes
            caused by global warming would appear at the few fragile, high-
            altitude ice caps and glaciers within the tropics . . . [t]hese
            findings confirm those predictions. We need to take the first
            steps to reduce carbon dioxide emissions. We are currently
            doing nothing. In fact, as a result of energy crisis in
            California--and probably in the rest of the country by this
            summer--we will be investing even more in fuel-burning power
            plants. That will put more power in the grid but, at the same
            times it will add carbon dioxide to the atmosphere, amplifying
            the problem'' (quoted in Ohio State University's press release,
            http://www.acs.ohio-state.edu/units/research/archive/
            glacgone.htm).

        A clarification about the physical understanding of modern glacier
    retreats and climate change, especially those on Kilimanjaro, is
    necessary and has been forthcoming with important research progress.
    First, Molg et al. (2003, Journal of Geophysical Research, vol. 108
    (D23), 4731) recently concluded that their study:

            ``highlights that modern glacier retreat on Kilimanjaro is much
            more complex than simply attributable to `global warming only',
            a finding that conforms with the general character of glacier
            retreat in the global tropic [Kaser, 1999]: a process driven by
            a complex combination of changes in several different climatic
            parameters . . . with humidity-related variables dominating
            this combination.''

    In another new paper for the International Journal of Climatology,
    Kaser et al. (2004, International Journal of Climatology, ``Modern
    glacier retreat on Kilimanjaro as evidence of climate change:
    Observations and facts'', vol. 24, 329-339; available from http://
    geowww.uibk.ac.at/glacio/LITERATUR/index.html) provided clear answers
    that neither added longwave radiation from a direct addition of
    atmospheric CO2 nor atmospheric temperature were the key
    variables for the observed changes, as revealed in this long but highly
    informative passage:

              ``Since the scientific exploration of Kilimanjaro began in
            1887, when Hans Meyer first ascended the mountain (not to the
            top at this time, but to the crater rim), a central theme of
            published research has been the drastic recession of
            Kilimanjaro's glaciers (e.g., Meyer, 1891, 1900; Klute, 1920;
            Gilman, 1923; Jager, 1931; Geilinger, 1936; Hunt, 1947; Spink,
            1949; Humphries, 1959; Downie and Wilkinson, 1972; Hastenrath,
            1984; Osmastion, 1989; Hastenrath and Greischar, 1997). Early
            reports describe the formation of notches, splitting up and
            disconnection of ice bodies, and measurements of glacier snout
            retreat on single glaciers, while later books and papers
            advance to reconstructing glacier surface areas. . . . Today,
            as in the past, Kilimanjaro's glaciers are markedly
            characterized by features such as penitentes, cliffs (Figure
            3a/b) [not reproduced here], and sharp edges, all resulting
            from strong differential ablation. These features illustrate
            the absolute predominance [emphasis added] of incoming
            shortwave radiation and latent heat flux in providing the
            energy for ablation (Kraus, 1972). A positive heat flux from
            either longwave radiation or sensible heat flux, if available,
            would round-off and destroy the observed features within a very
            short time ranging from hours to days. On the other hand, if
            destroyed, the features could only be sculptured again under
            very particular circumstances and over a long time. Thus, the
            existence of these features indicates that the present summit
            glaciers are not experiencing ablation due to sensible heat
            (i.e., from positive air temperature). Additional support for
            this is provided by the Northern Icefield air temperature
            recorded from February 2000 to July 2002, which never exceeded
            -1.6+ C, and by the presence of permafrost at 4,700 m below
            Arrow Glacier on the western slope . . .''

    Kaser et al. (2004) continue with this ``synopsis of interpretations
    and facts'':

              ``A synopsis of (i) proxy data indicating changes in East
            African climate since ca. 1850, (ii) 20th century instrumental
            data (temperature and precipitation), and (iii) the
            observations and interpretations made during two periods of
            fieldwork (June 2001 and July 2002) strongly support the
            following scenario. Retreat from a maximum extent of
            Kilimanjaro's glaciers started shortly before Hans Meyer and
            Ludwig Purtscheller visited the summit for the first time in
            1889, caused by an abrupt climate change to markedly drier
            conditions around 1880. Intensified dry seasons accelerated
            ablation on the respectively illuminated vertical walls left in
            the hole on top by Reusch Crater as a result of volcanic
            activity [emphasis added]. The development of vertical features
            may also have started on the outer margins of the plateau
            glaciers before 1900, primarily as the formation of notches, as
            explicitly reported following field research in 1898 and 1912
            (Meyer, 1900; Klute, 1920). A current example of such a notch
            development is the hole in the Northern Icefield (see Figure
            2). Once started, the lateral retreat was unstoppable,
            maintained by solar radiation despite less negative mass
            balance conditions on horizontal glacier surfaces, and will
            come to an end only when the glaciers on the summit plateau
            have disappeared. This is most probable within next decades, if
            the trend revealed in Figure 1 continues. Positive air
            temperatures have not contributed to the recession process on
            the summit so far. The rather independent slope glaciers have
            retreated far above the elevation of their thermal readiness,
            responding to dry conditions. If present precipitation regime
            persists, these glaciers will most probably survive in
            positions and extents not much different from today. This is
            supported by the area determinations in Thompson's et al.
            (2002) map, which indicate that slope glaciers retreated more
            from 1912 to 1952 than since then. From a hydrological point of
            view, melt water from Kibo's glaciers has been of little
            importance to the lowland in modern times. Most glacier
            ablation is due to sublimation, and where ice does melt it
            immediately evaporates into the atmosphere. Absolutely no signs
            of runoff can be found on the summit plateau, and only very
            small rivers discharge from the slope glaciers. Rainfall
            reaches a maximum amount at about 2,500 m a.s.l. [above sea
            level] (Coutts, 1969), which primarily feeds the springs at low
            elevation on the mountain; one estimate attributes 95 percent
            of such water to a forest origin (Lambrechts et al., 2002). The
            scenario presented offers a concept that implies climatological
            processes other than increased air temperature [emphasis added]
            govern glacier retreat on Kilimanjaro in a direct manner.
            However, it does not rule out that these processes may be
            linked to temperature variations in other tropical regions,
            e.g., in the Indian Ocean (Latif et al., 1999; Black et al.,
            2003).''

        Lindzen (2002, Geophysical Research Letter, vol. 29, paper
    2001GL014360) further added that ``Recent papers show that deep ocean
    temperatures have increased somewhat since 1950, and that the increase
    is compatible with predictions from coupled GCMs [General Circulation
    Models]. The inference presented is that this degree of compatibility
    constitutes a significant test of the models. . . . [But] it would
    appear from the present simple model (which is similar to what the IPCC
    uses to evaluate scenarios) that the ocean temperature change largely
    reflects only the fact that surface temperature change is made to
    correspond to observations, and says almost nothing about model climate
    sensitivity. . . . It must be added that we are dealing with observed
    surface warming that has been going on for over a century. The oceanic
    temperature change [at depth of 475 m or so] over the period reflects
    earlier temperature change at the surface. How early depends on the
    rate at which surface signals penetrate the ocean.'' In other words,
    the recently noted warming of the deeper ocean is not a proof of global
    surface and atmospheric warming by increasing CO2 in the air
    because the parameters of climate sensitivity and rate of ocean heat
    uptake are not sufficiently well quantified. In addition, if the
    earlier oceanic surface temperature warming mentioned by Lindzen were
    indeed initiated and occurred substantially long ago, then there would
    be no association of that change to man-made CO2 forcing.

        Question 9. The IPCC has found that the late 20th century is the
    warmest period in the last 1000 years, for average temperature in the
    northern hemisphere. Does your paper provide a quantitative analysis of
    average temperatures for the northern hemisphere for this specific time
    period--that is, for the later half of the 20th century?
        Response. It should be understood that (1) the conclusion of the
    IPCC Working Group I's Third Assessment Report (2001; TAR), (2) the
    evidence shown in Figure 1b of the Summary for Policymaker, (3) Figure
    5 of the Technical Summary, and (4) Figure 2.20 in Chapter 2 of TAR
    were all derived directly from the conclusion in Mann et al. (1999) and
    Figure 3a of Mann et al. (1999). Therefore all comments and criticisms
    presented in this Q&A about Mann et al. (1999) apply to the IPCC TAR's
    conclusion. In addition, Soon et al. (2004) recently cautioned that the
    40-year smoothed northern hemisphere temperature trend shown in Figure
    2.21 of TAR (2001) cannot be replicated according to the methodology
    described in the caption of Figure 2.21. The failure in replication
    introduces a significant worry about the actual quality of scientific
    efforts behind the production of Figure 2.21 in TAR (2001).
        The answer to the second part of your direct question is no. Here
    are the related reasons why a confident estimate of the averaged
    northern hemisphere temperature for the full 1000 years (including the
    full 20th century) is not yet possible, despite what had been claimed
    by Mann et al. (1999). First, several authors, including those detailed
    in section 5.1 of Soon et al. (2003) and those pointed out in Question
    No. 6, had shown that the 1000-year series of mathematical temperature
    derived by Mann et al. (1999) has significantly underestimated the
    multidecadal and centennial scale changes. Second, the focus of Soon et
    al. (2003) is to derive understanding of climatic change on local and
    regional spatial scales, instead of over the whole northern hemisphere
    per se, because those are the most relevant measures, in practical
    sense, of change. In addition, we provided the first-order attempt to
    collect all available climate proxies relevant for local and regional
    climatic changes, but not restricted to temperature alone. But more
    pertinent to your question is the fact discussed in Soon et al. (2003)
    that different proxies respond with differing sensitivities to
    different climatic variables, seasons, plus spatial and temporal
    scales, so that a convenient derivation of a self-consistent northern
    hemisphere averaged annual mean temperature for the full 1000 years,
    desirable as the result may be, is not yet possible.

        Question 10. Does your paper provide any quantitative analysis of
    temperature records specifically for the last 50 years of the 20th
    century?
        Response. Soon et al. (2003) considered all available proxy records
    with no particular prejudice. If the individual proxy record covers up
    to the last 50 years of the 20th century, then quantitative comparisons
    are performed, mostly according to the statements from the original
    authors. Please consider some of the detailed quantitative discussion
    in section 4 of Soon et al. (2003) and the qualitative results compiled
    in Table 1 of that paper.

        Question 11. In an article in the Atlanta Journal Constitution
    (June 1, 2003), you were quoted as acknowledging during a question
    period at a previous Senate luncheon that your research does not
    provide a comprehensive picture of the Earth's temperature record and
    that you questioned whether that is even possible, and that you did
    not, ``. . . see how Mann and the others could `calibrate' the various
    proxy records for comparison.'' How then does your analysis provide a
    comprehensive picture of Earth's temperature record or have any bearing
    on the finding by the IPCC, that the late 20th century is the warmest
    in the last 1000 years?
        Response. Thank you for referencing the article. I must first state
    on the record that contrary to the claim in this Atlanta Journal
    Constitution (June 1, 2003) article http://www.ajc.com/business/
    content/business/0603/01warming.html, the writer, never, as claimed,
    conducted a telephone interview with me. No such conversation took
    place and I am rather shocked by this false claim. This fact has gone
    uncorrected until now.
        The strengths and weaknesses of my research works are fully
    discussed in Soon et al. (2003). The paper documented detailed local
    and regional changes in several climatic variables to try to obtain a
    broader understanding of climate variability. We concluded that:

              ``Because the nature of the various proxy climate indicators
            are so different, the results cannot be combined into a simple
            hemispheric or global quantitative composite. However,
            considered as an ensemble of individual observations, an
            assemblage of the local representations of climate establishes
            the reality of both the Little Ice Age and the Medieval Warm
            Period as climatic anomalies with worldwide imprints, extending
            earlier results by Bryson et al. (1963), Lamb (1965), and
            numerous other research efforts. Furthermore, these individual
            proxies are used to determine whether the 20th century is the
            warmest century of the 2nd Millennium at a variety of globally
            dispersed locations. Many records reveal that the 20th century
            is likely not the warmest nor a uniquely extreme climatic
            period of the last millennium, although it is clear that human
            activity has significantly impacted some local environments.''

        The question on the difficult problem of calibrating proxies of
    differing types and sensitivities to climatic variables is discussed in
    Soon et al. (2003) and some criticisms on the weaknesses of the
    reconstruction by Mann et al. (1999) or the related IPCC TAR's
    conclusion are listed especially under Questions No. 6 and 9.

        Question 12. Do you believe that appropriate statistical methods do
    not exist for calibrating statistical predictors, including climate
    proxy records, against a target variable, such as the modern
    instrumental temperature record?
        Response. True progress in the field of paleoclimatology will
    certainly involve a better and more robust means of interpreting and
    quantifying the variations and changes seen in each high-resolution
    proxy record. The issue is not merely a problem awaiting solution
    through appropriate statistical methods like the EOF methodology
    adopted by Mann et al. (1998, 1999). On pp. 241-242 of Soon et al.
    (2003), we briefly outlined our straight-forward approach and
    contrasted it to the one used by Mann and colleagues that does not
    necessarily lead to results with physical meaning and reality.

        Question 13. In determining whether the temperature of the
    ``Medieval Warm Period'' was warmer than the 20th century, does your
    study analyze whether a 50-year period is either warmer or wetter or
    drier than the 20th century? If so, why is it appropriate to use
    indicators of drought and precipitation directly to draw inferences of
    past temperatures? Please list peer-reviewed works that specifically
    support the use of these indicators for inferring past temperature.
        Response. The detailed discussion behind our usage of the term
    ``Medieval Warm Period'' or ``Little Ice Age'' was described in Soon et
    al. (2003). We are mindful that the two terms should definitely include
    physical criteria and evidence from the thermal field. But we emphasize
    that great bias would result if those thermal anomalies were
    dissociated from hydrological, cryospheric, chemical, and biological
    factors of change. So indeed our description of a Medieval Climatic
    Anomaly (see a similar sentiment later reported by Bradley et al. 2003,
    Science, vol. 302, 404-405) in Soon et al. (2003) includes a warmer
    time that contains both drought or flooding conditions depending on the
    locations.
        With regard to the last part of your question, I would answer by
    detailing only one example--Mann et al (1998). This influential study
    used both direct precipitation measurements and precipitation proxies
    as temperature indicators. This study was indeed applied by the IPCC
    TAR (2001). These include historical precipitation measurements in 11
    grid cells, two coral proxies (reported in Mann et al. [1998] as
    precipitation proxies; see http://www.ngdc.noaa.gov/paleo/ei/data--
    supp.html for this and following references), two ice core proxies, 3
    reconstructions of spring precipitation in southeast United States by
    Stahle and Cleaveland from tree ring data, 12 principal component
    series for tree rings in southwestern United States and Mexico reported
    as precipitation proxies by Stahle and Cleaveland (and Mann et al.
    1998) and one tree ring series in Java--making a total of 31
    precipitation series used as proxies in temperature reconstruction by
    Mann et al. (1998). In this peer-reviewed article, for the
    precipitation data in a grid cell in New England, the researchers
    apparently used historical data from Paris, France (please see Figure 2
    of McIntyre and McKitrick, 2003 and their discussion on pp. 758-759).
    For a grid cell near Washington DC, the researchers used historical
    data from Toulouse, France. For a grid cell in Spain, the researchers
    used precipitation data from Marseilles, France. Of the 11
    precipitation series used in Mann et al. (1998), only one series
    (Madras, India) is correctly located. The precipitation data used by
    these authors cannot be identified in the source cited in paper Mann et
    al. (1998). While precipitation data and precipitation-related proxies
    can be instructive in providing information on past distribution of
    moisture and circulation patterns (and thus temperature), it is
    important to correctly identify the series used and important not to
    use data from the wrong continent for historical reconstructions.

        Question 14. Do you maintain that any two 50-year periods that
    occur within a multi-century interval can be considered 'coincident'
    from a climatic point of view?
        Response. The question raised here about the connection of any two
    50-year periods in any two regions to be related from climatic point of
    view is both important and interesting. But the answer will be strongly
    dependent on the nature of forcings and feedbacks involved. If longer-
    term cryospheric or oceanic processes are involved then the answer
    would be yes.

        Question 15. Do your two recent studies employ an analysis (that
    is, a statistical or analytical operation performed upon numerical
    data) of a single proxy climate record?
        Response. The meaning of this question is not entirely clear to me.
    But I would say yes under the context of what is being said.

        Question 16. Has your study produced a quantitative reconstruction
    of past temperature patterns? Do you have a measure of uncertainty or
    verification in your description of past temperatures?
        Response. The results and conclusion of Soon et al. (2003) are best
    judged by the paper itself. Quantitative assessments of local and
    regional changes through the climatic proxies are discussed in section
    4 of that paper as well as some qualitative picture described in
    Figures 1, 2 and 3 of that paper. Again, Soon et al. (2003) did not
    tried to distill all the collected proxies down to produce a strict
    temperature-only result since we are interested in a broader
    understanding of climate variability. Part of the answers given under
    Questions No. 9 and 11 can help elaborate what was done by Soon et al.
    (2003). I would also like to direct your attention to the two warnings
    listed under Question No. 3 by Bradley et al. (2003) and Esper et al.
    (2003) concerning any undue, over confidence in promoting quantitative
    certainties in the reconstruction of past temperatures through highly
    imprecise black boxes of indirect proxies.

        Question 17. Your study indicates that you have compiled the
    results of hundreds of previous paleo-climate studies. Have you
    verified your interpretation of the hundreds of studies with any of the
    authors/scientists involved in those studies? If so, how many?
        Response. Specific authors and scientists that provided help in our
    work were listed in the acknowledgement section (p. 272) of Soon et al.
    (2003). We have also received generous help and comments from several
    scientists who are certainly highly qualified in terms of paleoclimatic
    studies. But the ultimate quality and soundness of our research shall
    always be our own responsibility.
        In the September 5, 2003 Chronicle for Higher Education article (by
    Richard Monastersky), there were indeed two very serious accusations
    that suggested that Soon et al. (2003) had misrepresented or abused the
    conclusions by two original authors whose work we had cited. Our
    corrections and explanations to these unfortunately false claims can be
    studied from the documentation listed in the URL http://cfa-
    www.harvard.edu/wsoon/ChronicleHigherEducation03-d (read especially
    Sep12-lettoCHE3.doc and Sep12-lettoCHE4.doc).

        Question 18. What was earth's climate like the last time that
    atmospheric concentrations of carbon dioxide were at today's levels or
    about 370 parts per million (ppm) and what were conditions like when
    concentration were at 500 ppm, which will occur around 2060 or so?
        Response. Co-answer to this question is listed under Question No.
    19 below.

        Question 19. Please describe any known geologic precedent for large
    increases of atmospheric CO2 without simultaneous changes in
    other components of the carbon cycle and the climate system.
        Response. My July 29, 2003 testimony was about the climate history
    of the past 1000 years detailed in Soon et al. (2003) rather than any
    potential (causal or otherwise) relationship between atmospheric carbon
    dioxide and climate. The fact remains that the inner working of the
    global carbon cycle and the course of future energy use are not
    sufficiently understood or known to warrant any confident prediction of
    atmospheric CO2 concentration at year 2060. Please consider
    co-answer to this question under Question No. 25 below.
        However, it is abundantly obvious that atmospheric CO2
    is not necessarily an important driver of climate change. It is indeed
    a puzzle that despite the relative low level of atmospheric CO2
    of no more than 300 ppm in the past 320-420 thousand years (Kawamura et
    al., 2003, Tellus, vol. 55B, 126-137) compared to the high levels of
    330-370 ppm since the 1960's there is the clear suggestion of
    significantly warmer temperatures at both Vostok and Dome Fuji, East
    Antarctica, during the interglacials at stage 9.3 (about 330 thousand
    years before present; warmer by about 6+ C) and stage 5.5 (about 135
    thousand years before present; warmer by about 4.5+ C) than the most
    recent 1000 years (see Watanabe et al., 2003, Nature, vol. 422, 509-
    512; further detailed discussion on environmental changes in Antartica
    over the past 1000 years or so, including the most recent 50 years can
    be found in section 4.3.4 or pp. 256-257 of Soon et al. 2003).
        But there are important concerns about the retrieval of information
    on atmospheric CO2 levels from ice cores. Jaworowski and
    colleagues (1992, The Science of the Total Environment, vol. 114, 227-
    284) explained that:

              ``Ice is not a rigid material suitable for preserving the
            original chemical and isotopic composition of atmospheric gas
            inclusion. Carbon dioxide in ice is trapped mechanically and by
            dissolution in liquid water. A host of physico-chemical
            processes redistribute CO2 and other air gases
            between gaseous, liquid and solid phases, in the ice sheets in
            situ, and during drilling, transport and storage of the ice
            cores. This leads to changes in the isotopic and molecular
            composition of trapped air. The presence of liquid water in ice
            at low temperatures [`even below--70+ C'] is probably the most
            important factor in the physico-chemical changes. The permeable
            ice sheet with its capillary liquid network acts as a giant
            sieve which redistributes elements, isotopes and micro-
            particles. Carbon dioxide in glaciers is contained: (1) in
            interstitial air in firn; (2) in air bubbles in ice; (3) in
            clathrates; (4) as a solid solution in ice crystals; (5)
            dissolved in intercrystalline veins and films of liquid brine;
            and (6) in dissolved and particulate carbonates. Most of the
            CO2 is contained in ice crystals and liquids, and
            less in air bubbles. In the ice cores it is also present in the
            secondary gas cavities, cracks, and in the traces of drilling
            fluids.
              The concentration of CO2 in air recovered from the
            whole ice is usually much higher than that in atmospheric air.
            This is due to the higher solubility of this gas in cold water,
            which is 73.5- and 35-times higher than that of nitrogen and
            oxygen, respectively. The composition of other atmospheric
            gases (N2, O2, Ar) is also different in
            ice and in air inclusions than in the atmosphere. Argon-39 and
            85Kr data indicate that 36-100 percent of air recovered from
            deep Antarctic ice cores is contaminated by recent atmospheric
            air during field and laboratory processing. Until about 1985,
            CO2 concentrations in gas recovered from primary air
            bubbles and from secondary gas cavities in pre-industrial and
            ancient ice were often reported to be much higher than in the
            present atmosphere. After 1985, only concentrations below the
            current atmospheric level were published. Our conclusion is
            that both these high and low CO2 values do not
            represent real atmospheric content of CO2.
              Recently reported concentrations of CO2 in primary
            and secondary gas inclusions from deep cores, covering about
            the last 160,000 years, are much below the current atmospheric
            level, although several times during this period the surface
            temperature was 2-4.5+ C higher than now. If these low
            concentrations of CO2 represented real atmospheric
            levels, this would mean (1) that CO2 had not
            influenced past climatic changes, and (2) that climatic changes
            did not influence atmospheric CO2 levels.'' (p. 272-
            273)

        Additional historical evidence reveals natural occurrences of
    large, abrupt climatic changes that are not uncommon and they occurred
    without any known causal ties to large radiative forcing change. Phase
    differences between atmospheric CO2 and proxy temperature in
    historical records are often not fully resolved; but atmospheric
    CO2 has shown the tendency to follow rather than lead
    temperature and biosphere changes (see e.g., Dettinger and Ghil, 1998,
    Tellus, vol. 50B, 1-24; Fischer et al., 1999, Science, vol. 283, 1712-
    1714; Indermuhle et al., 1999, Nature, vol. 398, 121-126).
        In addition, there have been geological times of global cooling
    with rising CO2 (during the middle Miocene about 12.5-14
    million years before present [Myr BP], for example, with a rapid
    expansion of the East Antarctic Ice Sheet and with a reduction in
    chemical weathering rates), while there have been times of global
    warming with low levels of atmospheric CO2 (such as during
    the Miocene Climate Optimum about 14.5-17 Myr BP as noted by Panagi et
    al., 1999, Paleocenoragphy, vol. 14, 273-292). A new study of
    atmospheric carbon dioxide over the last 500 million years (Rothman,
    2002, Proceedings of the (US) National Academy of Sciences, vol. 99,
    4167-4171) concluded that, ``CO2 levels have mostly
    decreased for the last 175 Myr. Prior to that point [CO2
    levels] appear to have fluctuated from about two to four times modern
    levels with a dominant period of about 100 Myr. . . . The resulting
    signal exhibits no systematic correspondence with geologic record of
    climatic variations at tectonic time scales.''

        Question 20. According to a study published in Science magazine,
    [B. D. Santer, M. F. Wehner, T. M. L. Wigley, R. Sausen, G. A. Meehl,
    K. E. Taylor, C. Amman, W. M. Washington, J. S. Boyle, and W.
    Bruggemann Science 2003 July 25; 301: 479-483], manmade emissions are
    partly to blame for pushing outward the boundary between the lower
    atmosphere and the upper atmosphere. How does that fit with the long-
    term climate history and what are the implications?
        Response. It should first be noted that Pielke and Chase (2004,
    Science, vol. 303, 1771b; and see p. 1771c by Santer et al. and
    additional counter-reply by Pielke and Chase, with input from John
    Christy and Anthony Reale, available as paper 278b at http://
    blue.atmos.colostate.edu/publications/reviewedpublications.shtml) had
    criticized and challenged Santer et al.'s claim and conclusion that,

            ``[o]ur results are relevant to the issue of whether the `real-
            world' troposphere has warmed during the satellite era. . . .
            The direct evidence is that in the ALL experiment [i.e.,
            climate model results that included changes in well-mixed
            greenhouse gases, direct scattering effects of sulfate
            aerosols, tropospheric and stratospheric ozone, solar total
            irradiance and volcanic aerosols; see more discussion below],
            the troposphere warms by 0.07+ C/decade over 1979-1999. This
            warming is predominantly due to increases in well-mixed
            greenhouse gases. . . . Over 1979-1999, roughly 30 percent of
            the increase in tropopause height in ALL is explained by
            greenhouse gas-induced warming of the troposphere.
            Anthropogenically driven tropospheric warming is therefore an
            important factor in explaining modeled changes in tropopause
            height.''

        In contrast, Pielke and Chase (2004) offered the observed evidence
    and concluded that

            ``[g]lobally averaged tropospheric temperature trends are
            statistically indistinguishable from zero. Thus, the elevation
            of the globally averaged tropopause report in [Santer et al.,
            2003] cannot be attributed to any detectable tropospheric
            warming over this period.'' In addition, ``the climate system
            is much more complex than defined by tropospheric temperature
            and tropopause changes. Linear trend analysis [in Santer et
            al., 2003] is of limited significance. Changes in global heat
            storage provide a more appropriate metric to monitor global
            warming than temperature alone.''

        Soon and Baliunas (2003, Progress in Physical Geography, vol. 27,
    448-455) had also previously outlined the incorrect fingerprint of
    CO2 forcing observed in even the best and sophisticated
    version of climate models thus far. A more general and comprehensive
    discussion about the fundamental difficulties on modeling the effects
    of carbon dioxide using current generation of climate models is given
    in Soon et al. (2001, Climate Research, vol. 18, 259-271). Thus, the
    new paper by Santer et al. (2003) does not supercede or overcome the
    difficulties with respect to General Circulation Climate Models raised
    in Soon and Baliunas (2003).
        Both the meaning and strength of the model-dependent results shown
    in Santer et al. (2003) remain doubtful and weak for several additional
    reasons.
        First, Figure 2 of Santer et al. (2003) itself confirmed that the
    modeled changes in tropopause height are caused mainly by large
    stratospheric cooling related to changes in stratospheric ozone (they
    admitted so even though their note No. 35 indicates that their
    numerical experiments did not separate tropospheric and stratospheric
    ozone changes) rather than by the well-mixed greenhouse gases that are
    supposed to be the subject of concern. Second, the model experiments of
    Santer et al. (2003) did not include changes in stratospheric water
    vapor which is known to be a significant factor for the observed
    stratospheric cooling (see e.g., Forster and Shine, 1999, Geophysical
    Research Letters, vol. 26, 3309-3312). Third, the failure to account
    for stratospheric water vapor contradicted the documented significant
    increases of stratospheric water vapor in the past half-century from a
    variety of instrumentations (e.g., Smith et al, 2000, Geophysical
    Research Letters, vol. 27, 1687-1690; Rosenlof et al., 2001,
    Geophysical Research Letters, vol. 28, 1195-1198; though Randel et al.
    [2004, Journal of the Atmospheric Sciences, submitted] recently noted
    that unusually low water vapor has been observed in the lower
    stratosphere for 2001-2003). Fourth, the model experiments by Santer et
    al. (2003) had clearly neglected (see note No. 18 of that paper) the
    role of the Sun's ultraviolet radiation that is not only known to be
    variable (e.g., Fontenla et al. 1999, The Astrophysical Journal, vol.
    518, 480-499; White et al., 2000, Space Science Reviews, vol. 94, 67-
    74) but also known to exert important influence on both the chemistry
    and thermal properties in the stratosphere and troposphere (e.g.,
    Larkin et al., 2000, Space Science Reviews, vol. 94, 199-214).
        Finally, the physical representation of aerosol forcing (which
    should not be restricted to sulfate alone) in Santer et al. (2003) is
    clearly not comprehensive and at best highly selective. Early on,
    Russell et al. (2000, Journal of Geophysical Research, vol. 105, 14891-
    14898) cautioned that

            ``[o]ne danger of adding aerosols of unknown strength and
            location is that they can be tuned to give more accurate
            comparisons with current observations but cover up model
            deficiencies.''

    Anderson et al. (2003, Science, vol. 300, 1103-1104 and see also
    exchanges in Crutzen et al., 2003, vol. 303, 1679-1681) recently
    cautioned that:

            ``we argue that the magnitude and uncertainty of aerosol
            forcing may affect the magnitude and uncertainty of total
            forcing [i.e., `the global mean sum of all industrial-era
            forcings'] to a degree that has not been adequately considered
            in climate studies to date. Inferences about the causes of
            surface warming over the industrial period and about climate
            sensitivity may therefore be in error. . . . Unfortunately,
            virtually all climate model studies that have included
            anthropogenic aerosol forcing as a driver of climate change
            (diagnosis, attribution, and projection studies; denoted
            `applications' in the figure) have used only aerosol forcing
            values that are consistent with the inverse approach. If such
            studies were conducted with the larger range of aerosol
            forcings determined from the forward calculations, the results
            would differ greatly. The forward calculations raise the
            possibility that total forcing from preindustrial times to the
            present . . . has been small or even negative. If this is
            correct, it would imply that climate sensitivity and/or natural
            variability (that is, variability not forced by anthropogenic
            emissions) is much larger than climate models currently
            indicate. . . . In addressing the critical question of how the
            climate system will respond to this [anthropogenic greenhouse
            gases'] positive forcing, researchers must seek to resolve the
            present disparity between forward and inverse calculations.
            Until this is achieved, the possibility that most of the
            warming to date is due to natural variability, as well as the
            possibility of high climate sensitivity, must be kept open.
            [emphasis added]''

        To further understand the complexity of calculating aerosol
    forcing, Jacobson (2001, Journal of Geophysical Research, vol. 106,
    1551-1568) has to account for a total of 47 species ``containing
    natural and/or anthropogenic sulfate, nitrate, chloride, carbonate,
    ammonium, sodium, calcium, magnesium, potassium, black carbon, organic
    matter, silica, ferrous oxide, and aluminium oxide'' in his recent
    estimate of only the global direct radiative forcing by aerosols.
    (Jacobson [2001] found that the global direct radiative forcing by
    anthropogenic aerosols is only -0.12 W/m\2\ while the forcing by
    combined natural and anthropogenic sources is -1.4 W/m\2\.) There are
    also the indirect aerosol effects. Temperature or temperature change is
    clearly not the only practical measure of effects by aerosols. Haywood
    and Boucher (2000, Reviews of Geophysics, vol. 38, 513-543) stressed
    the fact that the indirect radiative forcing effect of the modification
    of cloud albedo by aerosols could range from -0.3 to -1.8 W/m\2\, while
    the additional aerosol influences on cloud liquid water content (hence,
    precipitation efficiency), cloud thickness and cloud lifetime are still
    highly uncertain and difficult to quantify (see e.g., Rotstayn and Liu,
    2003, Journal of Climate, vol. 16, 3476-3481). This is why one can
    easily appreciate the difficulties faced by Santer et al. (2003)
    because climate forcing by aerosols is not only known within a wide
    range of uncertainties but also to a large degree of unknown.
        Therefore, I conclude that in addition to the fundamental issues
    related to climate model representation of physical processes, papers
    like Santer et al. (2003) have also failed the basic requirement for
    internal consistencies in the accounting for potentially relevant
    climatic forcing factors and feedbacks. This is why I cannot comment on
    the implication of this particular study and the meaning of the study
    for long-term climate history.

        Question 21. In your testimony, you discussed there being
    ``warming'' and ``cooling'' for different periods. If you did not
    construct an integral across the hemisphere or a real timeline, don't
    your findings really just say there were some warm periods and cool
    periods, and therefore cannot speak to the issue of the rate of warming
    or cooling?
        Response. I am not sure about the meaning of this question and the
    quotes. My oral remark was merely referring to ``making an accurate
    forecast that includes all potential human-made warming and cooling
    effects.'' The detailed discussion about the climatic and environmental
    changes for the past 1000 years as deduced from the collection of
    proxies I had studied was given in Soon et al. (2003). I can certainly
    speak to the rate of warming or cooling at any given location or region
    when the available proxy, with sufficient temporal resolution, is known
    or proven to be temperature sensitive.

        Question 22. Is there any indication that regional climate
    variations are any larger or smaller at present than over the last 1000
    years (with 2003, for example, perhaps being a case with large regional
    variations from the normal)?
        Response. I would not recommend considering the pattern of change
    from a single year, i.e., 2003, and called it a climate change. But the
    fact is that in Soon et al. (2003) we had carefully studied individual
    proxy records from various locations and regions. As an example, the
    2000-year bottom-sediment record from Moon Lake, North Dakota, shows
    there is perhaps a distinct shift in the mode of hydrologic variability
    in the Northern Great Plain region starting around 1200 AD with the
    more recent period being more variable from the past. But, as indicated
    in the chart below, the author of this paper also noted that the severe
    droughts of the 1890's and 1930's around this area are ``eclipsed by
    more extensive droughts before the beginning of the instrumental
    period.''

    [GRAPHIC] [TIFF OMITTED] T2381.096

        Question 23. In your oral presentation, you talked about ``[h]aving
    computer simulation.'' Could you please explain what you [as in your
    original] computer simulation or modeling to which you are referring,
    and, (a) Has this model gone through the appropriate set of model
    intercomparison studies like the various othe global models? (b) What
    forcings have been used to drive it? (c) How does it develop regional
    climate variations, and are these comparable to observations? and, (d)
    How does it perform over the 20th century, for example?
        Response. I apologize for any potential confusions.
        In my oral remark, I said,

              ``The entirety of climate proxies over the last 1,000 years
            shows that over many areas of the world there has been, and
            continues to be, large climate changes. Those changes provide
            challenges for the computer simulations of climate. The full
            models, which explore the Earth region by region, can be tested
            against the natural patterns of change over the last 1,000
            years that are detailed by the climate proxies. Having computer
            simulations reproduce past patterns of climate, which has been
            influenced predominantly by natural factors, is key to making
            an accurate forecast that includes all potential human-made
            warming and cooling factors.''

        So in the context of what I said, this question is clearly
    misdirected by someone who did not understand my remark. I was speaking
    on the potential application of works like Soon et al. (2003) for
    improving our ability to calculate with confidence the potential
    effects from man-made factors by first and foremost having a climate
    model that can at least reproduce some of the observed local and
    regional changes of the past.
        Personally, I am also conducting my research through the help of
    several climate models (both simple and complex types) appropriate for
    my interests and I would certainly apply what I found in Soon et al.
    (2003) to my own future studies using climate models. Any additional
    comments will be beyond the simple context of my oral testimony. But,
    it may be useful to take note of the comments by Green (2002, Weather,
    vol. 57, 431-439):

              ``It has always worried me that simple models of climate do
            not seem to work very well. Experts on numerical models say
            that this is because the atmosphere is very complicated, and
            that large numerical models and computers are needed to
            understand it. I worry because I do not know what they have
            hidden in those models and the programs they use. I wonder what
            I can compare their models with. Not with each other because
            they belong to a sort of club, where to have a model that
            disagrees with everyone else's puts you outside. That is not a
            bad system, unless of course they are all wrong. Another
            curiosity of complicated models is that their findings are
            rarely used to improve the model that preceded them. I would
            have expected that the more complex model would show where the
            simpler one had got it wrong, and allow it to be corrected for
            that misrepresentation.''

        Question 24. Based on the various comments of your scientific
    colleagues regarding your paper, including the methodological flaws
    pointed out in that paper by the former editor-in-chief of Climate
    Research, are you planning any reworking of your study or any further
    studies in the paleoclimatic area?
        Response. The use of a phrase like ``methodological flaws'' is a
    very convenient attempt to dismiss the weight of scientific evidence
    presented in Soon et al. (2003) but unfortunately without any clear nor
    confirmable basis. Thus far, the only formal criticism of Soon et al.
    (2003) was by Mann et al. (2003, Eos, vol. 84(27), 256-257) and we had
    provided our response to that criticism in Soon et al. (2003b, Eos,
    vol. 84(44), 473-476). My research interest and work to fully discern
    and quantitatively describe the local and regional patterns of climate
    variability over the past 1000 years or so will certainly continue
    despite this mis-characterization.
        It should however not be left unnoticed that several very serious
    problems in Mann et al. (1998, 1999), Mann and Schmidt (2003) and Mann
    and Jones (2003) had been found recently. Those unresolved anomalies
    are outlined in my answers to your Questions No. 3, 4, 5, 6, 9 and 13.
    A careful reworking with a fully open access to all data as well as a
    fully disclosed transparency of the actual methodologies and detailed
    applications will be the next important step for paleoclimate
    reconstruction research.

        Question 25. You indicated that there would likely be relatively
    small climatic response to even substantial increases in the CO2
    concentration. Do you disagree with the radiation calculations that
    have been done and the trapped energy that they calculate, as per the
    peer-reviewed literature? If so, please explain.
        Response. First, please consider the above discussion on climate
    forcing factors and climate response sensitivities under Question No.
    20 as part of the answers to this question.
        Second, I do not believe that I had made any strong claim, one way
    or another, about the CO2 forcing and potential response in
    any specific quantitative term during my testimony (since factually no
    one can). I do want to comment, as in my response under Question No.
    19, that CO2, as a minor greenhouse gas, is not a
    determinant of Earth's climate and therefore not entirely obvious a
    driver of its change. Most calculations in peer-reviewed literature (or
    not) that focus on the CO2 factor indeed would only like us
    to believe that CO2, especially under the realm of radiative
    forcing, is the predominant factor for driving anomalous climate
    responses, while the unavoidable and very difficult core subject about
    the actual dynamical state of Earth's ``mean'' climate is ignored.
        Third, some 10 years ago, Lindzen (1994, Annual Review in Fluid
    Mechanics, vol. 26, 353-378) pointed out a rather serious internal
    inconsistency regarding the role of water vapor and clouds when the
    physics of greenhouse effect is normally evaluated even among expert
    scientists or expert sources of information. (See e.g., the comment
    ``without [the greenhouse effect], the planet would be 65 degrees
    colder'' by Jerry Mahlman in the February 2004 issue of Crisis
    Magazine, http://www.crisismagazine.com/february2004/feature1.htm) and
    the description of Greenhouse Effect in the EPA's ``global warming for
    kids'' webpage: http://www.epa.gov/globalwarming/kids/greenhouse.html.)
    Lindzen notes the ``artificial inevitability'' for the predominance of
    CO2 radiative forcing as a climatic factor in the following
    passage.

              ``In most popular depictions of the greenhouse effect, it is
            noted that in the absence of greenhouse gases, the Earth's mean
            temperature would be 255 K [about 0+ F], and that the presence
            of infrared absorbing gases elevates this to 288 K [59+ F]. In
            order to illustrate this, only radiative heat transfer is
            included in the schematic illustrations of the effect (Houghton
            et al. 1990, 1992) [IPCC reports]; this lends an artificial
            inevitability to the picture. Several points should be made
            concerning this picture: 1. The most important greenhouse gas
            is water vapor, and the next most important greenhouse
            substance consists in clouds; CO2 is a distant third
            (Goody & Yung 1989). 2. In considering an atmosphere without
            greenhouse substances (in order to get 255 K), clouds are
            retained for their visible reflectivity while ignored for their
            infrared properties. More logically, one might assume that the
            elimination of water would also lead to the absence of clouds,
            leading to a temperature of about 274 K [or 278 K depending on
            what value of the solar irradiation factor is used] rather than
            255 K. 3. Pure radiative heat transfer leads to a surface
            temperature of about 350 K rather than 288 K. The latter
            temperature is only achieved by including a convective
            adjustment that consists simply in adjusting vertical
            temperature gradient so as to avoid convective instability
            while maintaining a consistent radiative heat flux. . . . ``
            (p. 359-361)\2\
    ---------------------------------------------------------------------------
        \2\ A more pedagogical discussion of the greenhouse effect is given
    by Lindzen and Emanuel (2002) in Encyclopedia of Global Change,
    Environmental Change and Human Society, Volume 1, Andrew S. Goudie,
    editor in chief, p. 562-566, Oxford University Press, New York, 710 pp.

        Hu et al. (2000, Geophysical Research Letters, vol. 27, 3513-3516)
    added that as the sophistication of parameterization of atmospheric
    convection increases, there is a tendency for climate model sensitivity
    to variation in atmospheric CO2 concentration to decrease
    considerably. In Hu et al. (2000)'s study, the change is from a
    decrease in the averaged tropical warming of 3.3 to 1.6+ C for a
    doubling of CO2 that is primarily associated the
    corresponding decrease in the calculated total atmospheric column
    ---------------------------------------------------------------------------
    increase in water vapor from 29 percent to 14 percent.

        Question 26. If you accept those radiation calculations as valid,
    please explain why you seem to believe that the energy trapped by the
    greenhouse gases will have a small effect whereas you seem to believe
    that small changes in solar energy will have very large climatic
    effects?
        Response. In addition to my answers under Questions No. 19, 20 and
    25 above, I would like to point out that the Sun's radiation is not
    only variable but it varies in the ultraviolet part of the
    electromagnetic spectrum often by factors of 10 or more. The question
    about the relative effects of anthropogenic greenhouse gases and the
    Sun's radiation in terms of radiative forcing is certainly of interest
    but it does not add much to my current research quest to understand the
    Earth's mean climatic state and its nonlinear manifestations.

        Question 27. Please explain why you think the physically based
    climate models seem to quite satisfactorily represent the seasonal
    cycles of the climate at various latitudes based on the varying
    distributions of solar and infrared energy, but then would be so far
    off in calculating the climatic response for much smaller perturbations
    to solar radiation and greenhouse gases?
        Response. As indicated below, the first part of this sentence about
    a satisfactory representation of seasonal cycles of climate by computer
    climate models is not any assured statement of fact. This is why the
    followup question cannot be logically answered.
        For example, E. K. Schneider (2002, Journal of Climate, vol. 15,
    449-469) noted that:

            ``[a]t this writing, physically consistent and even flux-
            corrected coupled atmosphere-ocean general circulation models
            (CGCMs) have difficulty in producing a realistic simulation of
            the equatorial Pacific SST [sea surface temperature], including
            annual mean, annual cycle, and interannual variability. Not
            only do the CGCM simulations have significant errors, but also
            there is little agreement among models.''

    In a systematic comparison of the performance of 23 dynamical ocean-
    atmosphere models, Davey et al. (2002, Climate Dynamics, vol. 18, 403-
    420) found that ``no single model is consistent with the observed
    behavior in the tropical ocean regions . . . as the model biases are
    large and gross errors are readily apparent.'' Without flux adjustment,
    most models produced annual mean equatorial sea surface temperature in
    the central Pacific that are too cold by 2-3+ C. All GCMs except one
    simulated the wrong sign of the east-west SST gradient in the
    equatorial Atlantic. The GCMs also incorrectly simulated the seasonal
    climatology in all ocean sections and its interannual variability in
    the Pacific ocean.

        Question 28. In regard to your answers to the previous questions,
    to what extent is your indication of a larger climate sensitivity for
    solar than greenhouse gases due to quantitative analysis of the physics
    and to what extent due to your analysis of statistical correlations? Is
    this greater responsiveness for solar evident in the baseline climate
    system, or just for perturbations, and could you please explain?
        Response. Please see my answers to Questions No. 26 above and 30
    below.

        Question 29. Please explain why you seem to accept that solar
    variations, volcanic eruptions, land cover change, and perhaps other
    forcings can have a significant climatic influence, but changes in
    CO2 do not or cannot have a comparable influence?
        Response. Please see my answers to Question No. 30.

        Question 30. Could you please clarify why it is that you think the
    best way to get an indication of how much the climate will change due
    to global-scale changes in greenhouse gases or in solar radiation is to
    look at the regional level rather than the global scale? How would you
    propose to distinguish a natural variation from a climate change at the
    local to regional level?
        Response. Questions No. 28, 29 and 30 seem to be based on the
    unreasonable presumptions that some special insights about the effects
    of solar irradiation or land cover changes or even volcanic eruptions
    must be invoked or answered in order to challenge the role of carbon
    dioxide forcing in the climate system. That presumption is illogical.
    My basic view and research interest about carbon dioxide and the
    ongoing search for the right tool for modeling aspects of the Earth's
    climate system can be briefly summarized by my answers to Questions No.
    19, 25, 26, 27 and perhaps 20.
        As to your specific question on distinguishing a natural variation
    (either internally generated or externally introduced by solar
    variation or volcanic eruption) from a climate change by anthropogenic
    factors like land cover changes or carbon dioxide at the local to
    regional level, there is possibly a somewhat surprising answer. If one
    wish to single out the potential effects of man-made carbon dioxide
    against other natural and anthropogenic factors as hinted by your
    question, then the answer is clear--the CO2 effect is
    expected to be small in the sense that its potential signals will be
    likely be overwhelmed when compared with expected effects by other
    factors. It is a scientific fact that the signal of CO2 on
    the climate may be expected only over a very long time baseline and
    over a rather large areal extent. For example, Zhao and Dirmeyer (2003,
    COLA Technical Report No. 150; available at http://grads.iges.org/pubs/
    tech.html), in their modeling experiments that attempt to account for
    the realistic effects of land cover changes, sea surface temperature
    changes and for the role of added atmospheric CO2, found
    that

            ``[w]hen observed CO2 concentrations are specified
            in the model across the 18-year period, . . . we do not find a
            substantially larger warming trend than in CTL [with no change
            in CO2 concentration], although some small increase
            is found. The weak impact of atmospheric CO2 changes
            may be due to the small changes in specified CO2
            during the model simulation compared to the doubling CO2
            simulation, or the short length of the integrations. It is
            clear that the relatively strong SST [sea surface temperature]
            influence in this climate model is the driver of the [observed]
            warming.''

    Please also consider the point made by Lindzen (2002) under Question
    No. 8 above concerning the difficulties in linking the observed warming
    trend of the deep ocean (without challenging the quality and error of
    those deep ocean temperature data) to anthropogenic CO2
    forcing. Finally, I wish to note that Mickley et al. (2004, Journal of
    Geophysical Research, vol. 109, D05106) managed to use climate model
    simulations results to demonstrate ``the limitations in the use of
    radiative forcing as a measure of relative importance of greenhouse
    gases to climate change. . . . While on a global scale CO2
    appears to be a more effective `global warmer' than tropospheric ozone
    per unit forcing, regional sensitivities to increase ozone may lead to
    strong climate responses on a regional scale.''

        Question 31. How does your recent article relate to your
    assignments at the Harvard Smithsonian Observatory? Is paleoclimate
    part of the task of this observatory?
        Response. The publications of Soon et al. (2003) or Soon et al.
    (2004) are possible because of research grants that I and my
    collaborators obtained through competitive proposals to several
    research funding sources. I am a trust-fund employee at the Harvard-
    Smithsonian Center for Astrophysics and the support of my position and
    research work here is mainly through my own research initiative and
    proposal application. The scientific learning about paleoclimatic
    reconstruction presented in Soon et al. (2003) is related to my
    research interest in the mechanisms of sun-climate relation, especially
    for relevant physical pathways and processes on multidecadal and
    centennial time scales. Additional fruit of my independent research and
    labor in the area of sun-climate physics, funded or unfunded, is
    exemplified by the March 2004 book ``The Maunder Minimum and The
    Variable Sun-Earth Connection'' (see http://www.wspc.com/books/physics/
    5199.html) by W. Soon and S. Yaskell (published by World Scientific
    Publishing Company). It might also be instructive to note that
    paleoclimate researchers have been speculating about long-term
    variability of the sun as the cause of centennial- to millennial-scale
    variability seen in their proxy records.

        Question 32. In your testimony, you said that ``climate change is
    part of nature.'' Please describe what you meant, since obviously,
    climate change have occurred due, in part, to changes in various
    forcings, such as solar, continental drift, atmospheric composition,
    asteroid impacts, etc. rather than being just completely random events.
    Could you provide estimates of how large you consider future forcings
    might be and how big the climate change they might cause could be?
        Response. In this occasion, I am referring to the fact that any
    change or variability in climate is most likely a rule, rather than the
    exception, of the climate system. But I was not speaking about or
    trying to imply the factors of change, either naturally produced or
    man-made. I apologize for any potential confusion. It is certainly
    reasonable to suggest that those climatic changes may arise from
    ``forcings'' but it would be unwise to rule out internally generated
    manifestations of climatic variables that could be purely stochastic in
    origin. I would strongly recommend the pedagogical discussion by
    Professor Carl Wunsch of MIT in Wunsch (1992, Oceanography, vol. 5, 99-
    106) and Wunsch (2004, ``Quantitative estimate of the Milankovitch-
    forced contribution to observed Quaternary climate change'', working
    manuscript downloadable from http://puddle.mit.edu/cwunsch/).
        I cannot speculate on future climate forcings and resultant
    climatic changes because I found no basis for doing so.

        Question 33. Please provide a comparable estimate, with some
    supporting examples from the past, of how big you think the decadal (or
    50-year if you prefer) change in the hemispheric/global climate could
    be due to natural variability? If you prefer to focus on the regional
    scale change, could you provide an indication of any expected change in
    the degree of regional variability about the hemispheric and global
    values, and what the mechanism for this might be?
        Response. This question seems a related question trying to get at a
    quantitative comparison of how large natural climate variability on
    regional or hemispheric scale can be under the shadow of expected
    future changes. Again, with no intention to devalue this interesting
    question, I do not have sufficient knowledge nor ability to venture
    such an estimate. In fact, I would go so far to say that if the
    estimates of variability for both the past and future are known within
    a reasonable range of uncertainties, then the actual scientific
    research program to address questions about the role of added carbon
    dioxide no longer require further funding or execution since we have
    obtained all the relevant answers. But you may have judged from my
    answers given throughout this Q&A that much remains to be quantified
    and understood and the hard scientific research must continue.

        Question 34. Please explain the scientific basis for your testimony
    that ``one should expect the CO2 greenhouse effect to work
    its way downward toward the surface.''
        Response. Co-answer to this question is given under Question No.
    35.

        Question 35. Do you believe that there is greater greenhouse
    trapping of energy in the troposphere than at the surface and that the
    atmosphere has a low heat capacity? If so, how big is this temperature
    difference?
        Response. It is broadly agreed and assumed that carbon dioxide,
    when released into the air, has a tendency to get mixed up quickly and
    so is distributed widely through out the whole column of the
    atmosphere. The air near the surface is already dense and moist, so
    addition of more carbon dioxide will introduce very little imbalance of
    radiation energy budget there. In contrast adding more carbon dioxide
    to the thinner and drier air of the troposphere will cause a chain of
    noticeable effects. First, the presence of more carbon dioxide in the
    uppermost part of the atmosphere will cause more infrared radiation to
    escape into space because there are more carbon dioxide molecules to
    channel this infrared radiation upward and outward unhindered. Part of
    that infrared radiation is also being emitted downward to the lower
    parts of the atmosphere and the surface where it is reabsorbed by
    carbon dioxide and the thicker air there. The layer of air at the lower
    and middle troposphere, being more in direct contact with this down-
    welling radiation, is expected to heat more than air near the surface.
    Thus, adding more carbon dioxide to the atmosphere should cause more
    warming of the air around the height of two to seven kilometers.
    (Please consider for example the discussion by Kaser et al. (2004)
    under Question No. 8 about the ineffectiveness of an added longwave
    radiation from a direct addition of atmospheric CO2 or
    atmospheric temperature change in explaining the modern retreat of
    glaciers at Kilimanjaro.) In other words, the clearest impact of the
    carbon dioxide greenhouse effect should manifest itself in the lower-
    and mid-troposphere rather than near the earth's surface. Here, I am
    mostly speaking on the basis of expectation from pure radiative forcing
    considerations.
        Such a qualitative description is not complete, even though that is
    roughly what was modeled in the most sophisticated general circulation
    models (see e.g., Chase et al., 2004, Climate Research, vol. 25, 185-
    190), because it misses the key roles of atmospheric convection and
    waves as well as all the important hydrologic processes (please see
    e.g., Neelin et al., 2003, Geophysical Research Letters, vol. 30 (no.
    24), 2275 and consider additional remarks about water vapor and
    atmospheric convection under Question No. 25 as well as discussion on
    climate forcing factors and climate response sensitivities under
    Question No. 20). Some theoretical proposals expect a warming of the
    surface relative to the low- and mid-troposphere because of nonlinear
    climate dynamics (Corti et al., 1999, Nature, 398, 799-802). That
    expectation is because of the differential surface response with the
    pattern of Cold Ocean and Warm Land (COWL) that becomes increasingly
    unimportant with distance away from the surface (rather than just the
    difference in heat capacity mentioned in your question) [see Soon et
    al., 2001 for additional discussion]. Nevertheless, no GCM has yet
    incorporated such an idea into an operationally robust simulation of
    the climate system response to greenhouse effects from added
    CO2. In the latest ``global warming'' work, Neelin et al.
    (2003), for example, still distinctly differentiate between mechanisms
    for tropical precipitation that are initiated through CO2
    warming of the troposphere and through El Nino warming rooted in
    oceanic surface temperature and subsurface thermocline dynamics.
    (Further note that their model experiments [see Figure 2b+2c and
    10b+10c of Chou and Neelin, 2004, ``Mechanisms of global warming
    impacts on regional tropical precipitation'' in preparation for Journal
    of Climate; available at http://www.atmos.ucla.edu/?csi/REF/] also
    clearly shown that the troposphere warmed significantly more than
    surface with the doubling of atmospheric CO2 as discussed by
    Chase et al. 2004 below.)
        But it is worth noticing that the current global observation shows
    that, at least over the 1979-2003 interval, the lower tropospheric
    temperatures are not warming as fast as the surface temperatures (see
    Christy et al. 2003, Journal of Atmospheric and Oceanic Technology,
    vol. 20, 613-629; for additional confidence on the results derived by
    the University of Alabama-Huntsville group, please see Christy and
    Norris, 2004, Geophysical Research Letters, vol. 31, L06211). This
    observed fact is in contradiction to the accelerated warming of the mid
    and upper troposphere relative to surface simulated in current models
    (Chase et al. 2004). Chase et al. (2004) arrives at the following
    conclusions, upon examining results from 4 climate models in both
    unforced scenarios and scenarios forced with increased atmospheric
    greenhouse gases and the direct aerosol effect\3\:
    ---------------------------------------------------------------------------
        \3\ Such a study should also be consistently challenged by the
    discussion under question No. 20 about the adequacy of studying
    responses from a combination of incomp;ete forcings--through my primary
    purpose here is to illustrate the theoretical expectation of CO2
    forcing deriving from state-of-the-art climate models.

               ``Model simulations of the period representative of
            the greenhouse-gas and aerosol forcing for 1979-2000 generally
            show a greatly accelerated and detectable warming at 500 mb
            relative to the surface (a 0.06+ C
            decade-1increase).
               Considering all possible simulated 22 yr trends
            under anthropogenic forcing, a strong surface warming was
            highly likely to be accompanied by accelerated warming at 500
            mb [i.e., 987 out of 1018 periods or 97 percent of the cases
            had a larger warming at 500 mb than at the surface] with no
            change in likelihood as forcings increased over time.
               In simulated periods where the surface warmed more
            quickly than 500 mb, there was never a case [emphasis added] in
            which the 500 mb temperature did not also warm at a large
            fraction of the surface warming. A 30 percent acceleration at
            the surface was the maximum simulated as compared with an
            observed acceleration factor of at least 400 percent the mid-
            troposphere trend.
               In cases where there was a strong surface warming
            and the surface warmed more quickly than at 500 mb in the
            forced experiments, there was never a case in which the 500 mb-
            level temperatures did not register a statistically significant
            (p< 0.1) trend (i.e., a trend detectable with a simple linear
            regression model). The minimum p value of approximately 0.08
            occurred in the single case in which the significance was not
            greater than 99 percent.
               It was more likely that surface warmed relative to
            the mid-troposphere under control simulations than under forced
            simulations.
               At no time, in any model realization, forced or
            unforced, did any model simulate the presently observed
            situation of a large and highly significant surface warming
            accompanied with no warming whatsoever aloft.'' (p. 189)

        Question 36. The grants that are described as supporting your
    analysis seem to have much more to do with the sun or unrelated pattern
    recognition that with climate history (Air Force Office of Scientific
    Research-Grant AF49620-02-1-0194; American Petroleum Institute-Grants
    01-0000-4579 and 2002-100413; NASA-Grant NAG-7635; and NOAA-Grant
    NA96GP0448). Could you please describe how much funding you received
    and used in support of this study, all of the sources and the duration
    of that funding, and the relevance of those grant topics to the
    article?
        Response. All sources of funding for my and my colleagues' research
    efforts that resulted in the publication of Soon and Baliunas (2003)
    and Soon et al. (2003) were openly acknowledged. In other words, all
    sources of funding were disclosed in the manuscripts when they were
    submitted for publication; all sources of funding were also disclosed
    to readers in the printed journal articles. I am not the principal
    investigator for some of the grants we received (e.g., the NOAA grant
    was awarded to Professor David Legates), so I am not in the privilege
    position to provide exact quantitative numbers. But throughout the
    2001-2003 research interval in which our work was carried out, the
    funding we received from the American Petroleum Institute was a small
    fraction of the funding we received from governmental research grants.
        The primary theme of my research interest is on physical mechanisms
    of the sun-climate relationship. This is why researching into the
    detailed patterns of local and regional climate variability as
    published in Soon et al. (2003) is directly relevant to that goal.
    Please also consider my research position listed under Question No. 31
    above.

        Question 37. Have you been hired by or employed by or received
    grants from organizations that have taken advocacy positions with
    respect to the Kyoto Protocol, the U.N. Framework Convention on Climate
    Change, or legislation before the U.S. Congress that would affect
    greenhouse gas emissions? If so, please identify those organizations.
        Response. I have not knowingly been hired by, nor employed by, nor
    received grants from any such organizations described in this question.

        Question 38. Please describe the peer review process that took
    place with respect to your nearly identical articles published both in
    Climate Research and in Energy and Environment, including the number of
    reviewers and the general content of the reviewers' suggested edits,
    criticisms or improvements.
        Response. The Climate Research paper (Soon and Baliunas, 2003,
    Climate Research, vol. 23, 89-110) was submitted for publication and
    went through a routine peer-review process and was eventually approved
    for publication. The main content of the review was to propose: (a)
    reorganizing of materials including elimination of discussions on ENSO
    and GCMs; (b) removing ``tone'' problems by eliminating criticisms of
    previous EOF and superposition analyses; (c) reducing quotes especially
    those by Hubert Horace Lamb to improve readability; and (d) reviewing
    changes in each region with same thoroughness. The July 3, 2003's email
    (as Attachment I below) from the director of Inter-Research, Otto
    Kinne, who publishes Climate Research is enclosed below to confirm that
    the review process was fairly rigorous and all parties involved had
    carried out their roles and duties in this time-honored system
    properly.
        The extended and more complete paper by Soon et al. (2003, Energy &
    Environment, vol. 14, 233-296) was submitted to Energy & Environment
    for consideration together with the accepted Climate Research
    manuscript. Energy & Environment's editorial decision was to send our
    manuscript for review, and after acceptance, include in its editorial
    in Energy & Environment, volume 14, issues 2&3, a footnote referring to
    the Climate Research paper.
        Finally, we wish to correct that the false impression introduced by
    Professor Mann both during the testimony and in public media that his
    attack on the papers by Soon and Baliunas (2003) and Soon et al.
    (2003), in a FORUM article in the American Geophysical Union Eos
    newspaper (Mann et al., 2003, Eos, vol. 84, 256-258), were either
    rigorously peer-reviewed or represented widespread view of the
    community. Contrary to Professor Mann's public statements, a FORUM
    article in Eos is said to be only stating ``a personal point of view''
    (http://www.agu.org/pubs/eos--guidelines.html#authors). Whatever peer-
    reviewing that was done did not include soliciting comments from the
    authors of the papers being criticized. We first learned of this FORUM
    article from the AGU's press release No. 03-19 ``Leading Climate
    Scientists Reaffirm View that Late 20th Century Warming Was Unusual and
    Resulted From Human Activity'' (http://www.agu.org/sci--soc/prrl/
    prrl0319.html). See Soon et al. (2003b, Eos, vol. 84 (44), 473-476) for
    our own response to the Mann et al. FORUM article.

                                   __________

      Statement of Professor Michael E. Mann, Department of Environmental
                        Services, University of Virginia

        My name is Michael Mann. I am a professor in the Department of
    Environmental Sciences at the University of Virginia. My research
    involves the use of climate models, the analysis of empirical climate
    data, and statistical methods for comparing observations and model
    predictions. One area of active current research of mine involves the
    analysis of climate ``proxy'' records (that is, natural archives of
    information which record past climate conditions by their biological,
    physical, or chemical nature). These data are used to reconstruct
    patterns of climate variability prior to the period of the past century
    or so during which widespread instrumental climate records are
    available. A primary focus of this research is deducing the long-term
    behavior of the climate system and the roles of various potential
    agents of climate change, both natural and human.
        I was a Lead Author of the ``Observed Climate Variability and
    Change'' chapter of the Intergovernmental Panel on Climate Change
    (IPCC) Third Scientific Assessment Report and a scientific contributor
    for several other chapters of the report. I am the current organizing
    committee chair for the National Academy of Sciences `Frontiers of
    Science' and have served as a committee member or advisor for other
    National Academy of Sciences panels related to climate change. I have
    served as editor for the `Journal of Climate' of the American
    Meteorological Society. I'm a member of the advisory panel for the
    National Oceanographic and Atmospheric Administrations' Climate Change
    Data and Detection Program, and a member of numerous other
    international and U.S. scientific working groups, panels and steering
    committees. I have co-authored more than 60 peer-reviewed articles and
    book chapters on diverse topics within the fields of climatology and
    paleoclimatology. Honors I have received include selection in 2002 as
    one of the 50 leading visionaries in Science and Technology by
    Scientific American magazine, the outstanding scientific publication
    award for 2000 from the National Oceanographic and Atmospheric
    Administration, and citation by the Institute for Scientific
    Information (ISI) for notable recognition of my peer-reviewed research
    by fellow scientists.
        In my testimony here today, I will explain: (1) How mainstream
    climate researchers have come to the conclusion that late-20th century
    warmth is unprecedented in a very long-term context, and that this
    warmth is likely related to the activity of human beings. (2) Why a
    pair of recent articles challenging these conclusions by astronomer
    Willie Soon and his co-authors are fundamentally unsound.

                      CLIMATE HISTORY AND ITS IMPLICATIONS

        Evidence from paleoclimatic sources overwhelmingly supports the
    conclusion that late-20th century hemispheric-scale warmth was
    unprecedented over at least the past millennium and probably the past
    two millennia or longer.
        Modeling and statistical studies indicate that such anomalous
    warmth cannot be explained by natural factors but, instead, requires
    significant anthropogenic (that is, `human') influences during the 20th
    century. Such a conclusion is the indisputable consensus of the
    community of scientists actively involved in the research of climate
    variability and its causes. This conclusion is embraced by the position
    statement on ``Climate Change and Greenhouse Gases'' of the American
    Geophysical Union (AGU) which states that there is a compelling basis
    for concern over future climate changes, including increases in global-
    mean surface temperatures, due to increased concentrations of
    greenhouse gases, primarily from fossil-fuel burning. This is also the
    conclusions of the 2001 report of the Intergovernmental Panel on
    Climate Change (IPCC), affirmed by a National Academy of Sciences
    report solicited by the Bush administration in 2001 which stated, ``The
    IPCC's conclusion that most of the observed warming of the last 50
    years is likely to have been due to the increase in greenhouse gas
    concentrations accurately reflects the current thinking of the
    scientific community on this issue.''

                      THE MAINSTREAM SCIENTIFIC VIEWPOINT

        Human beings have influenced modern climate through changes in
    greenhouse gas concentrations, the production of industrial aerosols,
    and altered patterns of land-use. By studying both the record of
    ancient climate variability and the factors that may have influenced
    it, we can establish how and why the climate system varied naturally,
    prior to any large-scale anthropogenic impacts. Large changes in
    climate certainly occurred in the distant past. If we look 60 million
    years back in time, Dinosaurs were roaming the polar regions of the
    earth, and the globe was almost certainly warmer than today. Carbon
    dioxide levels were probably about double their current level, and had
    slowly attained such high levels due to changes in the arrangements of
    the continents (`plate tectonics') which influence the outgassing of
    carbon dioxide from the solid earth and thus, atmospheric greenhouse
    gas concentrations. These changes occur on timescales of tens of
    millions of years. 10,000 years ago, large ice sheets existed over
    North America due to natural changes that occur in the earth's orbit on
    timescales of tens of thousands of years. Trying to study distant past
    climates for insights into modern natural climate variability is
    hampered by the fact that the basic external constraints on the system
    (the continental arrangement, the geometry of the earth's astronomical
    orbit, the presence of continental ice sheets--what we call the
    `boundary conditions') were significantly different from today.
    Focusing on the evolution of climate in the centuries leading up to the
    20th century provides a perspective on the natural variability of the
    climate prior to the period during which large-scale human influence is
    likely to have occurred, yet modern enough that the basic boundary
    conditions on the climate system were otherwise the same. This provides
    us, in essence, a `control' for diagnosing whether or not recent
    climate changes are indeed unusual.
        Instrumental data for use in computing global mean surface
    temperatures are only available for about the past 150 years. Estimates
    of surface temperature changes prior to the 20th century must make use
    of historical documents and natural archives or ``proxy'' indicators,
    such as tree rings, corals, ice cores and lake sediments, to
    reconstruct the patterns of past climate change. Due to the paucity of
    data in the Southern Hemisphere, recent studies have emphasized the
    reconstruction of Northern Hemisphere rather than global mean
    temperatures. A number of independent reconstructions of the average
    temperature of the Northern Hemisphere support the conclusion that the
    hemispheric warmth of the late 20th century (i.e., the past few
    decades) is likely unprecedented over at least the past millennium.
    Preliminary evidence suggests that such a conclusion may well hold for
    at least the past two millennia, though more work, requiring the
    development of a more complete set of reliable proxy records spanning
    the past few millennia, are necessary to further decrease the
    uncertainties. Climate model simulations employing estimates of natural
    and anthropogenic radiative forcing changes agree well with the proxy-
    based reconstructions (Figure 1). The simulations, moreover, show that
    it is not possible to explain the anomalous late 20th century warmth
    without the contribution from anthropogenic influences. Such consensus
    findings are expressed in the recently published article co-authored by
    myself and 12 other leading climate scientists from the United States
    and Britain that appeared recently in the journal `Eos', the official
    transactions of the American Geophysical Union, the largest
    professional society in the field.

           FLAWS IN A RECENT STUDY DISPUTING THE SCIENTIFIC CONCENSUS

        Two deeply flawed (and nearly identical) recent papers by
    astronomers Soon and Baliunas (one of them with some additional co-
    authors--both henceforth referred to as `SB') have been used to
    challenge the scientific consensus. I outline the 3 most basic problems
    with their papers here:

    [GRAPHIC] [TIFF OMITTED] T2381.097

        (1) In drawing conclusions regarding past regional temperature
    changes from proxy records, it is essential to assess to make sure that
    the proxy data are indicators of temperature and not precipitation or
    drought. SB make this fundamental error when they cite evidence of
    either `warm', `wet', or `dry' regional conditions as being in support
    of an exceptional `Medieval Warm Period' or `MWP'. Their criterion, ad
    absurdum, could be used to define any period of climate as `warm' or
    `cold'. Experienced paleoclimate researchers know that they must first
    establish the existence of a temperature signal in a proxy record
    before using it to evaluate past temperature changes (Figure A1).
        (2) It is essential to distinguish between regional temperature
    changes and truly hemispheric or global changes. SB do not make this
    essential distinction. The wavelike character of weather (i.e., the
    day-to-day wiggles of the Jet Stream) ensures that certain regions tend
    to warm when other regions cool. This past winter is a case in point.
    January was about 2+ C below normal on the east coast of the U.S., but
    about 4+ C above normal over much of the west. Utah, Nevada and parts
    of California and Alaska had the warmest January on record (the change
    in location of the Iditarod dog sled race was a casualty of the Alaskan
    winter warmth!). The average temperature over the entire U.S. was about
    1+ C above normal, much less warm than for the western U.S., and of the
    opposite sign of the eastern U.S.
        In a similar manner, average global or hemispheric temperature
    variations on longer timescales tend to be much smaller in magnitude
    than those for particular regions, due to the tendency for a
    cancellation of warm and cold conditions in different regions. While
    relative warmth during the 10th-12th centuries, and cool conditions
    during the 15th-early 20th centuries are evident from reconstructions
    and model simulations of the average temperature of the Northern
    Hemisphere (Figure 1), the specific periods of cold and warmth
    naturally differ from region to region (Figure A2). The notion of an
    unusually cold 17th century `Little Ice Age', for example, arose in a
    European historical context. What makes the late 20th century unique is
    the simultaneous warmth indicated by nearly all long-term records
    (Figure A2), leading to the anomalous warmth evident during this period
    in Northern Hemisphere average temperatures (Figure 1).
        (3) It is essential, in forming a climate reconstruction, to
    carefully define a base period for modern conditions against which past
    conditions may be quantitatively compared. The concensus conclusion
    that late-20th century mean warmth likely exceeds that of any time
    during the past millennium for the Northern Hemisphere, is based on a
    careful comparison of temperatures during the most recent decades with
    reconstructions of past temperatures, taking into account the
    uncertainties in those reconstructions. As it is only the past few
    decades during which Northern Hemisphere temperatures have exceeded the
    bounds of natural variability, any analysis such as SB that compares
    past temperatures only to early or mid-20th century conditions, or
    interprets past temperatures using proxy information not capable of
    resolving decadal trends cannot address the issue of whether or not
    late-20th century warmth is anomalous in a long-term context.

                                  CONCLUSIONS

        The concentration of greenhouse gases in the atmosphere is higher
    than at any time in at least the last 400,000 years, and, it
    increasingly now appears, probably many millions of years. This
    increase is undeniably due to the activity of human beings through
    fossil fuel burning. Late 20th century warming is unprecedented in
    modern climate history at hemispheric scales. This is almost certainly
    a result of the dramatic increase in greenhouse gas concentrations due
    human activity. The latest model-based projections indicate a global
    mean temperature increase of 0.6 to 2.2+ C (1+ C to 4+ F) relative to
    1990 levels by the mid-20th century. While these estimates are
    uncertain, even the lower value would take us well beyond any previous
    levels of warmth seen over at least the past couple millennia. The
    magnitude of warmth, but perhaps more importantly, the unprecedented
    rate of this warming, is cause for concern.

    [GRAPHIC] [TIFF OMITTED] T2381.098

       Response by Michael Mann to Additional Questions by Senator Inhofe
        Question 1. You have used the term ``climate scientist'' to
    distinguish certain individuals. What, in your view, does it take for
    one to earn the title ``climate scientist''? What specific credentials,
    or the lack thereof, would lead you to refuse to recognize someone as a
    ``climates scientist''?
        Response. The term ``climate scientist'' is used, in my experience,
    to describe an individual with specific training in oceanographic,
    atmospheric, and coupled ocean-atmosphere processes relevant to
    understanding climate variability and the behavior of the climate
    system. An individual might obtain this training through either an
    advanced degree in those areas of study, or through years of research
    in those areas associated with numerous publications in the peer-
    reviewed climate literature such as ``Journal of Geophysical Research--
    Atmospheres'', ``Journal of Geophysical Research-Oceans'', ``Climate
    Dynamics'', ``The Holocene'', ``Geophysical Research Letters'',
    ``Paleoceanography'' (or publication of climate papers in leading
    international science journals such as ``Nature'' and ``Science''). I
    would not, for example, consider scientists with advanced degrees in
    Astronomy, Astrophysics, or Physics who have published primarily in
    those areas, as ``climate scientists''--nor do I believe would most of
    my colleagues in the climate research community. In addition to
    training and publishing in a field, leading scientists would normally
    be expected to be actively interacting and collaborating in studies
    with colleagues and ensuring their understanding of cutting edge
    science through attendance and active participation in meetings
    convened by the leading professional societies and organizations.

        Question 2. Your work and testimony contends that the Little Ice
    Age was not global, but restricted to only portions of Europe. A
    forthcoming article by Shindell et al. (Shindell, D.T. et al., 2003:
    Volcanic and solar forcing of climate change during the pre-industrial
    era. Journal of Climate, in press), however, indicates the Little Ice
    Age could have resulted from a combination of solar and volcanic
    forcing. Do you agree with these conclusions from Shindell et al.? If
    so, how can solar and volcanic forcings generate climatic effects that
    are not observed across the entire hemisphere?
        Response. The statement is incorrect. I never testified that the
    ``Little Ice Age was . . . restricted to only portions of Europe''.
        It should first be noted that many paleoclimatologists have
    questioned the utility of terms such as ``Little Ice Age'' and
    ``Medieval Warm Period'' which provide misleading descriptions of past
    climate changes in many regions. There is a complex pattern of climate
    variability in past centuries, and the lack of evidence for synchronous
    temperature variations worldwide in past centuries [e.g. Bradley, R.S.,
    and P.D. Jones, ``Little Ice Age'' summer temperature variations: their
    nature and relevance to recent global warming trends, The Holocene, 3,
    367-376, 1993; Hughes, M.K., and H.F. Diaz, Was there a `medieval warm
    period', and if so, where and when, Climatic Change, 26, 109-142,
    1994]. The cited paper by Shindell et al (2003), of which I am a co-
    author, is fully consistent with such findings. The paper, rather than
    demonstrating globally uniform patterns of warming or cooling in past
    centuries, shows that surface temperature changes were dominated by
    regional overprints associated with the response of the ``North
    Atlantic Oscillation'' atmospheric circulation pattern to radiative
    forcing. This response leads to a pattern of cooling during the 17th/
    18th centuries in certain regions (not just Europe, but many regions
    throughout the Northern Hemisphere extratropics) and warming in other
    regions. The paper shows that this pattern of warming and cooling
    closely resembles the pattern of surface temperature change during that
    interval reconstructed by Mann and colleagues (MBH98). It is worth
    noting, moreover, that the tropical Pacific seems to have been in a
    warmer, rather than a ``colder'' state, during the conventionally
    defined ``Little Ice Age'' [Cobb, K.M., Charles, C.D., Edwards, R.L.,
    Cheng, H., & Kastner, M. El Nino-Southern Oscillation and tropical
    Pacific climate during the last millennium, Nature 424, 271-276 (2003).
    Climate dynamists understand the importance of such phenomena in
    understanding the highly variable pattern of surface temperature
    changes in past centuries, and rarely, if ever, argue for the existence
    of globally uniform or synchronous temperature change in past
    centuries. The response of the climate to solar and volcanic radiative
    forcing is known to involves dynamical responses associated with
    regionally differentiated temperature trends that overprint far smaller
    global mean responses. This contrasts strongly with the response of the
    climate to anthropogenic climate forcing, for which the integrated
    global mean radiative forcing is considerably greater, and the
    associated large-scale warming typically rises above the regional
    variability.

        Question 3. That same paper finds ``long-term regional response to
    solar forcing [that] greatly exceeds unforced variability . . . and
    produces climateanomalies similar to those seen during the Little Ice
    Age. Thus, longterm regional changes during the pre-industrial [era]
    appear to havebeen dominated by solar forcing.'' You further state that
    ``For the few centuries prior to the industrial era, however,
    externally driven climate change is thought to have been forced
    primarily by only two factors: variation in solar output and volcanic
    eruptions . . . These forcings likely played a large role in the so-
    called Medieval Warm Period (MWP) and Little Ice Age (LIA) epochs of
    the last millennium, which saw significant climate changes on at least
    regional scales . . .'' You then define ``regional'' ``to mean
    continental in scale . . .'' Do you claim that total solar irradiance
    change is the only solar forcing mechanism that has any significant
    climate effect? List your formal training in, plus courses you have
    taught, in solar physics. Do you agree with the paper's claim that the
    MWP and LIA exist on regional scales, in accordance with climate
    experts like R. Bryson and H.H. Lamb, starting with their work in the
    1960's, and recently updated in summary in Soon et al. (2003)?
        Response. Expertise in ``solar physics'' is not the expertise
    required to evaluate what is happening to the Earth's climate--what
    matters are the changes in solar radiation at the top of the atmosphere
    and then down through it. As is made clear in our paper, we are
    considering not only ``total solar irradiance'' but also its spectral
    distribution. Indeed, because much of the change in solar radiation
    occurs in UV wavelengths, induced changes in stratospheric ozone can be
    lead to significant changes in atmospheric circulation in the
    troposphere. The model simulations indicate that such atmospheric
    circulation changes can, acting with other factors, lead to regional
    variations in the climate such as were observed over the last
    millennium. As a co-author of this paper, I of course, agree with its
    findings. However, the inference that this paper confirms the work of
    Soon et al. (2003) is very mistaken.
        With respect to my training, teaching, I would encourage that my
    Curriculum Vitae, which I have provided separately, be included in the
    record to be compared to those of the other witnesses with respect to
    relevant expertise and standing in the climate research community.

        Question 4. In your testimony, you stated that you hold the
    ``mainstream'' view with respect to climate theory of air temperature
    trends over the past two millennia. Provide supporting citations in the
    refereed scientific literature that are not authored or co-authored by
    you or your colleagues, collaborators, students or former students, or
    associates (i.e., Phil Jones, Ray Bradley, Malcolm Hughes), where
    others hold this Emainstream\1\ view.
        Response. The statement once again mischaracterizes my comments. As
    there is only one reconstruction of Northern Hemisphere annual mean
    temperature over the past two millennia, published only recently by
    Phil Jones and myself, it is hardly meaningful to discuss whether
    ``other studies'' support this finding. The peer-review and publication
    process typically unfolds on timescales of a year or longer, not
    months. Any careful reading of my comments would reveal that I was not
    referring to this one specific reconstruction in the comments I made
    characterizing what I believe to be the mainstream viewpoint of the
    climate research community. This review, as discussed in my testimony,
    refers rather to the widespread evidence that late 20th century warmth
    is unprecedented in a long-term context, anywhere from the past several
    centuries to nearly the past two millennia, depending on the timeframe
    of the particular study.
        Second, the description of ``collaborators, associates, former
    students'', depending on how interpreted, is so broad a category as to
    include just about every leading scientist in the field. The following
    publications all come to the same conclusion that late 20th century
    Northern Hemisphere warmth is anomalous in a long-term context:
         Bauer, E., Claussen, M., Brovkin, V., Assessing climate
    forcings of the earth system for the past millennium, Geophys. Res.
    Lett., 30 (6), 1276, doi: 10.1029/2002GL016639, 2003.
         Bertrand C., Loutre M.F., Crucifix M., Berger A., Climate
    of the Last millennium: a sensitivity study. Tellus, 54(A), 221-244,
    2002.
         Bradley, R.S., and P.D. Jones, ``Little Ice Age'' summer
    temperature variations: their nature and relevance to recent global
    warming trends, The Holocene, 3 (4), 367-376, 1993.
         Bradley, R.S., Briffa, K.R., Crowley, T.J., Hughes, M.K.,
    Jones, P.D, Mann, M.E., Scope of Medieval Warming, Science, 292, 2011-
    2012, 2001.
         Bradley, R.S., M.K.Hughes and H.F. Diaz., Climate in
    Medieval Time. Science, 302, 404-405, 2003.
         Pollack, H.N., S. Huang, and P.-Y. Shen, Climate Change
    Record in Subsurface Temperatures: A Global Perspective, Science, 282,
    279-281, 1998.

         Briffa, K.R., T.J. Osborn, F.H. Schweingruber, I.C.
    Harris, P.D. Jones, S.G. Shiyatov, S.G. and E.A. Vaganov, Low-frequency
    temperature variations from a northern tree-ring density network. J.
    Geophys. Res., 106, 2929-2941, 2001.
         Crowley, T.J., Causes of Climate Change Over the Past 1000
    Years, Science, 289, 270-277, 2000.
         Crowley, T.J., and T. Lowery, How Warm Was the Medieval
    Warm Period, Ambio, 29, 51-54, 2000.
         Gerber, S., F. Joos, P. Brugger, T. F. Stocker, M. E.
    Mann, S. Sitch, and M. Scholze, Constraining temperature variations
    over the last millennium by comparing simulated and observed
    atmospheric CO2, Climate Dynamics, 20, 281-299, 2003.
         Hegerl, G.C., T.J. Crowley, S.K. Baum, K-Y. Kim, and W. T.
    Hyde, Detection of volcanic, solar and greenhouse gas signals in paleo-
    reconstructions of Northern Hemispheric temperature. Geophys. Res.
    Lett., 30 (5), doi: 10.1029/2002GL016635, 2003.
         Huang, S., H. N.Pollack and P.-Y. Shen, Temperature Trends
    Over the Past Five Centuries Reconstructed from Borehole Temperature,
    Nature 403, 756-758, 2000.
         Jones, P.D., M. New, D.E. Parker, S. Martin, and I.G.
    Rigor, 1999: Surface air temperature and its changes over the past 150
    years. Reviews of Geophysics 37, 173-199.
         Jones, P.D., T.J. Osborn, and K.B. Briffa, The Evolution
    of Climate Over the Last Millennium, Science, 292, 662-667, 2001.
         Overpeck, J., K. Hughen, D. Hardy, R. Bradley, R. Case, M.
    Douglas, B. Finney, K. Gajewski, G. Jacoby, A. Jennings, S. Lamoureux,
    A. Lasca, G.M.J. Moore, M. Retelle, S. Smith, A. Wolfe, and G.
    Zielinski, Arctic Environmental Change of the Last Four Centuries,
    Science, 278, 1251-1256, 1997.
         Pollack, H.N., S. Huang, and P.-Y. Shen, Climate Change
    Record in Subsurface Temperatures: A Global Perspective, Science, 282,
    279-281, 1998.

        Question 5. Your work has been characterized as ``global'' in
    several venues, including the National Assessment. Is that a fair
    characterization, or are those sources confused by your use of Northern
    and Southern Hemisphere proxies in your Northern Hemisphere
    reconstruction? Can you explain why the National Assessment did not
    include error bars on your temperature reconstruction?
        Response. The proxy records on which our work is based represent
    conditions over much of the Northern Hemisphere and a small fraction of
    the Southern Hemisphere. While in any given year there can be some
    difference in the anomalies in the two hemispheres, the instrumental
    record indicates that over periods of a few decades or more, the
    anomalies in the two hemispheres are quite similar because of the
    thermodynamic and dynamic coupling between them. Thus, the major
    features of the temperature record, and in particular the unusual 20th
    century warming, are similar in the two hemispheres and thus global
    features. It was this aspect of the record to which the text of the
    National Assessment report refers in presenting the overall
    significance of our study, and the report is correct in suggesting that
    the 20th century warming is global in nature. The caption for Figure 2
    of Chapter 1 in the Foundation report (page 22 and page 544) states
    that ``Although this record comes mostly from the Northern Hemisphere,
    it is likely to be a good approximation to the global anomaly based on
    comparisons of recent patterns of temperature fluctuations.'' This
    accurately reflects the situation. In the Overview report (page 13),
    although the figure title says ``Global CO2 and Temperature
    Change,'' the caption next to the figure says ``Records of Northern
    Hemisphere surface temperatures, CO2 concentrations, and
    carbon emissions show a close correlation. Temperature change:
    reconstruction of annual-average Northern Hemisphere surface air
    temperatures derived from historical records, tree rings, and corals
    (blue), and air temperatures directly measured (purple).'' This quite
    clearly makes the point this is mainly a Northern Hemisphere
    temperature record.
        With respect to the question about the presentation of the figure,
    it is misleading to imply that the term ``error bars'' indicates that
    the central line is off by this amount--rather the limits mean that
    there is only 1 chance in 20 that the actual value is outside this
    range. That is, what we are showing is the likely range within which
    the anomaly lies, with there being a 95 percent chance the value is
    within this range. The line that we present in many of our figures, and
    that was presented in the National Assessment report, is the most
    likely value within this range (rather a natural choice to display in
    explaining a complex issue to the public). In looking at the National
    Assessment report, the caption for Figure 2 of Chapter 1 in the
    Foundation report (page 22 and page 544) states that ``The error bars
    for the estimate of the annual-average anomaly increase somewhat going
    back in time, with one standard deviation being about 0.25+ F (0.15+
    C).'' Quite clearly, the reader interested in investigating the
    accuracy of the records would followup by reading the original
    reference, which is cited in the text.
        In that I was not involved in the National Assessment report, the
    questioner should consult the authors of that report for any further
    information or questions.

        Question 6. You testified that the late 20th century warming is
    likely caused byman-made CO2 forcing on climate; what is
    your scientific proof for thatclaim Please detail how you removed the
    potential effects from other factors including those of sulfate
    aerosols, tropospheric and stratospheric ozone, volcanic dust veiling,
    black soot, solar particleand wave length-dependent variability, sea
    ice, land use, vegetation andother greenhouse gases?
        Response. The question inconsistently equates my statement of a
    ``likely'' causal relationship with the standard of ``scientific
    proof''. Scientists do not speak in terms of ``proof''. We speak in
    terms of likelihoods and the strength of evidence in support of a
    particular hypothesis.
        A large number of peer-reviewed scientific studies have been
    published in the leading scientific journals such as Nature and Science
    in the past two decades elucidating the role of natural and
    anthropogenic factors in observed climate changes. Physically based
    models have been developed and validated against observations, and
    these models reproduce complex climate phenomena such as El Nino. These
    same models have been driven with the primary ``external'' factors that
    are believed to govern climate variations on timescales of decades and
    centuries. These external factors include natural factors, such as the
    modest estimated variations in radiative output of the Sun, which
    varies by a fraction of a percent over time, variations in the
    frequency and intensity of explosive volcanic eruptions, which have a
    several-year cooling effect on the climate through the injection of
    reflective volcanic aerosols into the stratosphere, and very small
    changes in the Earth's orbit relative to the Sun that occur on multi-
    century timescales. These external factors also include the
    ``anthropogenic'' influences of increased greenhouse gas concentrations
    due to fossil fuel burning, changes in the reflective properties of the
    land surface due to human land use alterations, and the regional
    cooling effect of anthropogenic sulphate aerosols in certain industrial
    regions. When driven with these factors, these climate models have
    demonstrated a striking ability to reproduce observed global and
    hemispheric temperature trends during the 20th century, as well as
    longer-term trends in past centuries as reconstructed from proxy data.
    Such results have been demonstrated in the following peer-reviewed
    scientific articles:
         Wigley, T.M.L., R.L. Smith, and B.D. Santer, Anthropogenic
    Influence on the Autocorrelation Structure of Hemisoheric-Mean
    Temperatures, Science, 282, 1676-1680, 1998.
         Tett, S.F.B., P.A. Scott, M.R. Allen, W.J. Ingram, and
    J.F.B. Mitchell, Causes of Twentieth-Century Temperature Change Near
    the Earth's Surface, Nature, 399, 569-572, 1999.
         Hegerl, G.C., P.A. Scott, M.R. Allen, J.F.B. Mitchell,
    S.F.B. Tett, and U. Cubasch, Optimal detection and aftribution of
    climate change: sensitivity of results to climate model differences,
    Climate Dynamics, 16, 737-754, 2000.
         Crowley, T.J., Causes of Climate Change Over the Past 1000
    Years, Science, 289, 270-277, 2000.
         Stott, P.A., S.F.B. Tett, G.S. Jones, M.R. Allen, J.F.B.
    Mitchell, and G.J. Jenkins, External Control of 20th Century
    Temperature by Natural and Anthropogenic Forcings, Science, 290, 2133-
    2137, 2001.
         Stott, P.A., S.F.B. Tett, G.S. Jones, M.R. Allen, W.J.
    Ingram, and J.F.B. Mitchell, Attribution of twentieth century
    temperature change to natural and anthropogenic causes, Climate
    Dynamics, 17, 11-21, 2001.
        These conclusions, furthermore, were endorsed by the 2001 IPCC
    scientific working group report (Chapter 12), and the followup National
    Academy of Sciences report that endorsed most of the key IPCC
    conclusions.

        Question 7. A number of expert studies have produced individual
    proxy records that show the existence of a local Medieval Warm Period
    or Little Ice Age. Such studies cover a large portion of the globe. How
    do you reconcile your hemispheric reconstruction with these individual
    proxy records?
        Response. It is unclear to me what precisely the questioner means
    by ``a number of expert studies'' or how he defines the ``existence''
    of a ``Medieval Warm Period'' or ``Little Ice Age''. As discussed in my
    response to question 2, the regionally and temporally variable nature
    of climate changes in past centuries makes such descriptors of past
    climate change naive and often useless as a characterization of past
    changes. A sampling of some of the longest, high-quality best term
    proxy temperature estimates over the globe was provided in Figure 2 of
    the article: Mann, M.E., Ammann, C.M., Bradley, R.S., Briffa, K.R.,
    Crowley, T.J., Hughes, M.K., Jones, P.D., Oppenheimer, M., Osborn,
    T.J., Overpeck, J. T., Rutherford, S., Trenberth, K.E., Wigley, T.M.L.,
    On Past Temperatures and Anomalous Late 20th Century Warmth, Eos, 84,
    256-258, 2003. This figure demonstrates the lack of evidence for any
    periods in earlier centuries that are comparable in terms of evidence
    for sychronous warmth to the late 20th century. This same conclusion
    was also demonstrated by the recent article in Science: Bradley, R.S.,
    M.K. Hughes and H.F. Diaz., Climate in Medieval Time. Science, 302,
    404-405, 2003.

        Question 8. Do you claim 22 proxies to be a sufficient sample of
    observations for reconstructing a Northern Hemisphere temperature? If
    not, why did you consider it sufficient for the 1400-1450 interval in
    your 1998 Nature paper? If you do, there are 29 proxies that continue
    to 1984 in the data base you used for your 1998 paper. Why then did you
    terminate your temperature reconstruction at 1980? What efforts have
    you made to extend the proxy re-constructions up to the present?
        Response. The question is wrongly premised. The Mann et al (1998)
    study made use of almost 100 proxy series over the interval AD 1400-
    1450. The question appears to confuse the number of proxy series that
    was used, with the number of statistical indicators that were used to
    represent these proxy data. For example, the 70 series that make up the
    North American International Tree Ring Data Base date back to 1400,
    were represented in terms of their leading patterns of variance through
    a procedure known as ``Principal Component Analysis''. These patterns
    represented, however, a much larger number of underlying data. Most of
    the proxy records used in that analysis ended by 1980, limiting the
    useful upper limit to the calibration period used. A more recent paper
    (in press) extends proxy-based hemispheric temperature reconstructions
    through the mid-1990's, demonstrating the ability of the reconstruction
    to capture the accelerated warming evident in the instrumental record
    since 1980.

        Question 9. What are the patterns of temperature change in all
    proxies after 1980?
        Response. It is unclear what is meant by the question. Every proxy
    series which extends past 1980 exhibits its own particular pattern. A
    recent paper (in press), as referred to in Question No. 8, demonstrates
    that a composite of proxy temperature indicators with reliable low-
    frequency variability that are available through the mid-1990's capture
    the accelerated warming after 1980.
        All of the data used in our study have been available since July
    2002 on the public ftp site: ftp://holocene.evsc.virginia.edu/pub/
    MBH98/.

        Question 10. Do you have any external (not derived by you) method
    or data to provide verification of your temperature reconstruction
    Please explain.
        Response. We used the method of cross-validation to independently
    demonstrate the statistical reliability of our reconstructions. This is
    detailed in MBH98 and MBH99. We did not derive the method of cross-
    validation--it is a well established statistical procedure, detailed in
    many introductory level statistics textbooks.

        Question 11. Are you aware of any errors in your data compilation
    for MBH98 or MBH99? If so, what are they?
        Response. We are not aware of any errors. We are, however, aware of
    recent spurious claims of such errors by the authors of an article
    published in the social science journal ``Energy and Environment''.
    These claims have already been widely discredited by a cursory analysis
    of the paper, and a manuscript detailing the numerous fundamental
    errors made in the Energy and Environment paper has been submitted to
    the peer-reviewed literature. We would be happy to provide a copy of
    the paper to be made part of the official Senate record once it is
    published.

        Question 12. Are you aware of any errors in any calculations that
    you made in MBH98 or MBH99? If so, what are the errors?
        Response. See response to question 11.

        Question 13. Vegetation grows as a result of a number of factors,
    including energy input, moisture supply, fire frequencies, and species
    competition. Do you claim it is possible to accurately remove the
    effects of these factors from your tree ring proxy datasets to produce
    a resulting time-series represents fluctuations in only air
    temperature? What is the magnitude of the error introduced in
    developing a procedure to remove these other effects? Please detail the
    analyses and list peer-reviewed works that specifically outline
    techniques to remove the effect of these other indicators for inferring
    past temperatures.
        Response. One of the co-authors of MBH98 (Malcolm Hughes) is among
    the world's foremost experts in dendroclimatology, so the team of MBH98
    hardly needs to be informed of the processes that influence tree
    growth. The method of MBH98 does not ``remove'' various factors from
    tree ring proxy information (which would be a most unwise approach!)
    but, rather, uses multivariate statistical methods similar to those
    commonly used in climate and paleoclimate field reconstruction [see
    e.g. Cook, E.R., K.R. Briffa, and P.D. Jones, Spatial Regression
    Methods in Dendroclimatology: A Review and Comparison of Two
    Techniques, International Journal of Climatology, 14, 379-402, 1994;
    Smith, T.M., R.W. Reynolds, R.E. Livezey, and D.C. Stokes,
    Reconstruction of Historical Sea Surface Temperatures Using Empirical
    Orthogonal Functions, Journal of Climate, 9, 1403-1420, 1996; Kaplan,
    A., Y. Kushnir, M.A. Cane, and M.B. Blumenthal, Reduced space optimal
    analysis for historical data sets: 136 years of Atlantic sea surface
    temperatures, Journal of Geophysical Research, 102, 27835-27860, 1997]
    to separate the information in the data that can meaningfully be
    related to surface temperature variations from that related to other
    influences.

        Question 14. Define the difference between variability and error in
    a statistical analysis. In EOF analyses, is the variation of the first
    principal component indicative of the uncertainty associated with the
    data? Why or why not?
        Response. Variability in an estimated quantity can be thought of as
    representing both `signal' (the physical quantity one is interested in
    and `noise' (everything else). The definition of noise and signal
    depends on a number of assumptions regarding the nature of the process
    that generated the times series of interest and the specification of
    the statistical model for the data in question. Uncertainty, which is
    associated with the partitioning of data variance into ``noise and
    signal'', as defined above, depends on such detailed considerations.
    There are no general statistical principles that I am familiar with
    that relate uncertainty, thusly defined, to the first, or any other,
    principal component of a dataset containing both signal and noise
    contributions. Uncertainty is typically diagnosed by the analysis of
    residual variance from a statistical model based on a combined
    calibration/cross-validation procedure. Introductory text books such as
    ``Statistical Methods in the Atmospheric Sciences'' (D. Wilks, Academic
    Press) deal with this topic in detail.

        Question 15. Specifically, how do you construct regional patterns
    of temperature changes in past centuries when data are limited, either
    spatially, temporally, or both?
        Response. Our methods are described in detail in the following
    peer-reviewed scientific publications, which I would like to have made
    part of the official Senate record:
         Mann, M.E., Jones, P.D., Global Surface Temperatures over
    the Past two Millennia, Geophysical Research Letters, 30 (15), 1820,
    10.1029/2003GL017814, 2003.
         D'Arrigo, R.D., Cook, E.R., Mann, M.E., Jacoby, G.C.,
    Tree-ring reconstructions of temperature and sea level pressure
    variability associated with the warm-season Arctic Oscillation since AD
    1650, Geophysical Research Letters, 30 (11), 1549, doi: 10.1029/
    2003GL017250, 2003.
         Mann, M.E., Rutherford, S., Bradley, R.S., Hughes, M.K.,
    Keimig, F.T., Optimal Surface Temperature Reconstructions Using
    Terrestrial Borehole Data, Journal of Geophysical Research, 108 (D7),
    4203, doi: 10.1029/2002JD002532, 2003.
         Rutherford, S., Mann, M.E., Delworth, T.L., Stouffer, R.,
    Climate Field Reconstruction Under Stationary and Nonstationary
    Forcing, Journal of Climate, 16, 462-479, 2003.
         Mann, M.E., Large-scale climate variability and
    connections with the Middle East in past centuries, Climatic Change,
    55, 287-314, 2002.
         Cook, E.R., D'Arrigo, R.D., Mann, M.E., A Well-Verified,
    Multi-Proxy Reconstruction of the Winter North Atlantic Oscillation
    Since AD 1400, Journal of Climate, 15, 1754-1764, 2002.
         Mann, M.E., Rutherford, S., Climate Reconstruction Using
    `Pseudoproxies', Geophysical Research Letters, 29 (10), 1501, doi:
    10.1029/2001GL014554, 2002.
         Mann, M.E., Large-scale Temperature Patterns in Past
    Centuries: Implications for North American Climate Change, Human and
    Ecological Risk Assessment, 7 1247-1254, 2001.
         Mann, M.E., Climate During the Past Millennium, Weather
    (invited contribution), 56, 91-101, 2001.
         Cullen, H., D'Arrigo, R., Cook, E., Mann, M.E.,
    Multiproxy-based reconstructions of the North Atlantic Oscillation over
    the past three centuries, Paleocean-
    ography, 15, 27-39, 2001.
         Mann, M.E., Gille, E., Bradley, R.S., Hughes, M.K.,
    Overpeck, J.T., Keimig, F.T., Gross, W., Global Temperature Patterns in
    Past Centuries: An interactive presentation, Earth Interactions, 4-4,
    1-29, 2000.
         Delworth, T.L., Mann, M.E., Observed and Simulated
    Multidecadal Variability in the Northern Hemisphere, Climate Dynamics
    16, 661-676, 2000.
         Mann, M.E., Bradley, R.S. and Hughes, M.K., Northern
    Hemisphere Temperatures During the Past Millennium: Inferences,
    Uncertainties, and Limitations, Geophysical Research Letters, 26, 759-
    762, 1999.
         Mann, M.E., Bradley, R.S., and Hughes, M.K., Global-Scale
    Temperature Patterns and Climate Forcing Over the Past Six Centuries,
    Nature, 392, 779-787, 1998.

        Question 16. Do you claim that the instrumental temperature record
    is known without error? If not, what error and uncertainty would you
    associate with the annual Northern Hemisphere averaged air temperature
    for 1900? For 1950? For 2000? How were these estimates incorporated
    into your analysis?
        Response. The claim made by Dr. Legates in his testimony that we
    present the instrumental record without uncertainty is incorrect. If
    Legates, for example, were familiar with studies of the instrumental
    surface temperature record, he would understand that the uncertainties
    in this record during the 20th century are small compared to the
    uncertainties shown for our reconstruction [see e.g. Figure 2.1b in
    Folland, C.K., Karl, T.R., Christy, J.R., Clarke, R. A., Gruza, G.V.,
    Jouzel, J., Mann, M.E., Oerlemans, J., Salinger, M.J., Wang, S.-W.,
    Observed Climate Variability and Change, in Climate Change 2001: The
    Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press,
    Cambridge, 99-181, 2001.]. Furthermore, all scientists with a proper
    training in statistics know that uncertainties add ``in quadrature''.
    In other words, you have to square them before adding them. This means
    that the relatively small uncertainty in the instrumental record makes
    a relatively small contribution to the total uncertainty. Legates
    claimed in his testimony that including the uncertainty in the
    instrumental record, which he estimates as 0.1oC would change the
    conclusions expressed by us and other mainstream climate scientists
    that the 1990's are the warmest decade in at least the past 1000 years
    within estimated uncertainties. This claim is very misleading for
    several reasons, First, the standard error in Northern Hemisphere mean
    annual temperatures during the 1990's is far smaller than the amount
    cited by Legates [see again Folland et al, 2001 cited above]. Even more
    problematic, however, Legates claim indicates a fundamental
    misunderstanding of the statistical concepts of standard error and
    uncertainty. The shaded region shown along with the Mann et al
    reconstruction (and other similar plots shown in recent articles such
    as the aforementioned ``Eos'' article, and the IPCC report) indicates
    two standard error intervals. The decade of the 1990's is roughly two
    standard errors warmer (i.e., about 0.4oC)] than any decade prior to
    the 20th century in the reconstruction. Based on a one-sided test for
    anomalous warmth, this translates to a roughly 97.5 percent level of
    significance. Modifying the uncertainties to include the small
    additional contribution due to uncertainties in the instrumental record
    itself would modify this only slightly, and would not lower the
    significance level below the 95 percent level. Though there is no such
    thing as an absolute estimate of uncertainty, despite Legate's
    implications to the contrary, a 95 percent confidence is often adopted
    as an appropriate criterion for significance. Legates' statement that
    including instrumental contributions to the uncertainty would change
    the conclusions is thus clearly false.

        Question 17. Assuming a proxy record extended back to 1000 A.D.,
    what specifically would be required to disqualify this proxy record
    from your analyses? Provide supporting evidence where others have
    disqualified such records from temperature analyses on these criteria.
        Response. It is unclear what type of ``analyses'' are being
    referred to here. I have used a variety of different statistical
    methods and data in various published studies describing paleoclimate
    reconstruction, so the question as worded is implicitly vague. In any
    case, our approaches do not ``disqualify'' proxy data. They use
    objective statistical criteria to evaluate the strength of the signal
    available for reconstruction of the particular climate field or index
    (be it related to surface temperature, atmospheric circulation,
    drought, or other variables) to be reconstructed. Such statistical
    approaches, and the related approaches used by other climate
    researchers, are described in the various publications listed above in
    the response to Questions No. 13 and 15.

        Question 18. Have you made available via FTP the coefficients
    developed to relate proxies to principal components? If not, would you
    make those coefficients available at NGDC/paleo?
        Response. The question is based on two false premises. The first
    involves a naive view of what is required and expected of scientific
    researchers. It is unprecedented in my experience for any scientist to
    post in the public domain every single computational aspect of a
    complicated analysis. The methods of our study were adequately
    described in our paper and supplementary information, and the data used
    were made available in the public domain. Indeed, we made far more of
    our results, data, and methodological details available in the public
    domain than is provided in most similar scientific studies. The
    scientific funding agencies (DOE, NSF, and NOAA) would have informed us
    if we had not followed the appropriate protocols in the provision of
    data and results.
        The second false premise is a technical one. A proper understanding
    of the methodology employed by MBH98 would reveal that there is no one
    fixed set of ``coefficients'' that relate a particular proxy record to
    a particular principal components. The relationship is determined based
    on time-dependent inverse problem for which the weights on different
    records are not fixed over time, as described in our published
    articles.

        Question 19. Have you made available via FTP any specialized
    computer studies, such as Matlab scripts, in connection with your
    temperature reconstruction? If not, would you make any such scripts
    used in developing the temperature reconstructions in MBH98 and MBH99
    available through NGDC/paleo?
        Response. The methodologies have been described, and other climate
    researchers have independently, successfully implemented the
    methodology, e.g.: Zorita, E., F. Gonzalez-Rouco, and S. Legutke,
    Testing the Mann et al. (1998) Approach to Paleoclimate Reconstructions
    in the Context in a 1000-Yr Control Simulation with the ECHO-G Coupled
    Climate Model, Journal of Climate, 16, 1378-1390, 2003.

        Question 20. Do you claim your method of reconstructing past
    temperature from proxies is the only correct one? If not, please submit
    some published papers that use methods you consider to be correct as
    well. If you do consider yours the only correct method, can you provide
    a list of names of scientists whom you have contacted to tell them they
    are using the wrong methods in their work?
        Response. The question is based on the false premise that my
    colleagues and I use any one particular ``method'' of reconstructing
    past temperatures from proxy data. In fact, I have published on the
    application of at least five fundamentally independent methods for
    using proxy data to reconstruct past climate patterns in the peer-
    reviewed literature. Examples of the applications of different methods
    can be found in the following peer-reviewed scientific publications:
         Zhang, Z., Mann, M.E., Cook, E.R., Alternative Methods of
    Proxy-Based Climate Field Reconstruction: Application to the
    Reconstruction of Summer Drought Over the Conterminous United States
    back to 1700 From Drought-Sensitive Tree Ring Data, Holocene, in press,
    2003.
         Mann, M.E., Jones, P.D., Global Surface Temperatures over
    the Past two Millennia, Geophysical Research Letters, 30 (15), 1820,
    10.1029/2003GL017814, 2003.
         Mann, M.E., Rutherford, S., Bradley, R.S., Hughes, M.K.,
    Keimig, F.T., Optimal Surface Temperature Reconstructions Using
    Terrestrial Borehole Data, Journal of Geophysical Research, 108 (D7),
    4203, doi: 10.1029/2002JD002532, 2003.
         D'Arrigo, R.D., Cook, E.R., Mann, M.E., Jacoby, G.C.,
    Tree-ring reconstructions of temperature and sea level pressure
    variability associated with the warm-season Arctic Oscillation since AD
    1650, Geophysical Research Letters, 30 (11), 1549, doi: 10.1029/
    2003GL017250, 2003.
         Mann, M.E., Bradley, R.S., and Hughes, M.K., Global-Scale
    Temperature Patterns and Climate Forcing Over the Past Six Centuries,
    Nature, 392, 779-787, 1998
        On occasion, there are approaches used that are not adequate. For
    example, the approach of simply counting papers and not properly
    defining what constitutes an anomaly, as was the case for the paper by
    Soon et al. (2003), is most decidedly not adequate. Also, the analysis
    approach used by McIntyre and McItrick (2003) in which the authors
    attempted to reproduce the results of the previous study of MBH98 based
    on an analysis which used neither the same data (the authors eliminated
    the majority of data used by MBH98 for the first two centuries of the
    reconstruction) , or method as the original authors, was woefully
    inadequate. In fact, this latter study was described as ``seriously
    flawed'' and ``silly'' in a recent article in USA Today (``Global
    Warming Debate Heats Up Capitol Hill'', 11/19/03). When deeply flawed
    studies such as this are published, I am interested in determining what
    errors have been made and, if necessary as in this latter case,
    promptly submitting a rebuttal to the peer-reviewed scientific
    literature to ensure that the scientific community is not misled by the
    use of inadequate approaches. To my knowledge, I am not considered to
    be shy in offering criticism where criticism is due.

        Question 21. If there are other acceptable methods, did you try any
    of them on your data set prior to its publication to see what the
    results would be? If so would you please submit the results. If not,
    have you done so since? Why do you claim your multi-proxy results
    represent a ``robust consensus,'' as you said in your Eos publication,
    if you have not verified that its results would also be obtained using
    other acceptable methods?
        Response. As demonstrated both in the Eos article, and the various
    references provided in my response to Question 4, about a dozen
    different recent estimates based on a variety of data and approaches,
    published by different groups, yield statistically indistinguishable
    histories of Northern Hemisphere mean temperature changes in past
    centuries. I define such a result as characterizing a ``consensus''.

        Question 22. Did you at any time prior to publication compute the
    analysis up to 1984 or later? What were the results? If you did not,
    even though you had sufficient data, why not? If you did but you did
    not use those results, explain why. If the results were different,
    where did you publish a discussion of those differences? If they were
    the same, why did you delete them? Why, in other words, did you throw
    out data for the period of maximum interest?
        Response. Most of the proxy records used in MBH98 and MBH99 ended
    by 1980, limiting the useful upper limit to the calibration period
    used. A more recent paper (in press) extends proxy-based hemispheric
    temperature reconstructions through the mid-1990's, demonstrating the
    ability of the reconstruction to capture the accelerated warming
    evident in the instrumental record since 1980. We would be happy to
    provide a copy of this paper to be made part of the official Senate
    record when it is formally published.

        Question 23. On your web site http://www.ngdc.noaa.gov/paleo/ei/
    data--supp.html where you explain the assembling of the data base for
    your 1980 paper you say: ``Small gaps have been interpolated. If
    records terminates lightly before the end of the 1902-1980 training
    interval, they are extended by persistence to 1980.'' Does this mean
    you made up some observations to fill in blank spots in the data
    records? Have you ever provided a complete public listing of all the
    data you made up? Please provide such a listing now. Of the 112
    proxies, in how many of them did you fill gaps? Why in some of them but
    not others? What is the longest interval of time over which you filled
    in missing observations?
        Response. Extension of missing values by `persistence' of the final
    available value is a typical statistical approach to estimating small
    amounts of unavailable data at the end of a time series (see e.g. the
    textbook by Wilks, referred to in the response to Question No. 14). The
    fact that this approach was used to infill a modest number of missing
    observations between 1972 and 1980 was described in the Nature
    supplementary information. All of the data used in our study have been
    available since July 2002 on the public ftp site: ftp://
    holocene.evsc.virginia.edu/pub/MBH98/.

        Question 24. What was the effect on your results of filling in the
    missing data? Did you run your analysis without it? Please submit the
    results when the filled-in data are dropped from the analysis. If it
    changes your results, where is that discussed If it makes no
    difference, why did you do it?
        Response. The use of infilled data has essentially no effect on the
    reconstruction, as demonstrated by the fact that the same result is
    achieved if a 1902-1971 calibration period (which predates the use of
    any infilled proxy data) is used instead of a 1902-1980 calibration
    period. It is advisable to use the full 1902-1980 calibration interval,
    however, because the increased statistical constraint provided by the
    lengthening of the calibration period more than offsets the impact of
    the use of a modest amount of in-filled data in a small number of
    series.

        Question 25.  Do you agree that statistical methods based on linear
    extrapolation from data representing the far extreme of the line are
    associated with an added error/uncertainty? If so, how was this
    incorporated into the assessment of the error/uncertainty in your
    temperature reconstructions? Please provide citations from your
    publications. If not, please explain why the uncertainty envelope of a
    linear regression grows larger as a function of the distance from the
    mean of the data used to fit the parameters and why this was not
    included in your research.
        Response. The so-called ``leverage effect'' which the question
    appears to refer to, is taken into account through consideration of the
    spectrum of the calibration residuals, allowing for resolution of any
    enhancement of uncertainty as a function of frequency (see MBH99).
    Alternatively, the uncertainties can be evaluated from an independent
    sample (i.e., cross-validation, rather than calibration, residuals)
    that eliminates any influence of calibration period leverage in the
    estimation of uncertainties. Both approaches give similar results [e.g.
    Rutherford, S., Mann, M.E., Osborn, T.J., Bradley, R.S., Briffa, K.R.,
    Hughes, M.K., Jones, P.D., Proxy-based Northern Hemisphere Surface
    Temperature Reconstructions: Sensitivity to Methodology, Predictor
    Network, Target Season and Target Domain, Journal of Climate,
    submitted, 2003].

        Question 26. Please describe the peer review process that took
    place with respect to your Forum article that appeared in EOS on July
    8, 2003. If, according to the AGU, the EOS Forum contains articles
    stating a personal point of view on a topic related to geophysical
    research or the relationship of the geophysical sciences to society,
    how can you claim that your article is peer reviewed?
        Response. The article was independently reviewed and evaluated for
    suitability for publication by an editor who has expertise in the
    particular subject area. The associated process is correctly described
    as ``peer review''. Appropriate to the relatively short and non-
    technical nature of Eos ``Forum'' pieces, the associated peer review
    process is not as extensive as that employed for articles in the more
    technical literature such as Geophysical Research Letters, or Journal
    of Geophysical Research. I would suggest that the questioner contact
    representatives at AGU for more details on the peer-review process
    employed for their different journals and paper categories.

        Question 27. Do you claim that producing estimates of past climate
    states is an exact science If so, explain why different authors can get
    such significantly different results when investigating and
    reconstructing past temperature, and detail the errors that other
    authors must have made. If not, explain how there can be, as you put it
    in your EOS article, a ``robust consensus'' regarding the correct
    estimate of the climate state of the past millennium.
        Response. The term ``exact science'' is generally not used, or
    considered meaningful or appropriate by scientists, as science almost
    always involves the testing of hypotheses based on the use of
    intrinsically uncertain data or observations. Consistent with this
    fundamental aspect of nearly all scientific endeavors, my colleagues
    and I, and other researchers in the paleoclimate community, typically
    interpret the results of paleoclimate reconstructions within the
    context of sometimes substantial associated uncertainties. When a large
    number of estimates agree with each other within estimated
    uncertainties, and those uncertainties are modest enough to still allow
    for non-trivial conclusions (for example, that late 20th century warmth
    is anomalous in a long-term context), those conclusions can be
    considered as both ``robust'' and a ``consensus''.

        Question 28. Please describe the peer review process that took
    place with respect to your 1999 Geophysical Research Letters paper.
    What were the criticisms or improvements suggested by the referees? Why
    was no reference made to the anomalous global warming caused by the
    very strong El Nino event of 1997-98 in your paper? Is this 1999 paper
    continuation of your 1998 paper in Nature where you stopped your
    reconstruction at AD 1400?
        Response. The comments of reviewers on a manuscript are considered
    a confidential matter, involving the editor, reviewers, and authors.
    Providing these comments for public record would be ethically
    questionable, and probably violates the confidentiality policies of the
    associated journals. Minor suggestions were made by the reviewers and
    editor, and addressed to their satisfaction prior to the acceptance and
    publication of the paper.

        Question 29.  In Mann and Jones 2003 Geophysical Research Letters,
    did you change your methodology in the reconstruction of the
    hemispheric or global scale temperature from your prior publications?
    If so, why did you, and what is the rationale for the change of
    approach?
        Response. The question is wrongly premised, as it presumes, through
    the use of the language ``change your methodology'' that scientists
    only have one particular methodological approach that can be applied to
    a problem at hand. As discussed in my answer to question 20, my
    research has involved the use of a variety of different methods for
    reconstructing past climate patterns from proxy data. The paper by Mann
    and Jones (2003), for example, uses a coarser resolution proxy dataset
    than MBH98/MBH99 and a compositing methodology that allows for the
    reconstruction of decadal, but not annual, changes, and the
    reconstruction of hemispheric mean, but not spatially resolved,
    patterns of temperature in past centuries. In doing so, the study was
    able to make use of a more restricted set of temperature records
    available over a longer timeframe than those used in previous high-
    resolution proxy reconstructions of hemispheric temperature change.

        Question 30. Did IPCC carry out any independent programs to verify
    the calculations that you made in MBH98 or MBH99? If so, please provide
    copies of the reports resulting from such studies.
        Response. It is distinctly against the mission of the IPCC to
    ``carry out independent programs'', so the premise of the question is
    false. However, the IPCC's author team did engage in a lively
    interchanges about the quality and overall consistency of all of the
    papers as the chapter was drafted and revised in the course of review.

        Question 31. Did IPCC carry out any independent quality control on
    the data that you used in MBH98 and MBH99? If so, please provide copies
    of the reports resulting from such studies.
        Response. The IPCC doesn't ``carry out studies'', so the premise of
    the question is false. The IPCC instead depends that the normal
    scientific peer-review process, especially when done in a leading
    journal, has ensured an acceptable level of quality. In addition, the
    IPCC does check to see if any criticisms have been raised postreview in
    comments and response to the journal articles.

        Question 32. Did IPCC carry out any studies to validate the
    statistical procedures and methodologies used in MBH98 and MBH99? If
    so, please provide copies of the reports resulting from such studies.
        Response. The IPCC doesn't ``carry out studies'', so the premise of
    the question is false. Instead, as indicated above, the IPCC relies on
    earlier stages of review to cover such matters.

        Question 33. Has any organization other than IPCC or your
    associates carried out any independent programs to verify the
    calculations that you made in MBH98 or MBH99? If so, please provide
    copies of the reports resulting from such studies.
        Response. I know of no ``organizations'' that carry out
    ``independent programs'' to verify calculations of individual co-
    authors. If the question is, have other scientists reproduced the basic
    results of MBH98 and MBH99, the answer is yes. Numerous other groups
    (see the dozen or so independent estimates of various groups shown in
    Figure 1 of: Mann, M.E., Ammann, C.M., Bradley, R.S., Briffa, K.R.,
    Crowley, T.J., Hughes, M.K., Jones, P.D., Oppenheimer, M., Osborn,
    T.J., Overpeck, J.T., Rutherford, S., Trenberth, K.E., Wigley, T.M.L.,
    On Past Temperatures and Anomalous Late 20th Century Warmth, Eos, 84,
    256-258, 2003) have produced reconstructions that are remarkably
    similar to those of MBH98 based on a variety of data and methods. Refer
    back to my answer to question 4 for further details. I would like to
    see each of these papers made an official part of the Senate record.

        Question 34. Has any organization other than IPCC conducted
    independent quality control on the data that you used in MBH98 and
    MBH99? If so, please provide copies of the reports resulting from such
    studies.
        Response. The IPCC doesn't ``carry out studies'', so the premise of
    the question is false. The data used by MBH98 (and MBH99) were produced
    by other researchers, not Mann and colleagues. It is thus not clear
    what kind of ``independent quality control'' is being referred to here.
    However, it is fair to say that each of these papers has been subject
    to rigorous peer review in a leading scientific journal, which is
    considered by scientists to be an independent quality control process.
    We are aware of no criticisms of the datasets in the peer-reviewed
    scientific literature.

        Question 35. Has any organization other than IPCC carried out any
    studies to validate the statistical procedures and methodologies used
    in MBH98 and MBH99? If so, please provide copies of the reports
    resulting from such studies.
        Response. The IPCC doesn't ``carry out studies'', so the premise of
    the question is false. If the question were asked: Have other
    independent groups tested the methodology of Mann et al (1998) in a
    publication in the peer-reviewed climate literature, the answer would
    be ``yes''. I would refer the questioner to the following paper:
    Zorita, E., F. Gonzalez-Rouco, and S. Legutke, Testing the Mann et al.
    (1998) Approach to Paleoclimate Reconstructions in the Context in a
    1000-Yr Control Simulation with the ECHO-G Coupled Climate Model,
    Journal of Climate, 16, 1378-1390, 2003.
        The paper arrives at the conclusion that the methodology of MBH98
    performs well with networks of data comparable to those used by MBH98.

        Question 36. Have you ever received any communications that
    suggested that there might be computational errors in MBH98 or MBH99?
    Please provide such communications together with any responses.
        Response. I receive many emails, often from list-serves of self-
    professed ``climate skeptics'' making numerous spurious claims against
    my work and that of many of my colleagues. I have received no
    correspondence providing credible evidence of any errors in our work.
    Nor has any such credible evidence been published in the peer-reviewed
    scientific literature.

        Question 37. Did the peer reviewers for Nature in MBH98 carry out
    any independent quality control or validation studies? If so, please
    provide copies of such reports.
        Response. Neither I, nor authors of peer-reviewed journal articles
    in general, are made privy to the detailed analyses that peer reviewers
    may or may not have performed in the process of reviewing a manuscript.
    Authors only receive the comments that were selected to be made
    available to them by the reviewer and editor. This question is thus
    impossible to answer. Numerous other groups (see the dozen or so
    independent estimates of various groups shown in Figure 1 of: Mann,
    M.E., Ammann, C.M., Bradley, R.S., Briffa, K.R., Crowley, T.J., Hughes,
    M.K., Jones, P.D., Oppenheimer, M., Osborn, T.J., Overpeck, J.T.,
    Rutherford, S., Trenberth, K.E., Wigley, T.M.L., On Past Temperatures
    and Anomalous Late 20th Century Warmth, Eos, 84, 256-258, 2003) have
    produced reconstructions that are remarkably similar to those of MBH98
    based on a variety of data and methods. See my answer to Question No.
    4.

        Question 38. 38. Did the peer reviewers for Geophysical Research
    Letters in MBH99 carry out any independent quality control or
    validation studies? If so, please provide copies of such reports.
        Response. See response to Question No. 37.

        Question 39. How many people have requested the underlying digital
    information in MBH98? Please provide dates of such requests and dates
    of your reply.
        Response. My collaborators and I have not kept a specific record.
    The data has been provided to any scientific groups that have requested
    it, and has been made available on an open access basis through a
    public ftp site: ftp://holocene.evsc.virginia.edu/pub/MBH98/, since
    July 2002.

        Question 40. Were you one of the primary or lead authors of IPCC/
    TAR chapter 2?
        Response. The convening lead authors of chapter 2 of the IPCC TAR
    were Dr. Chris Folland and Thomas Karl. I was one of eight additional
    co-authors contributing to chapter 2.

        Question 41. In your capacity as IPCC/TAR author, did you prepare
    any drafts that referred to your own papers? Please provide all drafts
    that you prepared for IPCC.
        Response. I contributed to numerous sections of the chapter and
    provided contributions that referenced the work of the leading
    paleoclimatologists, which includes me and many of my colleagues. Those
    interested in drafts of IPCC chapters should inquire of the appropriate
    IPCC working group. I am not in possession of such drafts, and even if
    I were, I would not be at liberty to distribute the various drafts of
    the chapters of the report.

        Question 42. Was any language from your drafts referring to your
    own reports ultimately used by IPCC/TAR? Please provide highlighted
    versions from IPCC.
        Response. The wording of the question is unclear. If the question
    is, did I, in my contributions to the chapter, provide summaries that
    included references to my own work as well as that of other scientists,
    the answer is of course yes. Since each of the authors was asked to
    contribute sections related to their particular areas of expertise, and
    since the IPCC authors were chosen from among the leading scientists in
    the world, it would be distinctly odd if it were not the case that most
    authors referred to their work, as well as that of others, in their
    contributions.

        Question 43. Did IPCC/TAR have any policies governing how lead
    authors used their own work? Did IPCC/TAR have any quality control
    procedures in the event that a lead author used his own work? Please
    provide a short summary of your understanding of such procedures.
        Response. I am not a spokesperson for the IPCC. However, it is my
    understanding that the IPCC carries out a process for developing its
    summarization of the understanding of science that leads to one of the
    most rigorously peer-reviewed scientific documents in existence.
    Individual technical chapters are prepared by expert scientific teams
    that consider the full range of published papers in a subject area.
    This expert author team then solicits an initial peer review from a
    large number of other scientists in the field, drawing on those
    representing the full range of expert science. The reports next go
    through a much wider review that is open to literally thousands of
    scientists around the world. Finally countries, NGO's, and professional
    groups (such as business groups) are provided the opportunity to send
    in review comments. (and in the case of the U.S. government review, an
    invitation to submit comments to be considered to be forwarded to the
    IPCC is published in the Federal Register, enabling all to participate
    in this review). With the comments available at each stage of the
    review process, the authors consider each comment and document their
    response. The meticulousness and fairness of the revision process by
    the authors in response to reviewer comments is evaluated by an
    independent pair of ``review editors'' who are themselves top
    international climate scientists who are not authors of the report
    itself. The National Academy of Sciences, at President George W. Bush's
    request, and other national academies around the world have
    independently reviewed the process and the validity of the scientific
    findings of the IPCC and endorsed them.

        Question 44. Did MBH98 and MBH99 use any proxy series, which were
    either unpublished or which resulted from unpublished calculations,
    which you carried out? If so, please identify, and detail how you
    verified those unpublished results.
        Response. MBH98 and MBH99, as many studies, made use of newly
    available data that had not yet been published by the original authors
    providing those data, and thus was provided to Mann and colleagues on a
    provisional basis that they not release the data until the authors had
    a chance to publish the records themselves. After all of the data used
    had been published, the full dataset used by MBH98 and MBH99 was made
    available in the public domain on the public website: ftp://
    holocene.evsc.virginia.edu/pub/MBH98/

        Question 45. Despite solar variability over the last two millennia,
    your analysis concludes the Northern Hemisphere average temperature has
    remained virtually constant. What mechanism or mechanisms are
    responsible for negating the influence of the sun? Do climate models
    (GCMs) exhibit the same lack of response to solar forcing that your
    analysis implies? If not, why are model simulations at variance with
    your conclusions and how does that limit their applicability for future
    climate scenario assessments?
        Response. The question is falsely premised on several levels. No
    reasonable description of the reconstructions that we or others have
    produced of temperature variations in past centuries would characterize
    them as ``virtually constant''. The reconstructions performed by my
    group and others indicate an amplitude of variability that consistent
    with expectations from models driven with estimates of past radiative
    forcing including solar and radiative forcing, and allowing for the
    added role of internal unforced variability [see e.g. Crowley, T.J.,
    Causes of Climate Change Over the Past 1000 Years, Science, 289, 270-
    277, 2000]. Indeed, it has been shown that the model-predicted pattern
    of surface temperature response to solar forcing in past centuries
    closely resembles that estimated from the temperature reconstructions
    that my colleagues and I have performed [Shindell, D.T., Schmidt, G.A.,
    Mann, M.E., Rind, D., Waple, A., Solar forcing of regional climate
    change during the Maunder Minimum, Science, 294, 2149-2152, 2001;
    Waple, A., Mann, M.E., Bradley, R.S., Long-term Patterns of Solar
    Irradiance Forcing in Model Experiments and Proxy-based Surface
    Temperature Reconstructions, Climate Dynamics, 18, 563-578, 2002;
    Shindell, D.T., Schmidt, G.A., Miller, R., Mann, M.E., Volcanic and
    Solar forcing of Climate Change During the Pre-Industrial era, Journal
    of Climate, in press, 2003].

        Question 46. How did the temperatures of the mid-Holocene Optimum
    Period (6000 to 9000 BP) compare with those observed today? Was it a
    global or a local phenomenon? What was or were the cause or causes of
    any temperature anomalies in that period? What is the cause of the 104
    to 105 year timescale changes in deuterium, oxygen isotope, etc.,
    concentrations in ice core records? Are such changes global or local?
        Response. Paleoclimate experts have established that mid-Holocene
    warmth centered roughly 5000 years ago was restricted to high latitudes
    and certain seasons (summer in the Northern Hemisphere and winter in
    the southern hemisphere). Because much of the early paleoclimate
    evidence that was available (for example, fossil pollen assemblages)
    came from the Northern Hemisphere extratropics, and is largely
    reflective of summer conditions, decades ago some scientists believed
    that this was a time of globally warmer conditions. It is now well
    known that this is not the case. More abundant evidence now
    demonstrates, for example, that the tropical regions were cooler over
    much of the year. All of these changes are consistent with the expected
    response of surface temperatures to the known changes in the Earth's
    orbital geometry relative to the Sun during that time period and
    associated climate feedbacks, as detailed in peer-reviewed scientific
    publications [e.g., Hewitt, C.D., A Fully Coupled GCM Simulation of the
    Climate of the Mid-Holocene, Geophysical Research Letters, 25 (3), 361-
    364, 1998; Ganopolski, A., C. Kubatzki, M. Claussen, V. Brovkin, and V.
    Petoukhov, The Influence of Vegetation-Atmosphere-Ocean Interaction on
    Climate During the Mid-Holocene, Science, 280, 1916-1919, 1998].
        Climate model simulations indicate quite good agreement with
    paleoclimate evidence now available. These models calculate that global
    annual average temperatures were probably about the same or a few
    tenths of a degree C cooler than today (the late 20th century) during
    this time period [Ganopolski, A., C. Kubatzki, M. Claussen, V. Brovkin,
    and V. Petoukhov, The Influence of Vegetation-Atmosphere-Ocean
    Interaction on Climate During the Mid-Holocene, Science, 280, 1916-
    1919, 1998; Kitoh, A., and S. Murakami, Tropical Pacific Climate at the
    mid-Holocene and the Last Glacial Maximum simulated by a coupled
    oceanatmosphere general circulation model, Paleooceanography, 17 (3),
    (19)1-13, 2002.]. That's a far cry from the very out-of-date claim made
    by Dr. Legates in his testimony. Dr. Legates' comments regarding
    climate changes over the past 1000 years reflect a similar lack of
    familiarity with a whole body of paleoclimate research, especially with
    the new insights gained through the augmented research program, during
    the past decade.

        Question 47. It has been observed that in the past, carbon dioxide
    concentrations have sometimes lagged air temperature trends; that is,
    changes in air temperature have subsequently sometimes resulted in
    changes in carbon dioxide concentrations. Do you agree with those
    results from expert researchers? Why or why not?
        Response. The question mis-characterizes the evidence that has been
    provided by paleoclimate researchers. The studies that the questioner
    appears to be alluding to, demonstrate a phase relationship between ice
    core CO2 estimates and *local* temperature variations at the
    site of the ice core. Furthermore these local temperature estimates are
    indirectly inferred from oxygen isotopes, based on quite uncertain
    assumptions regarding oxygen isotope paleothermometary and neglecting
    possible biases due to the variable seasonality of local accumulation.
    As local temperature variations at the site of the ice core have an
    unknown relationship with global mean temperature variations (which are
    far more dominated by lower latitudes which occupy the majority of the
    Earth's surface area), the phase relationships between past CO2
    and global mean temperature variations are not known. In spite of these
    qualifications, it is not at all implausible that the geologic record
    indicates that at some times the CO2 increase may lag the
    initial temperature increase; such a situation would be expected, for
    example, if the change in climate was initiated by a change in the
    orbital geometry that affected the distribution of solar radiation, and
    then the slow warming drove CO2 from the warming ocean into
    the atmosphere. It is because of the many possibilities for how
    different processes can interact that it is essential to not simply
    base a conclusion on an apparent correlation without evaluating the
    underlying physical mechanisms for that particular period.

        Question 48. Are there any time periods for which atmospheric
    CO2 content has changed without a concomitant change in
    global air temperature? Are there periods when the atmospheric CO2
    content was relatively high butglobal air temperatures relatively low?
        Response. In his testimony, Dr. Legates indicated that there were
    historical cases where the temperature has gone up, but that CO2
    has fallen. It may well be the case that this has happened in the past.
    However, it is hardly surprising, and certainly not inconsistent with
    our established understanding of the various factors that influence
    surface temperatures. The warming response to increased greenhouse gas
    concentrations lags the actual increase in greenhouse gas
    concentrations in the atmosphere potentially by several decades, due to
    the sluggish response of the oceans, which have an enormous thermal
    capacity compared to the atmosphere, to increased surface radiative
    forcing. So warming is not expected to be contemporaneous with changes
    in CO2, but instead, to lag it by several decades. However,
    greenhouse gases are certainly not the only factor affecting the
    average surface temperature of the Earth. There are other anthropogenic
    factors, such as increased sulphate aerosols, which can have a cooling
    effect on the climate, and natural factors, such as volcanic activity,
    modest natural variations in solar output, and internal dynamics
    associated with climate events such as El Nino, which also influence
    the average surface temperature of the globe. At any particular time,
    these other factors may outweigh the warming effect due to increased
    greenhouse gases. For example, the relative lack of warming during the
    period 1940-1970 appears to be related to a combination of such
    factors, as discussed in my response to an earlier question. But while
    these other factors tend to cancel over time, the increased greenhouse
    gases lead to a systematic warming that will not cancel out over a very
    long time period. It is for precisely this reason that late 20th
    century warming now appears to have risen above the range of the
    natural variability of past centuries.

        Question 49. Two independent and nearly direct measures of surface
    temperature (deep borehole reconstructions) over the past several
    millennia have been published for Greenland (Dahl-Jensen et al 1998)
    and the Middle Urals (Demeshko and Shchapov 2001). The local surface
    temperature at these locations is highly correlated with global
    temperature on 10-year time scales and longer (r2 > 50 percent 10 yr
    with agreement increasing for longer averaging periods). Both
    reconstructions independently show their local surface temperatures
    were at least a1 + C warmer for century-scale mean temperatures around
    A.D. 900 than the latter half of the 20th century, translating into a
    global anomaly of at least +0.2+ C relative to today.
        This further implies that even higher global temperature anomalies
    for shorter periods, such as half-century or decadal periods, were
    observed about 1000 years ago. Why do these two robust measures of
    local and global approximations differ greatly from Mann et al. 1999?
        Response. The question is wrongly premised on multiple levels.
    First, the correlations cited are completely wrong. No citation to the
    peer-reviewed literature is provided, so it is difficult to determinate
    how these numbers were arrived at. I therefore proceeded to analyzed
    the appropriate surface air temperature gridpoint data from the
    Climatic Research Unit of the University of East Anglia myself. I found
    that only after 1922 is there adequate coverage (>50 percent areal
    coverage) to estimate a meaningful Greenland areal-mean temperature.
    For the period back to 1922, the linear correlation between the
    Greenland and Northern Hemisphere mean temperature is r= -0.06
    (negative!), nor is there a significant correlation at decadal or
    longer timescales. In fact, the trends in the two series during the
    latter 20th century are of opposite sign. So the numbers cited are
    completely spurious.
        It is in fact well known by the climate community that there are
    fundamental physical reasons why temperatures in Greenland are, in
    general, poorly correlated with Northern Hemisphere mean temperature.
    Owing to the strong overprint of processes, such as the North Atlantic
    Oscillation, and changes in coupled ocean-atmosphere processes in the
    North Atlantic that impart a large regional overprint of temperature
    variation in this region, both negative and positive correlations with
    Northern Hemisphere mean temperature can be found, depending on the
    time period and region of Greenland analyzed.
        The Dahl Jensen et al Greenland borehole data may indeed be useful
    temperature proxy data for the regions they represent, and they have
    been used in reconstructions of Northern Hemisphere mean temperature,
    with caveats due to their extremely low temporal resolution (see Mann
    and Jones, 2003). While the two Greenland borehole records show
    significantly different histories over the past 1000 years (which is
    expected since temperature trends vary markedly depending on the region
    of Greenland in question), one of the two records does correlate well
    with the instrumental Greenland record over the period of mutual
    overlap. Its shows the mid-20th century warm peak, followed by the
    latter 20th century cooling peak, just as the instrumental Greenland
    annual mean temperature record does. However, instrumental Northern
    Hemisphere mean temperature has, in contrast, warmed markedly during
    the latter 20th century.
        The Greenland borehole temperature reconstruction may tell us
    something about temperatures in Greenland over the past few millennia
    even though the two different Greenland borehole records show some
    differences between them. But these results are unlikely to tell us
    much, if anything, about Northern Hemisphere mean temperature trends.
    Indeed, Dahl-Jensen et al have never, to my knowledge, claimed in their
    studies that that temperature variations in the two regions of
    Greenland reconstructed (which themselves show significantly different
    histories over the past 1000 years) are representative of Northern
    Hemisphere mean temperatures, and I would be surprised if the authors
    were comfortable in having their data represented as such.

        Question 50. In your view what should the Federal Government do in
    response of rising concentrations of CO2? What would be the
    climate impact of this effort?
        Response. In my view, the Congress and the Federal Government
    should be taking the scientific findings of the mainstream research
    community very seriously and should stop focusing so much attention on
    the poorly conducted and distracting nitpicking of the various
    contrarian scientists. The IPCC assessments represent the most
    authoritative reviews of the science and have been unanimously endorsed
    by all of the participating nations of the world--it is time to pay
    attention to their findings. Exactly what steps should be taken and how
    fast this should be done are policy questions that members of this body
    should be responsibly and thoughtfully addressing. The long residence
    timescales of anthropogenic greenhouses gases, and the lags in the
    response of the climate system (e.g. sea level rise) to already
    realized increases in greenhouse gas concentrations dictate, however,
    that there are potentially significant costs to delayed action.

        Question 51. Approximately what percentage of the temperature
    increase in the observational record over the last 100 years would you
    attribute to anthropogenic causes? What percentage would you attribute
    to increased urbanization? What percentage would you attribute to non-
    urbanized land use changes? What percentage would you attribute to
    natural (solar, volcanic, etc.) variability? What percentage would you
    attribute to ``internal'' climate variability? What percentage would
    you say results from other or unexplained sources? Give estimates for
    the years 1900,1940, 1980 and 2000.
        Response. A cursory review of the available evidence (see e.g.
    Figure 2.1 of chapter 2 of the 2001 IPCC Scientific Working Group
    report) indicates the following approximate attributes in the observed
    record of global mean temperature changes over the past 100 years: a
    warming of approximately 0.3+ C to 1940, a statistically insignificant
    change (given the uncertainties) from 1940 to the mid-1970's, and then
    an additional warming of approximately 0.5+ C from 1970 to 2000. This
    pattern of behavior is reproduced closely by models driven with
    estimates of both natural and anthropogenic forcing of the climate
    during the 20th century. The period of relative stasis in global mean
    temperatures from 1940 to 1970, in these model simulations, appears to
    result from the cooling impact of anthropogenic aerosols (for which
    there was a large increase during that time period) as well as a
    potential cooling contribution from explosive volcanic eruptions that
    occurred during that period, which tended to offset the warming
    influence of increased greenhouse gas concentrations during that time
    period (e.g. the 1957 eruption). However, much of the overall warming
    of the globe during the 20th century (which is between 0.6+ C and 1.0+
    C depending on the precise instrumental data set used, and the precise
    endpoints of the interval examined) is clearly a result of increased
    greenhouse gas concentrations, as established in these simulations,
    consistent with the conclusions of the IPCC Third Assessment Report
    that most of the warming of the past 50 years is attributable to human
    influences.

        Question 52. What was the earth's climate like the last time the
    atmospheric concentration of carbon dioxide was near today's level of
    about 370 parts per million (ppm) and what were past conditions like
    when concentrations were at 550 ppm? Detail the factors that cause the
    global carbon cycle to produce these high levels of atmospheric carbon
    dioxide.
        Response. It is not precisely known what the ``earth's climate''
    was like the last time carbon dioxide levels were near 370 ppm (let
    alone 550 ppm) because the available paleoclimate evidence available
    this long ago are quite uncertain and incomplete. That having been
    said, it is believed, based on the available proxy information and
    faunal/floral evidence, that global temperatures were probably several
    degrees higher than they are today when CO2 concentrations
    neared 550 pm, roughly consistent with model simulation results. One
    probably has to go back roughly 40-50 million years ago (see chapter 3
    of the 2001 IPCC working group 1 report) to find a time when CO2
    concentrations were in the range of 550 ppm (i.e., roughly double their
    pre-industrial concentration) and approximately 80 million years ago
    (i.e., the mid-Cretaceous period when Dinosaurs roamed the polar
    regions) to find a time when CO2 levels were in excess of
    1200 ppm (a level that will be reached, at current rates of CO2
    increase, within 1 to 1\1/2\ centuries). Proxy evidence available for
    this period, tenuous though it is, suggests deep ocean temperatures 8-
    12+ C warmer than present. State of the art climate model simulations
    performed by Bette Otto-Bleisner and colleagues using the National
    Center for Atmospheric Research (NCAR) global climate model, which
    incorporate such CO2 levels (and the continental
    configuration corresponding to the mid-Cretaceous period), indicate
    significantly warmer sea surface temperatures, with tropical sea
    surface temperatures approximately 4+ C warmer and polar sea surface
    temperatures approximately 6-14+ C warmer than present. The simulations
    indicate an absence of perennial sea ice at even the most polar
    latitudes.

        Question 53. In your vitae, you indicate that you serve on the
    panel for NOAA's Climate Change Data and Detection (CCDD) program,
    while at the same time, you also have received large grants from this
    program. Please explain your role on the panel, how grant submissions
    are evaluated, and why there is no conflict of interest or impropriety
    associated with members of a panel receiving large grants from the
    program for which they serve.
        Response. I am not a spokesperson for NOAA, and would suggest that
    the questioner contact the appropriate NOAA agency officials for
    further information on their conflict of interest and disclosure
    policies. That notwithstanding, however, I would note the following
    points. Government funding agencies seek to draw upon the leading
    experts of the field in their panels. Inevitably, this means that
    specific science programs within NSF and NOAA invite to their review
    panels scientists who typically submit proposals themselves to those
    panels. Scientists are also asked to disclose any conflicts of interest
    they might have in reviewing a proposal, and are asked to recuse
    themselves from any participation in discussions related to proposals
    that they might have even peripheral involvement with. In my
    involvement in both NSF and NOAA panel reviews, I have on many
    occasions recused myself from reviewing or discussing a proposal based
    on such considerations.

        Question 54. Do you receive any income or reimbursement (travel,
    speaking fees, etc.) from any sources, which have taken advocacy
    positions with respect to the Kyoto Protocol, the U.N. Framework
    Convention on Climate Change, or legislation before the U.S. Congress
    that would affect greenhouse gas emissions? If so, please identify
    those sources and the approximate amount of money that they represent.
        Response. All income or travel expense reimbursement funds that I
    have received to my recollection have come from academic institutions,
    government funding agencies such as NSF, NOAA, NASA, DOE, and
    scientific organizations such as the American Geophysical Union and
    University Corporation for Atmospheric Research (UCAR). I am not
    familiar with any advocacy positions that have been taken by any of
    these institutions or organizations regarding the U.N. Framework
    Convention on Climate change, or legislation before the U.S. Congress
    that would affect greenhouse gas emissions.

                                   __________

    Responses by Michael Mann to Additional Questions from Senator Jeffords

        Question 1. Is it your understanding that during the mid-Holocene
    optimum period (the period from 4000-7000 B.C.) that annual mean global
    temperatures were more than a degree C warmer than the present day?
        Response. This is an oft-repeated but patently false claim. Dr.
    Legates, who has no established expertise in the relevant field of
    paleoclimatology, indeed asserts that temperatures were warmer at this
    time. In fact, not only is that not the consensus of the paleoclimate
    research community, but just the opposite is believed to be true of
    global annual mean temperatures at this time. Paleoclimate experts know
    that the mid-Holocene warmth centered roughly 5000 years ago was
    restricted to high latitudes and certain seasons (summer in the
    Northern Hemisphere and winter in the southern hemisphere). Because
    much of the early paleoclimate evidence that was available (for
    example, fossil pollen assemblages) came from the Northern Hemisphere
    extratropics, and is largely reflective of summer conditions, decades
    ago some scientists believed that this was a time of globally warmer
    conditions. It is now well known that this is not the case. More
    abundant evidence now demonstrates, for example, that the tropical
    regions were cooler over much of the year. All of these changes are
    consistent with the expected response of surface temperatures to the
    known changes in the Earth's orbital geometry relative to the Sun
    during that time period and associated climate feedbacks, as detailed
    in peer-reviewed scientific publications [e.g., Hewitt, C.D., A Fully
    Coupled GCM Simulation of the Climate of the Mid-Holocene, Geophysical
    Research Letters, 25 (3), 361-364, 1998; Ganopolski, A., C. Kubatzki,
    M. Claussen, V. Brovkin, and V. Petoukhov, The Influence of Vegetation-
    Atmosphere-Ocean Interaction on Climate During the Mid-Holocene,
    Science, 280, 1916-1919, 1998].
        Climate model simulations indicate quite good agreement with
    paleoclimate evidence now available. These models calculate that global
    annual average temperatures were probably a few tenths of a degree C
    cooler than today during this time period [Kitoh, A., and S. Murakami,
    Tropical Pacific Climate at the mid-Holocene and the Last Glacial
    Maximum simulated by a coupled ocean-atmosphere general circulation
    model, Paleooceanography, 17 (3), (19)1-13, 2002.]. That's a far cry
    from the very out-of-date claim made by Legates. Legates' comments
    regarding climate changes over the past 1000 years reflect a similar
    lack of familiarity with a whole body of paleoclimate research,
    especially with the new insights gained through the augmented research
    program, during the past decade.

        Question 2. Why only focus on the past 1000 or 2000 years and not
    further back?
        Response. Large changes in climate certainly occurred in the
    distant past. If we look million years back in time, dinosaurs were
    roaming the polar regions of the Earth, and the globe was several
    degrees wanner than today. Carbon dioxide levels were probably several
    times their current level, slowly having attained such high levels due
    to changes in the arrangements of the continents (`plate tectonics')
    which influence the volcanic outgassing of carbon dioxide from the
    solid Earth. These changes occurred on timescales of tens of millions
    of years. Going back 10,000 years ago, large ice sheets existed over
    North America due to natural changes that occur in the Earth's orbit
    around the Sun on timescales of tens of thousands of years. Trying to
    study distant past climates for insights into modern natural climate
    variability is hampered by the fact that the basic external constraints
    on the system (the continental arrangement, the geometry of the Earth's
    astronomical orbit, the presence of continental ice sheets--what we
    call the `boundary conditions') were significantly, different from
    today. Focusing on the evolution of climate in the centuries leading up
    to the 20th century (i.e., the past 1000 to 2000 years) provides a
    perspective on the natural variability of the climate prior to the
    period during which large-scale human influence is likely to have
    occurred, yet modern enough that the basic boundary conditions on the
    climate system were otherwise the same. This provides us, in essence,
    `control' for diagnosing whether or not recent changes in climate are
    indeed unusual. Moreover, only during the past 1000-2000 years do we
    have adequate networks of proxy climate data with the required (annual)
    resolution in time to compare and validate against modern instrumental
    records; Reliable quantitative reconstructions of large-scale surface
    temperature patterns further back in time are thus not, at present,
    possible.

        Question 3. One of the Northern Hemisphere temperature
    reconstructions in your Figure 1 (the green curve from a paper by Esper
    and colleagues from Science in 2001) shows larger swings in past
    centuries, marginally outside the uncertainty bounds of the other
    reconstructions and model simulations. Does this indicate internal
    inconsistency in our knowledge?
        Response. There is no inconsistency. Esper et al noted, in their
    paper, that their estimate, unlike that of my colleagues and mine (the
    Mann/Bradley/Hughes or ``MBH'' reconstruction), was not representative
    of the entire Northern Hemisphere. They explicitly noted this in their
    paper, where they pointed out the likely reason for differences is that
    the MBH reconstruction represents the full Northern Hemisphere
    (tropics, subtropics, and extratropics) while the Esper et al
    reconstruction only represents the restricted extratropical continents.
    In fact, in a Science article that appeared in the same issue as the
    Esper et al paper [Briffa, K.R. and T.J. Osborn, Science, Blowing Hot
    and Cold, 295, 2227-2228, 2002] Briffa and Osborn noted that much of
    the difference was due to an arguably inappropriate scaling that Esper
    et al used, and an inappropriate comparison of summer vs. annual
    temperatures; ``when we regressed the record of Esper et al. against
    non-smoothed data (see the figure), this difference (with MBHJ was
    reduced to about 0.4+ C. Recalibrating both curves against year-by-year
    warm season temperatures reduces this difference further to about 0.35+
    C.''
        As shown in the ``Eos''article discussed in my testimony, which
    represents a consensus of the leading researchers in the field [Mann,
    ME, Ammann, C.M., Bradley, R.S., Briffa; K.R., Crowley, T.J., Hughes,
    M.K.; Jones, P.D., Oppenheimer, M., Osbom, T.J., Overpeck, J.T.,
    Rutherford, S., Trenberth, K.E., Wigley, T.M.L., On Past Temperatures
    and Anomalous Late 20th Century Warmth, Eos, 84, 256-258, 2003], a
    proper scaling of Esper et al record prior to comparison with other
    estimates, shows it only marginally outside the error estimates of the
    MBH reconstruction and the many other estimates that are in agreement
    with it. As noted in two articles in Science that shortly followed the
    Esper et al paper [Mann, M.E., Hughes, M.K., Tree-Ring Chronologies and
    Climate Variability, Science, 296, 848, 2002; Mann, ME, The Value of
    Multiple Proxies, Science, 297, 1481-1482, 2002], it is likely that the
    emphasis of the Esper et al reconstruction on only the summer season
    and the extratropical continental regions, provides a biased estimate
    of the true pattern of annual, hemisphere-wide temperatures in past
    centuries, explaining the small differences between this estimate and
    other estimates. This conclusion has been verified in recent modeling
    studies [Shindell, D.T., Schmidt, G.A., Miller, R., Mann, M.E.,
    Volcanic and Solar forcing of Climate Change During the Pre-Industrial
    era, Journal of Climate, in press, 2003 ]. It is thus clearly
    disingenuous when contrarians make the argument that the Esper et al
    result is in conflict with the mainstream conclusions of the climate
    research community with regard to the history of Northern Hemisphere
    mean annual temperature variations over the past millennium as
    embodied, for example, in the Eos article.

        Question 4. As climatologist, can you explain what kind of
    quantitative analysis it takes to determine whether or not the last 50
    years has been unusually warm compared to the last 1000 years?
        Response. Well, such an analysis requires the careful use of proxy
    data, because we don't have widespread instrumental temperature records
    prior to the mid-19th century. By `careful use': I mean that one must
    first establish that the records actually resolve the changes of the
    past 50 years. This typically requires annually resolved proxy records
    or the very circumspect use of records with decadal resolution. One
    must not, as in the Soon and Baliunas' studies, use records that do not
    resolve the trends of the past few decades. One must also establish the
    existence of an actual temperature signal in the available proxy data
    before using them to reconstruct past temperature patterns, and one
    must properly synthesize regional data, which typically all show
    different tendencies at any given time, into an estimate of the average
    temperature over the entire hemisphere or globe. There area number of
    ways of performing such a synthesis, from the sophisticated pattern
    reconstruction approaches my colleagues and I have described in the
    technical literature, to the relatively straightforward compositing
    approach that many other paleoclimatologists, (including myself) have
    also used. In all cases, the estimates based on the proxy data must be
    calibrated against modern instrumental temperature measurements, to
    allow, for a quantitative estimate of past temperatures. The estimate
    must then be independently verified or, what we call, `cross-
    validated,' by showing that it independently reproduces earlier
    instrumental data that were not used to calibrate the estimates.
    Finally, uncertainties must be diagnosed based on how well the
    reconstruction describes actual available instrumental measurements.
    Once such steps have been taken, it is possible to compare the recent
    instrumental record to the reconstruction within the context of the
    uncertainties of the reconstruction. This latter comparison allows us
    to gauge whether or not late 20th century temperatures are anomalous or
    not in a long-term context. The conclusion from legitimate such studies
    that late 20th century warmth is indeed anomalous in a millennial or
    longer-term context has been shown to be quite robust with respect to
    the details of the data set used, or the methodology used (as shown in
    exhibit 1 in my testimony, the first figure of the ``Eos'' piece). It
    is noteworthy that the Soon and Baliunas paper satisfies none of the
    required standards for a `careful use of proxy data' specified above.

        Question 5. Do you claim that appropriate statistical methods do
    not exist for calibrating statistical predictors, including climate
    proxy records, against a target variable, such as the modern
    instrumental temperature record?
        Response. No. The statement belies a centuries-old field of
    statistics known as ``multivariate linear regression'' in which a set
    of candidate ``predictors'' (such as proxy data) are statistically
    related to a target variable or ``predictand'' (such as the
    instrumental temperature record) during a common interval of overlap
    (e.g., the 20th century). If done properly, this statistical method
    isolates the temperature information that is contained within the proxy
    data, and uses that information to reconstruct past temperature
    patterns from the proxy data. It is also well known to those properly
    trained in statistics that the ``regression model'' must be
    independently ``validated'' by showing that it successfully reproduces
    independent data (e.g. longer-term instrumental temperature records)
    that were not used in constructing the statistical model itself. The
    estimates by Mann and colleagues embrace each of these fundamental
    statistical principles.
        Legates in his testimony seemed to claim that a composite estimate
    (e.g. of Northern Hemisphere mean temperature) should somehow resemble
    each of the individual predictors (e.g. the various regional
    temperature estimates). Such a result is, in general, a statistical
    impossibility. There is a basic theorem in statistics known as the
    ``central limit theorem'' which indicates a general tendency for a
    composite (i.e. average) of a large number of different individual
    estimates to cancel out in terms of the pattern variation and amplitude
    of variability evident in the individual estimates. If Legates were
    indeed (as he claims to be) familiar with the instrumental surface
    temperature record, he would know, for example, that individual
    instrumental thermometer records available for particular locations
    over the globe during the 20th century show very little in common with
    the `composite' series constructed by averaging all of the individual
    records into a hemispheric or global estimates. Because season-to-
    season and year-to year fluctuations in the climate at regional scales
    often result from shifts in the atmospheric circulation, not every
    location experiences the same variation in any given year; for example,
    this summer, the western United States and Europe are anomalously warm,
    while the East Coast is anomalously cool. The average series reflects a
    tendency for a cancellation of the various ``ups'' and ``downs'' in the
    different individual series that often occur at different times. This
    is simply a statement about the instrumental record itself, and
    requires no use of proxy data at all. It is discouraging that Legates
    and colleagues haven't performed even such simple analyses with
    available instrumental data that would expose the fundamental flaws in
    their supposed `statistical' reasoning.
        In this context, it should be noted that Legates testimony
    seriously misrepresents the statistical analyses used by Mann and co-
    workers. In his testimony, Legates claimed that my collaborators and I
    replaced the proxy data for the 1900's by the instrumental. The
    assertion is simply factually incorrect. Any reader of our published
    work knows full well that our proxy-based temperature reconstruction
    extends well into the late 20th century, through 1980 (the vast
    majority of published high-resolution climate proxy data are not
    available at later times than this). It is shown in our work that the
    reconstruction independently reproduces estimates from the instrumental
    surface temperature data record back through the mid-19th century and,
    in certain regions, back through the mid-18th century (i.e., our
    regression model is ``validated'' in the manner discussed above). Our
    Northern Hemisphere average temperature series reconstructed from proxy
    data is shown to agree with the instrumental Northern Hemisphere
    average record over the entire interval available for comparison (1856-
    1980). This successful validation of the reconstruction, furthermore,
    allows us to compare the proxy-based reconstruction to the entire
    instrumental record (available through 1999 at the time of our
    publication), taking into account the uncertainties in the
    reconstruction.
        Legates further claim that we present the instrumental record
    without uncertainty is disingenuous. If Legates, for example, were
    familiar with studies of the instrumental surface temperature record,
    he would understand that the uncertainties in this record using the
    20th century are minimal compared to the uncertainties shown for our
    reconstruction [see e.g. Figure 2.1b in Folland, C.K., Karl, T.R.,
    Christy, J.R., Clarke, R. A.,Gruza, G.V., Jouzel, J., Mann, M.E.,
    Oerlemans, J., Salinger, M.J.;, Wang, S.-W., Observed Climate
    Variability arid: Change, in Climate Change 2001: The Scientific Basis,
    Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 99-
    181, 2001.]. Furthermore, all scientists with a proper training in
    statistics know that uncertainties add ``in quadrature'', In other
    words, you have to square them before adding them. This means that the
    relatively small uncertainty in the instrumental record makes a
    relatively small contribution to the total uncertainty. Legates claimed
    in his testimony that including the uncertainty in the instrumental
    record, which he estimates as 0.1+ C would change the conclusions
    expressed by us and other mainstream climate scientists that the 1990's
    are the warmest decade in at least the past 1000 years within estimated
    uncertainties. This claim is very misleading for several reasons,
    First, the standard error in Northern Hemisphere mean annual
    temperatures during the 1990's is far smaller than the amount cited, by
    Legates [see again Folland et al, 2001 cited above]. Even more
    problematic, however, Legates claim indicates a fundamental
    misunderstanding of the statistical concepts of standard error and
    uncertainty,. The shaded region shown along with the Mann et al
    reconstruction (and other similar plots shown in recent articles such
    as the aforementioned ``Eos'' article, and the IPCC report) indicate
    two standard error intervals. The decade of the 1990's is roughly two
    standard errors warmer (i.e., about 0.4+ C) than any decade prior to
    the 20th century in the reconstruction. Based on a one-sided test for
    anomalous warmth, this translates to a roughly 97.5 percent level of
    significance. Modifying the uncertainties to include the small
    additional contribution due to uncertainties in the instrumental record
    itself would modify this only slightly, and would not lower the
    significance level below the 95 percent level. Though there is no such
    thing as an absolute estimate of uncertainty, despite Legate's
    implications to the contrary, a 95 percent confidence is often adopted
    as an appropriate criterion for significance. Legates statement that
    including instrumental contributions to the uncertainty would change
    the conclusions is thus clearly false.

        Question 6. In determining whether the temperature of the
    ``Medieval Warm Period'' was warmer than the 20th century, does your
    work analyze whether a 50-year period is either warmer or wetter or
    drier than the 20th century? Is it appropriate to use indicators of
    drought and precipitation directly to draw inferences of past
    temperatures?
        Response. No, the work of me and my colleagues does not follow the
    flawed approach used by Soon and Baliunas. It is fundamentally unsound
    to infer past temperature changes directly from records of drought or
    precipitation. The analysis methods used by my various collaborators
    and I (e.g. the 13 authors of the recent article in Eos) employ
    standard statistical methods for identifying the surface temperature
    signal contained in proxy climate records, and using only that
    temperature signal in reconstructing past temperature patterns. By
    contrast, Soon and Baliunas simply infer evidence for warm ``Medieval
    Warm Period'' or cold ``Little Ice Age'' conditions from the relative
    changes in proxy records often reflective of changes in precipitation
    or drought, rather than temperature. It is difficult to imagine amore
    basic mistake than misinterpreting hydrological evidence in terms of
    temperature evidence. This fundamental shortcoming in their approach is
    identified in the Eos article referred to in my testimony that was
    written by 13 leading climate and paleoclimate scientists.
    Incidentally, the Eos piece was peer-reviewed, despite the claim by
    Legates otherwise in his testimony--an associate editor with training
    in the particular field corresponding to the submitted piece
    (``Atmospheric Science'' in this case); reviews the content of Eos
    forum pieces prior to acceptance.

        Question 7. Can you compare the quantitative analysis that supports
    your conclusion that the climate is warming faster in recent years than
    at any time in the recent past with the analysis done in the Soon
    literature review?
        Response. Technically speaking, there is no actual ``analysis'' in
    the Soon and Baliunas review, in that they don't appear to have
    performed a single numerical or statistical operation upon a single
    time series at all. They do not provide any quantitative estimates of
    temperature changes, let alone any estimate of uncertainties, Instead,
    they claim to interpret the results of past studies mainly by counting
    the number of studies coming to some conclusion; no matter how they got
    there and whether there have been later interpretations. Science
    requires analysis--not just counting studies. Climate scientists whose
    records they analyzed have gone on record as indicating that Soon and
    Baliunas misinterpreted their studies (e.g., the article by David
    Appell in the August 2003 issue of Scientific American) and numerous
    climate scientists have indicated (see same article) that Soon and
    Baliunas misinterpreted evidence of drought or precipitation as
    evidence of temperature changes, did not use records that resolve the
    climate changes of the late 20th century, and did not take into account
    whether or not variations in different regions were coincident or not.
    Soon and Baliunas also neglect undeniable evidence of substantial
    warming of hemispheric and global surface temperatures during the past
    few decades. So the Soon and Baliunas analysis fails just about every
    meaningful criterion that might be applied to determining the validity
    of an analysis that purports to evaluate current warming in the context
    of past temperature trends. This deeply flawed study thus contrasts
    sharply with other rigorous quantitative studies (as discussed in the
    Eos article) performed by numerous other scientists with appropriate
    training in the fields of climatology and paleoclimatology, which use
    proper statistical methods for inferring past temperature changes from
    proxy data, provide uncertainty estimates, and employ appropriate
    comparisons of current and past trends.

        Question 8. What was the earth's climate like the last time that
    atmospheric concentrations of carbon dioxide were at today's levels or
    about 370 parts per million (ppm) and what were conditions like when
    concentrations were at 550 ppm, which will occur around 2060 or so?
        Response. We have to go back far into the past to find carbon
    dioxide levels approaching today's levels. Ice core studies indicate
    that modern carbon dioxide levels are unprecedented for at least four
    glacial/inter-glacial cycles: in other words, for more than 400,000
    years. Other evidence suggests that carbon dioxide levels are now
    higher than they have been for at least 10 million years. One probably
    has to go back roughly 40-50 million years ago (see chapter 3 of the
    2001 IPCC working group 1 report) to find CO2 concentrations
    were in the range of 550 ppm (i.e., roughly double their preindustrial
    concentration) and approximately 80 million years ago (i.e., the mid-
    Cretaceous period when Dinosaurs roamed the polar regions) to find
    CO2 levels in excess of 1200 ppm (a level that will be
    reached, at current rates of CO2 increase, within one to
    one-and-a-half centuries). Proxy evidence available for this period,
    tenuous though it is, suggests deep ocean temperatures 8-12+ C warmer
    than present. State of the art climate model simulations performed by
    Bette Otto-Bleisner and colleagues using the National Center for
    Atmospheric Research (NCAR) global climate model, which incorporate
    such CO2 levels (and the continental configuration
    corresponding to the mid-Cretaceous period), indicate significantly
    warmer sea surface temperatures, with tropical sea surface temperatures
    approximately 4+ C warmer and polar sea surface temperatures
    approximately 6-14+ C warmer than present. The simulations indicate an
    absence of perennial sea ice at even the most polar latitudes.

        Question 9. Are you aware of any scientists beside the authors of
    the Soon et al article who support using ``wetness'' or ``dryness'' as
    indicators of past temperatures, instead of actual temperatures or
    proxy data that reflects temperatures?
        Response. I am not aware of any other scientist who has made the
    mistake of interpreting paleoclimatic information in this way. As
    discussed above, trained paleoclimatologists typically use statistical
    methods to identify the strength of the temperature signal in a proxy
    record prior to using it in reconstructing past temperature patterns.

        Question 10. Is there any known geologic precedent for large
    increases of atmospheric CO2 without simultaneous changes in
    other components of the carbon cycle and the climate system?
        Response. There is not, to my knowledge, such an example. As
    discussed above, the geological record shows a clear relationship
    between periods of high CO2 and relatively high global mean
    temperatures. The study of the relationship between changes in CO2
    and climate in the paleoclimate record is sometimes complicated by the
    fact that these relationships can be relatively complex during rapid
    transitions between glacial and interglacial climates such as those
    that occurred with the coming and going of ice ages that occurs on a
    roughly 100 thousand year timescale over the past nearly one million
    years. However, one can turn to periods of time when the climate and
    CO2 were not varying rapidly, and thus the climate was
    approximately in an ``equilibrium'' state, for insights into the
    relationship between CO2 and climate, A perfect such example
    is the height of the last ice age, the so-called ``Last Glacial
    Maximum'' or ``LGM'' centered roughly 25 thousand years ago. At this
    time, CO2 was substantially lower than today (just below 200
    ppm) and global mean surface temperatures were several degrees (about
    4C or so) cooler than today. Such relationships between past CO2
    changes and global temperature changes typically, suggest a
    ``sensitivity'' of the climate system to enhanced CO2 of 1,
    5 to 4.5 C warming for each doubling of CO2 concentrations
    from their pre-industrial levels, similar to the range of sensitivities
    found in various climate models.

        Question 11. According to a study published in Science magazine
    recently [B. D. Santer; M. F. Wehner, T. M. L. Wigley, R. Sausen; G. A.
    Meehl, K. E. Taylor, C. Ammann, J. Arblaster, W. M. Washington, J. S.
    Boyle, and W. Bruggemann Science 2003 July 25; 301; 479-483], manmade
    emissions are partly to blame for pushing outward the boundary between
    the lower atmosphere and the upper atmosphere. How does that fit with
    the long-term climate history and what are the implications?
        Response. This is yet another independent piece of evidence
    confirming a detectable anthropogenic influence on climate during the
    late 20th century. This evidence is consistent with evidence for
    unprecedented surface warming during the past few decades--warming that
    indeed appears unprecedented for as long as we have records (i.e., for
    at least a thousand, and probably two thousand years). These changes,
    moreover, are consistent with predictions from climate models driven by
    known anthropogenic (human) forcing of the climate.

        Question 12. At this hearing, there were a number of calls for
    ``sound science.'' Could you please explain what it is about the IPCC
    process that justifies respecting the IPCC results as the very soundest
    representation of the science of climate change?
        Response. The IPCC carries out a process for developing its
    summarization of the understanding of science that leads to one of the
    most rigorously peer-reviewed scientific documents in existence,
    Individual technical chapters are prepared by expert scientific teams
    that consider the full range of published papers in a subject area.
    This expert author team then solicits an initial peer review from a
    large number of other scientists in the field, drawing on those with
    the full range of views. The reports next go through a much wider
    review that is open to literally thousands of scientists around the
    world. Finally countries, NGOs, and professional groups (such as
    business groups) are provided the opportunity to send in review
    comments. At each stage, authors consider each comment and document
    their response. The meticulousness and fairness of the revision process
    by the authors in response to reviewer comments is evaluated by an
    independent pair of ``review editors'' who are themselves top
    international climate scientists who are not authors of the report
    itself. The National Academy of Sciences, at President George W. Bush's
    request, and other national academies around the world have
    independently reviewed the process and the validity of the scientific
    findings of the IPCC and endorsed them. To question the IPCC and the
    IPCC process, as does Dr. Legates thus not only does a disservice to
    thousands of the world's top scientists; but to the exceptional care
    and rigor of the process that has led to the unanimous adoption of all
    of the IPCC's assessments by representatives of the over 150 nations
    that participate in the IPCC process. The documents are very finely
    honed and carefully phrased. The scientific studies of those such as
    or, Legates are considered, as are their review comments, and it is
    terribly disingenuous, not to mention totally unacceptable to the
    international community, after all of the care and consideration put
    into these efforts to try to so cavalierly dismiss them.
        In his testimony Legate's alleges that the IPCC report
    misrepresents what is known about climate change in past centuries and
    that it somehow replaces conventional wisdom with dramatically new
    conclusions. One must conclude that Legates either did not read the
    report, or if he did, he did not understand what he read; for if he had
    he would certainly have to recognize factually incorrect nature of his
    comments. The IPCC chapter dealing with paleoclimatic evidence
    discussed the full range of regional evidence described in the peer-
    reviewed as well as evidence from hemispheric composites that average
    the information from different regions. The paper by Soon and Baliunas
    is a dramatic throwback to the State of our knowledge many decades ago,
    while the IPCC report provides a far more upto-date assessment of all
    of the available knowledge regarding past climate change. The Soon and
    Baliunas papers provide a glaring example of the very ``unsound''
    science that Senator Inhofe claims to be concerned about, as numerous
    mainstream climate researchers have now opined in the media, and in the
    peer-reviewed scientific literature.

        Question 13. In your opinion, how do the processes used by the IPCC
    and the National Academy of Sciences compare to the process used in the
    publication of the Soon and Baliunas paper and other papers by so-
    called ``contrarians''? In the next IPCC assessment, would you expect
    that the Soon and Baliunas paper will be considered and cited, putting
    it into the context of other papers and findings and explaining why it
    has differences or similarities?
        Response. As discussed above, the IPCC is one of most rigorously
    peer-reviewed scientific documents in existence. By contrast, the
    contrarians rarely publish in the peer-reviewed literature and when
    they do, it is not uncommon to discover, as in the case of the Soon and
    Baliunas paper, irregularities in the peer-review process. Publisher
    Otto Kinne indeed indicated that the review process at Climate Research
    ``failed to detect methodological flaws'' in the Soon and Baliunas
    paper. I would indeed expect that in the next IPCC assessment, the Soon
    and Baliunas paper will be discussed and evaluated in the context of
    other available evidence and in the context of how it is faring in the
    literature when the IPCC review takes place (e.g., if there are as many
    criticisms about their work as at present, and they have not been
    seriously addressed by more careful followup studies by the authors. I
    would think their conclusions will be rejected as scientifically
    unsound. I would not presume to know in detail what the result of the
    assessment will be, but I believe it fair to assume that the rigorous
    review provided by the IPCC assessment process will not fail to
    identify the methodological flaws that appear to have slipped through
    the cracks in their publication in the journal ``Climate Research''.

        Question 14. Could you explain the IPCC's lexicon for indicating
    relative levels of confidence and how you would suggest this relates to
    the information being ``real'' and ``probable''? When IPCC says
    something is ``very likely,'' just what do they mean?
        Response. To avoid the type of misunderstanding that often results
    from when scientists seek to convey scientific results to a non-
    technical audience, the IPCC specifically sought to employ a lexicon in
    which terms such as ``likely'' or ``probable'' or ``very likely'' had
    specific statistical meanings attached to them. A fairly conservative
    standard was typically employed in this process. Consider the
    conclusion in the IPCC report that the 1990's are the warmest decade in
    at least the past 1000 years for the Northern hemisphere average
    temperature. This conclusion is based on the fact that the average
    warmth of the 1990's exceeds that for any reconstructed decade in the
    reconstructed Northern Hemisphere series. To be more specific, the
    1990's warmth exceeds any past decade by two standard errors. This
    corresponds to a roughly 97.5 percent probability based on standard
    statistical assumptions. Probabilities of 90 percent-99 percent are
    termed ``very likely'' in lexicon typically adopted by the IPCC report.
    However, this conclusion was offered as only ``likely'' (corresponding
    to a 66 percent-90 percent level of probability) rather than the more
    stringent ``very likely'' because it was based on only a small number
    of independent studies at the time. Since that time, of course, several
    more studies have affirmed this conclusion, and one might imagine that
    a more stringent conclusion will be offered in the future. This example
    nonetheless illustrates the manner by which IPCC adopted conservative
    standards in their use of terms such as ``likely'' or ``very likely''.
    It is instructive to contrast that standard with the one taken in the
    Soon and Baliunas paper. The Soon and Baliunas paper does not provide a
    quantitative estimate of any quantity (such as average Northern
    Hemisphere temperature), or any assessment of uncertainty. It is thus
    not possible for the authors to attach any meaningful statement of
    likelihood or probability to any of their conclusions. They thus
    provide no basis for judging the validity of any of the claims made in
    their paper, in striking contrast to the rigorous standards adopted by
    IPCC, and by the work of my collaborators and me.

        Question 15. In his questioning, Senator Inhofe cited results
    regarding the potential costs of implementing the Kyoto Protocol from
    the Wharton Econometric Forecasting Association (WEFA). I realize that
    you are not an economist, but would you please comment as a scientist
    on the following two points:
        (a) Senator Inhofe cited economic projections (e.g., 14 percent
    increase in medical costs; real income drop of $2,700 per household)
    going out a decade or so into the future and without any indication of
    uncertainty on these estimates implying an accuracy of two-significant
    figures. Senator Voinovich cited numbers to similar claimed accuracy
    going out 20-25 years; again without any indication of uncertainty.
    Could you please comment on what you think are the relative strengths
    and weaknesses of making climate projections based on use of physical
    laws versus economic extrapolations and what sorts of relative
    uncertainty should likely be associated with each type of estimate so
    that they can be interpreted in a comparative way by decisionmakers?
        Response. Indeed, it is somewhat remarkable that politicians who
    reject the validity, for example, of climate model simulations, which
    are based on solution of the laws of physics, can so uncritically
    accept precise economic projections based on economic forecasts based
    on untestable and unverifiable assumptions governing human
    decisionmaking, and speculative future scenarios that depend on the
    unfolding of the political process. Specific numbers of ``14 percent''
    or ``$2,700'' are of course entirely dependent on the assumptions that
    go into such forecasts. Because assumptions about future economic
    growth and about future government policies are necessarily uncertain,
    estimates of changes in costs or income from such models must also be
    quite uncertain, and so should have large uncertainties (or ranges)
    associated with them. The faith expressed in such poorly constrained
    economics estimates by the same individuals who express strong
    skepticism of results from far more physically based and testable
    climate simulation models, strikes me as a remarkable inconsistency.
        (b) Because you may be familiar with the 1997 study by the World
    Resources Institute entitled ``The costs of climate protection: A guide
    for the perplexed,'' which explains the important role of assumptions
    in leading to very different cost estimates from even one economic
    model, much less among different models, could you explain in a
    comparative fashion how robust the findings regarding the ``hockey
    stick'' behavior of the climate in the various studies carried out: by
    you and fellow investigators may be to variations in the assumptions
    made. It's clear that varying the assumptions among reasonable
    possibilities in the economic models can change what is calculated to
    be a few percent impact on the economy to a small gain; would changes
    in the assumptions you are making change the indication of strong
    anthropogenic warming to an indication of human-induced cooling?
        Response. The millennial temperature reconstruction (or ``hockey
    stick'' as it was termed by former GFDL head Dr. Jerry Mahlman) is
    based on a rigorously validated statistical model with demonstrated
    predictive skill based on comparisons with independent data. The
    primary conclusions drawn from the reconstruction (e.g. the anomalous
    nature of late 20th century warmth) are based on a conservative
    appraisal of the uncertainties in the reconstruction, and are not
    strongly dependent on the assumptions made. The same--conclusions have
    been affirmed now by several other independent empirical and-model-
    based estimates. As discussed above, this contrasts with economic
    predictions which are necessarily far more sensitive to the assumptions
    that go into them.

        Question 16. In his opening statement, Senator Inhofe concluded
    that the Soon and Baliunas paper is ``credible; well-documented; and
    scientifically defensible.'' By contrast, your testimony indicated that
    the experts in the field do not consider this to be the case. Does one
    have to be an expert in the field to understand the apparent problems
    with this paper? If not, could you summarize in terms for non-
    scientists what the key problems with the paper are?
        Response. The mainstream scientific research community has indeed
    rejected the approach, interpretation, and conclusions advanced by Soon
    and Baliunas as fundamentally unsound. The major flaws in the analysis,
    as described in earlier comments in more detail, are basic enough that
    they can be understood by a non-specialist. In short, the analysis by
    Soon and Baliunas is unsound because (a) they inappropriately
    interpreted indicators of past precipitation as evidence of past
    temperature changes, (b) they did not use an approach which takes into
    account the simultaneity and lack of simultaneity of variations in
    different regions, and (c) they did not employ a proper standard for
    evaluating recent changes (i.e., changes during the past few decades)
    in the context of past variations. Indeed, they also misinterpreted
    past published work, and did not provide any quantitative estimates,
    let alone estimates of uncertainty. It is difficult to find anything of
    scientific merit at all in their published work.

        Question 17. As I understand it, the data that both you and Soon
    and Baliunas draw from is the same, and it is not a question of the
    data being the problem. Instead, it is apparently the processing of the
    data that you are indicating has been done in a substandard way by Soon
    and Baliunas. Is this correct?
        Response. Keep in mind that Soon and Baliunas, unlike my
    collaborators and I, don't actually analyze any data at all. They
    simply claim to have `interpreted' past studies (often incorrectly).
    Soon and Baliunas refer to a number of proxy data studies that describe
    data which we employed in our analysis. There are also many proxy data
    that we used in our study that the Soon and Baliunas do not discuss.
    However, as alluded to in the question, the real issue isn't what data
    were used. Numerous independent now-published studies employing widely
    different assemblages of proxy climate data sets have demonstrated
    (e.g, as in the Eos article discussed earlier) a similar pattern of
    past variations in hemispheric mean temperature. The real issue with
    Soon and Baliunas is indeed not the set of studies that they claim to
    have interpreted, but rather the approach that they took to
    interpreting those studies. As indicated in previous comments, Soon and
    Baliunas, unlike mainstream climate researchers, did not employ a
    method for isolating the actual temperature signal in the proxy records
    before using the records to draw conclusions regarding past temperature
    changes. Unlike mainstream researchers, they did not aggregate
    information in a way that addresses whether or not variations in
    different regions are simultaneous. Unlike mainstream researchers, they
    did not analyze the actual modern (late 20th century) warmth in the
    context of past variations. And finally, they did not even produce a
    quantitative estimate of past temperature variations, let alone an
    estimate of uncertainty.

        Question 18. The Soon et al literature review has been described as
    shifting the paradigm away from the ``hockey stick'' description of
    global warming. It seems that that review simply attempted to revive an
    older theory of climate change that has been discarded by NOAA, the
    USGCRP, the NAS, the IPCC, etc. Please comment.
        Response. The mainstream scientific community has clearly and
    decisively rejected the Soon and Baliunas papers as scientifically
    unsound which undermines any claims made by industry-funded special
    interest groups or politicians, that the papers provide any valid
    scientific conclusions, let alone the basis for a shift of the
    ``paradigm''. Indeed, the Soon and Baliunas papers simply promote a
    number of long-discredited myths which have been replaced, in recent
    decades by far more rigorous and quantitative analyses as described by
    the IPCC, USGCRP, NAS, and other mainstream scientific organizations
    and funding agencies. In short, the Soon & Baliunas papers simply
    repackage myths that were discredited more than a decade ago.

        Question 19. In an opinion-editorial by former Secretary of Energy
    James Schlesinger, he suggested that ``we have only a limited grasp of
    the overall forces at work, . . .'' in terms of global climate change.
    Could you please summarize for us what the scientific community
    considers the key forces at work over the past 1000 years, how well
    these estimates are understood, and whether there is a general
    consistency or inconsistency between the various forcings and the
    climate estimates that you and colleagues have developed for the last
    1000 years?
        Response. Mr. Schlesinger's assertions entirely mischaracterize the
    nature of our scientific knowledge, which has advanced tremendously
    during the past several decades. In fact, a very large number of peer-
    reviewed scientific studies have been published in the leading
    scientific, journals such as Nature and Science in the past two decades
    elucidating the role of natural and anthropogenic factors in observed
    climate changes. Physically based models have been developed and
    validated against observations, and these models reproduce complex
    climate phenomena such as El Nino. These same models have been driven
    with the primary ``external'' factors that are believed to govern
    climate variations on timescales of decades and centuries. These
    external factors include natural factors, such as the modest estimated
    variations in radiative output of the Sun, which varies by a fraction
    of a percent over time, variations in the frequency and intensity of
    explosive volcanic eruptions, which have a several-year cooling effect
    on the climate through the injection of reflective volcanic aerosols
    into the stratosphere, and very small changes in the Earth's orbit
    relative to the Sun that occur on multi-century timescales. These
    external factors also include the ``anthropogenic'' influences of
    increased greenhouse gas concentrations due to fossil fuel burning,
    changes in the reflective properties of the land surface due to human
    land use alterations, and the regional cooling effect of anthropogenic
    sulphate aerosols in certain industrial regions. When driven with these
    factors, these climate models have demonstrated a striking ability to
    reproduce observed global and hemispheric temperature trends during the
    20th century, as well as longer-term trends in past centuries as
    reconstructed from proxy data. Such results are nicely summarized in
    the 2001 IPCC scientific working group report. Mr. Schlesinger would
    have benefited from a reading of this report, or the follow-up National
    Academy of Sciences report that endorsed the key IPCC conclusions,
    prior to writing his oped piece, which reflects a decades-old
    understanding of the State of the science.

        Question 20. In Dr. Soon's testimony, he speaks about there being
    ``warming'' and ``cooling'' for different periods. If he did not
    construct an integral across the hemisphere or a real timeline; can he
    say anything other than that there were some warm periods and cool
    periods?
        Response. Aside from not adequately distinguishing temperature
    changes from hydrological changes, Dr. Soon and his collaborators
    indeed did not even attempt to estimate contemporaneous patterns of
    past temperature change, let alone an integral across the hemispheric
    domain to assess hemispheric mean temperature changes. It is unclear
    what, if any, meaningful conclusions can be drawn from the Soon and
    Baliunas study.

        Question 21. Dr. Soon indicates that ``local and regional, rather
    than global average changes are the most relevant and practical measure
    of climate change and its impact.'' Could you please comment on this,
    including the relative likelihood of identifying a signal of climate
    change amidst the local fluctuations? In what sense might local changes
    be the most practical measure? In that the primary forcings of the
    climate are global in scale, does it not make most sense to first
    determine how the large-scale rather than the regional climate might be
    affected?
        Response. Dr. Soon's comments are truly misguided. Firstly, the
    surface temperature reconstructions published by my colleagues and I
    explicitly resolve regional patterns of surface temperature, so it is
    entirely unclear why Dr. Soon believes that we don't address regional
    climate changes. Had Dr. Soon understood our papers, he would be aware
    that we do. However, unlike the study that Dr. Soon published, our
    reconstructions explicitly take into account the issue of the relative
    timing and simultaneity of surface temperature changes in different
    regions. Only through doing this it possible to form an integrated
    measure of temperature changes such as hemispheric mean temperature.
    Scientists with training in climatology, statistics; and other areas of
    research required in the study of paleoclimate reconstruction know that
    the signal-to-noise ratio of any surface response to global radiative
    climate forcing increases as the scale of spatial averaging increases,
    In discussions of climate change it is thus the integral of the surface
    temperature field over an entire hemisphere or globe, which constitutes
    the most useful single variable for detecting, and attributing causal
    factors to observed changes. The spatial signature of the surface
    temperature signal (both with respect to position on the surface of the
    Earth, and altitude in the atmosphere) can nonetheless help to
    distinguish one source of climate forcing (e.g. solar) from another
    (e.g. enhanced greenhouse gases). My colleagues and I have indeed used
    the spatial patterns of surface temperature changes in past centuries
    to identify the role of natural external forcing of climate [Shindell,
    D.T., Schmidt, G.A., Mann, M.E, Rind, D., Waple, A., Solar forcing of
    regional climate change during the Maunder Minimum, Science, 294, 2149-
    2152, 2001; Waple, A., Mann, M.E., Bradley, R.S., Long-term Patterns of
    Solar Irradiance Forcing in Model Experiments and Proxy-based Surface
    Temperature Reconstructions, Climate Dynamics, 18, 563-578, 2002;
    Shindell, D.T., Schmidt, G.A., Miller, R., Mann, M.E., Volcanic and
    Solar forcing of Climate Change During the Pre-Industrial era, Journal
    of Climate, in press, 2003]. Both Dr. Soon and Dr. Legates advocate in
    their testimony a primary role of solar forcing in recent climate
    change, though they provide no quantitative justification for this
    assertion at all. In fact, nearly a dozen detailed ``detection'' and
    ``attribution'' studies published during the past decade by leading
    climate researchers in the premier international scientific peer-
    reviewed journals such as Science and Nature, have shown that the
    vertical and horizontal pattern of observed warming is inconsistent
    with the response of the climate to solar forcing, but is consistent,
    with the response of the climate to anthropogenic forcing. Thus a
    prudent use of spatial information, as described in various studies by
    leading climatologists, including my collaborators and I, can
    potentially help elucidate the roles of natural and anthropogenic
    factors. However, Dr. Soon's studies are deficient in their use of any
    such information, and provide no insights into the factors governing
    past climate change.

        Question 22. This year, the western United States is anomalously
    hot and dry. The eastern United States is wetter than it has been since
    approximately 1891 and cool. Europe is hotter and drier than it has
    been in about 150 years. If we assume for the moment that these types
    of anomalies would persist for 50 years, are these the types of
    anomalies that Soon and Baliunas would consider as being indicative of
    there being an equivalent to the Medieval Warming in the western United
    States and Europe while at the same time there is the equivalent of the
    Little Ice Age in eastern North America? How would your type of
    approach vary in its analysis of the year 2003 compared to the
    apparently contradictory results that Soon and Baliunas would have?
        Response. Indeed, as my colleagues and I discussed in our peer-
    reviewed articles in ``Eos'' and more recently ``Geophysical Research
    Letters'' [Mann, M.E., Jones, P.D., Global Surface Temperatures over
    the Past two Millennia, Geophysical Research Letters, 30 (15), 1820,
    doi: 10.1029/2003GL017814, 2003] the Soon and Baliunas approach is
    indeed internally contradictory in that it would separately identify
    anomalies for even a given year, such as 2003, as simultaneously
    supportive of conditions they would classify as associated with a
    ``Little Ice Age'' and a ``Medieval Warm Period'' anomaly. As outlined
    in the question, this year's pattern of climate anomalies is a perfect
    example. Trained climatologists and paleoclimatologists know that one
    must independently evaluate precipitation or drought information from
    temperature information in reconstructing past climate patterns. For
    example, colleagues of mine and I have developed reconstructions of
    patterns of drought over the continental U.S. in past centuries from
    droughtsensitive tree-ring data [Cook, E.R., D.M. Meko, D.W. Stahle,
    and M.K. Cleaveland, Drought Reconstructions for the Continental United
    States, Journal of Climate, 12, 1145-1162, 1999; Zhang, Z., Mann, M.E.,
    Cook, E.R., Alternative Methods of Proxy-Based Climate Field
    Reconstruction: Application to the Reconstruction of Summer Drought
    Over the Conterminous United States back to 1700 From Drought-Sensitive
    Tree Ring Data, Holocene, in press, 2003]. The drought reconstructions
    display a quite different pattern of behavior over time from
    reconstructions of Northern Hemisphere mean temperatures, just as
    patterns of drought over the continental U.S. during the 20th century
    as recorded from instrumental data show relatively little in common
    with instrumental Northern Hemisphere mean temperature estimates (for
    example, the most prominent drought episode was the `dust bowl' of the
    1930's, while the most prominent anomaly in the Northern Hemisphere
    temperature record is the late 20th century warming). Drought and
    temperature are essentially independent climate variables. The papers
    by Soon and Baliunas seem not to recognize this fundamental fact.
    Finally, there is an irony in the testimonies of Soon and Legates in
    that they seem to be criticizing my colleagues and me for supposedly
    only focusing on the reconstruction of temperature patterns, when in
    fact we, and not they, have published work reconstructing past patterns
    of drought, precipitation, and atmospheric circulation from proxy
    climate data. However, we have made careful use of the information
    contained in proxy data in independently reconstructing patterns of
    temperature and patterns of drought. By contrast, Soon and colleagues
    hopelessly convolute such information in their interpretations of past
    climate trends.

        Question 23. Could you provide a more detailed explanation for the
    apparent Northern Hemisphere, cooling from the 1940's to 1970's? What
    is the general expectation of what would have happened to the climate
    in the absence of any human influences, so just continuing on from the
    trend for the last 1000 years prior to human intervention?
        Response. In fact, this issue has been studied by quite a number of
    climate scientists for well over a decade. As I mentioned in my
    testimony, a statistically significant cooling trend from 1940's to the
    1970's is not evident for the globe, but only, for the Northern
    Hemisphere. Dr Legates testimony on this matter is incorrect in that
    regard. The observed record of global-mean temperature changes over the
    past 100 years indicates a warming to about 1940; little change from
    1940 to the mid-1970's, and then further warming, Legates implies in
    his comments that these changes are inconsistent with our current
    understanding of the factors governing climate change. This is also
    incorrect. In order to understand these observed changes it is
    necessary to consider all likely causal factors, both anthropogenic and
    natural, Anthropogenic factors include the warming effects of
    greenhouse gases and the cooling effects of sulfate aerosols. Natural
    factors include changes. in the output of the Sun and the effects of
    explosive volcanic eruptions (such as the El Chichon eruption in 1982
    and the Mt. Pinatubo eruption in 1991). and internal variability
    associated with natural climate oscillations in the ocean circulation
    and various modes of coupled ocean-atmosphere variability (such as El
    Nino). When all of these factors are considered, models give an
    expected pattern of 20th century temperature changes that is in
    remarkable agreement with the observations--and the models clearly show
    the three phases noted above. In particular, the leveling off of the
    warming trend over 1940-1975 turns out to be explained largely by the
    relatively rapid increase in cooling effects of sulfate aerosols as the
    world emerged from the Depression and WWII (and perhaps a small
    contribution from natural, internal variations in ocean currents). This
    cooling temporarily offset the warming due to increasing concentrations
    of greenhouse gases. This was first pointed out in a paper by Dr. Tom
    Wigley of the National Center for Atmospheric Research (NCAR) in Nature
    in 1989 and has been verified by numerous additional studies since.
    This agreement between models and observations shows quite clearly that
    human factors have been the dominant cause of global-scale climate
    change over the past 50 years, contrary to the repeated assertions by
    Soon and Legates that they are a manifestation of natural climate
    variability. In the absence of anthropogenic factors, model simulations
    indicate that natural factors alone would have lead to a slight cooling
    trend of global temperatures over the 20th century [Crowley, T.J.,
    Causes of Climate Change Over the Past 1000 Years, Science, 289, 270-
    277, 2000], in stark contrast to the dramatic warming that has been
    observed.

        Question 24. It was suggested at the hearing that increased
    CO2 could enhance plant life, and that since plants produce
    oxygen, this could lead to more O2 and less CO2.
    Could you please comment on the likelihood of this and how large the
    percentage changes could possibly be, recognizing that as the CO2
    decreased, this would presumably mean the plants would do less well and
    conditions would cool?
        Response. Those suggestions (for example, Legates testimony with
    regard to the role of the `CO2 fertilization' effect)
    represent a misunderstanding of the factors governing carbon cycle
    dynamics and their interaction with climate. In fact, careful studies
    that have been performed with coupled climate/terrestrial carbon cycle
    models that take into account the internal coupled interactions between
    climate and carbon dioxide, accounting for multiple potential factors
    such as (a) the potential `CO2 fertilization' effect in
    which productivity of plants increases in a higher CO2
    environment, (b) the impact of climate on productivity in which higher
    surface temperatures favor enhanced plant growth, and (c) the feedback
    of CO2 back on surface temperature alluded to in the
    question [see chapter 3 of the 2001 IPCC working group 1 report]. Such
    studies show that changes in surface temperature, through their impact
    on biological productivity, have led to, at most, changes of 5 to 10
    ppm in CO2--levels over the past 1000 years [see Gerber, S,
    Joos, F., Bruegger, P.P., Stocker, T.F., Mann, M.E.; Sitch, S.,
    Constraining Temperature Variations over the last Millennium by
    Comparing Simulated and Observed Atmospheric CO2; Climate
    Dynamics, 20, 281-299,2003]. Such changes are minimal in comparison
    with the dramatic increases in CO2 concentrations of more
    than 80 ppm associated with human activity, suggesting that the
    `CO2 fertilization' effect advanced by Legates in his
    testimony in reality has a minimal role, at best, in the modern changes
    taking place in CO2 concentrations and climate.

        Question 25. Could you please clarify your remarks regarding the
    FACE experiments? When you say that increased CO2 leads to
    more uptake and that they will rot, do you mean that all plants will
    grow and eventually die and decay, and that increased CO2
    really only ties up a bit more carbon in the process?
        Response. The sequence of questions and time allotted did not allow
    me to adequately explain this basic, but important point. The point I
    was making in my testimony is that the supposed increase in the
    terrestrial carbon reservoir due to enhanced plant growth that is
    argued to occur in a higher CO2 concentration atmosphere
    (the so-called `CO2 fertilization' effect) is not a long-
    term, sustained effect, It is only a short-term effect that lasts only
    over the generational timescales of forest stands. Any depletion of the
    atmospheric carbon reservoir due to enhanced growth or productivity of
    plants argued to arise from higher CO2 concentrations is
    short lived, because the plant or tree eventually dies and gives its
    carbon back to the atmosphere either through microbial activity
    (rotting) or burning. In other words, when plants, with any potential
    additional organic carbon storage that might arise from enhanced
    biological activity eventually die, they don't simply pile up in place
    with their carbon reservoir intact (which is what is implicitly assumed
    by those who argue that `CO2 fertilization' represents a
    potential long-term offset to anthropogenic CO2 increases).
        Instead, this carbon is acted upon by biological, chemical, or
    physical processes which serve to add the carbon back to the
    atmosphere. Thus, the so-called ``CO2 fertilization''
    effect, cannot serve as a permanent offset to anthropogenic increases
    in the atmospheric carbon budget (i.e., atmospheric CO2
    concentrations), as implied by Legates in his testimony. It may simply
    act to slow, slightly, the rate of CO2 increase in the
    atmosphere by slightly increasing the storage rate (but not the
    residence time) of carbon in the terrestrial biosphere.
        Another way to estimate the potential influence is by considering
    the total amounts of carbon presently stored in vegetation. Present,
    about 600 billion tons of carbon are tied up in the aboveground
    vegetation. About 2-3 times this much is tied up in roots and below
    ground carbon, which is a more difficult carbon pool to augment. By
    comparison, scenarios for fossil fuel emissions for the 21st century
    range from about 600 billion tons (if we can keep total global
    emissions at current levels, which implies controls well beyond the
    Kyoto Protocol calls for) to over 2500 billion tons if the world
    increases its reliance on combustion of coal as economic growth and
    population increase dramatically. These numbers clearly indicate that
    sequestering a significant fraction of projected emissions in
    vegetation is likely to be very difficult, especially as forests are
    cleared to make way for agriculture and communities. While there are
    possibilities of storage in wells and deep in the ocean, stabilizing
    the atmospheric CO2 concentration would require gathering up
    the equivalent of 1 to 2 times the world's existing above ground
    vegetation and putting it down abandoned oil wells or deep in the
    ocean. While CO2 fertilization will help to increase above
    ground vegetation a bit, storing more than a few tens of percent of the
    existing carbon would be quite surprising, and this is likely to be
    more like a few percent of global carbon emissions projected for the
    21st century.

        Question 26. Senator Thomas stated that ``[t)he rise in temperature
    during the 20th century occurred between 1900 and 1940.'' Could you
    please provide an indication of how much change occurred during this
    period based on internationally accepted observations, and compare this
    to the total change during the 20th century? Also please comment on
    whether it is scientifically representative to calculate a change
    starting with a cold period due to volcanic eruptions and end it during
    a period devoid of volcanic eruptions and then compare it to the
    century long period, which had major volcanic eruptions in both the
    first and last decades of the century.
        Response. A cursory review of the actual evidence (see e.g. Figure
    2.1 of chapter 2 of the 2001 IPCC Scientific Working Group report)
    indicates the following approximate attributes in the observed record
    of global-mean temperature changes over the past 100 years: a warming
    of approximately 0.3+ C to 1940, a statistically insignificant change
    (given the uncertainties) from 1940 to the mid-1970's, and then an
    additional warming of approximately 0.5+ C from 1970 to 2000. Senator
    Thomas' claim is thus clearly mistaken. As discussed in my answer to an
    earlier question, this pattern of behavior is reproduced closely by
    models driven with estimates of both natural and anthropogenic forcing
    of the climate during the 20th century. The period of relative stasis
    in global mean temperatures from 1940 to 1970, in these model
    simulations, appears to result from the cooling impact of anthropogenic
    aerosols (for which there was a large increase during that time period)
    as well as a cooling contribution from explosive volcanic eruptions
    that occurred during that period, which tended to offset the warming
    influence of increased greenhouse gas concentrations during that time
    period. However, much of the overall warming of the globe during the
    20th century (which is between 0.6+ C and 1.0+ C depending on the
    precise instrumental data set used, and the precise endpoints of the
    interval examined) is clearly a result of increased greenhouse gas
    concentrations, as established in these simulations.

        Question 27. Senator Thomas stated that ``there is no real
    evidence'' that the greenhouse gases are affecting the climate. Could
    you please summarize the available evidence explaining their probable
    effect? Please include in your answer a specific example of a proxy
    indicator such as tree rings and explain the various subtleties in
    deriving a temperature.
        Response. As discussed in my answers to previous questions, the
    fact that increased greenhouse gas concentrations have a role in 20th
    century warming is no longer considered as being in doubt by mainstream
    researchers. Even noted contrarians such as Patrick Michaels of the
    Cato Institute now agree with this conclusion. The only room for
    legitimate scientific debate concerns the relative role of greenhouse
    gas concentrations vs. other factors, and the rate of future warming
    that may occur. Evidence establishing the role of anthropogenic
    greenhouse gas increases in 20th, century warming includes the
    agreement with the full spatial (horizontal and vertical) pattern of
    warming with predictions from model simulations, and the fact that only
    model simulations which include anthropogenic forcing can match the
    observations, as discussed earlier. Evidence for an anthropogenic
    influence on climate also comes from evidence of the anomalous nature
    of late 20th century warmth in a very long-term context (i.e., in at
    least the past millennium, and potentially the past several millennia
    or longer). One such source of evidence for this conclusion comes from
    proxy climate records (such as tree rings, corals, and ice cores) that
    can be used to reconstruct long-term temperature patterns based on a
    careful consideration of the temperature signal in those data, as
    discussed in my response to earlier questions. But other evidence of
    anomalous late 20th century warmth comes from indications of
    unprecedented melting of mountain glaciers the world over (including
    meltback in the Alps so dramatic that it recently revealed the now-
    famous ``Ice Man'' who had been trapped in ice for more than 5000
    years), and evidence of unusual phenological changes (e.g. the timing
    of flowering of plants) during the late 20th century.

        Question 28. Senator Carper asked the other two witnesses if they
    thought it ``possible to emit unlimited amounts of CO2 into
    our atmosphere without having any impact on climate or temperature?''
    What is your expectation of what would occur? That is, how much change
    in the CO2 concentration would cause how much of a response?
        Response. The response of global mean surface temperature to
    increased CO2 varies roughly as the logarithm of the
    CO2 concentration (meaning that increments in temperature
    scale with the percentage change in CO2 rather than the
    change in amount itself). This is a very well known, and long
    established result that follows both from basic theoretical
    considerations of radiative transfer theory, and is embodied in
    experiments using global climate models with varying levels of CO2
    concentrations. The statistical relationship between estimated
    concentrations of CO2 and the admittedly crude estimates of
    global mean temperatures at various periods in the geological past or
    during past glacial intervals, conform relatively well to this
    theoretical relationship within estimated uncertainties [see e.g. the
    textbook, ``Earth's Climate Past and Future'', by W.F. Ruddiman (WR
    Freeman and Co), 2001]. I was extremely surprised when Dr. Soon
    indicated that he did not know how to answer Senator Carper's question,
    suggesting that he is not familiar with this fairly basic scientific
    knowledge.
        This result implies, in the absence of any other factors, a linear
    increase in temperature over time in response to an exponential
    increase in CO2 (which is not a bad description of the
    character of the CO2 trend associated with exponentially
    increasing anthropogenic activity over the past two centuries). Climate
    models tell us that the ``slope'' of that linear increase is between
    1.5+ C to 4.5+ C for each doubling of the CO2 concentration.
    In this context, the testimony Dr. Legates that an arbitrary increase
    in greenhouse gases would lead only to a ``slight'' increase in
    termperature, seems especially disingenuous. Dr. Legates seems to be
    suggesting that the warming would be small despite the magnitude of the
    CO2 increase. Yet, both model-based studies and analyses of
    how climates changes in the past may have been influenced by changes in
    atmospheric composition suggest that a 1.5+ C to 4.5+ C increase in
    temperature is likely for each doubling of the CO2
    concentration. Thus, a quadrupling of the CO2 concentration,
    which is plausible if the world chooses to derive most of its future
    energy from coal, would be expected to be associated with a roughly 3+
    C to 9+ C increase in global mean temperature. Does Dr, Legates
    consider this a ``slightly'' increased temperature?

        Question 29. In his testimony, Dr. Legates indicated that there
    were historical cases where the temperature has gone up; but the
    CO2 has fallen. Do you agree there were such periods and how
    would you explain this?
        Response. It is certainly the case that this has happened in the
    past. However, it is hardly surprising, and certainly not inconsistent
    with our established understanding of the various factors that
    influence surface temperatures. The warming response to increased
    greenhouse gas concentrations lags the actual increase in greenhouse
    gas concentrations in the atmosphere potentially by several decades,
    due to the sluggish response of the oceans, which have an enormous
    thermal capacity compared to the atmosphere, to increased surface
    radiative forcing. So warming is not expected to be contemporaneous
    with changes in CO2, but instead, to lag it by several
    decades. In addition, greenhouse gases are certainly not the only
    factor affecting the average surface temperature of the Earth. There
    are other anthropogenic factors, such as increased sulphate aerosols,
    which can have a cooling effect on the climate, and natural factors,
    such as volcanic activity, modest natural variations in solar output,
    and internal dynamics associated with climate events such as El Nino,
    which also influence the average surface temperature of the globe. At
    any particular time, these other factors may outweigh the warming
    effect due to increased greenhouse gases. For example, the relative
    lack of warming during the period 1940-1970 appears to be related to a
    combination of such factors, as discussed in my response to an earlier
    question. But while these other factors tend to cancel over time, the
    increased greenhouse gases lead to a systematic warming that will not
    cancel out over time. It is for precisely this reason that late 20th
    century warming now appears to have risen above the range of the
    natural variability of past centuries.
        There are two myths commonly perpetuated by climate change
    contrarians with regard to the relationship between historical CO2
    and temperature variations that are worth addressing in particular:
        (1) Contrarians sometimes argue that the fact that the seasonal
    cycle in atmospheric CO2, which is opposite of the seasonal
    cycle in temperature in the Northern Hemisphere (maximum atmospheric
    CO2 levels over the course of the year occur during the
    Northern Hemisphere winter) implies a negative feedback of temperature
    on CO2 concentration. Such an argument is based on a most
    profound misunderstanding of the basic principles governing atmospheric
    chemistry. Properly trained atmospheric chemists know that the seasonal
    cycle in global atmospheric CO2 concentration is governed by
    the breathing of the terrestrial biosphere, which exhibits a
    hemispheric (and thus seasonal) asymmetry: there is a net uptake of
    atmospheric CO2 (and thus a drawdown of atmospheric CO2
    concentrations) by terrestrial plants during the Northern Hemisphere
    summer growing season, owing to the vastly greater proportion of land
    in the Northern Hemisphere. This simple fact, and nothing else,
    dictates the relationship between Northern Hemisphere surface
    temperatures and CO2 concentrations on seasonal timescales.
        (2) Contrarians sometimes argue that the relationship between
    atmospheric CO2 concentrations and temperature variations
    associated with glacial/interglacial variations over the past several
    hundred thousand years, as deduced from ice core measurements shows
    that CO2 is an effect, rather than cause, of climate
    variability. This reasoning is unsound for at least two fundamental
    reasons:
        (a) Detailed measurements show that global atmospheric CO2
    concentrations lead estimated polar temperature variations (as deduced
    from ice core oxygen isotope ratios) during the long phase of increased
    glaciation, consistent with greenhouse gas forcing of the atmosphere.
    There is some evidence that CO2 concentrations, however, lag
    estimated polar temperature variations during the rapid phase of
    deglaciation (melting of the terrestrial ice sheets at the termination
    of an ice age). This observation is the basis of the flawed argument
    summarized below. During this more rapid `deglacial' phase, the climate
    system if far from being in an equilibrium state, and the dynamics of
    the climate system must be considered as representative of the a
    coupled interaction between surface temperature, atmospheric
    CO2, ocean circulation, and glacial mass. It is well known
    by glaciologists who study this problem that the relationship between
    CO2 and temperatures in such a scenario cannot be
    interpreted in terms of a simple causeeffect relationship.
        (b) Even during the rapid deglaciation, the oxygen isotopes from
    the ice cores only provide an estimate of surface temperature
    variations in the proximity of the ice core (and a very imperfect one,
    owing to possible seasonal deposition biases and non-temperature
    influences on isotope fractionation). They certainly do not provide an
    estimate of hemispheric, let alone global, temperature variations.
    Thus, a comparison of ice core estimates of CO2 and oxygen
    o18 ratios cannot be used to confidently infer the relationship between
    CO2 concentrations and global mean temperatures

        Question 30. During the hearing, there was some contention over the
    issue of the effect of surface cover changes and urban influences on
    the climate? Could you please restate your position on the likely sign
    and magnitude of the influence of both factors?
        Response. Unfortunately misleading comments by Soon and Legates,
    and the complexity of the issues involved, made it difficult for me to
    convey, in the brief time allotted, the established science dealing
    with the various influences on Earth's surface radiation balance and
    changes therein in recent decades. Legates in his testimony confused
    and misstated the nature of both natural and anthropogenic influences
    on the Earth's surface energy budget and on the measurement of surface
    temperatures from surface-based stations. There are several different
    issues involved here, which I will attempt to clarify one at a time
    below:
        (1) The claim made by Legates that the location of thermometer
    measurements in urban centers biases estimates of global mean
    temperature from the available meteorological observations would be
    correct were this effect not already carefully accounted for. In
    particular, possible urban heat island effects on global temperature
    estimates have been studiously accounted for in estimates that have
    been produced for more than a decade, See e.g. the 2001 IPCC report.
    This is unrelated to the issue of the influence of land-use changes on
    the surface radiation budget, though Legates testimony blurs the
    distinction between the two issues:
        (2) The implication by Legates that land-use changes (such as
    urbanization) are the dominant influence on changes in the absorptive
    properties of the Earth as a whole in recent decades is completely
    wrong for at least two reasons:
        (a) The primary factor impacting changes in the absorption of solar
    insolation by the Earth's surface in modern decades is the decrease in
    reflective snow and ice cover due to the warming of the Earth's
    surface. This represents a well-known positive feedback (the `ice-
    albedo' feedback) associated with global warming in which warming leads
    to melting of snow and ice, which decreases the reflective properties
    of the surface, increasing surface absorption of radiation, and: thus
    increased the surface temperatures themselves. This crucial positive
    feedback, which enhances the impact of greenhouse gas concentrations on
    the warming of the surface, is fully accounted for in the climate model
    simulations that I have referred to above and in my testimony.
        (b) While urbanization, as suggested by Legates, may lead to
    increased absorption of solar insolation in some urban areas, this is
    the more minor of the human land use changes impacting climate. There
    are far more extensive regions of the Earth where other changes in land
    use, such as conversion of forested land to agricultural land, have,
    instead, increased the reflective properties of the Earth's surface
    [Ramankutty, N., and J. A. Foley Estimating historical changes in
    global land cover: croplands from 1700 to 992, Global Biogeochemical
    Cycles, 13, 997-1027, 1999.], tending to cool the surface, as I
    explained in my testimony. Scientists who have studied the influences
    of these effects have found that the latter cooling effect is the
    dominant of these two anthropogenic land-use influences on the Earth's
    surface properties. Thus, climate model simulations investigating the
    influence of land-use changes on hemispheric or global mean
    temperatures indicate that they have imposed a modest cooling influence
    [Govindasamy, B., P.B. Duffy, and K. Caldeira, Land use changes and
    Northern Hemisphere cooling, Geophysical Research Letters, 28, 291-294,
    2001; Bauer, E, M. Claussen, and V. Brovkin, Assessing climate forcings
    of the Earth system for the past millennium, Geophys. Res. Lett., 30,
    doi: 10.1029/2002GL016639, 2003] that partially offsets even greater
    warming that would have been realized during the 20th century due to
    anthropogenic greenhouse gas influences, Evidence, therefore, does not
    support the case, as argued by Legates, that the full range of human
    land use changes have had a net warming effect on the climate. They
    have had a modest cooling influence on the climate.

        Question 31. Do you receive any income from any sources which have
    taken advocacy positions with respect to the Kyoto Protocol, the U.N.
    Framework Convention on Climate Change, or legislation before the U.S.
    Congress that would affect greenhouse gas emissions? If so, please
    identify those sources and the relevant advocacy position taken.
        Response. I do not, nor have I ever, received any such income.
                                   __________

    Statement of David R. Legates, Director, Center for Climatic Research,
                             University of Delaware

        Distinguished Senators, panelists, and members of the audience: I
    would like to thank the Committee for inviting my commentary on this
    important topic of climate history and its implications. My name is
    David R. Legates and I am an Associate Professor and Director of the
    Center for Climatic Research at the University of Delaware in Newark,
    Delaware. My research interests have focused on hydroclimatology--the
    study of water in the atmosphere and on the land--and on the
    application of statistical methods in climatological research.
        I am familiar with the testimony presented here by Dr. Soon. I
    agree with his statements and I will not reiterate his arguments. My
    contributions to Dr. Soon's research stemmed from my grappling with the
    apparent technology between the long-standing historical record and the
    time-series recently presented by Dr. Mann and his colleagues. It also
    stems from my own experiences in compiling and merging global estimates
    of air temperature and precipitation from a variety of disparate
    sources.
        My Ph.D. dissertation resulted in the compilation of high-
    resolution climatologies of global air temperature and precipitation.
    From that experience, I have become acutely aware of the issues
    associated with merging data from a variety of sources and containing
    various biases and uncertainties. By its very nature, climatological
    data exhibit a number of spatial and temporal biases that must be taken
    into account. Instrumental records exist only for the last century or
    so and thus proxy records can only be used to glean information about
    the climate for earlier time periods. But it must be noted that proxy
    records are not observations and strong caveats must be considered when
    they are used. It too must be noted that observational data are not
    without bias either.

                  THE HISTORICAL RECORD OF THE LAST MILLENNIUM

        Much research has described both the written and oral histories of
    the climate as well as the proxy climate records (e.g., ice cores, tree
    rings, and sedimentations) that have been derived for the last
    millennium. It is recognized that such records are not without their
    biases--for example, historical accounts often are tainted with the
    preconceived beliefs and limited experiences of explorers and
    historians while trees and vegetation respond not just to air
    temperature fluctuations, but to the entire hydrologic cycle of water
    supply (precipitation) and demand (which is, in part, driven by air
    temperature). Nevertheless, such accounts indicate that the climate of
    the last millennium has been characterized by considerable variability
    and that extended periods of cold and warmth existed. It has been
    generally agreed that during the early periods of the last millennium,
    air temperatures were warmer and that temperatures became cooler toward
    the middle of the millennium. This gave rise to the terms the
    ``Medieval Warm Period'' and the ``Little Ice Age'', respectively.
    However, as these periods were not always consistently warm or cold nor
    were the extremes geographically commensurate in time, such terms must
    be used with care.

         A BIASED RECORD PRESENTED BY THE IPCC AND NATIONAL ASSESSMENT

        In a change from its earlier report, however, the Third Assessment
    Report of the Intergovernmental Panel on Climate Change (IPCC), and now
    the U.S. National Assessment of Climate Change, both indicate that
    hemispheric or global air temperatures followed a curve developed by
    Dr. Mann and his colleagues in 1999. This curve exhibits two notable
    features. First is a relatively flat and somewhat decreasing trend in
    air temperature that extends from 1000AD to about 1900AD and is
    associated with a relatively high degree of uncertainty. This is
    followed by an abrupt rise in air temperature during the 1900's that
    culminates in 1998 with the highest temperature on the graph. Virtually
    no uncertainty is shown for the data of the last century. The
    conclusion reached by the IPCC and the National Assessment is that the
    1990's are the warmest decade with 1998 being the warmest year of the
    last millennium.
        Despite the large uncertainty, the surprising lack of variability
    in the record gives the impression that climate remained relatively
    unchanged through most of the last millennium--at least until human
    influences began to cause an abrupt increase in temperatures during the
    last century. Interestingly, Mann et al. replace the proxy data for the
    1900's by the instrumental record and no uncertainty characterization
    is provided. This too yields a false impression that the instrumental
    record is consistent with the proxy data and that it is `error free'.
    It is neither. The instrumental record contains numerous uncertainties,
    resulting from a lack of coverage over the world's oceans, an under-
    representation of mountainous and polar regions as well as under-
    developed nations, and the presence of urbanization effects resulting
    from the growth of cities. Even if a modest uncertainty of a
    0.1+ C were imposed on the instrumental record, the claim
    of the 1990's being the warmest decade would immediately become
    questionable, as the uncertainty window would overlap with the
    uncertainty associated with earlier time periods. Note that if the
    satellite temperature record--where little warming has been observed
    over the last 20 years--had been inserted instead of the instrumental
    record, it would be impossible to argue that the 1990's are the warmest
    decade.

                  RATIONALE FOR THE SOON ET AL. INVESTIGATION

        So we were left to question why the Mann et al. curve seems to be
    at variance with the previous historical characterization of climatic
    variability. Investigating more than several hundred studies that have
    developed proxy records, we came to the conclusion that nearly all of
    these records show considerable fluctuations in air temperature over
    the last millennium. Please note that we did not reanalyze the proxy
    data--the original analysis from the various researchers was left
    intact. Most records show the coldest period is commensurate with at
    least a portion of what is termed the ``Little Ice Age'' and the
    warmest conditions are concomitant with at least a portion of what is
    termed the ``Medieval Warm Period''.
        But our conclusion is entirely consistent with conclusions reached
    by Drs. Bradley and Jones that not all locations on the globe
    experienced cold or warm conditions simultaneously. Moreover, we chose
    not to append the instrumental record, but to compare apples-with-
    apples and determine if the proxy records themselves indeed confirm the
    claim of the 1990's being the warmest decade of the last millennium.
    That claim is not borne out by the individual proxy records.
        However, the IPCC report, in the chapter with Dr. Mann as a lead
    author and his colleagues as contributing authors, also concludes that
    research by Drs. Mann, Jones, and their colleagues ``support the idea
    that the 15th to 19th centuries were the coldest of the millennium over
    the Northern Hemisphere overall.'' Moreover, the IPCC report also
    concludes that the Mann and Jones research ``show[s] temperatures from
    the 11th to 14th centuries to be about 0.2+ C warmer than those from
    the 15th to 19th centuries.'' This again is entirely consistent with
    our findings. Where we differ with Dr. Mann and his colleagues is in
    their construction of the hemispheric averaged time-series, their
    assertion that the 1990's are the warmest decade of the last
    millennium, and that human influences appear to be the only significant
    factor on globally averaged air temperature. Reasons why the Mann et
    al. curve fails to retain the fidelity of the individual proxy records
    are detailed statistical issues into which I will not delve. But our
    real difference of opinion focuses solely on the Mann et al. curve and
    how we have concluded it misrepresents the individual proxy records. In
    a very real sense, this is an important issue that scientists must
    address before the Mann et al. curve is taken as fact.
        Our work has been met with much consternation from a variety of
    sources and we welcome healthy scientific debate. After all, it is
    disagreements among scientists that often lead to new theories and
    discoveries. However, I am aware that the editors of the two journals
    that published the Soon et al. articles have been vilified and the
    discussion has even gone so far as to suggest that Drs. Soon and
    Baliunas be barred from publishing in the journal Climate Research.
    Such tactics have no place in scientific debate and they inhibit the
    free exchange of ideas that is the hallmark of scientific inquiry.

                CLIMATE IS MORE THAN MEAN GLOBAL AIR TEMPERATURE

        In closing, let me state that climate is more than simply annually-
    averaged global air temperature. Too much focus has been placed on
    divining air temperature time-series and such emphasis obscures the
    true issue in understanding climate change and variability. If we are
    truly to understand climate and its impacts and driving forces, we must
    push beyond the tendency to distill it to a single annual number. Proxy
    records, which provide our only possible link to the past, are
    incomplete at best. But when these records are carefully and
    individually examined, one reaches the conclusion that climate
    variability has been a natural occurrence, and especially so over the
    last millennium. And given the uncertainties in the proxy and
    instrumental records, an assertion of any decade as being the warmest
    in the last millennium is premature.
        I'm sorry that a discussion that is best conducted among scientists
    has made its way to a U.S. Senate committee. But hopefully a healthy
    scientific debate will not be compromised and we can push on toward a
    better understanding of climate change.
        I again thank you for the privilege of speaking before you today.

                                   __________

      Prepared Statement of Leonard Levin, Ph.D., Technical Leader, EPRI,
                             Palo Alto, California

        I am Leonard Levin, technical leader at EPRI, which is a non-
    profit, collaborative organization conducting energy-related R&D in the
    public interest. Our members are public and private organizations in
    the electricity and energy fields, and we now serve more than 1000
    energy and governmental organizations in more than 40 countries. These
    remarks constitute a synthesis of current research on environmental
    mercury, and are not a representation of official EPRI position.

                                  INTRODUCTION

        As a global pollutant, the impact of mercury on the human
    environment is a critical issue that EPRI and the scientific community
    have been examining for many years. As the scientific understanding of
    where mercury originates nationally and globally, combined with the new
    health data, continues to be refined, it can help inform decisions
    regarding its management. I would like to address three key questions
    where new findings have emerged. First, where does mercury found in the
    U.S. environment originate? Second, how much has mercury in fish
    changed in the last few decades? And third, how do potential mercury
    management steps change the amount of mercury depositing to the earth's
    surface in the U.S.?

             WHERE DOES MERCURY IN THE U.S. ENVIRONMENT ORIGINATE?

        Mercury is clearly a global issue. Recent estimates are that, in
    1998, some 2340 tons of mercury were emitted globally through
    industrial activity; of these, more than half, or 1230 tons, came from
    Asian countries, primarily China\1\. These findings are similar to
    those of other global inventories\2\. In addition, it is estimated that
    another 1300 tons of mercury emanates from land-based natural sources
    globally, including abandoned mining sites and exposed geological
    formations. Another 1100 tons or so issues from the world's oceans,
    representing both new mercury emitted by undersea vents and volcanoes,
    and mercury cycled through the ocean from the atmosphere previously.
    Recent findings from the large United States-Canadian METAALICUS field
    study in Ontario, Canada showed that a fairly small amount of deposited
    mercury, no more than 20 percent or so, re-emits to the atmosphere,
    even over a 2-year period. The implications of this are profound:
    mercury may be less mobile in the environment than we previously
    thought; once it is removed from the atmosphere, it may play less of a
    role in the so-called ``grasshopper effect\3\ '' where persistent
    global pollutants are believed to successively deposit and re-emit for
    many years and over thousands of miles.
    ---------------------------------------------------------------------------
        \1\ Christian Seigneur, C., K. Vijayaraghavan, K. Lohman, Pr.
    Karamchandani, C. Scott, Global Source Attribution for Mercury
    Deposition in the United States, submitted to Environ. Sci. Technol.,
    2003.
        \2\ Jozef M. Pacyna, Elisabeth G. Pacyna, Frits Steenhuisen and
    Simon Wilson, Mapping 1995 global anthropogenic emissions of mercury,
    Atmospheric Environment 37 (S1) (2003) pp. 109-117.
        \3\ Environment Canada, The Grasshopper Effect and Tracking
    Hazardous Air Pollutants, The Science and the Environment Bulletin,
    May/June 1998.
    ---------------------------------------------------------------------------
        Recent studies by EPRI have shown that the mercury depositing into
    the U.S. from the atmosphere may originate at very distant points.
    Model assessments show that, for \3/4\ of the area of the continental
    United States, more than 60 percent of the mercury received originates
    outside U.S. borders, from other countries or even other continents.
    Only 8 percent of U.S. territory receives \2/3\ or more of its mercury
    from U.S. domestic sources, and less than 1 percent of U.S. territory
    gets 80 percent or more of its mercury from sources within the U.S. One
    implication of this dichotomy between mercury sources and the U.S.
    areas impacted is that there may be a ``management floor'' for U.S.
    mercury, a level below which the amount of mercury depositing to the
    surface cannot be reduced.
        Additional evidence for the external origins of much of the mercury
    in the U.S. environment was gathered over the last 2 years by aircraft
    experiments carried out by EPRI, the National Center for Atmospheric
    Research, and a number of U.S., Asian, and Australian investigators.
    One set of flights measured significant mercury in winds entering the
    Pacific Ocean from Shanghai; China; researchers tracked the Chinese
    mercury plume over the Pacific for 400 miles toward America. A second
    set of flights from Monterey, California, found that same plume from
    China crossing the California coast, and a second, higher plume of
    enriched mercury originating in Central Asia also moving into the U.S.
    The global nature of mercury in the U.S. has been clearly demonstrated.

      WHAT ARE THE PRIMARY SOURCES OF MERCURY IN FISH AND THE ENVIRONMENT?

        For much of the twentieth century, mercury was an essential part of
    industrial products, such as batteries and switches, or a key
    ingredient in such other products as house paints. These industrial
    uses of the element declined significantly in the latter half of the
    century, and are now less than 10 percent of their use of fifty years
    ago.\4\ Professor Francois Morel of Princeton University and colleagues
    recently analyzed newly caught Pacific tuna for mercury\5\, and
    compared those results to the mercury content of similar tuna caught in
    the 1970's. Despite changes in mercury emissions to the atmosphere in
    those thirty years\6\, and a matching increase in the mercury
    depositing; from the atmosphere to rivers and oceans below, Prof Morel
    found that mercury levels in tuna have not changed over that time. One
    conclusion is that the mercury taken up by such marine fish as tuna is
    not coming from sources on land, such as utility power plants, but from
    natural submarine sources of mercury, including deep sea volcanoes and
    ocean floor vents. The implications are that changes in mercury sources
    on the continents will not affect the mercury levels found in open
    ocean foodfish like tuna.
    ---------------------------------------------------------------------------
        \4\ Engstrom, D.R., E.B. Swain, Recent Declines in Atmospheric
    Mercury Deposition in the Upper Midwest, Environ. Sci. Technol. 1997,
    31, 960-967.
        \5\ Kraepiel, A.M.L., K. Keller, H.B. Chin, E.G. Malcolm, F.M.M.
    Morel, Sources and Variations of Mercury in Tuna, Meeting of American
    Society for Limnology and Oceanography, Salt Lake City, Utah: January
    2003.
        \6\ Slemr, F., E-G. Brunke, R. Ebinghaus, C. Temme, J. Munthe, I.
    Wangberg, W. Schroeder, A. Stgeffen, T. Berg, Worldwide trend of
    atmospheric mercury since 1977, Geophys. Res. Ltrs., 30 (10), 23-1 to
    23-4
    ---------------------------------------------------------------------------
        An estimate in 2001 by scientists of the Geological Survey of
    Canada and others\7\ estimated that geological emissions of mercury, as
    well as emissions from inactive industrial sites on land, are five to
    seven times as large as had been estimated earlier. Recent measurements
    in the stratosphere by EPRI researchers show a rapid removal of mercury
    in the upper atmosphere, allowing for additional sources at the surface
    while still maintaining the measured rates of deposition and removal
    needed for a global balance of sources and sinks. As a result, it is
    now possible to attribute a greater fraction of the mercury entering
    U.S. waters to background natural sources rather than industrial
    emissions from the U.S. or elsewhere globally.
    ---------------------------------------------------------------------------
        \7\ Richardson G. M., R. Garrett, I. Mitchell, M. Mah-Paulson, T.
    Hackbarth, Critical Review On Natural Global And Regional Emissions Of
    Six Trace Metals To The Atmosphere, International Lead Zinc Research
    Organization, International Copper Association, Nickel Producers
    Environmental Research Association.
    ---------------------------------------------------------------------------
       HOW COULD POTENTIAL MERCURY REDUCTIONS CHANGE MERCURY DEPOSITION?

        EPRI recently completed work to assess the consequences, of further
    mercury emissions reductions for mercury in the atmosphere, U.S.
    waterways, and fish\8\. The approach used linked models of atmospheric
    mercury chemistry and physics with analyses of Federal data on mercury
    in fish in the U.S. diet, along with a model of costs needed to attain
    a given reduction level.
    ---------------------------------------------------------------------------
        \8\ EPRI Technical Report 1005224, ``A Framework for Assessing the
    Cost-Effectiveness of Electric Power Sector Mercury Control Policies,''
    EPRI, Palo Alto, CA, May 2003.
    ---------------------------------------------------------------------------
        Current U.S. utility emissions of mercury are about 46 tons per
    year. At the same time, a total of about 179 tons of mercury deposit
    each year in the U.S., from all sources global and domestic. One
    proposed management scenario examined cutting these utility emissions
    by 47 percent, to 24 tons per year. The analysis showed that this cut
    results in an average 3 percent drop in mercury deposition into the
    U.S. Some isolated areas totaling about 1 percent of U.S. land area
    experience drops of up to 30 percent in mercury deposited. The cost
    model used in association with these calculations showed utility costs
    to reach these emission control levels would amount to between $2
    billion and $5 billion per year over 12 years. This demonstrated that
    U.S. mercury patterns are relatively insensitive to the effects of this
    single category of sources.
        In addition, most of the fish consumed in the U.S. comes from ocean
    sources, which would be only marginally affected by a global reduction
    of 24 tons of mercury per year due solely to U.S. controls. Wild fresh
    water fish in the U.S. would be expected to show a greater reduction in
    mercury content, but are a relatively small part of the U.S. diet
    compared to ocean or farmed fish. When these changes were translated
    into how much less mercury enters the U.S. diet, we found that 0.064
    percent fewer children would be born ``at risk'' due to their mothers
    taking in less mercury from consumed fish. These results were based on
    the Federal dietary fish consumption data. So, a drop of nearly half in
    utility mercury emissions results in a drop of 3 percent (on average)
    in mercury depositing to the ground, and a drop of less than one-tenth
    of a percent in the number of children ``at risk.''

                        DECISIONMAKING UNDER UNCERTAINTY

        These recent findings on mercury sources, dynamics, and management
    are a small part of the massive international research effort to
    understand mercury and its impacts on the human environment. EPRI and
    others, including the U.S. Environmental Protection Agency and the U.S.
    Department of Energy, are racing to clarify the complex interactions of
    mercury with geochemical and biological systems, vital to understanding
    mercury's route to human exposure and potential health effects. With
    this improved understanding, informed decisions can be made on the best
    ways to manage mercury.
        Thank you for the opportunity to deliver these remarks to the
    Committee.

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           Statement of Deborah C. Rice, Ph.D., Maine Department of
                    Environmental Protection, Augusta, Maine

         I would like to thank the Committee for this opportunity to
    present information on the adverse health consequences of exposure to
    methylmercury in the United States. Until 3 months ago, I was a senior
    toxicologist in the National Center for Environmental Assessment in the
    Office of Research and Development at the Environmental Protection
    Agency. I am a co-author of the document that reviewed the scientific
    evidence on the health effects of methylmercury for EPA, and which
    included the derivation of the acceptable daily intake level for
    methylmercury.
         I would like to focus my presentation on four points that are key
    to understanding the health-related consequences of environmental
    mercury exposure. One: there is unequivocal evidence that methylmercury
    harms the developing human brain. Two: the Environmental Protection
    Agency used analyses of three large studies in its derivation of an
    acceptable daily intake level, including the study in the Seychelles
    Islands which found no adverse effects. Three: 8 percent of women of
    child-bearing age in the United States have levels of methylmercury in
    their bodies above this acceptable level. And four: cardiovascular
    disease in men related to low levels of methylmercury has been
    documented, suggesting that a potentially large segment of the
    population may be at risk for adverse health effects.
         The adverse health consequences to the nervous system of
    methylmercury exposure in humans were recognized in the 1950's with the
    tragic episode of poisoning in Minamata Bay in Japan, in which it also
    became clear that the fetus was more sensitive to the neurotoxic
    effects of methylmercury than was the adult. A similar pattern of
    damage was apparent in subsequent episodes of poisoning in Japan and
    Iraq. These observations focused the research community on the question
    of whether exposure to concentrations of methylmercury present in the
    environment might be producing neurotoxic effects that were not
    clinically apparent.
         As a result, over half a dozen studies have been performed around
    the world to explore the effects of environmental methylmercury intake
    on the development of the child. Studies in the Philippines (Ramirez et
    al., 2003), the Canadian Arctic (McKeown-Eyssen et al., 1983), Ecuador
    (Counter et al., 1998), Brazil (Grandjean et al., 1999), French Guiana
    (Cordier et al., 1999) and Madeira (Murata et al., 1999) all found
    adverse effects related to the methylmercury levels in the children's
    bodies. These included auditory and visual effects, memory deficits,
    deficits in visuospatial ability, and changes in motor function.
         In addition to the above studies, there have been three major
    longitudinal studies on the effects of exposure to the mother on the
    neuropsychological function of the child: in the Faroe Islands in the
    North Atlantic (Grandjean et al., 1997), in the Seychelles Islands in
    the Indian Ocean (Myers et al., 1995), and in New Zealand (Kjellstrom
    et al., 1989). Two of these studies identified adverse effects
    associated with methylmercury exposure, whereas the Seychelles Islands
    study did not. Impairment included decreased IQ and deficits in memory,
    language processing, attention, and fine motor coordination. A National
    Research Council (NRC) National Academy of Sciences panel evaluated all
    three studies in their expert review, concluding that all three studies
    were well designed and executed (NRC, 2000). They modeled the
    relationship between the amount of methylmercury in the mother's body
    and the performance of the child on a number of neuropsychological
    tests. From this analysis, they calculated a defined adverse effect
    level from several types of behavior in each of the three studies.
    These adverse effect levels represent a doubling of the number of
    children that would perform in the abnormally low range of function.
    The National Academy of Sciences panel also calculated an overall
    adverse effect level of methylmercury in the mother's body for all
    three of the studies combined, including the negative Seychelles study.
    Thus the results of all three studies were included in a quantitative
    manner by the NRC.
         The Environmental Protection Agency (EPA) used the analyses of the
    NRC in the derivation of the reference dose, or RfD, for methylmercury.
    The RfD is a daily intake level designed to be without deleterious
    effects over a lifetime. The EPA divided the defined deleterious effect
    levels calculated by the NRC by a factor of 10 in its RfD derivation.
    There are two points that need to be made in this regard. First, the
    factor of 10 does not represent a safety factor of 10, since the
    starting point was a level that doubled the number of low-performing
    children. Second, the EPA performed the relevant calculations for a
    number of measurements for each of the two studies that found
    deleterious effects as well as the integrative analysis that included
    all three studies modeled by the NRC, including the negative Seychelles
    study. The RfD is 0.10  g/kg/day based on the Faroe Islands study alone
    or the integrative analysis of all three studies. The RfD would be
    lower than 0.10  g/kg/day if only the New Zealand study had been
    considered. Only if the negative Seychelles Islands study were used
    exclusively for the derivation of the RfD, while ignoring the values
    calculated for the Faroe Islands and New Zealand studies, would the RfD
    be higher than the current value of 0.10  g/kg/day. EPA believes that
    to do so would be scientifically unsound, and would provide
    insufficient protection to the U.S. population.
         A substantial portion of U.S. women of reproductive age have
    methylmercury in their bodies that is above the level that corresponds
    to the EPA's RfD. Data collected over the last 2 years as part of the
    National Health and Nutritional Examination Survey (NHANES 99+)
    designed to represent the U.S. population (CDC, Web) revealed that
    about 8 percent of women of child-bearing age had blood levels of
    methylmercury above the level that the U.S. EPA believes is ``safe''
    (Schober et al., 2003). This translates into over 300,000 newborns per
    year potentially at risk for adverse effects on intelligence and
    memory, ability to pay attention, ability to use language, and other
    skills that are important for success in our highly technological
    society.
         I would like to further comment here on the use of a factor of 10
    by EPA to derive the allowable daily intake level (RfD) for
    methylmercury from the defined effect levels calculated by the National
    Research Council. The RfD corresponds to roughly 1 part per million
    (ppm) of methylmercury in maternal hair, from the defined effect level
    of about 11 ppm calculated by the NRC. But we know that there is no
    evidence of a threshold below which there are no adverse effects down
    to about 2-3 ppm in hair, the lowest levels in the Faroe Islands study.
    In fact, there is evidence from both the Faroe Islands (Budtz-Jorgensen
    et al., 2000) and New Zealand (Louise Ryan, Harvard University,
    personal communication) studies that the change in adverse effect in
    the child as a function of maternal methylmercury level may be greater
    at lower maternal methylmercury levels than at higher ones. Therefore,
    the so-called safety factor almost certainly is less than 10, and may
    be closer to non-existent. Babies born to women above the RfD may be at
    actual risk, and not exposed to a level 10 times below a risk level.
         There is an additional concern regarding the potential for adverse
    health consequences as a result of environmental exposure to
    methylmercury. Several years ago, a study in Finnish men who ate fish
    found an association between increased methylmercury levels in hair and
    atherosclerosis, heart attacks, and death (Salonen et al., 1995, 2000).
    Two new studies in the U.S. and Europe found similar associations
    between increased methylmercury levels in the bodies of men and
    cardiovascular disease (Guallar et al., 2002; Yoshizawa et al., 2002).
    Effects have been identified at hair mercury levels below 3 ppm. It is
    not known whether there is a level of methylmercury exposure that will
    not cause adverse effects. It is important to understand that the
    cardiovascular effects associated with methylmercury may put an
    additional, very large proportion of the population at risk for adverse
    health consequences as a result of exposure to methylmercury from
    environmental sources.
         In summary, there are four points that I would like the Committee
    to keep in mind. First, at least eight studies have found an
    association between methylmercury levels and impaired
    neuropsychological performance in the child. The Seychelles Islands
    study is anomalous in not finding associations between methylmercury
    exposure and adverse effects. Second, both the National Research
    Council and the Environmental Protection Agency included the Seychelles
    Islands study in their analyses. The only way the acceptable level of
    methylmercury could be higher would be to ignore the two major positive
    studies that were modeled by the NRC, as well as six smaller studies,
    and rely solely on the single study showing no negative effects of
    methylmercury. Third, there is a substantial percentage of women of
    reproductive age in the United States with levels of methylmercury in
    their bodies above what EPA considers a safe level. As a result of
    this, over 300,000 newborns each year are exposed to methylmercury
    above levels U.S. EPA believes to be ``safe''. Fourth, increased
    exposure to methylmercury may result in atherosclerosis, heart attack,
    and even death from heart attack in men, suggesting that an additional
    large segment of the population may be at risk as a result of
    environmental methylmercury exposure.
         Thank you for your time and attention.

                                     ______

    Responses by Deborah Rice to Additional Questions from Senator Jeffords

        Question 1. In testimony, you indicated that ``there might be
    virtually no safety factor at all'' with respect to the effect level
    for mercury exposure. Does that mean that the reference dose should be
    lowered further? If so, what would be a safer and more protective
    reference dose?
        Response. The current reference dose (RfD) is based on a cord blood
    mercury concentration associated with a defined risk: a doubling of the
    number of children performing in the abnormally low range. A total
    uncertainty factor of 10 was applied to account for inter-individual
    variability. There are several decisions made by EPA that, if
    different, would have resulted in a lower RfD.
        (a) It was assumed that the ratio of cord-to-maternal blood mercury
    was one. Subsequent analyses of 10 studies revealed that cord blood has
    more mercury compared to maternal blood. The average ratio is 1.7:1.0,
    with the upper 5 percent of women having a ratio of 3.3:1.0. Based on
    just the average ratio, if no other decisions were changed, the RfD
    would be reduced from 1.0  g/kg/day to 0.6  g/kg/day.
        (b) As was recommended by the NAS expert committee, EPA assumed
    that there was a linear relationship between adverse effects on a
    number of neuropsychological endpoints and the level of mercury in cord
    blood or maternal hair. In fact, the data from the Faroe Island study
    best fit a supra-linear model: i.e., the slope was actually greater at
    lower body burdens (see figure below). It turns out that this was also
    true for the New Zealand study. Recently, a study was published
    reporting a supra-linear shape to the relationship between adverse
    behavioral performance and blood lead levels in children. So this
    phenomenon, while somewhat counter-intuitive, may be real. Using the
    ``best fit'' model rather than forcing a linear relationship would
    result in a lower estimate of the defined adverse starting point (a
    doubling of the number of children performing in the abnormally low
    range), and thereby a lower RfD.

        [GRAPHIC] [TIFF OMITTED] T2381.168

        (c) EPA used a total uncertainty factor (UF) of 10 to derive the
    RfD, which is designed to provide a margin of safety against adverse
    effects. EPA typically applies an UF of 10 for inter-individual
    variability if the starting point is a no-observable-adverse-effect-
    level (NOAEL). If the starting point is the lowest level that has been
    demonstrated to produce an effect, with a NOAEL not identified, the EPA
    applies an additional UF, usually 10. In the case of methylmercury,
    even though the starting point was a level associated with an effect,
    only a total factor of 10 was applied, rather than the more typical
    100. In addition, the UF of 10 for inter-individual variability is
    presumed to account for differences in both metabolism and response of
    the target organ (sensitivity) between individuals. The variability in
    metabolism of methylmercury between women has been demonstrated to be
    about 3. The variation in cord-maternal blood levels between women may
    be also about 3. These would be multiplied together to equal about 10.
    That allows no room for any variation in response of the fetal brain to
    methylmercury, which is undoubtedly not the case. Therefore a total UF
    of 10 is almost certainly inadequate to protect the most sensitive
    portion of the population.
        The issue of whether the reference dose should be lowered, and if
    so, the appropriate value, requires thorough evaluation by a group of
    expert risk assessors and other scientists. Any new evaluation of the
    RfD should also include evaluation of the levels of methylmercury that
    produce adverse cardiovascular effects documented in several studies of
    adult males. It is currently unknown whether these effects occur at
    lower or higher levels than those that produce developmental
    neurotoxicity.

        Question 2. What is a reasonable estimate of the approximate
    average mercury concentrations in non-commercial fish in the U.S.?
        Response. EPA keeps an extensive data base of fish tissue
    contaminant levels from inland water bodies compiled by individual
    states (http://www.epa.gov/ost/fish/mercurydata.html). Data for average
    levels of mercury for 1987-2000 are in the attached figure. Average
    tissue levels vary significantly depending on species, such that
    deriving an ``average'' for all species is not particularly
    informative. Averages for different species range from 0.1 ppm for
    herring and whitefish to 0.9 ppm for bowfin. As can be seen from the
    figure, the average level for many species is below the 0.3 ppm level
    recommended by EPA (Water Quality Criterion for the Protection of Human
    Health: Methylmercury, OST, Office of Water, 2001, EPA-823-R-01-001).
    Approximately one third of species have average concentrations above
    this. Even for species with averages below 0.3 ppm, some samples will
    exceed this level. For species with averages about 0.5 ppm, more than
    half the samples will exceed the EPA recommended limit, whereas half
    the samples will exceed the 0.5 ppm action limit set by many European
    countries and Canada. Ocean fish and sharks can have levels that are
    considerably higher. For example, blue marlin average 3.08 ppm, with
    the highest level for an individual at 6.8 ppm (Florida Marine Research
    Institute Technical Reports' Mercury Levels in Marine and Estuarine
    Fishes of Florida. 1989-2001: FMRI Technical Report TR-9, Second
    Edition, Revised, 2003). Sharks such as white shark averaged over 5
    ppm, with the highest value for a shark at 10 ppm (ibid.) These are
    non-commercial sport-caught species.

        Question 3. You indicated that the NHANES data does not adequately
    capture the individuals or subpopulations that are likely to be the
    most exposed to non-commercial fish mercury concentrations above the
    reference dose. Are you aware of any work underway to collect this kind
    of data and hopefully protect these people from overexposure?
        Response. There have been a number of relatively small studies
    focusing on fish intake by groups that consume large amounts of fish,
    specifically sports fishers and subsistence fishing communities. Most
    of these efforts have been by individual states or tribes. EPA is
    developing a data base of these studies, most of which are unpublished
    and not in the public domain, a project which I managed before leaving
    the agency. The data base currently includes about 70 studies (contact
    project officer Cheryl Itkin, EPA/ORD/National Center for Environmental
    Assessment, Washington, D.C. at itkin.cheryl@epa.gov).
        There are also several published studies: Bellanger, T.M., Caesar,
    E.M., Trachtman, L. 2000. Blood mercury levels and fish consumption. J.
    La. Med. Soc, 152:64-73; Burge, P., Evans, S. 1994. Mercury
    contamination in Arkansas gamefish. A public health perspective. J.
    Ark. Med. Soc. 90:542-544; Hightower, J.M., Moore, D. 2003. Mercury
    levels in high-end consumers offish. Environ. Health Perspect. 111:604-
    608; and Knobeloch, L.M., Ziamik, M., Anderson, H.A., Dodson, V.N.
    1995. Imported seabass as a source of mercury exposure: A Wisconsin
    case study. Environ. Health Perspect. 103:604-606.
        Protecting individuals who may be at greater risk from over-
    exposure to methylmercury presents significant challenges. Forty states
    have fish advisories for inland waters, based largely on levels of
    mercury in fish. Some states have levels that are specific to
    particular water bodies, others have statewide advisories for all water
    bodies. Advisories typically are set with regard to species of fish,
    designating them as e.g. ``no restriction'', ``eat no more than once a
    week'', or ``eat no more than once a month''. If a person eats a fish
    from one restricted category they are meant not to eat fish from
    another restricted category in that month. Signs are posted by some
    states at specific water bodies, and most if not all states distribute
    literature related to fish advisories with fishing licenses. Some
    tribes have also performed significant outreach related to issues of
    contaminants in wild foods. Immigrant communities are often the most
    difficult to inform, as a result of language and cultural barriers.
    Minnesota, for example, has made a substantial effort to work with
    immigrant communities, publishing appropriate information in relevant
    languages, as well as performing extensive outreach activities. A few
    other states have made efforts in this regard as well. Some communities
    rely on fish as a significant protein source for both cultural and
    economic reasons. It is unfortunate indeed that these communities are
    risking adverse health outcomes by consuming what should be a very
    healthful food.

        Question 4. Please describe the purposes and intended uses of the
    various Federal agencies' exposure limits for methyl mercury.
        Response. EPA, FDA, and ATSDR have set exposure limits for
    methylmercury. The reference dose (RfD) set by EPA is designed to
    represent an ``estimate of a daily exposure to the human population
    (including sensitive subgroups) that is likely to be without
    appreciable risk of deleterious [non-cancer] effects during a
    lifetime'' (http://www.epa.gov/iris/index.html).
        The minimal risk level (MRL) of ATSDR is ``an estimate of the daily
    human exposure to a hazardous substance that is likely to be without
    appreciable risk of adverse noncancer health effects over a specified
    duration of exposure''. MRLs may be derived for acute (1-14 days),
    intermediate (15-364 days) or chronic durations (over 364 days). ATSDR
    states that ``[t]hese substance-specific estimates, which are intended
    to serve as screening levels, are used by ATSDR health assessors and
    other responders to identify health effects that may be of concern at
    hazardous waste sites. It is important to note that MRLs are not
    intended to define clean-up or action levels for ATSDR or other
    Agencies.'' [bold original] (http://www.atsdr.cdc.gov/mrls.html) It is
    critical to understand that ATSDR is involved in clean-up activities.
    The MRLs are designed to identify chemicals that are important for
    clean-up decisions. They are not intended as health-protective levels
    for the general population, or for a lifetime.
        The FDA acceptable daily intakes (ADI) is ``the amount of a
    substance that can be consumed daily over a long period of time without
    appreciable risk'' (http://www.fda.gov; http://www.cfsan.fda.gov/-
    acrobat/hgstud16.pdf). For contaminants in food, FDA uses the ADI to
    derive an Action Level, ``which defines the maximum allowable
    concentration of the contaminant in commercial food.'' In other words,
    the Action Level is supposed to be health-based.
        The RfD and the ADI are designed to protect the general population
    from adverse effects from contaminants in food over a lifetime of
    exposure, including protection of sensitive populations. In contrast,
    the MRL is designed for a different purpose: identifying contaminants
    that may be important in making decisions regarding clean-up of
    contaminated sites.
        The exposure limits from U.S. agencies are as follows:

            EPA RfD: 0.1  g/kg/day
            ATSDR MRL: 0.3  g/kg/day
            FDA ADI: 0.4  g/kg/day

        Question 5. What is the preferred measurement methodology for most
    reliably determining and predicting the effect on children's
    developmental health of methyl mercury exposure?
        Response. There has been considerable discussion within the
    academic and regulatory communities regarding what might be a ``best''
    test or test battery for determining adverse neuropsychological
    function in children exposed to methylmercury. There are two basic
    strategies that have been used to assess methylmercury neurotoxicity.
    The first is the use of standard clinical instruments such as measures
    of IQ. These have the advantage of being standardized for the
    population, as well as assessing a wide range of functional domains.
    However, because they may be measuring a number of functions that are
    not affected in addition to those that are, the results can be
    ``diluted'', and therefore these tests may be less sensitive than a
    more focused approach. The second approach is to choose domain-specific
    tests based on the known effects of higher levels of the toxic
    chemical, if such effects are known. This strategy has the advantage of
    being potentially more sensitive than using broad-based clinical
    instruments. On the other hand, using domainspecific tasks runs the
    risk of looking at the wrong functions.
        The investigators of the Faroe Islands study used a number of
    domain-specific tasks, based on the effects of high-level methylmercury
    exposure as well as the pathological changes in specific brain areas
    produced by methylmercury. The Faroe Island study found deficits in
    these' tasks. The investigators of the Seychelles study used standard
    clinical instruments that assessed a little bit of a lot of functions,
    which were standardized for a U.S. population rather than the
    Seychellois population. They found no effect of methylmercury. In
    contrast, the investigators of the New Zealand study, also using
    standard clinical instruments, did identify mercury-related deficits.
        The consensus of the research community seems to be that a
    combination of both approaches should be used, The standard clinical
    instruments (e.g. full-scale IQ) are comprised of subscales (e.g.
    verbal, visuospatial) that can be used to explore more specific
    functional domains. Researchers should also use what is known about the
    behavioral and neuropathological effects of methylmercury to design
    domainspecific tests, with the hope that these will be maximally
    sensitive. To date, deficits in memory, language processing,
    visuospatial ability, motor function, and attention have been
    identified to be adversely affected by in utero methylmercury exposure.
    Hearing may also be adversely affected. New studies, or continued
    testing of current cohorts, should build on this knowledge to hone in
    even further on specific behavioral functions.

        Question 6. In 1974, the FDA established a mercury action limit of
    .5 parts per million in fish. This was changed in 1979 to 1 part per
    million. What was the basis for this change?
        Response. FDA set an action level of 0.5 ppm for mercury in fish in
    1969,' in response to the recognition. of the devastating consequences
    of fetal exposure to methylmercury in the poisoning episodes in
    Minamata and Niigata, Japan. This level was reaffirmed in 1974, citing
    concerns about damage to the fetus at lower exposures than are harmful
    to the adult. The level was changed in 1979 as a result of a lawsuit by
    the fishing industry that resulted in a court ruling based on
    socioeconomic impacts presented by the National Marine Fisheries
    Service (NMFS). They argued that raising the action level would expand
    the number of fisheries available for exploitation and expand the
    profits of the fishing industry (Fed. Reg. 3990, 3992, 1979). The
    notice was a withdrawal of the proposed rulemaking and terminated a
    rulemaking procedure to codify the (then) existing action level
    limiting the amount of unavoidable mercury residues permitted in fish
    and shellfish of 0.5 ppm. The FR notice also indicates that ``[t]he
    Food and Drug Administration will continue to monitor mercury levels in
    fish so that if there is any change in mercury residue levels as a
    result of raising the action level, or if there is any other change in
    the information regarding mercury in fish, the action level can be
    revised accordingly.'' Thus, the action limit is not health-based, but
    was established for economic considerations.

        Question 7. What, if anything, should consumers of fish in the
    Great Lakes region and other areas that are downwind of major mercury
    emission sources such as coal-fired power plants, chlor-alkali
    manufacturing facilities and; waste incinerators, be advised to do with
    respect to limiting their methyl mercury exposure?
        Response. Unfortunately, the majority of inland lakes and rivers
    are contaminated with mercury. Methylmercury is created from mercury by
    microorganisms in the water. Methylmercury is bioconcentrated as it is
    passed up the food chain, with older and larger fish at the top of the
    food chain containing more methylmercury than smaller fish or fish that
    are lower on the food chain. Methylmercury exposure in humans is
    exclusively from eating contaminated fish. Forty states have explicit
    fish advisories as a result of mercury contamination for consumption of
    fish based on species, size, and in some states specific water bodies.
    There were 2,242 advisories in 2000, up 8 percent o from 1999 and up
    149 percent from 1993. By far the greatest number of fish advisories
    for mercury are around the Great Lakes and in the Northeastern states.
    Consumers are advised to carefully follow State fishing advisories for
    inland fish. There is an increasing recognition that commercial and/or
    ocean fish may represent a significant source of methylmercury
    exposure. Currently, FDA advises pregnant women, nursing mothers and
    young children against eating any shark, swordfish, tilefish, or king
    mackerel. Recent data indicate that canned white (albacore) tuna may
    have substantial levels of methylmercury, and so should be consumed
    seldom, especially by children. Other species such as fresh tuna and
    halibut may also have significant levels of methylmercury. Intake of
    purchased fish that are potentially high in methylmercury should be
    included by individuals in determining safe fish intake over a specific
    time period. In other words, consumers need to have detailed
    information on fish species from both commercial and non-commercial
    sources to keep track of their potential methylmercury intake.
        This is an unsatisfactory solution, since fish should be a very
    healthful food. Moreover, sport fishing is an important economic
    resource in many areas, and some individuals rely on fishing for a
    substantial portion of their protein, particularly in certain immigrant
    communities. The ultimate solution is of course to decrease
    environmental deposition of mercury.

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              Statement of Dr. Gary Myers, Pediatric Neurologist
                     and Professor, University of Rochester

        Thank you for the opportunity to present the views of our research
    group on the health effects of methylmercury (MeHg) exposure. My name
    is Gary Myers. I am a pediatric neurologist and professor at the
    University of Rochester in Rochester, New York and one member of a
    large team that has been studying the human health effects of MeHg for
    nearly 30 years. For nearly 20 years our group has specifically studied
    the effects of prenatal MeHg exposure from fish consumption on child
    development.

                               MERCURY POISONINGS

        In the 1950's, massive industrial pollution for over two decades in
    Japan resulted in high levels of MeHg in ocean fish. Several thousand
    cases of human poisoning from consuming the contaminated fish were
    reported. The precise level of human exposure causing these health
    problems was never determined, but was thought to be high. During that
    epidemic pregnant women who themselves had minimal or no clinical
    symptoms of MeHg poisoning delivered babies with severe brain damage
    manifested by cerebral palsy, seizures and severe mental retardation.
    This suggested that MeHg crosses the placenta from the mother to the
    fetus and that the developing nervous system is especially sensitive to
    its toxic effects.
        In 1971-1972 there was an epidemic of MeHg poisoning in Iraq.
    Unlike the Japanese poisonings, the source of exposure in Iraq was
    maternal consumption of seed grain coated with a MeHg fungicide. Our
    research team studied the children of about 80 women who were pregnant
    during this outbreak. We measured mercury exposure to the fetus using
    maternal hair, the biomarker that best corresponds to MeHg brain level,
    and examined the children. We concluded that there was a possibility
    that exposure as low as 10 ppm in maternal hair might be associated
    with adverse effects on the fetus, although there was considerable
    uncertainty in this estimate. This value is over 10 times the average
    in the United States, but individuals consuming large quantities of
    fish can achieve this level.

                   MERCURY FOUND NATURALLY IN THE ENVIRONMENT

        Mercury is a natural element in the earth's crust. In aquatic
    environments, bacteria can convert inorganic mercury to MeHg. Once MeHg
    enters the food chain, it is bioaccummulated and bioconcentrated. All
    fish contain small amounts, and predatory fish or mammals such as
    whales have larger amounts. Most commercial oceanic fish in the United
    States has < 0.5 ppm MeHg in the muscle, but some freshwater fish have
    > 1 ppm. In comparison, contaminated fish in Japan that caused
    poisoning had up to 40 ppm.
        Everyone who consumes fish is exposed to MeHg, and regular fish
    consumption can lead to hair mercury levels as high as 10 ppm or more.
    The average hair mercury level in the United States is < 1 ppm. If MeHg
    does affect the developing brain at such low levels, mothers who
    consume large amounts of fish would be exposing their babies to this
    risk.
        The hypothesis of our study in the Seychelles was that prenatal
    MeHg from fish consumption might affect child development. Since
    millions of people around the world consume fish as their primary
    source of protein, we decided to investigate the question directly. We
    initiated the Seychelles Child Development Study in 1983 and began
    enrolling subjects in a pilot study in 1987. We selected the Seychelles
    as a sentinel population for the United States for two reasons. First,
    they consume large amounts of fish. The average mother in our main
    cohort ate fish with 12 meals per week or over 10 times that of U.S.
    women. Second, the fish consumed in Seychelles (average mercury content
    0.3 ppm) has approximately the same mercury concentration as commercial
    fish in the United States.

                 THE SEYCHELLES CHILD DEVELOPMENT STUDY (SCDS)

        The SCDS is a collaborative study carried on by researchers at the
    University of Rochester Medical Center in Rochester, NY and the
    Ministries of Health and Education in the Republic of the Seychelles.
    Funding has come from the National Institute of Environmental Health
    Sciences, the Food and Drug Administration, and the governments of
    Seychelles and Sweden. The Republic of the Seychelles is an island
    Nation in the Indian Ocean off the East Coast of Africa.
        Our original hypothesis was that prenatal MeHg exposure at levels
    achieved by regular maternal consumption of fish would be associated
    with adverse effects on child development that could be detected by
    clinical examination, or by the use of developmental tests that have
    previously been used to study the effects of environmental exposures on
    child development.
        The Seychelles was chosen partly because there is no mercury
    pollution and many factors that complicate epidemiological studies of
    low-level exposure are not present. Health care is free, universal and
    readily available. Prenatal care is nearly 100 percent, the birth rate
    is high, and the general health of mothers and children is good.
    Education is free, universal, and starts at age 3.5 years. There is
    limited emigration and both the people and the government were
    cooperative and supportive.
        Before starting a carefully controlled main study, we carried out a
    pilot study. We expected to find only subtle effects on children at
    these levels of exposure. Consequently, it was important to minimize
    any possibility of bias, so a number of decisions were made before the
    study began. First, no one in Seychelles including researchers visiting
    the island would know the exposure level of any child or mother, unless
    our results indicated that children were at risk from prenatal mercury
    exposure. Second, children with a known cause of developmental delay
    (meningitis, very low birth weight, or brain trauma) would not be
    studied. Third, the tests administered would include tests previously
    reported to show associations with MeHg exposure, tests used with other
    toxic exposures, and other tests that might detect subtle changes.
    Fourth, all testing would be performed within specific age windows to
    minimize the effect of age on test interpretation. Fifth, results would
    be adjusted for multiple confounding factors (covariates), including
    things like socioeconomic status, maternal intelligence and birth
    weight, which are known to have independent effects on child
    development and if not accounted for, could bias the results. Sixth,
    the data analysis plan would be determined before the data were
    collected to minimize the possibility that the data would be repeatedly
    analyzed until the anticipated effect was eventually found.
        In 1989-90, we enrolled over 700 mothers and children in the SCDS
    main study. These children were evaluated on five occasions (6, 19, 29,
    66 and 107 months of age) during the past 9 years. When the children
    were about 4 years old their homes were visited and evaluated. The
    study focused on prenatal exposure. This was measured in the mothers'
    hair growing during pregnancy. Postnatal exposure was also periodically
    measured in the children's hair. The exposure of both mothers and
    children ranged from 1 to 27 ppm, the range of concern. The testing was
    extensive with over 57 endpoints being evaluated to date.
        Through 107 months (9 years) and over 57 primary endpoints, the
    study has found only three statistical associations with prenatal MeHg
    exposure. One of these associations was adverse, one was beneficial and
    one was indeterminate. These results might be expected to occur by
    chance and do not support the hypothesis that adverse developmental
    effects result from prenatal MeHg exposure in the range commonly
    achieved by consuming large amounts of fish. The test results do show
    associations with factors known to affect child development such as
    maternal IQ and home environment so there is evidence that the tests
    are functioning well.

                       OUR INTERPRETATION OF THE FINDINGS

        We do not believe that there is presently good scientific evidence
    that moderate fish consumption is harmful to the fetus. However, fish
    is an important source of protein in many countries and large numbers
    of mothers around the world rely on fish for proper nutrition. Good
    maternal nutrition is essential to the baby's health. Additionally,
    there is increasing evidence that the nutrients in fish are important
    for brain development and perhaps for cardiac and brain function in
    older individuals.
        The SCDS is ongoing and we will continue to report our results.
    Presently we are examining a new cohort to determine specific nutrients
    that might influence the effects of MeHg.
        Appendix--Not read before the committee, but included in the
    handout.
        Because of the public health importance of the question being
    studied by the SCDS, the potential exists for differing opinions of
    scientific findings to become highly politicized. The SCDS has received
    only one published criticism (JAMA, 280:737, 1998), but other points
    have been raised at conferences. These questions are addressed here
    individually.
         Why did the SCDS measure mercury in the hair rather than
    in the cord blood? Hair mercury was used because it is the standard
    measure used in nearly all other studies of this question. Mercury is
    thought to enter the hair and brain in a similar fashion. Hair was also
    chosen because hair has been shown to follow blood concentrations
    longitudinally, and samples of hair can recapitulate the entire period
    of exposure, in this case the period of gestation. As part of our
    research we have shown that hair levels reflect levels in the target
    tissue, brain. Measuring mercury in blood requires correction for the
    red blood cell volume (hematocrit) since the mercury is primarily in
    red blood cells and reflects only very recent exposure. It can also
    vary if recent meals with high mercury content are consumed.
         Did the SCDS use subjects whose mercury values were too
    low to detect an association? No, the study's goal was to see if the
    children of women who consume fish regularly were at risk for adverse
    developmental effects from MeHg. Women in Seychelles eat fish daily and
    represent a sentinel population with MeHg levels 10 times higher than
    U.S. women. Because of higher levels of exposure, their children should
    be more likely to show adverse effects if they are present. These
    children show no adverse effects through 9 years of age suggesting that
    eating ocean fish, when there is no local pollution, is safe. However,
    we cannot rule out an adverse effect above 12-15 ppm since we had too
    few cases to substantiate a statistical association if one really
    existed.
         Did the SCDS use the best tests available to detect
    developmental problems? Yes, the SCDS used many of the same
    neurodevelopmental and neuropsychological tests used in other
    developmental studies. These tests are deemed to be excellent measures
    for determining development at the ages studied. The tests examined
    specific domains of children's learning and were increasingly
    sophisticated as the children become older.
         Did the SCDS find expected associations between
    development and birth weight, socioeconomic factors, and other
    covariates? Yes, expected relationships with many covariates such as
    maternal IQ, family socioeconomic status and the home environment were
    found, indicating that our tests were sensitive to developmental
    differences.
         Did the removal of statistical outliers in the analysis
    bias the study? No. It is standard practice among statisticians to
    remove statistical outliers. Outliers are values that are inconsistent
    with the statistical model employed to analyze the data. Every
    statistical analysis depends on a model, and every statistical model
    makes assumptions about the statistical (distributional) properties of
    the data that must be satisfied if the results of the analysis are to
    be interpreted correctly. Sound statistical practice requires that the
    necessary assumptions be checked as part of the statistical analysis.
    Examination of outliers constitutes one of these checks. Statistical
    outliers are defined by the difference between the actual test score
    for a child and the value predicted by the statistical model. Small
    numbers of such outliers occurred in test scores for children with
    widely varying MeHg exposures. The results of all analysis were
    examined both before as well as after the removal of outliers. For
    analyses in the main study the removal of statistical outliers did not
    change the conclusions.
         What about the Faroe Islands study where prenatal MeHg
    exposure was reported to adversely affect developmental outcomes? There
    are substantial differences between the Faroe Islands and Seychelles
    studies. The exposure in the Faroe Islands is from consuming whale meat
    and there is also concomitant exposure to PCBs and other neurotoxins.
    There are also differences in the measurement of exposure and the
    approach to statistical analysis. The Faroe Islands study reported
    associations between cord blood mercury levels and several tests. After
    statistical analysis they attributed the associations to prenatal MeHg
    exposure. Scientific studies are frequently open to different
    interpretations and some scientists do not agree with the researchers'
    interpretation. We believe the Seychelles study of individuals
    consuming fish more closely approximates the U.S. situation.
         Are the children in Seychelles too developmentally robust
    to find the effects of MeHg if they are present? No, the children in
    Seychelles tested similar to U.S. children on nearly all measures apart
    from motor skills where they were more advanced. There is no reason to
    think that they are too robust to show the effects of prenatal MeHg
    exposure if any are present.
         Are children in Seychelles exposed to PCBs or other food-
    born toxins that might have confounded the results? No, sea mammals are
    not consumed in Seychelles and measured PCBs in the children's blood
    were low.
         Should data from the Seychelles be considered interim?
    Maybe. Among developmental studies, a 9-year followup is considered
    very long and should be adequate to identify associations with most
    toxic exposures. However, very subtle effects can be more readily
    tested in older individuals and there is evidence from experimental
    animals that some effects of early mercury exposure may not appear
    until the animal ages.

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                                                       August 18, 2003.
    Hon. James M. Inhofe, Chairman,
    Committee on Environment and Public Works,
    U.S. Senate,
    Washington, DC.
        Dear Mr. Chairman: Thank you for offering me the opportunity to
    respond to certain comments that were made in the EPW committee hearing
    on Tuesday, July 29, of this year. I hope I can clear up any confusion
    that might have been caused by incomplete, misleading or erroneous
    testimony that day.
        The testimony in question by Dr. Michael Mann stated:

              ``It's unfortunate to hear comments about the supposed
            inconsistencies of the satellite record voiced here years after
            that has been pretty much debunked in the peer-reviewed
            literature in Nature and Science. Both journals have, in recent
            years, published . . . articles indicating that in fact, the
            original statement that the satellite record showed cooling was
            flawed because . . . the original author, John Christy, did not
            take into account a drift in the orbit of that satellite, which
            actually leads to a bias in the temperatures . . . Christy and
            colleagues have claimed to have gone back and fixed that
            problem. But just about every scientist who has looked at it
            says that this fix isn't correct and that if you fix it
            correctly then the satellite record actually agrees with the
            surface record, indicating fairly dramatic rates of warming in
            the past two decades.''

        Virtually all of this testimony is misleading or incorrect. I will
    touch on the major problems, point-by-point, and I will try to be
    brief.
        1. Certainly no one has ``debunked'' the accuracy of the global
    climate dataset that we built at The University of Alabama in
    Huntsville (UAH) using readings taken by microwave sensors aboard NOAA
    satellites. This dataset has been thoroughly and rigorously evaluated,
    and has been published in a series of peer-reviewed papers beginning in
    Science (March 1990). The most recent version of the dataset was
    published in May 2003 in the Journal of Atmospheric and Oceanic
    Technology after undergoing a strenuous peer review process.
        2. We, and others, are constantly scrutinizing our techniques to
    find ways to better analyze the data. In every case except one we
    discovered needed improvements ourselves, developed a method for
    correcting the error, and published both the error and the correction
    in peer-reviewed journals. When Wentz, et al. (1998) published their
    research on the effects of orbital decay (the one exception) they
    explained an effect we immediately recognized, but which was partially
    counterbalanced by other factors we ourselves discovered. Since that
    time we have applied the corrections for both orbital decay and other
    factors, and have published the corrected data in peer-reviewed
    journals.
        3. The UAH satellite record does not show cooling in the lower
    troposphere and hasn't shown a long-term cooling trend since the period
    ending in January 1998. I cannot say where this chronic cooling
    misconception originated. Our long-term data show a relatively modest
    warming in the troposphere at the rate of 0.133+ Fahrenheit per decade
    (or 1.33+ Fahrenheit per century) for the period of November 1978 to
    July 2003.
        4. There is no credible version of the satellite dataset that
    ``actually agrees'' with the surface temperature record for the past 25
    years, nor one that shows ``fairly dramatic rates of warming.'' The as-
    yet-unexplained differences between the surface and satellite data are
    at the heart of the controversy over the accuracy of the satellite
    data.
        While much of the surface data remains uncalibrated and
    uncorroborated, we have evaluated our UAH satellite data against
    independent, globally-distributed atmospheric data from the U.S. and
    the U.K. (Hadley Centre) as shown in the figure (enclosure 1). We
    published the results of those comparisons in numerous peer-reviewed
    studies (enclosure 2). In each case we found excellent consistency
    between the satellite data and the atmospheric data. One should note
    that such independent corroboration has not been performed on the other
    satellite temperature datasets alluded to in the quoted testimony.
        This consistency between two independent datasets gathered using
    very different techniques gives us a high level of confidence that the
    UAH satellite dataset provides a reliable measure of global atmospheric
    temperatures over more than 90 percent of the globe. (By comparison,
    one of the most often quoted surface temperature datasets achieves
    partial-global coverage only by claiming that certain isolated
    thermometer sites provide representative temperatures for an area
    roughly equaling two-thirds of the contiguous 48 states, an area that
    would reach from about Brownsville, Texas, to Grand Forks, North
    Dakota.)
        5. A final point relates to numerous comments elsewhere in the
    testimony in which an appeal to a nebulous ``mainstream climate
    community'' was made to support what was stated. First, the notion that
    ``thousands'' of climate scientists agreed on the IPCC 2001 text is an
    illusion. I was a lead author of IPCC 2001, as was Dr. Mann. There were
    841 lead authors and contributors, the majority of whom were not
    climatologists and who provided input in the area in which they have
    expertise only to their tiny portion of the 800+ page document. These
    841 were not asked to approve nor where they given the opportunity to
    give a stamp of approval on what was finally published.
        Although I might be outside the ``mainstream,'' according to Dr.
    Mann's perspective, I have never thought a scientist's goal was to
    achieve membership in the ``mainstream.'' My goal is to produce the
    most reliable climate datasets for use in scientific research. Whether
    they show warming or cooling is less important to me than their
    reliability and accuracy. That these datasets have been published in
    numerous peer-reviewed venues is testimony to accomplishing this goal
    and, by inference, would place me inside the mainstream climate
    community. In addition to being an IPCC lead author, significant
    achievement awards from NASA and the American Meteorological Society
    along with my recent election as a Fellow of the AMS are evidence of my
    impact on the community of scientists.
        I hope this clears up any confusion you or your committee members
    might have had about the UAH global temperature data. If you or any of
    your committee members have any questions, I will be delighted to
    answer them to the best of my ability.
        Thank you again for offering me this opportunity. I remain,
                Sincerely,
                                    John Christy, Ph.D.