[House Hearing, 110 Congress]
[From the U.S. Government Publishing Office]



 
                THE STATE OF CLIMATE CHANGE SCIENCE 2007

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

                                HEARINGS

                               BEFORE THE

                  COMMITTEE ON SCIENCE AND TECHNOLOGY

                       ONE HUNDRED TENTH CONGRESS

                             FIRST SESSION

                               ----------                              

                 February 8, April 17, and May 15, 2007

                               ----------                              

                 Serial Nos. 110-2, 110-20, and 110-30

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     Printed for the use of the Committee on Science and Technology



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                  COMMITTEE ON SCIENCE AND TECHNOLOGY

                 HON. BART GORDON, Tennessee, Chairman
JERRY F. COSTELLO, Illinois          RALPH M. HALL, Texas
EDDIE BERNICE JOHNSON, Texas         F. JAMES SENSENBRENNER JR., 
LYNN C. WOOLSEY, California              Wisconsin
MARK UDALL, Colorado                 LAMAR S. SMITH, Texas
DAVID WU, Oregon                     DANA ROHRABACHER, California
BRIAN BAIRD, Washington              KEN CALVERT, California
BRAD MILLER, North Carolina          ROSCOE G. BARTLETT, Maryland
DANIEL LIPINSKI, Illinois            VERNON J. EHLERS, Michigan
NICK LAMPSON, Texas                  FRANK D. LUCAS, Oklahoma
GABRIELLE GIFFORDS, Arizona          JUDY BIGGERT, Illinois
JERRY MCNERNEY, California           W. TODD AKIN, Missouri
PAUL KANJORSKI, Pennsylvania         JO BONNER, Alabama
DARLENE HOOLEY, Oregon               TOM FEENEY, Florida
STEVEN R. ROTHMAN, New Jersey        RANDY NEUGEBAUER, Texas
MICHAEL M. HONDA, California         BOB INGLIS, South Carolina
JIM MATHESON, Utah                   MICHAEL T. MCCAUL, Texas
MIKE ROSS, Arkansas                  MARIO DIAZ-BALART, Florida
BEN CHANDLER, Kentucky               PHIL GINGREY, Georgia
RUSS CARNAHAN, Missouri              BRIAN P. BILBRAY, California
CHARLIE MELANCON, Louisiana          ADRIAN SMITH, Nebraska
BARON P. HILL, Indiana               VACANCY
HARRY E. MITCHELL, Arizona
CHARLES A. WILSON, Ohio
 The State of Climate Change Science 2007: The Findings of the Fourth 
  Assessment Report by the Intergovernmental Panel on Climate Change 
                     (IPCC), Working Group I Report

                            C O N T E N T S

                            February 8, 2007

                                                                   Page
Witness List.....................................................     2

Hearing Charter..................................................     3

                           Opening Statements

Statement by Representative Bart Gordon, Chairman, Committee on 
  Science and Technology, U.S. House of Representatives..........     7
    Written Statement............................................     8

Statement by Representative Ralph M. Hall, Minority Ranking 
  Member, Committee on Science and Technology, U.S. House of 
  Representatives................................................     9
    Written Statement............................................    11

Prepared Statement by Representative Jerry F. Costello, Member, 
  Committee on Science and Technology, U.S. House of 
  Representatives................................................    12

Prepared Statement by Representative Eddie Bernice Johnson, 
  Member, Committee on Science and Technology, U.S. House of 
  Representatives................................................    13

Prepared Statement by Representative Daniel Lipinski, Member, 
  Committee on Science and Technology, U.S. House of 
  Representatives................................................    13

Prepared Statement by Representative Mike Ross, Member, Committee 
  on Science and Technology, U.S. House of Representatives.......    13

Prepared Statement by Representative Russ Carnahan, Member, 
  Committee on Science and Technology, U.S. House of 
  Representatives................................................    14

Prepared Statement by Representative Harry E. Mitchell, Member, 
  Committee on Science and Technology, U.S. House of 
  Representatives................................................    14

Prepared Statement by Representative Vernon J. Ehlers, Member, 
  Committee on Science and Technology, U.S. House of 
  Representatives................................................    15

Prepared Statement by Representative Randy Neugebauer, Member, 
  Committee on Science and Technology, U.S. House of 
  Representatives................................................    15

                                Panel I:

The Honorable Nancy Pelosi, Speaker of the House of 
  Representatives
    Oral Statement...............................................    16
    Written Statement............................................    19

Discussion
  Economic Impacts of Climate Change.............................    21
  Select Committee on Energy Independence and Global Warming.....    22
  Nuclear Energy.................................................    23
  The International Banking Environmental Protection Act.........    24
  Question and Answer Session: Congressional Customs.............    25

                               Panel II:

Dr. Susan Solomon, Co-Chair, IPCC, Working Group I: The Physical 
  Basis of Climate Change; Senior Scientist, Earth System 
  Research Laboratory, Office of Oceanic and Atmospheric 
  Research, National Oceanic and Atmospheric Administration, U.S. 
  Department of Commerce
    Oral Statement...............................................    28
    Written Statement............................................    30
    Biography....................................................    46

Dr. Kevin E. Trenberth, Coordinating Lead Author, IPCC, Working 
  Group I, Chapter 3: Observations: Surface and Atmospheric 
  Climate Change; Head, Climate Analysis Section, National Center 
  for Atmospheric Research
    Oral Statement...............................................    46
    Written Statement............................................    49
    Biography....................................................    55

Dr. Richard B. Alley, Lead Author, IPCC, Working Group I, Chapter 
  4: Observations: Changes in Snow, Ice and Frozen Ground; Evan 
  Pugh Professor of Geosciences and Associate of the Earth and 
  Environmental Systems Institute, Pennsylvania State University
    Oral Statement...............................................    56
    Written Statement............................................    57
    Biography....................................................    61

Dr. Gerald A. Meehl, Coordinating Lead Author, IPCC, Working 
  Group I, Chapter 10: Global Climate Projections; Senior 
  Scientist, National Center for Atmospheric Research
    Oral Statement...............................................    61
    Written Statement............................................    63
    Biography....................................................    66

Discussion
  The IPCC Process...............................................    67
  Glacier Melt Accelerations.....................................    67
  Global Warming Trends..........................................    70
  More on the IPCC Process.......................................    73
  More on Global Warming Trends..................................    74
  Greenhouse Gas Production: Country Comparisons.................    77
  Climate Research...............................................    77
  Carbon Sequestration...........................................    79
  Advancements in Climate Research...............................    81
  Cooling in Antarctica..........................................    81
  Impact on the Western United States............................    81
  Thermal Expansion of Seawater..................................    82
  Mitigating Climate Change......................................    82
  Ocean Circulation Changes......................................    83
  Tropical Storms................................................    85
  Social and Economic Impacts of Climate Change..................    86
  More on the IPCC Process.......................................    86
  Global Impacts of Climate Change...............................    87
  Managing Water Resources.......................................    88
  More on Climate Research.......................................    89
  Opposition to Climate Change...................................    90
  Climate Change Scenarios.......................................    93
  More Climate Change Scenarios..................................    93
  Scientific Consensus...........................................    94
  Impact on the Southwestern United States.......................    96
  Regional vs. Global Modeling...................................    97
  U.S. Leadership in Mitigating Climate Change...................    98
  More on Climate Science........................................   100

              Appendix: Answers to Post-Hearing Questions

Dr. Susan Solomon, Co-Chair, IPCC, Working Group I: The Physical 
  Basis of Climate Change; Senior Scientist, Earth System 
  Research Laboratory, Office of Oceanic and Atmospheric 
  Research, National Oceanic and Atmospheric Administration, U.S. 
  Department of Commerce.........................................   106

Joint responses by Dr. Richard B. Alley, Lead Author, IPCC, 
  Working Group I, Chapter 4: Observations: Changes in Snow, Ice 
  and Frozen Ground; Evan Pugh Professor of Geosciences and 
  Associate of the Earth and Environmental Systems Institute, 
  Pennsylvania State University; Dr. Kevin E. Trenberth, 
  Coordinating Lead Author, IPCC, Working Group I, Chapter 3: 
  Observations: Surface and Atmospheric Climate Change; Head, 
  Climate Analysis Section, National Center for Atmospheric 
  Research; Dr. Gerald A. Meehl, Coordinating Lead Author, IPCC, 
  Working Group I, Chapter 10: Global Climate Projections; Senior 
  Scientist, National Center for Atmospheric Research; and Dr. 
  Susan Solomon, Co-Chair, IPCC, Working Group I: The Physical 
  Basis of Climate Change; Senior Scientist, Earth System 
  Research Laboratory, Office of Oceanic and Atmospheric 
  Research, National Oceanic and Atmospheric Administration, U.S. 
  Department of Commerce.........................................   107

 The State of Climate Change Science 2007: The Findings of the Fourth 
  Assessment Report by the Intergovernmental Panel on Climate Change 
   (IPCC), Working Group II: Climate Change Impacts, Adaptation and 
                             Vulnerability

                            C O N T E N T S

                             April 17, 2007

                                                                   Page
Witness List.....................................................   112

Hearing Charter..................................................   113

                           Opening Statements

Statement by Representative Bart Gordon, Chairman, Committee on 
  Science and Technology, U.S. House of Representatives..........   119
    Written Statement............................................   119

Statement by Representative Ralph M. Hall, Minority Ranking 
  Member, Committee on Science and Technology, U.S. House of 
  Representatives................................................   120
    Written Statement............................................   121

Prepared Statement by Representative Jerry F. Costello, Member, 
  Committee on Science and Technology, U.S. House of 
  Representatives................................................   122

Prepared Statement by Representative Nick Lampson, Chairman, 
  Subcommittee on Energy and Environment, Committee on Science 
  and Technology, U.S. House of Representatives..................   122

Prepared Statement by Representative Harry E. Mitchell, Member, 
  Committee on Science and Technology, U.S. House of 
  Representatives................................................   123

Prepared Statement by Representative Vernon J. Ehlers, Member, 
  Committee on Science and Technology, U.S. House of 
  Representatives................................................   123

                               Witnesses:

Dr. Cynthia Rosenzweig, Senior Research Scientist, NASA Goddard 
  Institute for Space Studies, The Earth Institute at Columbia 
  University
    Oral Statement...............................................   125
    Written Statement............................................   126
    Biography....................................................   130

Dr. William E. Easterling, Professor of Geography and Agronomy; 
  Director, Penn State Institutes of Energy and the Environment, 
  Pennsylvania State University
    Oral Statement...............................................   130
    Written Statement............................................   134
    Biography....................................................   137

Dr. Virginia Burkett, Chief Scientist for Global Change Research, 
  U.S. Geological Survey, U.S. Department of the Interior
    Oral Statement...............................................   138
    Written Statement............................................   143

Dr. Shardul Agrawala, Princeton University and Organisation for 
  Economic Co-operation and Development (OECD)
    Oral Statement...............................................   154
    Written Statement............................................   156
    Biography....................................................   158

Dr. Roger S. Pulwarty, Program Director, National Integrated 
  Drought Information System (NIDIS), Office of Oceanic and 
  Atmospheric Research, National Oceanic and Atmospheric 
  Administration, U.S. Department of Commerce
    Oral Statement...............................................   158
    Written Statement............................................   160
    Biography....................................................   164

Dr. Stephen H. Schneider, Melvin and Joan Lane Professor for 
  Interdisciplinary Environmental Studies; Professor, Department 
  of Biological Sciences; Senior Fellow, Center for Environmental 
  Science and Policy at the Woods Institute for the Environment, 
  Stanford University
    Oral Statement...............................................   165
    Written Statement............................................   170
    Biography....................................................   179

Discussion
  Dangerous Anthropogenic Interference...........................   180
  Potential Mitigation of Climate Change.........................   181
  Climate Change Impacts.........................................   181
  Anthropogenic Causes of Climate Change.........................   181
  Climate Change Impacts: Drought................................   182
  Climate Change Impacts: The Great Lakes........................   183
  Carbon Sinks...................................................   184
  Impacts on the Fishing Industry................................   184
  Energy Concerns................................................   186
  International Efforts..........................................   187
  Adaptation and Mitigation Strategies...........................   189
  Climate Change Impacts: Agriculture............................   191
  Climate Change Impacts: Water Availability.....................   191
  Climate Change Impacts: Coastal Louisiana......................   194
  Air Indexing in Third World Countries..........................   196
  Global Dimming.................................................   197
  Climate Change Impacts: Southern Arizona.......................   198
  Sunspots.......................................................   199
  Sea Walls......................................................   201
  The IPCC Process...............................................   201

             Appendix 1: Answers to Post-Hearing Questions

Dr. Cynthia Rosenzweig, Senior Research Scientist, NASA Goddard 
  Institute for Space Studies, The Earth Institute at Columbia 
  University.....................................................   206

Dr. Virginia Burkett, Chief Scientist for Global Change Research, 
  U.S. Geological Survey, U.S. Department of the Interior........   208

Dr. Roger S. Pulwarty, Physical Scientist, Climate Program 
  Office, Office of Oceanic and Atmospheric Research, National 
  Oceanic and Atmospheric Administration, U.S. Department of 
  Commerce.......................................................   212

Dr. Stephen H. Schneider, Melvin and Joan Lane Professor for 
  Interdisciplinary Environmental Studies; Professor, Department 
  of Biological Sciences; Senior Fellow, Center for Environmental 
  Science and Policy at the Woods Institute for the Environment, 
  Stanford University............................................   217

             Appendix 2: Additional Material for the Record

More Trees, Less Global Warming, Right?--Not Exactly, Scientific 
  American, April 10, 2007.......................................   222

Why So Gloomy?, by Richard S. Lindzen, Special to Newsweek, April 
  16, 2007.......................................................   224

 The State of Climate Change Science 2007: The Findings of the Fourth 
  Assessment Report by the Intergovernmental Panel on Climate Change 
        (IPCC), Working Group III: Mitigation of Climate Change

                            C O N T E N T S

                              May 16, 2007

                                                                   Page
Witness List.....................................................   228

Hearing Charter..................................................   229

                           Opening Statements

Statement by Representative Bart Gordon, Chairman, Committee on 
  Science and Technology, U.S. House of Representatives..........   237
    Written Statement............................................   238

Statement by Representative Ralph M. Hall, Ranking Minority 
  Member, Committee on Science and Technology, U.S. House of 
  Representatives................................................   238
    Written Statement............................................   240

Prepared Statement by Representative Jerry F. Costello, Member, 
  Committee on Science and Technology, U.S. House of 
  Representatives................................................   241

Prepared Statement by Representative Eddie Bernice Johnson, 
  Member, Committee on Science and Technology, U.S. House of 
  Representatives................................................   241

                               Witnesses:

Dr. Mark D. Levine, Division Director of the Environmental Energy 
  Technology Division at Lawrence Berkeley Laboratory
    Oral Statement...............................................   242
    Written Statement............................................   244
    Biography....................................................   247

Dr. William A. Pizer, Fellow at Resources for the Future and 
  Senior Economist at the National Commission on Energy Policy
    Oral Statement...............................................   247
    Written Statement............................................   250
    Biography....................................................   259

Mr. Steven E. Plotkin, Transportation Energy Analyst with the 
  Center of Transportation Research at the Argonne National 
  Laboratory
    Oral Statement...............................................   260
    Written Statement............................................   262
    Biography....................................................   265

Dr. Roger A. Pielke, Jr., Professor of Environmental Studies 
  Program at the University of Colorado and Director of the 
  Center for Science and Technological Policy Research
    Oral Statement...............................................   265
    Written Statement............................................   270
    Biography....................................................   280

Discussion
  Biofuels.......................................................   280
  Fuel Economy Standards in China................................   280
  International Efforts..........................................   281
  The Advanced Research Projects Agency-Energy (ARPA-E)..........   282
  Adaptation and Mitigation Strategies...........................   282
  The IPCC Process...............................................   283
  Adaptation and Mitigation Strategies in China..................   284
  Green Employment Opportunities.................................   285
  Building Efficiency............................................   285
  More on International Efforts..................................   286
  Efficiency Technologies........................................   288
  More on Building Efficiency....................................   289
  Anthropogenic Causes of Climate Change.........................   290
  Mitigation Obstacles...........................................   292
  Mitigation Costs...............................................   293
  Developing Countries...........................................   294
  More on Building Efficiency....................................   294
  China's Coal Energy Production.................................   295
  Energy Efficiency Priorities...................................   297
  Nuclear Energy.................................................   299
  Future IPCC Reports............................................   301

              Appendix: Answers to Post-Hearing Questions

Dr. Mark D. Levine, Division Director of the Environmental Energy 
  Technology Division at Lawrence Berkeley Laboratory............   304

Dr. William A. Pizer, Fellow at Resources for the Future and 
  Senior Economist at the National Commission on Energy Policy...   306

Mr. Steven E. Plotkin, Transportation Energy Analyst with the 
  Center of Transportation Research at the Argonne National 
  Laboratory.....................................................   310

Dr. Roger A. Pielke, Jr., Professor of Environmental Studies 
  Program at the University of Colorado and Director of the 
  Center for Science and Technological Policy Research...........   314


 THE STATE OF CLIMATE CHANGE SCIENCE 2007: THE FINDINGS OF THE FOURTH 
  ASSESSMENT REPORT BY THE INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE 
                     (IPCC), WORKING GROUP I REPORT

                              ----------                              


                       THURSDAY, FEBRUARY 8, 2007

                  House of Representatives,
                       Committee on Science and Technology,
                                                    Washington, DC.

    The Committee met, pursuant to call, at 10:00 a.m., in Room 
2318 of the Rayburn House Office Building, Hon. Bart Gordon 
[Chairman of the Committee] presiding.


                            hearing charter

                  COMMITTEE ON SCIENCE AND TECHNOLOGY

                     U.S. HOUSE OF REPRESENTATIVES

               The State of Climate Change Science 2007:

                 The Findings of the Fourth Assessment

                 Report by the Intergovernmental Panel

                       on Climate Change (IPCC),

                         Working Group I Report

                       thursday, february 8, 2007
                         10:00 a.m.-12:00 p.m.
                   2318 rayburn house office building

Purpose

    On February 8, 2007, the Committee on Science and Technology will 
hold a hearing on the first section of the 2007 Assessment Report, 
Climate Change 2007: The Physical Science Basis of Climate Change, 
prepared by Working Group I of the Intergovernmental Panel on Climate 
Change (IPCC). Released in Paris, France, on February 2, 2007, this 
document presents a comprehensive appraisal of the current state of 
scientific knowledge of climate change.
    The Committee will hear testimony from four witnesses who were 
involved in the preparation of the Working Group I Report. The 
witnesses will present the findings of the Report and discuss the 
relationship between the current findings and those of past IPCC 
reports on the state of climate change science.

Key Findings of the 2007 Working Group I Report

    On February 2, 2007 the Intergovernmental Panel on Climate Change 
(IPCC) released the first section of its Fourth Assessment Report, 
entitled ``The Physical Science Basis of Climate Change.''
    This first section of the IPCC Fourth Assessment Report builds upon 
information contained in the previous reports. It updates information 
from the Third Assessment Report based upon research conducted over the 
past six years. Uncertainties in some areas have been reduced (e.g., 
quantitative estimates of radiative forcing). Climate models have 
improved, and expanded observations, data and information have enabled 
the IPCC to increase the level of confidence in some earlier findings 
(e.g., attribution of warming to human-induced increases in greenhouse 
gas concentrations). In other areas (e.g., changes in frequency of 
tropical cyclones) uncertainties remain and further research is needed 
to determine what patterns, if any, exist.
    Despite remaining uncertainties, the Fourth Assessment Report 
represents a significant expansion in our knowledge of the influence of 
human activity on the Earth's climate. It is almost 30 years since the 
first international scientific conference on climate suggested that 
human activity could be impacting the Earth's climate. This report 
confirms the original suspicions raised by scientists participating in 
the 1979 climate conference as has every report of the IPCC from the 
first report in 1990 to the present.
    The 10 key findings in the 2007 report are:

          Atmospheric concentrations of greenhouse gases have 
        increased significantly due to human activities since 1750 due 
        to fossil fuel use and land-use change.

          Our understanding of human-induced influences on 
        climate has improved since the 2001 Assessment. There is now 
        very high confidence that Earth is warming.

          Evidence that Earth is warmer includes: increase in 
        global average air temperature and ocean temperature, 
        widespread melting of snow and ice, and rising global average 
        sea level.

          Long-term changes in climate have been observed 
        including: changes in Arctic temperatures and ice, changes in 
        the amounts of precipitation, ocean salinity, and wind patterns 
        and changes in extreme weather events such as droughts, heavy 
        precipitation, heat waves, and intensity of hurricanes and 
        typhoons.

          Changes in diurnal temperature ranges, Antarctic sea 
        ice extent, meridional overturning circulation of the global 
        ocean, and localized extreme weather events such as tornadoes, 
        lightning, and dust storms have not been observed.

          The interpretation that the warming of the last 50 
        years is unusual in at least the previous 1,300 years is 
        consistent with paleoclimate information. During the last 
        period when polar regions were significantly warmer than 
        present for an extended period of time (about 125,000 years 
        ago), reduced volume of polar ice led to sea level rise of four 
        to six meters.

          Most of the observed increase in globally averaged 
        temperatures since the mid-twentieth century is very likely due 
        to the observed increase in anthropogenic greenhouse gas 
        concentrations. Discernible human influences now extend to 
        other aspects of climate, including ocean warming, continental-
        average temperatures, temperature extremes and wind patterns.

          Analysis of climate models coupled with constraints 
        of observations enables an assessed likely range to be given 
        for climate sensitivity for the first time and provides 
        increased confidence in the understanding of the climate system 
        response to radiative forcing. The likely global average 
        surface warming associated with a doubling of CO2 
        concentration is in the range 2 to 4.5+C. It is very 
        unlikely that climate changes of at least the seven centuries 
        prior to 1950 were due to variability generated within the 
        climate system alone.

          For the next 20 years a warming of 0.2+C 
        per decade is projected for a range of emission scenarios. Even 
        if the concentrations of all greenhouse gases and aerosols had 
        been kept constant at year 2000 levels, a further warming of 
        about 0.1+C per decade would be expected.

          Continued greenhouse gas emissions at or above 
        current rates would cause further warming and induce many 
        changes in the global climate system during the twenty-first 
        century that would very likely be larger than those observed 
        during the twentieth century.

Background

    Prior to the establishment of the IPCC, the World Meteorological 
Organization (WMO) convened two international meetings on greenhouse 
gas emissions and global climate. In 1979, the first World Climate 
Conference issued the following concern: ``continued expansion of man's 
activities on Earth may cause significant extended regional and even 
global changes in climate.'' In 1985 the United Nations Environment 
Program (UNEP), WMO, and the International Council for Science (ICSU) 
organized a joint conference on the ``Assessment of the Role of Carbon 
Dioxide and of Other Greenhouse Gases in Climate Variations and 
Associated Impacts.'' This conference concluded that ``as a result of 
the increasing greenhouse gases it is now believed that in the first 
half of the next century (twenty-first century) a rise of global mean 
temperature could occur which is greater than in any man's history.''
    In response to the findings of these earlier conferences, the IPCC 
was created by WMO and UNEP in 1988. The IPCC was created to provide 
assessments of scientific, technical and socio-economic information 
relevant to understanding the risk of human-induced climate change, its 
potential impacts and options for adaptation and mitigation.
    The IPCC is organized into a Plenary which meets once a year and is 
attended by officials and experts from relevant ministries, agencies, 
and research institutions from member countries and from participating 
organizations. This body makes the decisions about preparation of new 
reports, their scope and content, and accepts reports prepared by 
expert teams. It elects the IPCC Chair, currently Rajendra K. Pachauri, 
and the members of the IPCC Bureau. It also establishes IPCC principles 
and procedures, designs the work plan and budget for the Panel and its 
activities. The IPCC Secretariat is located in Geneva, Switzerland.
    The IPCC relies upon primarily peer reviewed, published scientific 
and technical literature. The IPCC also prepares special reports and 
technical papers on topics where independent scientific information and 
advice is deemed necessary. The panel operates within extensive peer 
review and governmental review, thus ensuring a high level of 
transparency, scientific credibility, and policy relevance. Hundreds of 
experts from around the world contribute to the assessment reports as 
authors, contributors, and reviewers. Participants are selected by the 
members of the IPCC Bureau (30 members each from a different nation) 
who are all elected for five to six years and who are all experts in 
climate change. Participants may be nominated by governments or 
participating organizations or they may be chosen due to their 
recognized expertise.
    The IPCC published the First Assessment Report in 1990, 
Supplementary Reports in 1992, a Special Report in 1994, a Second 
Assessment Report (SAR) in 1995, and a Third Assessment Report (TAR) in 
2001. Each of the assessment reports are comprised of three volumes 
from three corresponding working groups (I, II and III).
First Assessment Report
    The First IPCC Assessment Report was completed in 1990 and provided 
policy-makers with a comprehensive assessment of what was then known, 
and not known, about human influence on climate. The report provided 
the main scientific basis for the negotiation of the Framework 
Convention on Climate Change (UNFCCC). The 1992 United Nations 
Framework Convention on Climate Change was ratified by the United 
States and called for a ``non-binding,'' voluntary goal for 
industrialized countries to stabilize their emissions of greenhouse 
gases at 1990 levels by the year 2000.
    The 1990 IPCC report, as well as two Supplementary Reports (1992 
and 1994) supplied critical information for the United Nations 
Conference on Environment and Development in Rio de Janeiro in June 
1992. The Convention went into effect in March 1994 and the first 
session of the Conference of the Parties (COP) was held in Berlin in 
April 1995.
    In the 1990 assessment, the authors' wrote, ``The size of the 
warming is broadly consistent with predictions of climate models, . . 
.but the unequivocal detection of the enhanced greenhouse effect from 
observations is not likely for a decade or more.'' The report projected 
an increase in average global temperature during the twenty-first 
century of 0.3 degrees Celsius per decade and discussed the possible 
consequences of that temperature change in relation to rising sea 
levels, increase in extreme weather events, and serious pressure on 
aquatic and terrestrial ecosystems.
Second Assessment Report
    Completed in 1995, the Second IPCC Assessment Report expanded on 
the findings of the 1990 assessment. The Second Assessment Report 
stated that the climate of the Earth had changed over the past century, 
increasing the global mean surface air temperature somewhere between 
0.3 and 0.6 degrees Celsius. The report stated that climate was 
expected to change further in the future and projected an increase of 
1.0 to 3.5 degrees Celsius by 2100.
    In the 1995 report, the IPCC concluded that ``. . .the balance of 
evidence suggests that there is a discernible human influence on global 
climate.'' This second assessment provided key input to the 
negotiations that led to the adoption of the Kyoto Protocol in 1997. 
More than 160 nations, parties to the Framework Convention on Climate 
Change, adopted the Kyoto Protocol, with legally binding obligations to 
limit emissions of industrialized nations for the years 2008 to 2012. 
The Protocol's emissions targets are hailed as important first steps 
toward the Framework Convention's objective of avoiding dangerous 
climate change.
Third Assessment Report
    The Third Assessment Report, ``Climate Change 2001'' consisted of 
three working group reports on ``The Scientific Basis,'' ``Impacts, 
Adaptation and Vulnerability,'' and ``Mitigation.'' The findings also 
contained a synthesis report, which addressed a range of policy 
relevant scientific and technical questions. This third report 
emphasized the findings from the previous five years and projected that 
average global temperature would rise from 1.4 to 5.8 degrees Celsius 
over the next century. In addition, authors explained how precipitation 
patterns are expected to change, the degree to which sea level is 
expected to rise, and the possibility of the increases in extreme 
weather events.
    By the release of the 2001 report, confidence in the ability of 
models to project future climate increased and authors concluded, 
``There is new and stronger evidence that most of the warming observed 
over the last 50 years is attributable to human activities.'' 
Furthermore, extensive and wide-spread evidence is present 
demonstrating that the Earth is warming and clear signals of a changing 
climate exist.

Witnesses

Dr. Susan Solomon of the National Oceanic and Atmospheric 
Administration (NOAA):

    Dr. Susan Solomon serves as Co-Chair of Working Group I of the 
Intergovernmental Panel on Climate Change (IPCC), providing scientific 
information to the United Nations Framework Convention on Climate 
Change. Her current research includes climate change and ozone 
depletion, and she served as an overall coordinator for the report. 
After receiving her Ph.D. in chemistry from the University of 
California at Berkeley in l98l, she has been employed by the National 
Oceanic and Atmospheric Administration as a research scientist. Her 
scientific papers have provided not only key measurements but also 
theoretical understanding regarding ozone destruction, especially the 
role of surface chemistry.
    Dr. Solomon will provide an overview of the key findings of the 
report. Working Group I's contribution to the Fourth Assessment Report 
includes 11 chapters. Each chapter has two Coordinating Lead Authors 
who are responsible for pulling together the material for the chapter. 
In addition to the Coordinating Lead Authors, there are a number of 
Lead Authors as well as numerous contributors and reviewers associated 
with each chapter.
    Each of the other IPCC authors, Dr. Trenberth, Dr. Alley, and Dr. 
Meehl will discuss the findings with a focus on their respective 
chapters.

Dr. Kevin Trenberth of the National Center for Atmospheric Research 
(NCAR):

    Dr. Kevin Trenberth served as a Coordinating Lead Author for 
Chapter 3 of the report entitled: Observations: Surface and Atmospheric 
Climate Change. Currently, Dr. Trenberth is Head of the Climate 
Analysis Section at the National Center for Atmospheric Research (NCAR) 
in Boulder, Colorado. From New Zealand, he completed his undergraduate 
degree in mathematics at the University of Canterbury, Christchurch, 
New Zealand, and obtained his Sc.D. in meteorology in 1972 from 
Massachusetts Institute of Technology, Cambridge, Massachusetts.

Dr. Richard Alley of the Department of Geosciences, Pennsylvania State 
University:

    Dr. Richard Alley served as a Lead Author for Chapter 4 of the 
report entitled: Observations: Changes in Snow, Ice, and Frozen Ground. 
Dr. Alley is Evan Pugh Professor of Geosciences and Associate of the 
Earth and Environmental Systems Institute at The Pennsylvania State 
University, University Park, where he has worked since 1988. He 
received his Ph.D. in 1987 from the University of Wisconsin-Madison and 
his M.Sc. (1983) and B.Sc. (1980) degrees from The Ohio State 
University-Columbus, all in Geology. Dr. Alley teaches, and conducts 
research on the climatic records, flow behavior, and sedimentary 
deposits of large ice sheets, to aid in prediction of future changes in 
climate and sea level.

Dr. Gerald Meehl of the National Center for Atmospheric Research 
(NCAR):

    Dr. Meehl is a Coordinating Lead Author for Chapter 10 of the 
report: Global Climate Projections. Dr. Meehl received his Ph.D. in 
Climate Dynamics from the University of Colorado in 1987. His expertise 
is in the field of climate modeling. He has been a scientist on staff 
at NCAR since 1979. He has been a member of the Working Group I Report 
Group since 1989 and has participated in the development of previous 
IPCC assessment reports.

Definitions:

Radiative forcing--an external disturbance in the radiative energy 
budget of Earth's climate system brought about by changes in 
atmospheric concentrations of greenhouse gases, changes in solar 
radiation, or changes in the surface reflective properties of Earth.

Meridional overturning circulation--the circulation system of the 
world's oceans driven by variations in temperature and salinity. Cold, 
dense water formed in polar oceans sinks and is replaced by warmer, 
less dense surface water from temperate latitudes.
    Chairman Gordon. Well, good morning, and welcome to this 
hearing on the Intergovernmental Panel on Climate Change, or 
IPCC, Report on the current state of our knowledge on climate 
change.
    This is the first opportunity Congress has to examine the 
findings of this important report.
    The first warnings about the potential for climate change 
came in 1979 when the first international conference on climate 
change expressed the concern that human activity might lead to 
significant regional and global changes in climate.
    Now, almost 30 years later, increasing evidence confirms 
this warning is real.
    The importance of this report cannot be overstated. The 
Report provides overwhelming evidence that global warming is 
real and that human activity is the driving force.
    The Report's findings may be alarming, but it is not the 
work of alarmists. The Report's findings were endorsed 
unanimously by the representatives of 113 nations, including 
the United States, and it is the product of the work of nearly 
300 scientists. In short, this is a unanimous, definitive 
statement that global warming is real and it is very likely 
that humans have contributed to it.
    And let me just make that clear. This is a unanimous, 
definitive statement. That meant that every nation, every 
scientist had to agree to that. And so the Nation that might be 
the most naysaying, the scientists that might be the most 
skeptical still had to agree to this Report. So, at a minimum, 
this is a conservative report about climate change.
    The scientific experts have provided us with a diagnosis of 
the problem and a prognosis for our nation's health. If we 
continue along our current path, the prognosis is ominous.
    The scientists have done their job. Now, it is time for us, 
the policy-makers, to do ours.
    We face a big challenge. We must explore ways to reduce 
emissions, to adapt to coming changes, and to mitigate the 
negative effects of climate change. We cannot accomplish all 
this overnight, but we must begin in earnest now to address 
this serious issue. And with some bit of irony, today, the 
Science Committee has a bill of mine on the Floor in about an 
hour that will be the first bill that will address renewable 
energy. We hope it will be--we don't hope, we know it will be 
the first of many bills.
    The IPCC Report tells us that if we fail to act, our 
children, my five-year old daughter, Dana's triplets, Brian's 
twins, and Madame Speaker, your little four-month-old son, or 
grandson--you look wonderful--they are all going to be 
affected, and they are going to live in a very different world. 
And let me just say, this is not hypothetical. When you start 
talking about 10 years, 20 years, 50 years, maybe 100 years, it 
seems like it is a long time off, but the actuaries tell us 
that our children are all going to live to the end of this 
century. And certainly, our grandchildren are going to live 
beyond that. So this is real. This is not hypothetical. We are 
talking about something that is going to affect all of us in a 
very personal way, because they are going to inherit a world 
which has much more severe droughts in some regions, greater 
flooding in others, and very different coastlines due to a 
higher sea level.
    And two days ago, my daughter spent the afternoon in my 
office. We were looking out at the Capitol and I am hoping that 
when she is older she is going to remember that view.
    And I don't want to look in my daughter's eyes in 10 or 20 
years and try to explain why I didn't take advantage of the 
opportunity to address global warming while I was in Congress.
    We need to improve existing technologies and to develop new 
technologies and to reduce emissions and to make our economy 
and our society more energy efficient. And we must understand 
the impacts of climate change on our ecosystems that support 
all life on Earth.
    Continued scientific research is imperative. We need 
better, more refined regional assessments to understand the 
climatic vulnerabilities of communities, ecosystems, and our 
economy. We must continue to gather information on greenhouse 
gas emissions and the Earth's response to them and to further 
expand our understanding of climate and weather.
    These four eminent scientists are a select few representing 
the efforts of thousands of scientists from all over the world. 
And as I said earlier, they have done their job. They have set 
the scientific information before us. We must now move forward 
and act upon this information.
    We, on the Science and Technology Committee, can and must 
play a role by ensuring that the science and research continue 
to provide us the information we need to understand climate 
change and to respond to it.
    However, we must also begin with the information and tools 
in hand today to adapt to the changing climate and to buy 
ourselves time to adapt and to innovate by reducing emissions 
and energy use.
    We are world leaders in science and innovation. I intend 
for this committee to ensure we maintain that leadership and 
lead the world to address it with us.
    On behalf of the Committee, I want to thank all of our 
witnesses for joining us today and for the work you have done 
in preparing this paper.
    [The prepared statement of Chairman Gordon follows:]
               Prepared Statement of Chairman Bart Gordon
    Good morning and welcome to this hearing on the Intergovernmental 
Panel on Climate Change (IPCC) report on the current state of our 
knowledge on climate change.
    This is the first opportunity Congress has to examine the findings 
of this important report.
    The first warning about the potential for climate change came in 
1979 when the first international conference on climate change 
expressed the concern that human activity might lead to significant 
regional and global changes in climate.
    Now, almost 30 years later increasing evidence confirms this 
warning is real.
    The importance of this report cannot be overstated.
    The Report provides overwhelming evidence that global warming is 
real and that human activity is driving this change.
    The Report's findings may be alarming, but it is not the work of 
alarmists.
    The Report's findings were endorsed unanimously by the 
representatives of 113 countries, including the United States.
    And is the product of the work of nearly 600 scientists.
    In short, it is a unanimous, definitive statement that global 
warming is real and that it is very likely humans have contributed to 
it.
    The scientific experts have provided us with a diagnosis of the 
problem and a prognosis for our planet's health. If we continue along 
our current path, the prognosis is ominous.
    The scientists have done their job. Now, it is time for us--the 
policy-makers--to do ours.
    We face a big challenge. We must explore ways to reduce emissions, 
to adapt to coming changes, and to mitigate the negative effects of a 
changing climate.
    We cannot accomplish all this overnight, but we must begin in 
earnest now to address this serious issue.
    The IPCC Report tells us that, if we fail to act, our children--my 
five-year-old daughter, Dana's triplets, and Brian's twins--will live 
in a much different world.
    A world with more severe droughts in some regions and greater 
flooding in others. And much different coastlines due to a higher sea 
level.
    Two days ago, my daughter spent the afternoon with me in my office. 
We were looking out at the Capitol and I am hoping that when she is 
older, she will remember that view.
    I don't want to look in my daughter's eyes in 10 or 20 years and 
try to explain why I didn't take advantage of an opportunity to address 
global warming while I was in Congress.
    We need to improve existing technologies and to develop new 
technologies to reduce emissions and make our economy and society more 
energy efficient.
    And we must understand the impacts of climate change on the 
ecosystems that support all life on Earth.
    Continued scientific research is imperative. We need better, more 
refined regional assessments to understand the climatic vulnerabilities 
of communities, ecosystems, and our economy.
    We must continue to gather information on greenhouse gas emissions 
and the Earth's response to them to further expand our understanding of 
climate and weather.
    These four eminent scientists are a select few representing the 
efforts of thousands of scientists from around the world. As I said 
earlier--they have done their job. They have set the scientific 
information before us. We must now move forward and act upon this 
information.
    We, on the Science and Technology Committee can and must play a 
role by ensuring that the science and research continue to provide us 
the information we need to understand climate change and to respond to 
it.
    However, we must also begin with the information and tools in hand 
today to adapt to the changing climate and to buy ourselves time to 
adapt and innovate by reducing emissions and energy use.
    We are world leaders in science and innovation. I intend to ensure 
this committee works to ensure we maintain that leadership. I believe 
we can meet this challenge and we can, and should, lead the world to 
address it with us.
    On behalf of the Committee, I want to thank all of our witnesses 
for agreeing to come before us this morning. I believe most of you have 
just returned from the meeting in Paris. We appreciate the work you 
have done and your willingness to appear today.

    Chairman Gordon. And at this time, I will recognize our 
very distinguished Ranking Member, Mr. Hall, for an opening 
statement.
    Mr. Hall. Good morning. And I thank you, and I thank the 
Chairman for organizing this hearing about the very important 
topic of global warming, or as some prefer to call it, climate 
change.
    Let me start by thanking all of the witnesses for being 
here today. This will be a key issue in the 110th Congress, and 
I hope that I speak for all of the Committee Members in saying 
that we appreciate the time that you all give us. Madame 
Speaker, we appreciate your appearing before us. I was amazed 
at the crowds outside there. At my age, I was fearful that 
someone had discovered I might have been one of the Lindbergh 
kidnappers. I didn't know what everybody was doing there. But 
you are all welcome. I see Sherry Boehlert, our former 
Chairman, in attendance, a great leader and a man that gave 
much of his time to this committee, and to this Congress, and 
to this nation. Thank you, Sherry.
    There will be a lot of debate in this Congress about what 
policies the United States should adopt to deal with the 
potential impacts of climate change. While today's hearing is 
focused primarily on the latest science related to climate 
change, it also is a public forum, and I expect Members will 
stray from the science and offer their opinions on various 
policy options that have been proposed.
    So in that vein, let me set the record straight from the 
beginning. I am skeptical about mandatory regulation of 
greenhouse gases, which some of my colleagues are promoting as 
the best solution to the problem of climate change.
    As a nation, we can't figure out how to write a cap-and-
trade bill that does not cause an immediate spike in natural 
gas prices, a spike that endures for several years at the very 
least. The result would be the closing of more factories, the 
closing of steel mills, paper mills, lumber mills, and many 
others. Gas price increases over the last six years, even 
without carbon regulation, have already caused millions of 
permanent layoffs. Factories won't compete with utilities to 
buy gas. Rather, they will move to China and India where there 
are no pollution controls, inevitably worsening global 
emissions. In the meantime, Americans will be paying the price.
    Clearly, we need to make the American people fully aware of 
the cost of mandatory emission caps. The discussion of 
mandatory caps comes down to one question: what is the maximum 
cost to the U.S. economy in dollars per family in a global 
warming bill, and what is the minimum effect on world-wide 
temperatures our country is willing to accept at such cost?
    Of course, in order to fully answer that question, we will 
need to factor into the equation the contribution, or lack of 
contribution, of those countries who produce much of the 
pollution problems and seem unwilling to be a part of the 
solution. I would like to see this committee address this 
important equation in the near future.
    We have an historic opportunity to use American innovation 
to help address the problem, and our committee is poised to 
offer competitive solutions. I would like to see more 
discussions on how technology, especially alternative energy 
technologies, can help address the issue of energy independence 
and climate change. I would also like to explore how we can 
encourage the development of technologies to use existing 
domestic resources more cleanly, effectively, and efficiently. 
In fact, later this morning, we will be considering an 
alternative energy technology bill on the House Floor. There is 
no limit to American innovation. When we put our minds to 
solving a problem, we find answers that not only benefit our 
country, but also the world. We have always been leaders in 
technology. This should be no exception. I would like to see 
this committee promote the development of a wide range of new 
technologies to help America become energy independent while 
maintaining our competitive edge in the world economy. In the 
end, innovation can do a lot, but only so much. World powers 
must absolutely do their part. Without this, there can be no 
true success in solving the problem of global warming.
    I look forward to hearing from our witnesses today and 
yield back my time.
    [The prepared statement of Mr. Hall follows:]
           Prepared Statement of Representative Ralph M. Hall
    Good morning. I am glad the Chairman organized this hearing about 
the important topic of global warming, or as some prefer to call it, 
climate change. Let me start by thanking all of the witnesses for being 
here today. This will be a key issue in the 110th Congress and I hope I 
speak for all the Committee Members in saying we appreciate your time 
and the expertise that you can provide to our discussions.
    There will be much debate this Congress about what policies the 
United States should adopt to deal with the potential impacts of 
climate change. While today's hearing is focused primarily on the 
latest science related to climate change, it is also a public forum and 
I expect Members will stray from the science and offer their own 
opinions on various policy options that have been proposed. So, in that 
vein, let me set the record straight from the beginning. I aim 
skeptical that mandatory regulation of greenhouse gasses, which some of 
my colleagues are promoting, is the best solution to the problem of 
climate change.
    As a nation, we can't figure out how to write a cap-and-trade bill 
that does not cause an immediate spike in natural gas prices--a spike 
that endures for several years at the very least. The result will be 
the closing of more factories--steel, paper, lumber and many others. 
Gas price increases over the last six years, even without carbon 
regulation, have already caused millions of permanent lay-offs. 
Factories won't compete with utilities to buy gas. Rather, they will 
move to China and India where there are no pollution controls, 
inevitably worsening global emissions. In the meantime, Americans will 
pay the price.
    Clearly, we need to make the American people fully aware of the 
costs of mandatory emission caps. The discussion of mandatory caps 
comes down to one question--What is the maximum cost to the U.S. 
economy (in dollars per family) in a global warming bill, and what is 
the minimum effect on worldwide temperature our country is willing to 
accept at such cost? Of course, in order to fully answer that question, 
we will need to factor into the equation the contribution, or lack of 
contribution, of those countries who produce much of the pollution 
problems and seem unwilling to be a part of the solution. I would like 
to see this committee address this important equation in the near 
future.
    We have an historic opportunity to use American innovation to help 
address this problem, and our committee is poised to offer competitive 
solutions. I would like to see more discussion of how technology, 
especially alternative energy technologies, can help address the issue 
of energy independence and climate change. I would also like to explore 
how we can encourage the development of technologies to use existing 
domestic resources more cleanly, effectively, and efficiently. In fact, 
later this morning we will consider an alternative energy technology 
bill on the House Floor. There is no limit to American innovation. When 
we put our minds to solving a problem, we find answers that not only 
benefit our country, but also the world. We have always been leaders in 
technology--this should be no exception. I would like to see this 
committee promote the development of a wide range of new technologies 
to help America become energy independent while maintaining our 
competitive edge in the world economy. In the end, innovation can do a 
lot, but only so much. World powers must absolutely do their part. 
Without this, there can be no true success in solving the problem of 
global warming.
    I look forward to hearing from our witnesses today and yield back 
the balance of my time.

    Mr. Sensenbrenner. Mr. Chairman, I have a parliamentary 
inquiry.
    Chairman Gordon. The gentleman from Wisconsin.
    Mr. Sensenbrenner. My parliamentary inquiry, Mr. Chairman, 
is are all of the witnesses that will appear today, including 
the distinguished Speaker, going to be subjected to questioning 
under the five-minute rule, as required by House Rule 11?
    Chairman Gordon. The gentleman raises a good question, but 
I will excuse the Speaker after her opening remarks.
    Mr. Sensenbrenner. A further parliamentary inquiry. Is the 
Chair aware that House Rule XI 2.(j)(2)(A) reads as follows: 
``Subject to subdivisions B and C, each Committee shall apply 
the five-minute rule during the questioning of witnesses and 
the hearing until such time as each Member of the Committee, 
who so desires, has had an opportunity to question each 
witness.''
    Chairman Gordon. I am aware of it, and I ask unanimous 
consent that the Speaker be allowed to leave after her opening 
statement.
    Mr. Sensenbrenner. Mr. Chairman, I object, and I request 
that House Rule 11, as cited, be applied, because it is 
mandatory.
    Chairman Gordon. As the gentleman knows, anything can be 
waived by unanimous consent.
    Mr. Sensenbrenner. Mr. Chairman, I object.
    Chairman Gordon. Well, if that is your choice, then you 
will be able to do that, and I am sure that the Speaker will 
give you a very good answer.
    Thank you, Mr. Hall. And Sherry Boehlert, as you can see, 
things still don't always change around here, but we welcome 
you back. And you prove that you can come home, and that we are 
very glad you are here.
    I ask unanimous consent that all additional opening 
statements submitted by the Committee Members be included in 
the record. Without objection, so ordered.
    [The prepared statement by Mr. Costello follows:]
         Prepared Statement of Representative Jerry F. Costello
    Good morning. I want to thank the witnesses for appearing before 
our committee to discuss the first section of the 2007 assessment 
report, Climate Change 2007: The Physical Science Basis of Climate 
Change, prepared by the Working Group I of the Intergovernmental Panel 
on Climate Change. This is a sobering report that demands our attention 
and I commend Chairman Gordon for moving quickly to hold today's 
hearing.
    This report gives the Congress added momentum to take meaningful 
action to combat global warming, and I look forward to working with my 
colleagues as we craft such legislation. This process needs to be one 
of consensus, taking a wide view of our current energy realities as 
well as the goals we need to reach in the future. As the Working 
Group's report states, ``continued greenhouse gas emissions at or above 
the current rates will cause further warming causing changes in the 
global climate system.'' Given the current state of scientific 
knowledge of climate change and prior reports based upon six years of 
research, we need to work together to find responsible solutions to 
take action to slow this trend.
    Toward this end, we cannot ignore the reality that coal is going to 
play a role in our nation's energy supply and the world energy supply 
for years to come. Coal generates half of the electricity in this 
country and is a reliable domestic source of power with a 250-year 
supply of coal in the U.S. alone.
    To fully maximize our use of coal, we must continue to take steps 
that reduce emissions. The only way to achieve this goal is through 
advancements in technology. I have been a strong supporter of clean 
coal initiatives and programs to advance the research and development 
needed to improve coal-based electricity generation. Congress must 
continue to support the clean coal programs in the President's FY08 
budget, which includes the FutureGen Project, slated to be the world's 
first zero-emissions coal plant. Among other things, FutureGen will 
demonstrate the ability to sequester carbon dioxide emissions safely 
underground. The more coal plants using clean coal technology equals 
less harmful emissions in our atmosphere and a reduction of greenhouse 
gases.
    Clean coal technologies do exist; however, they need the support 
and backing from Congress to further develop and demonstrate their 
commercial viability. As we consider climate change legislation, I 
encourage my colleagues to include coal as part of our energy solution. 
Again, I look forward to working with my colleagues as we find 
practical solutions that lead us down the path of energy independence 
and protection of our environment.
    I welcome the panel of witnesses and look forward to their 
testimony.

    [The prepared statement by Ms. Johnson follows:]
       Prepared Statement of Representative Eddie Bernice Johnson
    Thank you, Mr. Chairman. Today's hearing brings representatives of 
an important body of scientific knowledge on the state of science 
regarding climate change.
    The Intergovernmental Panel on Climate Change (IPCC) has spent 
hundreds, maybe thousands of hours preparing this report. The Panel 
gathered the world's leading experts on Earth science and surveyed the 
literature.
    The Panel took comments from the greater scientific community. All 
of this work has resulted in a high quality product that policy-makers 
should take seriously.
    I have been frustrated by the lack of action--real action--in 
dealing with climate change from the legislative standpoint.
    Why don't we mandate stricter standards to that all automobiles run 
on a greater number of miles per gallon of gasoline? Why haven't we 
passed into law good ideas such as the Chairman's on alternative fuel 
research and development?
    Why haven't we explored and utilized more of our domestic oil 
resources in the short-term, while investing heavily in solar, wind, 
nuclear, hydrogen fuel research and development?
    Why haven't we provided more incentives for the American people to 
buy fuel-efficient or hybrid vehicles?
    The number of unanswered questions of this nature keeps growing.
    I am eager to hear what today's witnesses have to say, and I thank 
the Chairman for inviting them to testify today.

    [The prepared statement by Mr. Lipinski follows:]
          Prepared Statement of Representative Daniel Lipinski
    I am pleased that with this hearing today, we will continue the 
discussion on the issue of global climate change in the House Committee 
on Science and Technology.
    The science on climate change has come a long way since the first 
international scientific conference on climate almost 30 years ago. 
This fourth assessment report by the IPCC represents a significant 
expansion in our knowledge of the influence of human activity on the 
Earth's climate. The solid scientific conclusions reached in this 
report allow us to move beyond debating whether humans are affecting 
climate change, and let us begin the discussion of how to resolve the 
dilemma before us.
    The challenges we face, which are documented in dramatic scientific 
detail within this report, highlight the need to act and act now. The 
need to find cleaner, less polluting sources of energy to reduce our 
impacts on climate change offers us a future of great opportunities, 
especially as we seek to compete in the global economy of the 21st 
Century.
    Fortunately, feasible approaches to reducing carbon dioxide 
emissions are no longer out of reach. In the 109th Congress, the House 
Committee on Science heard from U.S. businesses that had implemented 
energy efficient practices and manufacturing changes to reduce 
greenhouse gas emissions. I applauded the voluntary actions of these 
businesses for taking the lead even in the absence of mandatory 
requirements.
    This is a global challenge, and we must do our part to see that the 
health of our planet does not deteriorate further. As such, we must 
work on providing greater incentives to all U.S. businesses so they 
will continue to develop new environmentally friendly technologies and 
implement further reductions in greenhouse gas emissions.
    I look forward to the release of the Working Group II and Working 
Group III reports later this spring and welcome the chance to learn how 
we might go about mitigating global climate change. It is my hope that 
creative and vigorous dialogue in the 110th Congress will yield 
concrete results that will put us on the right path toward a more 
sustainable future.

    [The prepared statement by Mr. Ross follows:]
             Prepared Statement of Representative Mike Ross
    I would like to first thank Chairman Gordon and Ranking Member Hall 
for holding today's hearing on climate change. I would also like to 
thank Speaker Pelosi for coming before the Committee today and all of 
the witnesses who have come here to discuss their findings on this 
topic.
    I am honored that our committee will be the first to hear from the 
authors of the Intergovernmental Panel on Climate Change's Report on 
Global Climate Change.
    I strongly believe that our nation must develop a comprehensive 
plan that combats climate change by investing in alternative and 
renewable fuels and reducing greenhouse gas emissions and I am hopeful 
that today's hearing will continue the discussion of climate change to 
aid in this process. I also believe in a common sense approach to 
imposing regulations that will help to improve our environment and 
combat the harmful effects of global warming, while maintaining jobs 
and strengthening our nation's economy.
    I am hopeful that all of these goals can be met and I look forward 
to today's discussion of the IPCC's report, which will provide great 
insight into this topic.

    [The prepared statement by Mr. Carnahan follows:]
           Prepared Statement of Representative Russ Carnahan
    Mr. Chairman, thank you for placing this important hearing first on 
the calendar of the Committee on Science and Technology for the 110th 
Congress. By prioritizing it on our agenda, you have helped to 
emphasize the growing importance of climate change on the national 
debate.
    Speaker Pelosi, it is a tremendous honor to have you appear before 
us today and I look forward to hearing your testimony on the state of 
climate change. Your presence speaks loudly to your commitment to 
bipartisan action on this very important issue. Thank you for joining 
us.
    The conclusions of the Intergovernmental Panel on Climate Change 
(IPCC) have clarified that human-induced influences impact the climate. 
With very high confidence, the IPCC now tells us that the Earth is 
warming as is indicated by an increase in global average air and ocean 
temperature, widespread melting of snow and ice, and rising global 
average sea level. While this news is unfortunate, the certainty with 
which science now warns that human actions are impacting the climate 
should motivate the Congress to move forward on legislative solutions.
    I am proud to say that last Congress I was very active on the issue 
of global warming, introducing a bipartisan and bicameral Sense of 
Congress resolution, H.Con.Res. 453, aimed at addressing global warming 
through the negotiation of international treaties. Furthermore, during 
debate on the 2005 Energy bill, I attempted to amend the bill by 
redrafting and extending the Hybrid tax credit, a credit that was 
eventually enacted into law and is a step forward in our efforts to 
stem harmful emissions.
    St. Louis has one of the highest rates of asthma and respiratory 
diseases in the country, the causes of which are directly related to 
global warming. For this reason, climate change is an issue of vital 
importance to my constituents.
    I look forward to hearing the testimony of Speaker Pelosi and the 
IPCC witnesses and participating in the conversation of climate change 
as we deliberate over legislative solutions in the 110th Congress. 
Thank you all for being here today.

    [The prepared statement by Mr. Mitchell follows:]
         Prepared Statement of Representative Harry E. Mitchell
    Thank you, Mr. Chairman.
    I think one of the things the American people are hoping from this 
Congress is for Democrats and Republicans to work together to take the 
threat of global warming to our environment and our national security 
seriously.
    We are watching our planet rapidly change before our eyes. Once 
majestic ice caps are melting. Weather patterns are changing in very 
troubling ways. The temperature of our atmosphere is on the rise. The 
intensity of rains and drought are more extreme. Hurricanes, such as 
Katrina, are becoming more powerful, and more deadly.
    The scientific evidence that global warming exists--and that humans 
are largely responsible for the change in our climate--is overwhelming.
    The report by the Intergovernmental Panel on Climate Change--which 
we are hearing more about today--continues to confirm our fears about 
global warming.
    I hope that as the American people and the international community 
continue to learn about this report and the effects of global warming, 
our renewed interest in the topic will turn into action.
    The United States is the world leader in the emission of greenhouse 
gases. That means we have a moral obligation to lead the world to a 
solution.
    I believe that America's ingenuity, and our unique spirit can be an 
incredible asset in this cause. Our action on global warming can also 
help restore our authority as a respected global leader.
    Developing sound policy on global warming--and investing in new 
technologies and clean energy--can help grow our economy too.
    This Congress, the President and the American people have a 
responsibility, and I hope that we re-dedicate ourselves to meeting 
that responsibility.

    [The prepared statement by Mr. Ehlers follows:]
         Prepared Statement of Representative Vernon J. Ehlers
    I am pleased that the Science and Technology Committee is hearing 
from scientists who participated in the Intergovernmental Panel on 
Climate Change, especially so soon after the Summary for Policy-makers 
was released. We're fortunate to receive this information ``hot off the 
presses'' (if I am allowed to think that anything ``hot'' is a good 
thing given today's topic).
    In my mind, there are three big questions related to climate 
change. One, is climate change happening? Two, to what extent is it 
anthropogenic? And three, what are we going to do about it? I believe 
that the research the panelists will discuss today advances our 
knowledge of the answers on the first and second of these questions. We 
need to hear how the methods of monitoring changes in the Earth have 
improved, and what the most recent data indicates, especially since the 
last major assessment was finalized in 2001. But an even bigger task 
for this committee and our colleagues is to answer the third question: 
what are we going to do about climate change? Comprehensive and 
continuing science is critical for us to be able to answer that 
question. The additional working groups of the IPCC also will help 
address the broader policy questions of climate change strategy, and I 
look forward to reviewing those results in the spring.
    Our planet is a dynamic system, and any attempts to mitigate 
warming, adapt to sea level rise, or any other response to climate 
change will rely on scientific research and researchers, like those 
testifying before us today. These individuals have dedicated not just 
hours, but years to the process that results in the full assessment of 
climate science due in May. I thank them for that commitment, and look 
forward to the opportunity to hearing what they have to say.

    [The prepared statement by Mr. Neugebauer follows:]
         Prepared Statement of Representative Randy Neugebauer
Mr. Chairman:

    Thank you for holding this hearing. I welcome the opportunity to 
take part in this important discussion and look forward to hearing from 
our distinguished panelists.
    Like everyone else, and despite the recent record cold temperatures 
here in DC and around the country, I believe the Earth has gotten 
warmer over the past century. I don't doubt that there is consensus on 
that fact. Beyond that, however, I see a lot of disagreement.
    On the one hand, we have the distinguished scientists before us who 
have authored key findings of the IPCC's report. They--and others--
believe ``with more than 90 percent confidence'' that, based on their 
models and data, human activity is chiefly responsible for global 
warming since the 1950s.
    On the other hand, we have other distinguished scientists who 
disagree with that assessment. Some believe that humans, to varying 
degrees, have played a role in global warming. Others believe that 
solar activity has been the primary factor, given their models and 
data.
    The bottom line, Mr. Chairman, is that the scientific community 
does not speak with one voice on this important issue. And that's not 
unusual. It happens all the time with scientific inquiry. New models 
are developed; data is re-examined; new hypotheses are tested. That's 
normal and healthy--when you have a robust scientific community free of 
political or ideological interference.
    But Mr. Chairman, what I've seen lately has been disturbing--and it 
should concern every American. Scientists who disagree with the popular 
view on global warming are being ostracized. They are being labeled 
``global warming deniers.'' We have politicians and activists--most of 
whom are not scientists themselves--working to silence highly trained 
and accredited scientists. Some call for silencing their disagreement 
by revoking professional certifications and removing them from key 
positions.
    Mr. Chairman, why has the reaction to these differing scientific 
findings been so extreme and so reckless? I strongly suspect that 
ideology, not scientific disagreement, is behind this reaction.
    Mr. Chairman, it is an inconvenient truth that we run a terrible 
danger when scientific debate is stifled because it gets in the way of 
political goals.
    We in Congress, and in this committee especially, are called upon 
to make scientific and environmental policy that will affect our 
economy, our security, and our general welfare; and not just for us, 
but for future generations of Americans, as well.
    To the best of my knowledge, none of us sitting on this committee 
are climatologists or meteorologists or otherwise competent on our own 
merits to claim full knowledge of this complex issue. So, we deserve to 
have all the scientific information before us--to consider it, and to 
make the wisest policy choices based on all the findings before us.
    Mr. Chairman, you have indicated that it's time to end the debate 
on this issue. But I respectfully disagree with that assessment. It is 
plain that the debate has just begun.
    I hope future hearings on global warming will provide the 
opportunity to hear opposing views and have a full healthy debate and 
dialogue on this issue.
    Thank you.

    Chairman Gordon. I ask unanimous consent that 
Representative Gilchrest, who was a former Member of this 
committee, be permitted, at his request, to sit at the dais for 
this hearing and that he be permitted to ask questions after 
all Members of the Committee have an opportunity to question 
the witnesses. Mr. Sensenbrenner, is that okay with you?
    Mr. Sensenbrenner. I just want to see the rules followed.
    Chairman Gordon. All right. Thank you. Without objection, 
so ordered.
    Now it is my pleasure and privilege to welcome the Speaker 
of the House of Representatives, Nancy Pelosi, to be with us 
today. I know this is an issue that you are both informed about 
and have a passion about. And we welcome you here for this 
hearing and welcome to hear your remarks.

                                Panel I:

 STATEMENT OF THE HONORABLE NANCY PELOSI, SPEAKER OF THE HOUSE 
                       OF REPRESENTATIVES

    Speaker Pelosi. Thank you very much, Mr. Chairman.
    I thank you and your distinguished Ranking Member, Mr. 
Hall, for the courtesy extended here today for me to present my 
views before this very important committee.
    The last time I was in this room was for the unveiling of 
the portrait of Mr. Boehlert, and here we are, portrait and Mr. 
Boehlert, as well, and I join you in thanking him for his great 
leadership to our country and in working in a bipartisan way to 
use science as a basis for progress in our country.
    I want to also join in commending the witnesses who will be 
presenting today. I thank them for their extraordinary 
contribution to understanding of climate change. Their new 
report confirms that climate change is indisputably underway 
and states with 90 percent certainty that greenhouse gases 
released by human activities are the main cause of global 
warming.
    I am very pleased to see on the wall, which in the 
excitement of Mr. Boehlert's unveiling, I didn't see that day 
several months ago, that you quote Tennyson, who is my favorite 
poet, Alfred Lord Tennyson. And it says, ``For I dipped into 
the future, as far as human eyes could see, saw the vision of 
the world and all the wonder that would be.'' What a wonderful 
inspiration to the work of this committee.
    You, on this committee, are opening a window into our 
future. Looking through that window, we see a future in which 
global warming will reshape our planet and our society. We also 
see a future in which harsh consequences could be blunted by 
prompt action. That is the good news.
    This is an issue that is as immediate to the American 
people as their own neighborhoods and as global as the planet 
itself. It was interesting to me that on a recent visit from 
the Executive Committee of the U.S. Conference of Mayors, a 
bipartisan Committee, they brought forth their 10-point program 
for strong cities, strong families, a strong America. And point 
number one in the Conference of Mayors' 10-point proposal was 
energy independence, climate change, global warming. That was 
their top priority. They had best practices, that they, in a 
bipartisan way, are sharing with each other and instituting in 
their communities. Again, this is as immediate to the lives of 
the American people as their own neighborhoods, and again, it 
is as global as the planet. And that--more on that in just a 
moment.
    On the science of global warming, the level of carbon 
dioxide in the atmosphere is by far the highest in 650,000 
years. Temperatures are estimated to rise anywhere from two 
degrees Fahrenheit to as high as 11.5 degrees by the end of the 
century. We can expect rising sea levels, more intense storms, 
increased drought in some areas and more floods in others, heat 
waves, spread of tropical diseases, extinction of species, 
changes in ocean salinity, and melting ice in the polar 
regions, and that is already happening.
    The catastrophic hurricanes of 2005, Katrina and Rita, 
foreshadow the challenges we will face. All along our 
coastlines, our great cities and small towns will be threatened 
by rising sea levels and intensifying storms.
    Not only coastal areas will be affected. Inland communities 
will be gravely affected as well by drought and flood. Movement 
of climate change refugees from one country to another could 
increase political instability in many regions of the world. 
These environmental refugees are a real, real concern.
    Looking through the window into the future that you have 
opened, we also see that we can reshape our activities now and 
prevent catastrophic global warming. Where once we thought the 
effects of global warming would occur decades away, change is 
already underway.
    We hold our children's future in our hands, not our 
grandchildren, or great-grandchildren, but our own children. As 
the most adaptable creatures on the planet, it is time for us 
to continue to adapt.
    Scientific evidence suggests that to prevent the most 
severe effects of global warming, we will need to cut global 
greenhouse gas emissions roughly in half from today's levels by 
2050. The Bush Administration continues to oppose mandatory 
limits on greenhouse gases, restating this position immediately 
upon the release of the IPCC report. I respectfully disagree 
with the distinguished Ranking Member in his comments, and this 
is a wonderful venue for the debate, this very important 
committee with these very informed Members.
    I do believe, though, Mr. Hall and Mr. Chairman, we cannot 
achieve the transformation we need, both in the United States 
and throughout the international community, without mandatory 
action to reduce greenhouse gas pollution. Many of the 
technologies to revolutionize our use of energy are already at 
hand, as the distinguished gentleman mentioned, and we can 
develop others, waiting on the shelf, or under development. 
Restrictions on greenhouse gas emissions will drive these 
technologies into the marketplace quickly and cost-effectively, 
while simultaneously creating the next generation of good-
paying new jobs.
    In addition, we must address land-use policies in the U.S. 
and worldwide, since the loss of forests currently contributes 
about 25 percent of global carbon dioxide emissions. Older 
forests can store more carbon while also providing fuel for 
biomass energy in a sustainable manner.
    We have a responsibility to work together with countries, 
as the distinguished Ranking Member Mr. Hall said, but these 
other countries, India and China, to name two, to work with 
them for them to reduce the level of carbon dioxide in the 
atmosphere. That may be as important to our grandchildren and 
our children's future as anything we do here. The United States 
and China, as well as India, are the largest contributors of 
carbon dioxide emissions in the world, and it is estimated that 
China will surpass the United States in three years.
    We need to engage the Chinese government by working 
cooperatively to develop clean and renewable sources of energy.
    I have asked the Chairs of the committees of jurisdiction 
to work with their Ranking Members in a bipartisan way with the 
Members of the Committees to develop legislation over energy, 
environment, and technology policy and to report that 
legislation to us no later than June 1 so that we can have an 
energy independence global warming package by the 4th of July.
    This committee is way ahead of the rest. It has 
legislation, as has been mentioned, on the Floor today, and I 
commend you for that, Chairman Gordon and Mr. Hall and Members 
of the Committee. I know that you have other legislation that 
relates to innovation and the innovation agenda, which is 
directly related to this issue that will help advance the 
technologies needed to help save our planet.
    We hope to have legislation that will be a starting point 
on global warming and energy independence soon. Again, you have 
taken the lead.
    I also want to mention that we are creating a Select 
Committee on Energy Independence and Global Warming to raise 
the visibility of these urgent issues and gather critical 
information to protect America's security. This is a national 
security issue. The Select Committee will not have legislative 
jurisdiction, but will develop policy strategies, technologies 
and other innovations intended to reduce the dependence of the 
United States on foreign sources of energy, and to achieve 
substantial and permanent reductions in emissions and other 
activities that contribute to climate change and global 
warming. The Select Committee will share its findings with the 
legislative committees of the House and with the public, and 
they will make a special effort to communicate with younger 
Americans by using the most cutting-edge technologies. Young 
people are very concerned about the issue of global warming. It 
is natural, because the future is theirs, and this has a big 
impact on the future.
    For 12 years, the leadership in the House of 
Representatives has stifled all discussion and debate on global 
warming. The long rejection of reality is over, to the relief 
of Members, I believe, on both sides of the aisle.
    We teach our children, Mr. Chairman and Ranking and other 
Members of the Committee, that everything in nature is 
connected, and indeed, it is. The Bible tells us in the Old 
Testament that, ``To minister to the needs of God's creation is 
an act of worship. To ignore those needs is to dishonor the God 
who made us.'' Indeed, this planet is God's creation. That is 
why large segments of the evangelical movement have become part 
of this effort to curb and stop global warming. We have a 
responsibility to make an act of worship by protecting God's 
creation.
    There is a growing chorus of voices, including 
evangelicals, in favor of taking serious and sustained action 
on global warming, from scientists to Fortune 100 CEOs, from 
evangelical Christians to environmentalists, from farmers to 
hunters and anglers. We will work together, holding hearings, 
developing legislation, and tackling one of America's--
humanity's--greatest challenges yet: global warming.
    With that, Mr. Chairman, I thank you, once again, for the 
opportunity to present my views as Speaker of the House to you 
and to Mr. Hall with the promise that this is not about taking 
one point of view and going forward but in trying to work in a 
bipartisan way for sustainable initiatives that we can agree 
upon and make a difference for our children and see ``the 
vision of the world and all the wonder that would be'' in this 
important committee. Thank you, Mr. Chairman.
    [The prepared statement of Ms. Pelosi follows:]
               Prepared Statement of Speaker Nancy Pelosi
    Thank you, Chairman Gordon, for holding this important hearing on 
the findings of the Fourth Assessment Report by the Intergovernmental 
Panel on Climate Change (IPCC). Thank you, Ranking Member Hall, and my 
colleagues on the Science and Technology Committee for your attention 
to the pressing issue of climate change.
    To the witnesses appearing today, thank you for your extraordinary 
contributions to our understanding of climate science. Your new report 
confirms that climate change is indisputably underway and states with 
90 percent certainty that greenhouse gases released by human activities 
are the main cause of global warming.
    You have opened a window into our future. Looking through that 
window, we see a future in which global warming will reshape our planet 
and society. We also see a future in which harsh consequences could be 
blunted by our prompt action.
    The level of carbon dioxide in the atmosphere is by far the highest 
in 650,000 years. Temperatures are estimated to rise anywhere from two 
degrees Fahrenheit to as high as 11.5 degrees by the end of the 
century. We can expect rising sea levels, more intense storms, 
increased drought in some areas and more floods in others, heat waves, 
spread of tropical diseases, extinction of regions.
    The catastrophic hurricanes of 2005, Katrina and Rita, foreshadow 
the challenges we will face. All along our coastlines, our great cities 
and small towns will be threatened by rising sea levels and 
intensifying storms.
    Not only coastal areas will be affected. Inland communities will be 
gravely affected as well by drought and flood. Movement of climate 
change refugees from one country to another could increase political 
instability in many regions of the world.
    Looking through the window into the future that you have opened, we 
also see that we can reshape our activities now and prevent 
catastrophic global warming. Where once we thought the effects of 
global warming would occur decades underway.
    We hold our children's future in our hands--not our grandchildren, 
or great-grandchildren, but our own children. As the most adaptable 
creatures on time for us to adapt.
    Scientific evidence suggests that to prevent the most severe 
effects of global warming, we will need to cut global greenhouse gas 
emissions roughly in half from today's levels species, changes in ocean 
salinity, and melting ice in the polar away, change is already the 
planet, it is by 2050. The Bush Administration continues to oppose 
mandatory limits on greenhouse gases, restating this position 
immediately upon the release of the IPCC report.
    We cannot achieve the transformation we need, both in the United 
States and throughout the international community, without mandatory 
action to reduce greenhouse gas pollution. Many of the technologies to 
revolutionize our use of energy are already at hand, waiting on the 
shelf, or under development. Restrictions on greenhouse gas emissions 
will drive these technologies into the marketplace quickly and cost-
effectively, while simultaneously creating the next generation of good-
paying new jobs.
    In addition, we must address land-use policies in the U.S. and 
worldwide, since the loss of forests currently contributes about 25 
percent of global carbon dioxide emissions. Older forests can store 
more carbon while also providing fuel for biomass energy in a 
sustainable manner.
    We have a responsibility to work together with countries such as 
China to reduce the level of carbon dioxide in the atmosphere. The 
United States and China are the two largest contributors of carbon 
dioxide emissions in the world and it is estimated that China will 
surpass the U.S. in just three years.
    We need to engage the Chinese Government by working cooperatively 
to develop clean and renewable sources of energy.
    I have also asked the committees that have jurisdiction over 
energy, environment and technology policy to report legislation on 
these issues by June. We hope to have legislation that will be a 
starting point on global warming and energy independence through the 
committees by July 4th, so that this year, Independence Day is also 
Energy Independence Day.
    We are creating a Select Committee on Energy Independence and 
Global Warming to raise the visibility of these urgent issues and 
gather critical information to protect America's security. The Select 
Committee will not have legislative jurisdiction, but they will develop 
recommendations on policies, strategies, technologies and other 
innovations intended to reduce the dependence of the United States on 
foreign sources of energy, and to achieve substantial and permanent 
reductions in emissions and other activities that contribute to climate 
change and global warming. The Select Committee will share its findings 
with the legislative committees of the House and with the public, and 
they will make a special effort to communicate with younger Americans 
by using the most cutting-edge technology.
    For twelve years, the leadership in the House of Representatives 
stifled all discussion and debate of global warming. That long 
rejection of reality is over, to the relief of Members on both sides of 
the aisle.
    The Bible tells us in the Old Testament, `To minister to the needs 
of God's creation is an act of worship. To ignore those needs is to 
dishonor the God who made us.'
    There is a growing chorus of voices in favor of taking serious and 
sustained action on global warming: from scientists to Fortune 100 
CEOs, from evangelical Christians to environmentalists, from farmers to 
hunters and anglers. We will work together, holding hearings, 
developing legislation, and tackling one of humanity's greatest 
challenges yet global warming.

                               Discussion

    Chairman Gordon. Speaker, thank you for joining us today. 
You are the first Speaker to be before this committee. I have 
only been here 22 years, but you are the first Speaker that I 
know of in those 22 years to make a presentation before any 
committee, and I suspect this may be groundbreaking in the 
history of the Congress, which I think demonstrates your 
passion and leadership on this issue, and we appreciate you 
being here.
    My Ranking Member Hall and I have no questions. We are 
going to let Mr. Sensenbrenner have his question, and then I am 
going to ask that we have unanimous consent that any further 
questions be submitted by writing.
    Mr. Sensenbrenner.
    Well, then Mr. Sensenbrenner will have the first question.

                   Economic Impacts of Climate Change

    Mr. Sensenbrenner. Thank you very much, Madame Speaker.
    Speaker Pelosi. Thank you, Mr. Sensenbrenner.
    Mr. Sensenbrenner. I welcome you here today.
    Speaker Pelosi. Thank you.
    Mr. Sensenbrenner. I hope that you and your successors 
engage in the debate on the issues before the Congress, and I 
think that this is a very welcome development.
    I really do have to take issue with your comment in your 
statement that for 12 years there was no discussion of global 
warming, because during my chairmanship of this committee, and 
particularly in 1998 and 1999, we had a number of hearings at 
the Full and Subcommittee level relative to the Kyoto protocol, 
the science behind it, and the economic consequences this 
ratification would entail to the United States and its workers. 
One of those witnesses was the head of the Energy Information 
Agency in the Department of Energy who was a direct appointee 
of President Clinton. And this man testified that the 
ratification of Kyoto and the caps that are similar to that 
which you are advocating, would cause a 60 to 80 percent 
increase in the cost of natural gas, electricity, and fuel oil 
to the American consumer. And given the fact that China is not 
under any caps and as late as last week said that they didn't 
want to do that, I would ask you to look at the impact on 
American jobs, because we do not want to have anything we do 
result in the outsourcing of American jobs to countries like 
China and India and Mexico that have not capped or even slowed 
down their growth in greenhouse gas emissions. What are you 
planning to do, Madame Speaker, to make sure that we don't 
legislate on this area in a way that wrecks the American 
economy and costs our workers jobs?
    Speaker Pelosi. Thank you, Mr. Sensenbrenner.
    Whatever actions we take have to be based, I believe, on 
science and on the facts. And one fact is that America must 
innovate in this arena for us to be ahead. We look forward to 
doing this in a bipartisan way. We know that there will be 
impacts on the coal industry, on other sources of energy, and 
we want to hear what those industries have to say. So this 
isn't about running roughshod. This is about working together. 
And hopefully we can work in a bipartisan way with the 
President of the United States in order to do this. I see it as 
an economic opportunity, a place where green can be gold for 
our country where the technologies we develop for dealing with 
the coal industry and other industries in our country on which 
we are dependent now for energy using their initiatives, 
because they are making change, and we have to listen to them 
as well, to Mr. Rahall and Mr. Boucher, who represent these 
districts, Members of the Republican party who represent them 
as well.
    So what we want to do is do something where we have as much 
unity as possible, and we certainly are sensitive to the issue 
of economic growth in our country.
    Mr. Sensenbrenner. Well, Madame Speaker, just to follow up, 
I would make the observation that there are two sides to the 
equation. One is the scientific side and relative to emissions 
of greenhouse gases. The other is the economic consequences of 
any actions that we take. And you know, I am very fearful the 
way this debate has been joined and, given who the witnesses 
are following you, that we are looking at one side of the 
equation and ignoring the other side, and we can't do that for 
the sake of American jobs.
    And I yield back the balance of my time.
    Speaker Pelosi. Yes, I agree with that, Mr. Sensenbrenner. 
We can't ignore it, but we also can't ignore the consequences 
of not doing something, because that will have an economic 
impact as well.

       Select Committee on Energy Independence and Global Warming

    Chairman Gordon. Thank you. Mr. Sensenbrenner, I will point 
out that the Minority had the right to submit witnesses. I 
think that you had one. You withdrew him. And so this was not a 
rigged jury, but rather it may be by default. Maybe no one else 
wanted to come up and speak. But that is where we are.
    Madame Speaker, as we gather together here, I know you had 
mentioned earlier, again, your passion for this and that you 
wanted to develop a Select Committee. Could you tell us more 
about that Select Committee and why it is so important and what 
you want to do with it?
    Speaker Pelosi. Thank you, Mr. Chairman.
    There are eight or nine committees of jurisdiction on this 
issue ranging from this important committee, the Ways and Means 
Committee, the International Relations Committee, as has been 
pointed out by Mr. Sensenbrenner, and the distinguished Ranking 
Member, other countries have a big impact on how we go forward 
on this issue. And so this Select Committee was designed to try 
to get some of the best information possible by communicating 
directly in the cities of America where, again, best practices 
are being used to address this issue, where the bipartisan 
Conference of Mayors is putting forth global warming and energy 
independence as their top priority in their 10-point program, 
working with the governors, working with leaders around the 
world. The European Union is way ahead of us on this issue. 
They see it as an economic issue, Mr. Sensenbrenner. They see 
it as an economic issue. They know that they want to be out 
there in front with the technologies that will enable us to 
curb global warming, and that is in our economic interest. The 
United Nations, of course we have this report, but the United 
Nations has this as a priority as well.
    I have asked this--a Select Committee to--whether it is as 
local as a neighborhood, as global as the planet, to help 
communicate this message, get the best possible information. I 
could have done it as a task force within the Democratic party, 
but I wanted it to be bipartisan so we had every point of view 
represented, different views in our own party as well as views 
within the Republican party so that as we go forward, we are 
doing so in a way that is understanding the consequences of it.
    So it is a way for us to communicate with the next 
generation of leaders in our country, to communicate with 
countries that have a big impact on global warming like China 
and India, communicate to the neighborhoods of America that 
everyone is involved in this decision, because everyone is 
affected by it. And we want to go forward in a temperate way 
but in a bold way to make a difference for our children.
    So that is the purpose of it. It does not have legislative 
authority. It will end at the end of this Congress, and I think 
it will be a force for good.
    Chairman Gordon. Mr. Hall.
    Mr. Hall. Mr. Chairman, I have no questions for this 
speaker. And we did invite, from the United States Chamber of 
Commerce one of the great bodies of advice for this committee. 
They said they did not have the time to answer the political 
questions. They thought it was going to be on science alone. It 
is not that. And we will have them before you later.
    I yield back any time that you might yield to me.
    Chairman Gordon. Well, Mr. Hall, I think you will find that 
the IPCC Report is the scientific definitive statement on this 
issue and we look forward to hearing that.
    Let us see. Is there anyone else on the top row?
    Mr. Akin.

                             Nuclear Energy

    Mr. Akin. Thank you, Mr. Chairman.
    And I appreciate your allowing us to ask a few questions. 
And it is a very interesting debate. Madame Speaker, thank you 
for joining us this morning.
    Speaker Pelosi. Thank you.
    Mr. Akin. Your comments, you laid out a couple of basic 
premises that you were assuming. The first premise is that the 
Earth is getting warmer. I don't think there is a lot of debate 
on that. I think the Earth is getting warmer.
    The second one is maybe another question that is 
interesting. It is being caused by our burning hydrocarbons. 
If, in fact, you apparently believe that to be true, my 
question is, do you endorse the expansion of nuclear energy, 
because that does not burn hydrocarbons?
    Speaker Pelosi. Mr. Akin, in the early days of my life in 
the Congress, I was an opponent of nuclear energy, because I 
didn't know what was going to be done--how we would dispose of 
the waste from it.
    Your question is a good one, because the technology has 
changed, and I bring a more open mind to that subject now, 
because I think we have to look at the technology and really 
compare it to what the alternatives. If they are looking at 
India and we are looking at China and looking at them putting 
on more coal-burning plants than we have in the United States, 
that they are just going to even add now, and the alterative 
might be nuclear, we have to weigh what that does to the 
environment. But I think that the answer is always with 
technology. If we can't--if the technology is at a place where 
we can dispose of the waste, well, let us at least try to move 
it to that place. But I have a different view of nuclear energy 
than I did, say, 20 years ago when I came to this----
    Mr. Akin. I think what I hear you saying is that you 
would--assuming that a reasonable proposal could be made, that 
nuclear could be the substitute for burning hydrocarbons.
    Speaker Pelosi. Well, I would say I would not, as I did in 
my youth, be an active opponent of such a thing, but hope that 
we would work together to take it to a place where we can 
dispose of the waste. That is the big challenge. But I will say 
this. Again, we have to always compare it to if not this, then 
what, and what does that do in terms of global warming. So I 
think it has to be on the table.
    Mr. Akin. That is interesting. I appreciate your open-
mindedness to that alternative.
    Speaker Pelosi. I do have an open mind.

         The International Banking Environmental Protection Act

    Mr. Akin. That is something from an engineering 
perspective--I am one of the few engineers, I guess, that 
managed to get into Congress. Perhaps by mistake, but that is 
something that has always seemed very logical, even though 
there was sort of a political prejudice against it. The global 
or geophysical research letters estimated in 1997 that if the 
Earth, that is all of the nations, lived up to the United 
Nation's Kyoto protocol on global warming, that we would 
prevent no more than 0.1 to 6 degrees Fahrenheit of warming in 
50 years. That says that you are talking about some pretty 
strong actions that are going to have to be taken. I think this 
makes fixing Social Security look easy by comparison. And I 
guess I am wondering, you talk about the fact that we have got 
the highest level of CO2 in 650,000 years. I guess 
my question is, how was it that Greenland was harvesting corn 
in the year, what, 900 or 1000 if the CO2 was so 
high? Or was there something else making the world warm? And is 
it so bad if it gets warmer?
    Speaker Pelosi. Well, that is a very good question. About 
19 or 18 years ago, early in my term in Congress, I had a piece 
of legislation that was called the International Banking 
Environmental Protection Act, and it goes right to your final 
question. That was a bill that said--that talked about the 
International Bank, the World Bank, the Interamerican Bank, the 
Asian--all of the multi-development banks. It was a piece of 
legislation that I introduced on the Banking Committee. And at 
the time, I had opposition from my fellow Democrats on the 
legislation because it called for an environmental impact 
statement to be made on any projects that the United States 
would vote on and that the results of that impact statement 
would be made known to the indigenous people of the region as 
well as internationally. So that is the bottom line of it.
    At the very same time--now this had to be--President Bush 
was President, so it was after President Reagan, so it was, 
say, 1990, something like that. At that time, the President of 
the World Bank said, a very distinguished gentleman, but this 
is what he said. He said, ``What difference does it make if 
there is global warming, if there is climate change? We can 
just go develop those countries where the snow--those areas 
where the snow is melting.'' It wasn't really a very informed 
statement, and that was, again, like 1990, and it did more to 
pass my bill than anything I could do, even getting past the 
Democrats on the Committee who were not particularly well 
inclined, and President Bush signed it into law.
    Mr. Akin. I guess----
    Speaker Pelosi. But there was a reality at the time, and 
there are serious consequences to global warming, and we have 
to face that reality.
    Chairman Gordon. The gentleman's time is up. I would----
    Mr. Akin. Thank you, Mr. Chairman.
    Chairman Gordon.--suggest that it may not matter to 
Missouri about global warming, but if Greenland loses all of 
its ice and snow, then our friends around the coast are going 
to be concerned about it, because there will be an enormous 
amount of flooding. I recognize----
    Mr. Hall. Mr. Chairman, would you yield?
    Chairman Gordon. Yes, Mr. Hall.
    Mr. Hall. I think what you are really saying is if we 
really want to alter the warming trend significantly, we are 
going to have to cut emissions by a very large amount, even 
beyond Kyoto. And the question is, that I think the gentleman 
is asking down there, is do we currently have affordable 
technologies for significantly reducing greenhouse gas 
emissions, and is there any estimate of cost, and who pays? I 
think that is the major question. That is the reason the 
gentleman from----
    Speaker Pelosi. That is a good answer.
    Chairman Gordon. That is a good----
    Mr. Hall. The U.S. Chamber did not want to come on such 
short notice.
    Chairman Gordon. Well, I have a high regard for the Chamber 
and their intelligence and their ability, and I think that they 
could have made a good statement, but you have raised a good 
question. The good news is we have a panel of scientists that 
just got through working on a report with 113 nations, I think 
6,000 scientists, approved by this country and this President, 
and we are going to hear from them with those very specific 
answers, and I am glad we are going to be able to do that.
    Mr. Costello.

           Question and Answer Session: Congressional Customs

    Mr. Costello. Mr. Chairman, thank you.
    Mr. Chairman, I do not have any questions for the 
distinguished Speaker, but let me say that I am very 
disappointed and very surprised that we have not extended to 
this witness, to the Speaker of the House, the same courtesy 
that we have extended to many Members of the House of 
Representatives since I have served on this committee.
    I have served on the Science Committee for 18 years. As I 
recall under the leadership, I think the record will reflect, 
under the distinguished Chairman Sherry Boehlert, under Mr. 
Sensenbrenner, under every Chairman of this committee since I 
have been there serving on this committee, I can recall many 
Members of Congress testifying, presenting their statement 
before this committee, and we extended the courtesy to them 
because of demanding schedules, let alone the Speaker of the 
House of Representatives, allowed them to submit their 
testimony and to leave without going through the long ordeal of 
questions.
    I serve on the Transportation and Infrastructure Committee, 
as Mr. Boehlert did in his service in the Congress. We extended 
the same courtesy there to countless Members of Congress, and I 
just have to tell you that I am extremely surprised. This is 
the first, but it won't be the last time that we are going to 
debate this issue in this committee and a whole host of other 
committees. So I just have to tell you, I am very disappointed 
and very surprised.
    Mr. Rohrabacher. Would the gentleman yield?
    Mr. Costello. We are--I will in just one second. That we 
are subjecting the Speaker of the House of Representatives to a 
higher standard than we have extended the courtesy to other 
Members. Again, I----
    Mr. Rohrabacher. Would the gentleman yield?
    Mr. Costello. Yes, I will.
    Mr. Rohrabacher. I agree with you.
    Speaker Pelosi. Thank you, Dana.
    Chairman Gordon. Well, the good news is that we have a 
great Speaker who can handle herself very well.
    Speaker Pelosi. I do have to leave.
    Chairman Gordon.We have to reset our timer, and so as we do 
that, I am going to recess this committee.
    Speaker Pelosi. And may I just--may I thank you, Mr. 
Chairman?
    Chairman Gordon. Yes, you may.
    Speaker Pelosi. May I thank the distinguished Chairman and 
Ranking Member, Members of the Committee. It is the first 
committee that I have testified before as Speaker of the House. 
And because you are a committee about the future, I think that 
is perfectly appropriate. I wish you much success in your 
deliberations.
    Thank you, Mr. Chairman.
    Chairman Gordon. You made this a better hearing. Thank you.
    Speaker Pelosi. Thank you.
    Chairman Gordon. And we are in recess.
    [Recess.]
    Chairman Gordon. Thank you all. We have our clocks working 
again. And now that we have our equipment back in shape, we 
will recommence. And I will call this committee back to order, 
and I would like to call our panel of witnesses to the table. 
Thank you.
    We are very pleased to have this distinguished panel of 
climate scientists here for this morning. All of our four 
witnesses have just returned from Paris where they have 
participated in the preparation of the Summary for Policy-
makers release by the IPCC last Friday.
    I will begin by introducing Mr. Richard Alley. Mr. Alley is 
a Professor of geosciences and an associate of Earth and 
Environmental Systems Institute at the Pennsylvania State 
University. Mr. Alley is an expert in the area of glaciers and 
ice sheets and their potential to cause changes in the sea 
level. He serves on the National Academy of Sciences' Polar 
Research Board and chaired the NAS Panel on Abrupt Climate 
Change. Mr. Alley was a Lead Author of Chapter 4 of the IPCC 
Report dealing with changes in snow, ice, and frozen ground.
    I will now yield to Representative Udall, if Mr. Udall is 
here, yes, to introduce the remaining three panelists who are 
members and constituents from his district.
    Mr. Udall.
    Mr. Udall. Thank you, Mr. Chairman. And many of you on the 
Committee know that Boulder is home to many outstanding climate 
science facilities, including NOAA's Earth System Research 
Laboratory and the National Center for Atmospheric Research.
    And I want to start with Dr. Susan Solomon. She serves as 
the Co-Chair of Working Group I of the IPCC, and she provided 
overall coordination for the report. Dr. Solomon received her 
Ph.D. in chemistry from the University of California at 
Berkeley in 1981 and currently is a senior scientist at NOAA's 
Earth System Research Laboratory. A couple of interesting 
background facts about Dr. Solomon, she has a glacier named 
after her in the Antarctic because of her work on the causes of 
the ozone hole. She is a member of the National Academy of 
Sciences. And in March of 2000, she received the National Medal 
of Science, the United States' highest scientific honor, for 
her ``Key on Insights in Explaining the Cause of the Antarctic 
Ozone Hole.'' She has also written a book, which is of great 
interest to me as an aging mountaineer, called ``The Coldest 
March,'' which covers the tragic story of Captain Robert Falcon 
Scott and his British team, who in November 1911, began a trek 
across the snows of the Antarctic, striving to be the first to 
reach the South Pole. And Dr. Solomon, I can't help but wonder 
if the lessons learned from Scott's and Amundsen's expeditions 
to the South Pole could be applied to this similarly long, 
challenging, and crucial journey to stabilize and reduce 
greenhouse gases.
    Next to Dr. Solomon is Dr. Kevin Trenberth. Dr. Trenberth 
served as a Coordinating Lead Author for Chapter 3 of the 
report, ``Observations, Surface, and Atmospheric Climate 
Change.'' Currently, he is the head of the climate analysis 
section at the National Center for Atmospheric Research (NCAR), 
originally from New Zealand, who obtained his doctorate in 
meteorology in 1972 from MIT. He was named a fellow of the 
American Meteorological Society in 1985 and the American 
Association for the Advancement of Science in 1994. He has 
published over 400 scientific articles or papers, including 40 
books or book chapters and over 175 referee journal articles, 
and he is listed among the top 20 authors in Hyatt citations 
and all of geophysics. He has also recently served as a member 
of the National Oceanic and Atmospheric Administration Climate 
Working Group from 1987 to 2006 and is a member of NOAA's 
Climate Observing System Council and NOAA's Advisory Panel for 
Climate Change Data and Detection.
    At the end of the table is Dr. Gerald Meehl. Dr. Meehl is 
the Coordinating Lead Author for Chapter 10 of the report, 
``Global Climate Projections.'' Dr. Meehl received his Ph.D. in 
climate dynamics from the University of Colorado in 1987. His 
expertise is in the field of climate modeling. He has been a 
scientist on staff at NCAR since 1979. Dr. Meehl has long been 
involved with the IPCC, having been a member of the Working 
Group I Report group since 1989 and has participated in the 
development of several IPCC assessment reports. He is the 
author of more than 140 scientific papers and peer-review 
journals. He has also, since 1979, as a scientist in the 
Climate and Global Dynamics Division, studied the interactions 
between El Nino, the Southern Oscillation, and the Indian 
monsoon, analyzed the results from global-coupled ocean 
atmosphere general circulation models at NCAR, and examined the 
possible effects of increased carbon dioxide, sulfate, 
aerosols, and other forcings on global climate.
    We are really proud to have you three here today. Thank you 
for taking your valuable time to share your conclusions and 
your observations.
    Thank you, Mr. Chairman.
    Chairman Gordon. Thank you, Mr. Udall.
    This is a very, very distinguished panel, and we know this 
has been a hectic period for you, and we do appreciate you 
being here. Each of you will be allowed five minutes, but in 
the spirit of our former Chairman, I don't know whether he was 
embarrassed and left, but Sherry Boehlert was here earlier, he 
would say to witnesses of your nature that 300 seconds is not 
very much to talk about these very serious problems, so we hope 
you will be quick, because we want to have questions, but we 
want you to take the time that you need to make the points that 
need to be.
    So Dr. Solomon, please begin.

                               Panel II:

 STATEMENT OF DR. SUSAN SOLOMON, CO-CHAIR, IPCC, WORKING GROUP 
  I: THE PHYSICAL BASIS OF CLIMATE CHANGE; SENIOR SCIENTIST, 
    EARTH SYSTEM RESEARCH LABORATORY, OFFICE OF OCEANIC AND 
    ATMOSPHERIC RESEARCH, NATIONAL OCEANIC AND ATMOSPHERIC 
          ADMINISTRATION, U.S. DEPARTMENT OF COMMERCE

    Dr. Solomon. Thank you. I would like to thank Chairperson 
Gordon, Ranking Member Hall, and the other Members of the 
Committee for the opportunity to talk with you today on the 
Working Group I Report of the IPCC. I appreciate very much the 
generous introduction by Mr. Udall. I would just like to add 
that I have served as an author on various reports of the IPCC 
beginning in 1992.
    In 2002, I was greatly honored to be formally nominated by 
the United States of America to Co-Chair the Fourth Assessment 
of Working Group I, the part that deals with physical climate 
science.
    The IPCC was established under the World Meteorological 
Organization and the United Nations Environment Program to 
provide regular assessments for policy-makers on the 
scientific, technical, and socio-economic aspects of climate 
change. Today, we will be talking about the scientific aspects 
of climate change, the physical science basis. IPCC does not 
do, nor does it manage, research. It provides assessment 
reports covering the state of scientific understanding based 
upon the scientific literature. Each report is written by 
international experts on a volunteer basis. IPCC's past reports 
have been highly praised by many organizations, such as 
scientific academies around the world, including our own U.S. 
National Academy of Sciences.
    The 152 primary authors of the Working Group I's Fourth 
Assessment Report come from every inhabited continent in the 
world. About 75 percent of those authors did not work on the 
Third Assessment Report, the last previous report, guaranteeing 
a fresh look. About a quarter of the authors are young, in the 
professional sense, having had their highest degree for less 
than 10 years at the time that we started our work. Over 600 
experts participated in two rounds of open review. And in 
addition to the experts, dozens of governments also provided 
formal coordinated reviews, including our own government. In 
total, the Working Group I scientific assessment received over 
30,000 comments. To put those numbers in perspective, a typical 
research paper published in a scientific journal is subject to 
review by two or three experts. It may receive a few dozen 
comments. A distinguished team of 27 review editors, who are 
independent of the author teams, played an oversight role, 
ensuring that all substantive review comments were given 
appropriate consideration. It took over two years to write, 
review, revise and finalize the document, giving us a product 
that we believe is unique in many ways; not least the fact that 
it is not the view of any one scientist or a few scientists but 
rather reflects an extremely broad-ranging synthesis of 
scientific viewpoints. It indicates what is known, and also 
what is not known, and remaining uncertainties.
    A different Working Group covers impacts and adaptation and 
another covers mitigation and policy options. The reports of 
these other two groups will be delivered later this spring.
    And now I would like to briefly turn to some key highlights 
of our own Report, the key messages of this document.
    Greenhouse gases have increased markedly since 1750 and are 
now at levels unprecedented in many thousands of years. The 
warming is unequivocal. Our planet is warming. That is evident 
in many different types of observations. Most of the warming of 
the past 50 years is very likely due to greenhouse gas 
increases. We believe that has a 9-out-of-10 chance based on a 
very careful detailed assessment that accounts for solar and 
volcanic effects, that takes into account many factors, 
including the simple fact that the recent years have been 
remarkably warm, and the chances of that happening at random 
are quite small.
    We are already committed to further warming. Even if we 
were to stabilize all greenhouse gases now, instead of having 
continuing increases. And in that regard, the rate of increase 
of carbon dioxide of the past 10 years was the largest since 
direct measurements began in 1960.
    Continued emissions at or above current rates will very 
likely lead to larger changes in the 21st century than those of 
the 20th. The effects expected include: more heavy rain, more 
drought, more heat waves, and more sea level rise. How much 
depends on how much we choose to emit on a global basis.
    Sea level rise is expected to increase due to expansion of 
water in a warmer world. Changes in ice sheets are currently 
contributing about 12 percent to the total sea level rise of 
the past decade. That could grow or it could decrease in the 
future. And I will leave it to Dr. Alley to talk more about 
that.
    And thank you very, very much for the invitation and for 
your attention.
    [The prepared statement of Dr. Solomon follows:]
                  Prepared Statement of Susan Solomon
    I thank Chairperson Gordon, Ranking Member Hall, and the other 
Members of the Committee for the opportunity to speak with you today on 
the Working Group I report of the Intergovernmental Panel on Climate 
Change 2007 Report (IPCC, 2007). My name is Susan Solomon and I am a 
Senior Scientist at NOAA's Earth System Research Laboratory in Boulder, 
Colorado. I've been a scientist at NOAA for more than 26 years. Much of 
my work over that time has focused on understanding the cause of ozone 
depletion. In 2000, I received this nation's highest scientific award, 
the National Medal of Science, in recognition of that work. I've also 
been honored with membership in the U.S. National Academy of Sciences 
and I am a foreign associate of the French Academy of Sciences and the 
Acadamiae Europaea. In addition to my research on ozone depletion, I 
also do personal research on climate change, in particular on the range 
of chemicals that contribute to climate change. I'm the author or co-
author of more than 150 scientific publications, and I've served as an 
author on various reports of the Intergovernmental Panel on Climate 
Change beginning in 1992.
    In 2002, I had the honor of being formally nominated by the United 
States of America to co-chair Working Group I, the part of the IPCC 
that deals with physical climate science. I was selected by the IPCC 
Panel of governments to serve in that role, and for almost the past 
five years have accordingly co-chaired the process that resulted in the 
2007 Working Group I Assessment Report, together with Dr. Qin Dahe of 
China. We are assisted by six able vice-chairs from around the world 
and by a technical support unit that provides logistical and related 
functions.
    The Intergovernmental Panel on Climate Change was established under 
the auspices of the World Meteorological Organization and the United 
Nations Environment Program to provide regular assessments for policy-
makers of the scientific, technical and socio-economic aspects climate 
change. IPCC does not do or manage research. It provides assessment 
reports covering the state of scientific understanding based upon the 
scientific literature. Each report is written by international experts 
on a volunteer basis. IPCC has produced its major assessments every 
five to six years since 1990, and the 2007 report is the fourth in that 
series. The Working Group Co-Chairs and Vice-Chairs select authors on 
the basis of their scientific publications and products from among 
nominees proposed by governments, with due regard for geographic 
balance. IPCC's reports have been highly praised by many organizations 
such as scientific academies around the world including our own U.S. 
National Academy of Sciences.
    The 152 authors of the Working Group I Fourth Assessment Report 
hail from every inhabited continent in the world. About 75 percent of 
these authors did not work on the previous 2001 report. About a quarter 
of the authors are young in the professional sense, having had their 
highest degree for less than 10 years at the time we began our work. 
Over 400 other scientists have served as contributing authors. Over 600 
experts participated in two rounds of open review. In addition to the 
experts, dozens of governments also provided formal coordinated 
reviews. In total, the Working Group I assessment received over 30,000 
comments. To put these numbers in perspective, a typical research paper 
published in a scientific journal is subject to review by two or three 
experts. It may receive a few dozen comments. A distinguished team of 
27 review editors, who are independent of the author teams, played an 
oversight role ensuring that all substantive review comments were given 
appropriate consideration. It took over two years to write, review, 
revise and finalize the document. The product is unique in many ways, 
not least the fact that it is not the view of any one scientist or a 
few scientists but rather reflects an extremely broad-ranging synthesis 
of scientific viewpoints.
    A different Working Group (Working Group II), covers impacts and 
adaptation and another (Working Group III) covers mitigation and policy 
options. The reports of these other two groups are due to be released 
later this spring. There will also be a Synthesis Report released in 
November, 2007, which endeavors to provide a synthesis of all three 
Working Group reports.
    The Summary for Policy-makers of the Working Group I was approved 
by the governments of the IPCC Panel in Paris last week. That document 
is appended here as the scientific basis of my testimony.






























                      Biography for Susan Solomon
    Susan Solomon is widely recognized as one of the leaders in the 
field of atmospheric science. Since receiving her Ph.D. degree in 
chemistry from the University of California at Berkeley in l98l, she 
has been employed by the National Oceanic and Atmospheric 
Administration as a research scientist. Her scientific papers have 
provided not only key measurements but also theoretical understanding 
regarding ozone destruction, especially the role of surface chemistry. 
In l986 and l987, she served as the Head Project Scientist of the 
National Ozone Expedition at McMurdo Station, Antarctica and made some 
of the first measurements there that pointed towards 
chlorofluorocarbons as the cause of the ozone hole. In l994, an 
Antarctic glacier was named in her honor in recognition of that work. 
In March of 2000, she received the National Medal of Science, the 
United States' highest scientific honor, for ``key insights in 
explaining the cause of the Antarctic ozone hole.'' In 2004 she 
received the prestigious Blue Planet Prize for ``pioneering research 
identifying the causative mechanisms producing the Antarctic ozone 
hole.''
    She is the recipient of many other honors and awards, including the 
J.B. MacElwane award of the American Geophysical Union, the Department 
of Commerce Gold Medal for Exceptional Service, the Henry G. Houghton 
and Carl-Gustaf Rossby awards of the American Meteorological Society 
for excellence in research, the Arthur S. Flemming Award for 
exceptional government service, the Common Wealth Award of the Common 
Wealth Trust, and the ozone award from the United Nations Environment 
Programme. In l992, R&D Magazine honored her as its ``scientist of the 
year.'' She is a recipient of honorary doctoral degrees from Tulane 
University, Williams College, the State University of New York at Stony 
Brook, the Illinois Institute of Technology, the University of Miami, 
the University of Colorado, and the University of East Anglia in the 
UK. She is a member of the U.S. National Academy of Sciences and a 
Foreign Associate of both the French Academy of Sciences and the 
European Academy of Sciences. Her current research includes climate 
change and ozone depletion, and she serves as Co-Chair of Working Group 
I of the Intergovernmental Panel on Climate Change (IPCC), providing 
scientific information to the United Nations Framework Convention on 
Climate Change.

    Chairman Gordon. Thank you, Doctor. And now Dr. Trenberth.

STATEMENT OF DR. KEVIN E. TRENBERTH, COORDINATING LEAD AUTHOR, 
  IPCC, WORKING GROUP I, CHAPTER 3: OBSERVATIONS: SURFACE AND 
  ATMOSPHERIC CLIMATE CHANGE; HEAD, CLIMATE ANALYSIS SECTION, 
            NATIONAL CENTER FOR ATMOSPHERIC RESEARCH

    Dr. Trenberth. Thank you, Mr. Chairman. I thank 
Representative Udall for introducing me, and as he said, I am 
the Coordinating Lead Author of Chapter 3 of the IPCC Report, 
which Susan has introduced, and that deals with the 
observations in the atmosphere and at the surface and also does 
a synthesis across all observations, and that is what I am 
going to focus on here.
    And essentially, what we have done in the IPCC, perhaps as 
a medical analogy, is to do a diagnosis of the vital signs of 
the planet Earth. And what we have found, then, is that the 
planet is running a fever, so to speak, and the prognosis is 
that it is apt to become much worse.
    Now to paraphrase the Report, ``Warming of the climate 
system is unequivocal.'' That is actually a quote, and it is 
very likely due to human activities.
    In my written testimony, a summary is given of the main 
findings for Chapter 3, and it is linked to the other 
observational chapters. And the overall summary statement of 
one of the highlight points in the policy-maker's summary is, 
to quote, ``Warming of the climate system is unequivocal, as is 
now evident from observations of increases in global-averaged 
air and ocean temperatures, widespread melting of snow and ice, 
and rising global mean sea level.'' And then there is another 
item, which goes on to elaborate on more regional aspects and 
other variables as well. And that is what I am going to focus 
on in my following remarks.
    And so we say that the warming of the climate system is 
unequivocal because it is now clear from an increasing body of 
evidence showing discernable, physically-consistent changes. In 
other words, we can relate all of these changes to warming. And 
there are many more variables listed than in the brief IPCC 
statement. Now these include, firstly, global average air 
temperature, and I am going to come back to that.
    If I could have the first slide, if I might, please.
    
    

    This just shows you global warming is unequivocal, and what 
I have done here is to put the main bullets that I am going to 
talk about on here, the different variables and the items.
    And so as well as global surface air temperature, there are 
the air temperatures above the surface, and this refers to what 
is called often the satellite temperatures. Sea surface 
temperatures are also increasing, and they are very important 
for things like storms over the oceans and hurricanes. 
Subsurface ocean water temperatures are increasing, below the 
surface. We can measure those, and that leads to expansion of 
the ocean, contributing to sea level. There is widespread 
melting of snow in the Northern Hemisphere. There are decreases 
in Arctic sea ice extent and thickness. There are decreases in 
glacier and small ice cap extent and mass. And as a result, 
there is a global mean sea level rise at a rate in the last 12 
years of more than a foot a century, and that is contributed to 
by the expansion of the ocean and the melting of land ice.
    The observed surface warming at both global and continental 
scales is also consistent with the reduced duration of freeze 
seasons, less frost, increases in heat waves, and increased 
atmospheric water vapor in the atmosphere, and this is very 
important, because it feeds into heavier precipitation events, 
and this includes, ironically, perhaps, heavier snowfall 
events, because the atmosphere can hold more water vapor when 
it is warmer.
    There are also changes in precipitation around the world, 
and part of that leads to increases in drought, especially in 
the tropics, and this is already evident in the observational 
record. Increases in the intensity of hurricane activity are 
also evident, and there are changes in the large-scale patterns 
of atmospheric winds, changes in where storms are actually 
going in middle latitudes.
    So if I can look at the second--or the next slide, here it 
is here.



    This is the global average temperatures, the time series 
from 1850 up until 2006. The dots are the annual values. The 
heavy blue curve is the decadal smooth values, and the yellow 
is the sort of uncertainty around that. And what we frequently 
do with a curve like this is to put a straight line through it. 
And if we do that, you get this line here for the last 150 
years, and on the bottom right, I don't know if you can see the 
numbers here, there is actually--the rate of change is given. 
And what we can also do is then put a line through it for the 
last 100 years, and it looks like this. And you can see that it 
is considerably steeper. And then for the last 50 years, it 
looks like this. And then for the last 25 years, it looks like 
this. And listed at the top there is a list of the last 12 
years. Indeed, 11 out of the last 12 years are the warmest on 
record.
    And so the rate of warming has increased over time, and 
indeed, this is the direction we are going in the immediate 
future.
    And so the Fourth Assessment Report of IPCC finds that the 
Earth is warming and that the major components of the Earth's 
climate system are already responding to that warming.
    Now the wide variety of observations gives a very high 
degree of confidence in the overall findings, and moreover, 
these changes are now simulated in climate models for the past 
100 years to a reasonable degree, as my colleague Jerry Meehl 
is likely to talk about, and this adds confidence to the future 
projections.
    Mr. Chairman, one interpretation of this is that, you know, 
as with a fiscal budget, we are running a deficit and building 
a debt for the future generations. And our current generation 
is now running what we might refer to as an environmental 
deficit, and it will, indeed, be paid for by the future 
generations.
    I appreciate the opportunity to address the Committee 
concerning the science of global climate change, and I look 
forward to answering any questions.
    Thank you.
    [The prepared statement of Dr. Trenberth follows:]
                Prepared Statement of Kevin E. Trenberth

                    Observations of climate change:

                        The 2007 IPCC Assessment

Summary

    Following a detailed diagnosis of the vital signs of the planet 
Earth, it has become evident that the planet is running a ``fever'' and 
the prognosis is that it is apt to get much worse. ``Warming of the 
climate system is unequivocal'' and it is ``very likely'' due to human 
activities. This is the verdict of the Fourth Assessment Report of the 
Intergovernmental Panel on Climate Change (IPCC), known as AR4. In the 
following, I provide a brief introduction to the IPCC and its 
processes. A summary is then given of the main findings from the AR4 
for Chapter 3, ``Observations: Surface and Atmospheric Climate 
Change,'' and its links to other observational chapters. Warming of the 
climate system is unequivocal as is now clear from an increasing body 
of evidence showing discernible physically consistent changes. These 
include increases in global average air temperature; atmospheric 
temperatures above the surface, surface and sub-surface ocean water 
temperature; widespread melting of snow; decreases in Arctic sea-ice 
extent and thickness; decreases in glacier and small ice cap extent and 
mass; and rising global mean sea level. The observed surface warming at 
global and continental scales is also consistent with reduced duration 
of freeze seasons; increased heat waves; increased atmospheric water 
vapor content and heavier precipitation events; changes in patterns of 
precipitation; increased drought; increases in intensity of hurricane 
activity, and changes in atmospheric winds. That is, the IPCC Fourth 
Assessment finds that the Earth is warming, and that major components 
of the Earth's climate system are already responding to that warming. 
This wide variety of observations gives a very high degree of 
confidence to the overall findings. Moreover these changes are now 
simulated in climate models for the past 100 years to a reasonable 
degree, adding confidence to future projections. The summary is 
followed by a few personal remarks about the meaning of these findings.

Introduction

    My name is Kevin Trenberth.\1\ I am a senior scientist and the Head 
of the Climate Analysis Section at NCAR, the National Center for 
Atmospheric Research.\2\ I have authored over 400 publications in the 
area of climate, and given hundreds of talks on the subject. I am among 
the most highly cited researchers in all of geophysics. I am especially 
interested in global-scale climate dynamics; the observations, 
processes and modeling of climate changes from inter-annual to 
centennial time scales. I have particular expertise in El Nino, the 
hydrological and energy cycles, and hurricanes and climate change. I 
have served on many national and international committees including 
National Research Council/National Academy of Science committees, 
panels and/or boards. I co-chaired the international Climate 
Variability and Predictability (CLIVAR) Scientific Steering Group of 
the World Climate Research Programme (WCRP) from 1996 to 1999 and I 
have served as a member and officer of the Joint Scientific Committee 
that oversees the WCRP as a whole from 1998 to 2006. I chair the WCRP 
Observations and Assimilation Panel. I have been involved in global 
warming science and I have been extensively involved in the 
Intergovernmental Panel on Climate Change (IPCC) scientific assessment 
activity as a Lead Author of individual chapters, the Technical 
Summary, and Summary for Policy-makers (SPM) of Working Group (WG) I 
for both the Second and Third Assessment Reports (SAR and TAR; IPCC 
1996, 2001). I am a Coordinating Lead Author of Chapter 3 of the Fourth 
IPCC Assessment (AR4) that deals with observations of the surface and 
atmospheric climate change.
---------------------------------------------------------------------------
    \1\ Any opinions, findings, conclusions, or recommendations 
expressed in this publication are those of the author and do not 
necessarily reflect those of the National Science Foundation.
    \2\ The National Center for Atmospheric Research (NCAR) is 
sponsored by the National Science Foundation.
---------------------------------------------------------------------------
    The IPCC is a body of scientists from around the world convened by 
the United Nations jointly under the United Nations Environment 
Programme (UNEP) and the World Meteorological Organization (WMO) and 
initiated in 1988. Its mandate is to provide policy-makers with an 
objective assessment of the scientific and technical information 
available about climate change, its environmental and socio-economic 
impacts, and possible response options. The IPCC reports on the science 
of global climate and the effects of human activities on climate in 
particular. Major assessments were made in 1990, 1995, 2001, and now 
2007. Each new IPCC report reviews all the published literature over 
the previous five to seven years, and assesses the state of knowledge, 
while trying to reconcile disparate claims and resolve discrepancies, 
and document uncertainties.
    WG I deals with how the climate has changed and the possible 
causes. It considers how the climate system responds to various agents 
of change and our ability to model the processes involved as well as 
the performance of the whole system. It further seeks to attribute 
recent changes to the possible various causes, including the human 
influences, and thus it goes on to make projections for the future. WG 
II deals with impacts of climate change, vulnerability, and options for 
adaptation to such changes, and WG III deals with options for 
mitigating and slowing the climate change, including possible policy 
options. Each WG is made up of participants from the United Nations 
countries, and for the 2007 assessment there are over 450 Lead Authors, 
800 contributing authors, and over 2,500 reviewers from over 130 
countries. In my chapter, as well as the two Coordinating Lead Authors, 
we have 10 Lead Authors, 66 contributing authors, about 100 pages of 
text, 126 figure panels in 47 figures, and 863 references. The IPCC 
process is very open. Two major reviews were carried out in producing 
the report, and climate ``skeptics'' can and do participate, some as 
authors. For our chapter we received over 2230 comments on the expert 
review and 1270 on the governmental review, all of which were responded 
to in writing and by changing the report. The process is overseen by 
two Review Editors. The strength is that it is a consensus report. The 
SPM was approved line by line by governments in a major meeting in 
Paris from 29 January to 1 February, 2007. The rationale is that the 
scientists determine what can be said, but the governments help 
determine how it can best be said. Negotiations occur over wording to 
ensure accuracy, balance, clarity of message, and relevance to 
understanding and policy. The latest report (IPCC 2007) reaffirms in 
much stronger language that the climate is changing in ways that cannot 
be accounted for by natural variability and that ``global warming'' is 
happening.

Observed Climate Change

    The iconic summary statement of the observations section of the 
IPCC (2007) report is ``Warming of the climate system is unequivocal, 
as is now evident from observations of increases in global average air 
and ocean temperatures, widespread melting of snow and ice, and rising 
global mean sea level.'' The language here is carefully chosen to 
reinforce the view that

        1)  There are multiple lines of evidence from many variables

        2)  There is a wide body of evidence and multiple analyses of 
        each variable

        3)  The variables and evidence are physically consistent with 
        warming

        4)  The human signal has clearly emerged from noise of natural 
        variability, i.e., it is large.

    Since the TAR, progress in understanding how the current climate is 
changing in space and in time has been gained through improvements and 
extensions of numerous data sets and data analyses, broader 
geographical coverage, better understanding of uncertainties, and a 
wider variety of measurements. Increasingly comprehensive observations 
are available for glaciers and snow cover since the 1960s, and for sea 
level and ice sheets since about the past decade. Numerous changes in 
climate have been observed at the scales of continents or ocean basins. 
These include wind patterns, precipitation, ocean salinity, sea ice, 
ice sheets, and aspects of extreme weather.

a. Temperature and related
    Instrumental observations over the past 157 years show that 
temperatures at the surface (Fig. 1) have risen globally, with 
important regional variations. For the global average, warming in the 
last century has occurred in two phases, from the 1910s to the 1940s 
(0.35+C or 0.63+F), and more strongly from the 
1970s to the present (0.55+C or 1.0+F) at a rate 
of about 0.16+C (0.3+F) per decade. An increasing 
rate of warming has taken place over the last 25 years, and 11 of the 
12 warmest years on record have occurred in the past 12 years. Indeed, 
the six years since the TAR are among the seven warmest years on 
record. The total warming since the 1800s is about 0.76+C 
(1.4+F). Globally, 2006 ranks sixth and it was the warmest 
on record in the United States. Sea surface temperatures (SSTs) are 
also increasing, however land areas are warming much faster than the 
oceans since 1970.



    Two possible issues with the surface temperature record--urban heat 
island effects, and discrepancies with balloon-based and satellite 
measurements--have been extensively studied in the 2007 IPCC report. 
The urban heat island effects are real but local, and have been found 
to have a negligible influence on the overall surface temperature 
record. New analyses of balloon-borne and satellite measurements of 
lower- and mid-tropospheric temperature show warming rates that are 
similar to the surface temperature record and consistent within their 
respective uncertainties, largely reconciling a discrepancy noted in 
the TAR. The 2007 IPCC report essentially removes these two issues as 
serious sources of uncertainty for the global surface temperature 
record.
    Regional temperature observations do not always track the global 
average warming because of atmospheric wave patterns, as well as 
increased natural variability at smaller geographic scales. For 
example, the eastern half of the United States has not warmed as much 
as other areas, especially during the daytime, owing to increases in 
cloud and precipitation associated with changes in atmospheric 
circulation as the climate changes. On the other hand, average Arctic 
temperatures increased at almost twice the global average rate in the 
past 100 years and also since 1960. However, Arctic temperatures have 
high decadal variability and a warm period was observed from 1925 to 
1945, but that was focused in the North Atlantic and not global as in 
the recent warming.
    Since 1950, the number of heat waves globally has increased and 
widespread increases have occurred in the numbers of warm nights. Cold 
days, cold nights and frost have generally become rarer.
    Decreases are found in the length of the freeze season of river and 
lake ice. Temperature at the top of the permafrost layer has increased 
by up to 3+C since the 1980s in the Arctic. The maximum area 
covered by seasonally frozen ground has decreased by about seven 
percent in the Northern Hemisphere since 1900 and this value is up to 
15 percent in spring.
    The average temperature of global ocean water from the surface to a 
depth of 700m increased significantly from 1961 to 2003, indicating 
that the ocean is absorbing most of the heat being added to the climate 
system. This causes seawater to expand and is estimated to have 
contributed 0.42mm per year to the average sea level rise from 1961 to 
2003, and 1.8mm per year from 1993 to 2003.
    Sea-ice extents have decreased in the Arctic since 1978, 
particularly in spring and summer (7.4 percent per decade), and 
patterns of the changes are consistent with regions showing a 
temperature increase, although changes in winds are also a major 
factor. Sea-ice extents were at record low values in 2005, which was 
also the warmest year since records began in 1850 for the Arctic north 
of 65 N. There have also been decreases in sea-ice thickness. In 
contrast to the Arctic, Antarctic sea ice does not exhibit any 
significant trend since the end of the 1970s, which is consistent with 
the lack of trend in surface temperature south of 65 S over that 
period. However, along the Antarctic Peninsula, where significant 
warming has occurred, progressive break up of ice shelves has occurred 
beginning in the late 1980s, culminating in the break up of the Larsen-
B ice shelf in 2002.
    The observed surface temperature increases are consistent with the 
observed nearly worldwide reduction in glacier and small ice cap mass 
and extent in the 20th century. In addition, flow speed has recently 
increased for some Greenland and Antarctic outlet glaciers, which drain 
ice from the interior, and melting of Greenland has increased after 
about 2000. Glaciers and ice caps respond not only to temperatures but 
also to changes in precipitation, and both winter accumulation and 
summer melting have increased over the last half century in association 
with temperature increases. In some regions moderately increased 
accumulation observed in recent decades is consistent with changes in 
atmospheric circulation and associated increases in winter 
precipitation (e.g., southwestern Norway, parts of coastal Alaska, 
Patagonia, and the South Island of New Zealand) even though increased 
ablation has led to marked declines in mass balances in Alaska and 
Patagonia. Tropical glacier changes are synchronous with higher 
latitude ones and all have shown declines in recent decades. Decreases 
in glaciers and ice caps contributed to sea level rise by 0.5mm per 
year from 1961 to 2003 and 0.8mm per year from 1993 to 2003. Taken 
together, shrinkage of the ice sheets of Greenland and Antarctica has 
contributed 0.4mm per year to sea level rise over 1993 to 2003.
    Global average sea level rose at an average rate of 1.8mm per year 
over 1961 to 2003. The rate was faster during 1993-2003, when truly 
global values have been measured from altimeters in space, at about 
3.1mm per year. Hence about 60 percent of this is from ocean warming 
and expansion, and 40 percent is from melting land ice, adding to the 
ocean volume. The observation of consistent sea level rise over several 
decades, and also an increasing rate of sea level rise in the last 
decade or so, is probably the single best metric of the cumulative 
global warming that we have experienced to date. There is really no 
explanation other than global warming for the observed sea level rise.
    The average atmospheric water vapor content has increased over land 
and ocean as well as in the upper troposphere, and over the global 
oceans this is estimated to be four percent since 1970. The increase is 
broadly consistent with the extra water that warmer air can hold and 
amounts to a fairly constant relative humidity. The added water vapor 
also adds to the greenhouse effect and roughly doubles that due to 
carbon dioxide, providing a powerful positive feedback to climate 
change.
    The observed surface warming at global and continental scales is 
consistent with observed changes in sub-surface ocean water 
temperature; decreases in sea-ice extent and thickness; decreases in 
glacier and small ice cap extent and mass; sea-level rise; reduced 
duration of freeze seasons, increased heat waves; and increased 
atmospheric water vapor content. That is, the IPCC Fourth Assessment 
finds that the Earth is warming, and that major components of the 
Earth's climate system are already responding to that warming. This 
wide variety of observations gives a very high degree of confidence to 
the overall findings.

b. Precipitation and related
    The 2007 IPCC report finds that changes are occurring in the 
amount, intensity, frequency, and type of precipitation in ways that 
are also consistent with a warming planet. These aspects of 
precipitation generally exhibit large natural variability (compared to 
temperature trends), and El Nino and changes in atmospheric circulation 
patterns have a substantial influence, making it harder to detect 
trends in the observational record.
    A key ingredient in changes in character of precipitation is the 
observed increase in water vapor and thus the supply of atmospheric 
moisture to all storms, increasing the intensity of precipitation 
events. Indeed, widespread increases in heavy precipitation events and 
risk of flooding have been observed, even in places where total amounts 
have decreased. Hence the frequency of heavy rain events has increased 
in most places but so too has episodic heavy snowfall events that are 
thus associated with warming. Snow cover has decreased in many Northern 
Hemisphere regions, particularly in spring, and more precipitation is 
falling as rain instead of snow. These changes are consistent with 
changes in permafrost, noted above.
    Long-term trends from 1900 to 2005 have been observed in total 
precipitation amounts over many large regions. Significantly increased 
precipitation has been observed in eastern parts of North and South 
America, northern Europe and northern and central Asia. Drying has been 
observed in the Sahel, the Mediterranean, southern Africa and parts of 
southern Asia. Precipitation is highly variable spatially and 
temporally. Robust long-term trends have not been observed for other 
large regions. The pattern of precipitation change is one of increases 
generally at higher northern latitudes (because as the atmosphere warms 
it holds more moisture) and drying in the tropics and subtropics over 
land. Basin-scale changes in ocean salinity provide further evidence of 
changes in the Earth's water cycle, with freshening at high latitudes 
and increased salinity in the subtropics.
    More intense and longer droughts have been observed over wider 
areas since the 1970s, particularly in the tropics and subtropics. 
Increased drying due to higher temperatures and decreased precipitation 
have contributed to these changes, with the latter the dominant factor. 
The regions where droughts have occurred are determined largely by 
changes in sea surface temperature (SST), especially in the tropics 
(such as during El Nino), through changes in the atmospheric 
circulation and precipitation. In the western United States, 
diminishing snow pack and subsequent summer soil moisture reductions 
have also been a factor. In Australia and Europe, direct links to 
warming have been inferred through the extreme nature of high 
temperatures and heat waves accompanying drought.
    Satellite records suggest a global trend towards more intense and 
longer lasting tropical cyclones (including hurricanes and typhoons) 
since about 1970, correlated with observed warming of tropical SSTs. 
There is no clear trend in the annual number of tropical cyclones 
globally although a substantial increase has occurred in the North 
Atlantic after 1994. There are concerns about the quality of tropical 
cyclone data, particularly before the satellite era. Further, strong 
multi-decadal variability is observed and complicates detection of 
long-term trends in tropical cyclone activity.

c. Synthesis across variables
    In summary, global mean temperatures have increased since the 19th 
century, especially since the mid-1970s. Temperatures have increased 
nearly everywhere over land, and SSTs have also increased, reinforcing 
the evidence from land. However, global warming does not mean that 
temperatures increase steadily or uniformly, indeed temperatures have 
increased neither monotonically, nor in a spatially uniform manner, 
especially over shorter time intervals. The atmospheric circulation has 
also changed: in particular increasing westerly wind flow is observed 
in most seasons in both hemispheres. In the Northern Hemisphere this 
brought milder maritime air into Europe and much of high-latitude Asia 
from the North Atlantic in winter, enhancing warming there. In the 
Southern Hemisphere, where the ozone hole has played a role, it has 
resulted in cooling over 1971-2000 for parts of the interior of 
Antarctica but large warming in the Antarctic Peninsula region and 
Patagonia. Temperatures generally have risen more than average where 
flow has become more poleward, and less than average or even cooled 
where flow has become more equatorward, reflecting atmospheric patterns 
of variability.
    Over land in low latitudes and in summer more generally, there is a 
strong tendency for either hot and dry or cool and wet. Hence areas 
that have become wetter, such as the eastern United States and 
Argentina, have not warmed as much as other land areas. Increased 
precipitation is associated with increases in cloud and surface 
wetness. Thus more heat goes into increased evapotranspiration and less 
into raising temperature at the surface in wetter conditions.
    The three main ocean basins are unique and contain very different 
wind systems, SST patterns and ocean currents, leading to vastly 
different variability associated, for instance, with El Nino in the 
Pacific, and the ocean currents including the Gulf Stream in the 
Atlantic. Consequently the oceans have not warmed uniformly, especially 
at depth. SSTs in the tropics have warmed at different rates and help 
drive, through coupling with tropical convection and winds, distinctive 
wave patterns known as teleconnections around the world. This has 
changed the atmospheric circulation and the monsoons. Changes in 
precipitation and storm tracks are not as well documented but clearly 
respond to these changes on inter-annual and decadal timescales. When 
precipitation increases over the ocean, as it has in recent years in 
the tropics, it decreases over land, although it has increased over 
land at higher latitudes. Droughts have increased over many tropical 
and mid-latitude land areas, in part because of decreased precipitation 
over land since the 1970s but also from increased drying arising from 
increased atmospheric demand associated with warming.
    Many of these observed changes are now simulated in climate models 
run for the past 100 years, adding confidence to understanding of the 
relationship with the agents that alter the climate, and human-induced 
changes in atmospheric composition, in particular, as is documented in 
other IPCC chapters.

Some implications

    The scientific understanding of climate change is now sufficiently 
clear to show that specific global and regional changes resulting from 
global warming are already upon us. Uncertainties remain, and new 
efforts at reprocessing past satellite records for phenomena such as 
hurricanes are required, but the 2007 IPCC report definitively shows 
that the climate is changing. ``Warming is unequivocal'' and it is 
``very likely'' caused by human activities.
    In my personal opinion as a climate scientist, the IPCC report 
strongly implies the need for a three pronged approach of mitigation, 
adaptation, and maintaining and improving climate observing and 
information systems.
    While there are uncertainties (although these cut both ways) and 
some changes arising from global warming may be benign or even 
beneficial, at least in some places and in the short run, the IPCC 
report shows that the rate of change as projected exceeds anything seen 
in nature in the past 10,000 years. Moreover, the inertia of the 
climate system and the long life of carbon dioxide in the atmosphere 
mean that we are already committed to a significant level of climate 
change. I believe that mitigation actions are certainly needed to 
significantly reduce the build-up of greenhouse gases in the atmosphere 
and lessen the magnitude and rate of climate change.
    At the same time, the 2007 IPCC report makes clear that even 
aggressive mitigation would yield benefits many decades in the future, 
and that no amount of mitigation can avoid significant climate change. 
I believe it is apt to be disruptive in many ways. Hence it is also 
vital to plan to cope with the changes, such as enhanced droughts, heat 
waves and wild fires, and stronger downpours and risk of flooding. 
Managing water resources will be a major challenge in the future. 
Adapting to climate change and reducing vulnerability is essential. 
This means that we should adapt to climate change by planning for it 
and making better predictions of likely outcomes on several time 
horizons.
    Finally, although not reported by the IPCC, my experience in 
working with observations of climate change has led me to urge the 
Committee to address the considerable shortcomings in our observing 
systems. Weather observing systems are continually used for climate 
purposes for which they were not designed. Moreover, weather stations 
come and go and changes are made without regard to the effect on the 
climate record. Changes in observing systems, especially from 
satellites, as new satellites and instruments are launched, create 
artifacts in the climate record. Loss of Earth observing satellites is 
also of concern, as documented in the recent National Research Council 
(2007) decadal survey. Ground based observations are not being 
adequately kept up in many countries. Calibration of climate records is 
critical. Small changes over long times are characteristic of climate 
change but they occur in the midst of large variations associated with 
weather and natural climate variations such as El Nino. Yet the climate 
is changing and an imperative is to track the changes and the causes as 
they occur. We need to build a system based on these observations to 
inform decision-makers on what is happening, and why, and what the 
predictions are for the future on several time horizons.
    I appreciate the opportunity to address the Committee concerning 
the science of global climate change, and look forward to answering any 
questions you may have today or in the future.

References and some bibliography

IPCC, 1996: Climate Change 1995: The Science of Climate Change. Eds. 
        J.T. Houghton et al., Cambridge University Press, Cambridge, 
        U.K. 572 pp.
IPCC, 2001: Climate Change 2001: The Scientific Basis. Eds. J.T. 
        Houghton, et al., Cambridge University Press, Cambridge, U.K. 
        881 pp.
IPCC, 2007: Climate Change 2007: The Scientific Basis. Eds. S. Solomon, 
        et al., Cambridge University Press, Cambridge, U.K. (in press).
Karl, T.R., and K.E. Trenberth, 2003: Modern global climate change. 
        Science, 302, 1719-1723.
Karl, T.R., and K.E. Trenberth, 2006: Modern global climate change. 
        Science Magazine's State of the Planet, Donald Kennedy and the 
        editors of Science magazine, Eds., Island Press, 88-98.
National Research Council, 2007: Earth Science and Applications from 
        Space: National Imperatives for the Next Decade and Beyond. The 
        National Academies Press.
Trenberth, K.E., 2001: Stronger evidence for human influences on 
        climate: The 2001 IPCC Assessment. Environment, 43, 4(May), 8-
        19.
Trenberth, K.E., T.R. Karl and T.W. Spence, 2002: The need for a 
        systems approach to climate observations. Bull. Amer. Meteor. 
        Soc., 83, 1593-1602.
Trenberth, K.E., 2005: Uncertainty in hurricanes and global warming. 
        Science, 308, 1753-1754.
Trenberth, K.E., and D.J. Shea, 2006: Atlantic hurricanes and natural 
        variability in 2005. Geophys. Res. Lett., 33, L12704, 
        doi:10.1029/2006GL026894.
                    Biography for Kevin E. Trenberth
    Dr. Kevin Trenberth is Head of the Climate Analysis Section at the 
National Center for Atmospheric Research (NCAR) in Boulder, CO. From 
New Zealand, he completed a first class honors degree in mathematics at 
the University of Canterbury, Christchurch, New Zealand, and obtained 
his Sc.D. in meteorology in 1972 from Massachusetts Institute of 
Technology, Cambridge, Massachusetts. He was previously employed as a 
research scientist in the New Zealand Meteorological Service and was a 
Professor at the University of Illinois for nearly seven years prior to 
joining NCAR in 1984.
    He was named a Fellow of the American Meteorological Society (AMS) 
in 1985, the American Association for Advancement of Science (AAAS) in 
1994, the American Geophysical Union in 2006 and an Honorary Fellow of 
the New Zealand Royal Society in 1995. In 2000 he received the Jule G. 
Charney award from the AMS and in 2003 he was given the NCAR 
Distinguished Achievement Award. He has served as an editor and 
associate editor for several professional journals. He edited a 788 
page book, Climate System Modeling (1992). He has published over 400 
scientific articles or papers, including 40 books or book chapters, and 
over 175 refereed journal articles and has given many invited 
scientific talks as well as appearing in a number of television, radio 
programs and newspaper articles. He is listed among the top 20 authors 
in highest citations in all of geophysics.
    Trenberth has served on a number of national and international 
advisory committees and panels including many panels, committees and a 
board of the National Academy of Sciences. Trenberth has been prominent 
in the Intergovernmental Panel on Climate Change (IPCC) Scientific 
Assessment activities, was a Convening Lead Author for the 1995 
Scientific Assessment and Lead Author for the 2001 assessment 
(including for the Technical Summary and Summary for Policy-makers) and 
is a Coordinating Lead Author of the 2007 assessment. He has recently 
served as a member of the National Oceanic and Atmospheric 
Administration (NOAA) Climate Working Group (from 1987 to 2006), and is 
a member of NOAA's Climate Observing System Council, and NOAA's 
Advisory Panel for Climate Change Data and Detection. He also recently 
served on the Joint Scientific Committee of the World Climate Research 
Programme (WCRP) from 1999 to 2006 and was an officer from 2003 to 
2006, and he chairs the WCRP Observations and Assimilation Panel. He 
served on the Scientific Steering Group for the WCRP Climate 
Variability and Predictability (CLIVAR) program and was Co-Chair from 
1995 to 1999.
    See http://www.cgd.ucar.edu/cas/trenbert.html

    Chairman Gordon. Dr. Alley.

 STATEMENT OF DR. RICHARD B. ALLEY, LEAD AUTHOR, IPCC, WORKING 
  GROUP I, CHAPTER 4: OBSERVATIONS: CHANGES IN SNOW, ICE AND 
FROZEN GROUND; EVAN PUGH PROFESSOR OF GEOSCIENCES AND ASSOCIATE 
OF THE EARTH AND ENVIRONMENTAL SYSTEMS INSTITUTE, PENNSYLVANIA 
                        STATE UNIVERSITY

    Dr. Alley. Thank you, Mr. Chairman, honored Members.
    As Dr. Trenberth pointed out, observations of snow and ice 
show that melting is now widespread. We see this in snow cover 
in the north. We see this in the Arctic sea ice. We see it in 
most of the glaciers of the world. We see it in frozen ground 
and permafrost. We see it in the great ice sheets of Greenland 
and Antarctica. And we see it even where there is more snow 
falling. And so it is really hard to blame a loss of ice on 
loss of snow if there is more snow in some places, and yet it 
is melting faster. And so it is very clear that warming is 
implicated in this.
    I would like to focus especially on the large ice sheets of 
Greenland and Antarctica, because they have great potential to 
change sea level. Snow falls on top, melting happens around the 
side, especially in Greenland, and our understanding of those 
processes has gotten a lot better. However, we have observed 
surprising changes in the flow of the ice sheets around their 
edges that we didn't really expect.
    If I may, for a moment, an ice sheet is just a two-mile-
thick, continent-wide pile of snow that has been squeezed to 
ice under its own weight. And like any pile, it spreads under 
its own weight. If I were to pour pancake batter on a griddle 
in front of us here, you would see it spread and thin and drip 
off the edge. The same thing happens to an ice sheet. It 
spreads and thins and it drips icebergs off of the edge.
    If I were to grease that pancake griddle, you would see the 
batter spread faster. Ice sheets have exactly the same problem. 
In Greenland, observations show that when the melt water starts 
on the edge, it goes through great holes in the ice to the 
bottom, and water makes things slippery. And so the ice 
actually spreads faster because of this melt water that 
amplifies the effects of it. And so in the same way that you 
can grease a pancake griddle, the ice sheet is greasing its own 
bed to spread faster.
    If I were holding the pancake batter in with a spatula and 
I removed it, of course, the batter would spread faster, and 
ice sheets have this same problem, as well. When the ice gets 
down to the ocean, it usually does not immediately break off to 
make an iceberg. It spreads over the ocean in something we call 
an ice shelf, and that will run aground on an island, or it 
will sheer past the rocky sides of a fjord, and those hold back 
in the same way that your spatula holds back the spreading 
pancake batter.
    Now in a warming world, those are very low in elevation. 
They can be warmed easily. They are in contact with the ocean 
already. They are at the melting point underneath, and so they 
can melt very easily underneath. We have seen where warming has 
attacked these spatulas, these ice shelves, and when they have 
been pulled out of the way, the ice behind is gone faster by as 
much as eight-fold. So we know these things are out there, and 
we know that we don't have a really good scientific 
understanding of all of these aspects. And when we look to the 
future, we expect sea level to rise, as ocean water warms and 
expands, as the mountain glaciers melt, and with effects from 
changing snowfall and melting on the big ice sheets.
    And there is a greatly increased confidence in that. If you 
compare the projections of sea level rise that were just now 
made in the new Report to those that were made in the previous 
report, we have a better understanding of certain things. The 
numbers have looked slightly different. Had we treated 
uncertainties in exactly the same way, you would have had very 
similar projections. They have not changed much. But we have 
this additional uncertainty that we just don't know whether 
these changes in the spreading of that giant pile in Antarctica 
or that giant pile in Greenland will slow down, whether they 
will stay constant, whether they will speed up. It is just this 
big uncertainty that is sitting out there.
    We do not have any credible scientific models of which I 
personally am aware that would dump an ice sheet into the ocean 
over decades. However, it is possible that we will reach 
temperatures over decades that, if sustained, would lose an ice 
sheet over centuries to millennia. As someone who works for a 
land grant institution, which tries to provide useful advice to 
you, I am distressed that I cannot tell you more accurately 
what the future might hold. As someone who gets paid to do 
research, I am really excited. I am going to go home and have 
fun.
    So to summarize, we have much scientific confidence that 
warming-induced ice loss is now widespread in the climate 
system, that it is contributing to sea level rise and other 
changes. Improved understanding of many aspects of this is 
reflected in the new Report, and it is really wonderful, but 
there are unexpected changes in ice flow that have occurred for 
which we lack a scientific basis to provide accurate estimates.
    Thank you.
    [The prepared statement of Dr. Alley follows:]
                 Prepared Statement of Richard B. Alley

                            Changes in Ice:

                        The 2007 IPCC Assessment

Introduction

    My name is Richard Alley.\1\ I am Evan Pugh Professor of 
Geosciences and Associate of the Earth and Environmental Systems 
Institute at the Pennsylvania State University. I have authored over 
170 refereed scientific publications in the areas of ice and climate, 
which are ``highly cited'' according to a prominent indexing service, 
and I have given hundreds of presentations concerning my areas of 
expertise. My research interests focus especially on glaciers and ice 
sheets, their potential for causing major changes in sea level, and the 
climate records they contain. I have been a member of many national and 
international committees, including chairing the National Research 
Council's Panel on Abrupt Climate Change and serving on their Polar 
Research Board. I have contributed to the efforts of the 
Intergovernmental Panel on Climate Change (IPCC) in various ways, and 
serve as a Lead Author on Chapter 4 (the Cryosphere), and on the 
Technical Summary and the Summary for Policy-makers of Working Group I 
of the Fourth Assessment Report. A brief description of the IPCC 
process as it applies to this testimony is appended, for your 
information.
---------------------------------------------------------------------------
    \1\ Any opinions, findings, conclusions, or recommendations 
expressed in this publication are those of the author and do not 
necessarily reflect those of the Pennsylvania State University, the 
Intergovernmental Panel on Climate Change, or other organizations.
---------------------------------------------------------------------------

Changes in Ice

    The newly released report reaffirms the strong scientific evidence 
that human activities are changing the composition of the planet's 
atmosphere, and that this is warming the climate and affecting it in 
other ways. In particular, our chapter documents the increasingly 
strong evidence for widespread reductions in the Earth's ice, including 
snow, river and lake ice, sea ice, permafrost and seasonally frozen 
ground, mountain glaciers, and the great ice sheets of Greenland and 
Antarctica. Our chapter and others highlight the strong evidence for 
the dominant role of warming, which is primarily being caused by human 
activities, in this loss of ice.
    I will briefly summarize some of these many aspects, especially 
focusing my attention on the issue of ice-sheet shrinkage and its 
possible effect on sea-level rise. I will rely on the recent IPCC 
report, as well as other materials as needed.
    Snow cover has decreased in most regions, as shown by satellite 
data tied to limited surface observations. Snow melt is shifting 
earlier into the spring. Declines in April 1 snowpack have been 
measured in 75 percent of western North American sites monitored. 
Impacts of climate change on people will be covered in the WGII report, 
coming soon, but other sources express great concern about earlier 
snowmelt in the U.S. West, because the snow pack in many regions is a 
dominant source of summertime water. Trends in snow cover cannot be 
explained by changing precipitation (and indeed, in some very cold 
places snow depth has increased with increasing precipitation), but the 
overall shrinkage of snow cover can be explained by rising temperature.
    Freezing of rivers and lakes generally has been occurring later in 
the fall, with thawing earlier in the spring, giving longer intervals 
of open water. Coordinated data collection is scarce, however, and the 
data set not extensive.
    Arctic sea ice, formed by freezing of ocean water, has decreased in 
area and thickness. The change in the summer has been especially large, 
with ice lost from an area twice the size of Texas between 1979 and 
2005 (decreasing trend in ice area of seven percent per decade over 
that interval). Data sets from satellites, tied to observations from 
ships submarines, have been especially important in documenting these 
changes. Although shifts in circulation of the ocean and atmosphere may 
have contributed to the ice loss, greenhouse-gas warming is likely to 
have been important. (Any Antarctic sea-ice changes fall within natural 
variability; cooling associated with the ozone hole may be affecting 
Antarctic climate, a complex subject beyond the scope of these brief 
remarks.)
    Permanently frozen ground (permafrost) and seasonally frozen ground 
are not readily monitored globally. However, available reports point to 
overall warming and thawing of this ice in the ground, in response to 
rising air temperatures and changes in snow cover.
    Glaciers and ice caps occur primarily in mountainous areas, and 
near but distinct from the Greenland and Antarctic ice sheets. On 
average, the world's glaciers were not changing much around 1960 but 
have lost mass since, generally with faster mass loss more recently. 
Glacier melting contributed almost an inch to sea-level rise during 
1961-2003 (about 0.50 mm/year, and a faster rate of 0.88 mm/year during 
1993-2003). Glaciers experience numerous intriguing ice-flow processes 
(surges, kinematic waves, tidewater instabilities), allowing a single 
glacier over a short time to behave in ways that are not controlled by 
climate. Care is thus required when interpreting the behavior of a 
particular iconic glacier (and especially the coldest tropical 
glaciers). But, ice-flow processes and regional effects average out if 
enough glaciers are studied for a long enough time, allowing glaciers 
to be quite good indicators of climate change. Furthermore, for a 
typical mountain glacier, a small warming will increase the mass loss 
by melting roughly five times more than the increase in precipitation 
from the ability of the warmer air to hold more moisture. Thus, 
glaciers respond primarily to temperature changes during the summer 
melt season. Indeed, the observed shrinkage of glaciers, contributing 
to sea-level rise, has occurred despite a general increase in 
wintertime snowfall.

Ice-sheet Changes

    The large ice sheets of Greenland and Antarctica are of special 
interest, because they are so big and thus could affect sea level so 
much. Melting of all of the world's mountain glaciers and small ice 
caps might raise sea level by about one foot (0.3m), but melting of the 
great ice sheets would raise sea level by just over 200 feet (more than 
60m). We do not expect to see melting of most of that ice, but even a 
relatively small change in the ice sheets could matter to the world's 
coasts.
    A paper published in the journal Science last week (Rahmstorf et 
al., 2007) compared the projections made in the 2001 IPCC Third 
Assessment Report to changes that have occurred. The carbon dioxide in 
the atmosphere has followed expectations closely. Temperature has 
increased just slightly faster than projected, but well within the 
stated uncertainties. Sea level is following near the upper edge of the 
stated uncertainties, however, well above the central estimate. Changes 
in the ice sheets help explain this.
    The 2001 IPCC report noted large uncertainties, but presented a 
central estimate that the combined response of the ice sheets to 
warming would be net growth, lowering the sea-level rise from other 
sources averaged over the 21st century, with increase in snowfall on 
the ice sheets exceeding increase in melting and with little change in 
ice flow. Data collected recently show that the ice sheets very likely 
have been shrinking and contributing to sea level rise over 1993-2003 
and with even larger loss by 2005, as noted in the IPCC report and 
elsewhere (e.g., Alley et al., in press; Cazenave, 2006). Thickening in 
central Greenland from increased snowfall has been more than offset by 
increased melting in coastal regions. Many of the fast-moving ice 
streams that drain Greenland (see the Figure, below) and parts of 
Antarctica have accelerated, transferring mass to the ocean and further 
contributing to sea-level rise. The total contribution to sea-level 
rise from the ice sheets remains smaller than the contribution from 
mountain-glacier melting or from the expansion of ocean water as it 
warms. However, the existence of the ice-sheet contribution, its 
important ice-flow source, and the large potential sea-level rise from 
such mechanisms in the future motivate careful consideration.
    An ice-sheet is a two-mile-thick, continent-wide pile of snow that 
has been squeezed to ice. All piles tend to spread under their own 
weight, restrained by their own strength (which is why spilled coffee 
spreads on a table top but the stronger table beneath does not spread), 
by friction beneath (so pancake batter spreads faster on a greased 
griddle than on a dry waffle iron), or by ``buttressing'' from the 
sides (so a spatula will slow the spreading of the pancake batter). 
Observations at a site in Greenland have shown that meltwater on top of 
the ice sheet flows through the ice to the bottom and reduces friction 
there. More melting in the future thus may reduce friction further, 
speeding the production of icebergs and the increase in sea level.
    Some early gothic cathedrals suffered from the ``spreading-pile'' 
problem, the sides tending to bulge out while the roof sagged down, 
with potentially unpleasant consequences. The beautiful solution was 
the flying buttress, which transfers some of the spreading tendency to 
the strong Earth beyond the cathedral. Ice sheets also have flying 
buttresses, called ice shelves. The ice reaching the ocean usually does 
not immediately break off to form icebergs, but remains attached to the 
ice sheet while spreading over the ocean. The friction of these ice 
shelves with islands, or with the sides of embayments, helps restrain 
the spreading of the ice sheet much as a flying buttress supports a 
cathedral. The ice shelves are at the melting point where they contact 
water below, and are relatively low in elevation hence warm above. Ice 
shelves thus are much more easily affected by climatic warming than are 
the thick, cold central regions of ice sheets. Rapid melting or 
collapse of several ice shelves has occurred recently, allowing the 
``gothic cathedrals'' behind to spread faster, contributing to sea-
level rise.
    Although science has succeeded in generating useful understanding 
and models of numerous aspects of the climate, similar success is not 
yet available for ice-sheet projections, for reasons that I would be 
happy to explore with the Committee. We do not expect ice sheets to 
collapse so rapidly that they could raise sea level by meters over 
decades; simple arguments point to at least centuries. However, the 
IPCC report is quite clear on the lack of scientific knowledge to make 
confident projections.

Synopsis

    In summary, with high scientific confidence, changes are occurring 
in much of the world's ice. These are being caused primarily by 
warming. That warming is largely being caused by greenhouse gases being 
released to the atmosphere by human activities. Shrinkage of the large 
ice sheets was unexpected to many observers but appears to be 
occurring, and the poor understanding of these changes prevents 
reliable projections of future sea-level rise over long times.



Recently published estimates of the mass balance of the Greenland ice 
                    sheet through time (Alley et al., in press)

    A Total Mass Balance of 0 indicates neither growth nor shrinkage, 
and -180 Gt yr-1 indicates ice-sheet shrinkage contributing to sea-
level rise of 0.5 mm/year (one inch in about 50 years), as indicated. 
Each box extends from the beginning to the end of the time interval 
covered by the estimate, with the upper and lower lines indicating the 
uncertainties in the estimates. A given color is associated with a 
particular technique, and the different letters identify different 
studies. Two estimates have arrows attached, because those authors 
indicated that the change is probably larger than shown. The dotted box 
in the upper right is a frequently-cited study that applies only to the 
central part of the ice sheet, which is thickening, and misses the 
faster thinning in the margins.

References Cited

Alley, R.B., M.K. Spencer and S. Anandakrishnan. Ice-sheet mass 
        balance: Assessment, attribution and prognosis. In press. 
        Annals of Glaciology.
Cazenave, A. 2006. How fast are the ice sheets melting? Science 314, 
        1250-1252.
Rahmstorf, S., A. Cazenave, J.A. Church, J.E. Hansen, R.F. Keeling, 
        D.E. Parker and R.C.J. Somerville. 2007. Recent observations 
        compared to projections. Science, Sciencexpress, 10.1126/
        science.1136843.

The Intergovernmental Panel on Climate Change (IPCC) Assessment

    The IPCC was founded by the United Nations Environment Programme 
and the World Meteorological Organization in 1988 (this information is 
summarized from the publications of the IPCC, which are widely 
available including at www.ipcc.ch). The Panel is charged to assess the 
best scientific information on climate change, in a comprehensive, 
objective, open and transparent way. The panel is divided into three 
working groups. Working Group I assesses the scientific aspects of the 
climate system and climate change. Working Group II assesses the 
vulnerability of socio-economic and natural systems to climate change, 
negative and positive consequences of climate change, and options for 
adapting to it. Working Group III assesses options for limiting 
greenhouse gas emissions and otherwise mitigating climate change.
    The IPCC reports are written by teams of authors, who are nominated 
by governments and international organizations. Author selection is 
based on expertise relative to the specific task. Experts come from 
universities, research centers, business and environmental 
associations, and other organizations from more than 130 countries. 
Procedures are enforced to ensure that the results of the IPCC process 
are policy-relevant. A rigorous review process is used throughout the 
process. Specialists review a first draft of the report, and 
governments, authors and independent experts review a second draft, 
with special review editors for each chapter ensuring that balance is 
maintained and that all review comments are properly addressed. For our 
chapter, Chapter 4 (the Cryosphere) of Working Group I of the Fourth 
Assessment Report, which in near-final draft had 47 pages, 255 
references, and 23 figures involving 41 panels, the two Coordinating 
Lead Authors, nine Lead Authors (informed by 44 contributing authors), 
and two review editors addressed over 1,000 comments from the expert 
review alone. As one of the shorter chapters, we were not the busiest. 
The Third Assessment Report in total involves more than 2,500 expert 
reviewers, 800 contributing authors, and 450 Lead Authors.
    The report from Working Group I was condensed into a Technical 
Summary, and then into a Summary for Policy-makers. The Summary for 
Policy-makers was approved line-by-line by governments in plenary from 
January 29 to February 1 in Paris, and was released to the public on 
February 2, 2007. The Technical Summary and the full report will follow 
later in the spring, as will reports from Working Groups II and III. 
The approximately 1,000-page main report from Working Group I is being 
copy-edited and formatted for publication, with a limited number of 
small changes in specific wording for clarity based on the results of 
the Paris plenary.

                     Biography for Richard B. Alley
    Dr. Richard Alley is Evan Pugh Professor of Geosciences and 
Associate of the Earth and Environmental Systems Institute at The 
Pennsylvania State University, University Park, where he has worked 
since 1988. He was graduated with the Ph.D. in 1987 from the University 
of Wisconsin-Madison and with M.Sc. (1983) and B.Sc. (1980) degrees 
from The Ohio State University-Columbus, all in Geology. Dr. Alley 
teaches, and conducts research on the climatic records, flow behavior, 
and sedimentary deposits of large ice sheets, to aid in prediction of 
future changes in climate and sea level. His experience includes three 
field seasons in Antarctica, eight in Greenland, and three in Alaska. 
His awards include the Seligman Crystal of the International 
Glaciological Society, the first Agassiz Medal of the European 
Geosciences Union Cryospheric Section, a Presidential Young 
Investigator Award, the Horton Award of the American Geophysical Union 
Hydrology Section and Fellowship in the Union, the Wilson Teaching 
Award and the Mitchell Innovative Teaching Award of the College of 
Earth and Mineral Sciences and the Faculty Scholar Medal in Science at 
Penn State. Dr. Alley has served on a variety of advisory panels and 
steering committees, including chairing the National Research Council's 
Panel on Abrupt Climate Change, and has provided requested advice to 
numerous government officials in multiple administrations including a 
U.S. Vice President, the President's Science Advisor, and a Senate 
Committee. He has published over 170 refereed papers, and is a ``highly 
cited'' scientist as indexed by ISI. His popular account of climate 
change and ice cores, The Two-Mile Time Machine, was chosen science 
book of the year by Phi Beta Kappa in 2001. Dr. Alley is happily 
married with two children, two cats, and two bicycles, and resides in 
State College, PA, where he coaches recreational soccer and 
occasionally plays some.

    Chairman Gordon. Thank you, Dr. Alley.
    I just received a message here that the International House 
of Pancakes wanted to offer you an evening job if you need to 
supplement. I know that land grant institutions don't pay that 
well.
    Dr. Meehl.

  STATEMENT OF DR. GERALD A. MEEHL, COORDINATING LEAD AUTHOR, 
IPCC, WORKING GROUP I, CHAPTER 10: GLOBAL CLIMATE PROJECTIONS; 
   SENIOR SCIENTIST, NATIONAL CENTER FOR ATMOSPHERIC RESEARCH

    Dr. Meehl. Yes. Dr. Alley's enthusiasm is, indeed, 
contagious. I think we would all like to run back to our labs 
and get back to work on science after doing a lot of this kind 
of assessment work.
    But I want to thank the Chairman and Members of the 
Committee for the opportunity to communicate to you some of the 
findings from the IPCC AR4.
    The thing I wanted to stress, the first thing, is that a 
significant new aspect regarding projections of future climate 
change has involved an unprecedented coordinated international 
effort to perform a set of climate change experiments. These 
were done with high-end computer climate modeling tools we use 
to quantify possible future climate change. These are called 
Global-Coupled Ocean and Atmosphere Climate Models, or we just 
call them AOGCMs for short, and a total of 16 modeling groups 
from around the world from 11 countries, and this includes 
three groups in the United States, use 23 of these high-end 
models, AOGCMs, to perform coordinated climate-change 
experiments. These include simulations of 20th century climate 
with both natural and anthropogenic forcings, three possible 
outcomes for the 21st century based on low, medium, and high 
emission scenarios and three idealized stabilization 
experiments.
    These data were then collected and made openly available 
for analysis, and this is really the first time we have been 
able to do something on this scale. And to date, over 950 
scientists from around the world have accessed these model 
data. And the many papers that have been written were assessed 
by us in the process of coming up with the AR4. These analyses 
provide an improved quantification of likelihoods and many 
aspects of future climate change.
    And a little more on the models, the amount of detail and 
realism in the climate models we use has increased in recent 
years. This is partly because of our increase in understanding 
of the processes in the climate system and also in part because 
the calculations provided by newer supercomputers has 
increased.
    For future climate, this now allows us to provide more 
detailed information on aspects of the climate system, such as 
possible future changes of weather and climate extremes.
    Regarding near-term climate change, warming of about two-
tenths of a degree centigrade per decade over the next couple 
of decades is projected across the range of scenarios 
considered. And this actually continues about the same rate we 
have observed in observations over the past few decades.
    Hypothetically, if concentrations of greenhouse gases had 
been held constant at year 2000 values, we are already 
committed to about a tenth of a degree C per decade, mainly due 
to the slow response of the ocean. By the 2020s, most of the 
United States is projected to warm by about an additional one 
degree centigrade, and this is larger than warming we observed 
during the 20th century and very likely larger than estimates 
of natural variability during the 20th century.
    As we approach the middle part of the 21st century and 
beyond, it is clear that it makes a difference regarding what 
emission scenario we choose to follow now. By 2100, there is a 
spread of globally-averaged surface air temperature increase 
among the six scenarios considered. Best estimates for this 
global warming range from about 1.8 degrees centigrade for the 
lowest scenario with a likely range of 1.1 to 2.9 degrees C and 
four degrees C for the highest scenario with a likely range of 
2.4 degrees to 6.4 degrees centigrade.
    Now these scenarios are constructed based on various 
assumptions of future population growth, economic activity, and 
energy usage, but no climate initiatives were considered in 
these scenarios.
    So based on the existing models available for assessment, 
the central values for projection of sea level rise by 2100 are 
similar to previous estimates. These range from about 20 to 40 
centimeters, depending on scenario, with the upper end of the 
range for the highest scenario of about 60 centimeters. These 
ranges of sea level rise are narrower than previous estimates, 
mainly because of reduced uncertainties in some of the 
components that contribute to sea level rise.
    However, a large unquantified uncertainty arises from 
processes we don't yet fully understand and have only recently 
been able to observe, such as potential ice sheet instability 
that Dr. Alley was alluding to.
    For example, additional sea level rise from this source by 
the end of the 21st century could add another 10 to 20 
centimeters to the upper ranges and higher future sea level 
rise values cannot be excluded. This is an area of great 
concern and active ongoing research given the potential 
consequences.
    As seen in recent trends and observations, the future 
pattern for temperature change is characterized by greater 
warming over land compared to oceans and more warming at high 
northern latitudes. Associated with these temperature changes 
there are projected decreases of snow cover, decreases in thaw 
depth over most permafrost regions and other changes. 
Reductions in sea ice, of course, go along with increased 
temperatures with a late summer sea ice free Arctic by the end 
of the 21st century in the high forcing scenario in some 
models. The pattern of future precipitation change indicates 
increases at higher latitudes, such as the northern tier of 
states during winter and decreases over subtropical land areas, 
such as the Southwest United States.
    Though the picture of a future warming world appears bleak, 
it is not yet hopeless. The six different mission scenarios 
considered in the AR4 show that the longer we wait to do 
something, the worse the problem gets. These scenarios also 
illustrate that what we do now can make a difference for the 
future.
    Thank you very much for your invitation to address the 
Committee.
    [The prepared statement of Dr. Meehl follows:]
                 Prepared Statement of Gerald A. Meehl

                      Global Climate Projections:

                        The 2007 IPCC Assessment

Introduction

    I thank the Chairman and other Members of the Committee for the 
opportunity to communicate to you today some of the recent findings 
from the IPCC Fourth Assessment Report (AR4). My name is Gerald Meehl, 
Senior Scientist at the National Center for Atmospheric Research (NCAR) 
in Boulder, Colorado. My research interests include tropical climate 
involving the monsoons and El Nino Southern Oscillation, climate 
variability and climate change. I have authored or co-authored more 
than 145 peer-reviewed scientific journal articles and book chapters. I 
have been involved with the Intergovernmental Panel on Climate Change 
(IPCC) assessments since the first one that was published in 1990. I 
was a Contributing Author on that first assessment and its update in 
1992, a Lead Author for the 1995 Assessment, and a Coordinating Lead 
Author for the 2001 and the present 2007 assessments. I have been 
involved with committees of the World Climate Research Program (WCRP) 
on Climate Variability and Predictability (CLIVAR), and am currently 
Co-Chair of the WCRP/CLIVAR Working Group on Coupled Models (WGCM). 
This committee organized and coordinated the international modeling 
groups in performing climate model experiments for assessment in the 
AR4, and in the collection and analysis of data from those model 
experiments. Through the efforts of that committee, this extensive 
multi-model data set on climate change has been made openly available 
for analysis, and over 950 scientists from around the world have been 
able to access and analyze these data. The resulting papers have 
contributed extensively to the IPCC AR4. I have served on several 
National Research Council (NRC) panels, and am currently a member of 
the NRC Climate Research Committee. I was a Lead Author on the U.S. 
Climate Change Science Program (CCSP) Report 1.1 on temperature trends 
in the atmosphere, and am currently co-coordinator for the CCSP report 
on weather and climate extremes in a changing climate.
    In my capacity as a Coordinating Lead Author for the chapter on 
climate change projections for the IPCC AR4, I was in Paris last week 
attending the Plenary of the IPCC where the IPCC Fourth Assessment 
Report was accepted and approved by the roughly 180 governments that 
make up the IPCC. Thus, the IPCC is a group of governments, not a group 
of scientists, which is a common misconception. The IPCC commissions 
assessments to be performed roughly every five or six years, and they 
are prepared through the efforts of hundreds of scientists from around 
the world who are actively involved in state-of-the-art research in 
climate science. The IPCC assessments provide a comprehensive view of 
the current state of human understanding of climate science and climate 
change. My testimony today will summarize some of the main findings of 
the IPCC AR4 with regards to projections of future climate change.

A much larger group of climate models have contributed to the IPCC AR4

    A major international effort to perform a set of coordinated 
climate change experiments was organized by the WCRP/CLIVAR WGCM. A 
total of 16 modeling groups from 11 countries (three groups from the 
U.S.) used 23 global coupled climate models to perform these 
coordinated climate change experiments that involved simulations of the 
20th century climate, three possible outcomes for the 21st century 
(based on low, medium and high emission scenarios), and three idealized 
stabilization experiments. In addition there were idealized carbon 
dioxide increase experiments, and associated stabilization experiments 
with doubled and quadrupled CO2 amounts. These data were 
then collected, and over 31 Terabytes of model data were archived at 
the DOE-sponsored Program for Climate Model Diagnosis and 
Intercomparison (PCMDI) at Lawrence Livermore National Lab (LLNL) in 
Livermore, CA. WGCM then coordinated the analysis of this multi-model 
data set. This unprecedented effort has involved over 950 scientists 
who have accessed these model data and wrote many papers that were 
assessed in the AR4. This massive effort was the first time the 
international climate modeling community has performed such an 
extensive set of climate change experiments, with the output from those 
experiments openly available for analysis.

Climate change commitment and near-term warming

    Several of the experiments run with the most recent global climate 
models explored the concept of climate change commitment. That is, if 
concentrations of greenhouse gases are stabilized at various levels, 
how much more warming would occur due to the emissions already in the 
system. Such committed climate change is due to the time lag introduced 
by the oceans because it takes longer for water to warm. If 
concentrations of greenhouse gases could have been stabilized in the 
year 2000, a committed warming of about 0.1C per decade averaged over 
the period 2000 to 2020 would occur, with smaller warming continuing 
after that. Of course there are ongoing increases of greenhouse gases, 
so the models project that no matter what emissions scenario is 
followed (not taking into account possible large volcanic eruptions 
that we are not able to forecast but would produce temporary cooling a 
year or two after the eruption), the combination of climate change 
commitment and additional warming from increasing greenhouse gases 
would result in a warming of about 0.2C per decade over the next two 
decades.
    The sea level rise commitment is much longer-term. This is due to 
the effects of thermal expansion on sea level. That is, since water has 
the physical property of expanding as it heats up, as the warming 
penetrates deeper into the ocean, an ever increasing volume of water 
expands and contributes to ongoing sea level rise. Since it would take 
centuries for the entire volume of the ocean to warm in response to the 
effects of the greenhouse gases we have already put into the air, we 
are committed right now to further sea level rise that would continue 
for centuries.
    Previous IPCC assessments starting in 1990 used global climate 
models to project global warming of between about 0.15C and 0.3C per 
decade for 1990 to 2005. The actual observed values of global warming 
for that time period are about 0.2C per decade. This increases our 
confidence in the climate model projections for future climate change, 
since previous generations of models were able to project warming rates 
similar to those subsequently observed.

Climate change later in the 21st century

    As we approach the middle part of the 21st century and beyond, it 
makes a difference regarding what emissions scenario we choose to 
follow now. By 2100 there is a spread of globally averaged surface air 
temperature increase among the six scenarios considered, with best 
estimates ranging from nearly 2C for a lowest scenario (B1) and about 
4C for the highest scenario (A1FI). Likely ranges for warming at the 
end of the 21st century are also now provided. For example, for a low 
scenario (B1), the warming averaged for 2090-99 relative to 1980-99 has 
a best estimate of 1.8C with a likely range of 1.1C to 2.9C. For a 
medium scenario (A1B), the best estimate is 3.4C with a likely range of 
2.0C to 5.4C, and for the highest scenario (A1FI), the best estimate is 
4.0C with a likely range from 2.4C to 6.4C. There are greater values at 
the higher end of the ranges due to relatively new understanding 
regarding the nature of the feedbacks from the carbon cycle (i.e., how 
the oceans and land absorb and emit carbon dioxide). Though only 
relatively few global coupled climate models include the complex 
processes involved with modeling the carbon cycle, this feedback is 
positive (i.e., adding to more warming) in all models so far 
considered. Therefore, the addition of carbon cycle feedbacks provides 
higher values on the warm end of the uncertainty ranges.
    Rising global temperatures are very likely to raise sea level by 
expanding ocean water and melting mountain ice caps and glaciers. 
Recently observed ice sheet dynamical processes that could produce 
potentially larger contributions to sea level rise than accounted for 
in the present estimates are not fully included in existing models of 
the Greenland and Antarctic ice sheets assessed for the AR4. Therefore 
larger increases in sea level rise than the present projections cannot 
be excluded. Consequently, the AR4 cannot quantify a full uncertainty 
range of sea level rise at the end of the 21st century. Based on the 
existing models available for assessment, the central values for 
projections of sea level rise by 2100 are similar to previous 
estimates, ranging from about 30 to 40 cm. About 60 percent to 70 
percent of this increase is due to thermal expansion of sea water 
(i.e., as water warms, it expands) and is thus connected to the more 
certain estimates of warming of surface air temperatures. There is less 
certainty with regards to the other components of sea level rise 
(contributions from melting land glaciers and small ice caps, the net 
balance between snow accumulation and melting ice for Greenland and 
Antarctica, and the dynamic ice flow contributions from Greenland and 
Antarctica). This is reflected in the ranges of sea level rise that 
differ from previous estimates, due in part to the way the uncertainty 
of these contributions is taken into account. This is an area of great 
concern and active ongoing research given the potential consequences.
    The projected globally averaged temperature increase is also 
reflected by patterns of regional climate changes. As noted in previous 
assessments, this pattern for temperature change is characterized by 
greater warming over land compared to oceans, and more warming at the 
high northern latitudes. Associated with these temperature changes, 
there are projected decreases of snow cover, and increases in thaw 
depth over most permafrost regions. Reductions in sea ice go along with 
the increased temperatures, with a sea-ice free Arctic by the end of 
the 21st century in the high forcing scenario in some models. The 
pattern of future precipitation change indicates likely increases at 
higher latitudes, such as the northern tier of states, and decreases 
over subtropical land areas such as the Southwest U.S.
    It would seem that the relatively small increases in average 
temperature amounting to a few degrees may not make that much 
difference. However, such small changes in average values can lead to 
much larger changes of extreme weather and climate events. For example, 
it is very likely that heat waves will increase in intensity, frequency 
and duration, with heavy precipitation events also increasing. These 
projected changes in extremes continue trends we have already observed.
    Though present-day global climate models used for the climate 
change projections discussed above have inherent limitations in 
simulating hurricanes, new types of specialized models have been 
formulated to study such possible future changes. From a range of 
models, it is likely that future tropical cyclones (typhoons and 
hurricanes) will become more intense with larger peak wind speeds and 
more intense precipitation. This is physically consistent with ongoing 
increases of sea surface temperature since there is a well-established 
link between warmer water and hurricane intensity. There is less 
confidence in projections of a global decrease in numbers of hurricanes 
since the model results are not as consistent.
    There has been some interest in the media and in Hollywood 
regarding the possibility of an abrupt shutdown of the Atlantic Ocean 
meridional overturning circulation (MOC). This large-scale ocean 
circulation system, sometimes called the ``ocean conveyor belt,'' 
transports heat northwards, in part via the Gulf Stream, to the North 
Atlantic. A warming of the North Atlantic from increasing greenhouse 
gases could produce more precipitation and warmer water that would 
stabilize this overturning circulation and consequently reduce the 
amount of northward heat transport. Using this line of reasoning, if 
the MOC suddenly shut down, there could be a sudden decrease in 
northward heat transport and possibly a large cooling of the North 
Atlantic region. Research assessed in the IPCC AR4 indicates that it is 
very likely that the MOC will indeed slow down during the 21st century. 
With the weakening of this circulation, there is somewhat less heat 
transported northward. But there is still a future net increase of 
surface air temperatures over the North Atlantic since the warming from 
the increased greenhouse gases overwhelms any cooling from the MOC 
slowdown. Additionally, it is very unlikely that the MOC will undergo a 
large abrupt shut-down during the 21st century, with an associated 
cooling from such a sudden shut-down also very unlikely. No global 
coupled climate model simulation assessed in the AR4 produces such an 
abrupt change, even if Greenland ice melt is taken into account. 
However, changes in the MOC in the 22nd century and beyond cannot be 
assessed with confidence at this time.

Summary

    The IPCC AR4 represents the current state of human understanding of 
climate science and climate change. Projected changes of future climate 
have relied on an unprecedented set of coordinated climate change 
experiments undertaken by the international climate modeling community, 
and the U.S. modeling groups have played a prominent role in this 
process. The projections of future climate are consistent with earlier 
IPCC assessments in terms of the magnitude of global changes. This is 
reassuring since successive generations of climate models are now 
producing comparable results from assessment to assessment. But there 
are now many more details as well as increased certainty regarding 
quantifications of regional climate change, extremes, hurricanes, 
climate change commitment, ocean circulation changes, and better 
information regarding both near-term and longer-term climate change.

                     Biography for Gerald A. Meehl
    Gerald Meehl received his Bachelor's (1974), Master's (1978), and 
Ph.D. (1987) degrees in climate dynamics from the University of 
Colorado in Boulder. Since 1973, he has worked at the National Center 
for Atmospheric Research (NCAR) in various capacities, including 
participating in the Tropical Wind Energetics Reference Level 
Experiment (TWERLE) in Pago Pago, American Samoa, and Christchurch, New 
Zealand (1975-76), in the Monsoon Experiment (MONEX) in Bintulu, 
Sarawak, Malaysia, and Kathmandu, Nepal (1978-79), and in the Tropical 
Ocean Global Atmosphere (TOGA) Coupled Ocean Atmosphere Response 
Experiment (COARE) in Townsville, Australia, Kapingamarangi, FSM, 
Pohnpei, FSM, and Republic of Nauru (1992-93). Since 1979, as a 
scientist in the Climate and Global Dynamics Division, he has studied 
the interactions between El Nino/Southern Oscillation (ENSO) and the 
Indian monsoon, analyzed the results from global coupled ocean-
atmosphere general circulation models at NCAR, and examined the 
possible effects of increased carbon dioxide, sulfate aerosols, and 
other forcings on global climate. He is the author of more than 140 
scientific papers in peer-reviewed journals, and has contributed 
chapters to several textbooks. He was a contributing author for the 
Intergovernmental Panel on Climate Change (IPCC) 1990 and 1992 
assessments, a Lead Author for the chapter on climate model projections 
of future climate change for the 1995 IPCC assessment, a Coordinating 
Lead Author for the chapter on climate model projections of future 
climate change for the IPCC Third Assessment Report published in 2001, 
and a Coordinating Lead Author for the chapter on global climate change 
projections for the 2007 IPCC Fourth Assessment Report. Among his 
current committee appointments, he is a member of National Research 
Council Climate Research Committee, Co-Chair of the Community Climate 
System Model Climate Change Working Group, Co-Chair of the World 
Climate Research Programme CLIVAR Working Group on Coupled Models 
(WGCM), and Chairman of the WGCM Climate Simulation Panel which has 
coordinated analyses of global coupled climate model simulations for 
the IPCC Fourth Assessment Report.

                               Discussion

                            The IPCC Process

    Chairman Gordon. Thank you, Dr. Meehl.
    Now, Dr. Solomon, the message I am taking away from this 
Report is that the climate is changing, the Earth is getting 
warmer, human activities have started and continue to drive 
this change. Have I gotten that message right?
    Dr. Solomon. Basically, yes. I would put some ``very 
likely''s in there, but I would agree with you.
    Chairman Gordon. Thank you. And Dr. Solomon, I understand 
that all 113 nations had to agree on that. This had to be a 
unanimous Report, is that correct?
    Dr. Solomon. All of the nations present in Paris, including 
the United States, were in agreement with the final document. 
That is correct. It was a consensus document.
    Chairman Gordon. And by virtue of that, does that mean that 
this would be on the conservative side of a report?
    Dr. Solomon. I would actually say that the point of this 
kind of a report is to say what we know, what we don't know, 
and what the remaining uncertainties are. I don't think that a 
report, such as ours, if it is intended to be the sort of 
global consensus statement that it is could go any farther than 
we have gone. I think we have done a very fair job in reporting 
what is known and what is not known. I would not call it 
conservative, personally.

                       Glacier Melt Accelerations

    Chairman Gordon. And Dr. Alley, I understand that the 
research had to be cut off by the end of 2005, and so 
additional information that came from Greenland with the ice 
floats and things of this nature were not a part of this 
information. Is that correct?
    Dr. Alley. Some of the information on acceleration in 
Greenland did come in time to be assessed properly and a couple 
of recent papers are not included. That is correct.
    Chairman Gordon. And from press reports that I have seen, 
it indicated that in terms of the rise in sea level, you were 
somewhat limited to the change of temperature. As the water got 
warmer, obviously, it would expand. How limited were you in the 
discussions and the new information concerning Greenland and 
elsewhere where glaciers were melting?
    Dr. Alley. The melting of mountain glaciers, in the Alps, 
for example, or in the Rockies, is taken account of, and--with 
improved accuracy, so I think we understand better. The changes 
in snowfall and melting on top of Greenland and on top of 
Antarctica are also taken into account and somewhat better than 
it had been. The----
    Chairman Gordon. But was it taken into account in terms of 
the rise in the sea level?
    Dr. Alley. It is taken into account in terms of rise in sea 
level. What is missing is an accurate assessment of these 
changes in the spreading, the changes in the flow, how much the 
self-lubrication of the ice or the loss of the spatulas would 
contribute to accelerated flow in a warmer world. And we simply 
don't have the scientific understanding to provide an accurate 
assessment of that.
    Chairman Gordon. But we know it is not going to get slower. 
It is only going to get faster. The question is just how much 
faster.
    Dr. Alley. But we don't even really know that, because that 
sort of implies a knowledge that we are trying rather 
desperately to build for you right now. Certainly, we have seen 
glacier accelerations, and we have seen those accelerations in 
response to warming. We have fairly high confidence in that. If 
you see future warming, it, perhaps, would not be surprising 
that if warming causes mass loss that more warming would cause 
more mass loss, but we are still fighting on that. This 
document works very, very hard to be an assessment of what is 
known scientifically, what is well founded in the refereed 
literature, and when we come up to that cliff and look over and 
say we don't have a foundation right now, we have to tell you 
that. And on this particular issue, the trend of acceleration 
of this flow with warming, we don't have a good assessed 
scientific foundation right now.
    Chairman Gordon. How long would you expect that that would 
be before you will?
    Dr. Alley. I don't know. I am very optimistic that we will 
be better in five years. I am doubtful that we will have as 
good an understanding of that as we do of, say, mean global 
surface temperature that Dr. Meehl was talking about.
    Chairman Gordon. Thank you, Dr. Alley.
    Mr. Rohrabacher.
    Mr. Rohrabacher. Thank you very much, and thank you very 
much, Dr. Alley, for your honesty and your candor, considering 
that people obviously wanted you to say something else than 
what you have just told us, that they would like to have 
certainty. For the record, Mr. Chairman, I would like to put in 
the record a list of a number of scientists and statements by 
scientists, very well respected statements and very well 
respected scientists, who are not part of this so-called 
consensus that any climate change is being caused by human 
activity. If I could submit those for the record at this point.
    Chairman Gordon. Certainly, Mr. Rohrabacher, and I will 
also point out that the Minority had the opportunity to call 
any of these witnesses and have them be part of this panel----
    Mr. Rohrabacher. I appreciate that----
    Chairman Gordon.--and had quite a bit of time to be able to 
do that. But certainly this will add to our report. And without 
any objection, they will be made a part of the record.
    [The information follows:]
Information to be placed in the record relating to the House Science & 
  Technology Committee hearing on The State of Climate Change Science 
        2007 on February 8, 2007 by Congressman Dana Rohrabacher
Timothy Ball
    ``Believe it or not, Global Warming is not due to human 
contribution of Carbon Dioxide (CO2). This in fact is the 
greatest deception in the history of science. We are wasting time, 
energy and trillions of dollars while creating unnecessary fear and 
consternation over an issue with no scientific justification.''

    Monday, February 5, 2007
    Open News web site

http://www.opednews.com/articles/
opedne-daniel-g-070207-globa
l-warming- 3a-the-.htm

    Dr. Tim Ball, Chairman of the Natural Resources Stewardship Project 
(www.nrsp.com), is a Victoria-based environmental consultant and former 
climatology Professor at the University of Winnipeg. He can be reached 
at: [email protected]

Fred Singer
    ``Crucially, greenhouse models cannot explain the observed patterns 
of warming--temperature trends at different latitudes and altitudes. 
These data, published in a U.S. Government scientific report in May 
2006, lead us to conclude that the human contribution is not 
significant. Most of current warming must therefore stem from natural 
causes. It may well be part of an unstoppable solar-driven 1,500-year 
cycle of warming and cooling that's been documented in ice cores, ocean 
sediments, stalagmites, and so forth--going back a million years.
    ``If indeed most of current warming is natural rather than from 
greenhouse gases, there is little point in reducing carbon dioxide 
emissions. Further, carbon dioxide is not an atmospheric pollutant. 
Programs and policies for carbon dioxide control should therefore be 
scrapped--including uneconomic alternative energy sources, carbon-
sequestration efforts, and costly emission-trading schemes. All of 
these waste money and squander scarce resources, without in any way 
affecting the atmosphere or climate. Humans have adapted to major 
climate changes in the past, and we should have no problem doing so in 
the future.''

    The Science and Environmental Policy Project's The Week That Was 
newsletter (2/3/07)

http://www.sepp.org/Archive/weekwas/2007/February%203.htm

    S. Fred Singer, an atmospheric physicist, is Professor Emeritus of 
environmental sciences at the University of Virginia, adjunct scholar 
at the National Center for Policy Analysis, and former Director of the 
U.S. Weather Satellite Service. He is also a research fellow at the 
Independent Institute and author of Hot Talk, Cold Science: Global 
Warming's Unfinished Debate (The Independent Institute, 1997).

Bill Gray
    ``I think we're coming out of the little ice age, and warming is 
due to changes to ocean circulation patterns due to salinity 
variations.''

    Quote from an article in the Daily Reporter-Herald (9/19/06)

    Dr. William M. Gray is a world famous hurricane expert and Emeritus 
Professor of Atmospheric Science, Colorado State University.

    From an interview with Dr. William M. Gray in Discover Magazine, 
September 2005, Title: ``Weather Seer: `We're Lucky' ''

A few years ago, you almost called it quits because you'd lost so much 
funding. What made you continue?

G: I don't have the budget that I had, so I have to cut back my project 
way back. I am in retirement. I'm still working everyday, but I don't 
teach and don't have as many graduate students and as much financial 
need. I've got a little money from Lexington Insurance out of Boston, 
and I have some National Science Foundation money. For years haven't 
had any NOAA, NASA, or Navy money. But I'm having more fun. Right now 
I'm trying to work on this human-induced global warming thing that I 
think is grossly exaggerated.

You don't believe global warming is causing climate change?

G: No. If it is, it is causing such a small part that is negligible. 
I'm not disputing that there has been global warming. There was a lot 
of global warming in the 1930's and '40s, and then there was a slight 
global cooling from the middle '40s to the early '70s. And there has 
been warming since the middle '70s, especially in the last 10 years. 
But this is natural, due to ocean circulation changes and other 
factors. It is not human induced.

That must be a controversial position among hurricane researchers.

G: Nearly all of my colleagues who have been around 40 or 50 years are 
skeptical as hell about this whole global warming thing. But no one 
asks us. If you don't know anything about how the atmosphere functions, 
you will of course say, ``Look, greenhouse gases are going up, the 
globe is warming, they must be related.'' Well, just because there are 
two associations, changing with the same sign, doesn't mean that one is 
causing the other.

With last year's hurricane season so active, and this year's looking 
like it will be, won't people say it's evidence of global warming?

G: The Atlantic has had more of these storms in the least 10 years or 
so, but in other ocean basins, activity is slightly down. Why would 
that be so if this is climate change? The Atlantic is a special basin? 
The number of major storms in the Atlantic also went way down from the 
middle 1960s to the middle '90s, when greenhouse gases were going up.

Why is there scientific support for the idea?

G: So many people have a vested interest in this global warming thing. 
. .all these big labs and research and stuff. The idea is to frighten 
the public, to get money to study it more. Now that the cold war is 
over, we have to generate a common enemy to support science, and what 
better common enemy for the glove than greenhouse gases?

Are your funding problems due in part to your views?

G: I can't be sure, but I think that's a lot of the reason. I have been 
around 50 years, so my views on this are well known. I had NOAA money 
for 30 some years, and then when the Clinton Administration came in and 
Gore started directing some of the environmental stuff, I was cut off. 
I couldn't get any NOAA money. They turned down 13 straight proposals 
from me.

                         Global Warming Trends

    Mr. Rohrabacher. Thank you.
    My question--well, first of all, Dr. Solomon, is a glacier 
named after you?
    Dr. Solomon. Yeah, I am afraid so.
    Mr. Rohrabacher. Is it melting? I am serious about that. Is 
the glacier named after you melting?
    Dr. Solomon. Well, that particular one is at 78 degrees 
south, sir. It is at such a high latitude in the Antarctic 
that----
    Mr. Rohrabacher. So it is not melting?
    Dr. Solomon.--it is out of reach of global warming.
    Mr. Rohrabacher. It is out--it is not melting. Thank you 
very much.
    Let me--I am not a scientist. Look, I am a former 
journalist and a writer, and so I have to really, you know, 
look down and see what is being said, condense things into the 
real meaning. Let me ask you just a couple fundamental 
questions.
    I saw on the History Channel a whole big special on the 
mini ice age. Was there a mini ice age, and did it end at about 
the middle of the 19th century? Or you know, were there really 
Vikings that were living at a much higher temperature on 
Greenland 1,000 years ago, or are we being--is the History 
Channel just telling us, you know, a myth?
    Dr. Trenberth. Mr. Rohrabacher, if I can have a crack at 
that. There was a period called the little ice age----
    Mr. Rohrabacher. Okay.
    Dr. Trenberth.--that, indeed, occurred around about that 
time up until about the end of, say, the 19th century, which 
was----
    Mr. Rohrabacher. All right.
    Dr. Trenberth.--clearly cooler. It is a little bit of a 
Eurocentric view of the world, though, because a lot of it was 
certainly focused in the North Atlantic European region where, 
you know----
    Mr. Rohrabacher. Well, that, of course, is where we had all 
of the statistics being kept, and so at that time period, of 
course it would be Eurocentric, because they didn't keep all of 
those temperature records in other places in the world. So 
there was a mini ice age, and it went down to about the middle 
of the 19th century. I couldn't help but notice that the chart 
that was presented started the low point of this mini ice age. 
It started there to prove that there was a global warming 
trend.
    Now if you start at the bottom of something that is 
recognized as a time of cooling on the Earth, isn't it going to 
go up naturally if there is a natural cycle going on?
    Dr. Trenberth. The instrumental record, we have been able 
to push it back to 1850, and that is the reason it starts then. 
And the way we would characterize it is that there is really 
not much change up until about 1920. There is a warming that 
goes on from about 1920 to 1940, and we believe that some of 
that--the work that the models have done and the instruments 
and what has happened with the sun is that a part of that is 
natural and associated with changes in the sun. It is really 
only in the last 35 years, since about 1970, that the global 
warming aspect has clearly emerged above these levels of 
natural variability. So----
    Mr. Rohrabacher. And we are only talking about one degree, 
a one degree change, right? And in fact, over these last 20 
years, you are talking about it is less than one degree, 
because your one degree started back in the middle of the 19th 
century.
    Dr. Trenberth. Well, one degree Celsius. Over one degree 
Fahrenheit since 1970.
    Mr. Rohrabacher. Okay. One degree since 1970. Now is it 
possible that there is a natural cycle going on here? Is that a 
possibility?
    Dr. Trenberth. This is one of the things that we can do 
now. Natural cycles also have causes. They--you know, they come 
from somewhere.
    Mr. Rohrabacher. Like sunspots.
    Dr. Trenberth. Sunspots or----
    Mr. Rohrabacher. Okay.
    Dr. Trenberth.--changes in the heat of the ocean or----
    Mr. Rohrabacher. I have only got a little bit of time left. 
Let me ask you--I am sorry, because you know, we are only given 
a very short period of time to ask. What percentage of what are 
called greenhouse gases are created by nature or--and that is 
even leaving the sunspot issue out, as compared to humankind? 
All of humankind produces what, 10 percent of the greenhouse 
gases, five percent?
    Dr. Solomon. Well, this is in my area of research, Mr. 
Rohrabacher, so I would like to respond. On the issue of solar 
activity, we have direct measurements in how the sun has varied 
since 1970. They show very clearly that the solar, in radians, 
changes since 1970 have been very small, much less than the 
changes in the energy budget due to greenhouse gases. You will 
find that figure to----
    Mr. Rohrabacher. Okay. So the greenhouse gases are what 
percentage again?
    Dr. Solomon. Well, greenhouse gas contribution to warming 
far outstrips the solar brightness changes. That is a figure--
--
    Mr. Rohrabacher. Okay. But what percentage of greenhouse--
--
    Dr. Solomon. May I continue----
    Mr. Rohrabacher. No, no, because I have only got a little 
bit of time. I am sorry----
    Dr. Solomon.--because you have asked----
    Mr. Rohrabacher.--I control this time. You don't. I am 
asking what percentage of the greenhouse gases are created by 
human beings?
    Dr. Solomon. Yeah. That is what I was just about to get 
to----
    Mr. Rohrabacher. Okay.
    Dr. Solomon.--actually. Thank you. If you look at Figure 1 
of our Summary for Policy-makers, it actually shows you the 
time series of carbon dioxide, for example, and you will see it 
has increased markedly since 1750----
    Mr. Rohrabacher. I am not asking about that.
    Dr. Solomon. It is almost entirely due to human activities.
    Mr. Rohrabacher. Listen. Listen. Hold on. Excuse me. But 
unless you are going to be honest about this, we are not going 
to have an honest discussion. At least Mr. Alley was being 
honest about it, saying we don't know. If I ask you a direct 
question, what percentage of the greenhouse gases are caused 
naturally rather than by human beings, can't anybody answer 
that directly?
    Dr. Solomon. The CO2 increase is caused almost 
entirely----
    Mr. Rohrabacher. I didn't ask that.
    Dr. Solomon.--by human beings.
    Mr. Rohrabacher. I didn't--listen. I am asking you a direct 
question, what percentage of the greenhouse gases are made by 
human beings and what percentage are made by nature?
    Dr. Solomon. I would say a fair number regarding the 
increase since 1750 is that greater than 90 percent of the 
increase has been caused by human activities.
    Mr. Rohrabacher. That wasn't the question, was it? Why 
can't you--listen, this is very dishonest. You are supposed to 
be a scientist. I have asked you a direct question. Can anybody 
else in the panel be honest about the answer?
    Dr. Solomon. Sir, I am really trying to be honest.
    Mr. Rohrabacher. What percentage of the greenhouse gases in 
our atmosphere and created in our atmosphere are being created 
by nature versus humankind? I have asked you that four times 
now and have been dodged four times.
    Dr. Solomon. No, sir, I am not dodging your question. I am 
sorry.
    Mr. Rohrabacher. Does someone else--I didn't say the 
increase.
    Dr. Solomon. There is a baseline.
    Mr. Rohrabacher. I didn't say increase.
    Dr. Solomon. There is, indeed, a baseline.
    Mr. Rohrabacher. What is the baseline?
    Dr. Solomon. The baseline for carbon dioxide is 270 parts 
per million. What we are now at is about 380 parts per million.
    Mr. Rohrabacher. Excuse me, I am asking--Mr. Chairman----
    Dr. Solomon. That increase is due to human activity.
    Mr. Rohrabacher. Mr. Chairman, I don't--I would like my 
time not to be spent by witnesses not----
    Dr. Solomon. 270 out of 380. I can----
    Chairman Gordon. Well, your time has been up for quite some 
time.
    Mr. Rohrabacher. Well, I wish we could have this--is 
everyone else afraid to answer that question as well?
    Mr. Baird. Would the gentleman from California yield for 
one second?
    Mr. Rohrabacher. Sure.
    Mr. Baird. My belief is that the answer resides in what the 
gentlelady just said in the following sense. If you take a 
baseline, one might presume that the baseline is the natural 
prevalence of CO2, because----
    Mr. Rohrabacher. That is not my question.
    Mr. Baird. No, I understand that, but I am going to get to 
your question----
    Mr. Rohrabacher. I have been trying to get an honest----
    Mr. Baird. Stay with me. I am going to get to your--I am 
going to get to it.
    Mr. Rohrabacher. All right.
    Mr. Baird. And then if you look at where we are now----
    Mr. Rohrabacher. Yes.
    Mr. Baird.--that difference between baseline and where we 
are now would presumably yield the information you are asking 
for, which is what percentage of the carbon is caused by----
    Mr. Rohrabacher. No, no, no. That is not the suggestion at 
all--I mean, that is not the way. I mean, it is a simple 
question, and every scientist that I have asked has said it is 
less than 10 percent of any of the greenhouse gases are caused 
by human activity. And I was just trying to find out whether 
these scientists agreed with the assessment that I have heard 
from all of the other scientists----
    Chairman Gordon. The gentleman's time has expired, but let 
me suggest that if you will put those questions in writing----
    Mr. Rohrabacher. Okay.
    Chairman Gordon.--that the panel will have an opportunity 
to give you the best answer that they can.
    Mr. Baird.

                        More on the IPCC Process

    Mr. Baird. I thank the gentleman.
    I thank the expert testimony.
    Is it correct that there were 450 Lead Authors, 800 
contributing authors and over 2,500 reviewing authors who 
participated in this study or this Report? Is that an 
accurate----
    Dr. Solomon. That is the number across all three Working 
Groups, sir. For Working Group I, the numbers are in my 
testimony, 152 Lead Authors, 400 contributing authors, 600 
expert reviewers.
    Mr. Baird. Was there a----
    Dr. Solomon. The numbers that you quoted are for group I, 
II, and III that you were----
    Mr. Baird. Okay.
    Dr. Solomon.--talking about. We are Group I only.
    Mr. Baird. Thank you. Was there an effort to intentionally 
exclude people who might have a different opinion about global 
warming, or were people allowed to participate and offer 
comments if they disagreed with global warming hypotheses?
    Dr. Solomon. The review process was entirely open. 
Scientists could register on the web. They only had to say who 
they were. They weren't asked anything else, and they were sent 
whatever materials they wanted to review. So it was totally 
open to anyone who wished to review it.
    Mr. Baird. So presumably, if they had had compelling 
arguments and data to persuade their colleagues to reach 
contrary conclusions, they had ample opportunity to do that?
    Dr. Solomon. They had ample opportunity to express their 
views, indeed.
    Mr. Baird. Dr. Trenberth, you seem to want to comment.
    Dr. Trenberth. In my chapter, yes, there were many well-
known, so-called skeptics that participated as reviewers, and 
their comments were all addressed.
    Mr. Baird. So it would not be accurate to suggest that this 
was somehow a biased report, and one could actually see if 
there were--some of my colleagues are raising questions that 
they have heard from so-called skeptics, one could see those 
answers to the skeptics in the Report or presumably in the web 
dialogue that led to the Report?
    Dr. Trenberth. The Report is changed, of course, in 
response to comments, but there are many comments. And in 
addition, all of the comments are responded to in writing, and 
there is a file, there is a great big file at the technical 
support unit, which has the responses to every comment and how 
they were addressed.

                     More on Global Warming Trends

    Mr. Baird. I appreciate that.
    So what you are saying is there is a baseline level of 
CO2 produced by agricultural processes, sea changes, 
et cetera, the normal kind of fluctuations? But beyond that 
baseline, we have seen a substantial increase in CO2 
that correlates quite closely to the production of CO2 
by human-related activity, i.e., predominantly the consumption 
of fossil fuels. Would that be a fair statement?
    Dr. Solomon. Indeed. Figure 1 of the Summary for Policy-
makers shows a constant CO2 for 9.9 thousand years, 
approximately, followed by a dramatic increase in the last 
century, which is essentially entirely attributable to human 
activities.
    Mr. Baird. So to sum--while it is an intriguing question to 
ask, what percentage of the total CO2 budget is 
produced by human activity in terms of gauging changes in the 
CO2 budget, which may correlate to changes in 
temperature. It may, in fact, be the change that is of most 
significance and importance for understanding here, not just 
the base level--the differential percentages, because prior to 
that, presumably, the CO2 production of humankind 
was background, a rounding error, possibly.
    Dr. Solomon. I am afraid I don't know the number exactly, 
but again, in terms of concentrations, 270 parts per million by 
volume in, say 1700, 270 parts per million 1,000 years before 
that, today, 380 parts per million, sir, so----
    Mr. Baird. So could we not assume that is 110 parts per 
million?
    Dr. Solomon. 110-part-per-million increase due essentially 
entirely to human activity. That is what I am trying to say.
    Mr. Baird. So 110 parts per million is what----
    Dr. Solomon. Out of 270.
    Mr. Baird. Correct. So that is about, what----
    Dr. Solomon. A third.
    Mr. Baird.--30 percent. So that may answer the gentleman 
from California's question, I think, and that is what I was 
trying to get to earlier.
    But more importantly, in terms of the global warming 
debate, if you have got that increase presumably in, I think--
we cannot dispute that we produce more CO2. I mean, 
that would be pretty hard to dispute on any credible scientific 
grounds. We also seem to have pretty clear evidence from this 
Report of the increase in temperature. While correlation is not 
causation, correlation can give us some pretty good insights.
    One final question. Skeptics may ask you to prove beyond a 
shadow of a doubt that this global warming, which we are 
observing, is caused by human consumption--production of 
CO2. I don't think that is scientifically possible. 
I used to teach scientific method. I hold a doctorate in the 
scientific field. You can't do it. But that doesn't mean one 
does not act on the best available scientific information. Will 
you care to comment on that?
    Dr. Meehl. Yeah, maybe I can comment on that.
    The real big advance we have seen in the last five years 
with trying to address this question of attribution, that is 
basically your question, you know, how can we attribute, how 
can we be sure that humans are causing this warming, are these 
computer climate models we use, and they have been improved 
quite a bit. We have been putting in single factors that we 
think affected climate over the 20th century, natural and 
human-produced. So we can put in solar variability by itself in 
the model, run it for the 20th century, see how the climate 
system responds. We can put volcanic activity in. We get a big 
volcano going off that cools off the climate for a couple of 
years and see how that responds. We can put in other forms of 
air pollution, sulfate aerosols, which are small particles that 
reflect sunlight, so that is a cooling effect. We can put that 
in separately and see how it affects the climate. We can put in 
increases of greenhouse gases produced by human activity and 
see how that affects the climate. So we can deconstruct the 
20th century climate in a way that we just couldn't do taking 
observations, because the observations you are seeing out the 
window are a combination of all of these factors wrapped up 
together. There is a great use of these models as tools, so we 
can actually look at each of these things separately and in 
combination to see how they contributed to what we observed 
over the 20th century. And as was alluded to earlier, the 
results from these studies, the first started to be done about 
five years ago, and we have many more now that we assessed, 
show that most of the warming that we observed in the first 
part of the 20th century was natural. Not many volcanoes were 
going off. We had an increase of solar output. Then we had the 
level period from the 1940s to the 1970s when the big increase 
in industrial activity after World War II produced a lot more 
air pollution. That was a cooling effect, but the increase in 
greenhouse gases were still going up. That was warming, but 
they about balanced until about the mid-1970s. Then the ongoing 
increases of greenhouse gases plus some efforts by 
industrialized countries to reduce visible air pollution then 
produced the big warming we have seen since the 1970s.
    So I think by being able to do these kinds of studies with 
these calibrated models, we can make this statement that it is 
very likely that most of the warming we have seen in the last 
half-century or so is due to human activities. That is where 
that comes from.
    Mr. Baird. I appreciate that and yield back.
    Chairman Gordon. Thank you, Dr. Meehl.
    Mr. Sensenbrenner is recognized for five minutes.
    Mr. Sensenbrenner. Yes. Thank you very much.
    I would like to ask members of the panel to rank the three 
big greenhouse gases, CO2, methane, and NOX as to 
which is the biggest culprit, which is the second biggest, and 
which is the third biggest.
    Dr. Solomon. Figure 2 of the summary shows that explicitly, 
so what you can see there is that carbon dioxide is the largest 
contributor. Methane is the second. Nitrous oxide is also 
significant, and that is shown in the middle of the second 
column. And the halocarbons also contribute. Tropospheric ozone 
does as well.
    Mr. Sensenbrenner. Okay. Now----
    Dr. Solomon. You can see the ranking, sir.
    Mr. Sensenbrenner.--by looking at your Figure 1, Dr. 
Solomon, CO2 has gone up about 40 percent since 1750 
whereas methane has gone up, by my rough figures, about 130 
percent. What is causing the difference between the increase of 
human activity is the culprit on all of that?
    Dr. Solomon. The sources are different. In the case of 
methane, the primary sources are agricultural, whereas in the 
case of carbon dioxide, the primary sources are fossil fuel, so 
they are coming from different things.
    Mr. Sensenbrenner. Does that mean that to stop this huge 
growth of methane, we better put catalytic converters on the 
back of cows?
    Dr. Solomon. Certainly, animals are one contributor to the 
increases in methane. You are quite right. There are----
    Mr. Sensenbrenner. Now you are hitting the Wisconsin 
economy right between the horns.
    Dr. Solomon. I can always tell you I love your cheese, sir. 
I don't know what else to say.
    Mr. Sensenbrenner. Well, we better make sure that there are 
cows there to produce it, and we appreciate your patronage.
    Dr. Trenberth.
    Dr. Trenberth. Yes. I am from New Zealand, and it turns out 
New Zealand is pretty unique in that it emits more methane than 
carbon dioxide because of all of the sheep and cows in New 
Zealand, and there is a tremendous amount of research going on 
on exactly that topic and how to change feed in order to reduce 
methane coming out of the mouths and the other end of animals.

             Greenhouse Gas Production: Country Comparisons

    Mr. Sensenbrenner. Okay. Have you done any figures or any 
calculations as to which particular countries are culprits in 
emitting more or less CO2 and methane relatively? 
Meaning, do you see more methane in Europe and more CO2 
in North America, or don't you know?
    Dr. Trenberth. There are charts on those. I don't have 
those numbers at my fingertips. And the other revealing factor, 
which you may want to look into, is the amount per capita, and 
I do know that the United States leads the world in both 
categories. And that per capita, the United States emits about 
two and a half times more carbon dioxide than in Europe, for 
instance, and about 10 times more than China and about 20 times 
more than India, but of course, the per capita aspect and the 
number of people then makes a very big difference, and so that 
is another important----
    Mr. Sensenbrenner. Well, now, you know, I was the head of 
the Congressional Observer Delegation to Kyoto, so I went and 
watched all of that stuff. One of the meetings that my 
bipartisan delegation had was with the Chinese delegation. And 
they told Mr. Dingell that they weren't going to cut down on 
their greenhouse gas emissions, no way, no how. Mr. Dingell 
kept on going forward for 20 years, seeing if they would change 
their mind, and if I didn't tell him to stop, he would still be 
there, and we would probably be up to the year about 15,000. 
The Chinese Government, last week, when your report was coming 
out, reiterated the fact that it was going to stonewall dealing 
with this issue because it needed to burn more hydrocarbons in 
order to develop its economy. If you have the world's biggest 
country and the world's most rapidly developing economy not 
participating in this and the United States, for example, doing 
what has been suggested here, have you thought about the 
economic impact on where jobs go, meaning to China and away 
from the United States?
    Dr. Trenberth. It is not for me to really say that, but I 
would emphasize, indeed, that this is a global problem, and so 
whereas other countries are concerned about the United States' 
emissions, indeed, I think we need to be concerned about other 
countries' emissions and therefore the international 
negotiations are an important part of this problem.
    Mr. Sensenbrenner. But with all due----
    Chairman Gordon. The gentleman's time has expired.
    Mr. Udall.

                            Climate Research

    Mr. Udall. Thank you, Mr. Chairman.
    I would note for my colleague from Wisconsin that Dr. 
Bartlett, who has just recently traveled to China, had some 
very interesting discussions with the Chinese, and I am going 
to maintain my own time, but I am hoping to cue Dr. Bartlett, 
and perhaps when he has some questions, to talk about what the 
Chinese are doing. So their actions are speaking, certainly, as 
loud as their words. They understand that the present path 
cannot be maintained in any sustainable fashion.
    Dr. Trenberth, I want to turn to your testimony. You 
restate the Report's findings that we're already committed to a 
significant level of climate change in that you believe we need 
to mitigate the effects of the coming changes. And I might like 
to, in that spirit, note that yesterday I introduced H.R. 906, 
the Global Change Research and Data Management Act of 2007, 
along with my good friend and colleague from South Carolina, 
Mr. Inglis. And this bill updates the existing law that 
formally established the U.S. Global Change Research Program in 
1990, and it would help reorient the research program to be 
more user-driven, which would help local and state and regional 
and national policy-makers make more informed decisions.
    Would you speak to that from your point of view? Do you 
believe that improving these regional models would enable us to 
produce these vulnerability assessments that you reference in 
your document?
    Dr. Trenberth. One of the things that we struggled with in 
our chapter in dealing with observations is that in a number of 
countries, in fact, observations, especially the surface 
observations, are decaying over time. And as a recent National 
Academy of Sciences report has stated, there are real risks in 
losing a lot of space-based observations in the future. Space-
based observations are very difficult to deal with, as well, 
because every time you put a new satellite up with a new 
instrument, it is very hard to know exactly how those 
measurements relate to the previous set of measurements. And so 
it depends on whether these satellites have been launched for 
climate purposes and whether the observations are adequately 
calibrated or whether they are launched for other purposes, 
such as weather, where those issues are not so great. And what 
the science community is certainly urging is that we pay more 
attention to these kinds of issues and the degradation that is 
going on in the observing system, because this builds the 
information base as to what is going on and also why. So in 
this case, we are not just talking about observations of 
temperature and precipitation, and so on, but also the 
observations on why the climate is changing, what is happening 
to the composition of the atmosphere, what is happening to the 
sun, and so on, and I think there is a very compelling case 
that we need to do more in this area to track why this winter 
in the East Coast was so warm up until recently, why there has 
been no snow and it has been very warm in Europe, and they are 
having trouble with the World Cup Skiing, what the role of El 
Nino is in this, which is playing a role, understanding the 
variability and the climate change aspects and tracking what is 
going on. This relates to natural variability as well. If it is 
natural variability playing a role, we should be able to 
measure it and account for it. So if the ocean currents are 
changing, the Gulf Stream is changing, we should be able to 
measure that and assess its impact and whether or not there is 
going to be a shut down in the Gulf Stream and so on. So I 
think a compelling part of what we need to do, also, is to 
build an information base and a climate service that addresses 
these kinds of concerns.
    Mr. Udall. Doctor, is it fair to say what you are proposing 
and suggesting we could do is gathering and assessing and 
concluding about the data, it is--you are not involved in the 
processing, okay, what do we do about carbon emissions? And the 
reason I am asking you that is to promote the idea behind this 
legislation I proposed, which is to make better use of our 
resources, be more efficient in this whole area of research, 
and then we can continue to have the debate that we are having 
here and all over the world.
    Dr. Trenberth. Yeah, the mitigation aspects are dealt with 
in Working Group III, and I would urge you to wait for their 
report in May of this year. It is not an area where I am an 
expert. All I can say is, for myself, I have put solar panels 
on the roof of my house.
    Mr. Udall. Thank you.
    Dr. Solomon, somebody suggested that--particularly on the 
heels of Mr. Sensenbrenner's comments about methane, that 
humans are actually temporary carbon sinks and that we could 
think about ourselves in that regard, but I have never seen a 
study on the balance between humans as carbon sinks and the 
methane that we may or may not emit. Be that as it may, what 
surprised you of the IPCC process?
    Dr. Solomon. That is an interesting question. I knew pretty 
well what to expect, having been involved in it for a very long 
time. I think what surprised me the most was actually how much 
progress we have, in fact, made from remarkable new databases, 
from satellites on issues, such as the effects of aerosols, as 
Kevin was saying, the improvements in observations. Indeed, 
there is more to be done there, but we just have so much better 
information now. The advances in modeling, I was very 
impressed, actually, by the degree of progress we were able to 
make in this assessment compared to the past one. It surprised 
me.
    Chairman Gordon. Thank you, Mr. Udall. Your time is 
expired.
    Mr. Calvert, you are recognized for five minutes.

                          Carbon Sequestration

    Mr. Calvert. Thank you, Mr. Chairman.
    I am going to go at this in a different direction. I think 
that there is pretty much unanimity that there is climate 
change taking place, global warming taking place, and this 
committee is gathering information, scientific information 
within our jurisdiction. And I assume that information will be 
shared with other committees that will have the jurisdiction to 
regulate certain industries, such as the coal industry, the 
automobile industry, the hydrocarbon-fired energy sources 
within the United States. And so it is important that we try to 
get it right, because the unintended consequences of taking bad 
information and trying to make policy is going to have dramatic 
effects on the economy of this country and certainly for the 
rest of the world. And so when Mr. Rohrabacher, for instance, 
is asking the question how much of a percentage, for us laymen, 
is greenhouse gases relative to natural sources, that is an 
important question, because--and also, the question of what 
countries and what regions have an increase relative to natural 
sources for--we have a better understanding of how we go about 
that problem. But it has been said that the United States 
produces 25 percent--or uses 25 percent of the energy in the 
world, and it is about four percent of the world's population. 
So you know, you could say that the United States, 
overwhelmingly, has the most responsibility to regulate its 
economy in order to meet its responsibilities, especially under 
the Kyoto accord, which I went to with Mr. Sensenbrenner a 
number of years ago. So we have got to get it right, because I 
would suspect the four of you all agree that with the summary 
of the report, 90 percent confidence that human activity is the 
cause of global warming. Would you say that all four of you 
agree to that basic concept, since you are here, obviously, 
testifying for the majority? And so if, in fact, that is 
correct, how do we go about tackling this problem? And I think 
that that is really what this Congress is going to be trying to 
answer, whether we go into mandatory caps, which was mentioned 
by the Speaker, or, as I believe, incentives in the economy to 
bring on new industries that I think will have the same result 
in the long-term and in the short-term of having--the result of 
having less greenhouse gases. In that, China--the issue of 
China has been brought up. I believe China, right now, is 
opening a new coal-powered plant once a week. And is that 
approximately correct?
    Dr. Trenberth. It is less than every three days.
    Mr. Calvert. Less than every three days. The United 
States--the largest energy source within the United States is 
still coal, based on our base load power. And I know we are 
trying to get the clean coal technology. Doctor, do you think 
that that is possible, that we can sequester the CO2 
that is put out by the coal industry? Do you think that is a 
possibility and continue to use coal?
    Dr. Trenberth. This is not an area where I am an expert. It 
is certainly an area where that potential is, I believe, 
growing. And there is, of course, some cost to that, but it 
needs to be balanced against the cost of not doing it as well. 
But----
    Mr. Calvert. Well, right now, the renewable energy sources 
in the United States are approximately less than five percent. 
Ninety-five percent of all energy source in the United States 
is hydrocarbon-based or nuclear-power-based. Twenty percent of 
the base load in the United States is nuclear. The rest of it 
is either coal or gas-powered plants. And so in order for us to 
really meet the goals that are outlined within the scientific 
information that is being represented to us, without coal or 
nuclear power, is that possible? I mean, can we have a 
sustainable economy without coal or nuclear power?
    Dr. Solomon. You know, I would just like to emphasize, sir, 
that this group are physical scientists. That is all we are. We 
are not economists and----
    Mr. Calvert. No, and I understand that. And you are 
providing the information that we, as policy-makers ultimately 
have to make a determination. Because you know, the automobile 
industry, the coal industry, the manufacturing industry in this 
country are really depending upon getting it right, getting the 
right science to us. You know, something was talked about El 
Nino earlier this year. We were supposed to have an El Nino 
effect in southern California this year. Unfortunately, it 
didn't happen, and we are having one of the largest droughts we 
have ever had. So sometimes, we just don't get it right. And so 
hopefully we get it right when we make these types of policy 
decisions.
    With that, I yield back the balance of my time.
    Chairman Gordon. The gentleman's time is expired.
    Ms. Hooley is recognized for five minutes.

                    Advancements in Climate Research

    Ms. Hooley. Thank you, Mr. Chair. I want to thank all of 
the panelists for being here today.
    Dr. Solomon, I have a question. There seems to be a big 
change in the certainty assigned to this Report compared to the 
2001. Was that because of modeling or was that because of data 
collection and observation? And was there----
    Dr. Solomon. Certainly in both areas. We have really seen 
advances with, by far, more models, models with better physics 
in them, models with improved representation of processes, such 
as sea ice and the carbon cycle. We made advances in those 
areas. In terms of observations, there have also been many, 
many advances in observations. A lot of satellite information 
has become available that we just didn't have before. We now 
have satellite measurements of sea level rise, for example, for 
the last 10 years. We also have satellite data that allows us 
to say things about the ice sheets, as Dr. Alley was talking 
about. And you know, we have also had more warm years, as I 
tried to emphasize in the testimony. And Dr. Trenberth also has 
emphasized. So the fact that 11 out of 12 of the last years 
have been among the warmest is a remarkable and very 
interesting bit of information.

                         Cooling in Antarctica

    Ms. Hooley. Thank you.
    Dr. Trenberth, you say the planet is ``running a fever.'' 
Are there any areas that can get colder instead of warmer as a 
result of climate change?
    Dr. Trenberth. In the interior part of Antarctica, it seems 
as though it may have even cooled slightly, and we believe that 
that is a unique part of the globe because of the ozone hole 
that occurs over Antarctica. And so it has created some changes 
in the atmospheric circulation there that has led to quite warm 
conditions in the Antarctic peninsula and the southern part of 
South America, the decay of the ice shelf occurred in that 
region, but at the same time, perhaps even slightly cooler 
conditions on the interior part of Antarctica. So that is one 
unique area.

                  Impact on the Western United States

    Ms. Hooley. Okay. And Dr. Alley, in your testimony, you 
described the effect of loss of snow pack and--that it will 
have on the wintertime water supplies in the west. And since I 
am from the West, can you elaborate the impact on our Western 
states?
    Dr. Alley. I really can't, because I am a physical 
scientist as opposed to an impacts person. What we do observe 
is that there has been a shift to earlier snowmelt, and what 
one sees in projections of the future is if that continues so 
that you lose more and more of your snow pack. And you well 
know, as a Representative of a Western state, that the snow 
pack has been important in maintaining stream flow. Now in 
terms of what that means for the salmon versus the farm or 
versus the irrigation versus drinking water versus recreation, 
that is clearly for someone who is wiser than me. But I think 
you are well aware, and you are probably wiser than me on these 
issues.
    Ms. Hooley. I don't know about that.

                     Thermal Expansion of Seawater

    Dr. Meehl, would you talk a little bit about the thermal 
expansion of seawater and the effect it has on global sea 
levels?
    Dr. Meehl. Yes, water has this interesting property that as 
it warms up, it expands. And so as the warming that is taking 
place in the climate system penetrates into the ocean, you get 
ever-increasing layers of ocean water expanding. And as this 
warming works its way down into the ocean into a deeper and 
deeper layer, you get more and more thermal expansion. So when 
we talk about the commitment of climate change, committed 
warming, it is on the order of centuries. In other words, we 
have already committed ourselves to centuries more sea level 
rise from what we have already put into the system just because 
it is going to take centuries for that warming to work its way 
all of the way down through the depth of the ocean. And as long 
as you still have warming that is working its way down, you are 
going to have an ever-increasing volume of ocean warming up and 
expanding. So I think that is an important and probably one of 
the best things we can quantify in terms of sea level rise is 
thermal expansion. These other aspects related to ice sheets 
and things like that we have less confidence in.

                       Mitigating Climate Change

    Ms. Hooley. How much time do we have to turn back the clock 
or do something about it?
    Dr. Meehl. Again, that is kind of a mitigation question, 
and that is, frankly, out of my area of expertise, but I think 
just what we can say from the scenarios we have looked at for 
the 21st century where we see that what we do makes a 
difference. If we go on a low-emission track, we get less 
warming. If we go on a high-emission track, we get more 
warming. And the longer we wait to do something, the worse the 
problem gets, the harder it is to try to do something about it. 
So I think those kind of very general conclusions you can draw 
from the projections chapter in the AR4. In terms of details on 
exactly how to mitigate the problem, this combination 
mitigation and adaptation, that is out of our area of our 
expertise.
    Ms. Hooley. I would like to ask the other panelists if you 
can, what do you think about how much time we have to turn this 
around or change things or try to lower those emissions 
significantly?
    Dr. Trenberth. Let me comment. As is clear from the 
observations, there are already changes underway. I mean, they 
are already with us, and some of those changes are really, 
perhaps, already having devastating effects. We mentioned 
drought, and drought has become widespread in the subtropics in 
particular, and parts of Africa have suffered greatly from that 
and our understanding is building now that a component of this 
is very likely associated with the global warming that is going 
on. So from the standpoint of Africa, maybe it is already too 
late.
    Chairman Gordon. The gentlelady's time has expired.
    Ms. Hooley. Thank you.
    Chairman Gordon. Dr. Bartlett is recognized for five 
minutes.

                       Ocean Circulation Changes

    Mr. Bartlett. Thank you very much.
    Mr. Udall mentioned my recent trip to China. I was very 
surprised and pleased when they began their discussion of 
energy and talking about post-oil. They get it. Somehow, we 
don't in this country. I would suggest that there ought to be 
enormous common cause between those of us who are concerned 
that there will not be a limitless supply of oil in the world 
and those of us, and I am in both categories, who are concerned 
that we are involved in global warming. And I would think that 
we can harness our joint energies and get more attention to 
this.
    My colleague, Mr. Rohrabacher, is somehow concerned, I 
believe, that because humans produce only about 10 percent of 
the greenhouse gases that what we do, maybe, doesn't matter 
much. And I have a little illustration that may help us to 
understand that the total amount of gases up there may be 
somewhat irrelevant relative to what we can do to change that. 
If you have a seesaw with 100 pounds on each end and you put 
another 100 pounds on one end, that is really going down, isn't 
it? If you put 1,000 pounds on each end as the seesaw and you 
put another 100 pounds on one end, it is still going down, 
isn't it? So the total amount of greenhouse gases that are up 
there may be somewhat irrelevant as to our contribution. 
Obviously, where our Earth's temperature is, it is a balance 
between the heat we gain from the sun and the heat we lose. And 
you know, a very small change can produce enormous effects. I 
was stunned the other day when I read, and I would ask you if 
this is true, that in the last ice age the world was five 
degrees centigrade, that is nine degrees Fahrenheit, cooler 
than it is today. That is correct? And for those that think, 
gee, a degree or two, my living room goes up and down three or 
four degrees. That doesn't matter much. Three or four degrees 
in the world may not matter much. But nine degrees cooler 
Fahrenheit, and we were in an ice age. With ice sheets coming 
down to southeast Ohio, you can see the terminal there from 
those, someone was asking about where it is warmer and where it 
is cooler. There is an ironic thing that could happen as the 
result of global warming, that is that the British Isles and 
northern Europe could become very much colder because we have a 
big conveyor belt called the Gulf Stream, which carries heat 
from the tropics up there. And obviously, water is not piling 
up up there, so it has to come back. And it comes back, because 
it gets more dense and it drops down. And one of the things 
that is happening up there may prohibit this increase in 
density and that is the melting of ice up there, which produces 
fresh water, which is very much lighter than the salty water. 
And so if we have a little bit more global warming, we could 
shut down the Gulf Stream. And if you look at where England is 
on the globe, it is up about central Canada. I had to stop for 
refueling in the Emerald Isle. And that really is incredibly 
green and warm there in Ireland compared to what it would be if 
it weren't for the Gulf Stream. So we can have enormous changes 
in climate in certain parts of the world from relatively small 
changes in temperature.
    I was in Antarctica. I have been to the South Pole twice, 
and of course 90 percent of the world's ice is found there and 
70 percent of the world's fresh water is found there in 
Antarctica. We have a circumpolar stream there, a current, that 
kind of keeps the warm waters from the north, well, it is north 
down there, from coming in. Are there any hints that the global 
warming may interfere with that circumpolar current down there? 
And if that is true and warmer northern waters could come down, 
is it possible that we could see very much accelerated changes 
in temperatures down there? And by the way, if that ice pack 
melted with all of the others, the ocean levels would rise 
about 200 feet is my understanding. But 60 percent of the 
world's population lives within 200 feet of sea level. Is there 
a potential that global warming could somewhat interfere with 
that circumpolar current down there, which is keeping the warm 
waters out and keeping Antarctica the refrigerator it is?
    Dr. Meehl. Maybe I could try taking a crack at this. All of 
these ocean circulation changes you mentioned, and you have a 
real good knowledge of it, obviously, are things that we are 
really concerned about, obviously, as scientists. And one of 
the things that is really getting a lot of attention, due to a 
certain Hollywood movie that we all really like, was this 
sudden shutdown of this overturning circulation in the Atlantic 
that you mentioned that the Gulf Stream is a part of. And if it 
suddenly shut down, the idea was that you would suddenly get a 
lot more colder in the North Atlantic, because you wouldn't be 
carrying all of that heat up into the North Atlantic that the 
conveyor belt transfers. So we have looked at that in all of 
the models that we have run so far. No model that we have run 
yet, for the 21st century, for the present century, shows a 
sudden shutdown of this overturning circulation, this conveyor 
belt. They all show a slowing down of the conveyor belt for the 
reasons--exactly the reasons you mentioned. It gets warmer and 
less dense in the high-latitude North Atlantic, therefore you 
don't get as much sinking, and you just kind of slow down this 
conveyor belt circulation. But, of course, then that would 
contribute to less heat transport to the North Atlantic. You 
think, well, maybe that would give a cooling. When it turns 
out, to get that slow down, you have to have so much of an 
increase of greenhouse gases in the atmosphere that the warming 
itself from those greenhouse gases just swamps, it overwhelms 
any small decrease of northward heat transport you get from the 
slowdown of this overturning circulation. So we say, in fact, 
it is very likely that the overturning would slow down. It is 
very unlikely that it would suddenly seize up and stop, at 
least in the 21st century. And that is even taking into account 
possible contributions from melt water from Greenland and other 
things that would add to this decrease in density.
    Chairman Gordon. The gentleman's time has expired--oh, I am 
sorry.
    Dr. Meehl. I was just going to say, beyond 2100, we are not 
as sure, because there may be odd things in the system we 
haven't anticipated, but for the time periods we looked at, 
especially to 2100, we don't see that.
    Mr. Bartlett. Thank you.
    Chairman Gordon. The gentleman's time has expired.
    Chairman Miller is recognized for five minutes.

                            Tropical Storms

    Mr. Miller. Thank you, Mr. Chairman.
    Dr. Trenberth, the IPCC Report and your testimony both 
referred to one result of global climate change, global 
warming, as being the intensity of tropical storms. In the fall 
of 2005, after the hurricane season that we had that included 
Katrina, of course, and several other catastrophic storms, 
Category 4 and Category 5, I can't recall how many, but 
several, and they were stunning to look at in the satellite 
view of how large and perfectly symmetrical they were. The 
press wondered whether there was a relationship between global 
climate change or global warming and that hurricane season. And 
many made many requests of NOAA and NOAA produced a hurricane 
scientist named Chris Landsea, who treated those questions as 
if they were an urban legend and was very dismissive of that 
possibility. And as a result, the press kind of went away on 
that topic and concluded that was not serious science that 
anyone had that question. In fact, there were others within 
NOAA, other scientists, who said that yes, the formation of the 
tropical storms may be cyclical, as Dr. Landsea had said, but 
the intensification is very much related to temperature. What 
was the state of the science in the fall of 2005 and what is it 
now on the relationship between the intensity of tropical 
storms and water temperature?
    Dr. Trenberth. Indeed, the 2005 season, in fact, it began a 
little before that, even with the 2004 season where four 
hurricanes hit Florida and there were ten typhoons that ended 
up hitting Japan, have raised this question, and there has been 
a great deal of research that has gone on even after our 
report, although our report, I think, is still a fair 
assessment of the current situation. And we had a breakout 
group that dealt with this in Paris, and the statement on page 
8 of the SPM is fully consistent with all of the literature 
that we have reviewed in our report. And maybe I should read 
it. It says, ``There is observational evidence for an increase 
in intense tropical cyclone activity in the North Atlantic 
since about 1970, correlating with increases in tropical sea 
surface temperatures.'' This is one thing where there is 
widespread agreement that if the sea temperatures go up, you 
get more activity. And we are seeing that in the North 
Atlantic. And then the second question is why are the sea 
temperatures going up. And certainly, on a global basis, we 
know that there is a component of that. We believe it is close 
to about one degree Fahrenheit now associated with the 
increases in greenhouse gases. And then you can argue about how 
much of that is occurring in the hurricane regions and so on. 
There is some natural variability.
    Another key part of our statement also recognizes that 
``multi-decadal variability and the quality of tropical cyclone 
records prior to routine satellite observations in about 1970 
complicate the detection of long-term trends in tropical 
cyclone activity.'' And so this is saying that, indeed, a lot 
of natural variability as well as the greenhouse gas-induced 
trends that are playing a role, and in addition, the database 
that we have is not as good as we would like. And so there are 
some uncertainties there. But nonetheless, there has been an 
increase in activity.
    Now the theoretical understanding suggests that, indeed, 
there will be an increase in activity of some sort, and that 
can be manifested in a number of ways. You can have increased 
numbers, increased intensity, increases in size, increases in 
duration. And we don't have measures of all of those. They are 
not in the historical record. We don't have measures of size 
adequately. And so this is a very important question, but there 
are a number of uncertainties that remain.

             Social and Economic Impacts of Climate Change

    Mr. Miller. Okay. One more question for any of you who wish 
to answer.
    There have been several references to economic consequences 
dealing with greenhouse gases in opening statements and in some 
of the questions that were propounded to all of you. Last fall, 
the British government released an economic report by Sir 
Nicholas Stern, who is a former World Bank economist, a 600-
page report that I admit to not having read. But it concluded 
that global warming could leave millions homeless and result in 
as much as a $7 trillion, or 20 percent diminution in the size 
of the world's economy and cause the greatest market failure--
greatest economic failure in the world's history comparable to 
the Great Depression and worse than the Great Depression, worse 
than the world wars. Knowing what you know about the 
consequences of global warming of the forecast, does that sound 
right?
    Dr. Solomon. I would really urge you to wait for the 
Working Group III assessment. Those are the people who would be 
qualified to make that kind of statement. Also, Working Group 
II, I believe, will be dealing with that. This is simply not 
something that is covered in the Working Group I reports. Sir, 
I am sorry, but we don't have the expertise to respond to this 
question.
    Chairman Gordon. The gentleman's time has expired. Dr. 
Ehlers is recognized for five minutes.

                        More on the IPCC Process

    Mr. Ehlers. Thank you, Mr. Chairman, and first of all, just 
a little housekeeping. I did a quick calculation on the 
question Mr. Rohrabacher asked, and my estimate is that 35 
percent is the answer.
    The other comment I wanted to make, Mr. Chairman, is that I 
personally appreciate the fact that the Speaker of the House 
appeared before this committee and made some comments. First of 
all, this is an extremely important issue, but also I think 
that any time the leadership pays any attention to this 
committee is good because sometimes--personally, not publicly--
this is the first time I said it publicly, but sometimes I 
think this is the Rodney Dangerfield Committee. We do 
incredibly good work here and don't get the respect we should. 
So I hope this is a sign----
    Chairman Gordon. We had a lot of bills on the Floor today--
--
    Mr. Ehlers. I know.
    Chairman Gordon.--yesterday, and previously that I think 
will demonstrate that Rodney is out of town.
    Mr. Ehlers. I hope that he has moved out permanently.
    Having said all of that, just first of all, I want to thank 
you for being here. A quick question anyone could answer: this 
is of course a summary that you have prepared. When will the 
full report be published? Do you know? Dr. Solomon?
    Dr. Solomon. The full report is being copy-edited and laid 
out. It will be available probably around May.

                    Global Impacts of Climate Change

    Mr. Ehlers. All right. Thank you.
    Just a few quick comments. First of all, I think it is very 
clear that global warming is occurring, and we can argue about 
how much and the causes and so forth, but it is occurring. The 
next question is it anthropogenic? It definitely seems to be, 
either through industrialization or through farming, as we have 
heard.
    A couple of questions: what about global climate change, by 
which I mean the whole picture? We seem to be obsessed here 
this morning about global warming, but I am much more worried 
about climate change. For example, I am from Michigan. We would 
certainly welcome a bit of global warming in Michigan, 
especially this past weekend when I got up Monday morning and 
it was nine-below with a wind chill of 21-below. But I wouldn't 
want global warming at the expense of losing rainfall in 
Michigan and having it turn into a place like Kansas or--I 
guess I can say Texas since our Ranking Member isn't here.
    That really points to the political difficultly we have. We 
have two political problems. One is, if we are talking just 
about global warming, which is related to human activity, 
industrialization particularly, that is an immense political 
problem, globally, to try to get people to cut back. And I was 
opposed to the Kyoto Agreement because it gave a free card to 
China, and I knew China was going to be one of the biggest 
contributors. So that is one political problem. The other one 
is that global climate change is going to be good for some 
areas of the planet and bad for other areas of the planet.
    Now, how far along are you in determining the effects of 
global climate change and the impact that it is likely to have 
on different parts of the globe? How far along are the models 
in determining that and with what accuracy?
    Dr. Meehl. This is sometimes referred to as the winners and 
losers issues. We didn't really address that in the Working 
Group I Report. That is really a Working Group II impacts 
question. But when I get asked this question--you know, we have 
said a lot about changes in weather and climate extremes. And 
one of the changes we have seen in extremes lately is a 
decrease in the number of frost days, in other words, nighttime 
temperatures going below freezing. This is something we have 
already observed, and in the models, we project this to 
increase in the future, that you will have warmer nights, and 
less nights below freezing.
    So you can say, well, maybe that is a good thing because 
maybe that will expand the growing season length, and we do 
show in the report that the growing season gets longer because 
of that. You have later frost in the fall and then earlier 
warming up in the spring. But then there are things like insect 
infestations that are affected because, if it doesn't get as 
cold in the winter, you don't kill off as many of the bugs in 
the wintertime. They live though the winter, and then you have 
severe problems with insect infestation. Out in Colorado, we 
have seen a lot of problems with that with pine beetle kill.
    So it is kind of a mixed bag, a lot of times. There are 
some things that may be better, but then there are other 
unforeseen consequences, and I think that is what makes me, 
personally, nervous because when we are moving into a new 
regime, which we are, which we have never really observed 
before, there are things that we can anticipate that could have 
good consequences, but other things that have bad consequences. 
And that is the part, at least, that hopefully Working Group II 
will address in more detail.
    Mr. Ehlers. Well, that is precisely my concern because in 
our arena--now, I am a scientist, but I ended up in this arena. 
That is where the decisions are made in those issues, and we 
need the information to make intelligent decisions, and the 
sooner you can develop comprehensive models that can deal with 
those issues, the better off we will be in this arena.
    Chairman Gordon. Thank you, Dr. Ehlers. You got bonus time 
for nice comments. Mr. Lipinski is recognized for five minutes.

                        Managing Water Resources

    Mr. Lipinski. Thank you Mr. Chairman. Thank you for holding 
this hearing on this very important topic that I am very 
hopeful will move forward in this Congress in a bipartisan 
fashion. I am working on this issue, and I appreciate the 
testimony that all of you have given. I understand that your 
role here is to talk about the science behind what is going on. 
In the future I am sure we will have many panels where we will 
talk about what can be done to mitigate this, but than you for 
bringing you expertise to us today.
    I want to ask--I am from the Chicago area, and I represent 
part of Chicago, and I want to ask Dr. Trenberth: you talked 
about managing water resources in the future as climate change 
progresses. Now, I am just wondering if there is anything you 
can tell us, perhaps not, but I was wondering if there was 
anything you could tell us about how these atmospheric changes 
may effect Chicago and other areas like that. I mean Chicago 
uses about two billion gallons of water per day, from Lake 
Michigan. Is there anything you can tell us about that?
    Dr. Trenberth. As the climate warms, the water-holding 
capacity of the atmosphere goes up about four percent per 
degree Fahrenheit, and we find from the observations that this 
is actually happening over the ocean. Over the land, it is 
happening at a slightly less rate. But it means that there is 
more water vapor in the atmosphere. Now when you have a storm, 
the storm reaches out and grabs the available water vapor, 
concentrates it and dumps it down in the form of rainfall. So 
with more water vapor in the atmosphere, you expect that when 
it rains, it is going to rain harder, or even when it snows, it 
can snow harder, and that is what we are actually seeing. And 
so you get heavier rainfall events. This is what is also 
predicted in the models. However, when that happens, you also 
deplete the water vapor in the atmosphere, so you change the 
frequency of these events, and it may be that they are more 
intense but they may be a little bit fewer and farther in 
between, and so you have a greater risk of drought in between. 
There is a little bit of extra heat available, so the drying 
effects of that exacerbate drought.
    Ironically, then you get both extremes of what we call the 
water cycle that are affected by global warming, and it means 
that the challenge of water resource management is that they 
have times when they have got too much of a good thing, too 
much rainfall, a risk of flooding, and then there are times in 
between when they don't have enough. This is particularly what 
that comment refers to: the changing character of 
precipitation, the changes in snow to rain, it also means that 
you have less snow pack going into the spring and summer, which 
is when you most need the water, so that aspect of management 
is another key part of it. And so these are the factors that 
play into the water management challenge.

                        More on Climate Research

    Mr. Lipinski. Thank you, and I want to ask Dr. Alley, you 
mentioned that the apparent shrinking of the large ice sheets 
was an unexpected finding. Why was this unexpected and can you 
point out any other findings that came out as a big surprise to 
you?
    Dr. Alley. We had a longstanding debate in the community. 
How fast can ice sheets do interesting things? They are very 
large; they look sluggish. And yet you look back at the history 
of the climate, back to the Ice Age, and most of the time ice 
sheets were boring, and occasionally they were really 
interesting. And so we have had this longstanding debate in the 
community are the ice sheets going to be boring or they going 
to be interesting, and the assessed science of the report said 
the most likely outcome is boring, and they have been 
interesting, and that, probably, for me was the most surprising 
thing that came out of it.
    The other thing that I see, looking at the report, is how 
good the science has become on so many things. So the early 
IPCC reports picked out sensitivity. You are at double 
CO2. How much does the climate warm? And it was 
based on moderately weak evidence. It was good science, but 
there just wasn't a lot of it. And as the amount of science has 
been produced, as more research has been done, more models, 
more observations, the quality of the support, the strength of 
the conclusions has just become tremendously greater. So there 
are a few, you know, gaping holes that we would love to fill, 
but primarily the quality of the science is just superb. It is 
just outstanding, and results are getting to the sort of pound-
on-the-table-this-is-right stage. Thank you.
    Chairman Gordon. The gentleman's time has expired. I am 
told that the gentleman from South Carolina, Mr. Inlgis is next 
and recognized for five minutes.

                      Opposition to Climate Change

    Mr. Inglis. Thank you, Mr. Chairman. I am one of those 
people that used to poo-poo global warming. It seems to me it 
is hard not to be persuaded with the evidence that you have 
been talking about. There is always the question of causation, 
so I would make the analogy to the doctor who determines it is 
genetics that determines longevity. Doctor, would it hurt us to 
diet and exercise? Not likely to hurt us. So it is not likely 
to hurt us to take some action, as long as we can do that in a 
way that maintains balance with other things that we have got 
to do in life, like make a living and provide for our families 
and all of those kinds of things. So it seems to me the key is 
to work cooperatively to solve some of these challenges.
    It is going to be hard, though. I read yesterday, Mr. 
Samuelson's piece, Mr. Chairman, that I asked to insert in the 
record. It is Robert J. Samuelson, ``Global Warming and Hot 
Air.'' And basically describes just how difficult it is going 
to be and address the challenges at hand. But there are some 
real opportunities, for example, reinventing the car so that it 
runs ultimately on hydrogen, let us say, or batteries, or 
something that doesn't emit CO2. What an exciting 
opportunity for us to make money, which is great thing too, and 
to clean the air, and to improve the national security of the 
United States. But it is going to be hard.
    I think we made progress here, today, Mr. Chairman, with 
the Speaker's open-mindedness to looking at nuclear power. That 
is a very significant development here today, I think. And it 
shows a level of cooperation I think we all need to have: come 
with open minds about how to solve this challenge.
    Part of the change in my thinking came from a wonderful 
trip to Antarctica about this time last year with a number of 
Members who are here today, led by Sherwood Boehlert, and 
perhaps one of you can help me relearn what I think I learned 
there about the methodology of the ice cores, the drillings, 
and what we found there. Can somebody describe that so I can 
relearn, and maybe, I can just learn?
    Dr. Alley. Happily. I have worked on ice cores in many 
places, Antarctica and Greenland, and essentially an ice core 
is like a really fancy drill. If you were going to put a knob 
in your door, you would just take a pipe with teeth on the end, 
you would spin it, you would run it down, you pull out a piece 
of ice, and you would do that until you have two miles of it. 
And if you break the bubbles, that is a little bottled sample 
of old air. You can find out whether carbon dioxide was higher 
or lower in the past. Very high confidence that this works. It 
matches the instrumental record over recent times, different 
cores from different places with different temperatures and 
different snowfall rates give the same answers. And so what 
shows is that the level of carbon dioxide, the level of 
greenhouse gasses that we have in the atmosphere, are 
unprecedented, at least for the last 650,000 years.
    Mr. Inglis. And going back to some earlier questions. What 
is the chance of that happening as a result of natural 
phenomena, that significant increase?
    Dr. Alley. If one looks at a long record like that and 
says, well, it surely looks now like we are above what nature 
has done for the last 650,000 years, and it happened in the 
last 1000, that would seem unlikely. In addition, we very 
clearly--oil companies are quite good; they know how to find 
oil. Coal companies are quite good; they know how to find coal. 
And we know how much they found, so we know how much is being 
burned. We know how much carbon dioxide is going into the air, 
and we know where it is going, and sort of our fingerprint is 
on this with very high confidence.
    Mr. Inglis. For those who dispute that, what is their best 
argument? Where can they find some data besides what you just 
reported on?
    Dr. Alley. I truly don't know what a really good argument 
is against this. There are a number--we have the budget. We 
know what is going up, what is going down. But then you can 
ask, well, is there evidence of that? Maybe your budgeting is 
wrong. And then you say--but carbon isotopic composition of 
fossil fuels is different than the carbon isotopic composition 
that was in the air. And we can see the change over time as 
humans are putting fossil fuel CO2 up. That applies 
both to the stable carbon and to the radioactive carbon. We are 
diluting the natural radiocarbon in the atmosphere by putting 
old carbon up from below. One can see the very, very tiny 
change in oxygen composition that goes with burning the fossil 
fuels. So once you say, well, we know the budget, then, someone 
will say, well, are you are right about that. Then, you say, 
well, if we are right, then you should say this in the stable 
carbon, you should see that in the radioactive carbon, you 
should see the others in the oxygen, and you see all of those.
    Chairman Gordon. The gentleman's time has expired. The 
Gentleman from Kentucky.
    Mr. Inglis. Mr. Chairman, a reminder to insert that in the 
record, the Samuelson piece, without objection?
    Chairman Gordon. Without objection.
    [The information follows:]
                       Information for the Record

                       Global Warming and Hot Air

                         By Robert J. Samuelson
                            Washington Post
                    Wednesday, February 7, 2007; A17
    You could be excused for thinking that we'll soon do something 
serious about global warming. Last Friday, the Intergovernmental Panel 
on Climate Change (IPCC)--an international group of scientists--
concluded that, to a 90 percent probability, human activity is warming 
the Earth. Earlier, Democratic congressional leaders made global 
warming legislation a top priority; and 10 big U.S. companies 
(including General Electric and DuPont) endorsed federal regulation. 
Strong action seems at hand.
    Don't be fooled. The dirty secret about global warming is this: We 
have no solution. About 80 percent of the world's energy comes from 
fossil fuels (coal, oil, natural gas), the main sources of man-made 
greenhouse gases. Energy use sustains economic growth, which--in all 
modern societies--buttresses political and social stability. Until we 
can replace fossil fuels or find practical ways to capture their 
emissions, governments will not sanction the deep energy cuts that 
would truly affect global warming.
    Considering this reality, you should treat the pious exhortations 
to ``do something'' with skepticism, disbelief or contempt. These 
pronouncements are (take your pick) naive, self-interested, 
misinformed, stupid or dishonest. Politicians mainly want to be seen as 
reducing global warming. Companies want to polish their images and 
exploit markets created by new environmental regulations. As for 
editorialists and pundits, there's no explanation except superficiality 
or herd behavior.
    Anyone who honestly examines global energy trends must reach these 
harsh conclusions. In 2004, world emissions of carbon dioxide 
(CO2, the main greenhouse gas) totaled 26 billion metric 
tons. Under plausible economic and population assumptions, CO2 
emissions will grow to 40 billion tons by 2030, projects the 
International Energy Agency. About three-quarters of the increase is 
forecast to come from developing countries, two-fifths from China 
alone. The IEA expects China to pass the United States as the largest 
source of carbon dioxide by 2009.
    Poor countries won't sacrifice economic growth--lowering poverty, 
fostering political stability--to placate the rich world's global 
warming fears. Why should they? On a per-person basis, their carbon 
dioxide emissions are only about one-fifth the level of rich countries. 
In Africa, less than 40 percent of the population even has electricity.
    Nor will existing technologies, aggressively deployed, rescue us. 
The IEA studied an ``alternative scenario'' that simulated the effect 
of 1,400 policies to reduce fossil fuel use. Fuel economy for new U.S. 
vehicles was assumed to increase 30 percent by 2030; the global share 
of energy from ``renewables'' (solar, wind, hydropower, biomass) would 
quadruple, to eight percent. The result: by 2030, annual carbon dioxide 
emissions would rise 31 percent instead of 55 percent. The 
concentration levels of emissions in the atmosphere (which presumably 
cause warming) would rise.
    Since 1850, global temperatures have increased almost one degree 
Celsius. Sea level has risen about seven inches, though the connection 
is unclear. So far, global warming has been a change, not a calamity. 
The IPCC projects wide ranges for the next century: temperature 
increases from 1.1 degrees Celsius to 6.4 degrees; sea level rises from 
seven inches to almost two feet. People might easily adapt; or there 
might be costly disruptions (say, frequent flooding of coastal cities 
resulting from melting polar ice caps).
    I do not say we should do nothing, but we should not delude 
ourselves. In the United States, the favored remedy is ``cap and 
trade.'' It's environmental grandstanding--politicians pretending 
they're doing something.
    Companies would receive or buy quotas (``caps'') to emit carbon 
dioxide. To exceed the limits, they'd acquire some other company's 
unused quotas (``trade''). How simple. Just order companies to cut 
emissions. Businesses absorb all the costs.
    But in practice, no plausible ``cap and trade'' program would 
significantly curb global warming. To do that, quotas would have to be 
set so low as to shut down the economy. Or the cost of scarce quotas 
would skyrocket and be passed along to consumers through much higher 
energy prices. Neither outcome seems likely. Quotas would be lax. The 
program would be a regulatory burden with little benefit. It would also 
be a bonanza for lobbyists, lawyers and consultants, as industries and 
localities besieged Washington for exceptions and special treatment. 
Hello, influence-peddling and sleaze.
    What we really need is a more urgent program of research and 
development, focusing on nuclear power, electric batteries, alternative 
fuels and the capture of carbon dioxide. Naturally, there's no 
guarantee that socially acceptable and cost-competitive technologies 
will result. But without them, global warming is more or less on 
automatic pilot. Only new technologies would enable countries--rich and 
poor--to reconcile the immediate imperative of economic growth with the 
potential hazards of climate change.
    Meanwhile, we could temper our energy appetite. I've argued before 
for a high oil tax to prod Americans to buy more fuel-efficient 
vehicles. The main aim would be to limit insecure oil imports, but it 
would also check CO2 emissions. Similarly, we might be 
better off shifting some of the tax burden from wages and profits to a 
broader tax on energy or carbon. That would favor more fuel-efficient 
light bulbs, appliances and industrial processes.
    It's a debate we ought to have--but probably won't. Any realistic 
response would be costly, uncertain and no doubt unpopular. That's one 
truth too inconvenient for almost anyone to admit.

     2007 The Washington Post Company

    Mr. Inglis. Thank you, sir.
    Chairman Gordon. Mr. Chandler from Kentucky is recognized 
for five minutes.

                        Climate Change Scenarios

    Mr. Chandler. Thank you, Mr. Chairman. I do not need to be 
persuaded. I think I can see facts rather clearly when they are 
presented. I had the opportunity, along with the gentleman from 
South Carolina, to go on that Congressional Antarctic sojourn 
last year, and it was a truly eye-opening experience. We saw a 
lot and, I think, got a pretty clear picture of what the 
science--at least the science that people were working on down 
there--showed. One thing that is abundantly clear is what the 
graphs show in the last handful of years, and that is shocking, 
truly shocking, to see the change in terms of warmth in the 
atmosphere in a really surprisingly short period of time. And 
frankly, it is just hard for me to imagine that fossil fuels 
can be deposited in the Earth over hundreds of millions of 
years and can be released in the amounts that they have been 
released in, in a very short period of time, without having 
some dramatic effect on the atmosphere. It just goes against 
any sort of reasonable thinking.
    And I would like to know, can you give us any idea about 
how quickly you feel this process is going to speed up in the 
near-term, this warming process? It has been quite dramatic in 
the last decade or two. Do you look for that speed, that sort 
of dramatic uptake to continue in the next couple of years? Do 
you think it will speed up exponentially?
    Dr. Meehl. Well, I think what we have seen from the 
scenarios we have run with the models is that pretty much no 
matter scenario we are on, the next 20 or 30 years, the warming 
is going to be about two-tenths of a degree centigrade, per 
decade. And of course, that is barring any huge volcanic 
eruption that would cool it down for a year or two. But from 
the anthropogenic or human-caused part, we are on a track now 
for another, for about two-tenth of a degree C warming over the 
next few decades. But having said that, when you get past about 
the 20s, 30s, then you will start seeing the scenarios really 
starting to spread.
    Mr. Chandler. You mean a big spike?
    Dr. Meehl. A spreading out. The high emissions give you 
more warming and the low emissions give you less warming. So we 
kind of have this very consistent warming no matter what 
scenario we are on for the next 30 years, and then you start 
seeing the spread. But having said that, it does make a 
difference what track we are on because we are setting 
ourselves on a course now to follow one of these outcomes and 
depending on if we are on a high-emissions outcome, we are 
going to get a lot more warming. If we are on a low-emissions 
outcome, we are going to get less warming. So I think what we 
do now does make a difference for the future.

                     More Climate Change Scenarios

    Mr. Chandler. Now, I would like to ask a question about the 
ice. Dr Alley, you have mentioned something on ice sheets being 
boring. The same, certainly, cannot be said about you. I can't 
help but ask, what do you think is going to happen? I heard 
predictions of dire results in the Arctic, among other places, 
largely because, as I understand it, because there is no land 
up there, and that makes a big difference in all of the forces 
that are involved there. Can you make some kind of a prediction 
about what you think is going to happen to the Arctic and how 
quick you feel that result will occur if we do nothing?
    Dr. Alley. There are a number of assessed-model results in 
the report looking at the sea ice of the Arctic Ocean, which is 
the frozen ocean water, and I don't have the quota in front of 
me, but some of the extreme warming scenarios in some of the 
models get to a no-sea-ice in the summer in the Arctic at the 
end of this century, so fairly large changes showing up in the 
frozen ocean water.
    Mr. Chandler. All gone?
    Dr. Alley. For the late summer, in the more extreme warming 
scenarios, in some of the models, and it would grow back in the 
winter in those models. So that is the floating part. Then, the 
part that is not yet floating, up on Greenland, almost 
certainly is there yet in the end of the century, but in the 
larger warming is melting fairly rapidly at that point.
    Mr. Chandler. Which would almost certainly have an impact 
on things like the Gulf Stream. A kind of huge impact, wouldn't 
it?
    Dr. Meehl. Not so much on the Gulf Stream. I think it is 
more on sea level raise. Because in the projections, where 
models have included melt from the Greenland ice sheet, like I 
was explaining before, it does contribute to slowing down this 
overturning circulation, but it doesn't ever actually stop it. 
But I think the biggest concern, and something Dr. Alley 
alluded to, is how unstable something like the Greenland ice 
sheet is. And this again is in this category as we are moving 
into an era where we are starting to observe things we have 
never seen before in recorded human history. Glaciologists have 
talked about the possibility of rapid ice-sheet destabilization 
as a possibility. They have talked about a possible mechanism. 
In the last ten years, they started to make observations that 
maybe this mechanism actually is working. But because we have a 
very short time period when we have actually observed this kind 
of possible instability, we don't know what to make of it. Like 
Dr. Alley said, is it a temporary thing? Would it be sustained 
or accelerated more in the future? And we just don't know. And 
I think that falls under the category of things that we can 
with certainty and other things that we just don't know about 
right now. This is obviously being researched, and a lot of 
scrutiny is being put on this now, so we will have better 
answers in the next few years, but right now, we just don't 
know.
    Chairman Gordon. The gentleman's time has expired, but I 
would assume that there is no good news. It is only bad news 
that will be coming from this. The Gentleman from Florida?

                          Scientific Consensus

    Mr. Diaz-Balart. Thank you, Mr. Chairman. First, I want to 
thank you for putting this hearing together. I think you 
brought some great witnesses. I also want to thank the Speaker. 
It is always good to bring attention to issues, so obviously, 
she honored us this morning.
    You know, I am pretty much like Mr. Inglis is, like 
Congressman Inglis. I have gone from not knowing much about it, 
just because you know, you see Hollywood movies, and that kind 
of scares me. The more you read--and being one that always has 
to--I think we all have to--obviously, since we aren't all 
scientists, we have to rely on the real science as much as 
possible, so what I keep hearing more of is that that is where 
real science is certainly going.
    I am asking for some reassurance to make sure that I am 
leaning in the right direction. I tell you that before, for 
example, the more I read--let me just quote this one thing from 
the press, ``As for the present trend, a number of leading 
climatologists have concluded that it is very unpleasant news, 
indeed.'' They say that it is the root cause of a lot of the 
unpleasant weather around the world, and they warn that it 
carries potential for human disasters of unprecedented 
magnitude. I keep hearing about this possibility because of 
global warming.
    What scares me sometimes is that that is not about global 
warming. That is an article in Fortune magazine from 1974 about 
climatologists now blame those droughts and floods on global 
cooling trends. I also have, then, from the Washington, January 
1970. ``Is mankind manufacturing a new Ice Age for itself?'' 
And it quotes a number of prestigious scientists who, now, are 
some of the ones who believe that they were wrong then and now 
that we are going to global warming. ``Winter held dawn of new 
Ice Age,'' this is from the Washington Post. Science Digest, 
``Brace yourself for an Ice Age.''
    If we would have obviously gone ahead and acted because of 
what a number of very prestigious scientists would have said 
then, we would have been dead wrong--because I have to believe 
you all. I really do. I happen to believe you all. So what I am 
asking for is reassure me that in 1970 we were still looking at 
science that the world was flat and that prestigious scientists 
were dead wrong, because that is what I believe because that is 
what I hear. And now science has changed dramatically and 
technology, which is what I think I have heard today--and that 
therefore that is wrong, and that the new consensus that we are 
in a warming trend is correct, and that therefore I can feel 
comfortable with that point of view.
    Dr. Alley. I will try first, and then maybe my colleagues 
will help a little bit.
    Mr. Diaz-Balart. And if I may interrupt you, Mr. Alley, I 
am also resentful of the fact that you made me very hungry this 
morning with your pancake analogies. It is 12:30, and I think 
that is unfair.
    Dr. Alley. I apologize for that, yes. We are with you on 
that one, actually.
    As scientists, you know, our job is to push the limits. I 
teach at a very large school, and I can assure you that there 
are a lot of very bright students there that are pushing the 
limits. They are coming up with new ideas that are going to 
help us and save us, and some of it is totally off the wall. 
And so as scientists, we bubble up all of these interesting 
ideas, and then you have built mechanisms, we have built 
mechanisms, the world has built mechanisms, to distill all of 
these ideas into something which is policy-relevant for you. 
And so this global cooling, which some of it came from us 
learning to understand the Ice Age, and some it came from a lot 
of aerosols coming out off smokestacks, blocking the sun, was 
something that was bubbled up in a little bit of discussion and 
huge amount of press interest. But if you go back and ask if 
the National Academy actually come out with a global-cooling 
warning, you won't find it. You know, when you get to the point 
of asking was the assessed knowledge that was pulled together 
policy relevant for you? Was that warning about this? Was that 
the big issue? I don't believe you will find it. And so the 
IPCC here exists as a mechanism, as does the National Academy. 
It exists as a mechanism to take all of these wonderful ideas, 
this ferment and froth that is out there in the scientist 
community, and say what stands up, what is reliable, and to 
give it to you. And we are here to tell you that the assessed 
science of the world is pointing to human activities, changing 
the atmosphere in a way that is causing warming.
    Mr. Diaz-Balart. And I appreciate that.
    Mr. Gilchrest. Will the gentleman from Florida yield just 
for two seconds on this time?
    Mr. Diaz-Balart. Of course.
    Mr. Gilchrest. Having lived through that period of time, 
and having read a number of articles and books, born in the 
1970s, Dr. Alley is correct, there was not a consensus that we 
were cooling. There was some suggestion, for a variety of 
reasons--the consensus was are we cooling or warming. We don't 
know yet. So at that point, there was no consensus.
    Chairman Gordon. The gentleman's time has expired.
    Mr. Diaz-Balart. Could I have a ten-second comment?
    Chairman Gordon. With unanimous--we will see if I can get 
this unanimous consent. I wasn't able to get one earlier.
    Mr. Diaz-Balart. Mr. Chairman, I just learned--is it 
possible that the press exaggerates on issues? I am just 
shocked at what I learned today in this committee. I can't 
believe that. I am sorry. I just can't believe that.
    Chairman Gordon. Okay. Thank you, Professor--or Doctor, was 
it? I guess it was Inspector Reneau. And a very patient 
gentlelady from Arizona, Ms. Giffords, is recognized for five 
minutes and ten seconds extra if she needs it.

                Impact on the Southwestern United States

    Ms. Giffords. Thank you Mr. Chairman. First of all, I want 
to thank all of you for coming. It is important that you are 
here. We appreciate that you are here. The American people are 
glad you are here, and frankly, the world is. This is an area 
that I so passionately believe that we need to lead in. And I 
look around at all of the portraits behind you, particularly 
that depict America's mission to go to the Moon and to explore 
space and where we lead. And that Apollo mission of the future, 
I believe, is in energy and climate change. And this is just a 
first start. Mr. Chairman, thank you for bringing such 
distinguished speakers here today, and we appreciate your 
science. We may all not agree, but this is a process where we 
deliberate, and I just certainly appreciate being here.
    My question reflects my district, which is Southern 
Arizona, the most extraordinary district. If you can, imagine 
Tucson going all of the way to New Mexico. And this is an 
area--we are not sure quite, but eight or nine years of a 
drought we are experiencing. We are also seeing some other 
strange changes that we have just not seen before. We had a 
very strange storm happen about a year-and-a-half ago that 
produced some rockslides in our mountains that we are not 
familiar with. We also had some wildfires in Arizona, 
particularly in the Catalina mountain range, that burned very 
hot, we understand, that because of the weevil infestation that 
has been allowed to build up, because of it not freezing, and 
the trees then weakening. So I am just curious and as a former 
legislator, I tried to establish a climate-change study group 
in the Arizona legislature. We brought some distinguished 
scientists from the University of Arizona, where they have a 
global climate center, and frankly, my colleagues on both sides 
of the aisle were not polite to the scientists. And even one of 
my colleagues said well, heck, hot is hot. What is the 
difference between 115 degrees or 120 degrees? So I ask you, 
and I am not sure which scientist to address this to, if you 
could explain in real terms, for the citizens of southern 
Arizona, the difference between 115, 116 degrees, 120 degrees. 
What does that really mean in the next five years, the ten 
years, and 50 years for the people of Arizona?
    Dr. Trenberth. Well, let me have a crack at this there.
    Indeed, the drought in the southwestern parts of the United 
States from 1999 to 2004 is one of the things which we think 
may be, indeed, symptomatic of the climate changes that are 
underway related to global warming. In the winter of 2004-2005, 
we had weak to moderate El Nino, so there was maybe temporary 
relief. We are not quite sure. Certainly, the droughty regions 
have continued since then. But your concern about temperature, 
there are a number of analogs, and perhaps one of the best 
analogs is the year 2002 which is when the drought in the West 
and in the Southwest was most extensive. And one of the things 
that goes along with the drought is higher temperatures and 
heat waves, and in particular, one of the consequences is 
wildfires. And the risk of wildfires went up in 2002, there 
were a very large number of wildfires. In fact, I don't know 
what the cost of those was; I do know there was over a quarter 
of a billion dollars spent just in fighting the wildfires 
alone. And so that is one of the risks that goes along with the 
increases in drought and increases in heat waves.
    Dr. Meehl. Let me just add that the Southwest U.S. is 
actually an area that we saw some interesting results when we 
looked the model projections for extreme events, and you 
mentioned rainfall. That's an area that shows that when it does 
rain, in future projections, it rains harder, but there are 
actually more days in between rainfall events. So the dry 
spells in between rainfall events increases, but when it does 
rain, it rains really hard. But when you average those changes 
over a season, the average rainfall is still less in the future 
projection. So in that area, in the Southwestern U.S., is one 
area that is most consistent for this kind of result where you 
just see a change in the nature of the precipitation, how it 
falls, and how intense it is when it does rain.

                      Regional vs. Global Modeling

    Ms. Giffords. Dr. Meehl, if I can follow up with you 
concerning the difference between regional modeling and global 
modeling. Can you talk a little bit about the regional models 
and how long it is going to take them to catch up, globally?
    Dr. Meehl. Yes, there is whole class of models that we can 
imbed, various high resolution regional models in the global 
models, so we have better representation of the mountain ranges 
and things like that. This can be very important in regions 
where, like in Colorado where I am from, where you have big 
mountains, or in Arizona, you see the mountain ranges and where 
you get almost locally specific rainfall regimes depending on 
how the mountain ranges are. We can imbed these models in the 
global models and get more information on smaller space scales. 
But those regional models really depend on good global models 
to drive them. And it is kind of the old garbage-in, garbage-
out adage for computing. So if your global model is bad, your 
regional model is not going to do much better. But if the 
global model is improved it can drive the imbedded regional 
model in a more credible way. So that is one of the tools that 
we can use to get more regionally specific climate-change 
information, but it is still just a tool. It is not an end in 
itself.
    Chairman Gordon. The lady's time has expired. I will say 
that my grandfather used to tell me that the most important 
road in the county is the one in front of your house. You have 
learned that lesson also.
    Ms. Giffords. And Mr. Chairman, can I just say that if 
every kid growing up had Dr. Alley as a science teacher, we 
would have more kids going into science because of your 
passions, so thank you, Dr. Alley.
    Chairman Gordon. So that is why we all want to sponsor and 
be part of our competitiveness agenda. We are going to do that 
with more scholarships for more science and math and physical 
science teachers.
    Again, the patient gentleman from Georgia, Mr. Gingrey, 
thank you for sticking with us.

              U.S. Leadership in Mitigating Climate Change

    Mr. Gingrey. Mr. Chairman, thank you so much. It has not 
been difficult sticking with you for almost three hours. I am, 
as you know, returning to the Science Committee, and so it puts 
me down in the bottom row.
    But Dr. Alley, you had commented that those ice sheets are 
sometimes--well, most of the time are boring and are 
occasionally exciting, and I think you might could say the same 
thing about the Science Committee, those of you have been here 
this morning. And I think under Chairman Gordon's leadership, 
it is going to be mostly exciting on the Science Committee. I 
agree with my colleague who just said in complimenting Dr. 
Alley and the other panelists who testified on the panel this 
morning. If you could take the tape of this hearing and play it 
to the middle school class, I guarantee there would be more 
young people going into science because this has indeed been 
very exciting.
    Chairman, I think you said there wasn't a lot of good news 
here. I would say that although it is pretty frightening, the 
global warming and the sea level and the ultimate outcome of 
what that might be, well, the good news is it looks like God 
has given us a lot more time than he gave Noah. Now, Dr. 
Solomon, that is not your NOAA. That is N-o-a-h.
    I wanted to point out, and it is been said by some of my 
colleagues, that a number of us, actually six on this 
committee, had an opportunity to go to Antarctica, and that is 
because of the Science Committee. And I was one of those six, I 
am very grateful. And it was mentioned today, something, a 
policy, that when we were on the ice, that we couldn't use 
aerosols. I now know why. I didn't ask the questions, then. But 
this has been an outstanding hearing. I am grateful to the 
panel. I am grateful for the Speaker. It is an historic 
opportunity for the Speaker of House to come before the 
Committee and testify. I appreciate her comments, particularly 
in regard to nuclear power. I do have an answer for one of her 
concerns and that is where would we store the waste? I would 
suggest that maybe there is place out in Nevada called Yucca 
Mountain, but that is an argument for another day.
    I do have a question, believe it or not, and Dr. Meehl, I 
am going to address it to you. There is going to be an upcoming 
article in Newsweek magazine by George Will. We have talked 
about this, and I know this is a question that you scientists 
maybe don't want to address and are maybe not necessarily the 
experts, and that is for us to do, but basically this is what 
he says in this article ``Inconvenient Kyoto Truth: the United 
States is able to drastically regulate our manmade, greenhouse 
gas emissions,'' 35 percent, as was stated by Dr. Ehlers, ``but 
other large industrial countries like China, Israel and Brazil, 
do not.'' Will the United States efforts still achieve a 
positive effect? Take, for example, that China is set to 
construct all of those new coal-powered plants by 2030, and 
they have stated that they have no interest, they aren't going 
to do anything to regulate their emissions. What will the 
United States' restrictions do to stem the climate change 
trends that you outline in the IPCC AR-4 report? And that is my 
question.
    Dr. Meehl. And again, I am going to have to apologize 
because I am not an expert in this area, so I really can't give 
you a good answer for that.
    Mr. Gingrey. Well, any one of the four would be grateful.
    Dr. Trenberth. It will set a good example. I mean I think I 
think it is a global problem, and U.S. leadership plays a key 
role, and it does relate then to international pressures to 
bring everyone in line, I think.
    Mr. Gingrey. Anyone else? Dr. Trenberth, I think that is a 
darn good answer, and I appreciate it, and I too have learned a 
lot here today and changed my attitude. I began to change that 
attitude when I went to the ice about a year ago, and that was 
a great opportunity. I thank you, Mr. Chairman, and I yield 
back.
    Chairman Gordon. Thank you, Dr. Gingrey. In response to 
your suggestion that we should be able to watch this for 
children, we can. Compliments of the Science Committee, if you 
will go to www.science.house.gov, you can get the web cast of 
this hearing, the witnesses' statements, Leader Pelosi's 
statement, and the Chair and Ranking Member's statement, so 
that is, once again--get your pencil--www.science.house.gov.
    I was two out of three today, Mr. Gilchrest, on unanimous 
consent. The first unanimous consent was to allow you as a 
former Member of this committee to sit in and ask questions, so 
we will conclude with those statements or questions with you, 
sir.

                        More on Climate Science

    Mr. Gilchrest. Thank you very much, Mr. Chairman. I am very 
happy to see that none of my Republican colleagues objected to 
that. I have been on the Science Committee a couple of times in 
the past, and like many of my colleagues, I have been to the 
ice, the dry valleys and the magnificent spots down there in 
the Antarctica, so maybe after this hearing, I might ask my 
side for a waiver to get on the Science Committee again. It 
looks like it is going to be a pretty exciting year.
    I want to take a few seconds to talk about the economic 
impact of pursuing a program to reduce greenhouse gases and 
what that would do. To my colleagues remaining here, we have 
worked with about a dozen Fortune 500 companies, including 
DuPont, General Electric, Caterpillar, Lehman Brothers, and so 
on to work this issue through. Their suggestion, their strong 
suggestion, is based on the risk factor of investment of doing 
something and what could happen economically if we don't do 
something. Their suggestion is that the Federal Government 
create a goal of reducing greenhouse gases by the year 2050 by 
70 percent below 1990 levels and then set up a regulatory 
structure in which there is a cap-and-trade program and tax 
incentives. And they say through that structure, they can meet 
that goal by the year 2050--not only meet that goal, but excel 
at it based on propensity and ingenuity of the United States 
technology and efficiency, and improve economic viability by 
improving situations as far as dependence on foreign oil is 
concerned and a whole range of other things. So there is a 
pretty good structure out there to do that.
    I have four questions that I would like to ask right up 
front in case I run out of time. The first one is, you have 
mentioned, let us say, 10,000 years ago that CO2 
concentrations in the atmosphere was about 180 parts per 
million. Fast forward about 10,000 years, and you have it at 
280 per million. And then you come up to the present day, and 
it is about 380 parts per million. Now, the most recent 
introduction of increases from a variety of sources is the 
burning of fossil fuel. Like one of our colleagues said, we 
have put in the atmosphere in just a few decades, that it took 
the natural sources to lock up in the form of fossil fuel over 
millions of years. Can you make a distinction between the kind 
of carbon that you get from a volcano or other natural sources 
and the kind of carbon that you get from burning fossil fuel? 
Is there a marker that you can see, and do you use that in your 
equation to determine what it man-induced and what not man-
induced?
    The second question is can you over, let us say, the last 
20 years, maybe the last 30 years, determine the cubic miles, 
the volume of water, coming off the Greenland ices, and has 
that accelerated in the last 20, 10, five years.
    Chairman Gordon. In all due respect, let us see if we are 
going to have time to get through those two before we go on any 
further.
    Dr. Solomon. On the first one, if I may, the numbers you 
gave were more or less right, except for the time scales. The 
time when very much lower concentration of CO2 were 
observed is really quite a bit earlier. You have to go back to, 
really, the ice ages.
    Mr. Gilchrest. About 10,000 what were the concentrations?
    Dr. Solomon. You have to go a little bit farther back, more 
like 20.
    Mr. Gilchrest. 20,000, it was about 180 parts per million.
    Dr. Solomon. And then when we came out of the Ice Age, it 
went to about 270. As it said earlier, it stayed at 270 for 
almost 9.9 thousand years.
    Mr. Gilchrest. Really, that is even more incredible.
    Dr. Solomon. Yeah, you can see that in Figure 1. And then, 
in the last 100, it went dramatically up to about 380, which is 
where it is now, and it has not been at levels that high in at 
least 650,000 as Dr. Alley said.
    Your question about a marker is also a very good one. As we 
talked about earlier, the kind of carbon that you get when you 
burn a fossil fuel is different in terms of its isotopes than 
what you get from, you know, say trees or other sources of 
carbon. So the changes in isotopes are a very key element in 
demonstrating the human influence. Also, the north-south 
gradient, we see a difference between the northern hemisphere 
and the southern hemisphere which is also indicative of the 
human source in the northern hemisphere.
    Dr. Alley. And then for the Greenland ice sheet, we have 
watched some of the glaciers speed up with satellite data and 
put more icebergs into the ocean, and the Atmospheric Surface 
Mass Balance Community has been reconstructing snowfall and 
melting on the ice sheet and has seen a rise in snowfall but a 
faster rise in melting so that it is losing mass that way. You 
also see that from satellite.
    Chairman Gordon. Excuse me. The gentleman's time has 
expired. In respect to this committee, this panel has been here 
for three hours. I know you have another briefing to go to and 
then you have a hearing in the Senate. The Minority had more 
than due notice to find someone to rebut you. They were not 
able to do that either through the scientific community or 
through the Chamber of Commerce. However, Mr. Rohrabacher has 
been very studious these last three hours in preparing a 
rebuttal, and I think it is only fair that we allow him that 
opportunity.
    Mr. Rohrabacher. Thank you much, Mr. Chairman. First, of 
all, let me compliment you on putting together a fine panel of 
experts for us, and I apologize for us in the Science Committee 
along with the many scientists, who disagree with them and have 
honest disagreement on this issue. And in fact, I will be 
placing in the record the names of hundreds of those scientists 
who disagree with this concept that climate change is caused by 
human activities. Not that there is climate change, but that it 
is caused by human activity. And we could have had any number 
of those scientists, and it was remiss on our part not to have 
someone here representing a scientific--there are people from 
MIT and Harvard and many, many respected scientists who 
disagree with this theory. They should have been here. It is 
our fault for not getting them here.
    Let me compliment you as far as a good panel. I think it is 
great that Speaker Pelosi was here, and I apologize if I do not 
believe that the objection that was made reflects in any way 
the attitude of the other Members of this committee, the 
Republican Members of this committee. I thought it was fine 
that she spoke, and we paid her the same respect that paid Newt 
Gingrich and others who have spoken before this panel in the 
past.
    With that said, I do have very serious disagreement with 
some of the ideas presented today. And look, the reason I have 
to push for an answer, and I shouldn't have to actually ask 
five times before I get an answer on certain questions, that it 
is important to know how much of the greenhouse gases that 
exist in our atmosphere were caused by natural occurrences. And 
that is an important thing because in terms of the weight that 
you put on the changes that need to be made it makes all of the 
difference in the world. A small change--and if you believe 
that, as I do, and I remember Dr. Bartlett, who is also a Ph.D. 
I might add, and has many credentials on this, nor did he 
believe was 10 percent. Vern Ehlers said 35. I have heard other 
science panels who really struggled to say that it was between 
five and ten percent. With that noted, there is a huge 
disproportion of natural causes of greenhouse gas. Which means 
that a small change in the natural causes of greenhouse gases, 
like volcanoes, would have a much bigger impact than a change 
of human activity, if we could, indeed, create human-activity 
change on such a broad scale.
    So scientists disagree. I am submitting for the record 
their names. Also, let me note that many scientists are 
complaining that their research money has been cut off because 
they disagreed with global warming concepts, and I will be 
submitting their names for the record as well.
    But there is no doubt that global climate change is 
happening. The only question is why is this cycle of global 
climate change, and we have gone through dozen of cycles of 
global climate change, why is it any different than all the 
other cycles? I noted during the testimony that was presented, 
the chart that shows that we are now in a cycle when 
temperature is going up, that it started at the very end of the 
mini Ice Age which was a very low point, where temperature had 
been declining for hundreds of years. So whether or not how 
dramatic this change will be or what it is caused by, are 
things that honest people, I think, can disagree with. And I 
really, personally, having been a journalist, the first thing I 
was cautioned by is when someone was claiming, ``well everybody 
is on my side or everybody says this or there is a total 
consensus.'' Most always when people said that to me during my 
years as a journalist, it wasn't true. It was that there were 
honest people who disagreed and there was significant 
disagreement on such issues, and we don't know what those other 
cycles were caused by in the past. It could be dinosaur 
flatulence or--who knows? But we do know the CO2 in 
the past had its time when it was greater as well. And what 
happened when the CO2 was greater than now? There is 
been many cycles of up-and-down warming.
    So with that said, I think that we have had a great 
discussion today. We need this discussion because the idea, Mr. 
Chairman, of having some sort of initiative so that our country 
creates new energy sources to make ourselves independent and 
making sure that those energy sources are clean is a totally 
bipartisan goal. It is. There is no doubt that all of us should 
want to make sure that America isn't held hostage to foreign 
energy sources and that when we do develop new energy sources 
that they are clean. But the question that comes to the heart 
of the matter is this--I am sorry for pontificating too long in 
this--when we make that decision as a Congress as to what those 
energy alternatives will be, we shouldn't be basing on science, 
if it is wrong science that suggests that global climate change 
is as big an issue as human health. I would prefer to make sure 
that when we are becoming energy independent and that we 
develop new energy sources, that we focus our science on making 
sure that we take the bad stuff out of the atmosphere that 
hurts human beings, rather than the stuff that may or may not 
create a cycle that would make us two or three degrees warmer 
or less in the future.
    So with that, I have had my say. I appreciate the privilege 
of having a closing statement. I appreciate your leadership on 
this. You held a great discussion today.
    Chairman Gordon. Thank you, Mr. Rohrabacher. I hope you 
feel better. I think the panel has addressed Mr. Rohrabacher's 
concern on a variety of occasions, so I won't take your time 
any more, but I do want to very sincerely thank you for the 
Herculean effort that you put into this product and for 
allowing the United States Congress Science and Technology 
Committee to be your first forum today
    I think one of the lessons learned today is something that 
we all should already know which is sometimes it is tough to be 
a messenger, but you have a very important message. We are glad 
you came. The message that needs to go out from this hearing is 
that 113 nations concurred, including this country, that with 
100 percent certainty, there is global warming and with 90 
percent certainty it is a result, to a great extent, from human 
activities.
    Thank you very much for being here, and all of the 
witnesses are dismissed, and the meeting is adjourned.
    [Whereupon, at 1:05 p.m., the Committee was adjourned.]
                               Appendix:

                              ----------                              


                   Answers to Post-Hearing Questions




                   Answers to Post-Hearing Questions
Responses by Susan Solomon, Co-Chair, IPCC, Working Group I: The 
        Physical Basis of Climate Change; Senior Scientist, Earth 
        System Research Laboratory, Office of Oceanic and Atmospheric 
        Research, National Oceanic and Atmospheric Administration, U.S. 
        Department of Commerce

Questions submitted by Representative Ralph M. Hall

Q1.  How did you develop the Summary for Policy-makers? For example, 
did you ask policy-makers what scientific information would be most 
useful to them and structure the Summary around that information? If 
not, how did you determine which findings to include in the Summary for 
Policy-makers?

A1. First and subsequent drafts of the Summary for Policy-makers (SPM) 
were prepared and revised by a sub-group of authors of the IPCC (2007) 
Working Group I Report and reflect their joint selection of material 
that they felt should be presented in order to best summarize the full 
report.
    The list of those scientists is given on the front page of the 
Summary and includes 33 primary authors (collectively representing each 
of the 11 chapters of the full report), along with 18 contributing 
authors.
    Drafts of the SPM were also discussed with the entire Working Group 
I author team during author team meetings. All of the 152 authors of 
the full report were also invited to provide written comments. Comments 
were also invited from over 600 experts who had reviewed the rest of 
the full report. Comments were also invited from governments. The SPM 
draft was revised by the listed subgroup of authors based upon their 
evaluation of all comments received.
    In the course of the IPCC Working Group I Tenth Session held in 
Paris from January 29 to February 1, 2007, delegates from 113 countries 
approved the final SPM on a line-by-line basis. Authors were present 
throughout this session and were charged with ensuring that all 
proposed changes to wording in the SPM remained fully consistent with 
the full report. During this final approval process the Lead Authors 
also identified a small number of changes to the underlying report that 
will ensure consistency with the language used in the final SPM or 
provide additional clarity for policy-makers on matters discussed 
during the session. None of these changes alter the substantive 
findings of the report and the list of such changes was made available 
from the IPCC Working Group I web site after the conclusion of the WG I 
session (http://ipcc-wg1.ucar.edu/).

Q2.  It is my understanding that in this IPCC report you associated 
terms such as ``very likely'' with numerical confidence levels such as 
``90 percent probability of occurrence;'' but that in previous IPCC 
reports you did not associate numerical confidence levels with terms 
such as ``very likely.'' Why did you add in the numerical confidence 
levels in this IPCC report?

A2. Addressed in joint response.
                   Answers to Post-Hearing Questions
Responses jointly by Richard B. Alley, Lead Author, IPCC, Working Group 
        I, Chapter 4: Observations: Changes in Snow, Ice and Frozen 
        Ground; Evan Pugh Professor of Geosciences and Associate of the 
        Earth and Environmental Systems Institute, Pennsylvania State 
        University; Kevin E. Trenberth, Coordinating Lead Author, IPCC, 
        Working Group I, Chapter 3: Observations: Surface and 
        Atmospheric Climate Change; Head, Climate Analysis Section, 
        National Center for Atmospheric Research; Gerald A. Meehl, 
        Coordinating Lead Author, IPCC, Working Group I, Chapter 10: 
        Global Climate Projections; Senior Scientist, National Center 
        for Atmospheric Research; and Susan Solomon, Co-Chair, IPCC, 
        Working Group I: The Physical Basis of Climate Change; Senior 
        Scientist, Earth System Research Laboratory, Office of Oceanic 
        and Atmospheric Research, National Oceanic and Atmospheric 
        Administration, U.S. Department of Commerce

Question submitted by Representative Ralph M. Hall

Q1.  It is my understanding that in this IPCC report you associated 
terms such as ``very likely'' with numerical confidence levels such as 
``90 percent probability of occurrence;'' but that in previous IPCC 
reports you did not associate numerical confidence levels with terms 
such as ``very likely.'' Why did you add in the numerical confidence 
levels in this IPCC report?

A1. It is not the case that numerical confidence levels were introduced 
for the first time in this report as suggested in the question. IPCC 
has carefully developed the numerical confidence levels used, and they 
were also used in the previous IPCC report in 2001 (see footnote 7 of 
the 2001 Summary for Policy-makers, page 2 of the report). The terms 
``likely'' and ``very likely'' were used in the 2001 report where each 
was deemed appropriate by the authors, and the terms ``likely'' and 
``very likely'' are used in exactly the same way in the new IPCC (2007) 
report. This was introduced in the 2001 report to avoid the problem 
that the confidence, uncertainty and likelihood of certain things can 
be interpreted differently by different readers of the report, so a 
clearly defined scale aids communication and understanding.

Questions submitted by Representative Jo Bonner

Q1.  A Wall Street Journal article dated Feb. 5, 2007 says that data 
from the U.S. National Climate Data Center showed that in 2006 the 
world was only 0.03 degrees Celsius warmer than it was in 2001. This 
difference is in the range of measurement error and is thus not 
statistically significant. This data might suggest that the world is 
not warming as fast as first thought. How do you respond to this data 
report?

A1. These data do not indicate any weakness in scientific observations 
of warming to date or projections of further temperature increase 
described in the Working Group I report. Natural fluctuations 
associated with weather and phenomena like El Nino mean that warming 
trends are only reliably seen over decades, not year to year. The 
recent history of temperature change includes a general warming trend, 
most of which is very likely due to the increase in greenhouse gas 
concentrations, overlaid with year-to-year variability arising from 
other features of the climate system. The effects of this short-term 
variability must be separated from the longer-term trend to allow 
estimation of the size of the trend; the comparison between single-year 
numbers for 2001 and 2006 does not do so, and so does not produce a 
scientifically valid estimation of the warming trend. Over the past 25 
years the trend is 0.18+C per decade, and the statistical 
uncertainty puts the value from 0.13 to 0.23+C per decade 
with 90 percent confidence.

Q2.  A report published by the Center for Science and Public Policy and 
authored by Lord Christopher Monckton shows that a 2001 U.N. assessment 
has over-estimated the human influence on climate change by at least 
one-third. Lord Monckton also says that in a 2001 report the U.N. 
estimated that sea levels would rise three feet by 2100, but in reality 
he notes that sea levels will rise only seventeen inches. This is a big 
difference. What do you think this difference shows?

A2. We presume that the reports referenced are the ``IPCC Fourth 
Assessment Report 2007: Analysis and Summary'' and the corresponding 
IPCC Third Assessment Report from 2001. Further, we presume that the 
claimed ``over-estimate'' of human influence refers to this statement 
in Lord Monckton's document: ``The U.N.'s 2001 report showed that our 
greenhouse gas emissions since 1750 had caused a ``radiative forcing'' 
of 2.43 watts per square meter. Our other effects on climate were shown 
as broadly self-canceling. In the current draft, the U.N. has cut its 
estimate of our net effect on climate by more than a third, to 1.6 
watts per square meter. It now thinks pollutant particles reflecting 
sunlight back to space have a very strong cooling effect.''
    The values in the 2007 IPCC report actually are very consistent 
with and thus increase confidence in those from the earlier IPCC 
report, and show that the previous report did not ``over-estimate the 
human influence on climate change by at least one-third.'' Primarily 
because of continuing emissions, the best estimate of radiative forcing 
of long-lived greenhouse gases has increased from 2.43 watts per square 
meter in the 2001 report to 2.64 watts per square meter in the 2007 
report (obtained by summing the central estimates of the effects from 
carbon dioxide, methane, nitrous oxide and halocarbons from Table SPM-2 
of the 2007 report, corresponding directly to the sum from the 2001 
report). This long-lived greenhouse gas forcing is not the total 
forcing, however, and the effects of ozone and the cooling effects of 
aerosols must be properly included. The 2001 report did discuss the 
aerosol effects (in Lord Monckton's words, the ``cooling effect'' of 
``pollutant particles''), including direct effects on radiation and 
indirect effects through induced changes in clouds, but the 2001 report 
noted that no best estimate could be given for some of these effects 
owing to large uncertainties. The improved ability to include these 
effects in the 2007 report represents a scientific advance that more 
accurately quantifies the human effect on climate, and does not in any 
way represent a prior overestimate of human influence.
    Regarding sea-level rise, the Summary for Policy-makers of the IPCC 
Fourth Assessment Report states (p. 14) that, if considered for the 
same time interval and emission scenario, the midpoint of the projected 
sea-level rise from the Third Assessment Report is within 10 percent of 
that for the Fourth Assessment Report, and that, had uncertainties been 
treated in the same way, the ranges in those projections would have 
been similar. Thus, there is not a big difference. Furthermore, as 
noted in our response to Question 5, below, any additional contribution 
to sea-level change from additional changes in the dynamical behavior 
of the large ice sheets cannot be assessed accurately and was therefore 
omitted from the quantitative estimates.

Q3.  Do you think that more emphasis needs to be placed on the 
population increases in China and India and the vast migration from 
rural areas to cities? This increase creates demand for property and 
increases pollution in the cities. Why do we not focus more on these 
areas to reduce pollution and stop what you consider global warming?

A3. Our testimony concerned the findings of Working Group I of the 
Fourth Assessment Report of the Intergovernmental Panel on Climate 
Change, on the physical science basis of climate change. Impacts and 
adaptation will be considered by Working Group II, and mitigation by 
Working Group III. The question here goes beyond the scope of our 
Working Group I report, and beyond our individual scientific expertise. 
However, different possible future population levels, patterns of 
development, and energy sources and conversion technologies, among 
other factors, are considered in the Special Report on Emissions 
Scenarios (SRES). The SRES scenarios in turn underlie the projections 
of future climate change discussed in the Working Group I report. The 
different scenarios, e.g., in Table SPM-2 and Figure SPM-7, therefore 
provide considerable information on the importance of the factors 
mentioned in the question.

Q4.  A.R. Ravishankara with the National Oceanic and Atmospheric 
Administration said that if you remove pollutants from the air that act 
as a cooling mechanism, then the heating effect would be intensified. 
How do you suggest that we find a medium to which pollutants could be 
reduced to an extent without harming the cooling effect that they have?

A4. Dr. Ravishankara's statement is fully consistent with the IPCC 
(2007) report. For a given atmospheric concentration of anthropogenic 
greenhouse gases, lowering the level of anthropogenic aerosols would 
produce an additional heating effect. (We interpret ``pollutants'' in 
the question to refer to anthropogenic aerosols.) As a corollary to 
this, the ``cooling'' effect of current levels of aerosols can be seen 
in estimates of global-average radiative forcing. As shown in Figure 
SPM-2 of the Summary for Policy-makers of the Fourth Assessment Report 
of Working Group I of the Intergovernmental Panel on Climate Change, 
there is a negative radiative forcing from anthropogenic aerosols, 
partially offsetting the warming effect of anthropogenic greenhouse 
gases.
    The appropriate policy response to this observation is beyond the 
scope of our report, and beyond our individual scientific expertise. 
Climate science and the Working Group I Report can inform policy 
choices by describing how the climate will respond to given levels of 
aerosols and greenhouse gases. However, there is nothing inherent to 
the Earth's physical climate that prevents both anthropogenic aerosols 
and anthropogenic greenhouse gases being reduced to whatever levels are 
deemed societally desirable. For instance, by increasing energy 
efficiency and cutting down on fossil fuel burning, both greenhouse gas 
and aerosol emissions could be reduced.

Q5.  The U.N. Climate Panel estimates that Antarctica will actually 
increase its snow mass this century. Would this not go against the 
argument that scientists are making saying that glaciers and polar ice 
caps are melting as a result of global warming?

A5. We presume that ``The U.N. Climate Panel'' refers to Working Group 
I of the Intergovernmental Panel on Climate Change, in which we 
participated. Our report notes that data show that mountain glaciers 
have declined on average in both hemispheres, and that losses from the 
ice sheets of Greenland and Antarctica have very likely contributed to 
sea level rise over 1993 to 2003. The report states ``Current global 
model studies project that the Antarctic ice sheet will remain too cold 
for widespread surface melting and is expected to gain in mass due to 
increased snowfall. However, net loss of ice mass could occur if 
dynamical ice discharge dominates the ice sheet mass balance'' (p. 17) 
and, with reference to the dynamical ice discharge, ``understanding of 
these effects is too limited to assess their likelihood or provide a 
best estimate or an upper bound for sea level rise.'' (p. 17) Thus, 
increased snowfall is expected in Antarctica, but the trend in overall 
mass of the ice sheet (including loss by ice flow feeding iceberg 
calving) is not known. More generally, all glaciers respond to the 
balance between accumulation of snow and loss by melting or iceberg 
calving. With warming, the atmosphere can hold more water vapor and 
thus precipitation is apt to increase. In some areas, a resulting 
increase in accumulation wins out. However, for most glaciers, in spite 
of increased accumulation, the melt wins out, but this can vary 
enormously over short distances depending on the local features.
          
          
          
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