[Senate Hearing 109-1111]
[From the U.S. Government Publishing Office]
S. Hrg. 109-1111
PROJECTED AND PAST EFFECTS
OF CLIMATE CHANGE: A FOCUS ON
MARINE AND TERRESTRIAL SYSTEMS
SUBCOMMITTEE ON GLOBAL CLIMATE CHANGE
COMMITTEE ON COMMERCE,
SCIENCE, AND TRANSPORTATION
UNITED STATES SENATE
ONE HUNDRED NINTH CONGRESS
APRIL 26, 2006
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SENATE COMMITTEE ON COMMERCE, SCIENCE, AND TRANSPORTATION
ONE HUNDRED NINTH CONGRESS
TED STEVENS, Alaska, Chairman
JOHN McCAIN, Arizona DANIEL K. INOUYE, Hawaii, Co-
CONRAD BURNS, Montana Chairman
TRENT LOTT, Mississippi JOHN D. ROCKEFELLER IV, West
KAY BAILEY HUTCHISON, Texas Virginia
OLYMPIA J. SNOWE, Maine JOHN F. KERRY, Massachusetts
GORDON H. SMITH, Oregon BYRON L. DORGAN, North Dakota
JOHN ENSIGN, Nevada BARBARA BOXER, California
GEORGE ALLEN, Virginia BILL NELSON, Florida
JOHN E. SUNUNU, New Hampshire MARIA CANTWELL, Washington
JIM DeMINT, South Carolina FRANK R. LAUTENBERG, New Jersey
DAVID VITTER, Louisiana E. BENJAMIN NELSON, Nebraska
MARK PRYOR, Arkansas
Lisa J. Sutherland, Republican Staff Director
Christine Drager Kurth, Republican Deputy Staff Director
Kenneth R. Nahigian, Republican Chief Counsel
Margaret L. Cummisky, Democratic Staff Director and Chief Counsel
Samuel E. Whitehorn, Democratic Deputy Staff Director and General
Lila Harper Helms, Democratic Policy Director
SUBCOMMITTEE ON GLOBAL CLIMATE CHANGE AND IMPACTS
DAVID VITTER, Louisiana, Chairman
TED STEVENS, Alaska FRANK R. LAUTENBERG, New Jersey,
JOHN McCAIN, Arizona Ranking
OLYMPIA J. SNOWE, Maine JOHN F. KERRY, Massachusetts
C O N T E N T S
Hearing held on April 26, 2006................................... 1
Statement of Senator Lautenberg.................................. 3
Statement of Senator Stevens..................................... 2
Statement of Senator Vitter...................................... 1
Akasofu, Dr. Syun-Ichi, Director, International Arctic Research
Center, University of Alaska Fairbanks......................... 39
Prepared statement........................................... 40
Armstrong, Dr. Thomas R., Program Coordinator, Earth Surface
Dynamics Program, U.S. Geological Survey, Department of the
Prepared statement........................................... 22
Corell, Dr. Robert W., Senior Fellow, American Meteorological
Society; Affiliate, Washington Advisory Group; Chair, Arctic
Climate Impact Assessment...................................... 47
Prepared statement........................................... 50
Murawski, Ph.D., Steven A., Director of Scientific Programs/Chief
Science Advisor, National Marine Fisheries Service and
Ecosystem Goal Team Lead, National Oceanic and Atmospheric
Administration, Department of Commerce......................... 5
Prepared statement........................................... 8
Reiter, Paul, Chief, Insects and Infectious Disease Unit;
Professor, Institut Pasteur.................................... 71
Prepared statement........................................... 73
Inouye, Hon. Daniel K., U.S. Senator from Hawaii, prepared
Response to written questions submitted by Hon. Daniel K. Inouye
to Steven A. Murawski, Ph.D.................................... 89
Response to written questions submitted by Hon. Frank R.
Dr. Syun-Ichi Akasofu........................................ 98
Steven A. Murawski, Ph.D..................................... 92
PROJECTED AND PAST EFFECTS
OF CLIMATE CHANGE: A FOCUS ON
MARINE AND TERRESTRIAL SYSTEMS
WEDNESDAY, APRIL 26, 2006
Subcommittee on Global Climate Change and Impacts,
Committee on Commerce, Science, and Transportation,
The Subcommittee met, pursuant to notice, at 2:30 p.m. in
room SD-562, Dirksen Senate Office Building, Hon. David Vitter,
Chairman of the Subcommittee, presiding.
OPENING STATEMENT OF HON. DAVID VITTER,
U.S. SENATOR FROM LOUISIANA
Senator Vitter. This is the Subcommittee on Global Climate
Change and Impacts of the Senate Commerce Committee, and our
hearing today is on the projected and past effects of climate
change, a focus on marine and terrestrial systems.
Thank you all for being here. Today, we'll have a hearing
on just that, the projected and past effects of climate change,
with a particular focus on marine and land systems.
It's clear that we are experiencing a warming trend. Many
scientists say that temperatures we're seeing right now are not
outside of historical ranges experienced on Earth; however, if
temperatures continue to increase, we would be entering
Similarly, carbon dioxide concentrations in both our
atmosphere and oceans are at levels never seen before. And
while I enjoy forging new frontiers in many areas, this is not
one any of us are excited to do.
So, this hearing will concentrate on the realized
historical and also future predicted impacts of climate change,
specifically on the health of our oceans, humans, plants and
animals, and other Earth systems.
I'm very interested in examining, through this hearing, how
much we can ascertain from historical climatic variation and
apply this knowledge to current and future changes and
conditions. For once, we're not here to argue about the causes
of observed warming trends or whether mandatory or market-based
incentives are the best solution to reducing greenhouse gas
emissions. Rather, we all agree that clearly understanding the
potential changes we face in our environment as a result of
this current cycle is an important task.
We've seen predictions that our seas will rise 30 feet, and
other extraordinary estimates. Certainly, I hope those won't
come true. If so, I imagine many of us will have to migrate to
higher ground in Alaska, maybe even run against Ted Stevens. I
don't look forward to that. I know what the outcome would be.
In addition, the State of Louisiana has many low-lying
coastal areas, as many in the Nation discovered after
Hurricanes Katrina and Rita. The impressive work of LSU's
Spatial Reference Center and the Center for GeoInformatics and
the National Geodetic Survey have been very helpful in
providing data we need in our part of the world, in terms of
that situation in south Louisiana.
So, we're facing many of these challenges at home. The land
is sinking, levees are settling. We lose a football field of
wetlands every 38 minutes. The Corps of Engineers is currently
rebuilding our flood and hurricane protection systems without
the design flaws of the past, but the issue of net sea-level
rise is very important as we do that work, as well.
Sea-level rise is just one component of the hearing today.
The State of Louisiana is the largest producer of fisheries in
the lower 48, and we need to gain a better understanding of how
ocean changes could affect our fishermen and the growing demand
for wild, domestic seafood.
We'll also discuss other potential changes related to our
polar and temperate glaciers, impacts on plants and animals,
and, of course, the important issue of human health.
I want to commend to my colleagues that we share the common
goal of ensuring the best science and understanding of all of
these potential future changes.
As CEQ Chair Jim Connaughton testified at our last hearing,
the U.S. is dedicating more resources to climate change science
and technology than any other country, probably more than all
other countries combined. We're seeing reductions in our
emissions intensity now, and we must continue these efforts to
meet national goals.
In closing, I want to point out that we have witnesses that
have traveled from Paris and Fairbanks to be with us today.
And, while I appreciate all of you being here today, I want to
extend a special thanks to Dr. Akasofu and Dr. Reiter for your
efforts to be with us. And I look forward to everyone's
With that, we'll turn to the full Committee Chairman,
STATEMENT OF HON. TED STEVENS,
U.S. SENATOR FROM ALASKA
The Chairman. Well, thank you very much, Senator Vitter,
for conducting this hearing.
At my suggestion, the full Committee created this new
subcommittee to deal specifically with global climate change.
And it's imperative that the decisionmakers in all our
governments and industry have the best possible science to rely
upon as we deal with the problems of global climate change.
There is a great deal of uncertainty, as we all know, about
the causes, but I don't think there's much, really, doubt that
there are changes taking place, and in particular in Alaska and
the Arctic. We have faced severe coastal erosion. We have faced
polar glacier recession. We have had melting permafrost,
migration of species, all sorts of problems regarding our
forests, and increased risks of fires in Alaska. And our native
villages have faced the problems of changes that are much
greater than taking place anywhere else in the United States.
We think that if we can understand and, really, watch
what's going on in Alaska, that the rest of the country will
learn from it. And I hope that this hearing will demonstrate
It is critical that we examine the problems of Alaska on
the basis of sound science, and that's why I'm delighted that
there are some familiar faces here today, for me. Dr. Bob
Corell is Chair of the Arctic Climate Impact Assessment Team,
and he's done a great deal of research. We'll learn more about
that today. And my long-time friend and advisor, Dr. Syun
Akasofu, who directs our International Arctic Research Center
in Fairbanks. He has, as you said, flown a long way, and I
think it's about the third time he's come down this year, at
our request, to appear in various ways. He earned his doctorate
in studying the composition of the aurora borealis--``northern
lights,'' to most people--and he's devoted 20 years now to
studying the climate of our area. So, I know of no one in the
world that I would rely on more than Syun, who has, I think,
demonstrated his objectivity and his honesty, in terms of
dealing with these issues.
So, again, I think that this is a very timely hearing. I
wish the whole Senate was here to listen to these people,
because these are the people that can give us the information
now that we ought to listen to as we try to consider some of
the suggestions that are being made concerning what the Federal
Government could do--should do concerning global climate
Thank you very much.
Senator Vitter. Thank you, Mr. Chairman.
And we also have our Ranking Member, Senator Lautenberg.
Thank you for being here, Senator. And if you have any
opening statement, please feel free to make it.
STATEMENT OF HON. FRANK R. LAUTENBERG,
U.S. SENATOR FROM NEW JERSEY
Senator Lautenberg. Thanks, Mr. Chairman. I'm pleased to be
here. And I'm pleased, particularly, that our Chairman of the
whole Committee is with us.
We have, Mr. Chairman, a vote that's started. And I don't
know what you'd like to schedule. Should we--I'll make my
statement, and then shall we adjourn for a few minutes to carry
on with our business? I'm----
Senator Vitter. Why don't we do just that, if it's----
Senator Lautenberg. Yes.
Senator Vitter.--agreeable to you.
Senator Lautenberg. That'd be perfect.
And one of the reasons that I'm pleased to share this
platform today with each of you is the fact that you, in
Louisiana and Alaska and New Jersey, are all threatened by
these climate changes that we see and that we worry about, the
sea-level rise and Atlantic storms, the increased air
pollution, harm to our fisheries. But we're also affected by
things that happen beyond our shores. We'll be harmed by the
impacts of global warming that occur across the oceans or on--
even on the other side of the world.
Now, if the Greenland ice sheet melts into the sea, we'll
be affected. If the glaciers of Central Asia disappear, taking
water used for drinking and irrigation for more than a billion
people with them, we will be affected. If the sea rises and
washes over homes in Bangladesh, we will be affected. And if a
range of plant and animal species go extinct, from frogs to sea
coral to polar bears, we, all of us, will be affected.
Thousands of scientists around the world have identified
potential impacts of global warming, and many of their dire
predictions are already coming true; in some cases, at a rate
far faster than forecasted. The indicators include increased
hurricane intensity, the retreat of glaciers, loss of sea ice,
and our oceans are becoming more acidic. There is no dispute
that these changes are occurring. Senator Stevens said it very
clearly, and there is broad scientific consensus, that the
global warming that we are experiencing is mostly due to human
activity, not the result of natural climate cycles.
The most common argument heard from those who oppose prompt
action to address global warming is that we don't want to wreck
our economy until we're absolutely sure that the threat is
real. Well, there are two fallacies to this argument. First,
reducing global warming will not wreck our economy. In recent
years, some companies have reduced greenhouse gases and have
actually found that they've saved money. Second, we can't
afford to delay taking action until every doubter is convinced.
Once greenhouse gases enter our atmosphere, they're going to
remain for a long time, and we can't continue to race toward
catastrophe, hoping that we can throw the car in reverse at the
last minute. We've got to slow it down now.
We've heard these doubters before. Every time a meaningful
protection of our environment or public health has been
proposed, they raise reasons as to why we shouldn't be
concerned about it now. The tobacco industry successfully
fought efforts to curtail its deadly products for decades,
based on the claim, ``We just didn't know enough.'' But we did
know enough to justify taking action.
In 1994, when President Clinton proposed stronger
protections from air pollution, industry-funded think tanks
argued that our economy would be ruined and that barbecues and
fireworks on the 4th of July would be barred. But after
President Clinton strengthened air-quality standards, our
economy did thrive, and fireworks and barbecues continued.
Now, we know that global warming is occurring. We also know
it will continue to increase even if we act quickly to flatten
and then reduce our greenhouse gas emissions. We know that the
impacts of this warming are already being observed, and that it
will continue and quicken, particularly if we take no action to
reverse our current course.
So, our country's got to act. And this doesn't mean that
when we act, that we'll see an immediate result. But at some
point a beginning has to be made, and failure to do so could be
our greatest failure as a nation and as human beings.
Now, I'm pleased that we have two panels of witnesses today
before us. I'm particularly interested in the views of Dr.
Corell, whose ideas on this matter are well respected, as are
others in the field of climate science.
Mr. Chairman, I went down to the South Pole a few years. I
wanted to see what the National Science Foundation was doing.
And it seemed to me, at night, that you could almost hear the
glaciers groaning as there were climate shifts and as the
temperatures changed. And 70 percent of the world's fresh water
was stored in those--in that ice. Much of that ice has
disappeared, and much more of it will disappear.
And so, once again, Mr. Chairman, I thank you for doing
this. I look forward to hearing from our witnesses, and sorry
that we have to delay them, but we'll be back. It's been said
Senator Vitter. Thank you, Senator.
And right now we'll take a very brief recess to vote on the
Senate floor, and we'll all return absolutely as quickly as
possible. I apologize for the delay.
Senator Vitter. We'll reconvene the hearing. Thanks to
everyone, particularly our witnesses, for their patience.
We'll start with Panel I, comprised of two individuals.
First, Dr. Steve Murawski, Director of Scientific Programs and
Chief Science Advisor for the National Marine Fisheries Service
and Ecosystem Goal Team Lead with the National Oceanic and
Atmospheric Administration, and then he'll be followed by Dr.
Thomas Armstrong, Program Coordinator of the Earth Surface
Dynamics Program with the U.S. Geological Survey.
Thank you both for being here. And, Dr. Murawski, please
STATEMENT OF STEVEN A. MURAWSKI, Ph.D., DIRECTOR OF SCIENTIFIC
PROGRAMS/CHIEF SCIENCE ADVISOR,
NATIONAL MARINE FISHERIES SERVICE AND ECOSYSTEM GOAL TEAM LEAD,
NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF
Dr. Murawski. Good afternoon, Chairman Vitter and Chairman
Stevens. Thanks for the opportunity to testify.
Among NOAA's diverse missions, our tasks include
understanding and predicting changes in the Earth's environment
and acting as the Nation's principal steward of coastal and
marine resources critical to our Nation's economic, social, and
Climate change is only one of a complex set of interacting
factors that simultaneously influence the marine ecosystems. It
is challenging, but vital, for us to isolate the influences of
individual factors, such as natural and anthropogenic climate
cycles and other influences, such as pollution, land
development, fishing pressures, and others on ecosystems.
In order to manage such a complex set of human activities,
NOAA is committed to an ecosystem approach that addresses the
many simultaneous pressures affecting resources, including the
effects of climate change.
Because changing climate is one of the significant long-
term influences on marine species, we must meet this challenge
head-on. Climate-related issues are of particular concern for
marine ecosystems that include the effects of long-term rising
sea levels, increasing acidification of the world's oceans,
bleaching of shallow-water coral reefs, loss of sea ice, and
rising water temperatures. All of these factors have been
documented as influencing marine ecosystems, and all are cause
for concern. As Winston Churchill said, ``The farther backward
you can look, the farther forward you're likely to see.''
Paleoclimate and paleoecological indicators provide
perspective on the scale of recent observed changes in marine
ecosystems. Over hundreds of thousands of years, numerous ice
ages and warming events have occurred, and populations have
responded by changing growth patterns, abundance, and
Over the last 10,000 years since the last ice age, there
were slightly warmer than average conditions during 1200 to
1400 A.D., slightly cooler conditions from 15- to 1800 A.D.--
that is the Little Ice Age--and an increase in the last
centuries to temperatures that are the warmest in the last
Companion biological records show that, as compared to the
preceding 1,000 years, organisms and the ecosystems are now
exhibiting unusual patterns of growth, abundance, distribution,
and other characteristics.
Recent changes in the Earth's climate are having observable
impacts on marine ecosystems and the human communities that
depend on them. Rising sea levels alter ecosystems and habitat
in coastal regions. The coastlines of our Atlantic and Gulf
States, as well as portions of Alaska and the Pacific Islands
are especially vulnerable to long-term sea-level rise. For
example, coastal Louisiana is projected to have sea-level rise
3 to 4 feet over the next century. Factors contributing to sea-
level rise in coastal Louisiana are complex and multifaceted.
Rising sea levels in coastal Louisiana are having effects on
coastal marshes that are important to nursery areas for Gulf
The oceans are the largest reservoir of carbon dioxide.
Estimates are that by the middle of this century, atmospheric
carbon dioxide levels will increase, resulting in a decrease in
the surface water pH by approximately 0.4 pH units.
As the oceans become more acidic, more species of marine
plankton will have a reduced ability to produce protective
calcium carbonate shells. These plankton species are the base
of the marine food web, and shifts in the base can have
cascading consequences through trophic levels. The loss of
calcium carbonate will also have negative impacts on the
world's coral reefs, which are areas of the highest
biodiversity in the ocean. Coral reefs are also extremely
vulnerable to sea surface temperatures. Rising global
temperatures over the past 30 years have been accompanied by an
increase in the extent and frequency of coral bleaching in many
tropical areas of the world. September of 2005 was, by far, the
warmest in the eastern Caribbean in the entire 100-year record
that we have. Many of these areas experienced over 90 percent
of corals bleached, and 30 percent of the corals have died in
some of these areas. This loss is significant, as coral reef
ecosystems are among the most diverse and biologically complex
areas in the oceans.
The loss of sea ice has been documented in both the Arctic
and the Antarctic. The amount and duration of ice cover in the
southeast Bering Sea has decreased substantially since the
early 1970s as the southeast Bering Sea has warmed 2 to 3
degrees Centigrade in the past 10 years. These changes have had
substantial biological impacts on the distribution and
abundance of many commercial finfish and shellfish species.
This means that the resource base supporting individual
communities has been displaced, affecting the economics of
fisheries and the communities. Other changes in the food web of
the Bering Sea have occurred, affecting marine mammals and
subsistence hunting for them.
Temperatures in the South Shetland Islands in Antarctica
have warmed by over 4 degrees Centigrade since the 1940s, and
the extent of ice around Antarctica has declined appreciably.
The density of krill, a central link in the Antarctic food web,
has decreased by more than 90 percent in the region since 1976.
Declines in krill have been associated with decreasing
populations of penguins, seals, and other marine life.
In temperate regions, many marine fish and shellfish
species have been observed to shift their distributions
northward in response to warmer waters.
This is just a sample from the growing body of evidence
linking climate change to marine ecosystem function. It is our
challenge to understand these linkages both to better predict
their effects and to identify the conservation and management
policies in the face of changing climate that may help to
mitigate their effects.
Improving the predictability of ocean responses to a
changing climate will require improvements in ocean observing,
research, and modeling. A large broadscale and robust system
for observing and measuring oceanographic climate and economic
conditions is essential to better understanding climate change
effects and ecosystem effects.
To provide such a comprehensive set of measurements, the
Administration and NOAA have supported the development of the
U.S. Integrated Ocean Observing System, or IOOS. The full
development of IOOS is a high priority for improving our
understanding of climate effects on marine ecosystems.
And, last, the President's FY 2007 budget request restores
significant cuts made by Congress in NOAA's climate program in
2006. This funding is critical to NOAA's ability to understand
and study climate change, including the impacts of climate on
ecosystems. And we urge the Committee to support NOAA's FY 2007
Thank you, Mr. Chairman. I'd be happy to answer questions.
[The prepared statement of Dr. Murawski follows:]
Prepared Statement of Steven A. Murawski, Ph.D., Director of Scientific
Programs/Chief Science Advisor, National Marine Fisheries Service and
Ecosystem Goal Team Lead, National Oceanic and Atmospheric
Administration, Department of Commerce
Good afternoon, Mr. Chairman and Members of the Committee. My name
is Steven Murawski, and I am the Director of Scientific Programs and
Chief Science Advisor at the National Marine Fisheries Service (NMFS),
within the National Oceanic and Atmospheric Administration (NOAA). I
also serve as leader of NOAA's Ecosystem Goal Team, which integrates
the Agency's many ecological activities across its various offices.
Thank you for inviting NOAA to discuss projected and past effects of
climate change with a focus on marine and terrestrial ecosystems. Among
NOAA's diverse missions, our tasks include understanding and predicting
changes in the Earth's environment and acting as the Nation's principal
steward of coastal and marine resources critical to our Nation's
economic, social and environmental needs.
Today I will focus my remarks on how changes in climate affect
marine ecosystems, particularly as they relate to NOAA's stewardship
responsibilities. NOAA's work on climate change and ecosystems relevant
to this hearing includes observations of the physical environment and
biota, research to understand the changes in the environment and the
broader ecosystem, and incorporating projected impacts of climate
change into NOAA's conservation and management programs for living
marine resources and ecosystems. Climate change is only one of a
complex set of factors that influence marine ecosystems. It can be
difficult to separate the influence of natural climate cycles, recent
climate change, and other factors such as overfishing, air pollution
such as sulfates, agricultural run-off, land use changes resulting from
land fills, drainage practices, uses of pesticides and fertilizers,
development, recreational facilities and practices, inadequate storm
water management, and sewage treatment. NOAA is committed to an
ecosystem approach to resource management that addresses the many
simultaneous pressures affecting ecosystems.
This Administration recognizes climate change as a complex and
important issue and acknowledges human activities are contributing to
recent observed changes in the climate system. However, scientific
uncertainties still remain, including how much of the observed warming
is due to human activities and how large and fast future changes will
be. In 2002, the Administration created the Climate Change Science
Program (CCSP; the Federal interagency program focused on climate
change research) to ensure the Federal Government's efforts and
resources are used to obtain the best possible scientific knowledge as
the foundation to address challenging climate change questions and
support decisionmaking. There is much important research yet to be done
and CCSP--whose leadership resides in NOAA--is seeking to increase our
understanding of climate change. Within CCSP there is an Ecosystem
Interagency Working Group which is currently examining a variety of
topics relevant to today's hearing, including: (1) the use of
integrated modeling systems, observations, and process studies to
project the effects of climate variability and change on near-coastal
and marine ecosystems and communities; (2) combined effects of changes
in land use and climate on non-point sources of pollution entering
estuaries; and (3) a long-term study of the western U.S. mountains and
the relationship of observed sudden ecosystem changes to changes in
The Climate Change Science Program is a coordinated effort across
13 agencies (U.S. Agency for International Development; Department of
Agriculture; Department of Commerce, National Oceanic and Atmospheric
Administration and National Institute of Standards and Technology;
Department of Defense; Department of Energy; Department of Health and
Human Services, National Institutes of Health; Department of State;
Department of Transportation; Department of the Interior, U.S.
Geological Survey; Environmental Protection Agency; National
Aeronautics and Space Administration; National Science Foundation; and
the Smithsonian Institution), 12 of which fund CCSP research. Funding
for NOAA's CCSP initiatives are included within the NOAA Climate
Program. The fiscal 2007 President's budget request for NOAA includes
spending for CCSP near-term research focus areas, including integrating
new remote-sensing observations with expanded observations to build the
next generation of climate prediction capabilities; development of an
integrated Earth system analysis capability; integrating of water cycle
observations, research and modeling; using global LANDSAT data to
answer critical climate questions; an integrated North American Carbon
Program; understanding the impacts of climate variability and change on
ecosystem productivity and biodiversity; coping with drought through
research and regional Partnerships; the International Polar Year; and
an Integrated Ocean Observing System. The President's budget restores
cuts made by Congress to NOAA's Climate Program in 2006, particularly
in the area of Research Supercomputing, critical to NOAA's ability to
reduce some of the highest uncertainties in understanding impacts of
climate variability and change. We urge the Committee to support the FY
2007 President's budget request for NOAA.
In my testimony today I will: (a) provide information on NOAA's
contributions relevant to climate change science and links to effects
on marine ecosystems, (b) detail the importance of understanding
climate-ecosystem links both for the affected marine areas and the
human communities dependent upon them, (c) briefly describe some
paleontological observations of how ecosystems have changed in response
to climate variations in the past, and (d) review some contemporary
observed changes in marine ecosystems thought to be related to changes
in the Earth's climate and issues surrounding them. Finally, I will
outline some of the scientific challenges and needs for improving
science to better define ecosystem impacts and inform conservation and
management strategies for living marine resources taking into account
NOAA's Roles in Climate and Ecosystem Sciences
Within the climate science community, NOAA is a recognized leader
both nationally and internationally. Our scientists actively
participate in many important national and international climate
working groups and assessment activities. One of NOAA's mission goals
is to ``understand climate variability and change to enhance society's
ability to plan and respond.'' NOAA is the only Federal agency that
provides operational climate forecasts and information services
(nationally and internationally). NOAA is the leader in implementing
the Global Ocean Observing System (NOAA contributes 51 percent of the
world-wide observations to GOOS, not including satellite observations).
NOAA also provides scientific leadership for the Intergovernmental
Panel for Climate Change Working Group I and CCSP. To better serve the
Nation, NOAA recently created a Climate Program Office (CPO) to provide
enhanced services and information for better management of climate
sensitive sectors, such as energy, agriculture, water, and living
marine resources, through observations, analyses and predictions, and
sustained user interaction. Services include assessments and
predictions of climate change and variability on timescales ranging
from weeks to decades.
Within the ecosystem community, NOAA's ecosystem researchers have
been at the forefront of establishing links between ocean variability
and impacts on marine ecosystems. NOAA has funded some research
programs specifically dedicated to evaluating impacts of changes in the
physical environment on marine resources. These include a program
jointly undertaken with the National Science Foundation called GLOBEC
(Global Ocean Ecosystem Dynamics), which just last week co-hosted a
symposium on ``Climate variability and ecosystem impacts on the North
Pacific'' with PICES (the North Pacific Marine Science Organization of
which the U.S. is also a member). An exclusively NOAA program called
NPCREP (North Pacific Climate Regimes and Ecosystem Productivity) seeks
to improve climate-ecosystem science in the Alaskan Large Marine
Ecosystem complex. Even more information on the impacts of climate on
marine ecosystems is derived from NOAA's many observing programs
established to aid in the management of fisheries, protected species,
marine sanctuaries, corals and other specific Agency mandates.
These data, primarily collected in support of NOAA's ecosystem
stewardship authorities, provide a wealth of information for
interpreting climate impacts when combined with NOAA's climate,
oceanographic and weather information. Results of these analyses have
been widely disseminated and NOAA's contributions to the emerging
science of ecosystem impacts of climate change have been significant.
However, a greater understanding of the full range of climate induced
impacts on ecosystems will require us to increase our observation of
ecosystems in relation to variable climate forcing and focus our
research on the mechanisms through which ecosystems are affected. In
this way we can develop quantitative assessments and projections of
climate's ecological impacts, including impacts on the resources on
which human communities rely.
Why are Links between Climate and Marine Ecosystems So Important?
Irrespective of the ultimate causality, changes in the world's
climate has resulted in changes in marine ecosystems, on several
different time scales, affecting the abundance, distribution and
feeding relationships among components of many marine communities
\1\, \2\, \3\, \4\,
\5\, \6\ While we are still working toward a complete
understanding of the causes of the observed phenomena, recent
projections indicate that a number of climate change scenarios have the
potential to affect marine ecosystems in even more fundamental ways.
These changes are related both to long-term trends in the ocean
environment and to the cyclic variation in ocean conditions observed in
many areas. These changes are important in their own right, but even
more so because of the dependence of many of our coastal communities on
living marine resources--for food, recreation, and cultural
fulfillment. Over half of the U.S. population now lives within 100
miles of the coast, and this proportion is increasing dramatically. Our
$60 billion per year seafood industry, marine tourism industries,
recreational activities, and the very existence of some communities may
be dependent on changing ocean conditions affecting marine ecosystems.
Changing climate is one of the most significant long-term
influences on the structure and function of marine ecosystems and must
therefore be accounted for in NOAA's management and stewardship goals
to ensure healthy and productive ocean environments. Changes and
variations in climate may directly or indirectly impact marine
ecosystems. This includes changes and variations of sea surface
temperature, ocean heat content, sea level, sea ice extent, freshwater
inflow and salinity, oceanic circulation and currents, pH, and carbon
inventories. Each of these properties of the global ocean is being
measured to varying degrees by NOAA. Through the continued collection
of data and the implementation and integration of observing systems, we
strive to create longer, more globally inclusive data records that will
improve our understanding of climate change and our ability to reliably
predict impacts on marine ecosystems over time scales of interest to
our constituents now (e.g., 5-10 year time horizon) and in the future.
A Paleontological Perspective on the Impacts of Climate Change on
The paleoclimate record provides a long view of how populations and
entire ecosystems have responded to climate change over hundreds to
thousands of years. Many sources of paleoclimate data are from
biological indicators such as tree rings, corals, and fossil plankton.
By comparing the time series from biological indicators with
paleoclimate data from non-biological material such as ice cores,
boreholes, and cave stalagmites, one can reconstruct not only how
climate has changed, but also how marine and terrestrial populations
Over hundreds of thousands of years, ice ages have come and gone,
and populations have responded by changing growth patterns, abundance
and geographic location. Remarkably only a few documented extinctions
occurred in terrestrial and marine ecosystems during ice age cycles,
apart from the extinction of the Pleistocene megafauna (e.g., the
woolly mammoth). Just as the changes in climate during the ice ages
were large and sometimes abrupt, ecosystem changes were similarly large
and abrupt. For example, at the end of the last ice age, pollen from
lake sediments indicate an abrupt northward migration and establishment
of the modern biomes across North America,\7\ while in the adjacent
oceans fossil plankton from marine sediments reveal that the region
where certain plankton species were abundant also moved to higher
While these changes in the ocean environment were abrupt compared
to the radiation changes that caused the ice ages, the changes were
slow compared to the changes occurring in the current millennium. The
end-of-the-ice-age ecosystem changes occurred over thousands of years.
Over the last 10,000 years climate has remained relatively stable apart
from small changes caused by the changes in seasonal solar radiation.
Over the past 1,000 years, where the paleoclimate record is most
complete, climate has been even more constant except for the recent
trends in temperature and rainfall. The climate of the last 1,000 years
can be characterized as: 1200-1400 AD--slightly warmer than average
conditions; 1500-1800 AD--slightly cooler than average conditions; and
1900-2000 AD--an increase in the last centuries to temperatures that
are likely to be the warmest in the last millennium.\9\,
\10\ Companion biological records show that organisms and ecosystems
are changing in growth pattern, abundance, and other characteristics in
ways that are unusual compared to the preceding 1,000 years. Detailed
information on terrestrial and marine ecosystem responses to past
climate change is detailed on the NOAA Paleoclimatology website
(www.ncdc.noaa.gov/paleo). One selected example relevant to marine
ecosystems involves the long record of sockeye salmon populations in
The paleoclimate record of sockeye salmon from Alaskan lakes
reveals the difficult task of separating the influence of natural
climate cycles, recent climate change, and fishing pressure on salmon
abundance. Sockeye salmon return to lakes in Alaska to spawn, and their
remains are reflected in chemical (e.g., nitrogen-15) concentrations in
lake sediments, creating a 2000 year-long record of salmon abundance.
Dr. Bruce Finney, from the University of Alaska, and his colleagues
correlated centuries-long cycles in salmon abundance with climate
variations from other paleo proxies, demonstrating the existence of
natural cycles in salmon populations prior to significant human
activity in the region.\11\ Near the end of the record the decline due
to intense fishing pressure in the last century is also evident. Finney
and colleagues note that natural cycles in salmon abundance appear out
of phase with the abundance of other fish species farther south in the
California Current system, a pattern they also attribute to natural
climate variability. In addition to fish abundance, paleo-ecological
records have also been developed for plankton that form the base of the
food chain. Compared to the fish proxies, the plankton records are more
complete and subject to fewer uncertainties. While these records are
continuously being developed, the records published so far document a
clear link between climate change and marine ecosystems. One important
conclusion from this work is that marine ecosystems are sensitive to
even small changes in climate.
Current and Projected Impacts of Climate Change on Marine Ecosystems
and Living Marine Resources
Impacts of Sea Level Rise on Ecosystems
Sea level rise is projected to accelerate during the 21st century,
with the most significant impacts in low-lying regions where subsidence
and erosion problems already exist. Rising sea level has worldwide
consequences because of its potential to alter ecosystems and habitat
in coastal regions. Sea level rise and global climate change issues in
the coastal zone include:
Higher (deeper) and more frequent flooding of wetlands and
Increased flooding due to more intense storm surge from
severe coastal storms;
Increased wave energy in the nearshore area;
Upward and land-ward migration of beaches;
Accelerated coastal retreat and erosion;
Saltwater intrusion into coastal freshwater aquifers;
Damage to coastal infrastructure; and
Broad impacts on the coastal economy.
The coastlines of our Atlantic and Gulf states, as well as portions
of the Alaska coastline are especially vulnerable to long-term sea
level rise. The slope of these areas is so gentle that any small rise
in sea level can produce a large inland shift of shoreline.
Sea level rise threatens to alter wetland ecosystems. Sea level
rise may also result in increased susceptibility to nutrient-related
eutrophication, due to changes in estuarine circulation. Changes in the
wetland and estuarine processes will affect resident marine organisms
and the fisheries dependent upon them.
NOAA has maintained long-term continuously operating stations of
the National Water Level Observation Network (NWLON), and has recently
documented the relative sea level trends at all of the longest-term
stations (1854-present). The map below (also available at http://
tidesandcurrents.noaa.gov/sltrends/slrmap.html) shows sea level trends
for the United States for those locations where tide stations exist.
This map provides an indication of the differing rates of relative sea
level rise (vertical land and sea level motion combined) around the
United States. There is a general scientific agreement that sea level
rise is occurring at a global average rate of 2 mm per year. Referring
to the map the mid-Atlantic and Gulf Coast are experiencing 3-5 mm and
5-15 mm per year rise in sea level, respectively.
One area particularly vulnerable to sea level rise is coastal
Louisiana. The graphic above illustrates that these areas are projected
to have sea levels rise 3-4 feet over the next century. Factors
contributing to sea level rise in coastal Louisiana are complex and
multifaceted, including land subsidence due to petroleum extraction,
declining sediment loads deposited from rivers into the marshes, land
use practices exacerbating wetlands loss, and rising sea levels due to
global climate change and other factors. Whatever the causes, a 3-4
foot rise in sea level in coastal Louisiana will have profound effects
on marine resources, since coastal marshes there are important nursery
areas for most of the valuable living resources (e.g., shrimp, oysters,
many finfish species) in the Gulf of Mexico. In addition, loss of
Louisiana's coastal marshes to sea level rise makes coastal communities
much more vulnerable to recurring storm events.
The Northwestern Hawaiian Islands (NWHI) are of particular concern
with respect to sea level rise. The NWHI have high conservation value
due to their concentration of endemic, endangered and threatened
species, and large numbers of nesting seabirds. Most of these islands
are low-lying and therefore potentially vulnerable to increases in
global average sea level. The potential for NWHI habitat loss was
recently assessed by the NMFS Pacific Islands Fisheries Science Center,
by creating topographic models of several islands and atolls in the
NWHI and evaluating the potential effects of sea-level rise by 2100
under a range of basic passive flooding scenarios. Projected
terrestrial habitat loss varied greatly among islands: 3 percent to 65
percent under a median scenario (48-cm rise), and 5 percent to 75
percent under the maximum scenario (88-cm rise). Spring tides may
repeatedly inundate all land below 89 cm (median scenario) and 129 cm
(maximum scenario) in elevation. Sea level is expected to continue
increasing after 2100, which would have greater impact on atolls such
as French Frigate Shoals and Pearl and Hermes Reef, where virtually all
land is less than 2 m above sea level. Higher islands such as
Lisianski, Laysan, Necker, and Nihoa may provide longer-term refuges
for species. The effects of habitat loss on NWHI biota are difficult to
predict, but may be greatest for endangered Hawaiian monk seals,
threatened Hawaiian green sea turtles, and the endangered Laysan finch
at Pearl and Hermes Reef.
The oceans are the largest natural long-term reservoir for carbon
dioxide, absorbing approximately one-third of the carbon dioxide added
to the atmosphere by human activities each year. Over the past 200
years the oceans have absorbed 525 billion tons of carbon dioxide from
the atmosphere, or nearly half of the fossil fuel carbon emissions over
this period. Over the next millennium, the global oceans are expected
to absorb approximately 90 percent of the carbon dioxide emitted to the
For over 20 years, NOAA has participated in decadal surveys of the
world oceans, documenting the ocean's response to increasing amounts of
carbon dioxide being emitted to the atmosphere by human activities.
These surveys confirm that oceans are absorbing increasing amounts of
carbon dioxide. Estimates of future atmospheric and oceanic carbon
dioxide concentrations, based on the Intergovernmental Panel on Climate
Change emission scenarios and general circulation models, indicate that
by the middle of this century atmospheric carbon dioxide levels could
reach more than 500 parts per million (ppm), and near the end of the
century they could be over 800 ppm. This would result in a surface
water pH decrease of approximately 0.4 pH units as the ocean becomes
more acidic, and the carbonate ion concentration would decrease almost
50 percent by the end of the century. To put this in historical
perspective, this surface ocean pH decrease would be lower than it has
been for more than 20 million years.\13\
Recent studies indicate that such changes in water chemistry, or
ocean acidification as the phenomenon is called, would have effects on
marine life, such as corals and plankton.\13\, \14\ The
carbonate chemistry of seawater has a direct impact on the dissolution
rates of calcifying organisms (coral reefs and marine plankton). As the
pH of the oceans decreases and becomes more acidic, some species of
marine algae and plankton will have a reduced ability to produce
protective calcium carbonate shells. This makes it more difficult for
organisms that utilize calcium carbonate in their skeletons or shells
to build and maintain their structures. These organisms form the
foundation of the food chain, upon which other marine organisms feed.
Decreased calcification may also compromise the fitness or success of
these organisms and could shift the competitive advantage toward
organisms not dependent on calcium carbonate. Carbonate skeletal
structures are likely to be weaker and more susceptible to dissolution
and erosion. There is paleooceangraphic evidence that during the last
high CO2 regime (55 million years ago) increased ocean
acidification was associated with mass extinctions of phytoplankton
species, followed by a recovery period of about 80,000 years.\15\
Because of the importance of phytoplankton to marine food webs,
biodiversity and productivity of the oceans may be altered \14\, which
may result in adverse impacts on fishing, tourism, and other economies
that rely on the continued health of our oceans.
Recent findings indicate that such conditions could develop within
decades at high latitudes.\14\ This will likely have impacts on high
latitude ecosystems because pteropods, a shelled, swimming mollusk, is
a significant prey item for fish in these regions. It is important to
gain a better understanding of how ocean chemistry and biology will
respond to higher carbon dioxide conditions so that predictive models
of the processes and their impacts on marine ecosystems can be
Coral Bleaching Events
Coral reef ecosystems are among the most diverse and biologically
complex ecosystems on Earth and provide resources and services worth
billions of dollars each year to the United States economy and
economies worldwide. Coral reefs support more species per unit area
than any other marine environment, including about 4,000 species of
fish, 800 species of hard coral and thousands of other species.
Approximately half of all federally-managed fish species depend on
coral reefs and related habitats for a portion of their life cycles.
The National Marine Fisheries Service estimates the annual commercial
value of U.S. fisheries from coral reefs is over $100 million. Local
economies also receive billions of dollars from visitors to reefs
through diving tours, recreational fishing trips, hotels, restaurants,
and other businesses based near reef ecosystems. In the Florida Keys,
for example, coral reefs attract more than $1.2 billion annually from
tourism. In addition, coral reef structures buffer shorelines against
waves, storms and floods, helping to prevent loss of life, property
damage and erosion.
Coral reefs are extremely vulnerable to increased sea surface
temperatures. As global temperatures have risen over the past 30 years,
there has been a corresponding increase in the extent and frequency of
extremely high sea surface temperatures and coral bleaching events in
many tropical regions.\4\, \16\
Coral bleaching is a response of corals to unusual levels of stress
primarily thought to be associated with light and ocean temperature
extremes. Bleaching occurs when corals expel their symbiotic algae and
lose their algal pigment. Loss of the symbiotic algae leaves the coral
tissue pale to clear and, in extreme cases, causes a bleached
appearance. Corals often recover from mild bleaching. However, if the
stress is prolonged and/or intense, the corals may die or weaken,
causing them to be more susceptible to disease and other stressors.
Coral bleaching has occurred in both small localized events and at
large scales. Although many stressors can cause bleaching, mass
bleaching events have almost exclusively been linked to unusually high
ocean temperatures. There is still much that we do not know about the
impacts of bleaching-associated mass coral mortality on: (1) the
function of coral reef ecosystems; (2) the associated fisheries; and
(3) the value (loss) to recreation and tourism industries.
Through satellite and in situ monitoring of thermal stress, NOAA
tracks the conditions that may lead to coral bleaching. When the data
show that conditions are conducive to bleaching, NOAA provides watches,
warnings, and alerts to users throughout the globe through NOAA's Coral
Reef Watch project and Integrated Coral Observing Network. Coral
bleaching alerts allow managers and scientists to deploy monitoring
efforts which can document the severity and impacts of the bleaching to
improve our understanding of the causes and consequences of coral
Large scale or mass bleaching events were first documented in the
eastern Pacific in the early 1980s in association with the El Nino
Southern Oscillation.\16\ In 1997-1998, coral bleaching became a global
problem when a strong El Nino (period of warmer than average water
temperature), followed by a La Nina (period of colder than average
water temperature) caused unprecedented coral bleaching and mortality
However, coral bleaching events are not only tied to the El Nino/La
Nina phenomena. In 2005, a year lacking El Nino or La Nina climate
patterns, unusually warm temperatures were recorded in the tropical
North Atlantic, Caribbean, and Gulf of Mexico. Corals in the Caribbean
region experienced temperatures in 2005 that greatly exceeded any of
the previous 20 years. While the thermal stress in the Caribbean has
increased over the last 20 years, 2005 was a major anomaly from the
upward trend in temperatures there. As a result of NOAA satellite and
in situ monitoring, we were able to alert managers and scientists to
this temperature anomaly. The unusually warm temperatures gave rise to
the most intense coral bleaching event ever observed in the Caribbean.
NOAA is working with local partners in Florida, Puerto Rico and the
U.S. Virgin Islands to better assess the impacts from the 2005
bleaching event. It is clear that mass bleaching is a serious concern
to the communities that depend upon these resources.
Preliminary analyses by NOAA show that the cumulative thermal
stress for 2005 was 50 percent larger than the cumulative stress of the
prior 20 years combined.\18\ September 2005 was by far the warmest
September in the Eastern Caribbean in the entire 100-year record. Many
areas, including the U.S. Virgin Islands, averaged over 90 percent of
their corals bleached and some have already lost 30 percent of these
corals due to direct thermal stress or subsequent disease. NOAA is
currently analyzing the impact of this bleaching event on already
vulnerable elkhorn and staghorn coral species. These two species have
been proposed for listing as ``threatened'' under the Endangered
NOAA and the Department of the Interior (DOI) are leading the
interagency effort of the U.S. Coral Reef Task Force to respond to and
assess the massive coral bleaching event in the Caribbean region in
2005. This effort has engaged many government and non-government
partners from across the region to assess the impacts of the massive
event and make recommendations on how to prepare for and address future
events. For example, NOAA, DOI, and the National Aeronautics and Space
Administration (NASA) conducted missions in October and December 2005
to examine the extent of bleaching and recovery/mortality of corals
within the Buck Island Reef National Monument, as well as obtain aerial
and hyperspectral imagery to quantify the extent of bleaching within
St. Croix, St. John, and southwestern Puerto Rico. Initial findings
indicate that in many areas, including the U.S. Virgin Islands, over 90
percent of coral cover had bleached. While some recovery had occurred
by December, hardest hit areas have already had over 30 percent of
their coral die. Further analyses are currently underway.
Impacts of Climate on Fisheries and Protected Resources
NOAA has stewardship responsibilities for coastal and living marine
resources from over 90 Acts of Congress. Resources managed under these
authorities are extremely valuable to the country, with fisheries alone
contributing over $60 billion a year and 520,000 jobs to the U.S.
economy. Interannual climate variability (e.g., El Nino, La Nina) and
trends (e.g. global warming) can cause profound geographic shifts in
marine ecosystems and are of great consequence to fishery-dependent
communities. Climate variability/change impacts environmental
conditions on multiple time scales, ranging from interannual to
decadal; since Earth's temperature is warming on a global scale, it is
important to assess the environmental impacts on large marine
In the past several decades, there have been significant changes in
the distribution, growth, and abundance of living marine resources
resulting from changes in ocean temperatures and related ocean
conditions. These changes have occurred in polar regions, in temperate
waters, and in the tropics. These changes have altered the productivity
and structure of marine food webs and change the flow of goods and
services to coastal communities. Below are cited some specific examples
of ecosystems changes documented by NOAA that are likely linked to
Polar Regions: Loss of sea ice at high latitudes has been
documented in a number of recent scientific articles and other forums.
Until recently, the northern Bering Sea ecosystem had extensive
seasonal sea ice cover and high water column and sediment carbon
production. Recently, NOAA researchers and other colleagues have
demonstrated that these ecosystems are shifting away from these
characteristics.\2\, \19\ The amount and duration of ice
coverage in the southeast Bering Sea has decreased substantially since
the early 1970s. In addition, the southeast Bering Sea has warmed 2-3+C
over the past 10 years. Recent work has documented differences in ice
coverage and thickness as far north as St. Lawrence Island in the
northern Bering Sea. These changes have substantial impacts to both
arctic and subarctic marine species in the area. For example, Greenland
turbot, a flatfish that prefers cold temperatures, has shown a steady
decrease in abundance since the mid-1970s. During this same time
period, abundance of walleye pollock, which prefers warmer waters, has
increased dramatically, with the present landings valued at $295
million per year. Bering Sea snow crab distribution has shifted
northward, and pollock distribution in the Bering Sea may soon follow,
affecting ecosystem interactions, fishery assessment surveys and the
economics of the fishing fleet which have to travel farther and spend
more days at sea to find and capture the same number of fish. In
addition, juvenile pollock act as forage fish in this ecosystem and
changes in their abundance, size, or distribution has the potential to
affect marine mammals.
Changes in the Bering Sea marine mammals have also been observed.
Gray whales have shifted their distributions northward, apparently in
response to decreases in sea ice and declines in their preferred prey
on the ocean floor.\20\ In addition, ice-dependent seals (ring,
spotted, bearded, and ribbon seals) require ice for parts of their life
history (molting and pupping) and there is concern that these animals
are being forced away from suitable feeding grounds as the ice
retreats.\21\ Similar concerns have been expressed regarding polar bear
and walrus populations in Alaska.\21\, \22\ These changes to
the ecosystem have clear implications for subsistence harvests in
Alaskan native communities.
In addition to the effects of climate variability and change on the
distribution and abundance of commercially important species of fish
and shellfish, as well as marine mammal species important to
subsistence hunters, the reduction in the extent and duration of sea
ice in the Bering and Chukchi Seas in recent years has led to serious
erosion problems for several remote villages and towns, including
Barrow, Pt. Lay, Wales, and particularly in the village of Shishmaref.
In these villages, traditionally the sea ice would buffer the impacts
of storm driven waves during the winter and spring. With less sea ice,
wave action is causing serious erosion problems and threatening
buildings and roads. To better predict the likely rate at which erosion
will impact this area, requires better information on trends in sea
level height, extent and duration of sea ice, and storm frequency.
Decreases in sea ice appear to be affecting other ecosystems as
well. The annual air temperature near the South Shetland Islands,
Antarctica has warmed by over 4+C since the 1940s \23\ and ice extent
around areas of Antarctica monitored by NOAA has declined
appreciably.\24\ Air temperatures at Palmer station are closely
correlated with the annual amount of ice cover. While air temperatures
in the Shetlands have increased, the density of krill, a shrimp-like
organism that is the central link in the Antarctic food web has
decreased by more than 90 percent in the region since 1976.\25\ Warming
of Antarctic waters and loss of ice affect predator (seals, penguins,
whales, etc.) and krill populations in the Southern Ocean in several
ways. Krill are a keystone species in the Antarctic because so many
species (fish, seals, penguins, sea birds, whales) feed upon them.
Declines in krill populations will negatively affect populations of
krill predators. Over the past two decades, populations of Adelie and
chinstrap penguins have declined significantly on the Antarctic
Peninsula, and the average reproduction rate of fur seals in the South
Shetlands has slowed as well. Years of low sea ice appear to be
associated with low krill production but relatively high populations of
salps (a gelatinous zooplankton, of little nutritional value to krill
predators).\5\ In addition, some predators are dependent upon sea ice
to haul out and rest during the over-wintering migrations, and declines
and shifts in sea-ice will impact their movements and distributions.
Thus, climate-related changes in the environment of Antarctica have had
and will likely continue to have important consequences for the marine
ecosystems of the region.
Temperate Regions: Climate-induced shifts in species distribution
and abundance have been observed in the temperate regions of the
Atlantic and Pacific. Many marine fish species have been observed to
shift their distributions northward in response to warming
waters.\3\, \26\ Populations of surf clams, an economically
important species along the mid-Atlantic coast of the United States
(particularly from New Jersey to Virginia), show evidence of increased
mortality in the southern regions of their territory. This is thought
to be due to elevated sea temperatures.\27\ These populations are also
susceptible to low oxygen events that may increase in frequency and
severity with the anticipated warming in the Mid-Atlantic region. A
severe low oxygen event off New Jersey in 1976 caused economic losses
of over $70 million to the clam fishery and it was many years before
the clam populations recovered.\28\ Declining recruitment levels of
some species linked to cooler water temperature (e.g., yellowtail
flounder in Southern New England) impedes rebuilding of the stock to
provide long-term sustainable fisheries.
In the western North Atlantic, a study of the distribution patterns
of three dozen pelagic and demersal fish species was conducted using
consistent data from over three decades to examine impacts of water
temperature changes on geographic distributions.\25\ This study
revealed a set of species whose center of distribution shifts from 0.5-
0.9 degrees of latitude pole-ward for each degree Celsius of water
temperature increase. Because not all species responded in this manner,
there is likelihood that the structure of predator-prey relationships
in the ecosystem would be altered under a scenario of long term warming
of Atlantic waters.\17\, \24\ Studies from the eastern
Atlantic have drawn similar conclusions. In the southern North Sea,
there has been a gradual replacement of species with primarily cold
water affinities with ones previously associated with more southern
In the California Current ecosystem there have also been sustained
shifts in the dominance of various fish species over the past few
decades. Off California, the dominant fish fauna has shifted from cold-
water species to ones of primarily warm water affinities. These changes
have occurred gradually over a sustained two decade period, and are
confounded by overfishing of many of the stocks.
From the 1970s through the 1990s there were overall declines in the
California fishery landings that coincided with an unprecedented period
of unusually warm ocean conditions and a decline in ecosystem
productivity.\30\ Changes in the survival of Pacific salmon appear to
follow a decadal-scale cycle (the Pacific Decadal Oscillation, or PDO),
with salmon survivorship being relatively high during the cool periods
and low during warm periods.\6\ In addition the California sardine
collapse in the 1940s was driven in part by a shift to cooler
conditions and a different ecosystem structure. Ocean sediment records
indicate sardine biomass has fluctuated for centuries on time scales
associated with decadal-scale shifts in the north Pacific
Climate and weather patterns over the North Atlantic are strongly
influenced by the relative strengths of two large-scale atmospheric
pressure cells--the Icelandic Low and a high pressure system generally
centered over the Azores in the eastern Atlantic. A deepening of the
Icelandic Low often corresponds with a strengthening of the Azores High
and vice versa. This see-saw pattern is called the North Atlantic
Oscillation (NAO) and a simple index of its state is given by the
difference in sea level pressure between the Azores and Iceland.
When the NAO index is positive, we see an increase in westerly
winds across the Atlantic and in precipitation over southeastern
Canada, the eastern seaboard of the United States, and northwestern
Europe.\3\ We also see increased storm activity tracking toward Europe.
Water temperatures are markedly low off Labrador and northern
Newfoundland, and warm off the United States. Conversely, when the NAO
index is negative, we have decreased storminess, and drier conditions
over southeastern Canada, and colder conditions over the eastern United
States and northwestern Europe. Water temperatures are warmer off
Labrador and Newfoundland, but cooler off the eastern United States.
These changes in the state of the North Atlantic Oscillation show a
tendency to persist on decadal time scales. The NAO was generally
positive during the 1980s and 1990s but has shown a tendency to
decrease since about the year 2000.
Variation in the NAO has very different effects on cod recruitment
on the western and eastern Atlantic.\3\ The direction of the NAO effect
on cod recruitment exhibits patterns consistent with the regional
manifestation of the NAO in the North Atlantic, with a coherence in the
NAO effect in northern Canada and Iceland and between southern Canada-
United States and western Europe. The decline in cod in areas such as
the North Sea has been linked to the interplay of over-exploitation and
changes in the planktonic ecosystem affecting the food supply of larval
cod (which is in turn affected by the NAO). Specifically, the supply of
the copepod Calanus finmarchicus declined during positive NAO
conditions and was replaced by smaller bodied species, apparently less
suitable as food for larval cod.
In the Northwest Atlantic, researchers have suggested a linkage
between oceanographic conditions related to the North Atlantic
Oscillation, abundance of the copepod Calanus finmarchicus, and the
calving success of the endangered right whale in Gulf of Maine.\32\
Abundance of adult Calanus declined with these water mass changes
and a concomitant decline in the birth rate of right whales was
observed. The decline in the calving success comes at a time when other
human impacts such as ship strikes threaten recovery of this species.
These observations suggest that climate-induced changes can have far
reaching ramifications for commercially important fish species
throughout the North Atlantic and for critically endangered marine
These examples of climate-related effects on marine ecosystems are
just a sample from the growing body of evidence linking climate change
to marine ecosystem function. All of these changes, whether trended or
variable over some time scale, may have profound implications for the
health and viability of marine ecosystems and for the human communities
that are dependent upon them. It is our challenge to understand these
linkages both to better predict their effects and to identify the
conservation and management policies in the face of climate variability
and change that may help to mitigate their effects.
Various management authorities have responded. For example, the
Pacific Fisheries Management Council routinely takes into account
decadal-scale changes in marine productivity regimes when setting
harvest policies for Pacific groundfish and other species. Similar
management responses are being used or contemplated in other living
marine resource arenas in which NOAA participates.
Ongoing Challenges for Improving Climate and Ecosystems Information
Marine ecosystems and their component parts have proved to be
sentinels of climate change and ocean variability. Changes in living
marine resources, when observed at proper scales, give us new
information about how changes in climate are affecting the Earth, and
have opened new avenues of research into understanding the importance
of human activities contributing to these observed changes. It is vital
that we improve our understanding of past, current and projected
ecosystem impacts of climate change in order to improve the stewardship
of these resources. Management policies we use in living marine
resource management can either help mitigate or exacerbate changes due
to impacts of climate variation. Below I detail a few of NOAA's
scientific priorities in improving the predictability of ecosystem
responses to climate change.
Regional impacts of climate variability and change are important
and are being studied. In fact, some region-specific modeling predicts
that part of the planet--and the marine environment--will experience
cooler and/or wetter conditions, while other areas will be hotter and
drier. Therefore, regional ecosystem responses may result in stable or
increasing resources in one region while at the same time resulting in
declines in abundance and distribution shifts elsewhere.
Understanding these regional impacts on marine and associated
terrestrial ecosystems will require more detailed regional models and
data linking global climate variations to regional atmospheric and
ocean conditions. This requirement is consistent with NOAA's focus over
the last 5 years to integrate multidisciplinary research at the Large
Marine Ecosystem level. Eight such marine ecosystems have been
recognized in the U.S. Exclusive Economic Zone. It is at the ecosystem
scale where we expect to be able to fully realize how anthropogenic
effects (e.g., fishing, land use practices, pollution) and naturally
driven environmental variation combine to produce the current abundance
levels and composition of species in each of our marine ecosystems.
The following will help improve our understanding the ecosystem
consequences of climate change:
Improved Climate and Ecosystem Modeling
Extreme weather events as well as long term trends in atmospheric
and ocean conditions necessitate that we further improve our predictive
understanding of the climate system and its impacts on ecosystems. To
do so, NOAA believes that expanded Earth and ecosystems modeling could
serve as a tool for studies of: (1) the impacts of climate variability
and change on land ecosystems, ocean ecosystems and carbon cycling; (2)
the strength of ecological and carbon feedbacks on climate (e.g. the
effects of increasing atmospheric carbon dioxide on plant growth, which
in turn affects distributions of atmospheric carbon dioxide); and (3)
improved predictions of the impacts of climate trends on regional large
marine ecosystems and their species. An expanded Earth and ecosystems
model capability would take advantage of the current suite of weather,
air quality, climate variability, and ecosystem models to include
biogeochemical cycling, dynamic vegetation, atmospheric chemistry, and
anthropogenic forcing (e.g. carbon and aerosols) of climate. Existing
hydrodynamic models of ocean circulation would be expanded to include
trophic interactions, primary productivity, and spatial distributions
and movement models for specific taxa, among other ecological
phenomena. It would employ a unified modeling framework, enabling
integration of a comprehensive suite of physics, assimilation,
biogeochemical, and ecosystem model components.
As model development progresses, components will be expanded to
include: (a) a land model (currently under evaluation) that simulates
dynamic land vegetation and land use changes, as well as the exchange
of water and energy between land, vegetation, and atmosphere; (b) a
comprehensive ocean biogeochemical model (under refinement) and (c)
state-of-the-art marine ecological models incorporating ocean
circulation and spatially explicit processes.
Comprehensive Earth-ecosystems models have a wide range of
applicability for managers of marine ecosystems, including:
Short term (6 months to 1 year) and medium term (2-5 year)
projections of the regional response of fisheries and protected
species to climate change
Seasonal-interannual prediction of the abundance and
distribution of marine populations;
Seasonal forecasting of coral bleaching potential and
assessment of the long-term impact of climate variability and
change on coral bleaching frequency;
Assessments of the health of coastal ecosystems under the
stress of pollution and runoff;
Predictions of harmful algal blooms and eutrophication
Identification of impact of climate change on species
Analysis relating to land use practices and climate;
Design of marine protected areas and other management
Predictions of pollution transport and effects on human
Understanding seasonal patterns of plant reproduction and
In order to develop these integrated regional and global models of
ecosystem response, we face a number of technical challenges.
Additional research to provide the information needed to understand the
underlying processes linking climate change to the response of living
marine resources is critical. Many of the examples of ecological
response cited above are based on statistical correlations of time
series of environmental data rather than a fundamental understanding of
the complex relationships responsible for the observed phenomena.
Predictive models must take such complex dynamics into account.
Expanded ecosystem research capabilities will be required to assess
these critical links. At the same time, expanded modeling capabilities
will require more comprehensive physical observations and related
routine monitoring data than we have the capability to deploy today.
Importance of the Integrated Ocean Observing System
NOAA has a large, broad-scale and robust system of oceanographic,
climate, and ecosystem measurement stations throughout the U.S. EEZ and
the world. To make data from these systems available to climate and
ecosystem scientists both within the U.S. and globally, NOAA is working
with other Federal agencies and academic and State partners to build
the U.S. Integrated Ocean Observing System (IOOS). IOOS, when fully
integrated, will provide more complete and improved access to
observations of the oceans, including ecological and physical
parameters linked to climate variability and change and requisite
social and economic information, to serve multiple societal goals. IOOS
will support regional climatologies and will provide information
necessary to model climate impacts on ecosystems at appropriate global,
regional, and local scales. Full development of IOOS is a high priority
in understanding climate effects on U.S. marine ecosystems, and
contributes to U.S. support of the Global Earth Observing System of
Management of Living Marine Resources using Ecosystems Approaches
Our current understanding of climate impacts on marine ecosystems
points to the critical need to employ ecosystem-based approaches to
monitoring, assessing, and managing living marine resources. Climate
change is only one of a complex set of factors (both human-induced and
naturally-occurring), that influence living marine resources. These
include harvesting policies for fisheries, protected species recovery
policies, and management of increasingly complex uses of the coastal
zone for a variety of other societal needs. Effective management of
resources in this complex environment means we will have to balance
many competing and simultaneous objectives. NOAA is committed to
advancing an ecosystem approach to its many stewardship
responsibilities as a way forward in striking this balance. NOAA
defines an ecosystem approach to managing living resources is one that
is geographically specified, collaborative, adaptive, accounts for the
broad scope of ecosystem knowledge and uncertainties, considers
multiple factors affecting resources, is incremental in approach, and
balances diverse societal objectives. Incorporating the effects of
climate change into the conservation of living marine resources is one
of the Nation's greatest and most critical challenges facing ocean
Thank you Mr. Chairman, I would be pleased to answer any questions
you or the other Committee members may have.
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Senator Vitter. Thank you very much, Doctor.
We also have, as I said, Dr. Armstrong. Thank you for being
here, as well, Doctor, and please proceed with your testimony.
STATEMENT OF DR. THOMAS R. ARMSTRONG, PROGRAM
COORDINATOR, EARTH SURFACE DYNAMICS PROGRAM, U.S. GEOLOGICAL
SURVEY, DEPARTMENT OF THE INTERIOR
Dr. Armstrong. OK. Mr. Chairman and members of the
Subcommittee, thank you for the opportunity to participate in
I am Dr. Thomas Armstrong, Program Coordinator for the
Earth Surface Dynamics Program at the U.S. Geological Survey. I
also represent USGS in the Department of the Interior with the
U.S. Climate Change Science Program and the Climate Change
Working Group of the Arctic Monitoring and Assessment Program.
The USGS strives to understand how the Earth works and to
anticipate changes in how the Earth functions. To accomplish
this, USGS science aims to understand the interrelationships
amongst Earth's surface processes, ecological systems, and
human activities. This includes understanding current changes
in the context of prehistoric and recent Earth processes,
distinguishing between natural and human-induced changes, and
recognizing ecological and physical responses to changes in
The scientific community is largely in agreement that human
activity in the 20th and 21st centuries has enhanced greenhouse
gas concentrations in the atmosphere and has affected global
temperature and climate. But climate change is also a natural,
continuous, inevitable Earth process that has occurred
throughout Earth's history. Natural climate change is
influenced by many forces, one of which is concentration of
both naturally-emitted and human-induced greenhouse gases into
the atmosphere. In fact, natural climate change has occurred on
a regular basis on this planet for millions of years.
Paleoclimate research conducted at USGS and elsewhere has
shown that the Earth has experienced several episodes of global
warming in the last 800,000 years, during which air
temperatures and levels of CO2 increased in ways
comparable to present changes. By studying various parameters
or proxies in the prehistoric record, such as tree rings, ice
cores, and fossil records, scientists at USGS and elsewhere
have developed a detailed record of prehistoric climate change,
including changes in temperature and atmospheric CO2
concentrations over the last several hundred-thousand years.
This record shows that natural climate change is generally
cyclical in nature, with 40,000- to 50,000-year-long cycles of
global cooling and glaciation, punctuated by, typically,
10,000-to 15,000-year-long cycles of global warming and
deglaciation, which are often called interglacial periods.
The general consensus among climate scientists is that we
are now in an interglacial period with related global warming.
One of the major challenges facing the climate science
community today is distinguishing natural change from change
imposed upon the natural system through human activities.
Although the prehistoric climate record includes temperature
conditions comparable to those today, ice core records and
other recent scientific findings show that the current
concentrations of CO2 in the atmosphere are now
higher than at any time in human existence or in the
prehistoric record. This trend suggests a significant excursion
from the prehistoric natural climate record that may lead to
unprecedented climatic conditions in the future. A better
understanding of the causes of this change is necessary before
scientists can differentiate between the natural and human-
influenced components of present climate change, as well as the
potential influence of human activities on future global
Understanding the processes and distinguishing natural
variability from human-influenced change is just the first step
toward success in the field of climate change. Equally
important is effectively communicating climate science to the
rest of the world.
Scientists must relay the information, analyses, and, more
importantly, conclusions to policymakers, resource managers,
and the general public in ways that are both easy to understand
and useful. In addition, and very important, scientific
findings related to climate change must be delivered in a
timely manner so that decisionmakers will be informed by the
most relevant, up-to-date, objective information possible.
Furthermore, scientists must provide this information with very
accurate estimates of uncertainty so that conclusions and
recommendations drawn from scientific studies can be properly
The climate science community continues to struggle with
development of a consensus on the specifics of the long-term
climate future for our planet, but, as we continue to conduct
well-planned science to make progress on defining natural
climate change and to better distinguish natural from human-
influenced climate change, we will gain a fuller and more
useful understanding of how climate has changed in the past,
how it occurs today, and how it may occur in the future under
different sets of human-influenced scenarios.
Thank you, Mr. Chairman, for the opportunity to present
this testimony, and I will be pleased to answer any questions
you and the other Members of the Subcommittee may have.
[The prepared statement of Dr. Armstrong follows:]
Prepared Statement of Dr. Thomas R. Armstrong, Program Coordinator,
Earth Surface Dynamics Program, U.S. Geological Survey, Department of
Mr. Chairman and Members of the Subcommittee, thank you for the
opportunity to participate in this hearing on climate change and its
effects on terrestrial and marine systems. My name is Tom Armstrong,
and I am the Program Coordinator for the Earth Surface Dynamics Program
at the U.S. Geological Survey (USGS). I also represent USGS and the
Department of the Interior as a member of the U.S. Climate Change
Science Program and the Climate Change Working Group of the Arctic
Monitoring and Assessment Program.
The USGS strives to understand how the Earth works and to
anticipate changes in how the Earth functions. To accomplish this, USGS
science aims to understand the interrelationships among Earth surface
processes, ecological systems, and human activities. This includes
understanding current changes in the context of pre-historic and recent
Earth processes, distinguishing between natural and human-influenced
changes, and recognizing ecological and physical responses to changes
We conduct scientific research in order to understand the likely
consequences of climate change, especially by studying how climate has
changed in the past and using the past to forecast responses to
shifting climate conditions in the future. My testimony today will
address three major sets of challenges:
1. Distinguishing natural from human-influenced climate change;
2. Understanding ecological and physical responses to climate
change, and predicting the related impacts of these responses
on climate; and
3. Effectively conveying cutting-edge climate science to
policy-makers, decision-makers, and the public.
I will conclude my testimony with a brief discussion of the state
of our understanding of climate science and how this provides a roadmap
to our future understanding of long-term climate change and its impact
on people, natural resources, and the Earth.
Distinguishing Natural from Human-influenced Climate Change
In a statement on behalf of the Administration to the Senate in
July, 2005, Dr. James R. Mahoney, now former Assistant Secretary of
Commerce for Oceans and Atmosphere, and Director of the U.S. Climate
Change Science Program, stated, ``We know that an increase in
greenhouse gases from the use of energy from fossil fuels and other
human activities is associated with the warming of the Earth's
surface.'' This statement underlies the growing public debate on
climate change: are humans and their activities the driving force
behind global warming? The scientific community is largely in agreement
that human activity in the 20th and 21st centuries has enhanced
greenhouse gas concentrations in the atmosphere, and these added gases
have an effect on global temperatures and climate. Climate change is
also a natural, continuous, inevitable Earth process that is influenced
by many forces, one of which is the concentration of both naturally-
emitted and human-induced greenhouse gases in the atmosphere. Many
other forces also control climate change, including cyclical changes in
solar radiation, movement of the Earth's tectonic plates, oscillations
in ocean temperatures and ocean currents, and the positions and
magnitudes of meteorological entities such as high, low, and convergent
zones. In fact, natural climate change has occurred on a regular basis
on this planet for at least the last 800,000 years and possibly much
longer. Paleoclimate research has shown that the Earth has experienced
several episodes of global warming in this timeframe during which air
temperatures and levels of CO2 increased in ways comparable
to the present day changes, although the ice record indicates that the
current concentrations of CO2 in the atmosphere are
unprecedented during human existence. Understanding the science of
natural variability in climate is essential to the formation of
effective policy regarding the mitigation of or adaptation to climate
change, both human and natural.
One of the major challenges facing the climate science community is
distinguishing natural climate change from that imposed upon the
natural system through human activities. This science must also develop
an effective understanding of the consequences of the human-induced
component. The science we conduct in order to understand both the human
component of climate change and its potential impacts on the natural
climate system is known as climatology; paleoclimatology looks into the
prehistoric past of the Earth in order to determine how climate change
occurred prior to human activity. Through paleoclimate studies,
scientists have been able to determine that climate changes naturally,
and that there indeed are natural climate cycles that have occurred
regularly, and in a predictable fashion, over at least the last 800,000
years of Earth history.
By studying various parameters, or proxies, in the prehistoric
record, such as tree-rings, ice-cores, and fossil pollen records,
scientists at USGS and elsewhere have been able to develop a detailed
record of climate change, including changes in temperature and
atmospheric CO2 concentrations over the last several hundred
thousand years (Figure 1). This record shows that natural climate
change predates human influence and is generally cyclical in nature,
with long-term periods of global cooling and glaciation (40,000 to
50,000) years long, punctuated by shorter-term periods of global
warming and deglaciation (10,000 to 15,000 years in duration). The
general consensus among climate scientists is that we are within a new
interglacial period with related global warming.
Ecological and Physical Responses to Climate Change
A second set of very important challenges relates to developing a
better understanding of how the Earth and its physical and biological
processes respond to climate change over the short-term and well into
the Earth's future. Scientific research conducted over the past several
decades reveals that climatic changes are part of a larger interactive
system of changes in ecosystems, oceans, glaciers, atmospheric
chemistry, and many other components. The geologic record provides
information on how this complex system has operated over time and clues
to the potential causes of change. By looking back into the Earth's
geologic record, scientists have been able to determine how ecological
and physical systems and processes change, adapt, or terminate as
climate changes; and how these responses can alter climate (known as a
feedback mechanism). Many of these climate changes are gradual and
continuous, with ecological and physical responses occurring over
hundreds or thousands of years. Some of these climate changes are
abrupt, spanning decades, with the resulting ecological and physical
changes being short-lived but very dramatic.
Some examples of responses and feedbacks to climate change include:
The temperature of the United States has increased by an
average of less than 1 degree Celsius during the past 56 years,
with much variation among regions. For example, Alaska has
experienced an average warming of 4 degrees since 1950, more
than 4 times the U.S. average of 1 degree.
The higher the latitude, the greater the increase in
temperature. Of particular concern are the rapid changes
occurring in northern latitudes, where temperature changes have
been greater than elsewhere on the globe. Permafrost is thawing
and has the potential of releasing significant amounts of
carbon dioxide to the atmosphere and nutrients to the coastal
ocean. Decreasing ice cover is exposing coastlines to rapid
erosion and the Arctic Ocean to accelerated warming. The USGS
and the U.S. Forest Service are initiating a multi-agency,
multi-disciplinary research and monitoring effort to track and
understand these changes in the Yukon River Basin in Alaska and
northwest Canada. The Yukon Basin will serve as a benchmark
landscape for interpreting and responding to rapid climatic,
hydrologic, and ecological changes occurring in Northern
Decreased cloud cover in the northern latitudes related to
climate change correlates to decreased snow levels, less solar
reflection, and thus greater melting of snow, glacial ice and
permafrost. This creates an additional feedback mechanism where
more melting leads to greater atmospheric water vapor, which in
turn leads to a warmer atmosphere.
Over the last 50 years, climate change in the northeast
(Maine and New Hampshire) and mountain-west (Washington and
Oregon) of the United States has led to between 8 and 17
percent declines in annual winter snow pack. The physical
response to this decline includes decreased recharge of the
ground-water systems, decreases in surface-water flows,
increased stress to public water systems, changes in the timing
of river ice-outs, and significant impacts on the spawning
environments for fish such as Pacific and Atlantic salmon.
The Effective Conveyance of Climate Science to Policy-makers, Decision-
makers, and the Public
Scientists must relay relevant information, analyses, and
conclusions to policymakers, resource managers, and the general public
as a whole. Besides global warming, other ecological and physical
consequences of climate change may include strong storms, sea-level
rise, droughts and floods. If scientists can better inform decision-
makers about what to expect from climate change, this will effectively
enhance the development of short- and long-term strategies for
protecting the public welfare and maintaining healthy and viable
ecosystems and natural resources. For instance, studies conducted by
USGS and others are showing that sea-level rise will continue to impact
coastal zones throughout the world. Present and future resource
managers will need to take into consideration this scientific
conclusion when developing an adaptive management strategy for
restoration and long-term stewardship of land, water, and biological
Scientific findings related to climate change must be delivered in
a timely manner so that decision-makers are informed by the most
relevant, up to date, objective information possible. Furthermore,
scientists must provide this information with very accurate estimates
of uncertainty so that conclusions and recommendations drawn from
scientific studies can be properly evaluated. The U.S. Climate Change
Science Program, of which USGS and the Department of the Interior are
members, is actively involved in developing a more effective decision
support strategy for all interested stakeholders.
The Future of Climate Change
Understanding the paleoclimate history--where we look at climate
information well beyond the 50 to 100 year instrumental record--is
important because it provides us a natural climate baseline from which
to work. The instrumental record provides us only a momentary glimpse
of the entire picture of past and future climate change. We need to
understand what has happened in the past in order to forecast future
short- and long-term climate trends. Once the baseline has been
established we can then begin to distinguish the human-induced factors
that must be considered. This information then allows us to validate
model predictions of past climate change and use that information to
develop better-constrained models to forecast the effects of future
climate change, and related ecological and physical responses and
For all of the information we have gathered, and for all of the
understanding of climate change that we have developed, the climate
science community continues to strive toward development of a consensus
on the long-term climate future for our planet. Given our current
scientific understanding of climate change, the following are areas in
which USGS science can make a valuable contribution:
Determining the baseline physical, chemical, and ecological
conditions of the Arctic and Subarctic. Without new baseline
data and monitoring infrastructure, our ability to determine
what changes are occurring in northern latitudes, and our
capacity to help society develop cost-effective adaptations to
those changes, may be greatly diminished.
Developing decision support systems for the impact of sea-
level rise. Current research concludes that sea level rise will
continue. Since sea-level rise is already having impacts on
some ecosystems and human communities, decision support systems
will be critical tools for planners to anticipate levee
construction or relocation of shoreline infrastructure.
Focusing attention on the potential changes in the most
vulnerable regions and systems (e.g., polar regions, coastal
zones, and the tropics), and assessing regional impacts of
long-term climate change.
There might be surprises: critical thresholds in Earth and
biological systems may be abruptly reached that have long-term
or even permanent consequences.
Adaptation strategies can minimize negative impacts of
natural climate change, as well as the impacts of human-induced
climate change; mitigation may work to quell human-induced
climate change and variability.
Although possibly successful, mitigation of natural changes
may very likely lead to unforeseen additional problems unless
the system under study is extremely well understood.
Thank you, Mr. Chairman, for the opportunity to present this
testimony. I will be pleased to answer questions you and other Members
of the Subcommittee might have.
Senator Vitter. Thank you both very much.
I'll open it up with questions, and pose this question to
both of you. Where do 20th century measurements and trends fall
in the very, very long-term historical record, in terms of
previous natural historical cycles?
Dr. Armstrong. Senator, I'll go first.
The current conditions of temperature fit within what we
see in terms of cycles of climate change over the last 400,000
years. We need to look at climate both in terms of long-term
climate change over a long-term many thousands-of-years in
order to distinguish various long-term natural climate cycles,
but also to distinguish those long-term cycles from human-
induced change. But temperature is a component that is on--in
the realm of what we've seen in the prehistoric past.
What is most unique, I think, is that the temperature is
out of alignment with the present CO2 concentrations
and methane concentrations that we see in the atmosphere.
Those, according to the most recent scientific information, are
at unprecedentedly high levels compared to the prehistoric
Senator Vitter. Doctor?
Dr. Murawski. Just look at the shorter time cycle, the last
10,000 year, since the last ice age. The current temperatures
and current amount of precipitation is actually the highest
levels that we've seen in the last thousand years.
Senator Vitter. But that's sort of one cycle. I guess what
I'm asking is, If you look at previous historical cycles,
including peaks, is this--fall within those boundaries, or not?
Dr. Murawski. I agree with the testimony that Dr. Armstrong
gave, in terms of long-term cycling of----
Senator Vitter. Right.
Dr. Murawski.--ice ages that have come and gone.
Senator Vitter. What would be the temperature point or line
beyond which this current trend would clearly be moving beyond
previous historical experience?
Dr. Armstrong. I can get the specific information for you.
But I can say, offhand, that we are--within the
uncertainties that we have from the geological record, we are
on par for being at the peaks of what we've seen in long-term
climate cycles. We are at a peak, in terms of temperature. If
it goes much higher than what we see today, we will be getting
into that realm within the uncertainties of the information we
have in the past, where temperatures will reach unprecedented
levels. But it really--I want to stress, Senator, that it is
the CO2 and the methane levels in the atmosphere
that are significantly higher than what we have seen in the
Senator Vitter. Right. Right. But, of course, one of our
biggest concerns about those levels is impact on temperature.
Dr. Armstrong. Correct.
Senator Vitter. And so, that's why I'm----
Dr. Armstrong. That is correct.
Senator Vitter.--asking about impact on temperature.
Dr. Armstrong. Right. And that is something that USGS
science looks a lot at the past record, and we see that there
is a coincidence between changes in greenhouses gases naturally
emitted, obviously, in the prehistoric record, greenhouse gas
concentrations, and temperature changes. They do mimic each
other. What--if we look at the present scientific literature,
the most recent information from ice core records and other
information, there seems to be a disconnect now between levels
of greenhouse gases, which are going up, compared to what we
see with temperature.
Senator Vitter. OK. Also, another pretty broad question for
both of you. What's each of your opinions regarding the state
of science, in terms of climate models? Obviously, in terms of
your projection to the future and impacts that it could have on
the environment and animals, as well as human populations, we
need to depend on certain models and predictions. What's your
assessment of the current state of the accuracy and fine-tuning
of those models?
Dr. Murawski. We see a convergence of many global climate-
change models that are being run now, and we see a general
convergence in the results. In fact, there was a paper
published in Nature a couple of weeks ago that looked at the
various model runs and looked at their assumptions. And we do
seem to be closing in on the general range of temperature
increases that'll be there.
That being said, we know that we have to do more, in terms
of the modeling, in terms of understanding regional impacts,
because that's what's so important for the ecosystems, both
terrestrial and in the ocean, how the regional climatologies
will influence what goes on, because even the global models
that we have now, are indicating some places will be wetter and
cooler under a general rise in Earth's temperature. And so, we
need to understand and step those models down into the regional
size to understand the regional ecosystem impacts better.
Senator Vitter. And I assume--Doctor, before you answer--I
assume part of this analysis of modeling is how a model
predicts past behavior. And how do they? How do the best models
we have developed to date compare, in terms of predicting past
Dr. Murawski. Well, I'm not a climatologist, so I'll pass
on that one. We can certainly get that information back to you.
Senator Vitter. OK.
Dr. Armstrong. Yes, I would actually like to go back to
what Dr. Murawski was saying about the articles in Nature by
Dr. Overpeck and other scientists. There are several in the
journal, Nature and Science.
One of the global circulation models that was used in this
paper was doing just what you asked, Senator, and that was
looking--using the current model framework and incorporating
the geologic record, the prehistoric record into the model, and
found that, as they put in various parameters from the past
into the framework of this model, including starting conditions
and intermediate and long-term conditions, they were able to
mimic very well the proxy record or the conditions that the--
you would predict, that we know occurred in the past, and then
take that, in turn, and look toward the future. And I would say
that's one of the things at USGS that we--I would have to say
are--have been critical of in the past with research, is that
some of the research hasn't really looked at the natural
variability of systems as effectively as it needed to. And I
think these papers, by Dr. Overpeck and others, are a real
significant breakthrough in the use of the paleorecord in order
to better understand or calibrate to the past to predict into
Senator Vitter. OK.
Dr. Murawski, in your testimony you mentioned, somewhat in
passing, that subsidence in Louisiana, which I'm obviously very
interested in, is attributable to hydrocarbon recovery in
coastal areas. I've talked to some experts down there who also
say that there is long-term natural subsidence unrelated to
more recent activity. Would you like to comment on how you
think those two factors contribute, in terms of subsidence in
coastal Louisiana, in particular?
Dr. Murawski. Sure. There are a lot of factors that are
influencing the rate of sea-level rise there. And, of course,
coastal Louisiana is the hotspot for sea-level rise throughout
the country. Obviously, you've got the issues of the reduction
in sediment coming down the Mississippi and other major rivers,
which are contributing to the marshlands being reduced in size.
You've got all sorts of exploration and production activities
that are creating voids there, that contribute to subsidence.
And then, you've got general sea-level rise. And so, it's the
mix of those three factors that's important. And, of course,
we're trying to mitigate sea-level rise issues in the coastal
marshes down there, because they're so important to the marine
fisheries of the Gulf area, because most of the species there
are estuarine dependent. That means their juvenile nursery
areas are in those marshes, and they're so important.
Senator Vitter. In terms of the relative significance of
the various factors, do you think there is a scientific
consensus about it? Because obviously that drives, in part,
what we might do to stop it or mitigate it.
Dr. Murawski. Well, there has been a lot of work in trying
to look at those relative factors, and they're probably playing
out differently in different locations. Obviously, the
reduction in sediment load in the Mississippi over the last
century has been very significant, in terms of that, but, of
course, you know, in various places the balance of those
factors may play out differently, just because of the nature of
those activities, the very local, you know, exploration
activities, et cetera.
Senator Vitter. OK, thank you.
The Chairman. In terms of looking at the long, long, long
history of the world, what is the--sort of, the period of time
that the cycles have taken place? One of you go back 30- to
40,000 years. How far back do you go, in terms of your
Dr. Armstrong. Well, the science that I was referring to,
Senator, we were looking back over the geologic record 400- to
800,000 years, and obviously the farther back you go, the less
perfect the record, the lower our resolution, and the higher
our uncertainty, which is important to clearly define.
There are different cycles related to different things--
orbital forcing, solar insulation. These cycles occur on time
periods of cycles of 100,000 years, 40,000 years, 17,000 years,
possibly 9,000 years. But these cycles combine to present what
is a very regular cyclical pattern over that long-term
The Chairman. If I understood Dr. Armstrong, if you compare
the current period to the distant past, there still are some
cycles where the highs and lows and the differences would be
similar to what we're--we've gone through in the past. Is that
Dr. Armstrong. That's correct. That's in my written
testimony, as well, at figure 1. Absolutely so.
The Chairman. So, we could--then we could be either at the
top of the cycle and going up, or we could be at the top of the
cycle and starting to turn down.
Dr. Armstrong. The--one of the problems you'll see, even in
figure 1 of my written testimony, is that if we try to
telescope too much the instrumental record, be it 40 years or
100 years, we're looking at a very short period of time in that
long-term climate cycle. It is not much information, in terms
of the long period of time. And without that geologic--that
paleoclimate information, we really can't deduce the long-term
cycle. That's why the ice core analyses, both from west
Antarctica and Greenland, have been so invaluable to us in
understanding long-term climate cycles, because those cycles
are much, much longer than the instrumental record itself.
The Chairman. All right. As you say--if your number-one
challenge is to distinguish natural from human-influenced
climate change, right?
Dr. Armstrong. I believe that is one of our major
The Chairman. What do we need to do to do that job better?
Dr. Armstrong. I think one of the things that we've been
trying to do at the USGS--and I know that other people at NOAA,
with their group on paleoclimate, and academia, are trying to
develop better proxies or better indicators of past climate
conditions, and certainly a better handle on age uncertainties
of the climate record itself, so that we can have a higher
resolved, more accurate understanding of when changes occurred,
exactly, or as close to exactly we can in the geologic record,
and what were the exact conditions that occurred, both in terms
of temperature or gas concentrations or other valuable pieces
of information, including ecological responses to climate
change over the geologic record.
The Chairman. Well, Dr. Akasofu's volcano observatory can
give us a prediction of how soon a volcano may erupt, but we
can't get a prediction over a period of years ahead how often
is that going to happen. Those are natural emissions, right?
Now, do we need any more measurements to determine how much is
natural and how much is manmade on--from the natural side?
Dr. Armstrong. My opinion is, yes, we do. We need more
science that can distinguish--first, truly understand natural
variability, natural climate change, because that baseline is
not static, it is not flat, it is changing. It's constantly
changing. It may not change a lot on a daily basis or over 100
years, but at times it can be abrupt or it can occur
dramatically over 1,000 years. Having more information on that
natural baseline and how it changes and will change over time
is critical to understanding what the additive effects of human
activities are on global climate, and as Dr. Murawski said, on
regional climate, as well.
The Chairman. All right. Dr. Murawski, you're more
connected with the ocean side of this, right?
Dr. Murawski. Right.
The Chairman. Which is two-thirds of the world's surface,
Dr. Murawski. Right.
The Chairman. Do you really think you have the ability to
measure that two-thirds today?
Dr. Murawski. Well, one of our proposals, obviously, is to
try to improve the observing that we're doing in the ocean side
through the Integrated Ocean Observing System and other things.
We're trying to take more and more physical measurements and
correlate them with a more dense biological observing system,
as well. I mean, we're trying to measure things like changes in
walrus distribution and whale distribution in the Bering Sea,
along with the fish species, crab species, and other things.
The Chairman. I'm a fisherman. I think the whales and
mammals go where the fish are, just like we do. But I'll put
What do you think you need, in terms of ability to measure
the oceans, that you don't have?
Dr. Murawski. Well, we need a lot more dense observation
network, in terms of physical measurements--basic buoys, the
sea surface temperatures from satellites. Next generation, we
need the basic tools to measure the biological processes that
we're looking at. They need to be more dense. They need to be
distributed around the coasts. We have a system that's about 50
percent built out at this point, in terms of measuring the
various parameters, both on the physical----
The Chairman. Right.
Dr. Murawski.--side and----
The Chairman. Last question, I'll--I've got a lot more
questions, but I'll only ask one more. I'm sure you're familiar
with what Dr. Sylvia Earl is doing with her submersibles. Are
we learning anything from those submersibles, in terms of
what's happening in the deep sea, as compared to what's
happening on the surface?
Dr. Murawski. Well, in terms of the deep sea, obviously,
you know, this is one of the most unexplored areas on the
planet. Now, we have an ocean exploration project in NOAA that
we've been trying to nip away at, understanding deep coral
reefs and other things. We're learning that, there's a lot more
biological diversity down there than we have anticipated. For
example, the coral gardens off Alaska, in the deep water, were
unknown to science until we started poking around in the deep
water. We definitely need a research program that looks not
only at the coastal ocean, but the deeper ocean, as well.
The Chairman. Well, I've just--I lie a little, that that
was my last question. What's the impact of changes in the deep
sea, as far as human experience, compared to that on the
surface? Is there anything going on down there we should--we
really should be excited about?
Dr. Murawski. Well, one of the things that we need to be
careful about is this new discovery of these deep coral gardens
that we see in the deep oceans. Those deep cold-water corals
are at risk to increasing acidification of the ocean, because
those corals are formed by the accumulation of calcium
carbonate. And if, in fact, the calcium carbonate budget of the
deep ocean is going to decline, particularly in the polar
areas, which some of the projections indicate, then they could
be at risk for long-term climate change.
The Chairman. Well, I have a bill to authorize further
ocean exploration to deal with that kind of research.
Unfortunately, we have a Senator that doesn't want anything
else new authorized, thinks there are too many programs already
authorized. So, we'll probably have to wait until we solve that
Thank you very much, Senator.
Senator Vitter. Thank you, Mr. Chairman.
Senator Lautenberg. Thanks, Mr. Chairman.
I'm sorry I didn't hear all of the testimony that each of
you gave, but I've read through, and I would just like to ask
you, What do each of you think about the widest differences of
view for those who don't see any real alarm out there, as
opposed to those who are--who feel that this is a matter of
great urgency? Are we now being forced to take actions, if I
may use the expression, before it's too late, in terms of the
climate change in--that we're seeing?
Dr. Murawski. As I said in my verbal testimony--and I'm
sorry you weren't here--these factors of increasing
acidification of the ocean, sea-level rise, changes in the
distribution of animals are all sources of concern that we have
to have, in terms of the ecosystem effects of climate change.
Senator Lautenberg. Serious concern.
Dr. Murawski. Certainly.
Senator Lautenberg. Urgent.
Dr. Murawski. The urgency of the issue depends on the
issue, in terms of where we are.
Senator Lautenberg. Well----
Dr. Murawski. We have a number of issues----
Senator Lautenberg.--because we have a debate, an honest
debate among us in the Senate, those who think that, as I said
in my opening remarks, that we're going to endanger our
economy. And I have a comma, and that is, ``if we're still
alive after that.'' And so, you know, the--I'm, kind of, one of
those who could be called an alarmist. The principal reason for
that is, I have ten grandchildren. They're very young. And we
love the outdoors in my family. And it's not simply going for a
swim or fishing. I have a grandchild who has asthma fairly
severely, and we have to be very careful when he over-exercises
or what have you. And now, is the world that we're looking at
going to endanger his health even more? We see a--substantial
rises in the number of juvenile asthmatics and other autoimmune
diseases that are connected to the respiratory well-being. Is
that--might we expect a turnaround in things and suddenly see
the air start to clear up? Or will we be looking at face masks
along the way?
Dr. Murawski. Well, obviously we're concerned about issues
like oceans and human health. That's a new, emerging set of
sciences that we're trying to understand the ramifications of
how changes in ocean systems influence the prevalence of
disease, the relationship of atmospheric issues to ocean
changes, et cetera. And those are obviously areas of emerging
science and emerging interest, in terms of you and others.
Senator Lautenberg. Dr. Armstrong, do you have any comments
about my question?
Dr. Armstrong. Yes, sir. And I am--I'm sorry you missed my
oral--part of my oral testimony----
Senator Lautenberg. I am, too.
Dr. Armstrong.--as well. I think the issue that you're
really getting at here, first and foremost, is the disagreement
on how much of what we're seeing today--and Senator Stevens
said it, we've heard it in testimony--I don't think there's
much disagreement that there is ecological and physical
response to global warming, to climate change. There are
responses. There always have been responses. The question
becomes, What is natural change and response, and what is
human-induced change? And I think the question really becomes,
Can we distinguish between natural climate change or climate
variability and that influenced or induced by human activity?
And that is something that I think we still have a fair amount
of disagreement of, is, How much of each of those components
plays into what we see today? But we recognize that both have a
very large role, and we need more science to really help
distinguish that. But, beyond that, sir, I'd have to say that,
as a scientist, it isn't my job to define urgency or what
mitigation or what policy needs to occur; rather, provide you
with the science you need in order to--you and others--to make
Senator Lautenberg. Well, if we know that human activity
causes a significant part of the changing climate that we see,
are we wise to, instead of trying to balance the scales and see
which comes from where, to get on with that part that we can
deal with and accept some of the natural responses that we get?
Shouldn't we focus on that part, that we know the reduction of
the effects of the human production of problems to the
climate--wouldn't it be a good idea to get going on those
Dr. Armstrong. I agree that in order to mitigate, you need
to understand what you can mitigate. And science can help
provide the information you need in order to understand what it
is that can be mitigated and what are the things that may have
to--we may need to adapt to. But in terms of what those are, I
believe that we just need to provide you with the best, most
relevant science to make those decisions.
Senator Lautenberg. Well, if there's a fire at home, and
you know that it's going to engulf you, and--what you do is,
you immediately respond to getting the fire out, and not try to
just run through the house and find the coolest place. And, you
know, when I see what I think are the irrefutable results of
life as we know it, is that when we look at places like Glacier
National Park and we see that it won't be too long before there
are no more glaciers in Glacier National, or if we see
Kilimanjaro, if we see places in Greenland where shelves of ice
are floating away and leaving something different--and then
Senator Stevens--there are few who are better naturalists than
Senator Stevens, but Alaska is a place with its abundant
beauty, but also there are obviously problems arising. And when
I see what's happened--there was a--and I'm not sure which of
the programs I was watching--the polar bears, and how their
reductions in weight is endangering their existence, and cubs
are born less--in smaller numbers than they used to be--
commonly two or three at a time, now it's barely one at a time,
and the reproduction rate is substantially reduced. When I see
things like that, it--I must confess you, it scares me.
Now, am I correct in saying of the hottest years on record,
19 occurred in the 1980s, or later, and three of the warmest
years on record, average global temperatures, in 1998, 2002,
and 2005? Stop me if I'm incorrect with any of these. 2005 was
the highest annual average temperature worldwide since
instruments--instrumental recordings began, in the late 1800s.
To your knowledge, are those statements correct?
Dr. Murawski. I believe they're accurate.
Dr. Armstrong. Yes.
Senator Lautenberg. Don't know?
Dr. Armstrong. I believe they're accurate.
Senator Lautenberg. They're accurate. Did you say you
Dr. Armstrong. I said I believe they're accurate.
Senator Lautenberg. Oh, OK. Well, the--that tells me that
we've got to get going.
I would ask if any of you have--it's--Mr. Chairman, you've
picked an interesting subject on the--it's one that should
absorb even more attention than we're giving it--have you--
either of you been approached by NOAA scientists who are
concerned that we're not doing enough to address the threat of
Dr. Murawski. I'll take that issue. Obviously, you know, we
have 5,000 scientists in NOAA, and we give scientific opinions
on a lot of different issues. And we have a lot of intense
debate about these issues, in terms of what we're trying to
deal with. Admiral Lautenbacher, who runs the agency, has
expressed to all the staff the importance of having open
debate, in terms of these issues of policy. Our corporate
culture is, trying to make sure that the science is available.
We have an interest in making sure that our science is peer-
reviewed. And so, once it's peer-reviewed, it's generally
available in the public. And, you know, we publish that
science, and we make it widely available within the climate-
change science program and elsewhere. And so, that's our
corporate policy, in terms of dealing with the science that we
Senator Lautenberg. Dr. Armstrong, have you been approached
by anybody from the USGS registering alarm at the pace of our
response to climate change?
Dr. Armstrong. In terms of the pace of conducting our
Senator Lautenberg. Yes.
Dr. Armstrong. No, sir, I have not.
Senator Lautenberg. Oh, everybody--that--they think that
we're moving at the right pace, investing enough resources in
doing that, is that--is that your view?
Dr. Armstrong. I--the scientists who I personally fund and
am responsible for, I believe--we have not had an open
discussion about that, but I can say that they feel that
they're adequately funded to do the work that they have at
hand, yes, sir.
Senator Lautenberg. Dr. Murawski?
Dr. Murawski. I think we have a fair difference of opinion
in our agency, as any individual science would have a
difference of opinion about their research and the importance
of their research. And, obviously, we have to balance what we
can afford with what Congress gives us to do our work.
Senator Lautenberg. Just one last thing, Mr. Chairman.
Do we have obvious examples--and you may have had this in
your testimony--commercially significant fish and shellfish,
their responses to acidification--are these species at risk as
a result of the changing acid levels in ocean waters?
Dr. Murawski. Well, it's interesting, because we had a
similar event about 55 million years ago, in terms of the
Senator Lautenberg. I know I'm old, but I don't remember
Dr. Murawski. Neither do I. And what we saw was rapid loss
of species of plankton that are the base of the food chain. And
so, we're concerned that as acidification rises, that we will
see not only issues with various plankton species, which
support the food web, but also the deep corals, which are
potentially at risk, as well.
Senator Lautenberg. Thanks, Mr. Chairman.
The Chairman. Could I just----
Senator Vitter. Sure. Mr. Chairman?
The Chairman. I don't want to be obtuse, but, Doctor, I had
a briefing from the BLM that located a site in northern Alaska
where there is a promontory that they decided was--I'm sure you
know about it, Dr. Armstrong--a watching place for hunters who
used to hunt dinosaurs----
Dr. Armstrong. Yes.
The Chairman.--and such animals. Now, I don't want to
offend you, but what if, at that period, someone had gotten
alarmed about the rate of change and tried to disturb the
natural occurrence of change? Are we in a similar position?
Dr. Armstrong. Senator, I think that, as I said, if natural
change is inevitable, and it's part of just the Earth's engine
and its processes, then we do need to understand what it is
that we are dealing with. We need to understand, as best we
can, what is natural change, versus human-induced change,
because if we do try to mitigate natural issues, natural change
itself, if we do not understand, in totality, the system in
which that natural change is occurring, there may be unforeseen
complications or other problems that occur due to the
So, my point is not to say that we should not mitigate. My
point is not to say we shouldn't adapt. My point is simply that
the science needs to inform you as to our best understanding
today what is natural change, what do we believe is--based on
the scientific information with the degrees of uncertainty we
have today, what is the human-influenced part of climate
change, so that the people that are really the ones responsible
for mitigation and policy on adaptation can make those
decisions in an informed environment.
The Chairman. Well, thank you. That's my hope, that we'll
concentrate not just on the change that's caused by man, but
concentrate on trying to understand how much of it is natural.
Dr. Murawski. Yes, I'd like to comment on that. I think
we're already starting to see some of our public resource
agencies stepping out on this and trying to accommodate, you
know, changes in the Earth's climate, in terms of the fishery
management, for example. And one good example is, in the
Pacific there is a phenomenon known as the Pacific decadal
oscillation, which is a climatological feature that varies the
climate between Alaska and the Pacific West Coast. The fishery
managers there know that this happens from time to time, and
the productivity of the stocks goes up and down when these
cycles change. And so, what they're trying to do is put in
polices that recognize when these cycles are changing back and
forth, and shift the management accordingly, so that you don't
over-harvest in times when it's poor, or you take advantage of,
when the cycle is actually favorable.
The Chairman. Absolutely. That's what my interest is.
Thank you very much.
Senator Vitter. Just final wrap-up questions.
Dr. Armstrong, I'm really very interested in your figure 1
in your testimony. And, looking at that, one obvious question
that jumps out is, What might the lag time be between CO2
rises and CH4 rises and temperature rises? Is the
past historical record from Antarctic ice cores or anything
else with regard to high temperature periods clear enough to
tell us, in a pretty narrow number of years, which is what
we're experiencing in the 20th century, what that lag might be
so that, you know, we have some beginning of an understanding
of whether the temperature chart is about to spike or not?
Dr. Armstrong. Senator, I will--before I give you my
answer, I'd like to say that I think several of the people,
including Dr. Corell, on the second panel, are outstanding
scientists who ask that very same question, too, and will have
some very--a more accurate estimate for you, or a more
But what I will say is that there is a significant amount
of debate in the scientific literature itself about whether or
not the next--the current interglacial we're in now is one that
will--is similar to the past, in terms of frequency and in
terms of duration. There's a fair amount of debate over that.
There are some scientists who have published recently--in the
past 15 years, that have said that, based on predictions of
orbital forcings and solar insulation, that we may be looking
at a longer interglacial this time than what we've seen in the
last 400,000 years, and that it is, in fact, a unique natural
cycle that we're going into.
I'm not enough of an expert on that field to give you an
opinion on that, but I would say that that, in itself, is
something that we need to look into more specifically, as to
nail down just what will the next 15- to 35,000 years look like
in terms of the natural climate change, and how will, with
increasing greenhouse gases that I think we all agree we're
seeing in the instrumental record--how will those impact
temperature along with the natural cycle over the next 100,000
or tens of thousands of years?
Senator Vitter. What about the very narrow question I posed
about the lag time, if any, between CO2,
CH4, and temperature? Is the historical record, you
know, going back a long time to previous high temperature eras,
precise enough for us to know anything about that?
Dr. Armstrong. I would say that it almost becomes a moot
point, sir, because of the additive effect of the human-
influenced greenhouse gas emissions, that we need to have a
better understanding of what the response will be to the
combined--the additive and the cumulative--effect of natural
and human-induced greenhouse gases. And I will defer to Dr.
Corell on that question. I think you'll get an accurate--a
better understanding of the answer to that question. I do not
have estimates for you.
Senator Vitter. OK. Well, what I'm getting at, I don't
think is a moot point, because it basically goes to whether, at
the end of your figure 1, we're going to experience a spike in
temperature or not.
Dr. Armstrong. I do not have the answer to that question.
That--I didn't mean to infer that that--you know, your question
was a moot----
Senator Vitter. Right.
Dr. Armstrong.--point. It's not. It's a very important
point. And it really need--we need to have a better
understanding from the people that are conducting the models
and forecasting forward, what will be the additive effect in
this case, in this interglacial----
Senator Vitter. Right.
Dr. Armstrong.--which is unique because of the human
activity on this planet. What will be the additive effect to
both greenhouse gas emissions for the future, and, therefore,
the impact on temperature--global temperatures, for the near
future and the long-term future? I do not have the answer to
that question, sir.
Senator Vitter. Thanks. And I'd invite, ahead of time, the
second panel to respond to that question, too.
And, Dr. Murawski, in the Magnuson-Stevens reauthorization,
I've included some authority for restoration work for fish
habitat, particularly with the hurricanes and other events in
mind, that would go through the National Marine Fisheries
Service, through NOAA. Do you have any comment about the
usefulness of that sort of work?
Dr. Murawski. Well, as you know, NOAA is involved in a
number of activities for restoration. There is quite a vigorous
program in Louisiana, in particular, that's--the Army Corps of
Engineers, NOAA, USGS, and the State of Louisiana are involved
in something called CWPPRA. And CWPPRA is quite successful.
This is the Breaux bill. It funds about $55 million a year, in
terms of habitat restoration. And the projects that we're
responsible for in CWPPRA, have been quite successful. In fact,
they negotiated the hurricanes quite well, in terms of the
design of their properties. And we see that coastal restoration
can work in those areas, that we can mitigate against sea-level
loss and loss of those marshes by projects that go through that
sort of process, where we get the best projects, and the
highest priority ones.
Senator Vitter. Great. Thank you all very, very much.
Appreciate your testimony.
Dr. Murawski. Thank you.
Dr. Armstrong. Thank you.
Senator Vitter. I was going to, but, Senator, if you have
any further questions----
Senator Lautenberg. Well, just--at what point is there a
predictability, that's reasonable from evidence that you've
seen in your studies, that says that there is no going back to
the conditions that we've seen before--talking about the
shellfish, talking about what's happening with wetlands as the
flooding takes place and so forth, what happens to those bird
populations or the fish populations that dwell in those areas.
Is it expected that there's always going to be some replacement
for those? I mean, are we--if we're going to be a hot world, is
it likely that we're going to be able to sustain life as we
know it? I mean, one thing we know is that there's going to be
more carbon poured into our atmosphere than there is now.
That's--one doesn't have to be a forecaster for that. Well,
what's that going to do to us?
And I admire your patience, I must tell you, as you search
the scientific routes for knowledge. But I'm an ordinary plain
human being, and I worry about the things that I see in front
of me, about things that change, temperatures changing, the--I
mentioned the polar bears. There are other species that are
under assault as a result of this. We see penguin populations.
I've told you spent time in Antarctica, and went to the South
Pole, and scientists who are working there are very worried
about what's happening.
And, at some point, when do we extinguish the fire before
it totally consumes the forest? And at what point do we work on
these problems that we see in front of us to say there's enough
out there to alarm us, to--for us to say, ``Hey, we're going to
find out more about the natural cycles that can be
anticipated?'' But we know something that we're doing that has
affected it. There's a report by the National Academy of
Sciences that say that the human influence on us is a--the
changes observed--temperature is, in fact, rising. It's--the
changes observed over the last several decades are likely
mostly due to human activities. We can't rule out that some
significant part of these changes are also a reflection of the
natural variability--National Academy of Science, 2001. Do we
dismiss that in the interest of research and say, ``OK, that's
there, but we've got to get on with it, with doing more
research before we dampen the fire? ''
Dr. Murawski. Sir, I think most of the research that we're
trying to do is to try to frame these sets of issues for
people, as yourself, the people who make public policy, in
terms of how we're going to make adjustments or mitigation or
adaptation to these issues. And we're trying to narrow the
bounds of uncertainty, and to try to understand particularly
the regional effects, which will play out in many of the
examples that you talked about.
As to what we do about them, it's a much larger problem
than scientists can actually deliver the information and the
bounds of certainty, but this is in the public-policy arena.
Dr. Armstrong. Sir, one of our----
Senator Lautenberg. Doctor?
Dr. Armstrong.--responsibilities is--at USGS is--being the
science wing of the Department of the Interior, is to provide
science information to our land resource brethren at National
Park Service, Bureau of Land Management, Fish and Wildlife
Service, Bureau of Indian Affairs. And I will tell you that the
problems that you've addressed today are real problems, and
they are things that we are--the response of polar bears, of
seals, of invasive species, of plants and other animals,
especially in climate-sensitive areas, are things that we are
currently addressing and looking into and trying to develop an
understanding of the cause and effect. What causes a polar bear
to lose weight, or what causes a seal population to migrate to
other areas? We're looking at these things now.
And I would actually say to you that it would be
irresponsible of us, as scientists, not to provide you the
information you need and to give you our best professional
judgment. But, in doing that, we need to show you, also, what
degree of certainty and what kind of confidence level can we
give you that information you need to make decisions with. And
that's the thing that we're working on now, is trying to better
understand those cause-and-effect processes.
Senator Vitter. Second panel.
Senator Lautenberg. Yes, OK. So--and I'll wrap up here--I
just--would it be advisable for us to try to reduce
deforestation of our wooded lands? Do they matter? Would it be
wise for you folks to say, ``Hey, listen, cut down on the
amount of carbons that are released into the atmosphere''?
We're--is that a good idea, or is that to be left for another
day or another year, another century?
Dr. Armstrong. I think it's appropriate for the
policymakers and the resource managers to give you that
information that they determine to be appropriate. At USGS,
it's up to us to provide the science to those people that make
Senator Lautenberg. Thank you.
Senator Vitter. Thank you all very much.
Dr. Armstrong. Thank you.
Senator Vitter. And as the second panel is taking the
witness table, I'll begin to introduce our three panelists who
comprise the second panel.
First we'll hear from Dr. Syun-Ichi Akasofu, Director of
the International Arctic Research Center in Fairbanks, Alaska.
And we thank him, again, for traveling such a distance to be
with us. We're also joined by Dr. Robert Corell, Senior Policy
Fellow of the American Meteorological Society and affiliate of
the Washington Advisory Group; and, also, Dr. Paul Reiter,
Professor of the Institut Pasteur, in Paris, France. And we
also thank him for traveling such a long distance.
And as soon as everyone is settled, we'll begin with Dr.
The Chairman. Could I introduce Dr. Akasofu to you?
Senator Vitter. Absolutely, Mr. Chairman.
The Chairman. I just think you should know that Dr. Akasofu
conceived the idea of the Arctic Research Center and obtained
the support of Japan and of Canada and the United States, and,
to a certain extent, of Russia, for the activities that are
conducted there. This is an international center. Substantial
Japanese funds have gone into that, as well as others. And I
think we owe him a debt of gratitude for what he's done,
dedicated a substantial portion of his life to this one area of
Senator Vitter. Absolutely. I agree completely.
STATEMENT OF DR. SYUN-ICHI AKASOFU, DIRECTOR,
INTERNATIONAL ARCTIC RESEARCH CENTER, UNIVERSITY OF ALASKA
Dr. Akasofu. Mr. Chairman and members of the Subcommittee,
I really appreciate, thank you for providing me with the
opportunity to testify at this important hearing today.
The Chairman. Syun, pull the mike toward you, will you?
Pull it right----
Dr. Akasofu. Let's see. As Senator Stevens says, that I am
the Director of the International Arctic Research Center.
Senator Stevens helped us to establish the center. We have been
working on--specifically on climate change.
I would like to summarize my testimony. And the most--the
prominent warming in the world was taking place in the
continental Arctic during the last half of the last century.
So, it--the three times more than the rest of the world. So,
the warming signals are the largest, so we like to concentrate
on that to try to understand it.
The--in the continental Arctic, we have--because of
warming, we have degradation of permafrost--forests and so on,
and many other phenomena.
However, we have at least two firm scientific indicators
that show it is incorrect to conclude that this warming in the
continental Arctic is due entirely to the greenhouse effect
caused by man. The first indicator is that most advanced 14
IPCC global climate models, which includes the best scientific
knowledge of the greenhouse effect, cannot reproduce the
warming of the continental Arctic during last half of the last
century. The IPCC cannot reproduce. This is what we call
hindcasting. We are using last 50 years of data, last IPCC--
best IPCC group to reproduce that. And so, we think it's best
scientific test of the greenhouse hypothesis.
In the scientific methodology, what we do is we make
observation--in this case, global warming. Then we hypothesize
the causes of the warming, the second step. And the last step
is to verify the hypothesis. If necessary, using the
supercomputer. And if computer simulation and observation
agree, then the observations and the--our understanding becomes
But if there is--computer cannot reproduce what we observe,
then the hypothesis has to be disproved. And--but you still
insist that--someone still insists that greenhouse effects is
going, then that belongs to the area of what we call science
fiction, because the science fiction you don't have to rely on
So, then--so, the first test is, we cannot reproduce the
continental warming, which is--as the largest, most prominent
feature of the warming today. The second indicator is that
geographic pattern of the warming in the Arctic has been
drastically changing during the last--in recent years. Strong
continental Arctic warming trend is no longer evident during
the last two decades.
If the warming trend during the last half of the last
century were entirely due to the greenhouse effect, the past
geographic pattern of the warming should intensify, but this is
not the case. Various warming and cooling of similar magnitudes
has continuously occurred at different locations and different
times during the last hundred years. So, it's natural to
conclude that such a trend will continue, as Dr. Armstrong
said, the--both natural and manmade component.
In addition, long-term record of the glaciers and the sea
ice show that they have been--those glaciers and the sea ice
have been receding around about 1,800, well before the CO2
effects became serious. We have some evidence that the present
recession of sea ice in the Arctic Ocean is due partly to the
intrusion of warm North Atlantic water, which is caused by what
we call North Atlantic oscillation, a natural phenomenon, like
El Nino. So, this warm water is now flowing around the Siberian
coast and approaching Alaska.
Also, it's very important to notice that our sun is
changing. The solar physicists have been working on this for
years, and they've found that very important solar output is
So, it is my conclusion that it is urgent to identify both
natural and manmade components of the present warming. So,
results that will be--of--like house-fire example that Senator
mentioned, we are not sure if the house is really on fire. And
to put the water where it would make water damage may be more
That's my testimony.
[The prepared statement of Dr. Akasofu follows:]
Prepared Statement of Dr. Syun-Ichi Akasofu, Director, International
Arctic Research Center, University of Alaska Fairbanks
Thank you for providing me with the opportunity to testify at this
important hearing today.
In order to avoid any misunderstanding, I would like to state at
the outset that it is in the best interests of mankind to reduce the
rate of increase of our release of CO2. My talk is about how
much this future reduction should be. For this purpose, I would like to
1. Prominent climate change is in progress in the Arctic,
compared with the rest of the world. However,
2. arctic climate change consists of both natural change and
the greenhouse effect, and thus
3. it is incorrect to conclude that the present warming in the
Arctic is due entirely to the greenhouse effect caused by man.
4. Therefore, it is important to find out the contribution of
both natural and manmade components to the present climate
change in the Arctic.
The first statement can be illustrated in Figure 1. The range of
temperature change along the coastline of the Arctic Ocean is much
greater than that of the global average. Please note a rapid increase
from 1920 to 1940, a decrease from 1940 to 1970, and a rapid increase
again from 1970 on.
It is also important to note that both the Arctic and global
temperatures began to decrease in about 1940, when our release of
greenhouse gases began to increase rapidly. Thus, the increase-decrease
between 1920 and 1970 must be natural change. One important task we
have is to find out the nature of the warming periods from 1920 to
1940, and from 1970 to the present time. An important question is
whether or not the present rise will continue or whether future
temperatures will decrease, as was the case during 1940 to 1970.
Let us examine where in the Arctic temperature changes occurred
during the last half of the last century. The left-hand side of Figure
2 shows clearly that the most prominent warming was in the continental
Arctic (Siberia, Alaska, and Canada), except in Greenland, where it
The IPCC Arctic Group, consisting of 14 Global Climate Modeling
(GCM) teams headed by V. Kattsov, tried to reproduce the temperature
change for about the same time period on their models. Their results
are shown in the right-hand side of Figure 2. The simulation result
bears no resemblance to the observed, real temperatures in the
continental Arctic. If the simulation were reasonably accurate, the
results should be similar. This is the most quantitative test to date
to examine if the continental arctic warming during the last half of
the last century was caused by the manmade greenhouse effect. This
comparison shows clearly that much of the prominent warming in the
continental Arctic after 1970 was not caused by the human-induced
If, in fact, the continental warming indicated in the right-hand
side of Figure 2 were caused by the greenhouse effect, this trend
should have been intensified during the last few decades. However, that
is not the case. The continental warming in the upper part of Figure 3
(which is similar to the left-hand side of Figure 2) is absent during
the last 20 years (the lower part of Figure 3). Thus, the continuous
increase of the warming is not taking place any more. Instead, intense
warming is now in progress in Greenland, which experienced cooling in
the recent past.
Further, let us examine temperature changes during the last
century. Figure 4 is similar to Figure 1, except it includes the
Subarctic, and the zero line represents the average value of the last
century. One can see that warming and cooling continuously occurred
during the last century. Thus, it is not difficult to infer that the
rise after 1970 is not entirely due to the manmade greenhouse effect.
Fortunately, we now have longer-period ice core data from an island
in the Arctic Ocean. It is shown at the top of Figure 5. The bottom
trace is the reproduction of Figure 1, and the middle one is the
temperature record in northern Norway. All three traces show similar
change from 1900. In addition, the ice core data show clearly that
there are both linear and irregular changes from 1725, well before the
effects of the Industrial Revolution became serious. Thus, it is clear
that the last rise since 1970 is not entirely due to the greenhouse
It is likely that part of the rises and falls of temperature in
1920-1970 can be identified as what is called a ``multi-decadal
change.'' One possible cause of this multi-decadal change is the
changing intensity of the intruding warm North Atlantic water into the
Arctic Ocean (Figure 6), which is associated with a natural phenomenon
called the North Atlantic Oscillation (NAO). At the present, the warm
water is flowing toward the Alaska coast. Studying and tracking this
warm-water pulse, which may be a natural reason for some loss of sea
ice, is one of the major projects of the International Arctic Research
Center (IARC), conducted with the help of the Russian Icebreaker
In recent years, there have been a large number of reports that
both glaciers and sea ice in the Arctic Ocean have been receding.
However, longer-term records show that such phenomena have been in
progress continuously since 1800 or earlier (Figures 7a and 7b), and
are not phenomena that began after 1970. Glaciers in the Glacier Bay
National Park began to recede at least by the time Captain Vancouver
passed by in 1794, and the ice edge in the Norwegian Sea began to
recede in about 1800.
These data show clearly that it is dangerous to infer causes of
climate change using only data that cover the last 40 years or so. In
recent years, there have been a large number of excellent papers that
describe arctic climate change since about 1970. This is because high
quality satellite data became available only after 1970. Fortuitously,
this period also coincides with the beginning of temperature rise
during the last several decades. Thus, all such reports on scientific
results are naturally related to the topic of rising temperatures.
Although I respect the authors of those papers, I cringe somewhat
when the papers are consumed immediately by the media and then the
public. Unfortunately, members of the press often champion these papers
as showing examples of the greenhouse effect, which tends to
sensationalize the results. Thus, the general public often interprets
the results to mean that all climate change in the Arctic must be
caused by the manmade greenhouse effect.
These scientific reports should be treated like any other
scientific papers in professional journals. Any significant conclusions
should be scrutinized by the scientific community before they become
material for public consumption. This requires a certain period of
time. Although I am happy to have the present great public interest in
our research topic of global warming, such instant reporting of results
for relatively short time periods can cause much confusion in the minds
of the public. It is not as simple as stating that ``warming melts
Unfortunately, data gathering for periods before the 1970s is much
more difficult and much more time consuming than obtaining satellite
data. Today, many climatologists tend to avoid dealing with the topic
of climate change before the 1970s. Further, those data may not be of
the quality researchers desire, and some researchers tend to discredit
results based on data before 1970, which is a good excuse to avoid
longer-period data. Therefore, these days there are only a handful of
researchers who deal with climate changes over the last century in
great detail. In fact, it is alarming that only a few researchers in
the world are studying the sharp increase of temperature that occurred
from about 1920 to 1940 and the sharp decrease that occurred from 1940
Our understanding of the change between 1920 and 1970 is crucial
for interpreting the rapid rise from 1970 on and also for future
predictions, because the change between 1920 and 1940 is most likely a
natural one. If computer modeling were adjusted to reproduce the
present rise, assuming that the present rise is due entirely to the
greenhouse effect, its prediction for future years will not be
We tend to forget that some climatologists, who were studying the
temperature decrease from 1940 to 1970, warned the public that a new
Ice Age was just around the corner. Apparently, we have not learned the
lesson of the ``new Ice Age mistake'': short-period data do not tell
the whole story.
In conclusion, the nature of the climate change after 1970 should
be a matter of great debate. It should not be assumed that this short
period of warming is entirely due to the greenhouse effect caused by
the actions of man. The prediction of future trends depends greatly on
the understanding of the nature of the rise after 1970.
Thank you again for the opportunity to present this testimony
today, and thank you for your interest in this important issue. Please
feel free to contact me if you have any additional questions.
ACIA (Arctic Climate Impact Assessment), Cambridge University Press,
Fritzsche, D., R. Schutte, H. Meyer, H. Miller, and F. Wilhelms, T.
Opel, L.M. Savatyugin, Late Holocene ice core record from
Akademii Nauk Ice cap, Severnaya Zemlya, Russian Arctic, in
Papers accepted for publication in Annals 42, International
Symposium on Arctic Glaciology, Geilo, Norway, 23027 August
2006, J.W. Dowdeswell and I.C. Willis, Eds., Annals of
Glaciology, No. 42, A150, 2006.
Hansen, J., L. Nazarenko, Reto Ruedy, Makiko Sato, Josh Willis, Anthony
Del Genio, Dorothy Koch, Andrew Lacis, Ken Lo, Surabi
Menon, Tica Novakov, Judith Perlwitz, Gary Russell, Gavin
A. Schmidt, and Nicholas Tausnev, Earth's energy imbalance:
Confirmation and implications, Science, Vol. 308, no. 5727,
pp. 1431-1435, doi:10.1126/science.1110252, 2005.
IPCC (Intergovernmental Panel on Climate Change), http://www.ipcc.ch.
Polyakov, I., R.V. Bekryaev, G.V. Alekseev, U. Bhatt, R. Colony, M.A.
Johnson, and A.P. Makshtas, Variability and trends of air
temperature and pressure in the maritime Arctic, 1875-2000,
J. Climate, 16(12), 2067-2077, 2003.
Polyakov, I.V., G.V. Alekseev, L.A. Timokhov, U. Bhatt, R.L. Colony,
H.L. Simmons, D. Walsh, J.E. Walsh, and V.F. Zakharov,
Variability of the intermediate Atlantic Water of the
Arctic Ocean, over the last 100 years, J. Climate, 17(23),
Vinje, T. Anomalies and Trends of Sea-Ice Extent and Atmospheric
Circulation in the Nordic Seas during the Period 1864-1998,
J. Climate, 14, 255-267, 2001.
Wiley, S.D., Blue Ice in Motion: the story of Alaska's Glaciers, The
Alaska Natural History Association, 1990.
Senator Vitter. Thank you very much, Doctor.
Dr. Corell, welcome.
STATEMENT OF DR. ROBERT W. CORELL,
SENIOR FELLOW, AMERICAN METEOROLOGICAL SOCIETY;
AFFILIATE, WASHINGTON ADVISORY GROUP;
CHAIR, ARCTIC CLIMATE IMPACT ASSESSMENT
Dr. Corell. Thank you, and good afternoon, Mr. Chairman,
Senator Stevens, Senator Lautenberg, and all gathered here. I
really appreciate the opportunity to join you in this hearing
I'd like to put some context for our discussion, because
there have been significant shifts of the climate in our
planet, with substantial changes and increases in temperature,
particularly during the last 150 years or so, as reported by
Professor Moberg and many others who have documented, as
depicted here, the picture over the last 2,000 years, the so-
called hockey stick. And, as you can see, the instrumental
record is clear that things are happening in the last 150 years
that certainly are unparalleled in the last 2,000 years.
The IPCC third report concludes that while some of the
fluctuations we see--and you can see them here, they are
natural in character--come from natural variability, it is
clear now, to the IPCC any ways, that human influences are
responsible for most of the roughly 1 degree Fahrenheit global
warming that has occurred over the 20th century, and that the
IPCC predicts and suggests that those temperatures, over the
next hundred years, may reach as much as 5 to 9 degrees
First let me say a word or two about the ocean and the
marine setting. A simple and important message, the oceans
control the timing and magnitude of the changes of the climate
system, and do so over decadal timescales. Further, the--any
imbalance of incoming radiation--and we do have an imbalance at
the moment--90 percent of that energy ends up in the ocean. The
10 percent is what we hear about, reducing sea ice, melting
glaciers, warming the atmosphere. So, the oceans are the
dominant player in the situation.
Professor and Dr. Hansen and his group in Columbia have
done an extensive study of the last 10 years of this increased
warming of the ocean, and have concluded that the Earth is now
absorbing about .85, plus or minus a small amount, watts per
square meter. That number doesn't mean anything, but it does
mean the following, and that is, already stored in the ocean is
another .6 degrees, or roughly 1 degree Fahrenheit, of warming
of the planet without any further increase of greenhouse gases
in the atmosphere. So, it's like a supertanker. It stores it,
and it takes a long time for it to play out.
And, in that regard, Mr. Chairman, in answer to your
question, at least when we're combining warming that's due to
both natural and anthropogenic factors, it's clear that there
is a lead-lag relationship, that, as CO2 goes up and
the warming takes place of the ocean, it will take a somewhat
longer time for that to be expressed as a warming of the
This oceanic warming has a wide range of impacts, both
physically and biologically. The first is that there's a long-
term effect on sea level, which I'll come back to. As the heat
is propagated downward into the ocean, we're only heating the
upper few hundred meters already, and we have 4,000 meters to
go. And as that heat propagates down, the oceans expand, and
sea level will continue to rise. And I should note that most of
the sea-level rise that we've experienced to date has come from
this thermal expansion of the ocean, and not from land-based
As Dr. Murawski has indicated, there certainly is a clear
impact on fisheries, marine mammals, sea birds, and other
marine life, and it will have a significant change in the
future. The shift in fisheries have already been observed, and
will continue to occur as both oceanic temperatures and
currents shift. Marine mammals, including walrus, sea whale,
seals, and polar bears, are already being impacted, as Senator
Lautenberg aptly pointed out.
While the ocean, as a whole, can store vast amounts of
CO2, it's not very well mixed, and much of that
absorption of CO2 builds up near the surface. And
this has the effect of altering the oceanic chemistry and
resulting in increased acidity of the ocean, which has already
been noted by previous testimony.
What I'd like to note here is that as the CO2 in
the atmosphere increases from our present level, about 380 or
so parts per million, up toward the 6-700 region, laboratory
experiments on the calcification process of plankton strongly
indicate that these animals--or these plants at the lower end
of the food chain will have a very difficult time forming. And
you can see the difference between the lower left and the lower
right. So, the acidification will play a profound role, and the
impact in the whole life chain in the oceanic region.
The extent of summer sea ice has already been reduced by
about 20 percent in the past 20 years or so, and the Northern
Sea route is already opening up along the Russian coast, which
will, in the end, open up seaways that are about 45 percent
closer in time between the two markets of the Far East and
What are some of the impacts in the terrestrial biosphere?
Changes in CO2 itself will have an effect on the
terrestrial biosphere. As a result, higher concentrations will
lead to greater carbon uptake by plants. Storage in the plant
material will increase as long as the soils have adequate
nutrients, such as nitrogen, to support it. Food production
will likely increase in the short term, or at least until
concentration gets sufficiently high that--where other factors
will start limiting their productivity.
So, for natural systems in forests and grasslands, the
situation is likely to be even more problematic than it is in
the agricultural region. Each ecosystem has a preferred set of
conditions, relationships between each element in the system.
And as the climate shifts some range--some ecosystem elements
can move slowly, some move fastly. And, therefore, the out-year
composition of those ecosystems is likely to be quite different
than they are now.
The temperature increases that we've already experienced in
Alaska since 1970 in the Kenai peninsula have indicated how
disastrous those modest temperature increases can have, because
the over-wintering of the spark--the spruce bark beetle has
already led to sudden and really widespread loss of the white
Finally, the projected increase in frequency of droughts,
wildfires, floods, and other extremes, such as hurricanes, are
the kind of thing that we can expect to have impact not only on
our ecosystems, but on our society as a whole. And because
these projected changes are evident in the frequency of the
events, the timing and the intensity, and the localization of
some of the participation, all sorts of challenges lie ahead,
some of which we have ability to see, others of which will
require continued research, and one of the most important of
which is the status of freshwater reserves around the planet.
Now, in the Arctic, the melting of snow cover and the
river-ice permafrost combined with the loss of sea ice has had,
and will continue to have, a really profound effect on
wildlife, particularly on its movement across the regions.
Warmer species--warming conditions have already resulted in new
species. If you go to the Inuits, in the north of Canada, the
word ``robin'' doesn't exist in their vocabulary or in their
language, and robins are now prolific in those regions.
As a result of these kinds of changes across the U.S. and
also around the world, conditions such as heat waves, drought
conditions, will be more favorable to propagate wildfires, as
Alaska has experienced one of the most incredible wildfires a
couple of years ago, of 600--6.5 million acres destroyed in one
On the other side of the precipitation question, there is
going to be more intense----
Senator Vitter. Doctor, if you could start to sum up, I
Dr. Corell. I would--surely. There will be more intense
rainfall, which will result in more flooding.
I want to say a word or two about Greenland. The ice
melting there is pretty dramatic, as you can see in these
images. And there has been a melt of about 20 percent increase
just in the past 25 years, and last year the melt region was
the largest in recorded history.
Sea-level rise will have an impact, such as 1 meter of sea-
level rise on Florida, as indicated in this diagram here; and
elsewhere around the planet, even more profound implications.
I was just recently in Alaska to visit Shishmaref, which is
a very important village to the Alaskans, and the picture in
the lower right--lower left-hand corner was taken only a couple
of weeks ago. It resulted from a storm last fall, that the sea
ice used to protect that shoreline, and the sea ice is no
longer there to do so. And, as a consequence, the village is
going to have to move, at very costly levels.
So, the Arctic now is really experiencing some of the most
rapid and severe changes, and it's going to be that way in the
Let me just summarize by saying that the Arctic is one of
the most important regions to note what's happening. As Senator
Stevens said, it's the bellwether, it's the place in which we
will see the most change most rapidly, and it is a part of our
And while it's clear to me that global change is here,
we've got a major task ahead of us. I urge all of us to join
together in giving this serious attention to look at
assessments as a vehicle by which science can communicate its
knowledge at global, regional, and national levels to
policymakers like yourself.
Thank you for your attention and your time.
[The prepared statement of Dr. Corell follows:]
Prepared Statement of Dr. Robert W. Corell,\1\ Senior Fellow, American
Meteorological Society; Affiliate, Washington Advisory Group; Chair,
Arctic Climate Impact Assessment
Mr. Chairman, Members of the Subcommittee, and all gathered here
today, I thank you for the opportunity to participate in today's
hearing on the ``Projected and Past Effects of Climate Change: A Focus
on Marine and Terrestrial Systems.'' I am honored to join you to
explain the science that underpins understanding of the past and
projected effects of climate change, especially in terms of the impacts
on marine and terrestrial systems in North America, across the Arctic
region, and around the world.
In offering these perspectives, I will be drawing primarily from
the findings of major scientific assessments, a number of which I have
been involved with, because these assessments very thoughtfully draw
together the collective findings of the scientific community. These
assessments deserve very high and special consideration because their
credibility has been well established as a result of their extensive
open review processes, which have helped to carefully hone their
At the national level, I will be drawing upon the results of the
U.S. National Assessment that was completed 5 years ago.\2\ In my role
from 1990-1999 as chair of the Subcommittee on Global Change Research
that directed the U.S. Global Change Research Program, I was
instrumental in the organization of this assessment, and after I left
government service I served on the National Assessment Synthesis Team
that summarized the assessment's findings. In describing potential
consequences for the Arctic, I will be drawing mainly from the results
of the Arctic Climate Impact Assessment (ACIA), which was completed in
2004,\3\ having been established and charged to conduct the assessment
by the Arctic Council \4\ and the International Arctic Sciences
Committee.\5\ For ACIA, I served as chair, leading an international
team of over 300 scientists, other experts, and elders and other
insightful indigenous residents of the Arctic region in preparing a
comprehensive analysis of the impacts and consequences of climate
variability and changes across the Arctic region. At the international
level, I will be drawing mainly from the results of the
Intergovernmental Panel on Climate Change (IPCC), which I was
instrumental in helping to conceive in the late 1980s in my role as
Assistant Director for Geosciences at the National Science Foundation
(NSF) from 1987-1999. The IPCC's members are the nations of the world
and the periodic assessments that they commission represent the
collective evaluation of scientific understanding by the international
scientific community. That the IPCC's assessments of 1990, 1995, and
2001 have been unanimously accepted by the world's community of nations
gives a strong indication of the widespread agreement that exists
regarding the major finding that human-induced climate change is
already influencing the climate and the environment and that much
larger changes lie ahead.\6\ For more detailed information and
scientific citations on most of my points, reference should be made to
the cited assessments. In areas where the pace of research has been
especially rapid or significant in recent years, however, I will also
be drawing upon the results of more recent scientific articles, which I
will specifically reference.
Context for Today's Hearing
The IPCC's Third Assessment Report \7\ summarized the peer-reviewed
scientific evidence that human activities, in particular the ongoing
emissions of carbon dioxide (CO2) and other greenhouse gases
to the atmosphere resulting primarily from the combustion of coal, oil,
and natural gas, are causing the Earth's climate to warm more rapidly
and persistently than at any time since the beginning of civilization.
While some of the fluctuations are likely a result of natural factors
(e.g., variations in solar irradiance and major volcanic eruptions),
the IPCC evaluation concluded that the strength and patterns of these
change makes clear that human influences are responsible for most of
the roughly 0.6+C (1+F) warming during the 20th century. In particular,
despite the cooling influence of the 20th century's largest volcanic
eruption in 1991, the fifteen warmest years in the instrumental
temperature record available since 1860 have all occurred in the last
25 years,\8\ and comparison with paleoclimatic reconstructions \9\ of
temperatures over the last two thousand years indicates that recent
warmth is unprecedented, at least for the Northern Hemisphere where
paleoclimatic data are most available.\10\ In addition to the warming
of the surface, which has been particularly strong in the Arctic,\11\
warming is also evident in ocean temperatures (causing some of the sea
level rise), below ground temperatures, and temperatures well up in the
troposphere.\12\ Other evidence of climate change includes diminishing
sea ice and snow cover in the Northern Hemisphere, melting back of
mountain glaciers in the tropics and in most other locations around the
world, and an increasing tendency for precipitation to occur in
relatively heavy amounts.
For the future, IPCC projects that significantly greater warming
lies ahead. Considering a wide range of possible scenarios for how
human activities (e.g., changes in population, technological
development, energy use and supply, economic development, and
international cooperation) are likely to alter atmospheric composition
during the 21st century, the IPCC projects a further increase in
average annual surface air temperature around the globe of roughly 1-
2+C (1.8-3.6+F) from 1990 to 2050 and a further 1-2.5+C (1.8-4.5+F) by
2100, bringing the projection for total human influence from the start
of the Industrial Revolution to 2100 to roughly 2.5-5+C (about 4.5-
9+F).\13\ As is the case for the warming over the 20th century, future
changes are expected to be greater over land than over the ocean,
greater in mid- to high latitudes than in low latitudes, and, except
where regions really dry out, greater during the winter than during the
summer and greater during nighttime than daytime. As will be explained
more fully in discussing likely impacts, many other aspects of the
world's weather and climate will also be affected.
That such changes in the climate will occur as a result of human
activities is no longer scientifically controversial. During the rest
of my testimony, I will discuss what the likely consequences of the
changes in atmospheric composition and climate are likely to be for the
environment, focusing on three specific domains:
Oceans and marine systems;
The terrestrial biosphere; and
The interface between the marine and terrestrial
My discussion will focus on the links between climate change and
these systems. It is important to recognize, however, that a number of
additional stresses are affecting each of these environments, including
air pollution, nitrogen deposition, toxics such as mercury,
unsustainable extraction of resources, over-fishing, nutrient-induced
eutrophication, depletion of stratospheric ozone and UV enhancement,
etc. Climate change is thus only one aspect of global environmental
change, although a continuously accumulating one that over time will
have very large impacts, and for a full evaluation of likely
environmental consequences for both marine and terrestrial
environments, comprehensive research and assessment efforts are
Interactions and Impacts Linking Climate Change and the Ocean and
Oceans cover about 70 percent of the Earth's surface. Because of
their large heat capacity, the oceans moderate climatic swings by
supplying heat to the atmosphere and adjacent continents during the
winter and, because they warm relatively slowly during the summer, are
the source of cooling sea breezes during times of peak solar radiation.
Much of the heat absorbed by the oceans goes into evaporating water,
providing the moisture that supplies vital precipitation for land areas
via the monsoons and tropical and extratropical storms. These rains and
associated geochemical interactions help to cleanse the atmosphere of
pollution. In addition, oceans support a wide diversity of biological
life that supplies fish, birds, marine mammals and other species higher
in the food chain, and supports the fisheries that in turn provide
substantial food for humans.
While the oceans seem so large that it is hard to imagine that
human activities could affect them, records over geological time and
observations of recent changes make clear that both the physical and
biological systems in the ocean are quite sensitive to changes, and,
indeed, are being affected. The very human activities that are causing
the climate to change are becoming the major influence on the oceans.
First, the oceans affect atmospheric chemistry. In their natural
state, cold waters forced to the surface by wind patterns in low
latitudes release large amounts of CO2 to the atmosphere as
they warm. Before humans started altering the carbon cycle, roughly the
same amount was taken up in mid- to high latitude ocean areas as the
ocean waters cooled and marine organisms grew, died and sank to the
ocean depths. With this balance, which was modified somewhat during
glacial periods when the oceans were colder, the atmospheric CO2
concentration has been held in the range of about 180 to 300 ppmv \14\
for the past several million years. As human activities began to emit
large amounts of CO2 as a result of combustion of coal, oil,
and natural gas, the atmospheric concentration has been driven higher
because the oceans and living biosphere cannot absorb it all. On time
scales of years to centuries, the oceans take up about a third of the
emitted amount, limiting the atmospheric buildup and thus moderating
the pace of climate change.
While the oceans as a whole can hold vast amounts of dissolved
CO2, the oceans are not well mixed vertically, and so most
of the added CO2 builds up in the near surface layer. This
has the effect of altering oceanic chemistry, most importantly by
making the ocean more acidic.\15\ Increasing oceanic acidity has a
range of effects, but the most important is that it makes it chemically
more difficult for marine organisms to form shells. For corals, the
rise in the CO2 concentration from its preindustrial value
of about 280 ppmv to its present value of 380 ppmv has already caused a
significant shrinkage in the regions most favorable for reef-forming,
and by 2050, virtually all of the most favorable regions in the world
will have disappeared, simply due to the rise in the CO2
Adding in the sensitivity of corals to warmer ocean waters (the
``coral bleaching'' effect), the prospect for more powerful storms and
wave conditions, the increasing threats from coastal runoff and fish-
harvesting, and other stresses, the prospects for many of the world's
reefs are very problematic. While the potential impacts on coral are of
most immediate concern, impacts on other shell-forming organisms are
also likely to become significant over coming decades, particularly as
the CO2 level approaches 750 ppmv.\17\
As the rising concentrations of CO2 and other greenhouse
gases have trapped more infrared radiation, making it more difficult
for the Earth's surface to cool, most of the additional heat has been
taken up by the oceans because they are capable of mixing it through
the upper hundred meters (yards) or so of ocean depth. Surveys of ocean
temperature give a clear indication that the ocean's upper layers are
warming; \18\ indeed, the warming that is being observed is in good
agreement with climate model simulations of how the oceans are being
projected to warm as a results of the changes in atmospheric
This oceanic heating is having a wide range of both physical and
biologically important impacts. Because the oceans are able to mix the
heat downward, they are able to slow the warming of the atmosphere,
which is beneficial, but it also means that we are not experiencing the
full extent of warming to which past emissions of CO2 have
committed the world. Experiments with climate models indicate, for
example, that the world would be committed to further warming of about
0.5+C (almost 1+F) even if global emissions of CO2 were to
be quickly cut to near zero.
Warming of the oceans also makes more energy available to the
atmosphere if just the right conditions prevail. For example, warm
ocean waters provide the energy needed to intensify tropical cyclones
(i.e., hurricanes and typhoons), and indeed, recent studies \20\ are
finding that increasing sea surface temperatures are leading to an
increasing proportion of tropical cyclones to be in the most powerful
and destructive categories (more on the consequences of more powerful
tropical cyclones in the section dealing with the ocean-land
interface). While there has been significant debate recently about
whether the available record provides a definitive indication of this
linkage, a paper in press in the Bulletin of the American
Meteorological Society, of which I am a co-author, finds that there are
many reasons to suggest that there is indeed a strong linkage and that
it may well be limitations in our detective work that are the
problem.\21\ If this is indeed the case, and it seems quite likely,
then the world faces a situation where the storm season is becoming
longer, storms may well last longer, and the likelihood of relatively
intense storms is increasing, likely leading to greater and greater
destruction and loss of life unless our adaptive efforts \22\ are
Climate change also has the potential to influence the pattern and
character of the normal year-to-year fluctuations of the climate. For
the Pacific region and then for much of the U.S., the natural variation
of the El Nino-Southern Oscillation (ENSO) is of critical importance,
variously causing El Nino and La Nina events (i.e., unusual warming or
cooling in the eastern tropical Pacific, respectively) that redirect
the Northern Hemisphere jet stream, thereby creating either quite wet
or quite dry winter conditions across various parts of the U.S. (e.g.,
this year, the ocean conditions are causing the U.S. West Coast to be
inundated with very large amounts of rain). Research to date only hints
at how ENSO may be affected, with some indication that the overall
conditions may become more El Nino-like with more intense El Nino
events (meaning, for example, more winter precipitation for California,
increasing flooding potential in the spring and increasing the stock of
burnable vegetation). However, there remains significant disagreement
among model results and this area is, therefore, being investigated
intensively by various research groups.
Changes in atmospheric winds and weather (a result of the warming)
and increasing ocean temperatures (which also feed back to affect the
weather) also lead to changes in ocean currents. Under normal
conditions, warm ocean waters are pulled poleward to replace cold
waters that sink to the ocean depths in high latitudes. As these waters
are pulled poleward, for example in the Gulf Stream, heat is given off
that tends to keep Europe relatively warm in winter, given its
latitude. As climate change prevents ocean waters in high latitudes
from cooling as much, the rate of sinking waters declines, and so less
warm water is pulled poleward, providing less winter heat. While this
slows the human-induced warming rate in Europe, it leaves that heat in
lower latitudes, causing those regions to be warmer and even more
moisture to evaporate, moisture that is likely to result in more
intense rainfall events. Slowing the generation of oceanic deep water
also slows the transport of dissolved CO2 into the deep
ocean, releasing somewhat the oceanic brake on the pace of global
Fisheries, marine mammals, seabirds, and other marine life will all
be significantly affected by these changes. Both the increasing
temperature and freshening of upper ocean waters in some regions by
increased precipitation will tend to increase stratification of the
upper ocean, affecting the vertical distribution and productivity of
biological activity.\23\ Shifts in fisheries will occur (and some
changes are already being observed) as ocean temperatures shift and
changes in abundance will occur as the amounts of upwelling nutrients
and associated biological activity are reduced. The retreat of sea ice
will also lead to changes in fisheries, as the ice edge is normally a
very productive site as a result of the release of nutrients from the
melting ice and the protection from intense waves provided by the ice
itself. Marine mammals, including walrus, seals, and polar bears,
depend on the presence of sea ice to raise their young and to hunt for
food, and the retreat of ice is already having a significant
impact.\24\ The shifts in ocean conditions, both of sea ice and of
biological activity, are also starting to have effects on sea birds,
which are also facing increasing competitive pressures from birds that
normally are shifting northward as warming increases.
An added result of sea ice retreat will be the potential for
greater access by ships. The melting back of sea ice is already near to
opening the Northern Sea Route that would connect the Atlantic and
Pacific Oceans via open water north of Eurasia. Not only would such a
route cut shipping time significantly, but the route will also increase
seasonal access to arctic resources, both below coastal waters and on
land (although, perversely, the summer melting of the permafrost will
make transport over land much more difficult). Already the Northwest
Passage is becoming navigable for icebreakers and in the decades ahead
greater access should be possible. Environmentally, such access will
greatly increase the risk of contamination from spills and other
pollution, and there is virtually no experience or effective approach
for cleaning up such spills. Politically, the increased access is
already raising questions of sovereignty, ownership of coastal zone
resources, and rights to the shifting fisheries that will result. The
identification of such issues as part of the Arctic Climate Impact
Assessment formed the basis of the policy guidance document that was
prepared by the Arctic nations as a framework for future
Overall, human-induced climate change is thus already having
significant effects on the ocean, the weather systems that the ocean
generates, and on the biological systems that are dependent on its
resources. Adding on the impacts of sea level rise on the coastal
environment, which is treated below, the global oceanic environment on
which we all depend is already screaming, at least in a figurative
sense, for actions to greatly slow the pace of change, especially as
roughly an equal amount of change as has already occurred is almost
certain to result as a consequence of past human activities.
Interactions and Impacts Linking Climate Change and the Terrestrial
Changes in both the CO2 concentration itself and in the
climate will affect terrestrial systems. Because CO2 is
needed by plants to grow, the increase in its concentration will, as a
whole, enhance plant growth and allow the stomata (pore openings) on
the undersides of leaves to open less, allowing less harmful air
pollution in and less moisture out, thereby improving the overall
health and water use efficiency of plants. As a general result, the
higher CO2 concentration will thus lead to greater carbon
uptake and enhanced storage as plant material and in soils as long as
nutrients and sufficient soil moisture are available. Recent studies
suggest that the CO2 fertilization effect will be limited by
tropospheric ozone concentrations \26\ as well as the availability of
nitrogen in ecosystems.\27\
However, different plants respond quite differently. Under
conditions with adequate moisture and nutrients, many types of crops
(key exceptions are maize, millet, sorghum, and sugar cane) respond
quite strongly to the increase in the CO2 concentration, but
then so too do many weedy plants, necessitating additional control
measures. Assuming that farmers can overcome problems with weeds and
increased occurrence of pests and that moisture amounts are sufficient,
the per acre yield of many food crops is likely to increase by tens of
percent.\28\ It is for this reason that the IPCC and other assessments
suggest that overall global food production will increase, at least
until the CO2 concentration gets much higher when the effect
can saturate or even changeover (i.e., become essentially toxic).
Simple economic analysis would then suggest that with more agricultural
production, food prices will drop and that there will be sufficient
food, at least for those who can afford it, providing a net economic
benefit to society. However, the situation in the real world is a good
bit more complex. In the U.S., for example, overproduction currently
leads to the need for subsidies as a result of overproduction, and so
an increase in productivity and a decrease in commodity prices may well
lead to calls for larger subsidies. With the climate also changing,
there will also be a constant need to adjust seed strains to ensure
optimal productivity,\29\ creating greater needs for support of crop
development programs at, for example, the land grant universities.
In addition, while productivity will go up in both good and
marginal farming areas, the increase will be greater in absolute amount
in the better farming areas, and so the economics of farming in
marginal areas is likely to worsen, leading potentially to the
abandonment of farming in such areas unless a switch can be made to
other crops for which there is demand (e.g., a non-food crop that can
be used to produce biofuels). For those now growing niche crops (e.g.,
crops such as apples and broccoli in cool summer regions such as
upstate New York and New England; tomatoes in regions where nighttime
temperatures are cool enough for fruit to set; etc.), warming is likely
to make such regions uncompetitive for continued production of these
crops. Because soils are typically not fertile enough to compete
economically with regions now growing warm season crops, farming in
such regions is also likely to be threatened. Thus, while overall food
production in regions such as the U.S. is projected to increase, there
are likely to be hard times for many farmers (and the rural communities
associated with them) as adjustments occur. Lost in the transformation
is likely to be the effective role present-day farmers play in caring
for the land, which is likely to create ecological challenges because
returning such regions as the southern Great Plains to their pre-
farming vegetation is unlikely to be successful due to the altered
For natural systems such as forests and grasslands, the situation
is more problematic. Each ecosystem type has a set of preferred
conditions, as is evident from the changing distributions of types of
forest ecosystems going poleward or up a mountain. As climatic
conditions shift, the preferred ranges for each type of ecosystem will
shift, and numerical models that simulate this process indicate that
the projected changes in climate over the 21st century will have
profound effects. Starting from the Arctic (and focusing on the
coarsest subdivision of ecosystem types), the tundra, which is summer
home and nesting ground for many migrating birds and mammals, will be
squeezed against the Arctic Ocean as the boreal forest becomes
established further and further to the north. Across the United States
and Canada, temperate forests and grasslands will push northward, with
the northeast mixed forest giving way to more temperate vegetation and
with forests giving way to savanna and grasslands in regions where
precipitation does not increase enough to supply the needed moisture in
the face of rising temperatures. For the southeastern and southwestern
U.S., this balance will be particularly important. As described in the
U.S. National Assessment, if the summertime conditions become warmer
and moister, the southeastern mixed forest can persist, but if
precipitation does not increase sufficiently, the soils will dry and
the temperatures will increase even more, creating a situation where
more frequent fires become likely to accelerate the transition to a
sparser savanna woodland situation.\30\ In the southwestern United
States, increased precipitation, particularly in the winter, may be
sufficient to increase biological productivity in desert areas,
allowing greater vegetation growth in winter. While seemingly
beneficial, if summers become hotter and remain dry, the potential for
increased fire is significant (e.g., increased wintertime growth of
chaparral would likely only increase the likelihood of periodic fires,
which can be particularly threatening to communities in the West).\31\
While adapting to a situation of relatively slowly shifting
ecosystems on the continental scale may seem comparable to adapting to
the reforestation of the Northeast over the 20th century, the actual
situation on the local scale, both for wildlife and for communities, is
likely to be much more challenging. This is the case because there are
significant variations in the response of the different plant species
that make up the ecosystems to the changes in CO2 and
climate, and this will mean that the preferred ranges of different
species will shift by different amounts and at different rates, thus
pulling apart current ecosystems without there becoming stable climatic
conditions in which new ecosystems can evolve--instead, everything will
be changing at once.
Determining the thresholds that might lead to abrupt changes in the
functioning of natural systems is, however, particularly difficult, and
there are likely to be thresholds or tipping points that initiate a
sequence of changes beyond which systems are likely to collapse. For
example, a temperature increase of about 1+C per decade since 1970 in
the Kenai Peninsula in Alaska has caused permafrost melting and allowed
the over-wintering of spruce bark beetles and the influx of additional
disease vectors, weakening the trees, and enhancing the extent and
intensity of wildfire. Together, these effects have led to the sudden
and widespread loss of the white spruce forest, and to a situation in
which, even were the new climatic conditions stable, it would take
centuries for new species to develop into a new, fully mature
ecosystem; with stable conditions not likely for at least many decades,
development of a new, mature forest system is likely far off in the
future. As another example of the sensitivity of extant ecosystems, a
massive die-off of pinyon pine (Pinus edulis) covering 12,000 square
kilometers in the southwestern United States was observed during the
recent severe drought. Although the soil moisture deficit was no worse
than the one endured in the 1950s, the higher average temperature
appears to have combined with the extreme dryness to make the trees
more vulnerable to attacks from bark beetles.\32\
Increased frequency of droughts, wildfires, floods, and other
extremes, including greater damage from increased and more persistent
winds and precipitation from tropical cyclones,\33\ are other types of
changes that have the potential to exceed the adaptive capacity of
existing ecosystems. In addition, more frequent fires and the reduced
productivity of some ecosystems will limit the amount of carbon being
taken up and stored by the biosphere, thus leaving a larger fraction of
the emitted CO2 to exacerbate global warming. For example,
the recent Indonesian fires driven by ENSO drying and human land use
changes led to significant releases of CO2 to the
atmosphere. A recent international comparison of coupled carbon climate
simulations \34\ found that all of the models projected some
destabilization of tropical ecosystems, leading to soil drying, reduced
plant/tree growth, and increased occurrence of fire and net emission of
CO2 to the atmosphere, thereby accelerating warming
(positive feedback loop).\35\ Models typically suggested that by 2100
these ``carbon-climate'' feedbacks would lead to the atmospheric
CO2 concentration being higher by 20 to 200 ppmv \36\ and
additional warming of 0.1 to 1.5+C, with the worst-case model scenario
projecting the complete die off of the Amazon rain forest. These
feedbacks are not yet well understood or represented, requiring coupled
treatment of climate change, CO2 fertilization, nitrogen
limitation, and the ability of trees to tap deep soil horizon water;
however, these processes do indicate the potential for the likely
outcome being more toward the upper end of the IPCC range of
Because projected shifts in the frequency, timing, intensity, and
location of precipitation will lead to all sorts of challenges, issues
relating to freshwater resources, although of a variety of types, were
a common thread across all regions in the U.S. National Assessment (see
Table 1 for a brief summary of key regional consequences). For example,
the increased likelihood of additional wintertime precipitation in the
western U.S., as projected in both models used in the U.S. National
Assessment, increases the potential for mudslides and high river levels
as well as increasing the likelihood of mountain precipitation falling
as rain, causing accelerated loss of the snowpack, a further increase
in runoff and an even greater likelihood of flooding. At the same time,
warmer temperatures will lead to a rise in the snowline and, on
average, a reduction in the springtime snowpack that is so vital for
sustaining stream and river flows into the summer. For the rest of the
U.S., projections indicate a continuation of the shift of precipitation
toward more precipitation falling in the more intense (i.e.,
convective) rainfall events. Reducing the time for rainfall to seep
into aquifers has the effect of increasing runoff, especially once the
upper layer of soil has become saturated, thereby increasing the
likelihood of high river levels and flooding. Warmer summertime
temperatures, and a greater interval between significant rainfall
events, are projected by many of the models to lead to increased
evaporation of soil moisture in the Great Plains, and so a more rapid
onset of drought conditions. For the Great Lakes, most models project a
few foot lowering of lake levels as the increase in summertime
evaporation exceeds the increase in winter precipitation, significantly
impacting community, recreational and commercial use of lake
waters.\38\ Reduced duration and extent of snowfall will also affect
the Northeast and other areas, likely shortening the ski season and
lengthening the time for warm weather recreational use of the
landscape, assuming drying and fire do not become threats.
In the Arctic, the melting back of snow cover, river ice, and
permafrost, combined with offshore melting back of sea ice, will have
significant effects on wildlife and on movement generally across the
region. For many types of wildlife, the snow cover provides protection
and even habitat, and climate change is likely to break vital links
(e.g., lemmings and voles survive the winter mostly between the snow
layer and the underlying tundra, and their loss would deplete food
resources for snowy owls and foxes, etc.). Reindeer and caribou depend
on the snow cover to protect vegetation that serves as winter feed, and
episodic freeze-thaw conditions can create ice crusts that cannot be
easily broken, reducing access to the food necessary to survive. The
migrating herds also depend on frozen river ice in springtime to cross
rivers along migration routes to summer breeding grounds.\39\ Warmer
conditions are already leading to new species appearing in the Arctic,
and these new species will tend to push existing species northward,
likely eventually to extinction as the land ends and the Arctic Ocean
In addition, the melting of permafrost (and frozen sediments on the
continental shelves) has the potential to release large amounts of
methane (CH4) that is tied up in hydrates. On a per molecule
basis, methane is roughly 20 times as effective as trapping infrared
radiation as is a CO2 molecule, which is why there is so
much attention being devoted to human-induced changes in methane
concentrations (human contributions have caused about a 150 percent
increase in the preindustrial CH4 concentration). While
permafrost melting has begun, determining how much CH4 is
being released has proven quite difficult and so the IPCC projections
do not yet account for the potential warming influence of such
releases, but the potential for substantial releases is quite
significant, especially because warming in the Arctic is projected to
be greater than for the world as a whole.
Continued warming and changes in snowfall are also likely to
further increase the ongoing retreat of mountain glaciers and the great
ice sheets. In virtually all regions of the world, including on high
tropical mountains, glaciers are retreating at a rapid rate. Because
the annual glacier runoff in many cases serves as water resources for
wildlife and communities, the eventual loss of the glaciers is likely
to have very significant consequences in many regions around the world.
The area of the Greenland Ice Sheet that melts each year is also
increasing, and satellite observations indicate that ice mass is
decreasing.\40\ What appears to be happening is that rather than small
puddles forming and then refreezing in the fall, larger puddles are
forming, and then finding channels and crevasses to flow to the bedrock
and eventually into the ocean, allowing a greater fraction of the
increase in downward infrared radiation caused by the higher greenhouse
gas concentrations to go into melting of ice as opposed to the very
energy intensive process of evaporation of water. The situation is much
like what would happen if one of those decorative ice statues on
banquet tables were taken out of a freezer for longer and longer
intervals--if out for only a short period, the thin meltwater layer on
the statue might refreeze when the statue is put back in the freezer;
however, if kept out longer, the meltwater created each time would be
lost, and soon there would be no ice statue at all.\41\
Projections are that high-latitude warming of a few degrees Celsius
(so perhaps 5+F), which is projected for the second half of the 21st
century, would be likely to lead to the melting of roughly half of the
Greenland Ice Sheet over a period of up to several centuries,\42\
mirroring a similar event that occurred during the last
interglacial,\43\ likely mainly as the result of a particular set of
variations in the Earth's orbit at that time that brought comparable
warmth to high northern latitudes. The effects on sea level of such
extensive changes are discussed in the next section.
While much of the above discussion has focused on the projected
changes in seasonal to annual timescale changes, what really has most
effect on people and the environment are the extremes of the weather
that are combined to get the changes in the averages. The weather
(i.e., the instantaneous state of the atmosphere) is determined by the
interaction of all of the various forcings and gradients in the global
system. Observations indicate that day-to-day weather conditions tend
to vary about the mean conditions in a more-or-less standard way,
creating a bell-shaped distribution of conditions with a few instances
much above and below the average and a greater likelihood of the
conditions being near the average expected at each time of year. The
projected change in climate will shift this distribution, moving the
average higher, and thereby creating a much greater likelihood that
conditions will exceed a particular threshold (e.g., 90 or 95+F). The
likelihood of presently unusual events could also be changed if the
shape of the bell-like distribution is changed, which could occur, for
example, if the characteristics of the global circulation are changed
(e.g., by moving the winter jet stream relative to mountain ranges such
as the Himalayas, or by altering the oceans in ways that affect the
irregular cycling or intensity of El Nino or La Nina events).
As a result of the changes in climate, conditions such as heat
waves (which exacerbate the heat index and thermal stress in cities
\44\) and drought conditions favorable for wildfires are expected to
become more frequent and more intense. In fact, Dai et al. (2004)
calculate that the amount of land experiencing severe drought has more
than doubled in the last 30 years, with almost half of the increase
being due to rising temperatures rather than decreases in rainfall or
snowfall.\45\ Not surprisingly, therefore, observations indicate that
wildfires have been increasing on all continents, particularly sharply
in North America, and projections are that this trend is likely to
intensify with further increases in surface temperature.\46\ In
addition, freeze events, which are important to controlling many types
of pests and associated diseases, are projected to be less likely. As
already mentioned, the occurrence of more intense and more frequent
heavy rainfall events is likely to increase the occurrence of flooding.
Analyses by Milly et al. (2002) indicate that the frequency of very
large floods has increased substantially during the 20th century, which
is consistent with climate model simulations, and modeling studies
suggest that the trend will continue in the future.\47\ With respect to
the potential severity of this type of effect, results from the
Canadian climate modeling group cited in the U.S. National Assessment
indicate that the return period of what are now once in a hundred year
events will, by the end of the century, likely be reduced to about once
every 30 years, with even more severe events occurring once every
hundred years. In that much of society's infrastructure is only
designed to withstand once in a hundred year events, having more severe
events occurring more often than once a century is likely to increase
the likelihood of very damaging events,\48\ causing very adverse and
costly impacts for both society and the environment.
Some media reports and criticisms by skeptics question the rising
concern about the increasing risks from more intense and more frequent
occurrence of extreme weather events, indicating that no specific event
can be attributed to global warming. To better understand the
situation, consider the simple analogy of the Earth's weather being
equivalent to a pot of slowly boiling water, with each bubble
indicating an extreme event somewhere across the globe. If the heat
under the pot is turned up, there will be more bubbles, some of which
are the size of the previous largest bubble and perhaps some even
larger. There is no way to say that any particular bubble was due to
the increased heat or was bigger because of it, yet clearly the
intensified bubbling is due to the additional heat. Now, the real world
situation is further complicated by seasonal changes (roughly
equivalent to the heat being slowly turned up and down, but each time
to higher levels), spatial linkages resulting from the oceanic and
atmospheric circulations (roughly equivalent to adding noodles to the
boiling water), and the presence of mountains and other geographic
features (roughly equivalent to having a pot of varying shape and
thickness); as a result formally detecting the changes in extreme
events is indeed a challenge. But there is no question that adding heat
to the system will lead to greater extremes (were the subtropics not so
warm, the incidence of tropical cyclones would be much less).
Consequences at the Coastal Interface of the Terrestrial and Marine
At coastlines, the consequences of the changes in marine and
terrestrial components come together. Because the coastal region
provides habitat to so many species, from shrimp to shore birds, and
from plant species to humans, past and projected changes occurring in
this boundary environment have particular importance for the
environment and society.
Bays, inlets, estuaries, barrier islands, marshes, wetlands, and
more provide habitat to a wide range of species, in some cases year-
round and in other cases at particular times as species migrate from
one region to another. These regions are breeding grounds for fish and
fowl, and those, including humans, that live off of them. The
particular conditions each species needs results from the balance
between the saline ocean waters and the terrestrial freshwaters, all
mixed by the tides and ocean currents and moderated and mixed by the
particular weather conditions ranging from mild sea breezes to raging
storms. Nutrients are provided by the oceanic and river flows and by
atmospheric deposition, all then cycled through by the chain of living
plants and animals (including both terrestrial and marine life).
Productivity has been able to develop as a result of the relative
stability of the shoreline environment, with niches being filled to
make optimal use of available resources.
Climate change is not the only stress that is now being imposed on
this environment. Harvesting, air and water pollution, encroachment,
toxics, excessive nitrogen deposition, oxygen deprivation, and more are
all creating stresses, and now comes sea level rise and climate change
(i.e., warming, changes in precipitation that alter runoff, intensified
storms, changes in winds and ocean currents, and more). Sea level has
been roughly stable for the past several thousand years, yet has
recently begun to rise. Warming of ocean waters (which leads to their
expansion, just as mercury expands to fill a thermometer as the
temperature increases) and water added to the ocean, likely mostly from
melting of mountain glaciers, caused global sea level to rise 4-8
inches (10-20 cm) during the 20th century.\49\ For the 21st century,
the early projections have been that sea level will go up by another
12-20 inches (30-50 cm); \50\ with the apparent acceleration in the
melting of the Greenland Ice Sheet that has been observed,\51\ the
Arctic Climate Impact Assessment concluded that projections of sea
level rise for the 21st century could quite possibly exceed 20 inches
(50 cm), reaching toward the upper limit of the IPCC projections. What
is particularly problematic is that the factors contributing the most
to sea level rise, namely thermal expansion and the ultimate melting of
the Greenland and West Antarctic Ice Sheets, are likely to continue to
contribute to sea level rise for centuries after the rise in greenhouse
gases is halted, meaning that significant areas of the shoreline will
be inundated and lost over coming decades and centuries, and that
protection of the most valuable regions through levee construction
needs to receive early attention.\52\ To date, no nation has prepared
for sea level rise of a meter or more within a century, but the
possibility warrants appropriate planning beyond normal disaster
While the rise in sea level itself might seem small, when amplified
by the effects of storms creating waves and storm surges, the situation
is particularly threatening. In the Arctic, the melting away from the
shore of the sea ice away has allowed winter waves to pound the barrier
islands, causing significant erosion. This is particularly a problem
because coastal regions are where many native communities have been
located, often for thousands of years, in order to harvest the bounty
of both the land and the ocean. The most endangered community is
currently Shishmaref, which is being eroded away so rapidly that
community relocation has already started. As the Government
Accountability Office has projected,\53\ relocation of all the
endangered villages is going to be very costly. Both the climate
changes themselves and the relocations will lead to substantial
disruption of subsistence harvesting \54\ and indigenous culture and
traditions that have sustained these communities through thousands of
For coastal regions exposed to hurricanes and the waves and the
storm surges that they create, the danger is also very great. While
international assessments have generally suggested that developing
countries are more vulnerable to global warming than developed nations
because they lack the resources to be able to adapt, the developed
nations have at risk far greater investments in coastal infrastructure,
including roads, highways, railroads, airports, ports, sewage treatment
facilities, and residential and commercial buildings. Many of these
structures are fully exposed to the oceans, unlike New Orleans, which
at least at one time was protected by extensive wetlands. With the
power and duration of intense hurricanes observed to be increasing, and
with greater changes likely ahead as ocean temperatures continue to
rise, the coastal region is particularly at risk. While building levees
is likely to be able to work for a while, if sea level rise reaches a
few meters within a few centuries, retreat is ultimately going to be
required in many regions. Disrupted coastlines are also likely to
disrupt the resident and migrating wildlife. While some new wetlands
may be formed further inland, it is unlikely that such new areas will
be as extensive or as able to fill the many roles of existing areas,
especially as the process of coastal inundation will be continuous
rather than allowing full development at some altered, but fixed,
change in sea level.
Summary and Concluding Thoughts
While the discussion above has focused on the great variety of
changes and interactions that the increase in the CO2
concentration and changes in climate are leading to (and the above list
is only a sampling), what will be experienced by the environment and
society will be all of these changes together, plus the impacts of all
of the other changes going on, ranging from air and water pollution to
resource utilization and land cover change. While a number of these can
be (and are being) ameliorated by regulations and policy, climate
change presents several unique aspects. First, climate change will keep
growing and growing--it is an influence that can only be slowed, not
reversed (at least in any reasonable time horizon). Second, it is fully
global, and because the world is environmentally and economically
interconnected, impacts in one location can create impacts in other
locations. And third, the changes are larger and occurring more rapidly
than can be accounted for using any analogs to the past, making very
real the potential for surprises, unexpected changes, unidentified
thresholds, and tipping points. As Australian author and scientist
Barrie Pittock has put it, ``Uncertainty is inevitable, but risk is
For the natural world, change is already evident. Analyses by
Parmesan and Yohe (2003) indicate with very high confidence that a
large fraction of the plant and animal species studied are showing a
response consistent with that expected to result from changes in
climate.\56\ The types of responses include shifts in range (e.g., the
Inuits are spotting types of birds never seen before that far north),
changes in number and vitality (e.g., the polar bear population around
Hudson's Bay), and unprecedented susceptibilities (e.g., to pest
outbreaks). There is no question that the natural world is changing,
and the main question is how much change can occur before changes in
keystone species begin to cause the collapse of ecosystems (e.g., of
the Amazon rainforest \57\) and significant reductions in the ecosystem
services (e.g., air and water purification, food and fiber generation,
fish and shrimp production) that these systems provide to society. Of
particular concern are how all of these changes affect migrating
species from birds to butterflies and fish to whales, for they have
generally developed a dependence on a timeline of resources at
particular locations in order to survive, and significant loss could
occur from substantial disruption of any of them.
While modern society may seem less dependent on the natural world,
many linkages remain, not only between communities and nearby
ecosystems, but also with conditions around the world. Increased
temperatures (along with higher absolute humidity--so much higher heat
indices) will stress those not able to stay in and pay for air-
conditioned space. While those in colder climates that have tight
houses can readily transfer savings on heating bills to pay for
increased cooling, those in more open homes in presently southern
climates will have to invest in considerable structural upgrading to
make air-conditioning a viable remedy. That the cost of upgrading will
be high, and the need for it greatest among the poor, will create a
serious issue of equity, with the least fortunate responsible for the
lowest energy use yet suffering the largest consequences.
The effects will not only be personal. Not only do modern societies
draw resources and food from ecosystems and countries around the world,
but products also come from around the world and investment portfolios
typically include a mix of international stocks, coupling one's
economic state to the state of the world. In addition, with people
traveling extensively for business and pleasure, the health of people
around the world is interconnected, and what happens in one location
can soon affect those in other locations. In that warm conditions are
generally more favorable for the presence of disease vectors such as
mosquitoes, warming will lead to the loss of the ally of freezing
conditions for helping to control mosquito populations. As a result,
except in regions (such as the U.S.) where rigorous public health
practices and community building standards have over time separated the
disease from the disease vector and from people, warming and increased
precipitation are likely to exacerbate the likelihood of exposure to
disease vectors.\58\ Even in countries such as the U.S., isolated
occurrences are likely given the magnitude of international travel, and
so extra resources will have to be devoted to maintaining high
standards and quickly addressing new infestations (e.g., by spraying
for mosquitoes). Changes in the distribution and level of activity of
various plant species can also exacerbate health problems, as for
example the increased production of pollen that can exacerbate
incidence of asthma.\59\
The shifting climatic patterns and rising sea level are likely to
be most problematic for small countries and other similarly sized
entities. For island nations made up mainly of coral atolls, rising sea
level and higher storm surges are already having deleterious effects on
aquifers, and continuing sea level rise is likely to inundate several
island nations over the coming century. For small countries, especially
those that have focused on growing a particular crop, shifting climatic
patterns are likely to require changes in crop species, which is likely
to be difficult to compete as there will likely be the need to break
into new markets. Whereas many indigenous peoples, including the
American Indian, have long traditions of adaptation, at the root of
previous successes was often the ability to relocate; with tribal
reservations now fixed, community relocation is no longer possible, and
medicinal plants and other historic species are likely to shift to
quite removed locations, negating the passed on ecological wisdom
developed over so many generations.
For many regions, changes in water resources will be the most
important effect, with increased competition for reduced resources
among agricultural, community, industrial and ecological interests. For
coastal regions, sea level rise and increases in storm intensity will
pose the most important threats, requiring both enhancement of
resilience in the near-term and possible relocation in the long-term.
For those in urban areas, the increased likelihood of heat stress
conditions and higher air pollution levels \60\ may well pose the most
significant threat. Because the particular situation of each region
will depend on its individual circumstances, as indicated in Table 1,
it is vital that the Nation have an ongoing assessment activity that
helps regions and sectors to understand, prepare for, and ameliorate
the most deleterious circumstances. Such an effort, as is called for in
the Global Change Research Act of 1990 [Pub.L. 101-606], was begun in
earnest in 1997 with the undertaking of the U.S. National Assessment;
that this effort was essentially terminated in 2001 after having made
significant progress in involving stakeholders in regional activities
has been most unfortunate.
What is most clear is that global climate change is underway and
that the risk of adverse consequences for both marine and terrestrial
environments is quite high. While it will take substantial efforts and
many decades to limit emissions of greenhouse gases and bring climate
change to a stop as called for in the U.N. Framework Convention on
Climate Change ratified by the U.S. Senate in 1992, that virtually no
effort is being made by the U.S. to accomplish this in the face of all
the scientific information about impacts is most unfortunate. For the
people of the Arctic and of the U.S. whom I have had the privilege of
representing in assessment activities, I urge your most urgent
consideration of a national effort to prepare for the inevitable
climate change that lies ahead and to take actions to sharply limit the
climate change that will be brought on by future emissions.
Websites of Particular Relevance to Understanding of Climate Impacts
U.S. National Assessment of the Potential Consequences of Climate
Variability and Change (http://www.usgcrp.gov/usgcrp/nacc/default.htm)
Arctic Climate Impact Assessment (http://www.acia.uaf.edu/)
Intergovernmental Panel on Climate Change: (http://www.ipcc.ch/)
Millennium Ecosystem Assessment: (http://
Climate Institute (http://www.climate.org/CI/index.shtml)
Table 1: Examples of important climate change consequences affecting
regions of the U.S.*
Examples of Key Consequences Affecting:
Regions and -----------------------------------------------------
Subregions the Environment the Economy People's Lives
Northeast--New Northward shifts Reduced Rising
England and in the ranges of opportunities summertime
upstate NY, plant and animal for winter heat index
Metropolitan NY, species (e.g., of recreation will make
Mid-Atlantic colorful maples); such as cities less
Coastal wetlands skiing; comfortable
inundated by sea- increased and require
level rise. opportunities more use of
for warm- air-
recreation Reduced snow
such as hiking cover.
will need to
Southeast--Central Increased loss of Increased Increased
and Southern barrier islands productivity flooding along
Appalachians, and wetlands, of hardwood coastlines,
Gulf Coast, affecting coastal forests, with with increased
Southeast ecosystems; northward threat from
Changing forest shift of storms; Longer
character, with timber period of high
possibly greater harvesting; heat index,
fire and pest Increased forcing more
threat. intensity of indoor living.
Midwest--Eastern Higher lake and Increasing Lowered lake
Midwest, Great river agricultural and river
Lakes temperatures productivity levels,
cause trend in in many impacting
fish populations regions, recreation
away from trout ensuring opportunities;
toward bass and overall food Higher
catfish. supplies but summertime
possibly heat index
lowering reduces urban
commodity quality of
Great Plains-- Rising wintertime Increasing Altered and
Northern, temperatures agricultural intensified
Central, allow increasing productivity patterns of
Southern, presence of in north, more climatic
Southwest/Rio invasive plant stressed in extremes,
Grande Basin species, the south; especially in
affecting Summertime summer;
wetlands and water Intensified
other natural shortages springtime
areas; Disruption become more flood and
of migration frequent. summertime
routes and drought
West--California, Changes in natural Rising Shifts toward
Rocky Mountains/ ecosystems as a wintertime more warm
Great Basin, result of higher snowline leads season
Southwest/ temperatures and to earlier recreation
Colorado River possibly runoff, activities
Basin intensified stressing some (e.g., hiking
winter rains. reservoir instead of
Increased crop Greater fire
yields, but potential
with need for created by
greater more winter
controls of rains and dry
weeds and summers;
Pacific Northwest Added stress to Earlier winter Reduced
salmon runoff will wintertime
populations due limit water snow pack will
to warmer waters availability reduce
and changing during warm opportunities
runoff patterns. season; Rising for skiing,
Alaska Forest disruption Damage to Retreating sea
due to warming infrastructure ice and
and increased due to earlier
pest outbreaks; permafrost snowmelt alter
Reduced sea ice melting; traditional
and general Disruption of life patterns;
warming disrupts plant and Opportunities
polar bears, animal for warm
marine mammals, resources season
and other supporting activities
wildlife. subsistence increase.
Coastal and Increased stress Increased Intensification
Islands--Pacific on natural pressure on of flood and
Islands, South biodiversity as water landslide-
Atlantic Coast pressures from resources inducing
and Caribbean invasive species needed for precipitation
increase; industry, during
Deterioration of tourism and tropical
coral reefs. communities storms; More
due to extreme year-
storms, and in the
Native People and Shifts in The shifting Disruption of
Homelands ecosystems will climate will the religious
disrupt access to affect and cultural
medicinal plants tourism, water interconnectio
and cultural rights, and ns of Native
resources. income from people and the
use of natural environment.
* MacCracken, M. C., 2001: Climate Change and the U.S. National
Assessment, pp. 40-43 in McGraw Hill Yearbook of Science and
Technology 2002, McGraw-Hill, New York, 457 pp.
Attachment 1: Arctic Temperature Change--Over the Past 100 years
Released June 28, 2005 by Gordon McBean, Lead author of Chapter
2, ACIA Report. The authors of Chapter 2 are: G. A. McBean, G.
Alekseev, D. Chen, E. Forland, J. Fyfe, P.Y. Groisman, R. King,
H. Melling, R. Vose and P. H. Whitfield.
This note has been prepared in response to questions and comments
that have arisen since the publication of the Arctic Climate Impact
Assessment overview document--``Impacts of a Warming Arctic.'' It is
intended to provide clarity regarding some aspects relative to the
material from Chapter 2 Arctic Climate--Past and Present that will
appear in full with the publication of the ACIA scientific report in
The authors of Chapter 2 began their work in 2000. It was
recognized that the observational data base for the Arctic is limited,
with few long-term stations and a paucity of observations in general.
Because at that time the published literature on Arctic temperature
changes was not comprehensive nor up-to-date, it was decided to
undertake a new set of calculations, based only on data sets that were
fully documented in the literature, but updated to the present, using
the documented procedures. The Global Historical Climatology Network
(GHCN) data base (updated from Peterson and Vose, 1997) was selected
for this analysis. A comparison was made with the Climatic Research
Unit (CRU) data base (Jones and Moberg, 2003) because both data bases
were used in the Third Assessment Report (IPCC, 2001b) to summarize the
patterns of temperature change over global land areas since the late
19th century. The GHCN dataset includes selected quality controlled
long-term stations suitable for climate change studies. The U.S.
National Climate Data Center was asked to do the calculations since
they had both datasets in their archives.
There are several possible definitions of the Arctic depending on,
for example, tree line, permanent permafrost, and other factors. It was
decided for purposes of this analysis that the latitude 60+N would be
defined as the southern boundary. Although somewhat arbitrary, this is
no more arbitrary than choosing 62+N, 67+N or any other latitude. Since
the marine data in the Arctic are very limited in geographical and
temporal coverage, it was decided, for consistency, to only use data
from land stations.
The analysis showed that the annual land-surface air temperature
variations in the Arctic (north of 60+N) from 1900 to 2002 using the
GHCN and the CRU datasets led to virtually identical time series, and
both documented a statistically significant warming trend of 0.09 +C/
decade during that period (Figure 1). Annual land-surface air
temperature trends were calculated for the periods 1900-2003, 1900-
1945, 1946-1965, and 1966-2003. Trends were calculated from annually
averaged gridded anomalies using the method of Peterson et al. (1999)
with the requirement that annual anomalies include a minimum of 10 22
months of data. For the period 1900-2003, trends were calculated only
for those 5+ x 5+ grid boxes containing annual anomalies in at least 70
of the 104 years. The minimum number of years required for the shorter
time periods (1900-1945, 1946-1965, and 1966-2003) was 31, 14, and 26,
Figure 1. Annual anomalies of landsurface air temperature (+C)
from 60-90+N for the period 1900-2002. Anomalies are relative
to a 1961-90 base period. The smoothed curve was created using
a 21-point binomial filter giving near decadal averages. Panel
(a)(upper) depicts the GHCN time series (updated from Peterson
and Vose, 1997), and panel (b)(lower) depicts the CRU time
series (Jones and Moberg, 2003).
In response to critical comments about the ACIA analysis of the
temperature record, it is important to note that the choice to use the
CHCN dataset was made before the analysis was done, before the Polyakov
et al. (2002) paper was published and based on the logical arguments
that it was the most comprehensive land-station data base available and
was well documented in the literature. As noted, the other well-
documented data base, of the CRU, gave virtually identical results.
It needs to be stressed that the spatial coverage of the region
north of 60+ N is quite varied. During the period (1900-1945), there
are 7 grid boxes meeting the requirement of 31 years of data in the
Alaska/Canadian Arctic/West Greenland sector. The largest number of
grid boxes is in the North Atlantic sector (East Greenland/Iceland/
Scandinavia) with 13 grid boxes. There were 10 grid boxes over Russia.
The coverage for periods since 1945 is more uniform. Based on these
analyses, the annual land-surface air 23 temperature (+C) from 60-90+N,
smoothed with a 21-point binomial filter giving near decadal averages,
were warmer in the most recent decade (1990s) than they were in the
The analysis of Polyakov et al. (2002) showed the 1930-1940s period
warmer than the most recent decade. They used individual stations and
the distributions of stations, according to the Figure 1 in their
paper, was quite varied for different time periods. The total number of
stations of more than 65 years is 8 stations in the Alaska/Canada/West
Greenland sector compared to 43 stations in the North Atlantic/Russian
sector. Over the whole period of record, their analysis considered 18
stations for the Alaska/Canada/West Greenland sector compared with 50
stations from the North Atlantic/Russian sector. The Polyakov paper
also considered only maritime (or coastal) stations north of 62+N,
while the analysis presented in Chapter 2 of the ACIA report considered
all land stations north of 60+N. It should be noted that several of the
locations of greatest warming in recent decades are apparent as a
result of the continental stations between 60+ and 62+N (in Russia,
Canada and Alaska).
Another important paper is that of Johannessen et al. (2004) who
found, with a dataset extensively augmented by Russian station data not
previously available, that the ``early warming trend in the Arctic was
nearly as large as the warming trend for the last 20 years'' but
``spatial comparison of these periods reveals key differences in their
patterns''. Their analysis, consistent with the analysis presented in
the ACIA Chapter 2, showed that average annual temperatures were higher
in the most recent decade than in the 1930-1940 period. Further, the
pattern of temperature increases over the past few decades, they note,
is different and more extensive than the pattern of temperature
increases during the 1930s and 1940s, when there was weak (compared to
the present) lower-latitude warming.
Chapter 3 of the ACIA report, entitled ``The Changing Arctic:
Indigenous Perspectives'' documents the traditional knowledge of Arctic
residents and indicates that substantial changes have already occurred
in the Arctic and supports the evidence that the most recent decade is
different from those of earlier in the 20th century.
Although all data bases suffer from a lack of data in the Alaska/
Canada/West Greenland sector except for the last 50 years, Polyakov et
al. (2002), ACIA Chapter 2, Johannessen et al. (2004), Serreze, et al.
(2000) and other analyses all show that the recent decades are warm
relative to at least most of the period of instrumental record.
The rate of warming in the recent decades is also much greater than
the average over the past 100 years (Figure 2). Least-squares linear
trends in annual anomalies of arctic (60+ to 90+ N) land-surface air
temperature from the GHCN (updated from Peterson and Vose, 1997) and
CRU (Jones and Moberg, 2003) datasets for the period 1966-2002 both
gave warming rates of 0.38 (+C/decade). This is consistent with the
analysis of Polyakov et al. (2002) and confirmed with satellite
observations over the whole Arctic, for the past 2 decades (Comiso,
Figure 2. Trends in land-surface air temperatures (solid lines)
and their 95 percent significance levels (dashed lines) over
the past 120 years for (a) 60+ to 90+ N and (b) 0 to 60+ N
(data from the GHCN dataset, updated from Peterson and Vose,
The modeling studies Johannessen et al. (2004) showed the
importance of anthropogenic forcing over the past half century for
modeling the arctic climate. ``It is suggested strongly that whereas
the earlier warming was natural internal climate-system variability,
the recent SAT (surface air temperature) changes are a response to
anthropogenic forcing''. A new paper, published after completion of the
ACIA Chapter, by Bengtsson et al. (2004) states in its summary, with
reference to the warming of the 1930-1940s: ``This study suggests that
natural variability is a likely cause . . .''
As stated by the IPCC (2001b), model experiments show ``a maximum
warming in the high latitudes of the Northern Hemisphere''. In
reference to warming at the global scale, the IPCC (2001a) also
concluded, ``There is new and stronger evidence that most of the
warming observed over the past 50 years is attributable to human
activities''. Karoly et al. (2003) concluded that temperature
variations in North America during the second half of the 20th century
were probably not due to natural variability alone. Zwiers and Zhang
(2003) were able to detect the combined effect of changes in greenhouse
gases and sulfate aerosols over both Eurasia and North America for this
period, as did Stott et al. (2003) for 25 northern Asia (50-70+ N) and
northern North America (50-85+ N). In any regional attribution study
for the Arctic (which has not yet been published), the importance of
variability must be recognized. In climate model simulations, the
arctic signal resulting from human-induced warming is large but the
variability (noise) is also large. Hence, the signal to noise ratio may
be lower in the Arctic than at lower latitudes. In the Arctic, data
scarcity is another important issue. However, it is implausible to
conclude that the warming of the recent decades is not of anthropogenic
In the context of this report, the authors agreed on the following
terminology. A conclusion termed as ``very probable'' is to be
interpreted that the authors were 90-99 percent confident in the
conclusion. The term ``probable'' conveys a 66-90 percent confidence.
The conclusions of Chapter 2 were that:
``Based on the analysis of the climate of the 20th century, it
is very probable that the Arctic has warmed over the past
century, although the warming has not been uniform. Land
stations north of 60+ N indicate that the average surface
temperature increased by approximately 0.09 +C/decade during
the past century, which is greater than the 0.06 +C/decade
increase averaged over the Northern Hemisphere. It is not
possible to be certain of the variation in mean land-station
temperature over the first half of the 20th century because of
a scarcity of observations across the Arctic before about 1950.
However, it is probable that the past decade was warmer than
any other in the period of the instrumental record.''
Polar amplification refers to the relative rates of warming in the
Arctic versus other latitude bands. Using comparable data sets (the
GHCN dataset), the warming for land stations over the region north of
60+N, is almost double that for stations in the latitude bands 0-60+N
(Figure 2). The conclusions of Chapter 2 were that:
``Evidence of polar amplification depends on the timescale of
examination. Over the past 100 years, it is possible that there
has been polar amplification, however, over the past 50 years
it is probable that polar amplification has occurred.''
Bengtsson, L., V.A. Semenov and O.L. Johannssen, 2004; The early
twentieth-century warming in the Arctic--a possible
mechanism. J. Climate, 17, 4045-4057.
Comiso, J., 2003. Warming trends in the Arctic from clear sky satellite
observations. Journal of Climate, 16:3498-3510.
IPCC, 2001a. Climate Change 2001: Synthesis Report. A Contribution of
Working Groups I, II, and III to the Third Assessment
Report of the Intergovernmental Panel on Climate Change.
Watson, R.T., and the Core Writing Team (eds.). Cambridge
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\1\ Prepared in cooperation with Dr. Michael MacCracken, chief
scientist for climate change programs at the Climate Institute,
Washington DC, and Dr. Rosina Bierbaum, Dean of the School of Natural
Resources and Environment at the University of Michigan in Ann Arbor.
\2\ National Assessment Synthesis Team, 2000: Climate Change
Impacts on the United States: The Potential Consequences of Climate
Variability and Change: Overview Report, U. S. Global Change Research
Program, Cambridge University Press, Cambridge UK, 154 pp.
[Also see Foundation Report, U.S. Global Change Research Program,
Cambridge University Press, Cambridge UK, 612 pp. published in 2001].
The most significant results of the National Assessment were summarized
in the U.S. Climate Action Report--2002, which was submitted to the
U.N. under the Framework Convention on Climate Change as the Third
National Communication of the United States of America (thus
representing the official position of the U.S. Government in a document
formally approved by all of the involved agencies and departments);
this document is available from the U.S. Government Printing Office
website at http://bookstore.gpo.gov and is posted at http://
\3\ Arctic Climate Impact Assessment (ACIA), 2004: Impacts of a
Warming Arctic: Arctic Climate Impact Assessment, Cambridge University
Press, 140 pp. [Also see ACIA, 2005, Cambridge University Press, 1042
\4\ The Arctic Council was established on September 19th, 1996 in
Ottawa, Canada. The Arctic Council is a high-level intergovernmental
forum that provides a mechanism to address the common concerns and
challenges faced by the Arctic governments and the people of the Arctic
as a means of improving the economic, social and cultural well being of
the north. The national members of the Council are Canada, Denmark,
Finland, Iceland, Norway, the Russian Federation, Sweden, and the
United States of America; the Association of Indigenous Minorities of
the North, Siberia and the Far East of the Russian Federation, the
Inuit Circumpolar Conference, the Saami Council, the Aleutian
International Association, Arctic Athabaskan Council and Gwich'in
Council International are Permanent Participants in the Council. Many
additional entities participate through a provision that provides for
non-arctic states, inter-governmental and inter-parliamentary
organizations and nongovernmental organizations to become involved as
\5\ The International Arctic Sciences Committee (IASC) was founded
28 August 1990 by national science organizations representing all of
the arctic countries. It provides the major venue for national science
organizations, mostly academies of science, to facilitate and foster
cooperation in all fields of arctic research. IASC currently has
participation by scientists from Canada, China, Denmark, Finland,
France, Germany, Iceland, Italy, Japan, The Netherlands, Norway,
Poland, Republic of Korea, Russia, Sweden, Switzerland, United Kingdom,
and the United States.
\6\ The IPCC's assessments are all published by Cambridge
University Press, and are also available over the Internet at http://
www.ipcc.ch. IPCC's Fourth Impact Assessment Report is due to be
completed in 2007.
\7\ IPCC, 2001: Climate Change 2001: The Scientific Basis, edited
by J. T. Houghton et al., Cambridge University Press, 881 pp., see also
\8\ For example, see http://data.giss.nasa.gov/gistemp/2005/.
Results of other centers give similar results.
\9\ Such reconstructions estimate past values of surface
temperature using tree-rings, coral growth patterns, changes in
vegetation indicated by changes in pollen preserved in lake sediments,
\10\ For example, see Mann, M. E., and P. D. Jones, 2003: Global
surface temperatures over the past two millennia. Geophysical Research
Letters 30, 1820-1824, doi. 10.1029/2003 GL017814. Controversies over
the findings reported in this initial paper have largely been addressed
over the years since it was published.
\11\ See Attachment 1 for an overview by the authors of ACIA's
chapter on past climate change regarding the unprecedented patterns of
modern warming and reconciling this finding with the analyses of
supposed similarly warm conditions in the early to mid-20th century.
\12\ The near final draft of a tightly focused assessment by the
U.S. Climate Change Science Program (see http://www.climatescience.gov/
Library/sap/sap1-1/third-draft/default.htm) of trends in surface and
upper troposphere temperatures indicates that previous criticisms that
warming rates have been significantly different are not valid. This
focused assessment reports near resolution of this issue as a result of
studies that have identified corrections needed in satellite and
balloon records as a result of instrument and observational factors.
\13\ These estimates allow for uncertainties in projections of
future energy-related emissions. However, two other factors can also
introduce uncertainties. First, present models have only a limited
treatment of the processes that govern how rapidly CO2 will
be taken up by the land and ocean carbon reservoirs; preliminary
studies by Cox et al. (Cox, P.M., R.A. Betts, C.D. Jones, S.A. Spall,
and I.J. Totterdell, 2000: Acceleration of global warming due to carbon
cycle feedbacks in a coupled climate model, Nature, 408, 184-187) and
Fung et al. (Fung, I., S.C. Doney, K. Lindsay, and J. John, 2005:
Evolution of carbon sinks in a changing climate, Proceedings of the
National Academy of Sciences (USA), 102, 11201-11206, doi:10.1073/
pnas.0504949102) indicate that current models are overestimating the
amount of carbon that can be taken up, thus leading to small
underestimates of the rate of warming. Second, limits in our estimates
of how the climate will respond to changing atmospheric composition are
estimated to have the potential to increase or decrease the temperature
changes in 2050 by about 0.3+C (roughly 0.5+F) and in 2100 by about
twice this amount, with the likelihood (as a result of recent studies
of the likely effects of sulfate aerosols) that the change could be
greater than estimated more likely than that these are overestimates.
\14\ ppmv stands for parts per million by volume, or number of
CO2 molecules per million molecules of air.
\15\ See Doney, S.C., 2006: The dangers of ocean acidification,
Scientific American, 294(3), March 2006, 58-65; and Ocean Acidification
Due to Increasing Atmospheric Carbon Dioxide, Royal Society, 2005.
Available at http://www.royalsoc.ac.uk/displaypagedoc.asp?id=13314.
\16\ See Kleypas, J. A., R. W. Buddemeier, D. Archer, J-P. Gattuso,
C. Langdon, and B. N. Opdyke, 1999: Geochemical consequences of
increased atmospheric carbon dioxide on coral reefs, Science, 284, 118-
120; and Buddemeier, R. W., J. A. Kleypas, and R. B. Aronson, 2004:
Coral reefs & global climate change: Potential contributions of climate
change to stresses on coral reef ecosystems, Prepared for the Pew
Center on Global Climate Change, http://www.pewclimate.org/global-
\17\ See: Orr, J.C., V.J. Fabry, O. Aumont, L. Bopp, S.C. Doney,
R.A. Feely, A. Gnanadesikan, N. Gruber, A. Ishida, F. Joos, R.M. Key,
K. Lindsay, E. Maier-Reimer, R. Matear, P. Monfray, A. Mouchet, R.G.
Najjar, G.-K. Plattner, K.B. Rodgers, C.L. Sabine, J.L. Sarmiento, R.
Schlitzer, R.D. Slater, I.J. Totterdell, M.-F. Weirig, Y. Yamanaka, and
A. Yool, 2005: Anthropogenic ocean acidification over the twenty-first
century and its impact on marine calcifying organisms, Nature, 437,
\18\ Levitus, S., J. I. Antonov, and T. P. Boyer, 2005: Warming of
the world ocean, 1955-2003, Geophysical Research Letters, 32 (L02604),
doi: 10.1029/2004GL021592. Levitus et al. find that over 90 percent of
the energy trapped by the increasing concentrations of greenhouse gases
ends up in the ocean.
\19\ Barnett, T. P., D. W. Pierce, K. M. AchutaRao, P. J. Gleckler,
B. D. Santer, J. M. Gregory, and W. M. Washington, 2005: Penetration of
human-induced warming into the world's oceans, Science, 309, 284-287.
\20\ For example, see Webster, P. J., G. J. Holland, J. A. Curry,
and H.-R. Change, 2005: Changes in tropical cyclone number, duration,
and intensity in a warming environment, Science, 309, 1844-1846 and
Emanuel, K. A., 2005: Increasing destructiveness of hurricane intensity
on climate, Nature, 326, 483-485.
\21\ Anthes, R. A., R. W. Corell, G. Holland, J. W. Hurrell, M. C.
MacCracken, and K. E. Trenberth, 2006: Hurricanes and Global Warming--
Potential Linkages and Consequences, Bulletin of the American
Meteorological Society, 87 (May, in press). With regard to the most
important limitation in detection studies, it has been the presumption
by a number of investigators (e.g., Pielke et al., 2005, Bulletin of
the American Meteorological Society, 86, 1571-1575) that the response
should be a linear trend in hurricane number (or in other factors) over
the course of the century that is made dubious by many detection-
attribution studies that indicate that human influences led to a time
history of Northern Hemisphere temperature change during the 20th
century consisting of warming early in the century, a slight cooling in
mid-century (especially in the North Atlantic sector that is key in
affecting hurricane characteristics), and then a sharp warming since
\22\ Building societal resilience through adaptive efforts could
include, in the short-term, more effective evacuation, stronger levees,
beach restoration, enhancing vegetation cover of dunes, strengthening
of buildings, etc., and longer-term, withdrawal from the most
vulnerable areas, enhanced building codes, storm surge barriers (e.g.,
being proposed to protect New York harbor), adding capacity to
evacuation routes, etc.
\23\ See for example: Sarmiento, J., R. Slater, R .Barber, L. Bopp,
S.C. Doney, A.C. Hirst, J. Kleypas, R. Matear, U. Mikolajewicz, P.
Monfray, V. Soldatov, S. Spall, R. Slater, and R. Stouffer, 2004:
Response of ocean ecosystems to climate warming, Global Biogeochemical
Cycles, 18, GB3003, doi:10.1029/2003GB002134.
\24\ For example, see report in the Washington Post, April 15, 2006
entitled ``Warming Arctic is Taking a Toll,'' which reports on results
of a scientific study appearing in the journal Aquatic Mammals that
walrus calves are being found abandoned at sea (and almost certain to
starve and drown) because there is no longer any sea ice for them to
rest on in the areas shallow enough for their mothers to feed off the
\25\ Policy Document is available at: www.acia.uaf.edu/PDFs/
\26\ Karnosky, D. F., K. S. Pregitzer, D. R. Zak, M. E. Kubiske, G.
R. Hendrey, D. Weinstein, M. Nosal, and K. E. Percy, 2005: Scaling
ozone responses of forest trees to the ecosystem level in a changing
climate, Plant, Cell, and Environment, 28, 965-981.
\27\ Reich, P. B., S. E. Hobbie, T. Lee, D. S. Ellsworth, J. B.
West, D. Tilman, J. M. H. Knops, S. Naeem, and J. Trost, 2006: Nitrogen
limitation constrains sustainability of ecosystem response to
CO2, Nature, 440, 922-925.
\28\ Indeed, a number of studies suggest that, along with
technology and seed enhancements, the increased CO2
concentration is already contributing to higher yields.
\29\ Note, however, that greater year-to-year variability or more
frequently exceeding various temperature and/or moisture (or dryness)
thresholds may make optimization to a narrow range of climatic
variables more risky, and farmers may instead choose not to select seed
strains that tolerate a wider range of conditions in exchange for
slightly reduced productivity. A key determinant will be how rapidly
improvements are made in the skill of seasonal forecasts, a topic on
which research attention is being closely focused.
\30\ National Assessment Synthesis Team, 2001: Climate Change
Impacts on the United States: The Potential Consequences of Climate
Variability and Change: Foundation, U.S. Global Change Research
Program, Cambridge University Press, 612 pp. Available at http://
\32\ Breshears, D. D., et al. 2005: Regional vegetation die-off in
response to global-change-type drought, Proceedings of the National
Academy of Sciences, 102 (Oct. 18), 15144-15148. Available at http://
\33\ Emanuel, K., 2005: Increasing destructiveness of tropical
cyclones over the past 30 years, Nature 436, 686-688.
\34\ Friedlingstein, P., P. Cox, R. Betts, W. von Bloh, V. Brovkin,
S. Doney, M. Eby, I. Fung, B. Govindasamy, J. John, C. Jones, F. Joos,
M. Kawamiya, W. Knorr, K. Lindsay, H.D. Matthews, T. Raddatz, P.
Rayner, C. Reick, E. Roeckner, K.-G. Schnitzler, R. Schnur, K.
Strassmann, S. Thompson, A.J. Weaver, and N. Zeng, 2006: Climate-carbon
cycle feedback analysis; Results from the C4MIP model intercomparison,
Journal of Climate, in press.
\35\ See, for example, the Cox et al. and Fung et al. references
\36\ For comparison, the CO2 increase from preindustrial
to the present has been about 100 ppmv.
\37\ Beedlow, P.A., D.T. Tingey, D.L. Phillips, W.E. Hotsett, and
D.M. Olszyk, 2004: Rising atmospheric CO2 and carbon
sequestration in forests, Ecological Environment, 2, 315-322.
\38\ Warmer lake temperatures also mean delayed formation of lake
ice in the winter, perversely allowing a longer period for lake effects
storms to dump snow on the surrounding regions.
\39\ Arctic peoples and the energy industry also depend on the
frozen ground to enable moving around the Arctic; warming has already
reduced by about half the number of days the ground is hard enough for
movement of some oil-drilling equipment.
\40\ See ``Changes in the Velocity Structure of the Greenland Ice
Sheet'' by Eric Rignot and Pannir Kanagaratnam, Science Vol 311 17
February 2006, as well as ``The Greenland Ice Sheet and Global Sea-
Level Rise by Julian A. Dowdeswell, Science Vol 311 17 February 2006,
and also see Paterson, W.S.B., and N. Reeh, 2001: Thinning of the ice
sheet in northwest Greenland over the past forty years, Nature, 414,
\41\ Note that throughout this process, the temperature of the ice
surface when out on the banquet table would still be at the freezing
point, even with an infrared lamp shining on it. What matters is the
amount of heat being delivered while the temperature is fixed at the
melting point--not that the temperature has not risen (as some Skeptics
use as an argument to try to find fault with attributing the
unprecedented melting back of glaciers to the unprecedented human-
induced increase in greenhouse gas concentrations.
\42\ See Gregory, J.M., P. Huybrechts, and S.C.B. Raper, 2004:
Climatology: Threatened loss of the Greenland Ice Sheet, Nature, 428,
616; doi:10.1038/428616a. The IPCC's Third Assessment Report suggests
that the time scale for such melting would be millennia, but the recent
identification of the meltwater runoff mechanism for more rapid melting
is likely to lead to reductions in the estimates included in future
\43\ That such melting occurred is evident by the absence of older
ice in ice cores drilled in southern Greenland, but the presence of ice
that old in cores drilled in northern Greenland. Beach horizons on
remote islands that are located a few meters above present sea level
appear to confirm that a comparable amount of water (or perhaps even
more from some loss of the West Antarctic Ice Sheet) had been added to
the oceans. See ``Paleoclimatic Evidence for Future Ice-Sheet
Instability and Rapid Sea-Level Rise'' Jonathan T. Overpeck, Bette L.
Otto-Bliesner, Gifford H. Miller, Daniel R. Muhs, Richard B. Alley,
Jeffrey T. Kiehl Science 24 March 2006: Vol. 311. no. 5768, pp. 1747-
1750 DOI: 10.1126/science.1115159
\44\ The very hot European summer of 2003 that led to a month-long
heat wave that caused the premature deaths of tens of thousands is the
type of rare event that is estimated to have become much more likely as
a result of recent warming, and will become even more likely in the
future (e.g., see Schar, C. et al., 2004: The role of increasing
temperature variability in European summer heat waves, Nature, 427,
\45\ Dai, A., K. E. Trenberth, and T. Qian, 2004: A global dataset
of Palmer Drought Severity Index for 1870-2002: Relationship with soil
moisture and effects of surface warming, Journal of Hydrometeorology,
\46\ McKenzie, D., Z. Gedalof, D. L. Peterson, and P. Mote, 2004:
Climatic change, wildfire, and conservation, Conservation Biology, 18,
\47\ Milly, P.C.D., R.T. Wetherald, K.A. Dunne, and T.L. Delworth,
2002: Increasing risk of great floods in a changing climate, Nature,
\48\ A large hurricane striking New Orleans is only one example of
a very damaging event. Other examples identified during the U.S.
National Assessment included a storm surge into New York harbor, and
the entire northeast coastline that has been spared strong hurricanes
for several decades has since become increasingly developed, and
susceptible to very high damage events.
\49\ See IPCC Working Group I Third Assessment Report, 2001. Over
the past few decades, the rate of rise is consistent with a rate that
exceeds the upper end of this range, indicating that an acceleration in
the rate may have begun during this period (e.g., see Rignot, E., and
P. Kanagaratnam, 2005: Changes in the velocity structure of the
Greenland Ice Sheet, Science, 311, 986-990).
\50\ The full range for the IPCC estimate is about 4 to 35 inches
considering the full range of all emissions scenarios and climate
sensitivities, whereas the central estimate used in the text is for the
average response across all climate models and emissions scenarios.
\51\ Although projecting a rather significant buildup of ice on
East Antarctica, IPCC's Third Assessment Report projected only very
limited melting of the Greenland and West Antarctic Ice Sheets over the
21st century. Observations since publication of that report suggest
that at least the Greenland Ice Sheet is likely to experience
significant loss of ice as the warming builds up over coming decades.
\52\ Low levees have already been installed around LaGuardia
airport due to a severe storm some 50 years ago, and many additional
areas are at risk. Low lying islands in the Chesapeake Bay have also
been lost over recent times, more due to natural land subsidence than
human-induced sea level rise, but providing an insight into the likely
consequences of an acceleration of the rate of rise due to global
warming. And the severe loss of coastal wetlands in the Mississippi
delta region (again due mainly to other factors up to the present)
provides a telling example of how important the coastal islands are for
\53\ GAO, 2004: Alaska Native Villages: Villages Affected by
Flooding and Erosion Have Difficulty Qualifying for Federal Assistance,
Statement of Robert A. Robinson, Managing Director, Natural Resources
and Environment, GAO-04-895T.
\54\ It is substantially more difficult to catch a whale or seal by
chasing it in open waters than by waiting for it to surface at an air
\55\ Pittock, A. B., 2005: Climate Change: Turning Up the Heat,
Earthscan, London, 316 pp.
\56\ Parmesan, C., and G. Yohe, 2003: A globally coherent
fingerprint of climate change impacts across natural systems, Nature,
\57\ For example, see Cox, P.M., R.A. Betts, C.D. Jones, S.A.
Spall, and I.J. Totterdell, 2000: Acceleration of global warming due to
carbon cycle feedbacks in a coupled climate model, Nature, 408, 184-
\58\ For example, see Watson, R.T., J. Patz, D.J. Gubler, E.A.
Parson, and J. H. Vincent, 2005: Environmental health implications of
global climate change, Journal of Environmental Monitoring, 7, 834-843,
and Hunter, P. R., 2003: Climate change and waterborne and vector-borne
disease, Journal of Applied Microbiology, 94, 37S-46S.
\59\ Beggs, P.J., and H.J. Bambrick, 2005: Is the global rise of
asthma and early impact of anthropogenic climate change? Environmental
Health Perspectives, 113, 915-919.
\60\ For a given level of pollution, higher temperatures accelerate
the rate of formation of photochemical smog.
Senator Vitter. Thank you very much, Doctor.
And, Dr. Reiter, welcome.
STATEMENT OF PAUL REITER, CHIEF, INSECTS AND INFECTIOUS DISEASE
UNIT; PROFESSOR, INSTITUT PASTEUR
Dr. Reiter. Thank you, Senator Lautenberg, Senator Stevens,
Mr. Chairman, Members of the Committee.
I am a specialist in the natural history and biology of
mosquitoes, the epidemiology of the diseases they transmit, and
strategies for their control. I worked, for 22 years, for the
Centers for Disease Control and Prevention, CDC, including 2
years as a research scholar at Harvard. I am a member of the
World Health Organization Expert Advisory Committee on Vector
Biology and Control. I have directed many entomological
investigations of outbreaks of mosquito-borne disease and
others, such as Ebola hemorrhagic fever. I was a lead author of
the U.S. National Assessment of the Potential Consequences of
Climate Variability and Change. I'm presently professor of
medical entomology at the Institut Pasteur, in Paris, France.
In this presentation, I restrict my comments to my own
field, to malaria, and I will want to emphasize to you four
points. First of all, that malaria is not an exclusively
tropical disease. Second of all, the transmission dynamics of
the disease are complex, and the interplay of climate, ecology,
mosquito biology, mosquito behavior, and many other factors
defies simplistic analysis. It is--third, it is facile to
attribute the current resurgence of the disease to climate
change or to use models based on temperature to predict future
prevalence. And, last, many environmental activists are using
the ``big talk'' of science to create a simple, but very false,
paradigm. Specialists, like myself, who protest this paradigm
are generally ignored or are labeled ``skeptics.''
In the early 1990s, malaria topped the list of dangerous
impacts of global warming. The disease was going to move to
rich countries in the temperate regions as temperatures
increased. This prediction ignored the fact that malaria was
once an important cause of morbidity and mortality throughout
most of the United States and Europe, even in the period that
our climatology colleagues have called the Little Ice Age. In
the United States, as in Western Europe, despite a steadily
warming climate, prevalence of malaria declined in the 19th
century as a result of multiple changes in agriculture,
lifestyle that affected the abundance of mosquitoes, their
contact with people, and the availability of antimalarial
drugs. Nevertheless, the most catastrophic epidemic of all time
on record anywhere in the world occurred in the Soviet Union in
the 1920s, with a peak incidence of 13 million cases per year
and 600,000 deaths. Transmission was high in many parts of
Siberia, and there were 30,000 cases and 10,000 deaths in
Archangel, close to the Arctic Circle. The disease persisted in
many parts of Europe until the advent of DDT. Clearly here,
temperature was not a limiting factor in the distribution or
prevalence of malaria.
In the mid-1990s, activist emphasis changed to the
transmission of malaria in poorer countries, often referred to
as ``those least able to protect themselves,'' particularly in
sub-Saharan Africa. Yet in most of Africa, temperatures are
already far above the minimum required for transmission. In
addition, in most sub-Saharan Africa, transmission is termed
``stable,'' because people are already exposed to many
infective bites, sometimes more than 300 per year. So, annual
incidence is fairly constant. Mortality is highest in the
newcomers, young children and immigrants. Those that survive
acquire a partial immunity that reduces the risk of fatal
In other regions, transmission is endemic, but termed
``unstable,'' because annual transmission is variable. In these
regions, the potential for epidemics is much higher, because
immunity declines in periods of low transmission. Climatic
factors, particularly rainfall, are sometimes, but by no means
In recent years, activist emphasis has shifted to highland
malaria, particularly in East Africa. Despite carefully
research articles by malaria specialists, there has been a
flurry of articles by nonspecialists who claim an increase in
the altitude of malaria transmission that is already
attributable to warming and quote models that predict further
increase in the next 50 years. Tellingly, these people rarely,
if ever, give any detail of the views of specialists who
challenge them, nor do they mention that maximum altitudes for
transmission in the period from 1880 until 1945 were 500 to
1,500 meters higher than in the areas that are quoted as
examples. And, in any case, highland above 2,000 meters
constitutes a mere 1.3 percent of the whole continent, an area
about the size of Poland, totally dwarfed by regions of stable
and unstable transmission at lower altitudes.
An exasperating aspect of the debate is that this spurious
science is endorsed in the public forum by influential panels
of experts. I refer particularly to the Intergovernmental Panel
on Climate Change. Every 5 years, this U.N.-based organization
publishes a consensus of the world's top scientists in all
aspects of climate change. Quite apart from what we consider to
be the rather dubious process by which these scientists are
selected, consensus, sir, is the stuff of politics and not of
science. Science proceeds by observation, hypothesis, and
experiment. The complexity of this process and the
uncertainties involved are a major obstacle to meaningful
understanding of scientific issues by the lay public. In
reality, a genuine concern for mankind and the environment
demands the inquiry, accuracy, and skepticism that are
intrinsic to authentic science. A public that is unaware of
this is vulnerable to abuse.
The current increase in malaria is alarming, but the
principal factors involved are deforestation, new agricultural
practices, population increase, urbanization, poverty, civil
conflict, war, AIDS, resistance to antimalarials, and
resistance to insecticides. In my opinion, we should give
priority to a creative and organized effort to stem the
burgeoning tragedy of uncontrolled malaria, rather than
worrying about the weather.
Thank you for the honor of having spoken here.
[The prepared statement of Dr. Reiter follows:]
Prepared Statement of Paul Reiter, Chief, Insects
and Infectious Disease Unit; Professor, Institut Pasteur
Malaria in the Debate on Climate Change and Mosquito-borne Disease
I am a specialist in the natural history and biology of mosquitoes,
the epidemiology of the diseases they transmit, and strategies for
their control. I worked for 22 years for the Centers for Disease
Control and Prevention (CDC), including 2 years as a Research Scholar
at Harvard. I am a member of the World Health Organization Expert
Advisory Committee on Vector Biology and Control. I have directed many
investigations of outbreaks of mosquito-borne disease, and of others
such as Ebola Haemorrhagic Fever. I was a Lead Author of the U.S.
National Assessment of the Potential Consequences of Climate
Variability and Change. I am presently Professor of Medical Entomology
at the Institut Pasteur in Paris, France.
In this brief presentation I restrict my comments to malaria, and
emphasize four points:
1. Malaria is not an exclusively tropical disease.
2. The transmission dynamics of the disease are complex; the
interplay of climate, ecology, mosquito biology, mosquito
behavior and many other factors defies simplistic analysis.
3. It is facile to attribute current resurgence of the disease
to climate change, or to use models based on temperature to
``predict'' future prevalence.
4. Environmental activists use the ``big talk'' of science to
create a simple but false paradigm. Malaria specialists who
protest this are generally ignored, or labelled as
In the early 1990s, malaria topped the list of dangerous impacts of
global warming; the disease would move to temperate regions as
temperatures increased. This prediction ignored the fact that malaria
was once an important cause of morbidity and mortality throughout most
of the U.S. and Europe, even in a period that climatologists call the
``Little Ice Age.'' In the US, as in western Europe, prevalence
declined in the 19th century as a result of multiple changes in
agriculture and lifestyle that affected the abundance of mosquitoes,
their contact with people, and the availability of anti-malarial drugs.
Nevertheless, the most catastrophic epidemic on record anywhere in the
world occurred in the Soviet Union in the 1920s, with a peak incidence
of 13 million cases per year, and 600,000 deaths. Transmission was high
in many parts of Siberia, and there were 30,000 cases and 10,000 deaths
in Archangel, close to the Arctic circle. The disease persisted in many
parts of Europe until the advent of DDT. Clearly, temperature was not a
limiting factor in its distribution or prevalence.
In the mid-1990s, activist emphasis changed to transmission in
poorer countries, often referred to as those ``least able to protect
themselves,'' particularly in sub-Saharan Africa. Yet in most of the
continent, temperatures are far above the minimum required for
transmission, and most of sub-Saharan Africa, transmission is termed
``stable'' because people are exposed to many infective bites,
sometimes more than 300 per year, so annual incidence is fairly
constant. Mortality is highest in ``newcomers''--young children and
immigrants. Those that survive acquire a partial immunity that reduces
the risk of fatal illness. In other regions, transmission is endemic
but `unstable' because annual transmission is variable; the potential
for epidemics is great because immunity declines in periods of low
transmission. Climatic factors, particularly rainfall, are sometimes--
but by no means always--relevant.
In recent years, activist emphasis has shifted to ``highland
malaria,'' particularly in East Africa. Despite carefully researched
articles by malaria specialists, there has been a flurry of articles by
non-specialists who claim a recent increase in the altitude of malaria
transmission attributable to warming, and quote models that ``predict''
further increase in the next 50 years. Tellingly, they rarely quote the
specialists who challenge them. Nor do they mention that maximum
altitudes for transmission in the period 1880-1945 were 500-1500m
higher than in the areas that are quoted as examples. Moreover,
highland above 2000m constitutes a mere 1.3 percent of the whole
continent, an area about the size of Poland that is totally dwarfed by
regions of stable and unstable transmission at lower altitudes.
A galling aspect of the debate is that this spurious ``science'' is
endorsed in the public forum by influential panels of ``experts.'' I
refer particularly to the Intergovernmental Panel on Climate Change
(IPCC). Every 5 years, this UN-based organization publishes a
`consensus of the world's top scientists' on all aspects of climate
change. Quite apart from the dubious process by which these scientists
are selected, such consensus is the stuff of politics, not of science.
Science proceeds by observation, hypothesis and experiment. The
complexity of this process, and the uncertainties involved, are a major
obstacle to meaningful understanding of scientific issues by non-
scientists. In reality, a genuine concern for mankind and the
environment demands the inquiry, accuracy and skepticism that are
intrinsic to authentic science. A public that is unaware of this is
vulnerable to abuse.
The current increase in malaria is alarming, but the principal
factors involved are deforestation, new agricultural practices,
population increase, urbanization, poverty, civil conflict, war, AIDS,
resistance to anti-malarials, and resistance to insecticides, not
climate. In my opinion, we should give priority to a creative and
organized effort to stem the burgeoning tragedy of uncontrolled
malaria, rather than worrying about the weather.
The Lancet Infectious Diseases, Vol. 4, June 2004
Reflection & Reaction--Global Warming and Malaria: a Call for Accuracy
For more than a decade, malaria has held a prominent place in
speculations on the impacts of global climate change. Mathematical
models that ``predict'' increases in the geographic distribution of
malaria vectors and the prevalence of the disease have received wide
publicity. Efforts to put the issue into perspective \1\-
\5\ are rarely quoted and have had little influence on the political
debate. The model proposed by Frank C Tanser and colleagues \6\ in The
Lancet and the accompanying Commentary by Simon Hales and Alistair
Woodward \7\ are typical examples.
The relation between climate and malaria transmission is complex
and varies according to location,\2\ yet Tanser et al base their
projections on thresholds derived from a mere 15 African locations.
Slight adjustments of values assigned to such thresholds and rules can
influence spatial predictions strongly.\8\ The authors invest
considerable effort in assessments of the sensitivity of their model,
at the expense of defining the internal sensitivities of their
thresholds and rules. The predictive skill of their model is low (63
percent sensitivity, 95 percent CI 61-65 percent) but they consider
projections acceptable if prevalence is projected ``to within a month''
(presumably +/- 1 month?), thereby biasing their model toward success.
A model covering an entire year in a parasite-positive site would
always be correct, although in such areas it would be relatively
insensitive to climate. By contrast, sites in which transmission is
seasonal would provide a more reliable test of accuracy, but estimation
is more difficult because climate sensitivity is greater. Furthermore,
because parasite clearance in communities is not instantaneous,\9\ spot
samples of parasitaemia on survey dates are not a suitable indicator of
the duration of the transmission season. Last, ``person/months'' are
unsuitable as a measure of transmission: an extension of season from 1
to 4 months will have more impact than from 10 to 12 months. According
to their model, an extension of transmission from 11 to 12 months
results in 10 \6\ more person/months in a population of 10 \6\ people,
whereas an extension from 1 to 5 months gives the same increase in a
population of 250,000.
What Tanser and colleagues have modelled is merely the duration of
the transmission season, which they interpret as ``heightened
transmission'' and increased incidence. A greater failing is their
reliance on ``parasiteratio studies.'' The relations between
transmission season and parasite prevalence, and parasite prevalence
and clinical disease, are unclear but unlikely to be linear. Moreover,
they use 1995 data for human populations, although these are projected
to double by 2030. In addition, the proportion living in urban areas--
with a specific climate \10\ and orders of magnitude less malaria
transmission \11\, \12\--is projected to rise from 37
percent to 53 percent.\13\ For all these reasons, we do not accept the
model as a ``baseline against which interventions can be planned.''
It is regrettable that many involved in this debate ignore the rich
heritage of literature on the subject. For example, in 1937, in his
classic textbook,\14\ L W Hackett stated: ``Everything about malaria is
so moulded and altered by local conditions that it becomes a thousand
different diseases and epidemiological puzzles. Like chess, it is
played with a few pieces, but is capable of an infinite variety of
situations.'' A pressing question in Hackett's time was the changing
distribution of the disease in Europe. On the role of climate, he
wrote: ``Certainly, climate lays down the broad lines of malaria
distribution . . . Nevertheless, although this is a very simple and
plausible explanation . . . even the early malariologists (sic) felt
that there was something unsatisfactory about it . . . malaria has not
so much receded as it has contracted, oftentimes toward the north . . .
Thus in Germany it is the northern coast which is still malarious, the
south is free . . . There is, therefore, no climatic reason why
(malaria) should have abandoned south Germany or the French Riviera.''
We quote Hackett because we feel that the classic components of
science--unbiased observation and systematic experimentation--cannot be
sidestepped with models that omit many of his chess pieces. Yet Hales
and Woodward \7\ begin by stating: ``The present geographical
distribution of malaria is explained by a combination of environmental
factors (especially climate) and social factors (such as disease-
control measures).'' In our opinion, ``even the early malariologists''
would surely disagree: much of the decline of malaria in Europe took
place without control measures during a period when the climate was
The text by Hales and Woodward that follows displays a lack of
knowledge. Thus, ``Most people at risk of malaria live in areas of
stable transmission . . . '' is simply wrong. It is true that in many
parts of the world malaria is termed ``stable'' because transmission
remains relatively constant from year to year, the disease is endemic,
the collective immunity is high, and epidemics are uncommon. However,
in many other regions, the disease is endemic but ``unstable'' because
annual transmission varies considerably, and the potential for
epidemics is great. Climatic factors, particularly rainfall, are
sometimes, but by no means always, relevant.\15\
Again, ``On the fringes of endemic zones, where transmission is
limited by rainfall . . . there are strong seasonal patterns, and
occasional major epidemics'' is also wrong. In many regions, far from
any ``fringes,'' malaria is endemic, stable, but highly seasonal. For
example, in semi-arid regions of Mali, transmission is restricted to
the rainy season, from July to September. The same 3 months constituted
the transmission season for Plasmodium falciparum in Italy before it
was eliminated.\16\ Paradoxically, in parts of the Sudan, rainfall is
restricted to a month at most, but malaria is transmitted throughout
the year. Female Anopheles gambiae survive severe drought and extreme
heat by resting in dwellings and other sheltered places.\17\ Blood
feeding and transmission continue, but the mosquitoes do not develop
eggs until the rains return. This phenomenon, termed gonotrophic
dissociation, is remarkably similar to the winter survival strategy of
Anopheles atroparvus, the principal vector of malaria in Holland until
the mid 20th century.\16\
By contrast, malaria is unstable in many regions that normally have
abundant rainfall, and epidemics occur during periods of drought. An
illustrative example is the catastrophic 1934-1935 epidemic in Ceylon
(now Sri Lanka), estimated to have killed 100,000 people.\18\ Worst hit
was the southwestern quadrant of the country, where average annual
rainfall is greater than 250 cm, and malaria was endemic, but unstable
and relatively infrequent. The dominant vector, Anopheles culicifacies,
breeds along the banks of rivers and tends to be scarce in normal
years. In the years 1928-1933 there was abundant rainfall, river flow
was high, An culicifacies was rare, and the human population was
exceptionally malariafree. However, after failure of two successive
monsoons, the drying rivers produced colossal numbers of An
culicifacies, and the resulting epidemic was exacerbated by the low
collective immunity. In the drier parts of the island, where An
culicifacies was dominant but transmission was more stable, immunity
protected the population from the worst ravages of the disease.
Hales and Woodward state that ``the underlying problem'' of the
future ``extension of seasonality'' of malaria is ``pollution of the
atmosphere'', and call for rich countries to ``recognise their
obligations to the poorest by substantially reducing fossil-fuel
consumption.'' We understand public anxiety about climate change, but
are concerned that many of these muchpublicised predictions are ill
informed and misleading. We urge those involved to pay closer attention
to the complexities of this challenging subject.
Paul Reiter, Christopher J Thomas, Peter M Atkinson, Simon I
Hay, Sarah E Randolph, David J Rogers, G Dennis Shanks, Robert
W Snow, and Andrew J Spielman.
PR is professor of medical entomology, Institut Pasteur, Paris,
France; CJT is senior lecturer in spatial ecology and Wolfson
Institute fellow in health and environment, School of
Biological and Biomedical Sciences, University of Durham, UK;
PA is professor of geography, University of Southampton, UK;
SIH is a Wellcome Trust research fellow, SER is professor of
parasite ecology, and DJR is professor of ecology, Department
of Zoology, University of Oxford, UK; GDS is at the U.S. Army
Centre for Health Promotion and Preventive Medicine, MD, USA;
RWS is professor of tropical public health, University of
Oxford; AJS is professor of tropical public health, immunology
and infectious diseases, Harvard School of Public Health,
Boston, MA, USA. SIH and RWS are also at the KEMRI Wellcome
Trust collaborative programme, Kenya.
\1\ Reiter P. From Shakespeare to Defoe: malaria in England in the
little ice age. Emerg Infect Dis 2000; 6: 1-11.
\2\ Reiter P. Climate change and mosquito-borne disease. Environ
Health Perspect 2001; 109 (suppl 1):141-61.
\3\ Hay SI, Cox J, Rogers DJ, et al. Climate change and the
resurgence of malaria in the East African highlands. Nature 2002; 415:
\4\ Shanks GD, Hay SI, Stern DI, Biomndo K, Snow RW. Meteorologic
influences on Plasmodium falciparum malaria in the highland tea estates
of Kericho, Western Kenya. Emerg Infect Dis 2002; 8: 1404-08.
\5\ Rogers DJ, Randolph SE. The global spread of malaria in a
future, warmer world. Science 2000; 289: 1763-66.
\6\ Tanser FC, Sharp B, le Sueur D. Potential effect of climate
change on malaria transmission in Africa. Lancet 2003; 362: 1792-98.
\7\ Hales S, Woodward A. Climate change will increase demands on
malaria control in Africa. Lancet 2003; 362: 1775.
\8\ Thomas CJ, Davies G, Dunn CE. Mixed picture for changes in
stable malaria distribution with future climate in Africa. Trends
Parasitol 2004; 20: 216-20.
\9\ Smith T, Charlwood JD, Kihonda J, et al. Absence of seasonal
variation in malaria parasitaemia in an area of intense seasonal
transmission. Acta Trop 1993; 54: 55-72.
\10\ Arnfield A. Two decades of urban climate research: a review of
turbulence, exchanges of energy and water, and the urban heat island.
Int J Climatol. 2003; 23: 1-26.
\11\ Snow R, Trape J, Marsh K. The past, present and future of
childhood malaria mortality in Africa. Trends Parasitol 2001; 17: 593-
\12\ Robert V, Macintyre K, Keating J, et al. Malaria transmission
in urban sub-Saharan Africa. Am J Trop Med Hyg 2003; 68: 169-76.
\13\ United Nations. World urbanization prospects: the 2001
revision. Data tables and highlights. New York: United Nations, 2002.
\14\ Hackett LW. Malaria in Europe, an ecological study. London:
Oxford University Press, 1937.
\15\ Gilles HM, Warrell DA, eds. Bruce-Chwatt's essential
malariology. London: Edward Arnold, 1993.
\16\ Bruce-Chwatt LJ, de Zulueta J. The rise and fall of malaria in
Europe, a historico-epidemiological study. Oxford: Oxford University,
\17\ Omer SM, Cloudsley-Thompson JL. Survival of female Anopheles
gambiae Giles through a 9-month dry season in Sudan. Bull World Health
Organ 1970; 42: 319-30.
\18\ Dunn C. Malaria in Ceylon: an enquiry into its causes. London:
Bailliere, Tindall and Cox, 1937.
These articles are in committee files and can be found at their
Climate Change and Mosquito-Borne Disease, Paul Reiter,
Environmental Health Perspectives, Vol. 109, Supplement 1:
Reviews in Environmental Health, 2001 (Mar., 2001), pp. 141-
From Shakespeare to Defoe: Malaria in England in the Little Ice
Age, Paul Reiter
Emerging Infectious Diseases, Vol. 6, No. 1, January-February
Senator Vitter. Thank you very, very much, Doctor. I'll
kick off the questioning.
Dr. Corell. Yes.
Senator Vitter.--I wonder if you could put up one of your
first slides, which was the temperature chart, because I'm
trying to understand it, in part, by----
Dr. Corell. Sure.
Senator Vitter.--comparing it to Dr. Armstrong's figure 1.
Are you familiar with Dr. Armstrong's----
Dr. Corell. I am not----
Dr. Corell.--but I'd be happy to have a look at it. Yes,
OK. I now know what----
Senator Vitter. Right. Your----
Dr. Corell. This----
Senator Vitter.--chart basically goes back to----
Dr. Corell. This is 2,000 years.
Senator Vitter.--2,000 years. Dr. Armstrong's figure 1 is
much more long term, I think.
Dr. Corell. That's correct.
Senator Vitter. It goes back 400,000 years.
Dr. Corell. Right.
Senator Vitter. And so, I guess the comparison--the
conclusion from the comparison is--and correct me if I'm
wrong--that the Earth has experienced similar temperature
levels to the present day, but much further back than 2,000
Dr. Corell. That's correct. And I would say it's the
CO2 that is way above the record, certainly in the
record that's in his testimony, but there are several papers
that suggest that we have not had these CO2 levels
for 25 million years.
Senator Vitter. Right. And his chart also suggests that,
Dr. Corell. Right.
Senator Vitter.--you're looking at it----
Dr. Corell. That's----
Senator Vitter.--his chart of CO2 and
Dr. Corell. Are well----
Senator Vitter.--way beyond----
Dr. Corell.--well beyond the----
Senator Vitter.--anything in the last 400,000 years. And
Dr. Corell. And----
Senator Vitter.--provoked my question----
Dr. Corell. Yes, about----
Senator Vitter.--which is----
Dr. Corell.--the lead-lag issue.
Senator Vitter. Right.
Dr. Corell. Let me say a word or two about it and go to
another slide here, if I can, and that's this one. As this
imbalance of heat comes into the system, and the ocean observe
it--absorbs it, it's going to re-radiate that and heat--and
reheat the atmosphere. But this out-of-balance is due to the
CO2 level being much higher, creating the greenhouse
effect. And so, there's--during a time when we have both
natural variability and human-induced variability, or human-
induced warming, during that time the temperature is going to
lag behind the rise in CO2. Do you follow that, from
Senator Vitter. Now, why is that different from a period
where it's a purely natural process?
Dr. Corell. Because--well, several reasons. One, there's a
much slower rate of warming occurring in--during the natural
process period. And, quite frankly, if you look at this
400,000-year record, it's pretty hard to sort out the lead-lag
relationship. In fact, some will argue that it--sometimes
temperature leads the CO2 and other times it lags
the CO2, and that's probably due to a bunch of--a
whole group of natural processes. A lot of them are the
wobbling and the precessions of the planet and so on. But what
I want to make--the difference is that we are in a region now
where we have clearly natural variability, and, on top of that,
we have the human-induced increase in CO2, and that
human-induced in CO2 is likely to cause the
temperature to lag behind the CO2 rise.
So, the answer to your question, in my judgment, is that we
are going to see a continued rise in temperature. Most recent
meeting in the U.K. held by John Shellnhuber and the group on
the dangerous intervention issue, concluded that as we sit
here, we're likely to see 2 to 3 degrees of warming,
Centigrade, during this coming century. So, whether--we
definitely will have a rise in temperature, given the rate at
which CO2 is increasing today.
Senator Vitter. Dr. Akasofu, do you have any reaction or
Dr. Akasofu. No, on this particular point, because as Dr.
Corell mentioned, all the changes are going on. Climate change
is going on, definite. No question about that. And the only
thing we are trying to find is which portion is natural, which
Senator Vitter. Right.
Dr. Akasofu. From our study, we--the--we cannot tell.
Senator Vitter. Right.
I want to go to Dr. Akasofu's figure 1, which is really
interesting to me. His basic explanation of the dip in both
Arctic and the smaller dip in global temperature between 1940
and 1970 is that you have major natural factors, as well as
manmade. What would be your explanation, Dr. Corell?
Dr. Corell. Well, I think there are times when a--the--in
this early part of the rise in temperature, where the natural
variability can override. And we will see--I think the general
consensus of the literature is that that relative cooling--
relative cooling that occurred in--as Dr. Akasofu has pointed
out--has--was due to a natural variability factor. But now I
think we can see from the record, certainly in the last half a
century, that the IPCC and much of the literature will indicate
that the predominant factor of the warming is coming from
human-induced CO2 contributions to the atmosphere.
Senator Vitter. How do they reach that conclusion? How do
they parcel out natural versus human?
Dr. Corell. Well, one way to do it--there are several--one
is to take your models--and I would like to talk a little about
the models, because you asked a very good question about that--
and ask yourself, How could we get the temperature that we have
today? And we have a pretty good idea of solar variability over
the last 50 to 100 years. We have a clear idea of what volcanic
eruptions are. Those are--you know, those are cooling effects.
In other words, we have a pretty good idea of the major
contributing factors. If you try to get the temperature that we
have today without the human-induced factor, you just can't get
there. And there have been numerous papers that do this.
Now, we're talking at the global scale. And I think----
Senator Vitter. May I interrupt for a second?
Dr. Corell. Yes.
Senator Vitter. Why can't you get there, since,
historically, Earth has been there?
Dr. Corell. Well, the conditions of the past at which it
got there were quite different than the ones we have today. I
mean, there are times when we've had much warmer regions of the
Arctic there. You know, we had mastodons running around in a
much warmer--a much warmer set of conditions.
What we're talking about here is, What's changing the
conditions now, over the last, well, let's say 2 and a half
million years, when we have had the glaciation periods with all
these cycles occurring? During that time, we could not get to
the temperatures we've gotten today--I mean, the CO2
and temperatures we've got today--without having CO2
being put into the atmosphere by humans.
Senator Vitter. Well, again, doesn't Dr. Armstrong's figure
1 suggest otherwise with regard to temperature, not
Dr. Corell. Well, he's not only talking about--Dr.
Armstrong's--yes. Try me again. I was thinking of Dr. Akasofu's
Senator Vitter. No, no, that other figure----
Dr. Corell. Oh, I----
Senator Vitter.--the one----
Dr. Corell.--I know which one you're talking--I just
Senator Vitter. Doesn't that----
Dr. Corell.--your question.
Senator Vitter.--suggest, contrary to what you just said,
that you can't get there otherwise with regard to temperature,
not--I mean CO2 levels, clearly----
Dr. Corell. CO2, methane----
Senator Vitter.--all-time high----
Dr. Corell. Right.
Senator Vitter.--nothing. But temperature level is not, at
Dr. Corell. At this stage, we're at about the level--the
maximum levels we've seen during the glacial period of the last
million or 2 million years, that's correct. But what I'm
suggesting is that we already know there's more temperature
buried in the ocean to come out from CO2 already put
in the atmosphere by humans during the past 10, 20, 30 years,
so that the future----
Senator Vitter. Well, but that is----
Dr. Corell.--will be warm.
Senator Vitter.--that conclusion assumes that CO2
is driving--the single factor or predictor.
Dr. Corell. Well, I think the physics on that is pretty
clear, that CO2 and the greenhouse gases do trap the
energy between the upper atmosphere and the ground, and warm
the planet. I think that's--the physics on that's clear.
I'm maybe not getting your point, sir.
Senator Vitter. Well, again, it seems to me, in terms of
the historical record, you're sort of assuming that CO2
is the perfect predictor and overrides anything else.
Dr. Corell. Well, I think if you do the physics on CO2
and the other greenhouse gases, they will trap the energy
between the upper atmosphere and the ground, and will warm the
planet. And what is clear to us now is, the ocean has enough
information--enough heat in it to warm the planet beyond
anyplace we have been over the last, say, 400,000 years.
Senator Vitter. Dr. Akasofu, obviously the Arctic is an
extreme case compared----
Dr. Akasofu. Yes.
Senator Vitter.--to global situations.
Dr. Akasofu. That's correct.
Senator Vitter. Now, that could suggest that it's the
perfect place to study, because it is--shows a heightened level
of trends that are global, or it--maybe it could suggest the
opposite, that it's sort of an anomaly. What's your conclusion
about that basic question?
Dr. Akasofu. It goes--the Antarctic, as you said, is an
signal magnitude or amplitude is at least three times bigger.
So, so much easier to study. And, furthermore, what really--in
this latitude, you don't see .6 degree temperature change
what's happening, but Arctic, you can see all kinds of----
Senator Vitter. Right.
Dr. Akasofu.--climatic--climate changes going on. So, the
Arctic is, to me, the place we should study. That's--there is
no disagreement with----
Dr. Corell. No, no----
Dr. Akasofu.--Dr. Bob Corell, yes. But the--Dr. Corell says
yes, physics of the CO2 is greenhouse gas. Our
question is, quantitatively, how many degrees, and where? And
the observations show that the actual largest, most prominent
warming taking--that was taking place in the continental
Arctic. But somehow the IPCC computer could not produce that.
And that means, to me, it's something else. And we found that
it is something else, not the greenhouse effect. So, we have to
be very careful here.
Senator Vitter. I'm glad you mentioned that, because it
goes back to some of the testimony from the first panel, where
they suggested that some of the very recent work, including a
publication in Nature very recently, fine-tuned some of the
climatic models in such a way that it was very predictive,
looking back to what we have measured historically. Can you
react to that?
Dr. Akasofu. Sorry, I don't think so at this time. I--our
interest is try to understand the increase from 1920 to 1940--
Senator Vitter. Right.
Dr. Akasofu.--and then the decrease from 1940 to 1970.
Unless we understand that, we don't think we understand the
increase from 1970 on.
Senator Vitter. Right.
Dr. Akasofu. Yes.
Senator Vitter. Let me ask it a different way. How good and
perfected do you think the current climatic models are, in
terms of temperature prediction, if you test it against that
bit of history?
Dr. Akasofu. I believe that there are all kinds of
complexities there, but the general pattern, to me, that
computers should be able to produce--I mean, we have advanced
so much in our simulators, all kinds of a major supercomputers
working, so I trust that, at least, you know, some aspects
should be--you know, computer should reproduce. And if the
computers cannot reproduce--and, you know, that was the basis
for the Kyoto Protocol.
Senator Vitter. Right.
Dr. Akasofu. And if you say the computers are no good, then
we have to abandon the Kyoto Protocol, too. So,----
Senator Vitter. Right.
The Chairman. Thank you.
Dr. Akasofu, at your request we authorized funding for
further temperature measurements in the Arctic Ocean over the--
what, the last 3 years? How many years?
Dr. Akasofu. Yes.
The Chairman. And there--have you had any tentative
conclusions from those temperatures as to whether there is
noticeable change now, as far as the temperature of the Arctic
Dr. Akasofu. Yes. The--what's happening is that the warm
North Atlantic water is intruding into the Arctic Ocean, and we
are tracing this water. It's moving around Siberian coast, and
then moving toward Alaska. So, although it's a very complicated
thing, but suddenly tremendous heat is coming from the North
Atlantic into the Arctic Ocean, which is, I'm sure, the partial
reason for the ice melting there.
The Chairman. And is that in any way related to the recent
intensity of the sun's heat, as far as the Atlantic Ocean is
Dr. Akasofu. That, I can't tell. We just learned that--in
the last paper, that as much as 30 to 40 percent of temperature
increase could have been due to just the solar output increase.
But we have to now go back and look at the computer modeling
and put it in that and see if that will warm up North Atlantic
or not. We have not done that yet.
The Chairman. And this--we have your statement, and figure
6 showing the distribution of that Atlantic water, the so-
called Atlantic oscillation. How long has that been going on,
do you know?
Dr. Akasofu. Oh, as far as we determine, you know, it's at
least 50--accurately, the last 50-60 years over good data--what
we call NAO, North Atlantic oscillation, intensity changes, and
we know that.
The Chairman. Well, is that warming of the Arctic Ocean
related to some of the change we see in our State now, as far
as the permafrost and basic change in the climate?
Dr. Akasofu. OK, that's--our scientists have--different
scientists have a different point of view. The continental
portion of warming, they think that could be something else.
But the--they are not sure yet.
The Chairman. By that, you mean what's happening in the
Arctic Ocean could be both natural and manmade.
Dr. Akasofu. I think so.
The Chairman. How long a period do we have to study that to
reach a--any tentative conclusion on it?
Dr. Akasofu. The--in the past--I think--this is my view--
that people are aware that the--there are natural and manmade,
both components, but not many people really spent the time to
separate those out. It's very difficult. Whenever there is--we
should make the effort. And we are now concentrating--some of
us really working hard to do that particular job, rather than
study with just the North Atlantic water coming in or something
The Chairman. Have you flown over the Arctic area recently?
Dr. Akasofu. Not recently, not last year or so.
The Chairman. I took one flight--this'll be my last
comment--over--coming from the West Coast, going over to
Barrow, and it was pointed out to me the places where the ocean
had been up far inland from where it is now. And the pilot
indicated that it showed that while we think the water is
rising now, it hasn't come up near where it was in years--many
years gone by.
Dr. Akasofu. Yes.
The Chairman. Now, are you able to study those other areas
and see what the fluctuation has been, in terms of the Arctic
Ocean's intrusion upon the Alaska part of our continent?
Dr. Akasofu. Some of us are studying the ocean conditions
or land--the features from the last Ice Age, not before that.
But I think our people are collecting lots of data from during
the last age, can see the major changes. And also even during a
little ice age we had from 1300 to 1800, some major changes in
terms of glaciers advance and retreat.
The Chairman. I don't know if my colleagues had a chance to
read the statement you've got--that you've submitted, but very
clearly I take it that the impact that you're trying to leave
with us, is, we don't know enough yet to make a judgment as to
what part of this is manmade and what part is natural.
Dr. Akasofu. I think I agree with Dr. Armstrong. We are
trying, trying. This is very hard. And perhaps IPY,
International Polar Year, when some scientists concentrate on
this, we may make good progress.
The Chairman. Thank you very much.
Senator Vitter. Thank you.
The Chairman. I want to thank the others, too, also, but I
have to go to a meeting. I don't want to prolong this right
Senator Lautenberg. Mr. Chairman, I'm a little confused
here with something--some of the things that are said. And I
ask Dr. Akasofu, Are you aware of any peer-reviewed science
study that's said--or asserted that the present warming in the
Arctic or globally is entirely due to human-caused global
Dr. Akasofu. It's--I believe that is more of the press
takes that view, but most scientists agree that there are two
components, those manmade----
Senator Lautenberg. I understand that, sir. I just want to
be sure, because as I read your paper I had the--I drew the
understanding that you ascribe most of this to human-caused
global warming, and that the natural phenomena, the natural
changes that are caused, are not something to be as concerned
about. And now you do say there's a division, that there--it--
the--both areas result in these changes that we're seeing. The
changes are obvious. You've confirmed that in your----
Dr. Akasofu. Yes.
Dr. Akasofu. Right. No question.
Senator Lautenberg. Yes.
Dr. Akasofu. Yes. Dr. Corell described it beautifully,
Senator Lautenberg. Yes.
Dr. Akasofu. The question is, How much is due to----
Senator Lautenberg. Yes. How much, Dr. Akasofu, would you--
do you think that we ought to get after those things that we
identify as caused by human existence, CO2? Is that
largely caused by human activities, or is that--is there any of
that, that comes from natural----
Dr. Akasofu. OK. In science--in scientific methodologies,
we assume, say, it is due to carbon dioxide, and then the--we
use a supercomputer--supercomputer behave like virtual Earth.
We put in CO2 into, and then calculate the result.
Senator Lautenberg. Yes.
Dr. Akasofu. And if the results agree with the
observations, then that is the way to confirm that----
Senator Lautenberg. Yes, I----
Dr. Akasofu.--it's CO2.
Senator Lautenberg. Forgive me for----
Dr. Akasofu. There is, so far----
Senator Lautenberg.--interrupting, but----
Dr. Akasofu. There is, so far, no confirmation yet.
Senator Lautenberg. Well, but--so, should we not intervene
in trying to reduce the human contribution to----
Dr. Akasofu. No, I am not saying that at all.
Senator Lautenberg. No, I know you're not saying that,
but--I'd like you to say that. But the thing is that--at what
point do you say--``you,'' I'm saying, generic ``you,'' lots of
people--say, ``Hey, we know that this is a phenomena that
portends bad things for the human race.'' And if we agree with
that, then I say, ``Well, what--at what point do we ask the
politicians''--Dr. Reiter said something about political hay
being made of this, as opposed to science. I'm going to ask you
about that. And so, at what point, Dr. Corell, does the alarm
sound loudly enough that says, ``Hey, let's stop destroying our
forests, let's stop emitting these carbon dioxide chemicals--or
results into the air''? At what point do we take care to join
in the protection of our environment and our lives?
Dr. Akasofu. There is no question that we have to--I don't
think we can ever reduce the total amount of carbon dioxide in
the air, but we should try to reduce the rate of increase.
Senator Lautenberg. Dr.----
Dr. Akasofu.--coming, India is coming----
Senator Lautenberg. Thank you.
Dr. Akasofu. Yes.
Senator Lautenberg. Dr. Corell?
Dr. Corell. Yes, I think it's pretty clear from the
assessments that the scientific community have put together, a
variety of them, whether it be IPC, national assessment of the
U.S. or Canada or other countries around the world, our recent
Arctic assessment clearly indicates that it's time for action.
And let me tell you why I believe so strongly it is time for
If we were wise enough to take our CO2 and
reduce it, like, over the next 100-150 years, OK--this is the
result of some model studies--it would take the planet about
200 years for the CO2 to stabilize at some higher
level, 700 or so, something--some number, quite a bit higher
than we are today. It'll take another 200 years, roughly, for
the temperature to stabilize. So, we're talking about 3- to 500
years before the planet's stabilized. This is if we act, and it
takes us 100 to 150 years to bring things down.
The real sleeper is that sea-level rise will continue for
probably 1,000 or more years, with those increased temperatures
that are a result of the higher levels of greenhouse gases. So,
if that's so--and we believe strongly, it is; this is IPCC
results that came out of our study, as well--it seems logical
that you ought to move that action time shorter to lower those
temperature rates and to reduce the time for the stabilization
So, I think the conventional wisdom within the scientific
community is that we know enough now to take appropriate
action. That's a political issue. That's an issue for you and
others like you, to figure out how you take those steps, but
we're trying to suggest to you, it is timely, and it is now
that such steps should----
Senator Lautenberg. Sure.
Dr. Corell.--be taken.
Senator Lautenberg. Yes, a recommendation is being clearly
made from the abundance--from the gathering of science--
scientific knowledge that we have now, that we ought to get on
with changing the pattern of what we see overtaking us, by
intervening in the emission of CO2--and, again, I
use deforestation as the example, but lots of things that we do
as humans that violate the chances for our environment to
succeed, as we know it.
Dr. Corell. Agreed.
Senator Lautenberg. Dr. Reiter--unfortunately, we're going
to have to rush through this--you use the equivalent of the
canary and the coal mine, in terms of malaria. And you know
what that example, traditional----
Dr. Reiter. Oh, they were British mines, I think.
Senator Lautenberg. Yes. So, you say that, and you don't
like the environmental activists using big talk of science to
create simple, but false, paradigms. We have every right--and
I'm not talking as a United States Senator, and I'm talking
about every right as a human being--to take what we hear and
take what we read and take the evidence that we see in front of
us, all kinds of indications that this world is a less
accommodating place than it was. And you--your closing comment,
I think, is one of the, kind of, more interesting, worrying
about the weather, ``Ah, don't worry about that.'' You're
right, why worry about a Katrina or a tsunami or frequency of
these storms and the ferocity of these storms, when malaria is
not shown to be anything that's produced that's essentially or
totally a tropical disease or--it doesn't indicate any real
growth over the years, with substantial reductions, but a
little spike. And you're a scientist, and a very well educated
one, but I think worrying about the weather, other than to--
buying an umbrella or something like that, is probably a good
idea. And so--and it's consistent with what we want to do here;
and that is, gather information that helps us spur some
activity. That's what we do. We're--we have the political
muscle to do things, unless it's counteracted by structure of
You know, I think that, you know, we have a suggestion now
that as--that gas prices are so high that we ought to break
environmental rules that exist now and get on with it, getting
that gasoline price down. As they say in my old schoolyard--I
grew up in a tough area--``It ain't gonna happen that way,'' I
can tell you. We can violate good environmental activities, and
it's not going to affect what we--what happens in gas prices.
We're--there's a whole other thing there.
And what we do here, as legislators, is react to things. We
rarely ever do anything that's creative in major magnitude
that's induced by other than a reaction to a--what happens. And
I was listening to these discussions about the hundreds of
years away, and--but we have an obligation to worry about those
hundreds of years away.
And when I see a report put out for the Navy that says,
``The Navy's got to be prepared in the second half of this
century to fight off refugees seeking higher land,'' we know
now people will get into tire tubes and chance trips with
shark-filled waters to get to this great country of ours. But
if people are going to be deluged by water--and we're talking
about places that are not so distant from us, not necessarily
Bangladesh, which is a--threatened, but the Netherlands and
places like that.
And, Mr. Chairman, you've experienced the worst of what
happened in the--when a storm hits and the water rises above
your capacity to contain it. So, we ought to get on with our
task. And I would hope that the scientists would scare us a
little bit and not let--let us feel too comfortable about,
``Well, natural causes.'' If there is a natural cause, there's
a natural cause, but if there isn't, then we ought to do
something about that share of it.
Dr. Reiter. May I answer your question?
Senator Lautenberg. Sure.
Dr. Reiter. First of all, I didn't mean to be flippant
about the importance of the weather. What--and, again, I chose
my own field as an illustration of problems of public health.
I'm very glad that you say that I'm well educated. I like
to think I could be better educated.
What I would urge you to do--and I would urge all of those
who are interested, at least in the health aspects of this
debate--is to look up the credentials, the scientific
credentials of the principal exponents--proponents, I'm sorry--
proponents of this disastrous situation, and compare them to
the credentials, scientific credentials, of those who are
essentially saying, ``Well, wait a moment. What are you saying?
We don't have--we don't have the evidence for this.'' And if
you look--I mentioned the IPCC, and I know that others have
talked about the IPCC in a different way. I can only talk in
the field of health. I can tell you, please look at----
Senator Lautenberg. So, you're critical of the IPCC.
Dr. Reiter. Yes. Well, hang on. May I finish? If you look
at the credentials of the lead authors----
Senator Lautenberg. Dr. Reiter, I must leave. And I don't
want to leave an empty chair and be disrespectful. So, I would
say this, that when the National Academy of Sciences
contributes their view, that there is pretty solid evidence
there, and other distinguished science groups. I say, ``Well,
OK, you might be wrong.''
Forgive me, I've got to go.
Senator Vitter. Dr. Reiter, please finish up. I'm all ears.
Dr. Reiter. Well--no, I don't want to continue about the
IPCC--that's a quite different issue--except to suggest that
you look at the credentials of the lead authors. You will find
that none of them--neither of them have any credentials in the
field of public health. And if you look back to the reports of
2001 and 1995, you will see exactly the same. You will find
that there are people there whose previous studies were on
motorcycle crash helmets and the effects of cellular telephones
on brain cancer. These are issues that really may be important,
but, when we are talking about public--important public-health
issues, we need to go to the people who specialize in public
Senator Vitter. Actually, I was going to ask you about the
IPCC, because I find it very interesting that both you and Dr.
Corell refer to it, in, of course, completely different ways.
I'd just ask you to follow up on your comments and your
testimony. The IPCC exercise, how driven do you think it is by
scientific rigor or politics and ideology?
Dr. Reiter. First of all, again, I can only speak for the
health chapter, Chapter 8. In my opinion, we have to remember
that this is the Intergovernmental Panel on Climate Change.
Those--you may notice that I added to my dossier for you a
paper--an article that nine of us, who consider ourselves
leading experts in our field, published in The Lancet. We
called it, ``A Call for Accuracy: Malaria and Climate Change.''
And, basically, none of us are on the panel--are on the Chapter
8 Panel. I can also tell you that I know of certain very highly
respected persons that were nominated by the U.S. Government
for lead authorship in Chapter 8 and were turned down in favor
of people--one person who has not a single scientific article
written in the whole career.
So, I think, at least in my field, yes, there is a strongly
biased selection of people, and I know, also, from people who
have been expert reviewers, that the expert--the review system
is very interesting. Normally in science, review is by
anonymous peer review. And the--in the IPCC, it is the
opposite. It is by nonanonymous peer review. The expert
reviewers discuss with the authors and come to so-called
consensus. Now, when we did the U.S. Government evaluation in--
about 5 years ago, it was the opposite, or, rather, those of
us--well, let me go on to what the real opposite was. The
discussions were public domain. You can actually find out what
those discussions were by looking on the Web. You cannot see
what the criticisms were of the authorship in the first and the
second draft of the health chapter. In other words, what I feel
is that a major investigation of the means by which the
conclusions of the IPCC, at least in my field, are drawn, is
Senator Vitter. Is it fair to say, then, that some of the
traditional methods brought to scientific publication, like
anonymous peer review, are abandoned in that U.N. process?
Dr. Reiter. Well, it certainly isn't anonymous peer review.
And it is very hard for those of us who are in this field--as I
mentioned before, it is very hard for us to make some sort of
scientific comment without either being ignored or being called
``skeptics,'' in a rather derogatory way.
What I tried to say, policymakers like yourself
increasingly depend on science for making policy. And, by the
way, scientists depend a great deal on policymakers for their
living. But in a democratic society, policymakers respond to
the public conceptions of these issues. We scientists are not
really very good at essentially communicating with the public;
or, rather, I think the public doesn't quite realize the way--
the difficulty there is in conveying the way that science
Public conceptions are essentially shaped by the press. We
scientists also find it very difficult to deal in a scientific
way with the press. The press normally picks up on those
things, as is obvious, that have, perhaps, the most extreme
implications on life on Earth.
On the other hand, those people who would like to speak on
behalf of scientists, whether they are scientists or not, have
a very much greater influence on the press, on public
conceptions, and, therefore, on policymaking. And this, I feel,
is not only in this field of climate change, but it also
applies to many other issues that have become controversial or
have become important in the way that policy is made.
Senator Vitter. Thank you very much.
Thanks to all of you. This has been quite significant and
lengthy and wide-ranging hearing. I appreciate all of your
testimony and participation. Again, several of you came from
quite a distance, we deeply appreciate that.
And, with that, the Subcommittee hearing is adjourned.
[Whereupon, at 5 p.m., the hearing was adjourned.]
A P P E N D I X
Prepared Statement of Hon. Daniel K. Inouye, U.S. Senator from Hawaii
In just the last few months a number of alarming new studies have
come out on the projected and observed effects of climate change. These
studies--and the testimony today--report that some projected climate
change impacts are already occurring, and these changes are taking
place at a faster pace than predicted.
Latest estimates foresee a warming of the Earth's temperature of
somewhere around five degrees by the end of the century. By 2100, sea
levels could be several feet higher than they are now, which would have
devastating effects on coastal areas, including my home State of Hawaii
and the other Pacific Island nations. We have already seen the powerful
destruction tsunami or severe weather can have on our low lying
islands, and this damage will be magnified under the National Oceanic
and Atmospheric Administration's (NOAA) projections of a one to three
foot rise in sea level.
Scientists also tell us that if trends continue as projected, we
will see an increase in the already alarming growth in ocean
acidification and coral bleaching events. These ocean changes would
have virtually irreversible impacts on the fisheries and tourism
industries and thus the Hawaiian economy. NOAA tells us that it took
80,000 years for ecosystems to recover from the last mass extinction
from ocean acidification.
As I have noted previously, I also have serious concerns about the
Administration's efforts to suppress or downplay the findings of
government scientists, particularly in this area of global climate
research. It is only through broad dissemination of their research and
public conversation that we can effectively tackle the causes of
climate change. We must have the benefit of a full and open scientific
assessment of the likely effects of climate change in the next 20 to 50
years, as already required by law. The Administration should not be
avoiding and suppressing our scientists and their message, but rather
listening to them attentively, and making plans to prevent dangerous
interference with the climate system.
I am very interested to hear more today about how climate change is
going to affect all of us, what the Administration and others think we
can do to prevent the worst impacts, and what we must do to prepare for
the impacts that are already unavoidable.
Response to Written Questions Submitted by Hon. Daniel K. Inouye to
Steven A. Murawski, Ph.D.
Question 1. There is a general scientific agreement that sea level
rise is occurring at a global average rate of two millimeters per year.
Sea level rise is projected to accelerate during the 21st century, with
the most significant impacts in low-lying regions where subsidence and
erosion problems exist. Rising sea level has worldwide consequences
because of its potential to alter ecosystems and habitat in coastal
regions. Sea level rise and global climate change issues in the coastal
Higher and more frequent flooding of wetlands and adjacent
Increased flooding due to more intense storm surge from
severe coastal storms;
Increased wave energy in the nearshore area;
Upward and land-ward migration of beaches:
Accelerated coastal retreat and erosion;
Saltwater intrusion into coastal--freshwater aquifers;
Damage to coastal infrastructure; and
Broad impacts on the coastal economy.
Dr. Murawski, in your testimony you discuss the effects of sea
level rise on islands and several atolls in the Northwestern Hawaiian
Islands. I am more interested in hearing about the potential impacts of
sea level rise on the inhabited islands of the Pacific region.
Can you tell us about the potential for adverse impacts from sea
level rise on the population centers of the Central and Western
Pacific, particularly with respect to port and road infrastructure,
coastal habitats, living marine resources, and vulnerability of towns
and villages to extreme coastal events, like tsunamis and typhoons?
Answer. NOAA monitors sea level and uses the data to compute
trends. The following table provides estimates of relative mean sea
level trends based on analysis of tide gauge observations. The trends
included in this table are ``relative'' measurements because they
include both the effects of global sea level change and the local
vertical land movement. The accepted range of global sea level rise by
the scientific community is between 2.0 and 3.0 mm/yr.
Station Trend Standard Error *
Johnston Atoll 0.68 mm/yr (0.22 ft/century) 0.31 mm/yr
Midway Islands 0.09 mm/yr (0.03 ft/century) 0.31 mm/yr
Guam 0.10 mm/yr (0.03 ft/century) 0.09 mm/yr
Pago Pago 1.48 mm/yr (0.49 ft/century) 0.56 mm/yr
Kwajalein 1.05 mm/yr (0.34 ft/century) 0.51 mm/yr
Chuuk Atoll 0.68 mm/yr (0.22 ft/century) 0.09 mm/yr
Wake Island 1.89 mm/yr (0.62 ft/century) 0.35 mm/yr
Honolulu 1.50 mm/yr (0.49 ft/century) 0.14 mm/yr
Hilo 3.36 mm/yr (1.10 ft/century) 0.21 mm/yr
Mera, Japan 3.66 mm/yr (1.20 ft/century) 0.12 mm/yr
Aburastubo. Japan 3.33 mm/yr (1.09 ft/century) 0.14 mm/yr
Tonoura. Japan 0.38 mm/yr (0.12 ft/century) 0.12 mm/yr
Wajima, Japan -0.80 mm/yr (-0.26 ft/century) 0.13 mm/yr
Xiaman, China 1.02 mm/yr (0.33 ft/century) 0.30 mm/yr
* The standard errors provide a measure of uncertainty in the computed
Even with the low rates of relative sea level rise tabulated above,
any increase or acceleration in the trends due to climate variability
and change could have significant long-term effects on the remote ocean
islands. This is because portions of many of the islands are low-lying
with relatively flat topographies. Analysis of the tide gauge records
from these islands show no apparent acceleration in the relative sea
level trends to date.
NOAA is working with local coastal managers and stakeholders in the
Pacific, through the Pacific Services Center, to improve the
development and delivery of risk management-related information
products and services in the Pacific. The project is called Pacific
Risk Management `Ohana (family) (PRiMO).
On a larger scale, NOAA is working with other Federal agencies on
the Climate Change Science Program, which is directing a range of
research to address coastal sensitivity to climate change.
Question 2. As you know, we had tragic loss of life in Hawaii due
to a dam failure after a period of torrential rains. Does the National
Oceanic and Atmospheric Administration's (NOAA) research suggest we
will need to pay more attention to mudslides and infrastructure failure
as the oceans warm and rise?
Answer. One need only look at Central America's experience with
Hurricane Mitch in 1998, and California during the 1997-1998 El Nino
event, to see the potential devastation that intense precipitation can
bring to a vulnerable region and its infrastructure. More recently,
loss of life and property due to heavy rains were reported in Hawaii
(February to March 2006) and the northeastern United States (May 2006),
and the early onset of the summer monsoon in India killed 38 people
(June 2006). NOAA research indicates that warmer climates will bring
higher probabilities of extreme precipitation, even in locations where
average precipitation may be decreasing. \1\ NOAA data show increases
in water vapor as the global climate has warmed, consistent with
theoretical expectations. Thus, as the oceans warm and sea level rises
the compounding effects of heavy rainfall and storm surge will need to
be assessed to understand their full impact on coastal infrastructure.
\1\ Karl, T. R., and K. E. Trenberth, 2003. Modern Global Climate
Change. Science, 302: 1719-1723.
Question 3. What is the range of marine ecosystem impacts that we
might expect to see in the Western Pacific, and over what timeframes?
Answer. Sea level rise is compounded by subsidence on islands such
as Maui and Hawaii, which have rates of relative sea level rise of 3.5
to 5 mm/yr. Impacts to marine environments in the Western Pacific could
include changes in water circulation, wave dynamics, sediment
production and resuspension, transport of pollutants and nutrients, and
possibly larval transport. Ecosystem-based management strategies can
help mitigate the effects on reef environments.
Changes to reef processes and reef distribution may occur in areas
most vulnerable to changes in sea level. According to the U.S.
Geological Survey, which has undertaken a study to understand and
predict the response of reefs to accelerated sea-level rise, projected
sea level rise will be particularly significant for low-lying coral
atolls, many of which have maximum elevations of less than 5m above
present sea level. Even in high island settings (e.g., main Hawaiian
islands and Guam), large volumes of sediment stored at or near sea
level could be exhumed and transported to reefs by increases in sea
Coral ecosystems in the Western Pacific are also susceptible to
other ramifications of climate variability and change, including coral
bleaching caused by elevated sea surface temperatures and ocean
acidification caused by increased carbon dioxide concentrations. There
is not a strong consensus on the potential effects of climate
variability and change on other coastal and marine island ecosystems.
such as mangrove and seagrass ecosystems of the Western Pacific.
Accelerating Ocean Acidification
Question 4. A National Oceanic and Atmospheric Administration
(NOAA) study released in April 2006 shows that rising temperatures are
increasing the daily uptake of carbon dioxide by oceans. This changes
the chemistry of seawater, making it more acidic, and having negative
effects on corals and other marine life. NOAA oceanographers confirmed
studies conducted in the 1990s showing that ocean acidification is
occurring at ``significantly increased rates,'' and say ocean chemistry
is changing at least 100 times more rapidly than it has during the
650,000 years preceding our industrial era. At current levels of carbon
dioxide emissions, NOAA computer models predict that oceans will
continue to acidify to ``an extent and at rates that have not occurred
for tens of millions of years.''
Dr. Murawski, the National Oceanic and Atmospheric Administration's
(NOAA) recent study shows that ocean acidification is occurring at
``significantly increased rates,'' adversely affecting water chemistry
and leading to ``major negative impacts'' on corals and other marine
The National Oceanic and Atmospheric Administration (NOAA) has
stated that ocean acidification could substantially alter the
biodiversity and productivity of the oceans. Can you tell us when we
might see the effects of ocean acidification on the biodiversity and
productivity of the ocean in the Pacific islands region?
Answer. While many of the models applied to describe the projected
trends in ocean acidification have centered on the Pacific Ocean, the
models are not specific to the Pacific islands region and uncertainty
remains regarding the precise timing and biological impacts. Recent
estimates indicate roughly half of the anthropogenic CO2
released since the industrial revolution has been absorbed by the
surface waters of the world's oceans. \2\ This has resulted in probably
the most dramatic decrease in ocean pH for the past 400,000 years. \3\
This process of ocean acidification imparts an important control on the
degree to which the surface waters are supersaturated with respect to
carbonate minerals (i.e., saturation state), from which some marine
organisms construct their skeletal structures. Studies on hermatypic
corals, coralline algae, mesocosm coral reef communities and natural
coral reef ecosystems have shown that the calcification of a diverse
selection of organisms and natural systems correlate strongly with
aragonite saturation state.
\2\ Sabine. CI., R.A. Feely, N. Gruber. R.M. Key, K. Lee, J.L.
Bullister, R. Wanninkhof, C.S. Wong, D.W.R. Wallace, B. Tilbrook. F.J.
Millero, T.-H. Peng, A. Kozyr. T. Ono. and A. F. Rios 2004. The oceanic
sink for anthropogenic CO2. Science. 305, 367-371.
\3\ Orr J.C., Fabry V.J. Aumont 0., Bopp L. Doney S. C., Feely R.A.
Gnanadesikan A. Gruber N., Ishida A. Joos F., Key R. M., Lindsay K.,
Maier-Reimer E. Matear R., Monfray P., Mouchet A. Najjar R. G. Plattner
G.-K,. Rodgers K.B. Sabine C.L. Sarmiento J.L. Schlitzer R., Slater
R.D., Totterdell I.J., Weirig M.-F., Yamanaka Y., and Yool A. 2005.
Anthropogenic ocean acidification over the twenty-first century and its
impact on calcifying organisms. Nature. 437(7059), 681.
The aragonite (calcium carbonate) saturation state has already
declined from pre-industrial levels by more than 10 percent in the
tropics and could drop a further 20-30 percent by 2100 if CO2
emissions continue as projected by the Intergovernmental Panel on
Climate Change (IPCC)1S92a ``Business as Usual'' scenario (1995). Model
results based on the more conservative IPCC SRES B2 emissions
atmospheric CO2 increase scenario, together with laboratory
estimates of the sensitivity of corals to ocean acidification, suggest
that the waters of the Pacific islands region will may not support
optimal coral calcification rates beyond approximately 2050
20 years. \4\
\4\ Guinotte J. M., Buddemeier R. W., and Kleypas J. A. 2003.
Future coral reef habitat marginality: temporal and spatial effects of
climate change in the Pacific basin. Coral Reefs, 22(4). 551.
These scenarios are projections of what is likely to occur with
regards to the broad oceanic changes in saturation state. However, the
projections are less likely to accurately predict coastal zone
conditions, where complexities can arise involving buffering by
dissolution of carbonate minerals. Furthermore, the models assume an
equitable biologic response to changes in saturation state while it is
well demonstrated that the magnitude of the effects is not universal
and varies between species and even among individual organisms within
the same species.
We are only beginning to understand how rapid changes in ocean
chemistry will impact marine biota. The magnitude of the effects is not
universal and varies between species and even among individual
organisms within the same species. It is not yet fully understood how
such changes in calcification rate will impact marine ecosystems at the
community scale. For example, it has been suggested that although the
calcification rates of corals are expected to decrease in response to
ocean acidification, organisms such as seagrasses and algae could
benefit from the increased CO2 and thereby hasten the
community shift to a lower biodiversity environment. In addition to
impacts resulting from ocean acidification, marine ecosystems will also
respond to other climate-and human-induced stresses (e.g., increasing
sea surface temperature, rising sea level, overfishing. etc.).
Studies have begun to investigate the synergistic effects of
decreased saturation state and increased temperature on selected coral
species. It is difficult to determine the combined effect these
stressors will have, and the precise timing of any impacts. As a
consequence of our current uncertainty with regards to the anticipated
coastal changes in saturation state, the variability in the biological
response to such changes, and the complexities of other climate change
variables, we cannot be certain of the exact rates, final extent, and
detailed geographic distributions of the impacts of ocean
acidification. The current prevailing scientific view is that such
changes will largely be detrimental to coral communities and that such
changes will likely be experienced within this century.
Question 5. What will be the effects of ocean acidification on the
corals and associated fisheries and tourism businesses that the Pacific
islands are so dependent upon?
Answer. The full range and magnitude of the biological and
biogeochemical effects of ocean acidification are still so uncertain
that a reliable and quantitative estimate of the likely socioeconomic
effects is not yet possible.
Question 6. What future programs or products are planned by NOAA to
monitor the oceans' response to growing carbon dioxide levels and
provide decision-makers with advice on mitigation options, particularly
in the Pacific?
Answer. Ocean acidification is an emerging issue: hence current
understanding does not offer many specific mitigation options at this
time. Efforts have begun to develop observatories at select U.S. coral
reefs that monitor a Reef Metabolic Index (RMI) designed to track broad
changes in community-scale calcification. These observatories will
expand on existing monitoring stations, remote sensing efforts, and
near-reef carbon measurements to measure overall biological performance
of the ecosystem. In addition, efforts have begun using satellite
remote sensing to document the coastal and global long-term
distribution of the phytoplankton Emiliania huxleyi, which is a key
algal species demonstrated to exhibit sensitivity to changes in ocean
pH. This kind of information will be essential for decision-makers to
develop an understanding of the magnitude and extent of the changes
that are occurring within U.S. coral reef ecosystems over time, and for
developing and testing the effectiveness of newly developed mitigation
Response to Written Questions Submitted by Hon. Frank R. Lautenberg to
Steven A. Murawski, Ph.D.
Question 1. In your written testimony you indicate that scientific
uncertainties remain on how much of the observed warming is due to
human activities. Given the complexity of global climate change, that
past observations of the climate are uncertain, and that projections
are being asked looking a century or more into the future, is it
inevitable that there will be uncertainties, no matter how much
research is done?
Answer. The short answer is that yes, there will be uncertainties
no matter how much research is done because the climate system is not a
completely deterministic system. Uncertainty associated with climate
variability and change can have many sources, including the nature and
quality of the available data: the ability of models to capture
processes and their relationships (including predictability); and other
factors related to the impacts of human behaviors \1\ (Moss and
Schneider, 2000). There is also uncertainty about the natural
interactions among the various components of the climate system. Given
the impact uncertainty has on our efforts to understand, communicate,
and adapt to climate change, the scientific community continues to
pursue this area of research and has taken steps in recent years to
address the nature of uncertainty in their assessment efforts, as
reflected in the U.S. Climate Change Science Program (CCSP) and the
Intergovernmental Panel on Climate Change (IPCC) reports.
\1\ Moss. R., and S. Schneider, 2000. Uncertainties, in Guidance
Papers on the Cross Cutting Issues of the Third Assessment Report of
the IPCC, edited by R. Pachauri, T. Taniguchi, and K. Tanaka,
Intergovernmental Panel on Climate Change (IPCC), Geneva.
For example, the CCSP Synthesis and Assessment Product 5.2 is
intended to further develop this topic through the synthesis,
assessment, and communication of what is known about the character and
magnitude of uncertainty, as it applies to climate, and to address some
potential approaches to decision-making given the uncertainty. This
report will address uncertainty related to decision support activities,
ranging from the conduct and communication of research to the actual
consideration and use of scientific knowledge and information products
Research is also leading to improved understanding of natural
climate variability and its impacts. Current global climate models are
improving our understanding of global climate sensitivity, ocean
dynamics, climate feedbacks, and trends in extreme weather events and
enhancing our ability to forecast climate on seasonal time scales and
beyond. As models continue to improve, uncertainties in climate
response will continue to be reduced resulting in a better
understanding of current and future climate projections.
Question 1a. Does NOAA make decisions on many matters governing
resource management (e.g., fisheries management) where there are also
Answer. NOAA develops fishery management plans (FMPs) and
amendments, under authority of the Magnuson-Stevens Fishery
Conservation and Management Act, based upon the best scientific
information available (Section 301(a)(2)). Where there are significant
uncertainties, NOAA supports using a precautionary approach.
Question 1b. What metric is being used to document how much
uncertainty exists and the progress being made to reduce uncertainties?
Answer. NOAA is tracking research progress in reducing uncertainty
through two performance measures under the Government Performance
Results Act (GPRA):
1. Reduce the Uncertainty in Model Simulations of the Influence
of Aerosols on Climate, and
2. Reduce the Uncertainty in the Magnitude of the North
American (NA) Carbon Uptake.
These high-level NOAA Corporate performance measures aim to track
our skill in reducing uncertainty in estimates of North American carbon
uptake from the atmosphere and in model simulations of aerosol impacts
on climate. Improvements in measurements of carbon uptake will be
important in validating carbon trading options at the regional level
(e.g., carbon trading markets being discussed in CA and New England).
The uncertainty of NOAA estimates of North American carbon uptake has
decreased each year since 2003 as the NOAA North American carbon
observation network approaches completion.
Question 1c. What efforts are underway that relate one uncertainty
to another and that amalgamate individual uncertainties into an overall
uncertainty, determining whether an individual uncertainty is important
Answer. The overall uncertainty in the uptake of carbon by the
North American continent is a suitable high-level measure that
represents considerable effort to identify and attribute regional
sources and sinks of carbon dioxide and other related gases. Several
lower-level, more specifically focused measures are used to guide our
efforts. Work is currently underway to employ both vertical
observations from the network and analysis modeling to generate maps of
regional emissions of carbon gases. The early maps, based upon the
network at this time, are promising. They suggest a very real
opportunity to provide, within a few years, emission and uptake maps on
spatial and temporal scales that are useful for making regional
decisions on managing carbon. As regional sources and sinks are
identified and quantified, uncertainty decreases considerably. This
effort is a necessary component of the North American Carbon Program,
which involves a host of universities and many U.S. agencies, including
NOAA, the National Aeronautics and Space Administration, Department of
Energy (DOE), U.S. Department of Agriculture, U.S. Geological Survey,
and the Environmental Protection Agency, among others. The goal is to
build a system that can measure the transfer of carbon between land and
atmosphere across the continent to vastly improve our understanding of
its cycling. Subsequently, the U.S. Climate Change Science Program
(CCSP) embraced this effort and a good part of its coordination is now
conducted through the Carbon Cycle Interagency Working Group of the
CCSP, of which NOAA is a major player. The idea was that measurements
of ecosystem emissions or uptake (done or overseen by other agencies)
should be verifiable with a vertical network of atmospheric
observations (provided by NOAA and its partners) combined with coupled
models that accounted for transport, fires, human emissions, and ocean
influences. The greater understanding that comes with this effort will
allow attribution of sources, lending considerable support to
management and mitigation options for society.
A second benefit of NOAA's carbon effort is the potential use of
satellites to detect carbon emissions and uptake. Today, satellites are
incapable of measuring CO2, with the accuracy and precision
needed for such a study. However, that does not belie their potential
use in the future, and their ability to provide high-frequency spatial
coverage is unsurpassed. Because satellites measure total column
amounts, success of satellite measurements requires a ground-based
vertical network to support them. Satellites also require the
calibrations of the ground based network, as sensors tend to drift,
given that they operate in an inhospitable environment.
A third area where we are focused on reducing uncertainty is
through our work to improve understanding of the growth, distribution,
and chemistry of aerosols in the atmosphere. Unlike carbon dioxide or
other long-lived greenhouse gases, uncertainty in estimating the
contribution of aerosols to global warming is significant. Current
information suggests that aerosols have predominantly a cooling effect,
and the effect could be large. Because aerosols are not well-mixed in
the atmosphere, their effect on cooling or heating depends upon their
distribution, size, and chemical composition. NOAA and its partners
(DOE, University of Colorado, and others) currently are developing an
observational record of aerosols at key locations around the world. We
also are studying aerosol and related processes in the field and
laboratory to improve our understanding of their effect on climate. By
using these findings to improve aerosol-climate models, we
systematically reduce the uncertainty in our estimate of their overall
contribution to climate.
Work is also progressing on the development of an index that
separates uncertainties in climate projections into three components:
(1) sub-seasonal: (2) seasonal; and (3) decadal. Once completed, this
index will allow us to assess the uncertainties in climate projections
for time scales ranging from days to decades.
Question 2. What studies is NOAA undertaking to determine how
available information on climate change is being and can be used, and
what the role is of uncertainties in decision-making?
Answer. The Regional Decision Support (RDS) program of NOAA's
agency-wide Climate Mission Goal includes a focused research capability
designed to address the role of climate and climate information in
decision-making processes for climate-sensitive regions and sectors.
The RDS effort harnesses the intellectual capabilities of NOAA and the
external scientific community through a competitive grants process, and
is conducted in partnership with NOAA's operational and transition
activities to ensure that NOAA's climate services are well oriented to
the needs and capabilities of the constituencies it serves. The RDS
research effort is composed of two programs that address the use of
climate information in decision-making: the Regional Integrated
Sciences and Assessments (RISA) Program. and the Sectoral Applications
Research Program (SARP). These programs complement and enhance each
other, approaching the critical research issue of climate information
for decision support from a regional and sectoral perspective. NOAA has
more than a 10-year investment in research on the impacts and potential
research applications associated with climate variability and change.
This research has mostly been focused on shorter time scales (seasonal
to interannual), but has provided useful insight into society's demand
for and the potential value of climate information over multiple time
scales, from intraseasonal (weeks/months) through decadal.
In addition to the RDS research effort, NOAA is leading the
development and production of two Climate Change Science Program (CCSP)
Synthesis and Assessment Products (SAPs) that address the use of
climate information and the role of uncertainty in decision-making:
a) CCSP SAP 5.2: Best practice approaches for characterizing,
communicating, and incorporating scientific uncertainty in
b) CCSP SAP 5.3: Decision support experiments and evaluations
using seasonal to interannual forecasts and observational data.
NOAA supports similar work internationally by funding the
International Research Institute for Climate Prediction, whose mission
is to enhance society's capability to understand. anticipate, and
manage the impacts of seasonal climate fluctuations in order to improve
human welfare and the environment, especially in developing countries
in Asia, Africa, and the Americas.
Question 2a. If any studies of this nature have been completed by
NOAA, what were the findings?
Answer. Studies conducted by the NOAA RDS effort have addressed the
use of climate information in a suite of diverse regions and sectors,
including the following:
Sectors U.S. Regions
Natural hazard preparedness Pacific Islands
Agriculture and food security Pacific Northwest
Water resource management California
Coastal management Southwest
Public health Southeast (two regions)
Urban New England
Ecosystem management Intermountain West
There are certain sectors where NOAA has been more active, and thus
has more knowledge of the role of climate and climate information,
including the nature and implications of uncertainty. Examples of such
sectors include fire management, public health, water management, and
natural hazards preparedness. Other sectors, such as coastal, urban,
and conservation, are beginning to articulate their interest in
climate. Two sector-specific examples of NOAA's work follow:
Climate information is being used to predict pre-season fire
potential for the United States. NOAA-funded climate
researchers, USDA-Forest Service, and the National Interagency
Coordination Center have developed a series of National
Seasonal Assessment Workshops to enhance fire preparedness,
prescribed fire management, and awareness of the connections
between climate and fire. Participants synthesize and analyze
climate, forestry, and fire science information to predict fire
potential for the upcoming fire seasons.
Climate information is being used to a limited extent by
municipal water managers. Through an ongoing NOAA-supported
study, we have found that municipal planners use a diverse set
of climate information, including climate/water indices, and
some use paleo data to inform thinking about long-term climate.
Some municipal water providers create their own system-specific
indices to determine what might trigger water supply and demand
issues for their water system.
Specific findings of the RDS studies can be found on the websites
for the RISA and SARP activities: http://www.climate.noaa.gov/cpo_pa/
risa/ and http://www.climate.noaa.gov/cpo_pa/sarp/. Although the
findings of NOAA's research vary depending on the characteristics of
the decision-making challenge at hand, this body of work underscores
the potential value of climate information for decision-making, and the
demand for climate information.
In addition. there are some overarching lessons that have been
generated regarding the relationship between humans and climate, and
the characteristics of effective decision support efforts that take
uncertainty into account. Examples include the following:
Climate forecasts are often just one tool utilized by
decisionmakers in addressing a resource management challenge.
Climate forecasts are not deterministic; the utilization of
climate information by decision-makers requires a synthesis of
science, practical resource management strategies and an
anticipation of the requirements for the health and welfare of
human society and the environment.
Effective climate decision support systems include sustained
processes for interaction and collaboration between the
producers and users of climate information. Users include
decision-makers such as farmers, water managers, public health
and safety managers and others responsible for managing
Climate information often requires specific tailoring before
it can be utilized by users. For example. climate-based
forecasts of total water volume might be useful for one type of
water resource decision, but another type of decision might
require information about the onset of seasonal precipitation.
Communication methods must take into account the various
levels of uncertainty associated with both the climate
information and the context within which decisions are being
made (i.e., markets, culture, other environmental stressors).
Question 2b. How does NOAA plan to build on these efforts to assist
the public and government decisionmakers?
Answer. The NOAA Climate Goal and its component programs are
dedicated to providing the Nation with climate services through an
``end-to-end'' process (observations, analysis, prediction,
application, delivery), and over all time scales. The NOAA Climate
Program Office improves climate services through its five components:
The Climate Observations and Analysis (COA) Program--The COA
program's goal is to describe and understand the state of the
climate system through integrated observations, analysis, and
The Climate Forcing (CF) Program--The CF program's goal is
to reduce uncertainty in the information on atmospheric
composition and feedbacks that contribute to changes in Earth's
The Climate Predictions and Projections (CPP) Program--CPP
program's goals are to provide (1) climate forecasts for
multiple time scales to enable regional and national managers
to better plan for the impacts of climate variability, and (2)
climate assessments and projections to support policy decisions
with objective and accurate climate change information.
The Climate and Ecosystems (C&E) Program--C&E program's goal
is to understand and predict the consequences of climate
variability and change on marine ecosystems.
The Regional Decision Support (RDS) Program--RDS program's
goal is to build effective bridges between users and producers
of climate information so that public and private sector
decision-makers have access to and participate in the creation
of new knowledge, processes, tools, and products to improve
risk management, response, and mitigation in sectors sensitive
to climate variability and change.
The National Integrated Drought Information System (NIDIS) is an
example of an end-to-end process covering multiple time scale and
climate program components. The vision for NIDIS is a dynamic and
accessible drought information system that provides users with the
ability to determine the potential impacts of drought and the
associated risks they bring, and the decision support tools needed to
better prepare for and mitigate the effects of drought. Implementation
of NIDIS will require:
Building a national drought monitoring and forecasting
Creating a drought early warning system;
Providing an interactive drought information delivery system
for products and services, including an Internet portal and
standardized products (databases, forecasts, Geographic
Information Systems (GIS), maps, etc.); and
Designing mechanisms for improved interaction with the
public (education materials, forums. etc.).
Question 3. In your written testimony, on page 3, you list various
types of assessment efforts that NOAA has been involved in. You do not
mention that NOAA played an important role in the various sectoral,
regional, and national components of the U.S. National Assessment,
including leading the assessment of the likely impacts on coastal areas
and marine resources and sponsoring several regional studies. Can you
explain why the important results that emerged from these studies were
not discussed in your testimony?
Answer. The work from the U.S. National Assessment report on coasts
and marine resources is mentioned and cited in the testimony. For
example, on page 4 of the testimony the summary article by Scavia et
al. (2002) is referenced. Several studies cited in the U.S. National
Assessment report (e.g., Tynan and DeMaster, 1997; Brown, 1997) are
also cited in the testimony. The U.S. National Assessment report on
coasts and marine resources was published in 2000. The science on this
topic is rapidly evolving. The testimony provides a synopsis of
important recent findings, especially over the 6 years since the 2000
report was published on such topics as ocean acidification, which had
not been well-studied at the time of the U.S. National Assessment.
Question 4. The regional, sectoral, and national results of the
National Assessment formed the basis for the chapter on impacts and
adaptation in the U.S. Climate Action Report 2002 that was endorsed by
all agencies before being submitted to the U.N. Framework Convention on
Climate Change as the official government position. Have any recent
scientific developments caused NOAA to reevaluate its positions
regarding the potential consequences of climate variability and change,
both based on the national level and for the regional and sectoral
efforts that it led and/or sponsored?
Answer. Recent research results from prominent Earth system
scientists are garnering considerable attention, particularly in the
area of sea level rise, and potential trends in extreme events such as
hurricanes, floods, and drought. These results warrant further
attention, investigation, and dialogue across the Federal agencies and
in partnership with Congress. For example, the experience over the past
several years throughout the U.S. West with severe sustained drought
has raised a broad range of issues ranging from drought management to
assessing long-term drought trends, which have important implications
for fire and water management, and ecosystem sustainability. NOAA is
responding in the context of the development and cross-agency
implementation of the National Integrated Drought Information System
(MIDIS). We expect there will be more such calls for a range of climate
information services responsive to the needs of local, state, and
Question 5. In your written testimony, you indicate on page 5 that
``Remarkably only a few documented extinctions occurred in terrestrial
and marine ecosystems during the ice age cycles . . . .'' You indicate
that one reason for this was likely that, overall, the climatic changes
were ``slow compared to the changes in the current millennium.''
Given that the human influence has been primarily during the latter
20th century rather than over the entire millennium, would it be fair
to say that changes during the last glacial period were very slow
compared to the changes over the past 50 years, and that the rate of
change might well be so fast that assurances that species survived
glacial cycling likely provide no assurance that there will be
remarkably few extinctions as a result of human-induced warming?
Answer. Yes, it would be fair to say that survival of many species
during glacial cycling likely provides no assurance that there will be
few extinctions as a result of human-induced warming. Two aspects of
human-induced warming might cause species to become extinct in the
future. One is the rapid rate of human-induced warming, roughly ten
times faster than the rate observed in the paleoclimate record (the
average Earth temperature warmed 4+C in a few thousand years at the end
of the last Ice Age.\2\ compared to the warming of 0.7+C in the past
100 years.\3\, \4\ The second aspect is that climate is
expected to reach conditions outside the range (of temperature,
precipitation, ocean pH, and ocean and atmosphere circulation)
experienced during the glacial cycles.\5\, \6\ Unlike
glacial times, future changes will occur in a world with 6 billion
people within ecosystems now fragmented by human land use.
\2\ Imbrie, J.I., E.A. Boyle, S.C. Clemens, A. Duffy, W.R. Howard,
G. Kukla, et al. 1992. On the structure and origin of major glaciation
cycles: 1. Linear responses to Milankovitch forcing. Paleoceanography.
\3\ Jones, P.D., T.J. Osborn, K.R. Briffa, C.K. Folland, E.B.
Horton, L.V. Alexander, et al. 2001. Adjusting for sampling density in
grid box land and ocean surface temperature time series. Journal of
Geophysical Research. 106: 3371-3380.
\4\ Parker, D.E., C.K. Folland and M. Jackson 1995. Marine surface
temperature observed variations and data requirements. Climatic Change,
\5\ COHMAP Project Members 1988. Climate changes of the last 18,000
years: Observations and model simulations. Science, 241: 1043-1052.
\6\ Houghton, J.T. et al. 2001. Climate Change 2001: The Scientific
Basis, Cambridge University Press.
Question 6. A recent paper appearing in Nature (Grottoli et al.)
indicates that a species of coral has been found that seems to be able
to adapt to higher temperatures. In your testimony, you indicated that
both the temperature increase and ocean acidification are threats to
the coral. Is this newly identified species of coral also able to
survive the ocean acidification that will be caused by the higher
Answer. Grottoli et al. \7\ found that one of the corals they
studied, the branching coral Montipora capitata, was able to switch to
feeding on zooplankton for its predominant food source. This allows it
to better survive a bleaching event, but does not change its tendency
to bleach. A recent study \8\ on the impacts of elevated carbon dioxide
on coral photosynthesis and calcification included M. capitata as part
of the coral assemblage investigated. Although M. capitata appears to
survive bleaching better relative to other corals \7\ it is not immune
from the effects of ocean acidification. Rather, M. capitata was found
to exhibit a pronounced reduction in calcification rate in response to
elevated carbon dioxide.
\7\ Grottoli, A.G., L.J. Rodrigues, and J.E. Palardy. 2006.
Heterotrophic plasticity and resilience in bleached corals. Nature.
\8\ Langdon, C., and M.J. Atkinson. 2005. Effect of elevated
pCO2 on photosynthesis and calcification of corals and
interactions with seasonal change in temperature/irradiance and
nutrient enrichment. Journal of Geophysical Research--Oceans. 110(C9):
Question 7. In your written testimony you indicate that, apparently
associated with an increase in air temperatures, ``the density of krill
. . . has decreased by more than 90 percent in the region since 1976''
and that this is having associated impacts on other species. Is this
evidence of a dangerous anthropogenic interference with one of nature's
Answer. The reasons for the decline in krill populations in
Antarctica are not clear and cannot be explained fully. Many factors
are believed to have contributed to the declines. We know that the
Southern Ocean is undergoing a warming trend, which likely influences
ocean circulation and sea-ice dynamics. Although these factors likely
affect krill populations, the definitive link between climate change
and anthropogenic interference has not been established. Due to its
relative isolation, the direct anthropogenic effects in Antarctica are
substantially less than in other parts of the world. It also is clear
that the decline in krill populations is not directly related to
overfishing. The present annual harvests in Antarctica are around
100,000 tonnes, while the International Commission for the Conservation
of Antarctic Marine Living Resources precautionary catch limits are
more than 4 million tonnes. The catch limits are based on relatively
recent surveys. There is considerable debate in the scientific
community concerning the role indirect effects may have played in this
ecosystem. As my testimony indicated, reduced sea ice is generally
believed to have played a major role in reduced krill populations.
Other causal effects are difficult to quantify. Evidence suggesting
anthropogenic interference with the Antarctic ecosystem is not clear
and considerable debate exists among scientists. We are addressing
these concerns, but it will be some time before cause and effect is
Question 7a. If not at 90 percent, at what point would it be that
NOAA management would strongly advocate publicly and with the
Administration for actions to slow and limit further changes in the
Answer. NOAA will continue to carry out our mission to ``understand
and describe climate variability and change to enhance society's
ability to plan and respond'' through our research, observations, and
modeling capabilities, but we do not focus on advocacy. As a key part
of the U.S. Climate Change Science Program, we are working on
developing synthesis and assessment products intended to provide the
best possible scientific information, developed by a diverse group of
climate experts, for the decision community. These reports are designed
to address a full range of scientific questions and evaluate options
for responses that are of greatest relevance to planners and decision-
Response to Written Questions Submitted by Hon Frank R. Lautenberg to
Dr. Syun-Ichi Akasofu
I am glad to have this opportunity to express my thoughts on the
global warming issues in more detail, since it was not easy to do so
during the testimony due to the time constraints. I have tried to
answer all your questions.
If you have further questions, please do not hesitate to contact
me. Also, I am more than happy to explain more when I come to
Washington, D.C., next time.
Question 1. Regarding Figure 1 in your written testimony--Why is it
that the graph indicating sources of energy ends at 1985 and does not
show the associated increase of energy use with temperature up to the
Answer. I received the invitation to testify while I was in Tokyo
and had only a few days to prepare the written document by working with
my staff in Fairbanks, Alaska, via phone and fax. The original Figure 1
in my testimony was prepared under these difficult circumstances.
Question 1a. Could you please provide an updated plot that extends
the energy record to at least the year 2000, or preferably extends both
the emissions and temperature records to 2005?
Answer. I am glad to have an opportunity now to provide you with an
updated version of Figure 1, which is now Figure A in this
correspondence. I also prepared a new one with the CO2 data
alone (Figure B), which I wanted to use to begin with. Please notice
that the range of temperature changes is much greater in the Arctic
than the global average provided by the IPCC Reports.
Question 2. In Figure 1, is the mid-20th century jump (i.e.,
increase and then decrease) in the Arctic temperature record that you
show a usual occurrence; that is, is there any indication that such
sudden and short duration warming periods have occurred previously?
Answer. Before 1850 or so, there were not many thermometers in the
whole world. Therefore, we have to rely on proxy data. Unfortunately, a
1000-year temperature record based on the tree ring analysis by Mann
(the so-called `hockey stick') used most frequently and prominently in
IPCC Reports and others, is now very controversial; please see your
The most reliable data for the past are deduced from ice cores
(O18). We are fortunate to have such a high-resolution (in time) data
from Severnaya Zemlya (Figure 5 in my testimony, which is reproduced
here as Figure C). There have been a number of fluctuations, large and
small, superposed on a linear increase (which is discussed in
conjunction with your Item 8).
Please note that the top, middle, and bottom traces agree
reasonably well, confirming the accuracy of all the data shown.
Question 3. Might there be problems with the data set that is used
to generate this record, especially given the limited time over which
observations are available in the Arctic? Could you supply some
indication of the number of measurements going into the Arctic record
and the percentage coverage of the Arctic that is represented over time
by this record?
Could it be that only one part of the Arctic was as warm in the mid
20th century as it is currently and other parts that did not warm were
not represented in the temperature record of Polyakov?
Answer. The top of Figure D shows the same temperature record as
that of Figure A (or Figure 1 of my testimony). Please note that added
to it, as an insert, is the distribution of the stations from which
data was used. They are distributed mostly along the entire arctic
coast. (Russia actually kept excellent temperature records even in
Siberia and recorded carefully watched changes in natural phenomena,
better than some other places in the world.)
The bottom of Figure D shows sea water temperature data. They are
taken from the middle of the Arctic Ocean as the insert shows.
Please note that the temperature record similar to figure A is
shown on page 23 of the ACIA Report ``Impact of a Warming Arctic''
(Figure 4 of my testimony); it includes continental data in the Arctic.
It shows a larger increase after 1970 than in 1940, because a very
prominent warming occurred in the continental Arctic, which is
disappearing during the last decade or so, as shown in Figure 3 of my
Question 4. With the Arctic indicated to be as warm in the mid-20th
century as at present, and with that warming lasting for a time
comparable to the time of the current warming, is there evidence that
indicates that the same types of changes in sea ice, permafrost,
glacial melting, species shifts, etc. occurred as we are seeing at
present? Do the Indigenous elders recall such warm periods and the
appearance of the new birds and other species that are now occurring in
Answer. Sea ice: The only reliable, long-term data before 1950 are
observations of the southern ice edge in the Norwegian Sea (Figure E;
my testimony Figure 7b). Please note that the range of changes during
1920-1960 (corresponding to what you term `the mid-20th century jump'
was much larger than the present change after 1970; the present change
is much smaller than that during the mid-20th century in the Norwegian
Sea. Please note also a linear change similar to the ice core change
that will be discussed in your Item 8.
Permafrost: Figure F shows the best available temperature data on
permafrost, from both Siberia and Fairbanks. Please note that the
temperature was decreasing until 1970, in spite of the fact that the
amount of CO2 began to increase rapidly in about 1940.
Permafrost temperature closely follows air temperature (please compare
Figure F with Figure A).
Glaciers: Old Russian records show that many Alaskan glaciers have
been receding since 1800 or earlier (Figure 7a in my testimony). The
recession did not start in 1970; please see also Figure G. Changes in
the European Alps are similar to it.
Many recent TV programs show large blocks of ice falling off the
glacier terminus, implying that this phenomenon is a manifestation of
global warming. Most people do not realize that glaciers are actually
``rivers of ice'' (where ice flows) and that ice has been falling off
glacier termini for thousands and thousands of years.
Others: Some species are obviously quite sensitive to temperature
changes; fish are quite sensitive to sea water temperature changes. I
am not an expert on such issues, but happen to have an interesting
figure (Figure H), which shows changes of fish populations in the
Pacific. It seems that such changes are a common occurrence.
Question 5. In your written testimony you state that ``It is also
important to note that both the Arctic and global temperatures began to
decrease in about 1940, when our release of greenhouse gases began to
increase rapidly. Thus the increase-decrease between 1920 and 1970 must
be natural change.'' The most often mentioned natural factors that
could be responsible for a warming are a reduction in the amount of
volcanic aerosol and an increase in solar radiation. If these factors
are indeed responsible for this warming, it would seem to lead to the
conclusion that the Arctic climate is very, very sensitive to slight
changes in the amount of energy driving the climate system, in that the
volcanic and solar influences, in terms of Watts per square meter, have
been relatively small. Thus, should not your assertion that these
changes are natural make us very, very concerned about the climatic
changes that lie ahead given the large changes in atmospheric radiation
being caused by the continuing human-induced increases in the
concentrations of greenhouse gases?
Question 6. The detection and attribution studies reported on by
the IPCC conclude that the warming prior to about 1940 was likely due
partly to natural factors and partly to the release of greenhouse
gases, and that the subsequent cooling was due mainly to the increasing
emissions of SO2 and possibly a slight diminution in solar
radiation and return of volcanic eruptions. These carefully done
detection and attribution studies, endorsed by the IPCC, make clear
that such analyses must include consideration of all forcing factors
(and that there are natural and human-induced factors that induce
warming and other factors that can induce cooling). It therefore seems
to be quite a jump to suggest that the mid-century part of the record
must be entirely due to natural factors without considering the human
influences also likely to have exerted influences throughout the 20th
century. What steps does your analysis take to conclude that the full
set of human-induced factors is not having an influence?
Answer to Questions 5 and 6. I believe that all the IPCC GCMs
consider effects of observed volcano effects (past major eruptions),
solar output changes, aerosol effects (SO2), etc., and their
positive/negative feedback effects as well, quantitatively with the
best knowledge available. However, they cannot reproduce the mid-20th
century jump. It is very hard to explain the 1940-1970 decrease,
particularly since CO2 began to increase rapidly at that
time; the initial increase is also hard to explain. Therefore, at this
stage, I must come to the same conclusion I did earlier during my oral
testimony, as I describe below again.
We always come up with interesting ideas about how to explain
natural phenomena, but if they fail the quantitative tests, we have to
abandon them. This happens every day in science. If the idea has failed
the test and knowing that the test was conducted with the best
knowledge available at the time, scientists should not pretend or claim
that their interesting ideas are still alive. Such interesting but
unproven ideas belong to science fiction. During my testimony I showed
that the continental arctic warming during 1970-2000 belongs to that
category (Figure 2 of my testimony), too. Nothing is 100 percent
certain in climatology, but I believe that the Senate subcommittee
members did not want `noncommittal' statements from the panel members.
On the other hand, if the idea passes the test, I am happy to support
the idea. Since I am not a climatologist, I have no hang-up in either
camp. What I can say as an auroral physicist is that the present
climatology is very abnormal.
As you may know, the ``mid-20th century jump'' is a northern
hemisphere phenomenon, not a southern hemisphere phenomenon. Thus, it
is NOT A GLOBAL phenomenon. This is very clear in the paper by Jones,
which became the basis of the IPCC Report. In fact, it appears to be a
phenomenon above 40+ latitude in the northern hemisphere, so that it is
doubtful that it is really a global phenomenon. It may well be that
this is why the GCMs cannot reproduce it as the greenhouse effect!
(Just as is the case of the continental arctic warming!)
Some people argue that the GCMs have not advanced enough to be used
for such tests. If so, they would logically also have to doubt the
basis of the Kyoto protocol on global warming. There may be some
problems with prediction, because we have to assume the amount of
CO2 released in the future. On the other hand, we are using
GCMs for what we call ``hind-casting'' based on the observed CO2
data, and the GCMs are accurate enough for our purpose; furthermore, we
are using 14 GCMs.
Question 7. You indicate on page 1 of your written testimony that
``It is incorrect to conclude that the present warming in the Arctic is
due entirely to the greenhouse effect caused by man.'' In answer to a
question, you indicated that such assertions were being made mainly by
the media and did not indicate any scientific assessments that were
making this assertion. Is it your opinion, therefore, that we can rely
on the IPCC and ACIA assessments, even though there may be some
misimpressions given by some in the media, or are you suggesting that
the assessments are also flawed?
Question 7a. If the latter, please provide specific examples where
you think the complete picture is not being presented. What part of the
warming do you judge to be human-induced and what fraction natural, and
what is your estimate of how this ratio has changed over time?
Answers to Questions 7 and 7a. Both the IPCC and ACIA Reports
served in raising awareness of the CO2 problem. However, I
am not very happy about the ``tactics'' they used (you must have heard
about some of the complaints from the contributors). There was no
``refereeing'' like scientific papers for scientific journals. During
our testimony, Dr. Reiter was quite critical of one chapter on malaria,
saying that the contents was very poor. You will recall that this was
also a major complaint by Dr. Michael Crichton during his testimony in
one of the earlier hearings. As I also mentioned in my testimony, the
present climate research presented by the IPCC Report is not taking the
normal scientific practice. For example, Mann's ``hockey stick'' figure
was so appealing for the purpose of raising awareness of the greenhouse
effect, it was prominently used by the IPCC Reports. Mann's figure
shows neither the Medieval warming nor the Little Ice Age, so that some
scientists questioned its accuracy. Finally, two Canadian experts in
statistics analyzed the same data (which they said Mann was very
reluctant to make available; as you may know, Congress finally demanded
he submit the data) and showed that there is no ``hockey stick'' in the
data (Figure I). I am afraid that Mann's results, the IPCC
``flagship,'' may turn out to be a flawed case. Dr. Robert Correll used
it in his testimony without telling us that there is some problem with
it, even if he believes its accuracy. It is unfortunate that it gave
the impression that the greenhouse effect did indeed take off.
In science, new results should be scrutinized by the community, and
if they survive the scrutiny, they become scientific facts. It is my
belief that the IPCC way of mobilizing hundreds of scientists is not a
good practice in science. I wonder how many of the IPCC contributors
can defend Mann's work, in spite of the fact that they are the co-
Another important issue: as I testified, many climatologists use
satellite data, which became available only in the 1970s, when the
latest rise in temperature occurred. Therefore, what they report is
naturally related to the temperature rise. Many of the presently active
scientists were born in the 1960s and 1970s, so that it is natural for
them to assume that the temperature rise has been happening during
their whole life. However, in terms of genuine climatology, it is but
an instant. That is why I want to call them ``instant climatologists'';
many of them do not want to work on the mid-20th century jump, since it
will take a great deal of effort to get data similar to what satellites
can provide readily. In order to work on climatology, I am asking my
colleagues that they should try to get at the very least data that
spans a few hundreds years. Climatology used to be like anthropology.
However, after the advent of satellites and computers, it has become an
Now, the present problem is that the media and many special
interest groups take the scientific data after the 1970s as scientific
fact for the greenhouse effect. As soon as results associated with the
rising temperature are reported in scientific papers (or even before),
they are immediately reported by them as scientific facts proving the
greenhouse effect, confusing the term global warming as synonymous with
the greenhouse effect. Many media people do not have enough scientific
background on the greenhouse effect. I might add that scientists who
doubt or criticize greenhouse studies are demonized by the media these
days. All this is a very abnormal circumstance in science, I am afraid.
Whenever an issue is raised, the media defends itself by saying that
hundreds of scientists joined in the preparation of the IPCC Reports. I
hope you can understand the problem.
Distinguishing between natural and manmade components of climate
change is a very difficult task, but IARC scientists are challenging
the problem, since this is the one way to ``reduce uncertainty in
climate change predictions''; please see your item 8.
Question 8. In your Figure 7b (top) you include a linear trend line
beginning in 1760 and going to the year 2000. Why do you assume that
human-induced influences should be linear, especially given the
temporal and spatial variations in the forcing terms, interactions
these might have for the atmospheric and oceanic circulations, etc.?
Answer. The linear line in Figure C is NOT meant to be human-
induced influence at all. It is only recently that the ice core (O18)
analysis provided us with proxy data for the last 200 years. The longer
the analysis period is, the more accurate the baseline becomes, on
which various fluctuations are superposed. In the 100-year data (Figure
A), we could not see clearly the linear trend (the ACIA Report, p. 23,
used the 100-year average value as the baseline). There is little doubt
about the presence of the linear trend in the 200-year data.
As you correctly observed, there is no way to explain the linear
trend by the greenhouse effect. I speculate that it is a natural
change; the sea ice data and some other O18 data show similar linear
trends. Are we still recovering from the Little Ice Age?
IPCC Reports say that the global temperature increased by 0.6+C
during the last century, and it implies that the increase is caused by
the greenhouse effect. If the linear change continued until recently,
and if it were indeed to be natural change, the greenhouse effect will
not be a large fraction of the 0.6+C. This is the uncertainty we have
to face in climate change research at the present time. We have to
isolate the linear trend and other natural changes in detail and find
out the real contribution of the greenhouse effect.
Question 8a. Might it be that conditions continue in one state for
a while and then flip, for example, once the ice melt reaches a certain
amount or once temperatures in key regions exceed the freezing point?
Answer. What you are referring to may be what we call the
``threshold'' point. For example, many researchers told me earlier that
sea ice in the Arctic Ocean off the Alaskan coast had crossed ``the
point of no-return'' during the summer months based on satellite data.
However, sea ice was much closer to the Alaskan coast in 2005 than in
2004 or 2003. It came back last year.
In principle, what you say may occur; however, I am not sure if the
present climatology can predict accurately the threshold point of any
climate change phenomena.
Question 9. Although climate models may not provide sufficiently
accurate representations of the spatial distribution of warming, do you
agree that they do include representations of the overall thermodynamic
and dynamic influences, so that the global integral of the influence,
which is presumably based on the overall balance of energy, of
increasing concentrations of greenhouse gases, and of other factors is
roughly correct? What improvements do you think are most needed in the
available climate models?
Answer. The physics of the greenhouse effect is sound and clear;
that is not the question. The questions are: (1) how much did the
greenhouse effect contribute to the 0.6+C increase and the mid-20th
century jump, and (2) how much will the temperature increase by 2100,
more than 6+C or less than 1+C? (When I say this, some scientists
immediately argue with me and say that I deny the greenhouse effect.
They forget the normal scientific practice, and the IPCC must have
created such an unscientific atmosphere.)
At the International Arctic Research Center (IARC), our main
objective is to ``reduce uncertainty in future climate change
predictions.'' Certainly, our progress in science will improve the
modeling effort. On the other hand, we should not forget that the
Earth's temperature fluctuates all the time. We cannot understand the
cause(s) of the Big Ice Age, the Medieval warming (1000-1300 AD, almost
as warm as the present time), and the Little Ice Age (1400-1900?), in
addition to the fact that the temperature was higher at the beginning
of the present interglacial period and some other interglacial periods
when only anthropoids were present on Earth. This is what Dr. Thomas
was stressing during his testimony. There is no reason to assume that
the linear change suddenly stopped after 1900. We have to identify and
subtract natural change from the on-going changes; the rest will give
us some idea about the greenhouse effect.
I am afraid that this communication is getting too heavy, so that I
have put two cartoons at the end. I find that cartoonists observe well
the present situation.