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81–495CC 2002

THE U.S. NATIONAL CLIMATE CHANGE ASSESSMENT: DO THE CLIMATE MODELS PROJECT

A USEFUL PICTURE OF REGIONAL CLIMATE?

HEARING

BEFORE THE

SUBCOMMITTEE ON 

OVERSIGHT AND INVESTIGATIONS

OF THE

COMMITTEE ON ENERGY AND 

COMMERCE 

HOUSE OF REPRESENTATIVES

ONE HUNDRED SEVENTH CONGRESS

SECOND SESSION

JULY 25, 2002

Serial No. 107–117

Printed for the use of the Committee on Energy and Commerce

(

Available via the World Wide Web: http://www.access.gpo.gov/congress/house

COMMITTEE ON ENERGY AND COMMERCE 

W.J. ‘‘BILLY’’ TAUZIN, Louisiana, Chairman 

MICHAEL BILIRAKIS, Florida 

JOE BARTON, Texas 

FRED UPTON, Michigan 

CLIFF STEARNS, Florida 

PAUL E. GILLMOR, Ohio 

JAMES C. GREENWOOD, Pennsylvania 

CHRISTOPHER COX, California 

NATHAN DEAL, Georgia 

RICHARD BURR, North Carolina 

ED WHITFIELD, Kentucky 

GREG GANSKE, Iowa 

CHARLIE NORWOOD, Georgia 

BARBARA CUBIN, Wyoming 

JOHN SHIMKUS, Illinois 

HEATHER WILSON, New Mexico 

JOHN B. SHADEGG, Arizona 

CHARLES ‘‘CHIP’’ PICKERING, Mississippi 

VITO FOSSELLA, New York 

ROY BLUNT, Missouri 

TOM DAVIS, Virginia 

ED BRYANT, Tennessee 

ROBERT L. EHRLICH, Jr., Maryland 

STEVE BUYER, Indiana 

GEORGE RADANOVICH, California 

CHARLES F. BASS, New Hampshire 

JOSEPH R. PITTS, Pennsylvania 

MARY BONO, California 

GREG WALDEN, Oregon 

LEE TERRY, Nebraska 

ERNIE FLETCHER, Kentucky 

JOHN D. DINGELL, Michigan 

HENRY A. WAXMAN, California 

EDWARD J. MARKEY, Massachusetts 

RALPH M. HALL, Texas 

RICK BOUCHER, Virginia 

EDOLPHUS TOWNS, New York 

FRANK PALLONE, Jr., New Jersey 

SHERROD BROWN, Ohio 

BART GORDON, Tennessee 

PETER DEUTSCH, Florida 

BOBBY L. RUSH, Illinois 

ANNA G. ESHOO, California 

BART STUPAK, Michigan 

ELIOT L. ENGEL, New York 

TOM SAWYER, Ohio 

ALBERT R. WYNN, Maryland 

GENE GREEN, Texas 

KAREN MCCARTHY, Missouri 

TED STRICKLAND, Ohio 

DIANA DEGETTE, Colorado 

THOMAS M. BARRETT, Wisconsin 

BILL LUTHER, Minnesota 

LOIS CAPPS, California 

MICHAEL F. DOYLE, Pennsylvania 

CHRISTOPHER JOHN, Louisiana 

JANE HARMAN, California 

DAVID V. MARVENTANO, Staff Director 

JAMES D. BARNETTE, General Counsel 

REID P.F. STUNTZ, Minority Staff Director and Chief Counsel 

SUBCOMMITTEE ON OVERSIGHT AND INVESTIGATIONS

JAMES C. GREENWOOD, Pennsylvania, Chairman 

MICHAEL BILIRAKIS, Florida 

CLIFF STEARNS, Florida 

PAUL E. GILLMOR, Ohio 

RICHARD BURR, North Carolina 

ED WHITFIELD, Kentucky 

Vice Chairman 

CHARLES F. BASS, New Hampshire 

ERNIE FLETCHER, Kentucky 

W.J. ‘‘BILLY’’ TAUZIN, Louisiana 

(Ex Officio) 

PETER DEUTSCH, Florida 

BART STUPAK, Michigan 

TED STRICKLAND, Ohio 

DIANA DEGETTE, Colorado 

CHRISTOPHER JOHN, Louisiana 

BOBBY L. RUSH, Illinois 

JOHN D. DINGELL, Michigan, 

(Ex Officio) 

(II) 

C O N T E N T S 

Page

Testimony of: 

Janetos, Anthony C., Senior Fellow, The H. John Heinz III Center for 

Science, Economics, and the Environment ................................................. 5 

Karl, Thomas R., Director, National Climatic Data Center .......................... 13

Lashof, Daniel A., Deputy Director, Climate Center, Natural Resources 

Defense Council ............................................................................................. 27

Michaels, Patrick J., Professor and Virginia State Climatologist, Department of Environmental Sciences, University of Virginia .......................... 50

O’Brien, James J., Director, Center for Ocean-Atmospheric Prediction 

Studies, Florida State University ................................................................ 34

Pielke, Roger A., Sr., President-elect, American Association of State Climatologists, Colorado State Climatologist, and Professor, Department 

of Atmospheric Science, Colorado State University ................................... 42

(III) 

(1)

THE U.S. NATIONAL CLIMATE CHANGE ASSESSMENT: DO THE CLIMATE MODELS 

PROJECT A USEFUL PICTURE OF REGIONAL 

CLIMATE? 

THURSDAY, JULY 25, 2002

HOUSE OF REPRESENTATIVES, 

COMMITTEE ON ENERGY AND COMMERCE, 

SUBCOMMITTEE ON OVERSIGHT AND INVESTIGATIONS, 

Washington, DC. 

The subcommittee met, pursuant to notice, at 9:30 a.m., in room 

2322, Rayburn House Office Building, James C. Greenwood (chairman) presiding. 

Members present: Representatives Greenwood, Deutsch, and 

Fletcher. 

Staff present: Peter Spencer, professional staff; Yong Choe, legislative clerk; and Michael L. Goo, minority counsel. 

Mr. GREENWOOD. On the record. Good morning. The meeting will 

come to order, and let me begin by apologizing to our witnesses and 

to our guests for the tardiness. It was actually unavoidable. 

The Chair recognizes himself for 5 minutes for an opening statement. 

Good morning, and welcome. This morning we will stand at the 

intersection of science, policymaking, and public concern about climate change to consider if an influential report provides the guidance necessary to navigate this often confusing and uncertain territory. 

At issue is the use of climate models to create the regional climate change scenarios that frame the discussion in what is called 

in shorthand the U.S. National Assessment on Climate Change. 

The national report about this assessment, prepared by scientists 

and researchers under a Federal advisory committee, known as the 

National Assessment Synthesis Team, two co-chairs of which are 

before us today, seeks to provide policymakers and the public with 

plausible pictures of regional climate 50 to 100 years from now 

under the impact of global warming. 

Now let me note as we head into this a couple of points about 

my perspective. First, I tend to agree with the view expressed in 

some of the testimony we will hear this morning that there are 

some reasonable mitigation—there are some reasonable mitigation 

measures and other policy strategies we can take to address climate change risks, and that these do not depend upon the scientific 

dispute before us. Indeed, this dispute should not be used to avoid 

decisions on such policies. 

2

Of course, there continues to be much debate about some of these 

policy decisions, how much can or should we do, when should we 

do it, and the debate has engaged many members of the Energy 

and Commerce Committee on both sides of the aisle. 

The hearing today, though it will help inform the debate, is not 

the appropriate forum to conduct that debate, which would only 

distract us from the important questions before us this morning. 

Second, this is not to suggest we should glide over questions of 

science and the scientific validity of the tools and methods used to 

drive understanding of inherently science based issues. We need 

sound science to inform our decisions and to ensure our actions in 

the name of science—to ensure that our actions in the name of 

science aren’t misguided because we were more confident than we 

should have been. 

So we begin today with a straightforward question: Do the climate models project a useful picture of regional climate? We have 

asked our panelists today, all scientists and all quite familiar with 

the controversies about climate, climate variability and impacts, 

and the national assessment, to comment on this and to speak to 

the role and suitability of the models used in this report. 

In the U.S. Climate Action Report released to the United Nations 

this past May, reference to the National Assessment discussed the 

use of the models this way. ‘‘Use of these models is not meant to 

imply that they provide accurate predictions of the scientific 

changes in climate that will occur over the next 100 years. Rather, 

the models are considered plausible projections of potential changes 

for the 21st century.’’ Two initial questions come to my mind when I read this, and I 

hope the witnesses can assist us in answering these questions this 

morning. The first has to do with the plausibility of the picture 

painted by the models. This is basically a science question, which 

I am sure the experts here can sort out for this layman, and this 

is how reliable are the predictions of plausible regional outcomes, 

given the admitted limitations of the modeling, and what would 

this mean for the usefulness of the report? And given the wide variation in the projections’ results that oppose each other in one area 

but are similar in others, is it reasonable to rely upon them to take 

specific actions or to adopt specific policies? 

This appears to be a thoughtful report, and I believe the authors 

sincerely attempted to work through describing some of the uncertainty for policymakers and the public. Was it sufficient? How did 

the models work in the full picture here? 

The second question relates to the problem of communicating the 

uncertainty. The reference above makes a rather nuanced description of predictions versus the projections. Yet the New York Times 

which reported the Climate Action Report’s reference to the Assessment wrote this back in May: ‘‘The report says the United States 

will be substantially changed in the next few decades, very likely 

seeing the disruptions of snow-fed water supplies, more stifling 

heat waves, and the permanent disappearance of Rocky Mountain 

meadows and coastal marshes.’’

Was this the message the authors want the public to take away? 

We must come to grips with the fact that a scientific assessment 

such as this is more than an academic exercise read by the few who 

3

can grasp all the complexities. It is a document meant to guide us, 

policymakers and the public, though complicated policy intersections where we really rely on science as much as we can. 

The stakes here are as high as any could be, the very inhabitability of our planet. The cost of reducing the stakes is also high. 

For both of these reasons, the reliability of our predictive models 

must be high indeed. 

I thank the witnesses again, especially those who have traveled 

so far to testify this morning. I now recognize the ranking member, 

Mr. Deutsch of Florida, for his opening statement. 

Mr. DEUTSCH. Thank you, Mr. Chairman. I believe this is our 

third hearing regarding climate change. Just a few comments representing south Florida. At some level I think we are probably 

more affected by potential climate change than anywhere in the 

country, and there won’t be much of south Florida left. 

The sea level of Florida’s Gulf Coast has risen sharply, up as 

many as 8 inches over the last 100 years, and more sharply over 

the last few decades and, as people are well aware, higher sea levels can mean beach erosion, threatening homes and communities, 

coral reef erosion, and more intense and damaging storms and hurricanes. 

Florida’s average temperature since the Sixties has also risen. 

Higher temperatures mean more heat related illnesses, decreasing 

air quality. Both higher sea levels and higher temperatures will seriously affect obviously greater areas, including our Everglades restoration efforts, and can severely affect our tourism industry. Florida is a community where environment and the economy effectively 

are one. 

I look forward to the testimony. I am just somewhat disappointed. As you are well aware, this is our last week in session, 

and we were in session until about two o’clock yesterday evening, 

and I don’t really expect many members to be here this morning, 

which is unfortunate. But I am sure their staffs can review the 

record. I yield back. 

Mr. GREENWOOD. Thank you, ranking member. 

[Additional statements submitted for the record follow:]

PREPARED STATEMENT OF HON. PAUL E. GILLMOR, A REPRESENTATIVE IN CONGRESS

FROM THE STATE OF OHIO

Mr. Chairman, I wanted to quickly add my comments regarding climate change. 

In particular, I appreciate the opportunity to learn about the role of climate models 

as well as to discuss whether the U.S. National Climate Change Assessment should 

continue to serve as a benchmark with regard to potential impacts of climate change 

on our environment and human health. 

I also look forward to hearing from our panel of witnesses. I should also point out 

that in a time when the U.S. economy is so dependent upon energy, and so much 

of our energy is derived from fossil fuels, reducing emissions poses major challenges. 

Like many Members, I feel that rushing to judgement on these matters could be 

very costly, both socially and economically. In an effort to produce sound environmental policy while maintaining steady economic growth, I am hopeful that we will 

continue to review scientific information about climate change to evaluate potential 

economic and strategic impacts of a warmer, and perhaps more variable, climate. 

Again, I thank the Chairman and yield back my time. 

4

PREPARED STATEMENT OF HON. W.J. ‘‘BILLY’’ TAUZIN, CHAIRMAN, COMMITTEE ON

ENERGY AND COMMERCE

Thank you Chairman Greenwood. And, let me also thank you for putting together 

what promises to be an informative hearing—one that gets to the heart of a controversy that has lingered over this national assessment for a couple of years now. 

I can tell you I have a pretty good appreciation, as does everybody from the Bayou 

State, for what Mother Nature can do to us. And she sure does remind us in a variety of ways. 

The U.S. National Assessment also reminds us about the ways our country may 

someday be affected by climate change—whether that climate change is natural or 

influenced by man. But it also conveys some pictures of the future that, as we’ll 

hear this morning, might not be quite what they seem. 

I look forward to learning more about the use of climate models in the assessment. I’m curious to know whether the inherent uncertainties in these models—un- certainties I understand to be widely accepted within the science community—were properly accounted for when using the models to sketch out the climate change scenarios in this report. 

I’m also curious to learn whether, if they weren’t properly accounted for, whether 

they undercut what was otherwise a well-intentioned, and potentially useful report. 

Did the models, in effect, send all this good research focusing on the wrong impacts? 

Nobody has perfect foresight. But we do have scientific assessments and other 

tools to help us reduce the odds that our decisions about the future are more than 

wild guesses. What troubles me, and I believe many Members who must confront 

difficult and potentially expensive decisions about climate change, is that something 

that is asserted to be sound science, is not as sound as it was portrayed to be. This 

creates false assurance where perhaps knowledge of what we don’t know would be 

more useful to guard against risks. It also threatens to undercut public trust in the 

science policymakers use to make their decisions. 

We have before us today a distinguished panel of experts who can explain the role 

of climate modeling in this assessment. They can put matters in proper perspective 

for us. We have them all here on one panel, too, so that perhaps we can generate 

some discussion to get further to the bottom of this controversy. 

I thank you again, Mr. Chairman and yield back the remainder of my time.

Mr. GREENWOOD. It is the case that we were in session until two 

o’clock this morning. It is not an excuse, just an explanation for 

why some of the members may come in a little later than otherwise. 

To the panelists, you are aware that the House—this committee 

is holding an investigative hearing, and I think you have been informed that when we hold investigative hearings, it is our custom 

to take our testimony under oath. Do any of you object to giving 

your testimony under oath? Okay. 

Not normally for this kind of hearing but for other hearings we 

must inform you that you are entitled to have a counsel, have a 

lawyer represent you, be represented by counsel. Do any of you 

wish to be represented by counsel? Okay. In that case, if you would 

all stand and raise your right hand, I will give you the oath. 

[Witnesses sworn.] 

Mr. GREENWOOD. Thank you. You are under oath. Let me introduce the panel. From my left to right, Dr. Anthony C. Janetos, Senior Fellow with the H. John Heinz Center for Science, Economics, 

and the Environment; Dr. Thomas Karl, Director of the National 

Climatic Data Center in North Carolina; Dr. Daniel Lashof, Deputy 

Director of the Climate Center, the Natural Resources Defense 

Counsel; Dr. James J. O’Brien, Director of the Center for OceanAtmospheric Prediction Studies at Florida State University; Dr. 

Roger Pielke, Sr., President-Elect of the American Association of 

State Climatologists, Colorado State Climatologist, and Professor in 

the Department of Atmospheric Science at Colorado State University; and Dr. Patrick J. Michaels, Professor and Virginia State CliVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00008 Fmt 6633 Sfmt 6602 W:\DISC\81495 81495
5

matologist, Department of Environmental Sciences, University of 

Virginia. 

We welcome you all. Thank you for helping us this morning. Dr. 

Janetos, we will begin with you. You are recognized for 5 minutes 

to give your testimony. 

TESTIMONY OF ANTHONY C. JANETOS, SENIOR FELLOW, THE 

H. JOHN HEINZ III CENTER FOR SCIENCE, ECONOMICS, AND 

THE ENVIRONMENT; THOMAS R. KARL, DIRECTOR, NATIONAL CLIMATIC DATA CENTER; DANIEL A. LASHOF, DEPUTY DIRECTOR, CLIMATE CENTER, NATURAL RESOURCES 

DEFENSE COUNCIL; JAMES J. O’BRIEN, DIRECTOR, CENTER 

FOR OCEAN-ATMOSPHERIC PREDICTION STUDIES, FLORIDA 

STATE UNIVERSITY; ROGER A. PIELKE, SR., PRESIDENTELECT, AMERICAN ASSOCIATION OF STATE CLIMATOLOGISTS, COLORADO STATE CLIMATOLOGIST, AND PROFESSOR, DEPARTMENT OF ATMOSPHERIC SCIENCE, COLORADO STATE UNIVERSITY; AND PATRICK J. MICHAELS, PROFESSOR AND VIRGINIA STATE CLIMATOLOGIST, DEPARTMENT OF ENVIRONMENTAL SCIENCES, UNIVERSITY OF VIRGINIA 

Mr. JANETOS. Thank you, Mr. Chairman. I am pleased to have 

this opportunity to address this committee on the topic of ‘‘Do the 

Climate Models Project a Useful Picture of Climate Change?’’ Mr. GREENWOOD. You might want to pull the microphone. It is 

fairly directional, if you could—Thank you. 

Mr. JANETOS. Thanks. The US National Assessment, ‘‘Climate 

Change Impacts on the United States: The Potential Consequences 

of Climate Variability and Change’’ was released in November of 

2000, following an extensive series of peer reviews and public comment. 

This first document, the overview, was followed about a month 

later by the release of the foundation, a much more extensive, fully 

documented background document that lays out all of the analytical detail and data that were used in the National Assessment. We 

believe that the National Assessment is an extensive synthesis of 

the best available scientific information on this important topic. 

There are three questions about climate change that have dominated discussions. How much climate change is going to occur? 

What will happen as a result? What can countries do about it? 

There are obviously heated opinions about each of these, but the 

issues are real, and it is critical to understand the underlying scientific knowledge about each if sound decisions are to be made. The 

national assessment report focuses on the second of these questions: What will happen as a result? 

A national assessment of the potential impacts of climate change 

was called for in the 1990 legislation that established the U.S. 

Global Change Research Program. For several years, that program 

focused on developing the basic scientific knowledge that the international scientific assessment process, overseen by the IPCC, depends on. 

That scientific research provided increasing evidence that change 

in the climate system is, in fact, occurring. It has become increasVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00009 Fmt 6633 Sfmt 6602 W:\DISC\81495 81495
6

ingly clear that there is a need to understand what is at stake for 

natural resources and human well-being in the U.S. 

In response to this need, in 1998 Dr. John Gibbons, then Science 

Advisor to the President, requested the USGCRP to undertake a 

national assessment originally called for in the legislation. He directed—asked the program to investigate a series of important 

questions: 

What are the current environmental stresses and issues for the 

United States that form a backdrop for additional impacts of climate change? 

How might climate change and variability exacerbate or ameliorate existing problems? 

What are the priority research and information needs that can 

better prepare policymakers for making wise decisions related to 

climate change and variability? What information and answers to 

what key questions could help decisionmakers make better informed decisions about risk, priorities, and responses? What are 

the potential obstacles to information transfer? 

What research is most important to complete over the short term 

and over the long term? 

What coping options exist that can build resilience to current environmental stresses, and also possibly lessen the impacts of climate change? How can we simultaneously build resilience and 

flexibility for the various sectors considering both the short and 

long term implications? 

What natural resource planning and management options make 

most sense in the face of future uncertainty? 

What choices are available for improving our ability to adapt to 

climate change and variability, and what are the consequences of 

those choices? 

A variety of efforts emerged in response to Dr. Gibbons’ quite 

daunting charge. Over 20 workshops were held around the country, 

involving academics, business people representing a range of industries including manufacturing, power generation and tourism, and 

people who work closely on the land and in the water, including resource managers, ranchers, farmers, foresters and fishermen. 

Each workshop identified a range of issues of concern to stakeholders in those regions, many of them quite unrelated to climate 

change per se. Most were followed by the initiation of scientific, 

university led regional studies. 

In addition to these kinds of bottom-up efforts, it was decided 

that it was also necessary to create a national level synthesis of 

what is known about the potential for climate impacts for the U.S. 

as a whole, addressing the issues identified in the regional workshops and national studies. 

This synthesis, obviously, needed to build on the work that had 

begun to emerge from the subsequent regional and national studies, but also to draw on the existing scientific literature and analyses done with the most up to date ecological and hydrological 

models and data that could be obtained. 

The National Assessment Synthesis Team, the NAST, was established by the NSF as an independent committee under the Federal 

Advisory Committee Act specifically in order to carry out this second step. It was made up of experts from academia, industry, govVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00010 Fmt 6633 Sfmt 6602 W:\DISC\81495 81495
7

ernment laboratories, and non-governmental organizations, and in 

order to ensure its openness and independence, all meetings of the 

NAST were open to the public, all documents discussed in its meetings are available through the NSF, as are all the review comments received and the responses to them. 

This is perhaps out of the ordinary for a scientific study, but 

most scientific studies do not focus on issues of such broad and 

deep implications for the country, and about which there is such 

heated debate. 

Our first action was to publish a plan for the conduct of the national synthesis. In addition, five issues, agriculture, water, forests, 

human health, and coastal and marine systems, were selected to be 

topics for national studies. Carrying out this plan was, obviously, 

a major undertaking, with the two reports that I mentioned earlier 

as the two primary national outputs. 

Both of those national outputs have been through extensive review. At the end of 1999 two rounds of technical peer review were 

undertaken, and during the spring of 2000 an additional review by 

about 20 experts who had been outside of the assessment process 

was undertaken. Over 300 sets of comments were received from scientists in universities, industry, NGO’s, and government labs. The 

responses to external comments have been described in comprehensive review memorandums. 

The final stage of that process, a 60-day public comment period 

specifically requested by Congress, after which final revisions were 

then completed. The report was submitted to the President so that 

it could be transmitted to Congress, as called for in the original legislation. Hundreds of additional comments were received during 

the public comment period, each of which was responded to. 

In order to ensure that we did our job well, an oversight panel 

was also established through the offices of the President’s Council 

of Advisors on Science and Technology. That oversight panel was 

chaired by Dr. Peter Raven, Director of the Missouri Botanical Garden and former Home Secretary of the National Academy of 

Sciences, and Dr. Mario Molina, Professor of Atmospheric Chemistry at MIT and recent Nobel prize winner for his research on 

stratospheric ozone depletion. Its membership, like the NAST’s, 

was also drawn from academia, industry, and the NGO’s. It reviewed and approved the plans for the assessment. It reviewed 

each draft of the report, and reviewed the response of our synthesis 

team to all comments. 

It is important to realize that the national assessment does not 

attempt to predict exactly what the future will hold for the U.S. It 

examined the potential implications of two primary climate scenarios, each based on the same assumptions about future global 

emissions of greenhouse gases, the same assumptions that has 

been used as one of many emission scenarios examined by the 

IPCC. 

The two climate scenarios were based on output from two different global climate models used in the IPCC assessments, and we 

believe they were clearly within the range of global—The results 

were clearly within the range of the global annual average temperature changes shown by many such models, one of them near 

the low end of this range and one near the high end. Both also exVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00011 Fmt 6633 Sfmt 6602 W:\DISC\81495 81495
8

hibit warming trends for the U.S. that are larger than the global 

average, but this is not surprising. 

In addition to the two primary models from the Canadian Climate Centre and the Hadley Centre, in different parts of the national process results from climate models developed at the National Center for Atmospheric Research, NOAA’s Geophysical Fluid 

Dynamics Laboratory, NASA’s Goddard Institute for Space Studies, 

and the Max Planck Institute were also used in various aspects of 

the assessment. 

The NAST was aware of the scientific issues surrounding the use 

of regional results form any general circulation models. In the analyses done with the climate models’ regional outputs, simulations 

from the models were used to adjust historically observed data 

using methods that had already been peer reviewed in other studies, in order to depict scenarios that had sufficient regional richness for analysis. So, in fact, we did not use, for the most part, the 

raw data from the GCMs, but used that to adjust historical data. 

In addition to models, the National Assessment used two other 

ways to think about potential future climate. Many groups involved 

in our process used historical climate records to evaluate sensitivities of regions, sectors and natural resources, the climate variability and extremes that have in fact occurred during the 20th Century. 

Looking at real historical climate events, their impacts, and how 

people have adapted, gives valuable insights into potential future 

impacts that complement those provided by model projects. In addition, the assessment used sensitivity analyses, some of which ask 

how and by how much the climate would have to change to result 

in impacts on particular regions and sectors. 

These climate scenarios describe significantly different futures 

that are scientifically plausible, given our current understanding of 

how the climate system operates. That understanding will, no 

doubt, continue to improve. As importantly, they describe separate 

baselines for analysis of how natural ecosystems, agriculture, water 

supplies, etcetera, might change as a result. 

In order to investigate such changes, the potential impacts of 

changes in the physical climate system, the report relies on up to 

date ecological and natural resource models, on empirical observations from the literature, on investigations of how those systems 

have responded to climate variability that has been observed over 

the past century, and on the accumulated scientific knowledge that 

is available about the sensitivity of natural resources to climate, 

and about how the regions of the U.S. have and potentially could 

respond. 

The U.S. National Assessment presents the results for each scenario clearly, and then takes the important additional step of explicitly describing the NAST’s scientific judgment about the uncertainty inherent in each result. Those results that are viewed to be 

robust are described in more certain terms. Those viewed to be the 

result of poorly understood or unreconciled differences between 

models are described in substantially more circumspect language. 

The lexicon of terms used to denote the NAST’s greater or lesser 

confidence is explicitly described in the beginning of the Overview 

report. This helps ensure that the report does not mask important 

9

results by thoughtlessly merging models or overstating the scientific capability for assessing potential impacts. 

Finally, the report begins to identify possible options for adaptation to this changing world. It does not do a complete analysis of 

the costs, benefits or feasibility of these options, however, which 

would be a necessary next step for developing policies to address 

those issues. 

Future assessments will need to consider climate change in the 

context of the suite of environmental stresses that we all face. Perhaps most importantly, our report acknowledges very clearly that 

scientific uncertainties remain and that we can expect surprises as 

this uncontrolled experiment with the earth’s geochemistry plays 

out over the coming decades. 

Thank you very much. 

[The prepared statement of Anthony C. Janetos follows:]

PREPARED STATEMENT OF ANTHONY C. JANETOS, SR. FELLOW, H. JOHN HEINZ III 

CENTER FOR SCIENCE, ECONOMICS, AND THE ENVIRONMENT

I am pleased to have the opportunity to address the US House of Representatives 

Committee on Energy and Commerce, Subcommittee on Oversight and Investigations on the topic of ‘‘The US National Climate Change Assessment: Do the Climate 

Models Project a Useful Picture of Climate Change?’’

The US National Assessment, Climate Change Impacts on the United States: the 

Potential Consequences of Climate Variability and Change was released in November of 2000, following an extensive series of peer reviews and public comment. This 

first document, the Overview, was followed about a month later by the release of 

the Foundation, a much more extensive, fully documented background document 

that lays out all of the analytical detail and data that were used in the National 

Assessment. The National Assessment is an extensive synthesis of the best available scientific information on this important topic. 

There are three questions about climate change that dominate discussions of this 

important topic. How much climate change is going to occur? What will happen as 

a result? What can countries do about it? There are obviously heated political opinions about each of these, but the issues are real, and it is critical to understand the 

underlying scientific knowledge about each if sound decisions are to be made. The 

assessment report focuses on the second of these questions. 

A national assessment of the potential impacts of climate change was called for 

in the 1990 legislation that established the US Global Change Research Program 

(USGCRP). For several years, the research program focused on developing the basic 

scientific knowledge that the international scientific assessment process overseen by 

the Intergovernmental Panel on Climate Change (IPCC) depends on. The IPCC was 

jointly established by the World Meteorological Organization and the United Nations Environmental Programme in 1988. As scientific research has provided compelling evidence that climate change is in fact occurring, it has become increasingly 

clear that there is a need to understand what is at stake for natural resources and 

human well-being in the US. In response to this need, in 1998, Dr. John H. Gibbons, 

then Science Advisor to the President, requested the USGCRP to undertake a the 

national assessment originally called for in the legislation. Dr. Gibbons asked the 

USGCRP to investigate a series of important questions:

• What are the current environmental stresses and issues for the United States 

that form a backdrop for additional impacts of climate change? 

• How might climate change and variability exacerbate or ameliorate existing problems? 

• What are the priority research and information needs that can better prepare policy makers for making wise decisions related to climate change and variability? 

What information and answers to what key questions could help decision-makers make better-informed decisions about risk, priorities, and responses? What 

are the potential obstacles to information transfer? 

• What research is most important to complete over the short term? Over the long 

term? 

• What coping options exist that can build resilience to current environmental 

stresses, and also possibly lessen the impacts of climate change? How can we 

10

simultaneously build resilience and flexibility for the various sectors considering 

both the short and long-term implications? 

• What natural resource planning and management options make most sense in the 

face of future uncertainty? 

• What choices are available for improving our ability to adapt to climate change 

and variability and what are the consequences of those choices? How can we 

improve contingency planning? How can we improve criteria for land acquisition? 

A variety of efforts emerged in response to Dr. Gibbons’ charge. 

Over twenty workshops were held around the country, involving academics, business-people representing a range of industries including manufacturing, power generation and tourism, and people who work closely with land and water ecosystems 

including resource managers, ranchers, farmers, foresters and fishermen. Each 

workshop identified a range of issues of concern to stakeholders in those regions, 

many of them quite unrelated to climate change, per se. Most workshops were followed by the initiation of scientific, university-led regional studies. 

In addition to these kind of ‘‘bottom-up’’ efforts, it was decided that it was also 

necessary to create a national-level synthesis of what is known about the potential 

for climate impacts for the US as a whole, addressing the issues identified in the 

regional workshops and national studies. This synthesis obviously needed to build 

on the work that had begun to emerge from the subsequent regional and national 

studies, but also to draw on the existing scientific literature and analyses done with 

the most up-to-date ecological and hydrological models and data that could be obtained. The National Assessment Synthesis Team (NAST) was established by the 

National Science Foundation as an independent committee under the Federal Advisory Committee Act (FACA) specifically in order to carry out this second step. This 

committee was made up of experts from academia, industry, government laboratories, and non-governmental organizations (NGO’s) (membership list is Attachment 

1). In order to ensure openness and independence, all meetings of the NAST were 

open to the public, all documents discussed in its meetings are available through 

the National Science Foundation, as are all the review comments already received 

and responses to them. This is perhaps out of the ordinary for a scientific study; 

but most scientific studies do not focus on issues of such broad and deep implications for American society, and about which there is such heated rhetoric. 

The NAST’s first action was to publish a plan for the conduct of the national synthesis. In addition, five issues (agriculture, water, forests, health, and coastal and 

marine systems), out of the many identified, were selected to be topics for national 

studies. Carrying out this plan was a major undertaking. The end result has been 

the production of a comprehensive two-volume national assessment report. The 

‘‘Foundation’’ volume is more than 600 pages long, with more than 200 figures and 

tables, with analyses of the five national sectors, and 9 regions that together cover 

the entire US. It is extensively referenced, and a commitment was made that all 

sources used in its preparation were to be open and publicly available. The ‘‘Overview’’ volume is about 150 pages long, written in a style that is more accessible to 

the lay public, and summarizes the Foundation in a way that is understandable and 

informative, and which we are confident is scientifically sound. Both documents 

have already been through extensive review. At the end of 1999, two rounds of technical peer review were undertaken, and during the spring of 2000, an additional review by about 20 experts outside the assessment process was undertaken. Over 300 

sets of comments have been received from scientists in universities, industry, 

NGO’s, and government laboratories. The responses to all external comments have 

been described in comprehensive review memorandums. The final stage of the process, a 60 day public comment period specifically requested by Congress, after which 

final revisions was then completed, and the report was submitted to the President 

so that it could be transmitted to Congress, as called for in the original legislation. 

Hundreds of additional comments were received during the public comment period, 

each of which was responded to. 

In order to ensure that the NAST carried out its charge well, an oversight panel 

was also established through the offices of the President’s Council of Advisors on 

Science and Technology (membership list is Attachment 2). The oversight panel was 

chaired by Dr. Peter Raven, Director of the Missouri Botanical Garden and former 

Home Secretary of the National Academy of Sciences, and Dr. Mario Molina, Professor of Atmospheric Chemistry at MIT, and recent Nobel-prize winner for his research on stratospheric ozone depletion. Its membership, like the NAST’s, was also 

drawn from academia, industry, and NGO’s. It reviewed and approved the plans for 

the assessment, reviewed each draft of the report, and reviewed the response of the 

NAST to all comments. 

11

What have been the results of this extraordinarily open process? What assumptions drive the analysis? What conclusions have been reached? 

It is important to realize that the national assessment does not attempt to predict 

exactly what the future will hold for the US. It examined the potential implications 

of two primary climate scenarios, each based on the same assumptions about future 

‘‘business as usual’’ global emissions of greenhouse gases that the IPCC has used 

for many of its analyses. The two climate scenarios were based on output from two 

different global climate models used in the IPCC assessment. They are clearly within the range of global annual average temperature changes shown by many such 

models, one near the low and one near the high end of the range. Both exhibit 

warming trends for the US that are larger than the global average. This is not surprising. For many years, one of the most robust results of global climate models has 

been that greater warming is expected in more northerly latitudes, and that land 

surfaces are expected to warm more than the global average. We have used assumptions that are entirely consistent with those used by the IPCC. In addition to the 

two primary models from the Canadian Climate Centre and the Hadley Centre, results from climate models developed at the National Center for Atmospheric Research, NOAA’s Geophysical Fluid Dynamics Laboratory, NASA’s Goddard Institute 

for Space Studies, and the Max Planck Institute were also used in various aspects 

of the Assessment. 

The NAST was aware of the scientific issues surrounding the use of regional results from any general circulation models. In the analyses done with the climate 

models’ regional outputs, simulations from the models were used to adjust historically observed data in order using methods that had already been peer-reviewed in 

other studies, in order to depict scenarios that had sufficient regional richness for 

analysis. 

In addition to models, the Assessment used two other ways to think about potential future climate. First, it used historical climate records to evaluate sensitivities 

of regions and sectors to climate variability and extremes that have occurred in the 

20th century. Looking at real historical climate events, their impacts, and how people have adapted, gives valuable insights into potential future impacts that complement those provided by model projections. In addition, the Assessment used sensitivity analyses, which ask how, and how much, the climate would have to change 

to bring major impacts on particular regions and sectors. 

These climate scenarios describe significantly different futures that are scientifically plausible, given our current understanding of how the climate system operates. As importantly, they describe separate baselines for analysis of how natural 

ecosystems, agriculture, water supplies, etc. might change as a result. In order to 

investigate such changes, i.e. the potential impacts of climate changes, the report 

relies on up-to-date models, on empirical observations from the literature, on investigations of how these systems have responded to climate variability that has been 

observed over the past century in the US, and on the accumulated scientific knowledge that is available about the sensitivities of resources to climate, and about how 

the regions of the US have and potentially could respond. 

One additional important point about the scenarios should be mentioned. The report does not average the results of models that disagree; it explicitly avoids doing 

so. The best example of this is in the analysis of potential changes in precipitation, 

where the two models used to create the scenarios give quite different results for 

some areas of the US. We have chosen to highlight these differences and explain 

that regional-scale precipitation projections are much more uncertain compared with 

temperature, rather than attempting to merge the results or guess which is more 

likely. The knowledge that the direction of precipitation change in some areas is 

quite uncertain is valuable for planning purposes, and clearly represents and important research challenge. There is however, consistency among models and observations on other aspects of precipitation changes. For example, both models and observations show an increase in the proportion of precipitation derived from heavy and 

extreme events as the climate warms. So, both types of information are pertinent 

to help with the identification of potential coping actions. In this respect, the report 

follows the procedure that the IPCC itself uses for its global impacts reports, each 

of which examines the potential impacts for entire continents. 

The US national assessment presents the results for each scenario clearly, and 

then takes the important additional step of explicitly describing the NAST’s scientific judgment about the uncertainty inherent in each result. Those results that 

are viewed to be robust are described in more certain terms; those viewed to be the 

result of poorly understood or unreconciled differences between models are described 

in more circumspect language. The lexicon of terms used to denote the NAST’s 

greater or lesser confidence is explicitly described in the beginning of the Overview 

report. This helps ensure that the report does not mask important results by 

12

thoughtlessly merging models, or overstating the scientific capability for assessing 

potential impacts. Finally, the report begins to identify possible options for adaptation to this changing world. It does not do a complete analysis of the costs, benefits, 

or feasibility of these options however, which is a necessary next step for developing 

policies to address these issues. 

The report’s key findings present important observations for all Americans: 

1. Increased warming. Assuming continued growth in world greenhouse gas emissions, the climate models used in this Assessment project that temperatures in the 

US will rise 5-10°F (3-5°C) on average in the next 100 years. 

2. Differing regional impacts. Climate change will vary widely across the US. 

Temperature increases will vary somewhat from one region to the next. Heavy and 

extreme precipitation events are likely to become more frequent, yet some regions 

will get drier. The potential impacts of climate change will also vary widely across 

the nation. 

3. Vulnerable ecosystems. Many ecosystems are highly vulnerable to the projected 

rate and magnitude of climate change. A few, such as alpine meadows in the Rocky 

Mountains and some barrier islands, are likely to disappear entirely in some areas. 

Others, such as forests of the Southeast, are likely to experience major species shifts 

or break up. The goods and services lost through the disappearance or fragmentation of certain ecosystems are likely to be costly or impossible to replace. 

4. Widespread water concerns. Water is an issue in every region, but the nature 

of the vulnerabilities varies, with different nuances in each. Drought is an important concern in every region. Floods and water quality are concerns in many regions. Snow-pack changes are especially important in the West, Pacific Northwest, 

and Alaska. 

5. Secure food supply. At the national level, the agriculture sector is likely to be 

able to adapt to climate change. Overall, US crop productivity is very likely to increase over the next few decades, but the gains will not be uniform across the nation. Falling prices and competitive pressures are very likely to stress some farmers, 

while benefiting consumers. 

6. Near-term increase in forest growth. Forest productivity is likely to increase 

over the next several decades in some areas as trees respond to higher carbon dioxide levels. Over the longer term, changes in larger-scale processes such as fire, insects, droughts, and disease will possibly decrease forest productivity. In addition, 

climate change is likely to cause long-term shifts in forest species, such as sugar 

maples moving north out of the US. 

7. Increased damage in coastal and permafrost areas. Climate change and the resulting rise in sea level are likely to exacerbate threats to buildings, roads, power 

lines, and other infrastructure in climatically sensitive places. For example, infrastructure damage is related to permafrost melting in Alaska, and to sea-level rise 

and storm surge in low-lying coastal areas. 

8. Adaptation determines health outcomes. A range of negative health impacts is 

possible from climate change, but adaptation is likely to help protect much of the 

US population. Maintaining our nation’s public health and community infrastructure, from water treatment systems to emergency shelters, will be important for 

minimizing the impacts of water-borne diseases, heat stress, air pollution, extreme 

weather events, and diseases transmitted by insects, ticks, and rodents. 

9. Other stresses magnified by climate change. Climate change will very likely 

magnify the cumulative impacts of other stresses, such as air and water pollution 

and habitat destruction due to human development patterns. For some systems, 

such as coral reefs, the combined effects of climate change and other stresses are 

very likely to exceed a critical threshold, bringing large, possibly irreversible impacts. 

10. Uncertainties remain and surprises are expected. Significant uncertainties remain in the science underlying regional climate changes and their impacts. Further 

research would improve understanding and our ability to project societal and ecosystem impacts, and provide the public with additional useful information about options for adaptation. However, it is likely that some aspects and impacts of climate 

change will be totally unanticipated as complex systems respond to ongoing climate 

change in unforeseeable ways. 

Given these findings it is clear that climate impacts will vary widely across the 

Nation, as one would expect for a country as large and ecologically diverse as the 

US. Natural ecosystems appear to be highly vulnerable to climate changes of the 

magnitude and rate which appear to be likely; some ecosystems surprisingly so. The 

potential impacts on water resources are an important issue in every region examined, although the nature of the concern is very different for the mountainous West 

than for the East. The potential for drought is a concern across the country. The 

nation’s food supply appears secure, but there are very likely to be regional gains 

13

and losses for farmers, leading to a more complex picture on a region-by-region 

basis. Forests are likely to grow more rapidly for a few decades because of increasing carbon dioxide concentrations in the atmosphere, but it is unclear whether those 

trends will be maintained as the climate system itself changes, leading to other disturbances such as fire and pest outbreaks. However, the climate change itself will, 

over time, lead to shifts in the tree species in each region of the country, some of 

them potentially quite profound. Coastal areas in many parts of the US and the permafrost regions of Alaska are already experiencing disruptions from sea-level rise 

and recent regional warming; these trends are likely to accelerate. Climate change 

will very likely magnify the cumulative impacts of other environmental stresses 

about which people are already concerned, such as air and water pollution, and 

habitat destruction due to development patterns. There are clearly links between 

human health, current climate, and air pollution. The future vulnerability of the US 

population to the health impacts of climate change depends on our capacity to adapt 

to potential adverse changes. Many of these adaptive responses are desirable from 

a public health perspective irrespective of climate change. Future assessments need 

to consider climate change in the context of the suite of environmental stresses that 

we all face. Perhaps most importantly, the report acknowledges very clearly that scientific uncertainties remain, and that we can expect surprises as this uncontrolled 

experiment with the Earth’s geochemistry plays out over the coming decades. 

ATTACHMENT 1

NATIONAL ASSESSMENT SYNTHESIS TEAM MEMBERS

Jerry M. Melillo, Co-chair, Ecosystems Center, Marine Biological Laboratory; Anthony Janetos, Co-chair, World Resources Institute; Thomas R. Karl, Co-chair, 

NOAA, National Climatic Data Center; Robert Corell (from January 2000), American Meteorological Society and Harvard University; Eric J. Barron, Pennsylvania 

State University; Virginia Burkett, USGS, National Wetlands Research Center; 

Thomas F. Cecich, Glaxo Wellcome, Inc.; Katharine Jacobs, Arizona Department of 

Water Resources; Linda Joyce USDA Forest Service; Barbara Miller, World Bank; 

M. Granger Morgan, Carnegie Mellon University; Edward A. Parson (until January 

2000), Harvard University; Richard G. Richels, EPRI; and David S. Schimel, National Center for Atmospheric Research. Additional Lead Authors; David Easterling 

(NOAA National Climatic Data Center); Lynne Carter (National Assessment Coordination Office); Benjamin Felzer (National Center for Atmospheric Research); John 

Field (University of Washington); Paul Grabhorn (Grabhorn Studio); Susan J. 

Hassol (Aspen Global Change Institute); Michael MacCracken (National Assessment 

Coordination Office); Joel Smith (Stratus Consulting); and Melissa Taylor (National 

Assessment Coordination Office). 

ATTACHMENT 2

INDEPENDENT REVIEW BOARD OF THE PRESIDENT’S COMMITTEE OF ADVISERS ON

SCIENCE AND TECHNOLOGY (PCAST)

Peter Raven, Co-chair, Missouri Botanical Garden and PCAST; Mario Molina, Cochair, MIT and PCAST; Burton Richter, Stanford University; Linda Fisher, Monsanto; Kathryn Fuller, World Wildlife Fund; John Gibbons, National Academy of 

Engineering; Marcia McNutt, Monterey Bay Aquarium Research Institute; Sally 

Ride, University of California San Diego and PCAST; William Schlesinger, Duke 

University; James Gustave Speth, Yale University; and Robert White, University 

Corporation for Atmospheric Research, and Washington, Advisory Group.

Mr. GREENWOOD. Thank you, Dr. Janetos. Thank you very much 

for your testimony. 

Dr. Karl. 

TESTIMONY OF THOMAS R. KARL 

Mr. KARL. Good morning, Chairman Greenwood and members of 

the subcommittee. I was one of the three co-chairs of the report of 

the National Assessment Team. As Dr. Janetos has indicated, the 

synthesis team was comprised of scientists and other specialists 

from universities, industries, governments and non-governmental 

organizations. 

14

The National Assessment reports are not policy positions or official statements of the U.S. Government. Rather, they were produced by a selected set of members of the scientific community and 

offered to the government for its consideration. I am very pleased 

to have this opportunity to present the testimony regarding the 

basis for the scenarios of the 21st century climate used in the National Assessment. 

The purpose of the National Assessment was to synthesize, 

evaluate, and report on what we knew about the consequences of 

climate variability and change for the United States in the 21st 

Century. 

The National Assessment was our first attempt to generate climate scenarios for various regions and sectors across the United 

States. It relied on a number of techniques to develop climate scenarios for the 21st Century, including historical data to examine 

the continuation of trends, the recurrence of past climate extremes, 

climate model simulations in attempt to provide plausible scenarios 

for how the future climate may change, and sensitivity analysis to 

explore the resilience of societal and ecology systems to climate 

fluctuations and change. 

Numerous climate models were used in the National Assessment, 

but the two primary models were selected on the basis of a set of 

objective criteria that I have described in some detail in my written 

testimony. Today, if the assessment were repeated with similar criteria, results of several other models would be included. 

As I described in some detail in my written testimony, in a comparison of the models used in the National Assessment with observations and other models indicates that the two primary model 

used in the National Assessment reflected the state of scientific understanding when the National Assessment was conducted between 

1997 and 2000. 

This had important consequences. For example, the amount of 

summertime precipitation expected over much of the contiguous 

USA as the climate warmed was quite uncertain and required the 

use of several what-if analyses to assess potential impacts. Other 

projected changes were less uncertain, like increased temperatures 

everywhere during all seasons. So the impact analysis could focus 

on the magnitude of the warming as opposed to the sign of the projected changes. 

Interestingly, despite the fact that global models do not agree 

well in the sign of summer precipitation changes, in general climate models indicate that as greenhouse gases increase, on average more intense precipitation will occur. Indeed, observations in 

the USA and elsewhere reflect this today. That is, a greater proportion of the total precipitation occurs in heavy and very heavy precipitation events. 

This attribute of precipitation change was another scenario considered by the sectorial and regional impact and adaptation assessments. Given the many differences among models, wherever feasible the National Assessment relied on model simulations to assess impacts to the greatest extent possible. A particularly noteworthy example comes from the Great Lakes region. Results from 

10 models were used to assess changes in Great Lake levels during 

the 21st Century. 

15

In conclusion, the National Assessment we conducted on the impact of climate change had significant limitations, but was an important first step. Quite clearly, more needs to be done, and such 

efforts can provide more effective decision support tools, help frame 

adaptation mitigation measures to avoid the potential risk and 

harm of climate change, and maximize the potential benefits. 

I want to thank the chairman for allowing me the opportunity to 

describe the rationale used in the National Assessment to develop 

the climate scenarios for the 21st Century. I would be happy to answer any questions later. Thank you. 

[The prepared statement of Thomas R. Karl follows:]

PREPARED STATEMENT OF THOMAS R. KARL, DIRECTOR, NATIONAL CLIMATIC DATA

CENTER, NATIONAL ENVIRONMENTAL SATELLITE, DATA, AND INFORMATION SERV- ICES, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION

INTRODUCTION

Good morning, Chairman Greenwood and members of the Subcommittee. I am 

Thomas R. Karl, Director of NOAA’s National Climatic Data Center. I was invited 

to appear today because I was one of the three Co-Chairs of the Report of the National Assessment Synthesis Team (NAST). 

I would like to begin by emphasizing that the reports of the National Assessment 

Synthesis Team are not a product of the U.S. Government, and they do not represent government policy. In fact, they have sometimes been quite controversial. 

The National Assessment Synthesis Team is an advisory committee chartered under 

the Federal Advisory Committee Act. The NAST reports are not policy positions or 

official statements of the U.S. government. Rather, they were produced by selected 

members of the scientific community and offered to the government for its consideration. 

The Synthesis Team was comprised of individuals drawn from governments, universities, industry, and non-governmental organizations that had responsibility for 

broad oversight of the National Assessment entitled ‘‘Climate Change Impacts on 

the United States—The Potential Consequences of Climate Variability and Change.’’

The purpose of the Assessment was to synthesize, evaluate, and report on what we 

presently know—and don’t know—about the potential consequences of climate variability and change for the United States in the 21st century. It attempted to review 

climate vulnerabilities of particular regions of the nation and of particular sectors, 

and sought to provide a number of adaptation measures to reduce the risk, and 

maximize the potential benefits and opportunities of climate change, whatever its 

cause. The National Assessment was conducted from 1997 to 2000 and was our first 

attempt to generate climate scenarios for various regions and sectors across the 

United States, which turned out to be a very challenging task. I am very pleased 

to have this opportunity to present testimony regarding the basis for the scenarios 

of 21st century climate used in the National Assessment. 

As a basis for the National Assessment, and in the context of the uncertainties 

inherent in looking forward 100 years, the NAST pursued a three-pronged approach 

to considering how much the climate may change. The three approaches involved 

use of: (1) historical data to examine the continuation of trends or recurrence of past 

climatic extremes; (2) comprehensive, state-of-the-science (though still with significant limitations), model simulations to provide plausible scenarios for how the future climate may change; and (3) sensitivity analyses that can be used to explore 

the resilience of societal and ecological systems to climatic fluctuations and change. 

Of particular interest for this hearing is the second of these approaches, and that 

is where I will focus my remarks. As a pretext however, I note that the National 

Assessment rests on a combination of these approaches. 

DEVELOPING MODEL-BASED SCENARIOS FOR THE 21ST CENTURY

Projecting changes in factors that influence climate 

Because future trends in fossil fuel use and other human activities are uncertain, 

the Intergovernmental Panel on Climate Change (IPCC) has developed a set of scenarios for how the 21st century may evolve. These scenarios consider a wide range 

of possibilities for changes in population, economic growth, technological development, improvements in energy efficiency and the like. The two primary climate scenarios used in the National Assessment were based on a mid-range emission sceVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00019 Fmt 6633 Sfmt 6621 W:\DISC\81495 81495
16

nario used in the second IPCC report. This scenario assumes no major changes in 

policies to limit greenhouse gas emissions. Other important assumptions in the scenario are that by the year 2100:

• world population is projected to nearly double to about 11 billion people; 

• the global economy is projected to continue to grow at about the average rate it 

has been growing, reaching more than ten times its present size; 

• increased use of fossil fuels are projected to triple CO2 emissions and raise sulfur 

dioxide emissions, resulting in atmospheric CO2 concentrations of just over 700 

parts per million; and 

• total energy produced each year from non-fossil sources such as wind, solar, biomass, hydroelectric, and nuclear are projected to increase to more than ten 

times its current amount, providing more than 40% of the world’s energy, rather than the current 10%. 

There are a number of other important factors besides fossil fuel emissions that 

cause climate to change and vary. These were not part of the scenario used to drive 

climate change in the two primary models used in the National Assessment, because 

at the time of the National Assessment these simulations were not available. Figure 

1 depicts the magnitude of these other climate forcings that were omitted from the 

emission scenario. Clearly, the two largest forcings are those related to increases in 

greenhouse gases and aerosols, both included in the two primary models used in the 

National Assessment. The addition of other forcings are an important consideration 

for improvement of future assessments, for example the 

role of black carbon aerosols, and a more thorough treatment of land vegetative 

feedback effects which become quite important on local and regional space scales 

compared to global scales, e.g., the urban heat island. 

Which models to use? 

The NAST developed a set of guidelines to aid in narrowing the set of primary 

model simulations to be considered for use by the Assessment teams. This helped 

ensure a degree of consistency across the broad number of research teams participating in the Assessment. These guidelines included various aspects related to the 

structure of the model itself, the character of the simulations, and the availability 

of the needed results. Specifically this meant that the models must, to the greatest 

extent possible:

• be coupled atmosphere-ocean general circulation models that include comprehensive representations of the atmosphere, oceans, and land surface, and the key 

feedbacks affecting the simulation of climate and climate change; 

• simulate the evolution of the climate through time from at least as early as the 

start of the detailed historical record in 1900 to at least as far as into the future 

as the year 2100 based on a well-understood scenario for changes in atmospheric composition that takes into account time-dependent changes in greenhouse gas and aerosol concentrations; 

• provide the highest practicable spatial and temporal resolution (roughly 200 miles 

[about 300 km] in longitude and 175 to 300 miles [about 275 to 425 km] in latitude over the central US); 

• include the diurnal cycle of solar radiation in order to provide estimates of 

changes in minimum and maximum temperature and to be able to represent 

the development of summertime convective rainfall; 

• be capable, to the extent possible, of representing significant aspects of climate 

variations such as the El Nin ̃ o-Southern Oscillation cycle; 

• have completed their simulations in time to be processed for use in impact models 

and to be used in analyses by groups participating in the National Assessment; 

• be models that are well-understood by the modeling groups who participated in 

the development of the Third Assessment Report of the Intergovernmental 

Panel on Climate Change (IPCC) in order to ensure comparability between the 

US efforts and those of the international community; 

• provide a capability for interfacing their results with higher-resolution regional 

modeling studies (e.g., mesoscale modeling studies using resolutions finer by a 

factor of 5 to 10); and 

• allow for a comprehensive array of their results to be provided openly over the 

World Wide Web. 

Including at least the 20th century in the simulation adds the value of comparisons between the model results and the historical record and can be used to help 

initialize the deep ocean to the correct values for the present-day period. Having results from models with specific features, such as simulation of the daily cycle of temperature, which is essential for use in cutting edge ecosystem models, was important 

for a number of applications that the various Assessment teams were planning. 

17

At the time of the National Assessment only two models, the Canadian Climate 

Centre Model and the United Kingdom’s Hadley Centre model, were able to satisfactorily meet these criteria. Today however, if the Assessment were repeated with the 

same criteria, several more models would meet these criteria, including modeling efforts in the USA. Let me emphasize the importance of this, which represents another limitation of the National Assessment. In 1998 the Climate Research Council 

(which I chaired) of the National Research Council issued a report, Capacity of U.S. 

Climate Modeling to Support Climate Change Assessment Activities. While improvements in model capability have occurred during the past four years, key findings 

from the CRC report are worthy of note: 

The CRC finds that the United States lags behind other countries in its ability 

to model long-term climate change. Those deficiencies limit the ability of the 

United States to predict future climate states... Although collaboration and free 

and open information and data exchange with foreign modeling centers are critical, it is inappropriate for the United States to rely heavily upon foreign centers to provide high-end capabilities. There are a number of reasons for this, 

including the following: (1) U.S. scientists do not necessarily have full, open and 

timely access to output from European models...(2) Decisions that might substantially affect the U.S. economy might be made based upon considerations of 

simulations (e.g. nested-grid runs) produced by countries with different priorities than those of the United States. 

Furthermore, the report noted, ‘‘While leading climate models are global in scale, 

their ability to represent small-scale, regionally dependent processes... can currently only be depicted in them using high-resolution, nested grids. It is reasonable 

to assume that foreign modeling centers will implement such nested grids to most 

realistically simulate processes on domains over their respective countries which 

may not focus on or even include the United States.’’

The use of observations 

Observations were an essential part of developing climate scenarios for the 21st 

century in the National Assessment. Reliance on model simulations provides only 

a limited opportunity to investigate the consequences of climate variability and 

change. To minimize this limitation, in the National Assessment the historical 

record was used to help determine regional and sector specific sensitivities to climate changes and variations of differing, but contextual realistic changes. 

The observations were also used to understand how the models simulated present 

and past climate (see Figure 2), and to correct a number of model biases. While climate models have shown significant improvement over recent decades, and the models used in the National Assessment were among the world’s best, there were a 

number of shortcomings in applying the models to study potential regional-scale 

consequences of climate change. This is a fundamental limitation to the results of 

the National Assessment, and should be kept in mind. In the National Assessment, 

several methods were used in an attempt to address these problems. Most importantly, the output from the primary models (the Hadley and Canadian) for temperature and precipitation were passed through a set of standardization processing algorithms to re-calibrate the model simulations with the observations. This is especially 

important in areas of complex terrain such as mountainous regions of the West were 

model resolution was insufficient to adequately resolve detailed small-scale climate 

characteristics. The processing procedure accounted for at least some of the shortcomings and biases in the models. So, the model scenario results used in the impact 

assessments were often adjusted to remove the systematic differences with observations that were present in the model simulations. Such a procedure is similar to 

what is now being implemented in daily weather forecasting, where actual model 

projections are not used, but rather the historical statistical and dynamical relationships between the weather model forecasts and actual observations are used to generate local weather forecasts. This adjustment process is fully described in the foundation report of the National Assessment. 

In addition, some of the regional teams applied other types of ‘‘down-scaling’’ techniques to the climate model results in order to derive estimates of changes occurring 

at a finer spatial resolution. One such technique has been to use the global climate 

model results as boundary conditions for mesoscale models that cover some particular region (e.g., the West Coast with its Sierra Nevada and Cascade Mountains). 

These models are able to represent important processes and mountain ranges on 

finer scales than do global climate models. These small-scale simulations however, 

have not been as well tested as global models and are very computer intensive. It 

has not yet been possible to apply the techniques nationally or for the entire 20th 

or 21st centuries. With the rapid advances in computing power expected in the future, this approach should become more feasible for future assessments. To overVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00021 Fmt 6633 Sfmt 6621 W:\DISC\81495 81495
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come the computational limitations of mesoscale models, some of the Assessment 

Teams developed and tested empirically based statistical techniques to estimate 

changes at finer scales than the global climate models, and these efforts are discussed in the various regional assessment reports. These techniques have the important advantage of being based on observed weather and climate relationships, but 

have the shortcoming of assuming that the relationships prevailing today will not 

change in the future. 

Another type of tool developed for use in the sensitivity analyses were statistical 

models and weather generators used to calculate probabilities of unusual weather 

and climate events. These models enabled impact analysts to compose ‘‘what if’’

questions for strings of weather and climate events that could be important to their 

specific sector or region. Other approaches focused on using a variety of other types 

of observational data. 

EVALUATION OF THE MODELS

Among the tests that have been used to evaluate the skill of climate models have 

been evaluations of climate model output to simulate present weather and climate, 

the cycle of the seasons, climatic variations over the past 20 years (the time period 

when the most complete data sets are available), climatic changes over the past 100 

to 150 years during which the world has warmed, and climatic conditions for periods 

in the geological past when the climate was quite different than at present. 

There are so many kinds of evaluations that can be made it is not possible to provide one test to ascertain the appropriateness of any model for climate impact assessments. For example, models may be expected to reproduce the past climate for 

hemispheric and global averages on century time-scales because much of the climate 

noise due to seasonal to inter-annual climate variability tends to be less important. 

This includes many of the important climate oscillations such as the El Nino, the 

North Atlantic Oscillation, the Pacific Decadal Oscillation, and others. Because models generally replicate the chaotic behavior of the natural climate, the climate models simulate their own year-by-year climates and they will not produce the precise 

timing of these events to match the observations. On the other hand, the climate 

models may be expected to reproduce the statistical distribution of these events. So, 

to compare models to observations it is important to be able to average out these 

natural variations that can have very large impacts for given regions in specific 

years. For this reason in the National Assessment comparisons of the model simulations with observations on regional and subregional levels were made by averaging 

over multiple decades or longer. 

In conducting climate model evaluations it is tempting to prefer those models 

where the simulations most closely match the observations, but several complications must be accounted for in such intercomparisons. First, there are inherent errors and biases in our observational data. Models, even if they are provided perfect 

forcing scenarios and had perfect chemistry, physics and biology, should not be expected to perfectly match imperfect observations. By cross comparing observations 

from differing data sets and observing systems we can roughly estimate some of the 

observational errors and biases. Second, because of the chaotic nature of the climate, 

we cannot expect to match the year-by-year or decade-by-decade fluctuations in temperature that have been observed during the 20th century. Third, the particular 

model simulations used in the National Assessment did not include consideration 

of all of the effects of human-induced and naturally-induced changes that are likely 

to have influenced the climate, including changes in stratospheric and tropospheric 

ozone, volcanic eruptions, solar variability, and changes in land cover (and associated changes relating to biomass burning, dust generation, etc.). Finally, while it is 

desirable for model simulations not to have significant biases in representing the 

present climate, having a model that more accurately reproduces the present and 

past climate does not necessarily mean that projections of changes in climate developed using such a model would provide more accurate projections of climate change 

than models that do not give as accurate simulations. This can be the case for at 

least two reasons. First, what matters most for simulation of changes in future climate is proper treatment of the feedbacks that contribute to amplifying or limiting 

the changes, and accurate representation of the 20th century does not guarantee 

this will be the case. Second, because projected changes are calculated by taking differences between perturbed and unperturbed cases, the effects of at least some of 

the systematic biases present in a model simulation of the present climate can be 

eliminated. While potential nonlinearities and thresholds make it unlikely that all 

biases can be removed in this manner, it is also possible that the projected changes 

calculated by such a model could turn out to be more accurate than simulations 

with a model that provided a better match to the 20th century climate. 

19

Recognizing these many limitations, evaluation of the simulations from the Canadian and Hadley models are briefly summarized here to give an indication of the 

kinds of tests climate scientists have completed to assess the general adequacy of 

the models for use in assessing the impacts of climate change and variability. As 

depicted in Figure 2 both primary models capture the rise in global temperature 

since the late 1970s, but do not do as well in reproducing decadal variations. The 

question of how these two models compare to other climate models, several of which 

were not available at the time of the National Assessment, is addressed in Figure 

3. Note that the scaling factor required to match in the increase in temperature during the 20th century for all models is close to one, except for the Canadian Climate 

Model which is somewhat less than one, reflecting the relatively high sensitivity of 

this model to increases in greenhouse gases, although the scaling factor in a later 

version of the model (CGCM2 in Figure 3) is closer to one. It is also noteworthy that 

the later version of the Hadley Centre Model very closely reproduces the rate of 

20th century warming when a more complete set of forcings, indirect sulfate forcing 

and tropospheric ozone, is added to the model. Another test of a model’s ability to 

reproduce 20th Century global temperatures is to compare the annual temperatures 

generated by the models with the observations. To assess relative skill, errors can 

be compared to projections based on temperature persistence. That is, always predicting the annual mean temperature to be equal to the longer-term mean over the 

length of the averaging period centered on either side of the prediction year. Figure 

4 shows some results of such a test for averaging periods from 10 to 50 years. This 

is a difficult test for a model to show skill because the persistence forecast actually 

includes information about the annual mean temperature both before and after the 

‘‘prediction year.’’ In all cases the model simulations have smaller errors than the 

persistence based projection, indicating significant skill. 

So, analyses at the global scale for the two primary models used in the National 

Assessment indicate that there is general agreement with the observed long-term 

trend in temperature over the 20th century, but the Canadian Climate Model is significantly more sensitive to greenhouse gases compared to the Hadley Centre Model, 

and may be thought of as the ‘‘hotter’’ of the two models. This higher climate sensitivity of the Canadian model may be due to projection an earlier melting of the Arctic sea ice than the Hadley model. It is not yet clear how rapidly this melting may 

take place. 

The question as to whether the Canadian Climate Model is an outlier can be addressed in Figure 5 where the global warming rate has been plotted for various 

models with similar forcings of greenhouse gases and sulfate aerosols. The Canadian 

Climate Model is seen to have a relatively high sensitivity to increases in greenhouse gases compared to other models, but its sensitivity is quite comparable to a 

model not used in the National Assessment, NOAA’s Geophysical Fluid Dynamics 

Laboratory R15 model. So, although the Canadian model does appear to be one of 

the more sensitive models to increases in greenhouse gases, it is not an outlier. By 

comparison the Hadley Centre model appears to have moderate sensitivity to increases in greenhouse gases. 

The National Assessment was not performed on global space scales, so it is important to understand the differences between model simulations and observations on 

regional scales. As part of a long-term Climate Model Intercomparison Project 

(CMIP2), Dr. Benjamin Santer of the Lawrence Livermore National Laboratory has 

recently compared results from a number of climate models related to their ability 

to reproduce the annual mean precipitation and the annual cycle of precipitation 

across North America. The results of this study, which included the two primary 

models used in the National Assessment, are depicted in Figures 6 and 7. The figure 

shows the correlation between the patterns of the model output and the observations (the y-axis) along with a measure of the differences in actual precipitation (the 

x-axis). If there were no errors in our observing capability, a perfect model would 

reproduce the observations exactly and have perfect correlation with the observations, the difference between any observed model grid point and observational grid 

point would be zero, and it would appear as a point in the far upper left corner of 

the plot. By comparing two different observational data sets we can get an estimate 

of the errors in the observations and this has been done in Figures 6 and 7 by comparing two different 20-year climatologies over North America by two different research groups. So, no model should be expected to be in the quadrant of the diagram 

to the upper left of the less than perfect observational data sets. It is clear in Figures 6 and 7 that the Hadley Centre model used in the National Assessment reproduces the observations better than all other models, while the Canadian Climate 

Centre Model does not do as well, but is by no means an outlier. 

Although the changes in global scale features and the regional simulations of precipitation of the two primary models are seen to be rather typical of other models, 

20

there are important issues on regional scales that suggest that significant uncertainties remain in our ability to effectively use these models for impact assessments. 

For example, problems with the way these climate models simulate ENSO variability suggest that the projected pattern of changes may not be definitive. Also, as 

illustrated by the different projections of changes in summer precipitation used in 

the National Assessment in the Southeast, there are often several processes that 

can contribute to the pattern of change. The same process can lead to different projections of changes when imposed on a slightly different base state of the climate. 

For example, the proportion of the oceans that are frozen versus liquid, the amount 

of snow cover extent, the dryness of the ground surface, the strength of North Atlantic deep water circulation, etc., all can play important roles. In addition, the different representations of land surface processes, clouds, sea-ice dynamics, horizontal 

and vertical resolution, as well as many other factors included in different climate 

models, can have an important impact on projections of changes in regional precipitation. This dependence occurs because precipitation, unlike atmospheric dynamics, 

is a highly regionalized feature of the climate, depending on the interaction of many 

processes, many of which require a set of model parameterizations. Given these 

many limitations, in the National Assessment the model simulations were viewed 

as projections not as predictions. The significance of this distinction can be seen in 

the following quote from the recently-released Climate Action Report 2002: ‘‘Use of 

these model results is not meant to imply that they provide accurate predictions of 

the specific changes in climate that will occur over the next hundred years. Rather, 

the models are considered to provide plausible projections of potential changes for 

the 21st century. For some aspects of climate, the model results differ. For example, 

some models, including the Canadian model [used in this Assessment] project more 

extensive and frequent drought in the United States, while others, including the 

Hadley model [the other model used in the Assessment] do not. As a result, the Canadian model suggests a hotter and drier Southeast during the 21st century, while 

the Hadley model suggests warmer and wetter conditions. Where such differences 

arise, the primary model scenarios provide two plausible, but different alternatives.’’

HOW WERE THE MODEL PROJECTIONS USED?

They model projections were used as indications of the types of consequences that 

might result. For example, as evident in Figure 2, although the emissions scenarios 

are the same for the Canadian and Hadley simulations, the Canadian model scenario projects more rapid global warming than does the Hadley model scenario. This 

greater warming in the Canadian model scenario occurs in part because the Hadley 

model scenario projects a wetter climate at both the national and global scales, and 

in part because the Canadian model scenario projects a more rapid melting of Arctic 

sea ice than the Hadley model scenario. 

Recognizing that all model results are plausible projections rather than specific 

quantitative predictions, the consistency of the temperature projections of the primary models used for the National Assessment were assessed in a broader context. 

Figure 8 illustrates how this strategy was used. It is apparent that virtually all 

models consistently show a much greater than the global average warming over the 

US during winter and a greater than average warming during summer, except for 

Alaska. So, in the National Assessment all the scenarios of temperature change related to increased temperatures and the increases were often as larger or larger 

than the global mean temperature increase. 

Although there are many similarities in the projected changes of temperature 

amongst the many climate models considered by the IPCC (Figure 8), this is not 

true of precipitation changes. In the National Assessment the Hadley Centre model 

often projected significantly wetter conditions compared to the Canadian model, but 

this variation is typical of our present state of understanding as depicted in Figure 

9. Only during winter is there a consistent pattern of a small increase of precipitation among most of the climate models; by contrast during summer there is not 

much agreement about the sign or magnitude of the precipitation change, except for 

a general tendency for more precipitation in the high latitudes of North America. 

The inconsistencies among all the models with respect to summertime mid-latitude 

North American precipitation (Figure 9) were reflected in the two scenarios used in 

the National Assessment, ensuring consideration of a range of possible outcomes. To 

address this range of possible outcomes a number of ‘‘what if’’ scenarios were developed and used in the National Assessment. For example, in the West, although both 

models in the National Assessment projected precipitation increases, a ‘‘what-if’’ scenario of less precipitation was used to broaden the assessment of possible climate 

impacts, vulnerabilities, and adaptation measures. 

21

Interestingly, despite the fact that the global climate models do not agree well on 

the sign of summer precipitation changes, virtually all climate models indicate that 

as greenhouse gases increase more intense precipitation events will occur over many 

areas. Indeed, observations reflect this today in many mid and high latitude land 

areas where data are available for such an assessment. For these reasons and the 

fact an increase in precipitation intensity can effectively be argued from simple thermodynamic considerations, this attribute of precipitation change was an important 

scenario considered by the sectoral and regional impact and adaptation assessments. 

It should also be noted in the National Assessment, due to the nature of the differences among various models, wherever feasible other model simulations were 

used to assess possible impacts. A particularly noteworthy example comes from the 

Great Lakes Region. Results from ten models were used to simulate changes in 

Great Lake levels during the 21st century. All but one of the models suggested 

lower Lake levels. So a combination of the primary models, other climate models, 

and observations were instrumental in identifying key climate impacts and 

vulnerabilities for the 21st Century. 

FUTURE ASSESSMENTS

To build confidence in the projections used for future climate assessments, much 

remains to be done. Further improvements in climate models are needed, especially 

in the representations of clouds, aerosols (and their interactions with clouds), sea 

ice, hydrology, ocean currents, regional orography, and land surface characteristics. 

Improving projections of the potential changes in atmospheric concentrations of 

greenhouse gases, aerosols and land use is important. Climate model simulations 

based on these revised emissions forecasts should provide improved sets of information for assessing climate impacts. In addition to having results from more models 

available, ensembles of simulations from several model runs are needed so that the 

statistical significance of the projections can be more fully examined. As part of 

these efforts, it is important to develop greater understanding of how the climate 

system works (e.g., of the role of atmosphere-ocean interactions and cloud 

feedbacks), to refine model resolution, to more completely incorporate existing understanding of particular processes into climate models, to more thoroughly test 

model improvements, and to augment computational and personnel resources in 

order to conduct and more fully analyze a wider variety of model simulations, including mesoscale modeling studies. 

While much remains to be done that will take time, much can also be done in 

the next few years that can substantially improve the set of products and tools 

available to assess climate impacts. For example, an intensified analysis program 

is needed to provide greater understanding of the changes and the reasons why they 

occur. New efforts to incorporate the interactive effects of changes in land use and 

vegetation in meso-scale and global models will help in understanding local and regional climate change and variability. A better understanding of the changes in 

weather patterns and extremes in relation to global changes is important. Improved 

efforts that combine analysis of the model results with the insights available from 

analysis of historical climatology and past weather patterns needs to be a priority. 

Regional climate scenarios can also be developed using a combination of climate 

model output and dynamical reasoning. More use of mesoscale models is important 

because they can provide higher resolution of spatial conditions. 

In the National Assessment, we were able to consider only one set of emission scenarios rather than a range of emission scenarios. For the future, the actual emissions of greenhouse gases and aerosols could be different than the baseline used. 

Changing the emissions scenario would give increasingly divergent climate scenarios 

as the time horizon expanded. This would likely become important beyond the next 

few decades as different emission scenarios are not likely to significantly affect climate scenarios because of the relatively slow response of the global climate and energy systems, and because a large portion of the change will be due to past emissions. 

As recently stated by the Assistant Secretary for Oceans and Atmosphere, Dr. 

Mahoney, the highest and best use of the scientific information developed in the 

combined United States Global Climate Research Program (USGCRP) and the 

President’s Climate Change Research Initiative (CCRI) could be the development of 

comparative information that will assist decision makers, stakeholders and the general public in debating and selecting optimal strategies for mitigating global change, 

while maintaining sound economic and energy security conditions in the United 

States and throughout the world. Significant progress in developing and applying 

science-based decision tools during the next 1 to 3 years must be a key goal of the 

combined USGCRP and CCRI program. Examples of analyses expected to be comVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00025 Fmt 6633 Sfmt 6621 W:\DISC\81495 81495
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pleted during this time period that would improve our nations ability to conduct a 

subsequent National Assessment include:

• Long-term global climate model projections (e.g., up to the year 2100) for a wide 

selection of potential mitigation strategies, to evaluate the expected range of 

outcomes for the different strategies. 

• Detailed analyses of variations from defined ‘‘base’’ strategies, to investigate the 

importance of specific factors, and to search for strategies with optimum effectiveness. 

• Linked climate change and ecosystem change analyses for several suggested strategies, to search for optimum benefits. 

• Detailed analyses of the outcomes that would be expected from application of the 

wide selection of energy conservation technologies, and carbon sequestration 

strategies, currently being investigated by the National Climate Change Technology Initiative 

SUMMARY

The National Assessment conducted from 1997-2000 was a first step. It relied on 

a number of techniques to develop climate scenarios for the 21st century including: 

historical data to examine the continuation of trends or recurrence of past climatic 

extremes; climate model simulations in an attempt to provide plausible scenarios for 

how the future climate may change; and sensitivity analyses to explore the resilience of societal and ecological systems to climatic fluctuations and change. Numerous climate models were used in the National Assessment, but the two primary 

models were selected on the basis of a set of objective criteria. Today, if the Assessment were repeated with the similar criteria, results of several other models would 

be included. 

Intercomparison of the models used in the National Assessment with observations 

and other models indicates that the two primary models used in the National Assessment reflects the state of scientific understanding approximately 2-3 years ago. 

This had important consequences. For example, the amount of summertime precipitation expected over much of the contiguous USA as the climate warmed was quite 

uncertain and required use of several ‘‘what if’’ analyses to assess potential impacts. 

Other projected changes were more certain, like increased temperatures everywhere, 

during all seasons, and impact analyses could focus on the magnitude as opposed 

to the sign of projected change. 

In conclusion, the National Assessment we conducted on the impact of climate 

variability and change had significant limitations, but was a first step. Quite clearly, more needs to be done and such efforts will provide more effective decision support tools to help frame adaptation and mitigation measures to avoid the risk and 

harm of climate change and maximize its potential benefits. 

It is important to note a major recommendation in the National Research Council’s recent analysis (2001) of some key questions related to Climate Change Science. 

Specifically, that report states that ‘‘the details of the regional and local climate 

change consequent to an overall level of global climate change’’ requires further understanding. The uncertainties that surfaced in generating scenarios for the National Assessment was clearly in our minds when we made this recommendation. 

Resolving these uncertainties will be essential to understanding the scope of any 

climate change impact. Quite clearly, more needs to be done and such efforts will 

provide more effective decision support tools to help frame adaptation and mitigation measures to avoid the potential risk and harm of climate change and maximize 

its potential benefits.

23

Figure 1 Global, annual-mean radiative forcings (Wm-2) due to a number of agents for the 

period from pre-industrial (1750) to present (about 2000). In the National Assessment forcings 

due to greenhouse gases (the first column) and sulfate (the fourth column) were the only forcings 

used in the emission scenario. The height of the vertical bars represent the best estimate value, 

while its absence denotes no best estimate is possible. The vertical line about the rectangular 

bar with ‘‘x’’ provides an estimate of the uncertainty range. (From IPCC, 2001)

Figure 2 Trends of global temperature from observations, the United Kingdom’s Hadley Center Global Climate Model, and the Canadian Climate Center’s Global Climate Model. Trends 

have been smoothed to remove year-to-year high frequency variations.


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24

Figure 3 Estimates of the ‘‘scaling factors’’ by which the amplitude of several model-simulated signals must be multiplied to reproduce the corresponding change in the observed record. 

The vertical lines represent the 5-95% confidence interval due to internal natural variability. 

The models used in the National Assessment were the HadCM2 with greenhouse gases and sulfur (GS) and the CGCM1 with greenhouse gases and sulfur (GS). Abbreviations: GS includes 

greenhouse and sulfate forcing and GSIO includes also includes the indirect effect of sulfate aerosol forcing plus tropospheric ozone forcing. See IPCC(2001) for details.

Figure 4 A comparison of the ability of the Hadley Center and Canadian Climate Center coupled global climate models used in the National Assessment to simulate the 20th century global 

climate compared with using the mean temperature over various time segments to predict yearto-year variations of global temperatures (persistence). Standard errors less than persistence 

based on observations reflect skillful simulations.


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25

Figure 5 The time evolution of the globally averaged temperature change (relative to 1961-

90 mean temperature) for various climate models forced with the emission scenarios used in the 

National Assessment (see IPCC 2001 for details)

Figure 6 Results of a coupled ocean-atmosphere global Climate Model Intercomparison 

Project (CMIP) being conducted by the Lawrence Livermore National Laboratory. This comparison relates to the spatial distribution of annual precipitation across North America. All models 

are compared to the ‘‘Xie/Arkin’’ observational data set. The difference between two differing observation-based data sets reflect observational uncertainties, so we would not expect any model 

to skillfully exceed these differences. All models are evaluated on the basis of pattern correlations with the observations and the relative differences of annual precipitation integrated across 

all model grid points in North America. The Hadley Center climate model used in the National 

Assessment is shown with an ‘‘*’’ and the Canadian Climate Center is shown with a ‘‘#’’ symbol.


g:\graphics\81495.005 g:\graphics\81495.006
26

Figure 7 Similar to Figure 6 except the results relate to the ability of the models to reproduce 

the annual cycle of precipitation.

Figure 8 Analysis of coupled ocean-atmosphere inter-model consistency in regional temperature change based on much greater (40%) than average global warming, greater than average 

warming, less than average warming, inconsistent rates of warming, or cooling for the 21st century based on five model simulations (the Hadley and Canadian models used in the National 

Assessment and three other models used in the IPCC (2001) assessment) with 21st century increases in both greenhouse gases and sulfates (see IPCC 2001 for details).


g:\graphics\81495.007 g:\graphics\81495.008
27

Figure 9 Similar to Figure 8 except for precipitation and a large change represents a change 

in excess of 20% and a small change is between 5 and 20% (see IPCC, 2001 for more details).

Mr. GREENWOOD. We thank you, Dr. Karl. Thank you so much. 

Dr. Lashof. 

TESTIMONY OF DANIEL A. LASHOF 

Mr. LASHOF. Thank you, Mr. Chairman. In summarizing my 

written statement I want to try to make three points. 

The first is on the general value of climate models in looking into 

the future and trying to understand what is going on. 

The second is the fact that the National Assessment and the 

models that underlie it were accepted not just by the Clinton administration. They were reviewed more recently by the Bush administration, showing very broad partisan acceptance of those results. 

Third, I want to present an example of the use of climate models 

to one particular study that we conducted on the effects of global 

warming on trout and salmon expected in the United States. 

So why climate models? Why do we use climate models to examine the effects of global warming. The fact, Mr. Chairman, is that 

we only have one earth, and it is, therefore, impossible to conduct 

a standard controlled experiment where you take one plot and 

apply an experimental drug or chemical to it and another plot 

which is the control, which you leave undisturbed. 

We are, in fact, conducting an experiment on the earth by adding 

heat trapping carbon dioxide and other greenhouse gases to the atmosphere, but we have no control. 

So the only way we can examine what the effects of the experiment that we are already engaged in would be is to have climate 

models which represent the earth based on the best available data 

we have from the atmosphere of the oceans, the land surface, and 

mathematical descriptions of the fundamental laws of physics. 

Those are run in a simulation on a computer, and that is what we 

call climate modeling. 

Of course, this type of simulation model is not unique to climates. It is used to simulate everything from—We test crash cars 

in computers. We test fly airplanes in computers. We test detonate


g:\graphics\81495.009
28

nuclear weapons in computers. In fact, it is no accident that Lawrence Livermore National Laboratory does both climate modeling 

and nuclear weapons simulations using some of the most advanced 

computers in the world. So the basic idea is we are running this 

experiment on the climate, and we want to know what is going to 

happen, because if we wait to see everything that happens and we 

don’t like the results, it is too late to change it, because these carbon dioxide and other greenhouse gases last in the atmosphere for 

a very long period of time. So that basic approach was taken. The models were selected, as 

we have heard. They are representative of what is in the inter- national community. I just want to emphasize that, as Tony Janetos 

explained, extensive peer review process, comments by Pat Michaels and others were submitted both on the National Assessment and the subsequent climate action report. They were fully 

considered. Responses are fully documented in the public record. You can find those responses on the website of the Global 

Change Research Program. I believe he is going to repeat many of 

those comments today, and it is going to be difficult to sort out all 

of that in this particular forum. I think it is important to recognize 

that those comments were considered, and detailed responses to 

them are available in the public record. So just to make the point that the administration—the current 

administration also accepted these conclusions, it is worth noting 

that in 2001 the Intergovernmental Panel on Climate Change’s 

Synthesis Report of its Third Assessment Report was adopted. The 

State Department submitted detailed comments on the draft of this 

document under this administration, and the administration fully 

participated in a plenary session in September 2001 where the 

summary of policymakers was adopted. I quote extensively—or I quote not extensively, but I quote from 

that report in my written testimony a few examples of the conclusions from that report, which basically show that global warming 

is happening, that we expect to see more heat waves, heavy precipitation events, fewer cold days. These findings were embraced by 

the administration.

Let me focus a little bit more on the U.S. Climate Action Report 

of 2002. This report was based upon conclusions of the National 

Academy of Sciences, the IPCC climate change report that I just 

mentioned, and the National Assessment that we have been discussing today. It was thoroughly vetted by this administration and 

approved before its official release and transmittal to the United 

Nations Framework Convention on Climate Change. Among the key findings of the Climate Action Report are that, 

for example, rather than, ‘‘Rather than simply considering the potential influences of arbitrary changes in temperature, precipitation, and other variables, the use of climate models scenarios ensured that the set of climate conditions considered was internally 

consistent and physically plausible.’’ That is the basic reason for 

using the models. Natural ecosystems appear to be the most vulnerable to climate 

change, because generally little can be done to help them adapt to 

the projected rate and amount of change. Sea level rise at midrange rates is projected to cause additional loss of coastal wetlands,

29

particularly in areas where there are obstructions to landward migration, and put coastal communities at greater risk of storm 

surges, especially in the southeastern United States. Further, it found that reduced snow pack is very likely—and this 

term ‘‘very likely,’’ as Dr. Janetos explained, is a specific term used 

to represent that this is a robust finding—to alter the timing and 

amount of water supplies, potentially exacerbating water shortages, particularly throughout the western United States. Current 

water management practices cannot be successfully altered or 

modified.

So I think the clear conclusion from these findings is that global 

warming does pose a very severe threat to public health and welfare in the United States Let me just finish by summarizing the 

example of a recent study that NRDC and Defenders of Wildlife released in May that used some of the climate models, updated 

versions of two of the models used in the National Assessment plus 

a third model to project the likely effects of global warming on a 

particularly valued sport fish, trout and salmon, in the United 

States.

We found, based on this analysis in this report, which I would 

ask to be included in the record, that at the regional level the loss 

of trout habitat in the northeast and southwest could be particularly severe, although losses are also expected in the southeast and 

Rocky Mountain regions. For example, in Pennsylvania we found that losses of trout habitat are projected to be 6 to 11 percent by 2030, 22 to 28 percent 

by 2060, and 33 to 44 percent by 2090, assuming continued emission increases of heat trapping gases. At the national level the results are loss of 5 to 17 percent by 2030, 14 to 34 percent by 2060. This range of results are based on using a variety of climate 

models to look at the effects that are possible. Providing that range 

is very helpful, because it gives us a sense not of a precise pre- diction but of the likely outcomes and the probability of those outcomes, and gives us a way to really anticipate the types of effects 

we will look at if we don’t take action.

So I believe that climate models are very useful to give a picture 

of what will happen. They are not precise predictions, but they do 

very usefully inform us when we make decisions about whether to 

control emissions of carbon dioxide and other heat trapping gases. 

Though I know it is not the subject of this hearing, I conclude from 

that that it is time to take action, and it is time for mandatory limits on emissions of greenhouse gases. Thank you very much, Mr. Chairman.

[The prepared statement of Daniel A. Lashof follows:]

PREPARED STATEMENT OF DANIEL A. LASHOF, SCIENCE DIRECTOR, CLIMATE CENTER, 

NATURAL RESOURCES DEFENSE COUNCIL

INTRODUCTION

Thank you Mr. Chairman and members of the committee. My name is Daniel 

Lashof, and I am the Science Director of the Natural Resources Defense Council’s 

Climate Center. I appreciate the opportunity to appear before you today. I have been engaged in research and assessment related to global climate change 

for more than 15 years. I was a reviewer of the National Assessment Synthesis Report. I have also served as a Lead Author of the Intergovernmental Panel on Climate Change Special Report Land Use, Land-Use Change, and Forestry and as a

30

reviewer of several reports by the panel. I have also served on the National Research Council’s Committee on Atmospheric Chemistry and on the Energy Research 

and Development Panel of the Presidents’ Committee of Advisers on Science and 

Technology. Previously I served on the Federal Advisory Committee on Options for 

Reducing Greenhouse Gas Emissions from Personal Motor Vehicles. I hold a bachelor’s degree in physics and mathematics from Harvard University and a doctorate 

in Energy and Resources from the University of California at Berkeley. The Natural Resources Defense Council (NRDC) is a national, non-profit organization of scientists, lawyers, and environmental specialists, dedicated to protecting 

public health and the environment. Founded in 1970, NRDC serves more than 

500,000 members from offices in New York, Washington, Los Angeles, and San 

Francisco.

In my statement today I will address the value of using climate models to assess 

the potential effects of global warming on the Untied States and illustrate this by 

reviewing the results of a recent study published by NRDC and Defenders of Wildlife on the threat posed by global warming to trout and salmon.

EXPERIMENTING ON THE EARTH’S CLIMATE

Mr. Chairman, there is only one earth. It is therefore impossible to conduct a controlled physical experiment that compares an ‘‘experimental’’ earth with elevated 

concentrations of carbon dioxide (CO2) and other heat-trapping gases to a ‘‘control’’

earth with an unpolluted atmosphere. Instead we are currently conducting an uncontrolled experiment in which emissions from power plants, automobiles and other 

sources are adding to a thickening layer of carbon pollution in the only atmosphere 

we have. The problem is that if we don’t like the consequences of this experiment 

it will be too late to reverse them.

Given our one-earth experimental design, which I don’t think even Congress has 

the power to change, the best approach available to us is to simulate the earth’s 

climate system using all available data on the composition of the atmosphere, the 

properties of the earth’s surface, and the conditions of the earth’s oceans combined 

with mathematical equations that describe the fundamental physical laws of motion 

and conservation of mass and energy. This is called climate modeling. Climate models allow us to conduct non-destructive controlled experiments: An ‘‘experimental’’

simulation with rising concentrations of heat-trapping gases can be compared to a 

‘‘control’’ simulation with constant concentrations.

The idea of using computers to simulate physical systems with mathematical 

models is not unique to climate modeling. Simulation models are used to test-crash 

cars, test-fly airplanes, and test-detonate nuclear weapons. All without the need to 

sweep up afterward. If computer models were inherently useless, Boeing 777’s 

would be falling out of the skies. In fact, it’s no accident that the Lawrence Livermore National Laboratory does both climate sim- ulations and nuclear weapon simulations. And for the same reason. It is safer to run these tests on computer models 

than on the real thing. Climate models are in fact a remarkable achievement of modern science. Despite 

the incredible complexity of the earth’s climate system, these models are able to 

simulate with high fidelity the major processes that determine the variations in the 

earth’s climate over space and time: from the polar vortex to tropical monsoons and 

from the depths of winter to the heat of summer and everything in between. Are 

the models perfect? Of course not. Someone looking selectively for discrepancies will 

always be able to find something to point to and there will always be room for refinements. Nevertheless, overall the models have achieved a level of realism and accuracy that makes them very useful tools. Indeed, they are the only tool we have 

for safely performing experiments to investigate the effects of large-scale pollution 

of the atmosphere with heat-trapping gases.

THE BUSH ADMINISTRATION RECOGNIZES THE THREAT POSED BY GLOBAL WARMING

The current Bush Administration has recognized the value of using simulation 

models to test the potential consequences of global warming on the United States 

in two recent reports that underwent extensive interagency review. These are the 

2001 Intergovernmental Panel on Climate Change’s (IPCC) Synthesis Report of the 

Third Assessment Report and the U.S. Climate Action Report 2002, formally known 

as the Third National Communication of the United States of America Under the 

United Nations Framework Convention on Climate Change (UNFCCC). First, in August 2001, the State Department submitted detailed comments on the 

draft of the IPCC’s Synthesis Report of the Third Assessment Report. The administration carefully reviewed this report and, while suggesting some changes and clarifications, agreed with all the key findings. Furthermore, they participated fully in

31

the IPCC Plenary meeting in September 2001, where the final IPCC TAR Synthesis 

Report Summary for Policymakers (SPM) was approved in detail. Among other 

things, this report concludes that:

• ‘‘There is new and stronger evidence that most of the warming observed over the 

last 50 years is attributable to human activities.’’ (Climate Change 2001: Synthesis Report, SPM, p. 5) 

• ‘‘Projections using the SRES emissions scenarios in a range of climate models result in an increase in globally averaged surface temperature of 1.4 to 5.8 C over 

the period 1990 to 2100. This is about two to ten times larger than the central 

value of observed warming over the 20th century and the projected rate of 

warming is very likely to be without precedent during at least the last 10,000 

years, based on paleoclimate data.’’ (SPM, p. 8) 

• ‘‘Models project that increasing atmospheric concentrations of greenhouse gases 

result in changes in frequency, intensity, and duration of extreme events, such 

as more hot days, heat waves, heavy precipitation events, and fewer cold days. 

Many of these projected changes would lead to increased risks of floods and 

droughts in many regions, and predominantly adverse impacts on ecological systems, socio-economic sectors, and human health.’’ (SPM, p. 14) 

Then, in May 2002, the administration released the U.S. Climate Action Report 

2002 and submitted it to the Secretariat of the UNFCCC. This report is based upon 

conclusions by the National Academy of Sciences, the IPCC climate change reports, 

and the U.S. Global Change Research Program’s U.S. National Assessment of the 

Potential Consequences of Climate Variability and Change. It was thoroughly vetted 

by this administration and approved before its official release. Among the key finding of the Climate Action Report are:

• ‘‘To provide an objective and quantitative basis for an assessment of the potential 

consequences of climate change, the U.S. National Assessment was organized 

around the use of climate model scenarios that specified changes in the climate 

that might be experienced across the United States (NAST 2001). Rather than 

simply considering the potential influences of arbitrary changes in temperature, 

precipitation, and other variables, the use of climate model scenarios ensured 

that the set of climate conditions considered was internally consistent and physically plausible.’’ (p.84) 

• ‘‘Use of these model results is not meant to imply that they provide accurate predictions of the specific changes in climate that will occur over the next 100 

years. Rather, the models are considered to provide plausible projections of potential changes for the 21st century. For some aspects of climate, all models, 

as well as other lines of evidence, are in agreement on the types of changes to 

be expected. For example, compared to changes during the 20th century, all climate model results suggest that warming during the 21st century across the 

country is very likely to be greater, that sea level and the heat index are going 

to rise more, and that precipitation is more likely to come in the heavier categories experienced in each region.’’ (p.84) 

• ‘‘The model scenarios used in the National Assessment project that the continuing 

growth in greenhouse gas emissions is likely to lead to annual-average warming 

over the United States that could be as much as several degrees Celsius (roughly 3-9°F) during the 21st century. In addition, both precipitation and evaporation are projected to increase, and occurrences of unusual warmth and extreme wet and dry conditions are expectedto become more frequent.’’ (p.84) 

• ‘‘Natural ecosystems appear to be the most vulnerable to climate change because 

generally little can be done to help them adapt to the projected rate and amount 

of change. 

• ‘‘Sea level rise at mid-range rates is projected to cause additional loss of coastal 

wetlands, particularly in areas where there are obstructions to landward migration, and put coastal communities at greater risk of storm surges, especially in 

the southeastern United States. 

• ‘‘Reduced snow-pack is very likely to alter the timing and amount of water supplies, potentially exacerbating water shortages, particularly throughout the 

western United States, if current water management practices cannot be successfully altered or modified. 

• ‘‘Increases in the heat index (which combines temperature and humidity) and in 

the frequency of heat waves are very likely.’’ (p.82). 

The clear conclusion from these findings is that global warming poses a severe 

threat to public health and the environment in the United States. 

32

TROUT AND SALMON IN HOT WATER

A study published by NRDC and Defenders of Wildlife in May on the threat posed 

by global warming to trout and salmon in the United States provides one example 

of the kind of analysis that can be usefully performed using the regional results of 

global climate models. Because trout and salmon are known to be intolerant of 

warm water, their abundance could be threatened if future climate change warms 

the streams they inhabit. I ask that this report be included in the hearing record. 

Trout and salmon are highly valued for their contribution to the economy and culture of the United States. They thrive in the cold, clear streams found in many 

mountainous and northern regions of the country. About 10 million Americans 

spend an average of ten days per year angling in streams or lakes for these fish. 

Dams, water diversions, pollution, and development threaten trout and salmon, 

which have already disappeared from many of the streams where they were formerly found. Global warming poses a less visible but no less severe threat to their 

survival. 

To assess the magnitude of this threat we contracted with Abt Associates to perform a new simulation study of how climate change might affect existing habitat 

for four species of trout (brook, cutthroat, rainbow, and brown) and four species of 

salmon (chum, pink, coho and chinook) in streams throughout the contiguous United 

States. The simulation uses the results of three different climate models, including 

updated versions of the Canadian model (CGCM2) and the Hadley Center model 

(HadCm3) used in the National Assessment, as well as an Australian model 

(CSIRO-Mk2). The changes in air temperatures projected by these global climate 

models are used to project the impact of global warming on U.S. stream temperatures, using a new, more accurate method to estimate the relationship between air 

and stream temperatures. 

Interestingly, the version of the Hadley Center model used for this study projects 

warming rates for the United States that are quite similar to Canadian Model results used in the National Assessment. Trout and salmon are particularly sensitive 

to increases in summer temperature and the Hadley Model (HadCm3) projects an 

increase in average July temperatures for the contiguous United States of as much 

as 10 degrees Fahrenheit by 2090, assuming that emissions of heat-trapping gases 

are not curtailed. 

The study found that trout and salmon habitat is indeed vulnerable to the effects 

of global warming. At the national level we estimate that individual species of trout 

and salmon could lose 5-17 percent of their existing habitat by the year 2030, 14-

34 percent by 2060, and 21-42 percent by 2090, based on emissions scenarios A1 

and A2 from the Intergovernmental Panel on Climate Change (IPCC), depending on 

the species considered and model used. Projected effects on trout and salmon are 

lower for IPCC scenarios B1 and B2, which assume that global CO2 emissions are 

reduced for reasons not directly related to global warming. For these scenarios, we 

estimate habitat losses of 4-20 percent by 2030, 7-31 percent by 2060, and 14-36 

percent by 2090, depending on fish species and model. Of particular concern is the 

number of stream locations that become unsuitable for all modeled species (Exhibit 

1). 

At the regional level, loss of trout habitat in the Northeast and the Southwest 

could be particularly severe, although losses are also expected in the Southeast and 

Rocky Mountain regions. For example, in Pennsylvania losses of trout habitat are 

projected to be 6-11 percent by 2030, 22-28 percent by 2060, and 33-44 percent by 

2090, based on the A1 and A2 emission scenarios. Significant losses of salmon habitat are projected throughout their current range. The number of locations expected 

to become unsuitable for both trout and salmon expands steadily over time, assuming emissions of heat-trapping gases continue to increase (Exhibit 2). 

These results are robust with respect to key model specifications and assumptions. For a given emissions scenario, the greatest uncertainty is due to differences 

among the global climate models, yet the results provide a valuable indicator of the 

regions most vulnerable to loss of cold water fish habitat. Differences among the scenarios for future emissions of heat-trapping gases also significantly affect the results, even though none of the scenarios examined assumes that policies are adopted 

specifically to address global warming. For all emissions scenarios our results are 

likely to understate expected losses of habitat because of the several dimensions of 

climate change and potential effects on habitat that were beyond the scope of the 

study. These include potential effects on stream flows, changes to the temperature 

of groundwater discharge, changes in ocean conditions, and other considerations. In 

addition, these results must be viewed within the context of other present and future threats to fish habitat, which are likely to add to the temperature-related 

losses estimated in the report. 

33

This analysis demonstrates that it is possible to draw robust conclusions about 

the vulnerability of key resources to the effects of global warming, despite variations 

in climate model projections. The results show that future strategies to protect trout 

and salmon will need to address the potential effects of global warming. 

RESPONDING TO THE THREAT OF GLOBAL WARMING

The administration has recognized the threat posed to the United States by global 

warming and has reaffirmed the United States’ commitment to the objective of the 

Framework Convention on Climate Change, which is to stabilize greenhouse gas 

concentrations in the atmosphere at safe levels. Nonetheless, the administration has 

refused to consider any mandatory limits on emissions of heat-trapping gases. This 

position is both illogical and irresponsible. 

The administration has argued, in essence, that mandatory limits on emissions 

of CO2 and other heat-trapping gases would harm the economy, and that therefore 

we should rely on voluntary measures and adapt to changes in climate. The administration has not advanced any analysis, however, to suggest that voluntary action 

has any chance of stabilizing greenhouse gas concentrations in the atmosphere. Indeed, the United States has now relied on voluntary measures for more than a decade and emissions have continued to increase. 

The administration’s claim that setting mandatory limits on emissions now would 

harm the economy is equally unsupported by analysis. While it is possible to construct straw-man proposals that would be costly, surely there must be some level 

and timetable for a CO2 emission limit that would be affordable. Yet the administration has rejected any mandatory limit out of hand. In fact, failure to set limits now 

will lead to stranded investments in new highly emitting power plants and other 

equipment that will become obsolete when limits are established in the future. 

Further delay in establishing mandatory limits on heat-trapping gas emissions is 

irresponsible because our window for taking action in time to stabilize greenhouse 

gas concentrations at safe levels is rapidly closing. The IPCC Synthesis Report cited 

earlier, which was adopted with the full participation of the administration, makes 

this quite clear:

• ‘‘The severity of the adverse impacts will be larger for greater cumulative emissions of greenhouse gases and associated changes in climate.’’ (SPM p.9) 

• ‘‘Inertia is a widespread inherent characteristic of the interacting climate, ecological, and socieconomic systems. Thus some impacts of anthropogenic climate 

change may be slow to become apparent, and some could be irreversible if climate change is not limited in both rate and magnitude before associated thresholds, whose positions may be poorly known, are crossed.’’ (SPM p. 16) 

• ‘‘The pervasiveness of inertia and the possibility of irreversibility in the interacting climate, ecological, and socio-economic systems are major reasons why 

anticipatory adaptation and mitigation actions are beneficial. A number of opportunities to exercise adaptation and mitigation options may be lost if action 

is delayed.’’ (SPM p. 18) 

Mr. Chairman, global warming poses a clear threat to the United States. The good 

news is that this is a threat that we know how to stop. Now is the time to set mandatory limits on emissions of heat-trapping gases. 

Thank you.

34

Mr. GREENWOOD. Thank you, Dr. Lashof. The last two times at 

my trout fishing in Pennsylvania I caught nothing. Now I know 

why. 

Dr. O’Brien. 

TESTIMONY OF JAMES J. O’BRIEN 

Mr. O’BRIEN. Mr. Chairman, thank you very much for inviting 

me today. I have been a physical scientist in oceanography/meteorology for 40 years. I will tell you that in the early part of my career 

primarily I was an ocean modeler, and my students and I are recognized for that internationally. Then in the Seventies, late Seventies and Eighties, we contributed to understanding of El Nino and 

how it can be forecast, and then in the Nineties, while most scientists were studying what was happening in tropical countries, 

my students and I concentrated on impacts in the United States, 

and I have listed in my paper many of the things we have done. 

In 1990 I accepted the pro bono job as the State Climatologist in 

Florida. Mr. Deutsch, I am your State Climatologist. So if you have 

any constituents who need to know about climate variability or climate data, please refer them to my office in Tallahassee. 

The reason I took it was very simple. Based on the climate variability studies, which is part of my theme, the mitigatable impact 

in the State of Florida is at least $500 million a year, primarily in 

forestry and agriculture, tourism and fisheries. I want to see that 

we accelerate this information for the people of Florida. 

Recently, we have actually developed—which is now being used 

by the wildfire management people in Florida—a way to predict up 

to 6 months in advance which county is more vulnerable for forest 

fires. You know we have had quite a time with 3 years of drought 

in the State of Florida. 

So we provide climate advice to the citizens of Florida for all sectors, but particularly agricultural, forestry, tourism and power generation, and I am funded by NOAA in this area also to do the reVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00038 Fmt 6633 Sfmt 6602 W:\DISC\81495 81495

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35

search that goes along with providing the information. We work 

closely with Tom Karl and he provides us lots of the old data which 

is very useful. 

Now, turning to the National Regional Assessment of Climate 

Change, I was the co-chair for the Southeast Regional Assessment. 

Unfortunately, my co-chair, Dr. Ron Ritschard, died at an early 

year. We were funded by NASA. 

Today I want to focus on the question, and in my scientific opinion, the Hadley model is a state-of-the-art model, but it has poor 

horizontal resolution, inadequate physics, particularly in the ocean 

component. And since we deal primarily with—when we worry 

about whether it is going to be a cold winter in Chicago, you know, 

or too much rain in San Diego, these are related to what the ocean 

is doing, the memory that the ocean has, and it is very important 

if you are going to do a 100 year run that you have an adequate 

ocean model. 

A very prominent French physical oceanographer told me recently—fortunately, he is quite young—that he hopes that before 

he dies, the ocean models used by these global climate models represents something that he knows that’s in the real ocean. 

Anyway, my opinion is that to Canadian model is very flawed 

and should never have been used. Even when it was first distributed to the team across the United States, the data was represented incorrectly geographically, and the attitude was, well, 

maybe that is not real important. I have no knowledge whether 

they actually ever fixed it up. 

You know, I enjoy learning about climate variability over the 

United States, such as floods, droughts, freezes, and hurricanes. I 

don’t have time to go into what our studies have shown us, but for 

the average citizen, you know, they are wondering about the variability in climate. Okay? Is it different than, you know, my grandfather told me about? Is my experience different? 

They are not really interested in whether the average temperature is going to rise 3 to 5 degrees Fahrenheit in 100 years. They 

are interested in is winter going to be colder than normal and 

many other things. 

For example, one of the things I discovered early on the Canadian model is they didn’t have El Ninos in it. Now I was told it 

is in there, but I have looked at the data. I am an expert in that, 

and I couldn’t find any sign of it, and I cannot imagine any climate 

model that we are going to run for 100 years that doesn’t have 

some robust signal of the way that our climate variability is changing on year to year and decadals. 

In the Hadley model, you see that, but you don’t see that in the 

Canadian model. We are three State climatologists here today, and 

another one from the State of Alabama, Dr. John Christie, says 

that he believes that the Canadian model was modeling another 

planet than this one. 

Okay. Can we do better? I think we can really do better, and I 

actually have some very good news. Yesterday when I came, someone delivered to me a testimony of James Mahoney, who is now the 

Assistant Secretary of Commerce for Ocean Atmospheres, and he 

on July 11 this year before the Committee on Commerce, Science 

36

and Transportation of the U.S. Senate had delivered this paper 

which I can add into the record. 

In just part of it he says that uncertainties in climate models address exactly what we are talking about. It says the poor regional 

performance of current general circular models severely restricts 

the examination of potential global climate influence on key regional systems. I am so delighted that at very high level in government that that is now understood. 

I am going to conclude now and just say that I believe global climate change would occur. I am not convinced that we are going to 

see it in terms of surface temperature increase or sea level increase. It will change. We need to address what to do. 

In my outline I have indicated that we need a new Manhattan 

type project. We need an institute outside the government, labs in 

the government, where we hire the best managers,the best scientists, and give them finally decent computers so they can do the 

job correctly and make adequate American models. 

There is a model like this, sir. The model is the European Centre 

model for medium range weather prediction where the European 

nations got together and formed a center which is physically in 

Britain but has members all over. I think nobody will disagree in 

this room that they give the best week-long weather forecasts of 

anyplace. The reason they do is because of a unique way it is managed—good managers that don’t stay there for lifetimes, good scientists that stay 5 to 10 years and then go to their home countries, 

and the best computers in the world for doing the problem right. 

The technical director of the Center for European Centre for Medium Weather Prediction, a good Irishman like me, recently said 

to General Kelly, the head of the Weather Service—He says, General Kelly, we are two decades ahead of you now; why don’t you 

just buy our results and shut down the operation. 

Thank you very much. 

[The prepared statement of James J. O’Brien follows:]

PREPARED STATEMENT OF JAMES J. O’BRIEN, ROBERT O. LAWTON DISTINGUISHED

PROFESSOR, METEOROLOGY AND OCEANOGRAPHY, THE FLORIDA STATE UNIVERSITY

INTRODUCTION

I have been a physical scientist in oceanography and meteorology for 40 years. 

In my early years, my graduate students and postdocs concentrated primarily on 

modeling time dependent ocean motions. In the late 1970’s and 1980’s, we contributed to the physical understanding of El Nino. Namely, how it works and how it 

can be forecast. 

In the 1990’s, while most other scientists were applying ENSO forecasts to tropical countries, my students and I have concentrated on impacts in the United 

States. We have written papers on: ENSO and Atlantic Hurricanes; ENSO and Tornadoes; ENSO and Precipitation; ENSO and Temperature; ENSO and Wild Fires (In 

Florida); ENSO and Snowfall; ENSO and Excessive Wind Events; ENSO and Great 

Lakes Snow Events; and ENSO and Freezes in Central Florida. 

In 1999, I accepted the pro bono job as official State of Florida Climatologist. We 

have been advising the Florida Commissioner of Agriculture on wild fire forecasts, 

droughts, hurricanes, etc. We provide climate advice to the citizens of Florida for 

all sectors, but, particularly agriculture, forestry, fisheries, tourism and power generation. 

In some local circles, I am labeled, Dr. El Nino for my research. 

Turning now to the National Regional Assessment of Climate Change, I was the 

Co-Chair for the Southeast Regional Assessment. (My Co-Chair, Dr. Ron Ritschard, 

recently died at a young age). Our work was funded by NASA, Huntsville, Alabama. 

37

In the early beginnings of the National Regional Assessment, the entire U.S. team 

met and we agreed there would be ‘‘ONE’’ Global CO2 doubling model so everyone 

referring to future projections would be on the same page. There were two choices: 

(1) The Hadley, (British model), or (2) The Max Planck (German model). The Hadley 

model was selected. Subsequently, I attended a meeting of the U.S. National Resource Board Committee on Climate. Many senior scientists were shocked that there 

was no American models. In due time, a very new recent model, the Canadian 

Model was added for our use. It was recently computed so no documentation or response of this model was available to the assessment teams. 

In my opinion, the Hadley model is a state-of-the-art model with poor resolution, 

inadequate physics—particularly, the ocean component. The Hadley Model gives 

reasonable projections, but it is still flawed and I am sure that, in due time, will 

be improved. As better ocean models are improved in climate models, the future 

changes are greatly reduced. 

The Canadian’s model is flawed, and, in my opinion, should never have been used. 

My effort to capture the attention of the leaders to recognize this were rejected outright. My team discovered that, initially, the data provided to the team had been 

incorrectly registered with respect to the geography of the U.S. Since the model has 

horizontal grid boxes around 500 km on a side, being set off by one grid, really confuses geographic identification. (As an aside, I do not know if this was fixed, but 

I was told it can’t make any difference). 

I really enjoy learning about climate variability over the United States, such as 

droughts, floods, freezes, hurricanes, etc. For the citizen for whom climate is important, it is the variability which matters! It is not whether the average temperature 

will rise 3-5 °F in 100 years. The citizen wants to know ‘‘Is this winter going to be 

colder than normal?’’ and other simple questions. I discovered that we could not find 

ENSO variability in the ocean model of the Canadian model. I was told it was there, 

but it makes no difference if it is too small. 

Mr. Chairman, the variability of climate over most of the United States is primarily controlled by ENSO and other ocean-related phenomena (North Atlantic Oscillation, and the Pacific Decadal Oscillation) and land use changes. I cannot accept 

a 100 year climate run as useful if it doesn’t also include the observed variability 

in the climate system. 

What is the climate system? It is the entire atmosphere, ocean, land, ice systems 

which are heated by the sun. The chemistry of global climate change is completely 

correct. We have an excellent scientific understanding of how radiatively-active 

gases such as carbon dioxide, methane and water vapor can delay heat in the climate system. There is an assumption that this extra heat will manifest itself in 

raising the temperature of the biosphere—that portion of the climate system in 

which we humans live. The data measured from the actual climate system seems 

to indicate other processes are dominate, such as stronger mid-latitude storms 

which are important for distributing the extra heat. In my opinion, even the current 

models are not capable in calculating the climate system well enough for policymakers to believe in any projection. 

Can we do it better? I believe we can, but it will take a new effort and considerable investment. We know most of the physics of the climate system. In order to 

calculate the variability of the system, we need adequate computers. We need the 

kind of investment in computers that the Congress funds to DOD, NSF, NSA, etc. 

I propose a ‘‘Manhattan Type Project’’ to estimate future climate variability for 

our National Security. Any future climate change will probably require trillions of 

dollars to adjust our culture or mitigate the consequences. My vision is a NEW Institute, outside the government with top management, the best scientists and adequate resources. My estimate is $50M/year for at least 10 years. 

When I suggest this, OMB folks usually ask me, ‘‘Dr. O’Brien, where are we going 

to find that money?’’ My answer is, ‘‘Give us 2 attack helicopters’’ monies, and we 

will be happy for a few years. Give us a fighter jet monies, we will be very happy 

for a few years. Give us an aircraft carrier monies, and we will never ask for any 

more resources’’. The Congress has to decide on the priorities. Do we want to understand the future climate or not? 

Returning to my belief, that we can do better in modeling climate, I am encouraged that each generation of climate change modeling gets better. The original CO2-

doubling model by NASS,GISS under the leadership of Dr. Jim Hansen, estimated 

around 10 °F surface temperature change by 2050. This was so dramatic because no 

ocean was included. I remember reading in the Tallahassee Democrat, a story that 

said, as a result of the GISS model, that sea-level would rise 3 meters or 7-10 feet 

by 2050. The current IPCC estimates a few degrees temperature rise by 2100 and 

a doubling of the current sea-level rise of around 8-10 inches to 20 inches as the 

38

worst case by 2100. Certainly, policymakers will react differently to plan for a two 

feet rise in 100 years vs. 10 feet rise in a generation. 

Let me provide one more remark on sealevel rise. In order to double sealevel, one 

would expect to observe an increased rate of rise by 2002. Everyone agrees that the 

current average rise is about 7-10 inches a century, averaged over the globe. However, the experts who have tried to find any acceleration find none. 

How about global warming in the United States? I will leave this subject to my 

fellow climatologist, Dr. Tom Karl. I am, however, the State Climatologist of Florida. In Florida, the cities are warming at the rate of about one degree in the entire 

20th century. But the rural places are cooling at the rate of more than one degree 

per century. I have included some graphics in my presentation documenting this for 

minimum temperature over the entire 20th Century. What is happening? My fellow, 

State Climatologist, from Colorado, Dr. Roger Pielke, Sr., explains this by land use 

changes. Dr. Karl has published work showing the cooling in the Southeast United 

States, but unfortunately, the summary of average temperature in Florida in the 

last century, in the S.E. Assessment summary, shows Florida warmer than the 

rural data would dictate. 

Finally, the ocean part of the global climate system models are very inadequate. 

The research community is aware that warm and cold ocean currents are very important in predicting the weather even for 10 days. It is critical to model the oceans 

correctly if a global climate model is expected to work at all. A young French ocean 

modeler said to me recently, ‘‘I hope that the ocean models used by global climate 

models look like the real ocean before I die!’’

There are hundreds of scientists other than climate modelers that have been told 

the Hadley and Canadian models are good projections of the future. This is a shame. 

When I joined the U.S. National Assessment Team as Co-Chair of the Southeast Regional Assessment, a bright young EPA ecologist from Louisiana reported to me that 

the number of hurricanes in the Gulf of Mexico were increasing due to global warming. I was unaware of this. Consequently, my students and I did a study. We found, 

that, in fact, the number of hurricanes have decreased significantly in the Gulf of 

Mexico. This is a published paper. 1998: Are Gulf Hurricanes Getting Stronger? 

Bull. Amer. Meteorol. Soc., 79(7), pp. 1327-1328 (with Bove, M.C., and D. F. 

Zierden). 

CONCLUSION

Global climate changes will occur. Whether surface temperatures will increase 

due to radiatively-active emissions is not clear. The Global Climate System must 

change. In order to address what the nation needs to do, I recommend a large investment in improving the basic understanding by investing in very good global climate system calculations.

39


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Mr. GREENWOOD. Thank you. My staff said it sounds like a field 

hearing. We will have to go over to Europe and take a look at that. 

Dr. Pielke. 

TESTIMONY OF ROGER A. PIELKE, SR. 

Mr. PIELKE. Yes, Mr. Chairman, members of the committee, 

thank you for the opportunity to present testimony. I received my 

PhD and Master’s degree from Penn State in the Department of 

Meteorology, and since the 1960’s my research has focused on 

weather and climate studies using both models and observations. 

In my testimony I would like to convey two main points: First, 

that the perspective I am presenting today does not easily fit into 

the conventional two-sided debate over climate change. This third 

perspective, as I have written elsewhere, suggests that humans 

have an even greater impact on climate than is suggested by the 

international and national assessments. 

The human influence on climate is significant and multi-faceted. 

However, any attempt to accurately predict future climate is fundamentally constrained by the significant and multi-faceted characteristics of the human influence on climate. By focusing on 

vulnerabilities rather than prediction as a focus of research, I believe that the scientific community can provide more comprehensive and likely more useful information to decisionmakers. 

These points are consistent with the American Association of 

State Climatologists Policy Statement on Climate Variability and 

Change which was approved on October 25, 2001, and I will read 

part of that statement: ‘‘Our statement provides the perspective of our Society on issues 

of climate variability and change. Since the Society members work 

directly with users of climate information at the local, State and regional levels, it is uniquely able to put global climate issues into 

the local perspective which are needed by users of climate information. Our main conclusions are as follows: ‘‘First, past climate is a useful guide to the future. Assessing past 

climate conditions provides a very effective analysis tool to assess 

societal and environmental vulnerability to future climate, regardless of the extent the future climate is altered by human activity. 

Our current and future vulnerability, however, will be different 

than in the past, even if the climate were not to change, because 

society and the environment change as well. Decision makers need 

assessments of how climate vulnerability has changed. 

‘‘Two, climate prediction is complex with many uncertainties. The 

AASC recognizes climate prediction is an extremely difficult undertaking. For time scales of a decade or more, understanding the empirical accuracy of such predictions, called verification, is simply 

impossible, since we have to wait a decade or longer to assess the 

accuracy of the forecasts.’’

In the remainder of my 5 minutes I will discuss one example of 

the scientific basis that underlie the statement. Greater detail is 

available in the peer reviewed scientific publications that are listed 

at the end of my written testimony. 

A fundamental basis of the U.S. National Assessment is the use 

of the Canadian and Hadley Centre General Circulation Models to 

project the future state of the climate as the basis for discussion 

43

of climate impacts and ultimately alternative courses of action by 

decisionmakers. The perspective I offer here suggests that in relying on GCMs to, in effect, bound the future state of the climate, 

the U.S. National Assessment may have had the effect of underestimating the potential for change and overestimating our ability 

to accurately characterize such changes with computer models. 

The hypothesis for using these models is that including human 

caused increases of carbon dioxide and other greenhouse gases and 

aerosols in the models are sufficient to predict long term effects on 

the climate of the United States. The position presented here is 

that such forcings are important, but a subset of those needed to 

develop plausible projections, and even if all the forcings were included, accurate long term prediction would remain challenging, if 

not impossible. 

To test the hypothesis that GCMs can accurately project climate, 

it is possible to compare model performances with observed data 

for the period 1979-2000. One test is the ability of the model to predict the averaged temperatures of the earth’s atmosphere over this 

20-year period. Such a test is a necessary condition for regional 

projection skill, since if globally averaged long term changes cannot 

be skillfully projected, there will necessarily be no regional skill. 

During this period, for example, at around 18,000 feet above sea 

level, the Canadian GCM projects a 0.7 degree C warming of the 

global averaged temperature. The Hadley Centre model also has 

atmosphere warming for this time period. The observations, in contrast, have no statistically significant change in these averaged atmospheric temperatures. 

Thus, either the models or the observations must be incorrect. 

Both cannot be correct. Since, for the 1979-2000 time period, satellite, radiosonde and National Center for Environmental Prediction model reanalyses each agree closely with respect to global 

averages, the observations should be interpreted as our best estimate of reality. 

The scientific evidence, therefore, is that the models have failed 

to replicate the actual evolution of atmospheric temperatures over 

the time period 1979-2000. Thus using the results of these models 

as the basis for assessments, much less for particular decisions, for 

the next several decades is not justified. Such models clearly have 

usefulness as scientific tools with which to conduct sensitivity experiments, but it is important to not overstate their capabilities as 

predictive tools. 

One major reason for this difficulty is the absence and/or inadequate representation of significant human caused forcing of the 

climate. These include land use changes over time, the effect of 

aerosols on clouds and precipitation, and the biogeochemical effect 

of carbon dioxide. The Intergovernmental Panel on Climate itself 

concludes that there is a very low level of scientific understanding 

of these forcings. 

The importance of one of these effects can be illustrated by a just 

published paper of the influence of human caused land use change 

on the global climate. Even with a conservative estimate of land 

use change, the global redistribution of heat and the effects on regional climate is at least as large as simulated by the existing 

GCM simulations. However, even when these forcings are included, 

44

the complex interactions among the components of the climate system will likely limit our ability to skillfully predict the future. Indeed, we cannot even predict with any skill beyond a season in advance, and then only under special situations such as an evolving 

El Nino. 

As a result, we have—There is a new book that is coming out by 

the International Geosphere-Biosphere Programme titled ‘‘Vegetation, Water, Humans and the Climate,’’ and there is a chapter in 

there which talks about how to evaluate the vulnerability in changing environmental conditions. 

This chapter basically proposes that we start first from an assessment of vulnerability. Only at that point do we bring in these 

other tools, such as GCM models, historical record, and so forth. 

Even the IPCC, I am told by some colleagues, is starting to embrace a greater focus on vulnerability, and several U.S. programs, 

most notably the Regional Integrated Science and Assessments program of NOAA, have also acknowledge the importance of vulnerability as a scientific organizing theme. 

Let me conclude by saying I wish to underscore that the inability 

of the U.S. National Assessment models to skillfully predict climate 

change does not mean that the radiative effect of anthropogenic 

greenhouse gases on climate is not important, nor does it suggest 

which policy responses to the issues of climate change make the 

most sense. 

Such matters of policy go well beyond any discussion of the 

issues of science and well beyond the information presented in my 

testimony today. 

Effective mitigation and adaptation policies in the context of climate variability and change do not depend on accurate prediction 

of the future and, consequently, a lack of ability to generate accurate predictions should not be used as a justification to ignore the 

policy challenges presented by climate. Too often, debate over climate substitutes for debate over policy. 

Thank you. 

[The prepared statement of Roger A. Pielke, Sr. follows:]


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Mr. GREENWOOD. Thank you, Dr. Pielke. 

Dr. Michaels. 

TESTIMONY OF PATRICK J. MICHAELS 

Mr. MICHAELS. Mr. Chairman, I am sitting over here. Dr. 

O’Brien is much more handsome. 

I am a Professor of Environmental Sciences at the University of 

Virginia and past President of the American Association of State 

Climatologists, and I should say my colleague, Roger, is the future 

President. 

I offer you a word of caution on the science about which we base 

our Nation’s policy on global warming. Mr. Chairman, would you 

tell people what was going to happen to the United States temperature based upon a table of random numbers? I don’t think so. But 

that is what happened in the assessment on climate change. 

Effects have causes. Our society is currently confronting a potentially serious effect, the specter of climate change caused by human 

alteration of the atmosphere. We ask scientists to quantify these 

causes and effects. They pursue truth by making hypotheses and 

testing them against reality. In climate science, these hypotheses


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are computer models. If they are at odds with reality, they only inform bad policy. 

It is absolutely logical to want a scientific assessment of the effect of human induced climate variability on the U.S. Coming from 

the University of Virginia, I am commanded, as you know, to refer 

to its founder, Thomas Jefferson. Had he been alive and seen 

changes in the greenhouse effect that we have observed today, he 

would ask scientists what will happen to America’s climate? 

So let’s transport Mr. Jefferson’s scientists in the 19th Century, 

newly minted in the environment, naive, not involved in the political process. What would they do? Well, they would probably learn 

about computer models such as we have today, and then they 

would use those computer models to drive impact of climate change 

on other aspects of our society, our farms, our forests, our water 

supply. 

That is, in a sense, what was used for the methodology for the 

U.S. National Assessment on Climate Change. Now what models 

would they choose? I argue they would find a climate model that 

predicted large changes, one that predicted medium changes, and 

probably a third that predicted small changes. 

In the very real case of the 20th Century National Assessment 

on Climate Change, two models were chosen. The first from the Canadian Climate Center, shown here in this Vu-Graph, predicts the 

largest changes of temperature of any of the models considered 

here in the report. 

It is also different than the dozens of other climate models. It is 

against the consensus of climate models, as described by the 

United Nations, because it has an exponential increase in temperature, meaning an increase which gets larger and larger in terms of 

rate, as opposed to the average of models. This is from the United 

Nations’ new summary on climate change, which you can see clearly is a straight line. 

So not only have we chosen the most extreme temperature prediction, we have chosen one whose mathematical and functional 

form is at variance to the consensus of models. 

The second model used in the Assessment, from Britain’s Hadley 

Center, predicts the largest changes in rainfall. These are the precipitation forecasts from the models considered. You can see this is 

at major variance to any of the other consensus models that we 

have. 

Consequently, the very real 20th Century scientists, as opposed 

to our 19th Century hypothetical scientists, chose the most extreme 

forecasts to guide our national assessment. I would bet our 19th 

Century scientists would ask another question: Do these models 

work? And they would test them, and they would discover that 

both the Hadley and the Canadian models chosen by the 20th Century counterparts were worse than a table of random numbers 

when applied to United States temperatures. 

At this point, I believe the 19th Century scientists would have 

stopped and said we do not have the tools to forward project climate. They might have said, perhaps we should take a look at how 

U.S. climate has changed as the greenhouse effect has changed and 

as global temperatures have changed. 

52

The very real 20th Century assessment teams was informed in 

the review process about this problem with the models. IN public 

comments, it was swept aside with a statement that United States 

temperatures are warming, model temperatures are warming and, 

therefore, everything is fine. 

In fact, the Canadian model predicts recent years to be 2.7 degrees warmer than the years in which the Canadian model starts. 

The observed change in U.S. temperature is .9 degrees, a 300 percent error. 

Random numbers are not plausible scenarios. It is no longer 

science when our results are worse than random numbers. It is 

mathematical philosophy. It is scenario building, but it is not 

science. Mr. Chairman, whatever is based upon models that do not 

better than random numbers is science fiction, glossy, colorful, meticulous, but fiction. 

Unfortunately, the assessment serves as the basis for sweeping 

legislation on global warming at both the Federal and the State 

levels. Using computer models that demonstrably do not work can 

only inform bad policy. 

The first time I testified on the subject of global warming was 

in February 1889—yes, it seems like 1889—1989 before this very 

Energy and Commerce committee. I stated then that warming was 

likely to be at the lowest end of projected ranges based on a comparison of then existing models and observed temperatures. I stated that ‘‘our policy should be commensurate with our science.’’ Thirteen years later I am compelled to tell you exactly the same. 

Thank you. 

[The prepared statement of Patrick J. Michaels follows:]

PREPARED STATEMENT OF PATRICK J. MICHAELS, DEPARTMENT OF ENVIRONMENTAL

SCIENCES, UNIVERSITY OF VIRGINIA

This testimony makes no official representation for the University of Virginia or 

the Commonwealth of Virginia, and is tendered under the traditional protections of 

academic freedom. 

Effects have causes. Confronting our society today is a potentially serious effect, 

climate change, caused by human influence on our global atmosphere. 

The quantitative tools of mathematics and science are what we use to inform rational analysis of cause and effect. Science, in particular, obeys a rigid standard: 

that the tools we use must be realistic and must conform to observed reality. If they 

do not, we modify or abandon them in search of other analytical methods. Whenever 

the federal government releases a comprehensive science report, the public naturally assumes that it has passed these tests. The documents we will discuss today 

failed those tests. This failure was ignored in the public review process. 

There is no doubt that the issue of climate change rightly provokes private citizens and our government to ask what its potential effects might be on the United 

States. That was the purpose of the recent report Climate Change Impacts on the 

United States: The Potential Consequences of Climate Variability and Change. This 

document is often called the ‘‘U.S. National Assessment’’ (USNA) of climate change. 

This report forms much of the basis for Chapter 6 of the U.S. Climate Action Report—2002, a chapter on ‘‘Impacts and Adaptation’’ to climate change. 

The USNA began with a communication from President Clinton’s National 

Science and Technology Council (NSTC), which was established in 1993. According 

to the USNA, ‘‘This cabinet-level council is the principal means for the President 

to coordinate science, space and technology policies across the Federal Government.’’

‘‘Membership consists of the Vice President [Al Gore], the Assistant to the President 

for Science and Technology, Cabinet Secretaries and Agency heads...’’ The Council 

is clearly a political body (‘‘coordinating... policies’’) rather than a scientific one. 

This NSTC was, in turn, composed of several committees, including the Committee on Environment and Natural Resources, chaired in 1998 by two political appointees, D. James Baker and Rosina Bierbaum. Baker developed a further subVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00056 Fmt 6633 Sfmt 6621 W:\DISC\81495 81495
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1 In 1998, the National Research Council report Capacity of U.S. Climate Modeling to Support 

Climate Change Assessment Activities strongly remonstrated against the use of foreign models 

to assess U.S. climate. According to the NRC, ‘‘. . . it is inappropriate for the United States to 

rely heavily upon foreign centers to provide high-end modeling capabilities. There are a number 

of reasons for this including...[the fact that] decisions that might substantially affect the U.S. 

economy might be based upon considerations of simulations... produced by countries with different priorities than those of the United States.’’

committee of his committee, the Subcommittee on Global Change Research, to ‘‘provide for the development . . . of a comprehensive and integrated... program which 

will assist the Nation and the world to understand, assess, predict [emphasis 

added], and respond to human-induced and natural processes of global change.’’ Ultimately, this resulted in the selection of the National Assessment Synthesis Team 

(NAST). 

NAST was confronted with a daunting task, detailed in the schematic below. The 

chain of cause and effect begins with industrial activity and the combustion of compounds that alter the atmosphere’s radiative balance. These are then distributed 

through the atmosphere. These affect the climate of the United States. Then, those 

changes in climate are input to a subsidiary series of computer models for forest 

growth, agriculture, etc.

An understanding of the effects of climate change on the United States requires 

that there be no substantially weak links in this catena. As an example of a relatively strong link, I would estimate that we understand about 70 percent of the 

changes in atmospheric carbon dioxide that result from human activity. The reason 

this number is not 100 percent largely stems from the fact that the current concentration of carbon dioxide seems low, given the amount emitted and assumptions 

about how it distributes through the atmosphere and the biosphere, and how it 

eventually returns to the soil and the ocean bottom. 

There are two main ways to assess the most important of these linkages, which 

is between ‘‘Atmospheric Changes’’ and ‘‘Climate Changes in the United States.’’

One involves the use of computer simulations, known as General Circulation Models 

(GCMs) to estimate how climate changes as a result of atmospheric alterations. An 

alternative method for assessment is described on page 10 of this Testimony. 

There are literally dozens of GCMs currently available, and the USNA considered 

a subgroup of these models. Eventually, they selected two, the Canadian Climate 

Centre model, acronymed CGCM1, and another from the United Kingdom Meteorological Office, known as HadCM2 1. The prime outputs of these models that are important for the assessment of climate change are temperature and precipitation. 

In using GCMs to project future climate at regional scales, the USNA clearly 

placed itself squarely against the consensus of world climate science. In 2001, the 

United Nations’ Intergovernmental Panel on Climate Change (IPCC) compendium 

on climate change, the Third Assessment Report, states: 

‘‘Despite recent improvements and developments . . . a coherent picture of regional climate change... cannot yet be drawn. More co-ordinated efforts are


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thus necessary to improve the integrated hierarchy of models... and apply these 

methods to climate change research in a comprehensive strategy.’’ In other words, even three years after the Assessment team began its report relying on GCMs, the consensus of world climate science was that they were inappropriate for regional estimates, such as those required for the United States.

CHOICE OF EXTREME MODELS

As shown in the IPCC’s Third Assessment Report of climate change, the average 

behavior of GCMs is to produce a linear (constant) rate of warming over the projectable future. In other words, once warming begins from human influence, it takes 

place at a constant, rather than an exponentially increasing rate. However, the CGCM1 is an outlier among the consensus of models, producing a 

warming that increases as a substantial exponent. This behavior can be seen in Figure 1a, taken directly from the USNA, in which the CGCM1 clearly projects more 

warming than the others illustrated in the USNA. The USNA also illustrates a similarly disturbing behavior for precipitation. Figure 

1b, again taken directly from the USNA, shows that the other model employed, 

HadCM2, predicts larger precipitation changes than the others that are illustrated 

in the USNA.

A close inspection of Figure 1a reveals that CGCM1 predicts that the temperatures in the United States at the end of the 20th century should be about 2.7 °F 

warmer than they were at the beginning, but the observed warming during this 

time, according to the most recent analysis from the National Climatic Data Center, 

is 0.9 °F. CGCM1 is making a 300 percent error in its estimation of U.S. temperature changes in the last 100 years. My colleague Thomas Karl, Director of the National Climatic Data Center and cochair of the USNA synthesis, explained that the reason CGCM1 was chosen was because it was one of only two models (the other was HadCM2) that produced daily 

temperature output, and that this was required to drive some of the subsidiary models, such as those for forest impacts. Michael MacCracken, Executive Director of the National Assessment Coordination 

Office, told me otherwise. He said that the two models were selected because they 

gave extreme results, and that this was a useful exercise. How the explanations of 

the co-chair and the Executive Director could be so different is still troubling to me.

THE FAILURE OF THE MODELS

GCMs are nothing more than hypotheses about the behavior of the atmosphere. 

The basic rule of science is that hypotheses do not graduate into facts unless they 

can be tested and validated against real data. As part of my review of the USNA in August 2000, I performed such a test. The 

results were very disappointing. Both CGCM1 and HadCM2 were incapable of simulating the evolution of ten-year averaged temperature changes (1991-2000, 1990- 

1999, 1989-1998, etc.... back to 1900-1909) over the United States better than a 

table of random numbers. In fact, the spurious 300 percent warming error in 

CGCM1 actually made it worse than random numbers, a dubious scientific achievement, to say the least. I wrote in my review: ‘‘The essential problem with the USNA is that it is based largely on two climate 

models, neither one of which, when compared to the 10-year smoothed behavior 

of the lower 48 states reduces the residual variance below the raw variance of 

the data [this means that they did not perform any better than a model that 

simply assumed a constant temperature]. The one that generates the most lurid 

warming scenarios—the . . . CGCM1 Model—also has a clear warm bias... All 

implied effects, including the large temperature rise, are therefore based upon 

a multiple scientific failure [of both models]. The USNA’s continued use of those 

models and that approach is a willful choice to disregard the most fundamental 

of scientific rules...For that reason alone, the USNA should be withdrawn from 

the public sphere until it becomes scientifically based.’’ The Synthesis Team was required to respond to such criticism. Publicly, they deflected this comment by stating that both U.S. temperatures and model temperatures rose in the 20th century, so use of the models was appropriate! This was a wildly unscientific response in the face of a clear, quantitative analysis. The real reason for the models’ failure can be found in the USNA itself (Figure 

11 in Chapter 1 of the USNA Foundation document). It is reproduced here as our 

Figure 2. The discrepancies occur because:

1. U.S. temperatures rose rapidly, approximately 1.2°F, from about 1910 to 1930. 

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bon dioxide, miss this warming, as by far the largest amounts of emissions were 

after 1930. 

2. U.S. temperatures fell, about 1.0°F, from 1930 to 1975. This is the period in 

which the GCMs begin to ramp up their U.S. warming, and 

3. U.S. temperatures rose again about 1.0°F from 1975 to 2000, recovering their decline between 1930 and 1975. 

It is eminently clear that much of the warming in the U.S. record took place before most of the greenhouse gas changes, and that nearly one-half of the ‘‘greenhouse era,’’ the 20th century, was accompanied by falling temperatures over the 

U.S. These models were simply too immature to reproduce this behavior because of 

their crude inputs. 

Despite their remarkably unprofessional public dismissal of a rigorous test of the 

USNA’s core models, the Synthesis Team indeed was gravely concerned about the 

criticism. So much so, in fact, that they replicated my test, not just at 10 year-intervals, but at scales ranging from 1 to 25 years. 

At the larger time scales, they found the models applicable to global temperatures. But over the U.S., not surprisingly, they found exactly what I had. The models were worse than random numbers. 

It is difficult for me to invoke any explanation other than political pressure that 

would be so compelling as to allow the USNA to continue largely unaltered in this 

environment. And so the USNA was rushed to publication, ten days before Election 

Day, 2000. 

Given the failure of the models when directly applied to U.S. temperatures, there 

were other methods available to the USNA team. One would involve scaling various 

global GCMs to observed temperature changes, and then scaling the prospective 

global warming to U.S. temperatures. The first part of this exercise has been performed independently by many scientists in recent years, and published in many 

books and scientific journals. It yields a global warming in the next 100 years of 

around 2.9 °F, which is at the lowest limit of the range projected by the IPCC in 

its Third Assessment Report. 

If applied to the United States this would similarly project a much more modest 

warming than appears in the USNA. Perhaps that is the reason such an obviously 

logical methodology was not employed after the failure of the models was discovered 

by a reviewer and then independently replicated by the USNA itself. 

EFFECT OF THE USNA

This discussion would be largely academic if the USNA were an inconsequential 

document. But, as noted above, it served largely as the basis for Chapter 6 of the 

U.S. Climate Action Report—2002. Further, it served as the basis for legislative 

findings for S. 556, a comprehensive proposal with extensive global warming related 

provisions, and it was clearly part of the findings for legislation restricting carbon 

dioxide emissions recently passed by the California Legislature. Hardly a week goes 

by without some press reference to regional alterations cited by the USNA. Would 

the USNA have such credibility if it were generally known that the driver models 

had failed? 

SOLVING THE STRUCTURAL PROBLEMS WITH THE USNA

The USNA synthesis team contains only two individuals who can logically claim, 

in my opinion, to be climatologists. Of the entire 14-member panel, there is not one 

person who has expressed considerable public skepticism about processes that were 

creating increasingly lurid scenarios for climate change with little basis in fact. As 

noted above, the administrative structure that selected the synthesis team was 

clearly directed by political appointees, which no doubt contributed to this imbalance. 

In my August 2000 review, I wrote: 

‘‘Finally, we come to the subject of bias in selection of USNA participants. There 

are plenty of knowledgeable climatologists, including or excluding this reviewer, 

who have scientific records that equal or exceed those of many of USNA’s participants and managers. They would have picked up the model problem [that 

extreme versions were selected, and that they could not simulate U.S. temperatures] at an early point and would not have tried to sweep it under the rug. 

Where is Bob Balling? Where is Dick Lindzen? Where are [Roger] Pielke Sr., 

[a participant in this hearing], [Gerd] Weber or [Roy] Spencer?’’

My review was tendered shortly after attending the annual meeting of the American Association of State Climatologists (AASC) in Logan, Utah, in August 2000. 

The AASC is the only professional organization in the U.S. devoted exclusively to 

climatology. Membership consists largely of senior scientists who are tasked by their 

56

states, usually through the state’s major universities, to bring climate information 

and services to the public. Until 1972, the State Climatologists were employees of 

the U.S. Department of Commerce. 

In my review of the USNA I further noted that: 

‘‘Yesterday . . . I returned from the annual meeting of the American Association 

of State Climatologists (I am a past president of AASC). There were roughly 100 

scientists present. I can honestly state that not one positive comment was tendered to me about the USNA, out of literally dozens made. If the report is published in anything like its current form, I predict it will provoke a public examination of how and why the federal science establishment [could have produced 

such a document].’’

That prediction has come true. It is why we are here today. 

Besides being research scientists, the State Climatologists are interpretive professionals who deal with the climate-related problems of their states on a day-to-day 

basis. It’s hard to imagine a better-suited team of professionals to provide a significant leadership role in any new Assessment. 

RECOMMENDATIONS

1. The current USNA should be redacted from the public record. 2. Another Assessment should be undertaken, this time with a much more diverse synthesis team 

selected by a more diverse political process. 3. Professional interpreters of climate 

information, who will be called upon to explain or defend any future Assessment, 

such as the State Climatologists, should provide strong input to any new report. 4. 

Any new Assessment must be based only upon hypotheses that can be verified by 

observed data. 

CONCLUSION

The 2000 document, Climate Change Impacts on the United States: The Potential 

Consequences of Climate Variability and Change, which served as the basis for an 

important chapter in the new Climate Action Report—2002, was based on two computer models which were extreme versions of the suite of available models. The two 

selected models themselves performed no better than a table of random numbers 

when applied to U.S. temperatures during the time when humans began to subtly 

change the composition of the earth’s atmosphere. As a result, both reports are 

grounded in extremism and scientific failure. They must be removed from the public 

record. 

This scientific debacle resulted largely from a blatant intrusion of a multifaceted 

political process into the selection process for those involved in producing the U.S. 

National Assessment. The clear lesson is that increased professional diversity, especially intermingling state-based scientists with the federal climatologists, would 

have likely prevented this tragedy from ever occurring. 

References 

IPCC (2001). Climate Change 2001: The Scientific Basis. Contribution of Working Group I to 

the Third Assessment Report of the Intergovernmental Panel on Climate Change. Houghton JT, 

Ding Y, Griggs DJ, Moguer M, van der Linden PJ, Dai X, Maskell K, Johnson CA, (eds). Cambridge University Press, Cambridge, UK, 881pp. 

National Assessment Synthesis Team (2001). Climate Change Impacts on the United States: 

The Potential Consequences of Climate Variability and Change. Report for the U.S. Global 

Change Research Program, Cambridge University Press, Cambridge, UK, 620pp. 

U.S. Department of State. U.S. Climate Action Report—2002. Washington, D.C., May 2002.

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Mr. GREENWOOD. Thank you. 

The Chair recognizes himself for 10 minutes for inquiry. 

Dr. Karl, I want to start with you. In your written testimony, you 

note several factors that cause climate change and variability that 

were not included in assessment models. This is on page 2 and 

more extensively on page 10. You also note that foreign models 

were problematic for use in the United States, and cite a National 

Research Council report which you chaired—this is from page 4 of 

your testimony—that underscored these important limitations. 

Can you explain why, given your own knowledge about the models’ limitations, you went ahead with these models? Weren’t they 

too limited for the public uses that would result from this report? 

Mr. KARL. Sure. I would be happy to, Mr. Chairman. 

The two models that were selected, by no means, were perfect 

models, and no model is perfect. I don’t think anyone would argue 

that. I think the question that we all asked ourselves is whether 

they would be useful tools. 

As I tried to indicate in my testimony, we believe they were quite 

effective as useful tools, along with the observational data and 

‘‘what if’’ scenarios. Maybe I can give you a little bit of an analogy. 

In daily weather forecasting today, operational weather models 

cannot predict tornados or hailstones, but yet our weather forecasts 

do give an idea of when we would expect tornados and hailstorms 

and are largely based on those operational weather models, despite 

the fact that the operational weather models do not have the high 

resolution details to be able to predict those phenomena. 

So in that sense, these models, we felt, were effective tools and, 

as I tried to indicate in my testimony, there was a number of 

issues that were neglected, those being changes in land use, as Dr. 

Pielke had described, changes in black soot and other aerosol, 

changes in stratospheric ozone depletion. 

Those simulations weren’t available at that time, but the intent 

of the assessment was to look into the 21st Century, and if you 

look at the IPCC results, those forcings, although are important 

and it is important to try and understand the regional details, the 

two most important factors, that being aerosols and increases in 

greenhouse gases, were included in the models. 

So for that reason, we thought that it was a valuable tool to go 

ahead and use and, in fact, if we had not used them, I think we 

would have been negligent. 

Mr. GREENWOOD. How do you respond to Dr. Michaels’ suggestion that these models haven’t produced more—anything different 

than a random set of numbers? 

Mr. KARL. Random numbers? Yes, and I am glad you asked that 

question, because we have conducted those tests on those models 

similar to what Dr. Michaels has suggested. First, let me qualify. 

There’s many tests you can do on models, and no one test should 

be used to say whether or not a model is effective. 

There’s been many types of tests applied to these models and 

other models, but I can say the same kind of tests that Dr. Michaels suggests was applied to precipitation data over the U.S., and 

the model showed significant skill. If you apply the same test to 

global temperatures, the models show significant skill. 

62

There is a number of reasons why we think it is inappropriate, 

actually, to apply that test on the national temperature or precipitation over the course of the 20th Century. That is, as I indicated, 

the models do not have all those forcings. They did not have volcanic eruptions. We know the U.S. climate record was affected by 

volcanic eruptions in the 20th Century. 

It did not have solar variability. Some of the changes were affected by solar variability. The timing of El Ninos and North Atlantic oscillations and other important oscillations are not in these 

models when they simulate climate. They are trying to produce the 

stoclastic behavior of climate, and they can’t predict the timing. 

So if you are looking at small regional scales where these effects 

are important in the historical record, it is going to be very difficult 

to evaluate a model. That is why most evaluations look at the global scale. They will aggregate regions, but they will aggregate it up 

globally to remove a lot of this noise and variability. When you do 

that, the models that we have used and many of the other models 

do show significant skill. 

In fact, a recent test by Lawrence Livermore National Laboratory 

looking at the annual cycle of precipitation and the total precipitation for the last 20 years showed that the Hadley Center model 2 

that was used in the assessment exceeds all other models, and they 

tested 24 models. This was part of a model inter-comparison project 

and has been going on for a number of years. 

The Canadian climate model did not do as well. It wasn’t an 

outlier. It was in, I would say, the lower third of the distribution 

of the models being used. So I think again it depends on what kind 

of tests you apply, and you have to look at the broad breadth of 

the scientific information that is out there, in my opinion. 

Mr. GREENWOOD. Dr. Michaels, you wanted to respond. Yes. 

Mr. MICHAELS. Yes. The standard test of whether—— Mr. GREENWOOD. What I need you to do is you see how this 

microphone points directly at my mouth. That’s what you need to 

do. If it is pointing over my head, you can’t hear. 

Mr. MICHAELS. The standard test of whether a model performs, 

a model being a hypothesis, is a statistical test against random 

numbers. Tom very adequately answered the question, and I would 

like to point out what is kind of missing from his response, which 

was in fact that he did replicate my experiment and found, as I 

found, on 10-year averages that it was worse than random numbers. 

He did it on 1 year averages, on 5 year averages, on 10 and on 

25 and found the same thing. Now we are talking about warming 

of the surface of the planet created by changes in greenhouse 

gases. After that surface and mid-atmosphere warm, that creates 

a change in the temperature distribution. That creates changes in 

precipitation. 

I think it is rather interesting to agree on this panel that we 

couldn’t simulate the temperature of the United States and somehow be happy about the fact that the precipitation was right, because it is the temperature change that drives the precipitation 

change. 

Here is the real problem, if you must know. We are going to have 

great difficulty simulating the temperature history of the United 

63

States with these models for one main reason. There was a large 

warm-up in the United States’ temperatures that occurred before 

the greenhouse effect changed very much, and then as the greenhouse gases began to ramp up into the atmosphere in the middle 

part of the century, the temperature dropped. In the latter part of 

the century, the temperature has returned to levels that are near 

the maxima that occurred after the large warm-up in the early 

20th Century. 

It is going to be very, very difficult to simulate that, because no 

one really understands why the first one occurred and why it was 

of such similar magnitude to the latter one, given the large 

changes in the atmospheric greenhouse effect. I am left to conclude 

that we could not use the models for even assessing the annual 

temperature of the United States, and the irony of this report is 

it then devolves into regional assessments after having admittedly 

failed now with United States temperature. 

I think we need to rethink the validity of this entire process. 

Mr. GREENWOOD. Let me ask a question that is a bit off the 

script here, but Dr. O’Brien talked about the need for a Manhattan 

project. I’d like the panelists, if you would, starting with Dr. 

Janetos and going right down the line, to offer up your sense as 

to whether there is a lack of resources here. Do we need to, in fact, 

apply governmental and/or private sector dollars in a very significant way to create resources, computer and intellectual, in order to 

get a better grip on this? 

Mr. JANETOS. Mr. Chairman, I would answer your question very 

briefly. Yes, we do. We have been very clear both in the National 

Assessment and in subsequent publications about the need for substantial additional research into the topics of vulnerabilities, and 

then to understand what changes, in fact, are the most plausible 

in the physical climate system itself. 

We have had a significant research program for sometime now, 

but this is one of the most challenging issues in both underlying 

biology, ecology, and the physics of the climate system that this 

country has had to address in environmental science, and I believe 

certainly deserves additional resources toward its investigation. 

Mr. GREENWOOD. Dr. Karl? 

Mr. KARL. Yes. I think one way to take a look at whether or not 

we need additional resources is to look back at some of the problems that we faced in the National Assessment, we attempted to 

do this. There were issues related to just understanding whether 

or not we had effective observations, not to simulate what the real 

climate is, but to look at the changes. 

You heard Dr. Pielke talk about changes in the mid-troposphere. 

There are some new results coming out that suggest, well, the increases of temperature were a little more than we perhaps thought. 

It just reflects this issue of trying to understand what is happening 

in the climate itself is complex, requiring significant investment in 

time and resources. 

Then the issue related to the models: We were severely constrained by the number of models that were able to simulate, for 

example, just a day/night temperature. Many of the ecosystem 

modelers said this was critical for them to be able to look at the 

impacts further down into the century. 

64

So it is very clear that we need the details of climate from the 

observations. We need many more improvements in the models. My 

sense is that there is plenty of work out there to be done and plenty that could be very effective in helping to do another national assessment, if we so attempt it. 

Mr. GREENWOOD. Dr. Lashof? 

Mr. LASHOF. Well, I certainly agree with that. We are investing 

quite a bit in the global change research program now. Additional 

resources certainly would be useful, and particularly the kind of detailed modeling center that Dr. O’Brien suggests, I think, would be 

very helpful in the United States. 

I would just add to that a caution, that the goal of furthering the 

research to get at many of the details that need to be addressed 

should not be posed as a substitute for the need to take action now 

to reduce emissions. 

I would just like to quote from the Intergovernmental Panel on 

Climate Change report, synthesis report from 2001, that says that, 

‘‘The pervasiveness of inertia and the possibility of irreversibilities 

in the interacting climate, ecological and socioeconomic systems are 

major reasons why anticipatory adaptation and mitigation actions 

are beneficial. A number of opportunities to exercise adaptation 

and mitigation options may be lost if action is delayed.’’ Mr. GREENWOOD. Dr. O’Brien, we know what your answer is, but 

perhaps you could elaborate on what you have in mind. 

Mr. O’BRIEN. Well, I am going to brag now. I have used more 

computer time than you probably imagine that a scientist and his 

students can use all my life. I can say for the absolute first time 

in my life I personally have adequate access to computer time. It 

is through two ways. 

One was when the Soviet Union surrendered, they finally 

changed procurement rules in the Department of Defense, and now 

in the Department of Defense they can buy computers. You know, 

in 1975 the poor guys inside Department of Defense had to guess 

what Kray and the other ones are going to have 8 years from now, 

because that is how long it took to buy a computer. 

We, fortunately, have ONR support, and I can get access to those 

for some of our ocean modeling. Florida State has invested in a 

large system which, as I’ll brag, has put us 3, 4 in the world, and 

the first in universities in the United States, and I am very happy. 

We know, for example, that why didn’t we have any U.S. models? 

Well, there are two institutions that historically we would look to. 

That is the Geophysical Dynamics Lab, NOAA’s lab in Princeton, 

and the National Center for Atmospheric Research, and neither one 

had adequate computer things to do these kind of models that our 

international partners are doing. 

You know, sir, in a word I want you to remember, computers are 

cheap. I find hundreds of young scientists, PhDs, working in these 

labs with absolutely inadequate computers, and you know, you figure out what the cost per manyear is for a PhD with all the support, and the computers these days with Moore’s law operating are 

really, really inexpensive. 

The other thing is that at NCAR I have been developing a new 

climate model, and I am putting their best scientists on it. But 

they want to go back to individual papers and things like that. I 

65

really believe, to advance this, this is a national emergency, the 

kind of cost that you mentioned yourself, that climate change is 

going to cost this country trillions of dollars and problems as we 

go down 10 to 20 years. We need to put it in a situation where it 

is outside the politics of whatever the history of that lab is, and 

something where, you know, young—bright, young scientists will 

take this as a challenge, that they can go there and work for a 

while. 

You know, there is an example in our government. You know, 

they are having their 30th anniversary. It is ICASE. Under NASA, 

you know, they have this little think tank for numerical modelers 

in other areas besides weather and climate, and it is at Langley, 

and it is the NASA Administrator’s budget, and it is an absolutely 

beautiful thing. 

They take the brightest young mathematicians that come out of 

our university systems, and put them in an environment in which 

they an really advance the understanding in areas like, you know, 

simulating, as someone said, aircraft and simulating other things. 

So I think it is really a priority, and I really think it is relatively 

cheap compared to the kind of money that we are spending on satellite systems, observing systems, that we really need to do this. 

I’m sorry to take so long. 

Mr. GREENWOOD. That’s quite all right. Dr. Pielke. 

Mr. PIELKE. Yes. I think there is a need to have a redirection of 

this effort, but I would like to focus more on the vulnerability perspective. That is, you start from that, and we have to assess 

vulnerabilities to environmental risks, societal risks, all kinds of 

risks that we can think of, and where does climate fit within that 

umbrella, and then develop plausible projections from both models, 

from historical record, artificial creation of data. 

This is, I think, a much more vibrant and inclusive approach 

than what the National Assessment did, because if we start from 

vulnerability and we find where our thresholds and our concerns 

are, that is where we can spend our resources. 

I think, in terms of developing better models, I would agree with 

Dr. O’Brien that we actually have a lot of computer tools available 

today, and we can do a lot more with these models. I think that 

needs to be integrated more into the process, some of the work with 

respect to land use change on the climate system, the multiple effect that aerosols have on cloud and precipitation. 

Climate is a very complicated problem. As I said in my testimony, I don’t think that predictability may be the ultimate goal to 

understanding of the climate process itself. That is why I fall back 

to the vulnerability paradigm, because that permits us to make decisions even if we don’t understand what exactly will happen in the 

future. 

Mr. GREENWOOD. Dr. Michaels? 

Mr. MICHAELS. Mr. Chairman, perhaps I spend too much time in 

Washington, but it would be hard for me to imagine a panel of scientists or agency heads saying that they didn’t need the money, 

and you always have to be very careful. 

Mr. GREENWOOD. We have a predictive model that predicted that 

you all would say this. 

66

Mr. MICHAELS. Yes. Now having said that, let me offer somewhat 

of an alternative point of view, first of all, on the assessment. I 

think that it probably would have been appropriate had there been 

more involvement from the State climatologist community, because 

we are the people who have to respond to the press more than anybody else, and the public, when these reports come out. If we had 

had more input, I think we would have been happier with the report. 

Having said that, I might be able to simplify the problem for you 

a little bit, and I am going to show you a picture. Mr. Chairman, 

in absence of a picture, I’ll paint you a picture. 

We have a number of computer models for the behavior of the 

atmosphere, and by and large, although there are a few outliers 

like the Canadian model, they predict straight line increases. They 

say once human warming starts from changes in the greenhouse effect, it takes place at a constant rate. I believe human warming has 

started from changes in the greenhouse effect, because I believe 

that human warming has started. 

Mr. GREENWOOD. So you are defining human warming as——

Mr. MICHAELS. Greenhouse warming has started as a result of 

this. 

Mr. GREENWOOD. All right. 

Mr. MICHAELS. So perhaps what we ought to do is to adjudicate 

all these straight lines. You see some of them are going up like 

this. Some of them are going up like this, and some of them are 

going up like this, and some of them are going up like that. Now 

all the models say that once the warming starts, it takes place at 

a constant rate. So why don’t we just plot the observed rate of 

human warming? 

You know what you get when you do that? You get something 

around 1.6 degrees Celsius over the next 100 years. I would think 

that our research effort should be attempting to answer the question why is the warming rate proceeding at the low end of the 

range of expectations, and why has it been so constant? 

I wish I could show you a chart right now to show you how constant it has been, and I think that that is the research question 

of the future. 

Again, my other answer is the next time around, let’s get more 

of the State people in these reports, because they are the ones who 

can take these reports to the public and explain them the best. 

Mr. GREENWOOD. Feel free to find your picture and show it to us 

when you find it. 

The Chair recognizes the gentleman from Florida, Mr. Deutsch, 

for 10 minutes. 

Mr. DEUTSCH. Thank you. How much confidence do we have in 

the climate projects at this point in time, and then specifically related to that, we have—You know, there’s different models and different scenarios. Can each of you comment on what is agreed to in 

these different models and scenarios? Maybe we could just go to 

Mr. Janetos. 

Mr. JANETOS. Yes, sir. In the models that we used in the assessment itself, there was a single underlying emission scenario. This 

is, in fact, a limitation of the assessment. The scenario—The emisVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00070 Fmt 6633 Sfmt 6602 W:\DISC\81495 81495
67

sions scenario that we chose was one that had been thoroughly examined internationally. 

So in one sense, one of the things that was agreed quite constant 

throughout the assessment was the underlying forcings of greenhouse gas accumulations and changes in sulfates and aerosols, for 

example. the models that were used—— Mr. GREENWOOD. Would you define forcings, because you have all 

been using that, and I am not sure that Mr. Deutsch and I understand. 

Mr. JANETOS. The changes in the impacts on the atmosphere 

that actually cause climate to change and to vary, in an abbreviated way. The models—All of the models that were used in the 

assessment shows some warming. There was obviously—over the 

U.S. There is obviously disagreement in the actual magnitude of 

that warming. 

They also show—They do show rather different changes in precipitation, which Dr. Karl has referred to in his testimony. In each 

case we actually—The analysis that we actually performed was to 

take the changes in the models and apply those to an interpolated 

dataset of the historical record of the United States. 

So the actual variability that was analyzed was drawn from the 

historical record itself. We did this in order to attempt to be conservative in our analyses, in particular with respect to changes on 

intra-annual and decadal time scales. Thank you. 

Mr. KARL. If I could address the question simply, there’s a number of items that I think everyone would agree on. One it is going 

to get warmer, and again, as Dr. Michaels has mentioned, the 

issues are how much warmer. That is why you will see in the IPCC 

reports this uncertainty range, and that is why I think it is important in these scenarios to look at that full range. 

So, clearly, being warmer is part of it, and then the implications 

of what happens when it is warmer, reduced snow pack, more rain 

versus snow, and you can imagine what some of those hydrological 

impacts might be. 

The other aspect that I think most of us would agree on is that 

we can only state in very general terms what we would expect to 

see with precipitation: Increase in mid and high latitude precipitation, generally globally more precipitation, subtropics perhaps less 

precipitation, and that dividing line between the subtropics and 

mid and high latitudes comes very close to the United States. That 

is why you see that we are very uncertain about just the exact sign 

of precipitation. 

One thing is also, I think, in general agreement. If it is not raining, with warmer temperatures, you generally have more evaporation, more evapotranspiration, depending—Here is where vegetation becomes important. So when you get down to local scales, if 

vegetation begins to change as temperatures increase, it could actually affect the amount of water that is being evaporated. 

So in the general sense, there is agreement when it’s not raining, 

more evaporation; but there is important regional and local scale 

differences that we probably would not all agree on. 

Last, one item, that again in general all the models that we have 

looked at, all the models that are available in the literature—you 

can argue from thermal dynamic considerations from some of the 

68

equations that we use in physics that, as the globe warms, precipitation tends to fall in heavier events. This is what all the models 

are projecting. 

We are beginning to see this in the observations. It doesn’t occur 

everywhere, but more areas we are seeing than areas we are not 

seeing it, and that is also reported in the IPCC report. 

So those are a number of the things, I think, that there’s some 

consistency that I think we might all be able to agree upon. 

Mr. DEUTSCH. Dr. Lashof. 

Mr. LASHOF. Thank you. Let me start by saying what we can’t 

do. Dr. Michaels has made this argument that the models are like 

a table of random numbers. But the test that he has applied is a 

very particular test, and it is a test that basically says can these 

models predict the weather in Philadelphia or Miami on July 25, 

2010 better than a table of random numbers. 

The answer to that is no. Why? Because 2010 is only 10 years 

from now, and over a 10-year period natural variability, El Ninos, 

volcanic eruptions that can’t be predicted, the general oscillations 

in heat between the atmosphere and the ocean system are of the 

same magnitude as the expected overall warming trend that’s a result of adding heat trapping gases to the atmosphere. 

So over a 10-year period you don’t expect to be able to do better 

than simply using roughly current conditions as your best predictor 

of the likely conditions then. Over a 30-year period or a 50-year period, then the effects of human alterations to the atmosphere dominate over these natural changes and, when you apply that test, the 

models do much better than a table of random numbers. 

So that’s the fundamental point. As a result of that kind of consideration, there is agreement, again accepted by this administration as well as the last administration, that warming during the 

21st Century will be larger than warming during the 20th Century. 

Again, Dr. Michaels said, well, why don’t we just take the observed data and draw a straight line through it. That’s okay. The 

problem is that, when you have data with some scatter and you 

take a relatively small period and you want to project out over a 

long, you can draw a lot of straight lines with different slopes, and 

it doesn’t help you answer the question how steep that slope is 

going to be. Again, that is why the models are useful. They give 

us more insight into that. 

Just a couple of other facts that are very robust to add to the 

ones Dr. Karl just mentioned. We expect sea level rise during the 

21st Century will be significantly more rapid than sea level rise 

during the 20th Century. That has obvious implications for your 

State, Mr. Deutsch. 

In addition, the effects on coral reefs are expected to be very severe. The reason for that is both the increase in temperature—

where coral reefs are already threatened by high sealable temperature events that cause coral bleaching, that becomes much more 

common—plus the direct effect of increased CO2 which, as the atmosphere accumulates more carbon dioxide, carbon dioxide increases the acidity of the ocean and literally erodes the corals. 

So if we continue to add carbon dioxide to the atmosphere, with 

high confidence we can say, and the National Academy says, that 

69

coral reefs are extremely vulnerable to being wiped out in many 

areas. Those are just a couple of examples. Thank you. 

Mr. O’BRIEN. One of the interesting things about the global models is that some of us near my age remember the first one by Jim 

Hanson from NASA GIS in which he told the Senate that we would 

increase 10 degrees Fahrenheit by 2020, but he had a very small 

computer. So he had no ocean in his model, and eventually the 

GCMs, which were putting oceans in—The trend that I mentioned 

in my report is that what I see in the models is that, as the models 

keep increasing, the magnitude of the impact out at 100 years is 

decreasing. 

I think that Dr. Michaels’ straight line—and I think there is 

probably only one—is a lower bound unless something else happens, because we might be going into an ice age, which has nothing 

to do with what man is doing to the planet. In fact, Mr. Deutsch, 

if you look in the back of my report, you will find out that where 

you live in south Florida is warming up, but most of Florida is actually cooling down. It is actually cooling down. 

I remind the panel that around 1880 in Savannah, Georgia, and 

Jacksonville, Florida, two wonderful places, they harvested tens of 

thousands of boxes of very good oranges which they shipped to Europe and to Washington and those areas, and now if you want to 

grow oranges, you have to be south of Orlando. 

So, clearly, part of the southeast has certainly not experienced 

this warming that some people are finding in the data. But I believe that the models will get better, and I believe that Dr. Pielke’s 

ideas about vulnerability and other effects are extremely important 

in order to direct the modelers that are not in an ivory tower just 

doing these physical models, and we are already working in those 

areas. 

You know, right now in the State of Florida, actually by using 

climate variability, we are actually now providing forest fire predictions, county by county, month by month. So there’s a lot to do 

in applied work, and I am very pleased that we have the support 

of that. 

So the models will get better as the resolution gets better. This 

is a known fact with weather prediction. You know, we went from, 

when I was in graduate school, about 250 kilometer on side grids 

until now, you know, the weather predictions are getting down to 

10 kilometers on a side, particularly at this European center that 

I mentioned earlier, and their forecasts for weather are getting 

very, very nice, much better than we have had in the past. 

So I really believe that we need these models. You know, also the 

Nation is investing a lot of new resources in the ocean. There is 

a large portion of the scientific community that believes that we 

also need to understand the ocean. The ocean is the flywheel in the 

climate system. It is the thing that will change, and I am sorry to 

tell you, Dr. Lashof, but the ocean’s pH cannot incorporate—The 

ocean is a very buffered system. 

Also the things about corals is somewhat a red herring. There’s 

later research. Remember, about 10 years ago the corals south of 

Florida were dying. They blamed it all on the El Nino. That was 

the era when everything was due to El Nino. In fact, actual experiments and in the literature, published not by me, of course, shows 

70

that, you know, a lot of this is natural, and sometimes the bleaching is actually beneficial for the coral for when they take their next 

bloom. 

It’s sort of like in northern Florida and Georgia, you know, if we 

don’t get any cooling in the winter, you don’t get any peaches. 

Thank you. 

Mr. PIELKE. Yes, sir. The fundamental hypothesis for these models is that we can predict the future change based on CO2 and 

other greenhouse gases and aerosols, and not just CO2 but the radiative effect of CO2, how it affects the greenhouse effect. But carbon 

dioxide has other effects such as biogeochemical effects, and there’s 

the land use change that we have already mentioned. 

These make it—These haven’t been included in the models. So 

we don’t know if they have predictive ability, but it is a necessary 

condition to test. As I showed in my testimony, the current suite 

of models that were used in the U.S. National Assessment have 

failed to replicate the atmospheric change over the last 20 years. 

The atmosphere has to warm in order to warm the surface, and 

as to why the surface has warmed and the atmosphere hasn’t, that 

is the subject of some controversy. But some of our initial work 

suggests maybe some of the surface data is not spatially representative. We can talk about that more, if you would like. 

For south Florida specifically, we have actually published papers 

on that subject, and we have shown, for example, the July, August 

warming that has occurred in south Florida over the past 80 years 

or so can be explained entirely by land use change, the fact of the 

draining of the marshes, the draining of the wetlands. Doesn’t 

mean that is the only reason that it has occurred, but we can explain it. That has not been included in the National Assessment. 

Finally, I would like to conclude this answer with just going back 

to the statement of my Society of the American Association of State 

Climatologists. We specifically concluded that climate projects have 

not demonstrated skill in projecting future variability in change in 

such important climate conditions as growing season drought, flood 

producing rainfall, heat waves, tropical cyclones, and winter 

storms, and these types of events have a much more significant effect on society than average annual global temperature trends, 

even if we could predict them correctly. 

Mr. MICHAELS. Thank you. I think, I’m sure inadvertently, Dan 

misrepresented my analysis. We weren’t just using 10-year decadal 

averages. We were looking at 10-year running means, 1991 to 

2000, 1990-1999, etcetera, on back through the historical record. 

He said that, if we had looked at 30-year averages, that would 

have been important. Well, I didn’t, but Tom Karl was so interested in our analysis that he did, and he found that the models 

over the U.S. for temperature, in fact, were no better than random 

numbers on 25-year averages. 

I would like to get back to this notion of what we know and what 

we don’t know. Both the House and Senate have considered— thrown considerable resources at us, probably about $10 billion 

over the years, to study this issue of climate change, and much of 

it has gone toward the modeling of climate change. 

Now I am going to believe that for that $10 billion we at least 

got the mathematical form of those models correct. This is the grab 

71

bag of models. I could get you a whole bunch of others. What you 

see is they are straight lines in general. The Canadian model is an 

outlier. 

Now the reason for this is simple. It is because we are adding 

carbon dioxide in the atmosphere at a slightly exponential rate, if 

I could draw your attention to my hand, slightly greater than a 

straight line, but the response of the atmospheric temperature to 

carbon dioxide is what we call a logarithm. It begins to damp off. 

If you add up an exponent and a logarithm, you get a straight line. 

That is what we have here. 

As the greenhouse era began, and we can, I think, see that when 

we see the cold air masses in Siberia start to warm up—that’s a 

real strong signal of a greenhouse. 

Mr. GREENWOOD. When was that? 

Mr. MICHAELS. That’s about around 1970 or so this begins to 

take place. We could plot the temperatures against this. I want to 

show you something. Now let me finish with an analogy. 

We have different weather forecasting models, and I teach 

weather forecasting at University of Virginia every once in a while, 

and some days the models will differ. We have the ADA model. We 

have the NGM model which stands for ‘‘no good model.’’ We have 

the ECMWF. We have all these models. What do you think we tell 

students, for all their tuition money, when we have all these different models forecasting slightly different weather for the next 3 

days? 

We tell them to look out the window. We tell them look at what 

is happening around the country, and see which model corresponds 

best to reality. That is what we do for the weather forecasting 

problem, and that is what this graph does for the climate forecasting problem. 

I draw your attention to the blue dots, once they start to go up, 

how remarkably little they depart from the straight lines. It’s just 

that the computers predict different straight lines. What has happened here—what explains this curve is not only the addition of 

the logarithmic and the exponential response, but a remarkable 

constant has emerged in our study of human influence on the atmosphere, which is the amount of carbon dioxide emitted per person is constant as population increases. 

Now we believe population is not going to increase as much as 

it was. This curve is a true indicator of what is happening, and I 

see absolutely no reason to believe that those constances are going 

to begin to suddenly depart from reality. 

Mr. GREENWOOD. I am going to recognize myself for an additional 10 minutes. 

Mr. DEUTSCH. Mr. Chairman, if I might, I have gotten a request, 

a unanimous consent request, that other members be allowed to 

submit statements and questions for the record. 

Mr. GREENWOOD. Without objection, they certainly will be. 

Dr. Pielke, in your testimony you described a policy statement of 

the American Association of State Climatologists which recommends that, ‘‘Policies related to long term climate not be based 

on particular predictions, but instead should focus on policy alternatives that make sense for a wide range of plausible scenarios.’’

72

Does this mean State climatologists, by and large, do not consider the National Assessment a useful tool for policymaking? 

Mr. PIELKE. Well, we didn’t specifically talk about the National 

Assessment. We talked about the climate change issue in general. 

I would think we would fall back on our comment No. 2 in our policy statement that recognizes that the models are—or that climate 

prediction itself was a very complicated problem, and that 

verification is also difficult, if not impossible, because you have to 

wait a long period of time in order to come up with the predictions. 

I think we also recognize as State climatologists that climate is 

much more complex than is implied by the U.S. National Assessment, since they didn’t, for example, include all the human 

forcings; and because of that, as I said a few minutes ago, we have 

concluded that there is no skill in any of these models, the IPCC 

or the U.S. National Assessment, for predicting these regional impacts of growing season, drought, flood producing rainfall and so 

forth. 

So even if the models did show global skill, which I don’t think 

they have, they certainly have not shown regional skill as voted on 

by nearly a unanimous vote of our Society. 

Mr. GREENWOOD. Thank you. Dr. Janetos, let me return to you. 

You note in your testimony that the report explicitly describes the 

synthesis team’s scientific judgment about the uncertainty inherent 

in each result. (a) Can you explain why this effect was sufficient, 

given the complexities of the undertaking, the public mindset, and 

the context in which the report would be taken? 

Mr. JANETOS. It was certainly our hope and our intent to signal 

to our readership, however wide or narrow it might have ended up 

being, our judgment about the robustness and confidence that we 

had in our major findings. To give you a particular example, results that were only found in one model run from one GCM and 

one ecological model, as extreme as they might have been, were 

judged to be of substantial—We had substantially less confidence 

in those results than findings that were consistent amongst either 

climate models or ecosystem models. 

It was certainly not our intent, nor the design of this report, to 

have it serve as the sole basis for national policymaking, and it obviously is not being used as such, as a sole basis for policymaking, 

which I think is wise. 

Many of us have subsequently collaborated on a publication in 

which we lay out our views of the scientific uncertainties and recommend programs for addressing those, which is currently in press 

in the peer reviewed literature. 

Mr. GREENWOOD. Thank you. Mr. Karl, do you believe the caveats about uncertainty were sufficient? 

Mr. KARL. Yes, I believe that we went to great pains to develop 

a lexicon, as Dr. Janetos had indicated, to try and convey where 

it was clear in our minds that there was considerably higher probability, given all the assumptions of the scenarios that were generated, of the outcomes. Then there were some where we tried to 

convey the information in the sense that we just didn’t know, and 

there was equal chances. 

So I thought that, in fact, the assessment followed a protocol that 

was begun in the first IPCC report in 1990 that tried to give asterVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00076 Fmt 6633 Sfmt 6602 W:\DISC\81495 81495
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isks, asterisks meaning one, two, three or four-star asterisks to try 

and convey some sense of confidence that the scientists had in the 

outcomes that they were expecting in the future. 

It was very clear when we were writing this report, words can 

be very deceiving. One individual may say likely, and it causes a 

whole different set of ideas to come to mind that, you know, maybe 

this is 95 percent certain. So we tried, and it is shown in the report—tried to use those words and link them with probabilities, not 

fixed probabilities but likely didn’t mean 95 percent. It was somewhere between 65 and 85, 90 percent. So we thought that this was 

a quite important thing to do. 

Mr. GREENWOOD. Any of the other panelists want to comment on 

the adequacy of the caveats? 

Mr. MICHAELS. Yes, I would, if you don’t mind. It has clearly 

been established here that both Tom and I agree that there was 

the problem of the two driver models doing no better than the table 

of random numbers, and on temperature, not on precipitation, temperature being a very important variable for agriculture and many 

of what we call the subsequent impact models. 

To use a colloquialism, that’s garbage, garbage in, and there is 

a transitive property of refuse when you apply it to subsequent 

computer models, and that’s what comes out. I have yet to understand, I have yet to hear a justification for proceeding along this 

road when the leadership knew that there was this problem with 

the models. 

I think they should have stopped and said, wait a minute, we 

need to report back to you that we really can’t go down this road, 

even though we were commanded to, because we don’t have the 

tools. They could have come to you and said, listen—I mean, they 

could have disagreed with me, that’s fine—we need a lot more 

money. We need a lot more support to study this problem and to 

give you what is an assessment that is based upon real numbers, 

not random numbers. That is my problem with the competence in 

this report. 

Mr. GREENWOOD. Thank you. Mr. Karl, can you elaborate on the 

timing of model improvements in your testimony? Can models ever 

provide a level of certainty needed to convince policymakers or 

even the State climatologists? 

Mr. KARL. First off, I would preface my comment that I think I 

will try and limit my comments to how the improvements in the 

models—how long it will take to narrow the uncertainties as opposed to when State climatologists or policymakers may choose to 

use them. 

I think that, if you take a look at history, you can get a good 

sense of how quickly we might be able to converge. If you look at 

this issue that really began to become a focus of the scientific community in the 1980’s, the first models that were generated—in fact, 

if you even look before that, the first National Research Council report talked about the sensitivity of models to doubling of carbon dioxide on the global average temperature, and they gave an uncertainty range that stands to this day today. 

That first report done by the NRC now is over 30 years old, and 

you will see that we still have the same range of uncertainty, you 

know, doubling of CO2, 1.5 to 4 degrees Celsius increase in temVerDate 0ct 09 2002 09:03 Oct 31, 2002 Jkt 082302 PO 00000 Frm 00077 Fmt 6633 Sfmt 6602 W:\DISC\81495 81495
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perature globally, and then the issues come down to, well, what is 

going to happen in the specific regions. 

I do see some significant improvements in the next number of 

years with the use of not only global models but coupling with regional climate models, putting in more of the regional details, as 

we have discussed. So there will be some improvements, but I 

would not expect that that range is going to change substantially 

in the next 5 or 10 years. 

If I may make one other comment with respect to some of Dr. 

Michaels’ statements regarding whether or not these models are 

better than a table of random numbers—and again, I don’t want 

to turn this into a scientific debate, but the way you apply tests 

to models is very important to know the framework. What’s the 

level playing ground? 

These models that were run had one simulation. We know that 

you need many simulations to adequately capture important climate fluctuations, and we don’t have that, and only if you have 

many, many different ensembles, orders of hundreds of climate 

model runs using the same forcings, can you hope to see what the 

scope of variability might be. 

These models did not include volcanic eruptions at the time they 

erupted, like Mount Pinatubo, El Chechon. So again there are—As 

I said in my testimony, my oral statement, there’s many different 

tests out there, and it’s very tenuous to put too much information 

on any single test. 

One other issue that’s come up related to the tropospheric temperatures, mid-troposphere, that Dr. Pielke has argued show less 

warming than models projected. I just wanted to point out, if you 

go back to the early Sixties, we have radiosonde data that go the 

early Sixties. The warming produced by the observations and the 

models on a global basis are quite consistent. 

Mr. GREENWOOD. Dr. Michaels, you wanted to respond? 

Mr. MICHAELS. That is true, Tom, except you know and I know 

that the warming that occurred in the radiosondes—these are the 

weather balloons—is a peculiar warming that shows a step function somewhere around 1975, 1976. 

In fact, if you take this weather balloon record and go from its 

beginning, which depending on the record you are using is 1956 

or—or 1957 or 1948—Take the 1956 to 1975, and it is constant—

or 1976. There is no warming. Then you take the 1977 to now or 

to the late 20th Century, and it is constant. 

There is this jump that occurred in the mid-1970’s. Some people 

call it the great climate shift. We have no idea what it was. We 

also have no computer model. O’Brien will explain it all. We have 

also no computer model that I know of for change in greenhouse 

gases that says all of a sudden the tropospheric temperature 

jumps. 

So it is a little misleading to say, yeah, those records match up, 

because the computer models are predicting a smooth change—you 

saw that—in the free troposphere, and the atmosphere isn’t obeying the law as specified by the computer. 

I think Tom and I are in agreement, by the way, largely. If I 

were to deconstruct, and as a college professor I am forced to do 

this—If I could deconstruct your answer about, well, Michaels’ test, 

75

you know, really was a little bit harsh, because he didn’t include 

volcanoes or something like that, isn’t Tom Saying that the models 

were inadequate for this report? 

Mr. GREENWOOD. I will let him answer that himself. Actually, we 

have a pending vote. So I am going to ask the last question of the 

hearing, and it is kind of a wide open question. 

That is this. The Congress and the Executive commanded that 

this study be done, but I want to ask each of you to respond to this 

question. If you had the power to command the Congress and the 

President with regard to the policies that we should enact and employ with regard to this entire range of global warming, everything 

from resources needed to study, the policy decisions with regard to 

emissions, how would you command us? Dr. Janetos? 

Mr. JANETOS. Mr. Chairman, a daunting question indeed. I think 

my command would be twofold. One would be to take those actions 

which make sense now, not to imagine that the uncertainty in the 

science acts as a break to inhibit mitigation activities that make 

sense—— Mr. GREENWOOD. Could you give us an example of those actions 

that you think we should take? 

Mr. JANETOS. I believe that some measure of mitigation for 

greenhouse gas emissions is in order, mitigation actions that are 

achievable with current technology and at reasonable cost. 

I also believe quite strongly that resources and a focused program on vulnerabilities and the sensitivities of natural resources to 

changes not only in climate but to other environmental stresses is 

in order. We face a changing planet. That is very clear. Ultimately, 

our well-being depends on our ability to manage those resources 

well. 

Mr. GREENWOOD. Dr. Karl. 

Mr. KARL. Well, one of the things that I think is most important 

to consider to try and move forward on this issue is the difficulty 

that we face when we try to go from discipline to discipline to understand the important impacts and the adaptations, the mitigation measures we might take. 

There is a tremendous amount of collegial interaction that must 

occur between physicists, climate scientists, ecologists, specialists 

in hydrology. One of the things we found in the National Assessment, I think, that was so valuable was, for the first time, these 

communities were actually talking together. Outputs from one 

model were looked to see how they might be able to run another 

model. Observations from one group were looked at how they might 

apply to another area. 

That activity is really critical, and it is dependent on individuals 

trying to forge these interactions, these discussions. So I think one 

of the important messages from the National Assessment, one area 

that really is important if we expect further progress in this area, 

is to continue and encourage anything we can do to encourage that 

dialog across disciplines. 

Most scientists get much more pats on the back by being specialists in their own field. So without a push in that direction, it is 

going to be very hard, I think, to expect individual scientists to—

although I’m not speaking for everybody, but I think letting the 

system go and expecting that to happen on its own will be difficult. 

76

Mr. GREENWOOD. Dr. Lashof. 

Mr. LASHOF. Mr. Chairman, we know that we are adding a thickening blanket of heat trapping pollution to the atmosphere in CO2

emissions from automobiles and power plants. We know that that 

is going to cause the climate to change, and indeed the climate has 

already begun the changes. I think everybody on this panel has 

recognized. 

The National Assessment shows that the United States is very 

vulnerable in many respects. We can’t predict what the weather 

will be on July 25, 2030, but we can say that there are very severe 

risks to the United States if we continue to add carbon dioxide to 

the atmosphere at the increasing rates that we have been. 

We also know that for the last 10 years we have had a voluntary 

approach to trying to limit the emissions of greenhouse gases, and 

it’s failed. Our emissions are going up. So I think that the basic 

conclusion is pretty straightforward. It’s time for mandatory limits 

on emissions of carbon dioxide and other heat trapping gases. 

The House has before it the Clean Smokestack Act sponsored by 

Congressmen Boehlert and Waxman that would take a big start on 

that, focusing on an integrated approach to cleaning up emissions 

from power plants. I think we need an energy policy that is designed to limit carbon dioxide emissions. Unfortunately, I believe 

that the policy that was passed by the House earlier in the year 

moves us in the wrong direction, and instead of, for example, 

strengthening efficiency standards for automobiles that would have 

the result of reducing emissions of CO2 and making us less vulnerable to dependence on foreign oil, it actually moves us in the wrong 

direction. It weakens currently law. 

So I think there are some very clear steps. You know, the good 

news is that this is a very daunting problem, but unlike some other 

problems like terrorism and poverty, I think we know how to solve 

this problem, and we just really need to get to work on it. So that 

would be my answer. Thank you. 

Mr. GREENWOOD. Dr. O’Brien. 

Mr. O’BRIEN. Mr. Chairman, I have two points here. One point 

is that, besides my colleague, Dr. Pielke’s, very good points about 

looking to see where the vulnerabilities are so you know where to 

put the emphasis on your studies, I believe that more—that Congress should direct the scientific community to start looking at understanding climate variability, and I mean how we vary on the 

scales of annual, multi-years and multi-decades, because these are 

the way that we finally get to this straight line. I think that just 

looking at what is going to happen 100 years from now is the 

wrong approach. 

I also believe—The second point is I believe that this changing 

climate variability and its understanding should be made a national security issue and not just a domestic issue. I feel sad to 

hear that we continue to focus today too much on just what is happening in the United States, but unfortunately with our standing 

in the world, you know, we are taking on responsibility for lots and 

lots of parts of the world, you know. 

You see lots of efforts both in the military and the civilian side, 

and I do believe that we need to think about other places in the 

world. You know, if climate variability destabilizes countries which 

77

are on the edge—and I’m not going to mention any now—you know, 

that is going to cause a great problem for our economy and our citizens. So I really believe that we should return to the idea that the 

changing climate in the future and its variability is really an important national security issue for the United States. 

Mr. GREENWOOD. Thank you, sir. Dr. Pielke. 

Mr. PIELKE. Well, first I would like to mention, I think we should 

move beyond the term global warming to the more inclusive term, 

which is human induced climate change; because I think it is 

multi-dimensional and multi-faceted, as our policy statement says. 

In the specific policy statement of my association, there are two 

bullets in there that I think address your question specifically. The 

first one is that policy responses to climate variability and change 

should be flexible and sensible. The difficulty of prediction and the 

impossibility of verification of predictions decades into the future 

are important factors that allow for competing views of a long term 

climate future. Therefore, the American Association of State Climatologists recommends that policies related to long term climate 

not be based on particular predictions but instead should focus on 

policy alternatives that make sense for a wide range of plausible 

climatic conditions, regardless of future climate. 

Climate is always changing on a variety of time scales, and being 

prepared for the consequences of this variability is a wise policy. 

Second, in our interactions with users of climate information 

AASC members recognize that the Nation’s climate policies must 

involve much more than the discussions of alternate energy policies. Climate has a profound effect on sectors such as energy supply and demand, agriculture, insurance, water supply and quality, 

ecosystem management, and the impacts of national disasters. 

Whatever policies are promulgated with respect to energy, it is 

imperative that policymakers recognize that climate variability and 

change has a broad impact on society. The policy responses should 

also be broad. Thank you. 

Mr. GREENWOOD. Dr. Michaels. 

Mr. MICHAELS. Mr. Chairman, as a CATO scholar, I guess I am 

going to have to be rational. The fact of the matter is that I believe 

what we should do now is not mandate technological programs and 

technologies that will not do very much about warming. 

When Mr. Gore came back from Kyoto in 1997, he asked the government scientists to project how much warming the Kyoto Protocol would save. The Protocol would require us to reduce our emissions 7 percent below 1990 levels, etcetera. Let me show you the 

calculation. 

The solid black line is the average temperature change from a 

suite of models if all the nations of the world did Kyoto. The 

dashed line underneath it—if we continued business as usual, I’m 

sorry. The dashed line underneath it is what happens if all the nations of the world did Kyoto. 

The change in global surface temperature exerted by Kyoto in 50 

years would be seven hundredths of a degree Celsius, fourteen hundredths of a degree Celsius in 100 years. 

If we really are concerned about this problem, I suggest rather 

than mandating technologies that we specifically allow people to retain their income to invest in the technologies of the future that 

78

this Congress and no one on this panel can define. One hundred 

years ago, the technology that ran our society was radically different than it is today. One hundred years from now, it will be 

radically different. It will be more efficient. It must be, because 

that is what a market determines. 

I think the best thing to do is to allow people to invest in those 

technologies, their own choice, rather than having governments, 

perhaps mistakenly, invest other people’s monies in technologies 

that simply will not accomplish what many people on this panel 

think needs to be accomplished. 

I believe our change to a less carbon based economy is an historical inevitability. All we have to do is get out of the way. 

Mr. GREENWOOD. You would command us to command less. 

We thank all of our witnesses for your presence and your testimony, and excuse you now. This hearing is adjourned. 

[Whereupon, at 11:45 a.m., the subcommittee was adjourned.]

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