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Ms. RIVERS. So there was a very direct and very severe response? Mr. ROHRABACHER. That is correct.

Ms. RIVERS. Which is what we would look for whenever anyone steps over their bounds.

Mr. ROHRABACHER. That is correct. That is correct.

Mr. BAKER. Mr. Chairman?

Mr. ROHRABACHER. That is correct. Thank you very much.

Mr. BAKER. Mr. Chairman?

Ms. RIVERS. I have another inquiry.

Mr. ROHRABACHER. First of all, the Chairman will rule that that was not a parliamentary inquiry.

Ms. RIVERS. Okay. This one will be.

Mr. ROHRABACHER. Well, I am sorry, you are not recognized. We have another member asking for recognition.

Mr. Baker?

Mr. BAKER. Some of us came here to hear today's witnesses, not to replow the old ground.

Mr. ROHRABACHER. If the lady does have a parliamentary inquiry, she has a right to express her parliamentary inquiry.

Mr. ROEMER. Mr. Chairman, I would just ask unanimous consent. I think the gentlelady is trying to state a parliamentary inquiry, and I would say this

Mr. ROHRABACHER. The Chairman agreed with that, and let's hear what it is.

Ms. RIVERS. Given that this Committee has already made decisions, many of them hostile, in this area about funding

Mr. ROHRABACHER. Would the lady express her parliamentary inquiry?

Ms. RIVERS. Yes. I will right now.

Mr. ROHRABACHER. Instead of insulting the Chair.

Ms. RIVERS. I did not know the facts would insult the Chair, but that

Mr. ROHRABACHER. If you will not desist-if you will express your parliamentary inquiry and quit insulting this Committee by claiming a parliamentary inquiry in order to prevent us from hearing the first panel.

What is your parliamentary inquiry?

Ms. RIVERS. My parliamentary inquiry is, if we receive information today that leads us in another direction than where the Committee has already gone, how will the Committee reconsider its decision?

Mr. ROHRABACHER. Excuse me? Excuse me. What is your parliamentary inquiry? Are you meaning to try to have a speech here, a political speech to try to prevent us from hearing the panel? Or do you have a parliamentary inquiry?

Ms. RIVERS. No. You are talking much more than I am.

Mr. ROHRABACHER. That is enough. We will call the first panel, and I would request that members, if they use the method of parliamentary inquiry, if they expect to have a way of handling one another with civility, which is the purpose of our parliamentary system, that they not make a mockery of the parliamentary system by claiming time and using our time in a way that takes away from the central effort of the day.

Would the first panel please be seated.

Our first panel today will address the issue of climate modeling. Peter Guerrero is Director of the Environmental Protection Issues for the General Accounting Office.

In July of this year, the General Accounting Office published a study on the limitation of generally used climate models.

Dr. Jerry Mahlman directs the Geophysical Fluid Dynamics Laboratory at NOAA at Princeton's Laboratory.

And Dr. Patrick Michaels is Assistant Professor of Environmental Science at the University of Virginia, and has been a leading spokesman on the issue of global warming.

And with that gentlemen, would you like to proceed?

Dr. Guerrero?

STATEMENT OF PETER F. GUERRERO, DIRECTOR, ENVIRONMENTAL PROTECTION ISSUES, RESOURCES, COMMUNITY, AND ECONOMIC DEVELOPMENT DIVISION, UNITED STATES GENERAL ACCOUNTING OFFICE

Mr. GUERRERO. Thank you, Mr. Chairman.

I will summarize my remarks, and our full statement has been submitted for the record.

Thank you for this opportunity to testify before the Subcommittee as it focuses on the issues concerning the use of models to predict future climate change.

My testimony is based on GAO's report on the limitations of these models that we issued this past July.

The report looked at two issues. First, factors limiting the ability of the model to accurately predict climate change, and second, the amount of federal expenditures for the modeling efforts.

In general, we found that the models were better today than they were a decade ago at predicting climate change. Despite these improvements, however, their accuracy was still limited.

One limiting factor stems from the fact that scientists do not fully understand how certain climate processes, such as cloud formation, will interact with greenhouse gases. As a result, the models currently provide only incomplete or inaccurate representations of these processes, and this introduces uncertainty into the predictions made by the models.

A second limiting factor is insufficient computing power to process the vast quantities of data required to more accurately simulate the changes in climate. Modelers try to overcome this limitation by introducing assumptions that deliberately simplify some operations in order to free computer time for other, more critical operations. These simplifications can affect the accuracy of the models' predictions.

To help the GAO assess the state of progress modelers have made in dealing with these kinds of issues, the Interagency Subcommittee on Global Change Research arranged, in the fall of 1994, for a special forum on global change modeling.

The forum brought together a representative set of scientists, both converts and skeptics, to develop a consensus statement on the issues related to the use of global climate models and their estimates of future climate change.

The assembled scientists developed a ranking system from "virtually certain" to "uncertain" that characterizes the major findings

and implications stemming from the models and issues currently being debated in the scientific literature.

At one end of the spectrum are those statements of high certainty that do not stem directly from climate models but are largely based on measurements, observations, and well-established scientific principles.

For example, scientists agree that greenhouse gases, such as CO2, absorb and readmit infrared radiation; that atmospheric concentrations of CO2 and other greenhouse gases are significantly above preindustrial levels; and that increased concentrations of greenhouse gases exert a global warming influence.

The global climate models in turn incorporate both existing knowledge, as well as assumptions about inadequately understood matters, such as the role of clouds in global warming, to predict future climate.

The forum participants felt certain some of these predictions were more probable than others. For example, an increase in the global surface temperature from one to 3.5 degrees Fahrenheit by the year 2050, a reduction in northern hemispheric sea ice and a rise in global sea level were all considered to be very probable results of increased concentrations of greenhouse gases.

Scientists, on the other hand, have less confidence in the probability of other outcomes such as increased mid-latitude drought and changes in tropical storm intensity.

In short, Mr. Chairman, the models are considerably better now than they were a decade ago at predicting future climate change, and the scientists involved have varying degrees of confidence in the models' capability to predict certain outcomes.

The accuracy of their estimates, however, is limited by a number of factors, including inadequate understanding of climate processes and feedback mechanisms, limited computing power, and the necessity of using simplifying assumptions and structures to deal with these limitations.

These limitations do not change the likelihood that climate will respond to increased greenhouse gas emissions. They do however limit scientists' ability to predict with certainty how the climate will respond, how much warming will occur, how soon it will occur, and what the impacts will be on regional climates.

Several on-going efforts are underway to address the current limitations of these models. Scientists are working to develop models that better reflect interactions among various climate components, and that provide a more complete understanding of key processes, such as cloud feedback.

Approximately a third of the U.S. Global Change Research program's 1995 budget was devoted to conducting research aimed at improving scientific understanding and ability to model such proc

esses.

Steps have also been taken to provide increased computer capacity needed to improve the scientists' ability to run these complex models without having to make the simplifying assumptions that reduce their accuracy.

Given the complexity of these challenges, scientists believe that significant reductions in the current uncertainties of predicting cli

mate change will require sustained efforts over the next decade or longer.

Mr. Chairman, this concludes my remarks. I would be pleased to answer any questions.

[The prepared statement of Mr. Guerrero follows:]

PREPARED STATEMENT OF PETER F. GUERRERO, DIRECTOR, ENVIRONMENTAL PROTECTION ISSUES, RESOURCES, COMMUNITY, AND ECONOMIC DEVELOPMENT DIVISION, UNITED STATES GENERAL ACCOUNTING OFFICE

Mr. Chairman and Members of the Subcommittee:

We appreciate the opportunity to appear before the Subcommittee as you focus on issues concerning the use of climate change models. Over the past century, human activity has increasingly emitted heat-trapping greenhouse gases, such as carbon dioxide, into our earth's atmosphere. As these emissions have grown, so too has concern over how they will affect our climate in years to come. Temperature increases could begin to melt the polar ice caps, raise the sea level, and alter patterns of precipitation. These effects could lead to serious consequences such as severe flooding. On the other hand, actions to reduce greenhouse gas emissions in order to avoid potential catastrophic effects of global warming could have significant economic consequences, and must be based on a sound understanding of the issues. One such major issue that should be considered when discussing the implications of global warming and the appropriate actions to control greenhouse gas emissions, is the range of projected temperature increases and the degree of uncertainty in these estimates. In July of this year, we reported on the limitations of general circulation computer models used to make such predictions.1 These sophisticated computer models consist of complex mathematical equations that represent various climatic processes and interrelationships among variables, such as seasonal changes in sunsight and global air currents. Our testimony today is based on our July 1995 report.

In general, we found that general circulation models are better now than they were a decade ago at predicting future climate changes. Nevertheless, the accuracy of the models' estimates is still limited. Specifically, we reported that:

-For general circulation models, as for other computer models, the quality of the output depends upon the quality of the input-the models are only as good as the data and scientists' understanding of how the climate system works. One limiting factor is that the models currently provide only incomplete or inaccurate representation of some of the processes, such as cloud formation, affecting climate because scientists do not fully understand how the climate system responds to these processes. As a result, models can produce different projections of future climatic conditions, such as global temperature.

-A second major limiting factor is insufficient computing power to process the vast quantities of data required to more accurately simulate changes in the global climate. Modelers try to overcome this limitation by introducing assumptions that deliberately simplify some operations in order to free computer time for other, more critical operations. These simplifications can affect the accuracy of the models' esti

mates.

-To improve the accuracy of general circulation models' estimates, scientists are developing models that better incorporate the processes affecting the climate system and that better reflect the interactions between or among the ocean and the atmosphere. They are also developing larger and faster computers that could process data for smaller areas. Given the complexity of the climate processes that need to be incorporated in the models, scientists believe that significant reductions of the uncertainties in projecting changes and trends in the climate will require sustained efforts that are very likely to require a decade or more.

BACKGROUND

General circulation models are the most highly developed tools available to help understand the global climate system's response to greenhouse gas emissions. Scientists use three types of general circulation models to predict climatic change: atmospheric, oceanic, and coupled. In general, atmospheric models predict the physical behavior of the atmosphere. Oceanic models represent the physics of the ocean. Coupled models, which scientists regard as the most advanced type of model, physically join the atmospheric and oceanic models. In the United States, the development of

1 Global Warming: Limitations of General Circulation Models and Costs of Modeling Efforts (GAO/RCED-95-164, Jul. 13, 1995).

general circulation models is supported through the coordinated efforts of the U.S. Global Change Research Program and five federal agencies.2

During the Forum on Global Climate Change Modeling, held in October 1994, scientists agreed that the buildup of greenhouse gases is creating an enhanced greenhouse effect that will lead to global warming.3 They estimated that the surface temperature of the earth will rise by 1 to 3.5 degrees Fahrenheit from 1990 to 2050 if emissions continue to grow without restriction. More recently, the International Panel on Climate Change reported that human activities are increasing the atmospheric concentration of greenhouse gases and that this increase will raise the global mean temperature between 1.8 and 6.3 degrees Fahrenheit by 2100.4 FACTORS LIMITING THE ACCURACY OF MODELS' ESTIMATES

General circulation models' estimates of future climatic changes are considerably better than they were a decade ago. The models have demonstrated skill in simulating many aspects of the observed climate, providing useful indications of future climatic conditions. For example, atmospheric models have demonstrated some skill in portraying aspects of atmospheric variability, such as the surface temperature of the sea. Oceanic models have simulated the general circulation of the ocean, including the patterns of principal currents. Coupled models, though still prone to small scale errors, have simulated the current climate on a large scale as well as portrayed atmospheric and oceanic behavior over large regions.

Though much progress has been made, the models remain limited in their ability to estimate, with desired accuracy, the magnitude, timing, and regional distribution of future climatic changes. These limitations stem from scientists' imperfect understanding of the climate system and computers' insufficient capacity to perform the detailed calculations needed to make more precise estimates.

Incomplete or Inadequate Representation of Processes Affecting Climate

According to the U.S. Global Change Research Program, general circulation models include the most important processes-such as radiation, convection, and water vapor-that affect the climate. However, the extent to which they incorporate and accurately represent these processes and their interactions varies and can affect the accuracy of the models' estimates. For example, some climate processes are not included or fully incorporated, even in the more advanced coupled models. And for some of the more important climate processes and interactions that are included in models, their representation is less than adequate primarily because scientists do not fully understand the climate system.

Atmospheric and oceanic models include fewer processes than coupled models where the oceans and the atmosphere meet, such as oceanic pressures, climatic fluctuations, and the effects of winds at the surface of the oceans. Consequently, these models' simulations are more limited and, in some cases, less accurate. For example, a 1991 test of atmospheric models produced systematic errors in the projections of sea level pressure, temperature, wind, and precipitation.

Coupled models more accurately simulate current climatic conditions than either atmospheric or oceanic models, but their estimates of temperatures and precipitation still deviate from actual conditions. For example, in an experiment conducted by the National Center for Atmospheric Research, the models estimated wintertime ocean temperatures were 7 degrees warmer than observed temperatures for the icebound region of Antarctica and 9 degrees colder than observed temperatures for the tropics. Scientists believe that the deviations stem from gaps in their understanding of the interactions between atmospheric and oceanic variables.

Although today's general circulation models include many of the most important feedback mechanisms (e.g., water vapor and clouds) they do not yet adequately represent the interactions of these mechanisms with greenhouse gases. Such interactions can amplify, dampen, or stabilize the warming produced by increased concentrations of greenhouse gases. Modelers do not fully understand the effects of feedback mechanisms and have not learned how to represent them with sufficient accuracy. Modelers have clarified the role of water vapor and improved their ability to model its effects. However, they are still seeking to understand and accurately

2 These five agencies are the Department of Energy, the National Aeronautics and Space Administration, the National Science Foundation, the National Oceanic and Atmospheric Administration, and the Environmental Protection Agency.

3 The purpose of the Forum, convened to respond to GAO and White House Office of Science and Technology Policy questions, was to produce a consensus document on issues concerning the use of climate models and to provide policymakers with information on future climatic changes. The International Panel on Climate Change was established in 1988 by the United Nations Environment Programme and the World Meteorological Organization to assess scientific and technical information about climatic change.

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