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persons from a wide spectrum of political viewpoints, all of whom wish to preserve the environment.

RESPONSES TO WRITTEN QUESTIONS SUBMITTED BY HON. JOHN MCCAIN

TO DR. RICHARD S. LINDZEN

Question 1. Your written statement refers to the limitations of computer models. In two recently released studies, computer models showed that the ocean warming that has been measured over the last half-century is exactly what would he expected from the amount greenhouse gases that have been emitted into the atmosphere. Tim Barnett of Scripps Institution of Oceanography is quoted as saying "This will make it much harder for naysayers to dismiss predictions from climate models." Would you comment on these recent reports?

Answer. The arguments in both papers are fundamentally circular as have been all attribution claims so far. What both papers show is that in response to rising surface temperatures of the past 50 years or so, there has been an increase in ocean heat content. Nothing controversial here. The emphasis of Levitus et al on the quantity of heat in the ocean is simply a statement that the heat capacity of the ocean is high; this is the reason for the ocean delay. Again no surprise. The claim that the observation confirms an anthropogenic cause is arrived at by looking at climate models which stimulate the observed surface temperature history by considering the joint effects of increasing C02 and aerosols. The argument goes that if models can stimulate the surface temperature, and if observations show then deep ocean heat content responds to surface temperature, then deep ocean heat content is responding to anthropogenic forcing. However, the aerosol forcing (which is crucial to stimulations) is so uncertain that it constitutes in essence an adjustable parameter (or parameters) which can be adjusted to produce a fit. The arguments of Levitus et al and Barnett et al then boil down to a peculiar assertion that if one can adust models to fit observations, the models must be right. Not exactly normative science.

That said, Barnett et al do mention some important things in passing. One was the role of the 'regime change' in the 1970's. This may be the real origin of temperature increase over the past 30+ years. The radiosonde data shows a very sharp increase in tropospheric temperature around 1976, with the surface temperature catching up over the following ten years (ocean delay again). This may be the reason for discrepancy between the satellite MSU data and surface data: the satellite data begins in 1979, after the atmospheric temperature rise occurred. As Barnett et al mention, the models don't show the regime change, and, therefore, the temperature rise they produce by adjusting aerosol forcing is likely due to the wrong reason. A second, was the comment that the coupled model they used was rather insensitive to anthropogenic forcing. This is important for the following reason: for sensitive models, the ratio of surface temperature to radiative forcing at the surface is high (this is the meaning of sensitivity), and low radiative forcing will cause the ocean to take longer to accumulate a given amount of heat. Relatively rapid heating of the deep ocean generally implies low climate sensitivity. In a paper by myself and Giannitsis in the Journal of Geophysical Research about 3 years ago, we looked at the observed response to volcanic sequences in order to estimate climate sensitivity: the range 0.3-1.2C for a doubling of CO2 appeared most likely (We are following the conventional practice of expressing sensitivity in terms of the response to doubling CO2). More recently, at the meeting of European Geophysical Society a couple of weeks ago, we did the same for the surface response to regime change and with the same result. Barnett et al really can't do the same since they don't know the actual forcing.

Which brings me to the final point: although both papers claim to have made an attribution (spuriously as far as I can tell), neither claims to have established any sensitivity, and it is the question of climate sensitivity that is crucial. Attribution without determining sensitivity is a fairly abstract exercise with no practical implication per se.

Finally, it should be pointed out that when these two papers compared observations with model outputs, the agreement was not particularly good.

Question 2. On the IPCC process, you have stated the vast majority of the participants played no role in preparing the summary, were not asked for agreement. Can you elaborate on this statement?

Answer. The IPCC directorate chooses the coordinating lead authors for each chapter. There were 13 chapters in the Working Group I report. Then a team about 15-30 lead authors are assembled for each chapter, and finally another 40-50 contributing authors are chosen for each chapter. (The numbers are approximate) Each 2-5 pages has about 2–3 lead authors responsible for their preparation with assist

ance from contributing authors. Only the lead authors, however, attend the meetings where their pages are prepared and reviewed. The meetings are held around the world. For Working Group 1, the meetings were in Paris, Arusha in Tanzania, Auckland in New Zealand, and Victoria in British Columbia. Although each lead author may comment on the whole chapter, in practice, the lead authors generally concern themselves with the pages they are expert in. After the chapters are completed (in the case of Working Group I, this happened in August 2000), the coordinating lead authors prepare a draft of the Summary, which is then studied by the directorate as well as representatives from government, industry and NGOs who proceed to rewrite the summary. This was done in Shanghai in January 2001 for the Working Group I report. The resulting Summary for Policymakers is not subject to approval by any of the authors. Moreover, the directorate reserves the right to modify the chapters in order to make them consistent with the summary. This is done with the assistance of the coordinating lead authors. The text is not issued until months after the Policymakers Summary.

Question 3. You have mentioned that the preparation of the report was subject to pressure. You said that you personally witness co-authors being forced to use their green" credentials in defense of their statements. Can you explain these "green" credentials?

In the sections on water vapor of Chapter 7 (Physics of Climate), there were three lead authors (myself, Herve Letreut of France, and Ray Pierrehumbert from the University of Chicago). Although Letreut is a modeler and Pierrehumbert is a Sierra Club activist, and both wanted to stress that the models might be right with respect to the crucial water vapor feedback, we all agreed that the relevant physics should be briefly reviewed with errors from previous IPCC reports corrected, and that the potential problems be explained. When, the writeup failed to include the traditional bromides of the first and second assessments, the coordinating lead author, Thomas Stocker of Switzerland, who knew nothing about the water vapor feedback, insisted that the pages be rewritten to produce what was expected, and accused the three of us of being unduly influenced by my allegedly contrarian and suspect views. However, I had intentionally stayed out of the writing, and Herve and Ray were forced to explain that they were actively pro-environmental and supportive of global warming: they were only trying to tell the truth. The scene was truly pathetic, and was witnessed by others.

Question 4. Background: Last year I introduced a bill, titled "International Climate Change Science Commission Act", to established an International scientific commission to assess changes in global climate patterns and to conduct scientific studies and analysis for other nations. Given your experience with the IPCC, are you recommending that the US and other countries rely upon another scientific body such as the International commission that I proposed last year?

Answer. I am not familiar with your bill. However, I am not sure how the US would go about creating an international commission. Certainly, it might be possible to create such a commission without a tie to any negotiations, and a permanence that would be independent of 'crisis' and a charge that included understanding, monitoring, and eventual forecasting of climate change regardless of its cause.

Question 5. You have stated that if we view Kyoto as an insurance policy, it is a policy where the premium appears to exceed the potential damages, and where the coverage extends to only a small fraction of the potential damages. In your opinion, what type of damages would not be covered?

Answer. If one considers most warming scenarios, and carefully estimates the costs (viz Questions 2 from Sen. Kerry), they are at worst comparable to the estimated costs of Kyoto, while Kyoto will, at best, help us to avoid only a small fraction of the projected warming.

RESPONSE TO WRITTEN QUESTIONS SUBMITTED BY HON. JOHN KERRY
TO DR. RICHARD S. LINDZEN

Question 1. You have stated repeatedly and with some certainty that a doubling of carbon dioxide in the atmosphere will produce a warming of 1 degree Celsius at most. The IPCC has expressed far greater uncertainty in its estimate of the warming impact of a doubling of atmospheric carbon dioxide, offering a range of 1.5 to 5.8 degrees Celsius. On what do you base your conclusion and why do you make that conclusion with such confidence that you don't suggest a range of warming? Answer. In my written testimony, I mentioned that the response to double CO2 alone, without feedbacks from clouds and water vapor, would produce about 1C warming. This is what virtually everyone involved gets. I also mentioned that higher values resulted from positive water vapor and cloud feedbacks in the models

which have never been confirmed in the observations. Indeed the wide range of model results (which for a doubling of CO2 remain in the range 1.5-4C which is what was given in the 1979 Charney Report of the NRC) results largely from the erratic behavior of clouds in the models. The IPCC range is based on the range of results produced by current models plus uncertainties in emissions scenarios with the highest value based on a scenario which more than doubles CO2. In recent papers (including one in preparation), we have sought observational estimates of sensitivity and feedbacks, and have pretty much narrowed things to a range of 0.3 to 1.2C which represents (in percentage terms) as great an uncertainty as the IPCC model range of results. In a paper by myself and Constantine Giannitsis, we looked at the temporal response to volcanic eruptions which provides a direct measurement of sensitivity. In another paper by myself, Ming-Dah Chou, and Arthur Hou, we used data to estimate a negative cloud feedback completely absent from models which essentially cancels model positive feedback—even if the latter were correct, which seems unlikely.

Question 2. You argue that warming observed in recent decades "represents what is on the whole a beneficial pattern." You have also suggested that future warming may have beneficial impacts on the whole. What specific imnpacts do you view as beneficial and what impacts do you view as harmful in drawing that conclusion? What nations will benefit the most from warming? What nations will benefit the least or be harmed by warming?

Answer. With respect to my remark in the testimony, "that warming is likely to be concentrated in winters and at night. This is an empirical result based on data from the past century. It represents what is on the whole a beneficial pattern," the answer is fairly obvious: longer growing seasons, less frost, fewer cold related deaths, lower heating bills, less likelihood of older citizens moving to the moving to the sun-belt. In addition, there are the benefits from CO2 fertilization: greater agricultural productivity with less need for water. The dangers are more speculative. Some endangered species may be stressed further, and some changes in preferred agricultural crops may be disadvantageous. Most scenarios of a catastrophic nature, refer to storminess, sea level rise, droughts, floods, etc., but these are even considered by the IPCC to be speculative since observational evidence is very weak, and in the case of extra tropical storminess, and variability, theory suggests the opposite (as noted in my written testimony). Finally, although I believe current models exaggerate the magnitude of warming. the coupling of these models to economic models with due concern for the detailed impact of climate change on specific sectors leads to a positive impact of GDP in most of the world. The figure is taken from a report by Prof. Robert Mendelsohri of Yale using Jim Hansen's model at the Goddard Institute for Space Studies. It shows most of the Northern Hemisphere benefitting, while parts of equatorial Africa and South Asia suffering reduced GDP.

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