APPENDIXES

APPENDIX I

Responses to Additional Questions

QUESTIONS FROM SENATOR MALCOLM WALLOP, FOR WEDNESDAY, MAY 6, 1992,

WITNESSES

1. Today's hearing is on the science of Global Climate Change. In the mid-1970's this committee heard testimony about the impending ice age, today's testimony addresses the science of temperature increases brought on by the same greenhouse gases (See attached quotes.) Why should we believe that today's witnesses are any better informed than our 1970 witnesses?

2. Testimony before the Committee suggests that, based on modeling, there is a consensus that the earth should be warming at a rate of 0.3 degrees C per decade at the surface (IPCC 1990, 1992) and even more in the layer measured by satellites. However, actual surface data show almost no trend at all in the past 50 years which also encompasses the period of greatest carbon dioxide increase. What does this suggest about the accuracy of the models to forecast surface temperatures?

3. Recent work by Danish scientists indicate that solar activity and northern hemisphere-temperature data had a correlation coefficient of 0.95, probably the highest ever found in this type of effort.

a. What do you make of this finding? If there is a real cause and effect relationship here, what would that mean with regard to the hypothesis concerning manmade enhancement of the greenhouse effect?

b. How does this correlation compare with the correlation between observed temperature and those calculated using global climate change models?

c. Do you think we need to do more science in this area? When will the science be available to determine whether there is a cause and effect relationship?

4. Recent surveys suggest substantial disagreement among scientists over the rate and magnitude of future climate change. For example, the State University of New York survey of 118 scientists indicated that 52 percent of them estimated that the rate of warming during the next century would be less than the IPCC prediction of 0.3 degrees C per decade.

a. Why is there such disagreement among the scientists? What are the major areas of disagreement?

b. When will the science be available to enable a true "scientific consensus" on the issues?

5. How would you characterize the accuracy and limitations of state-of-the-art of the models used to forecast potential climate changes?

When will scientists be able to understand and incorporate into the models a better understanding of physical processes, a coupling of the ocean-atmosphere, the radiative effects of clouds, the role of water vapor, biological feedbacks, etc?

If these processes were understood today, do we have the computers that would be capable of incorporating the new science and providing output on a timely basis? When will such computers be available?

6. The statement is often made that because of the long lifetime of carbon dioxide, we can't afford to wait to get the evidence before we act.

a. How is the lifetime of carbon dioxide in the atmosphere calculated? How well does it track with what we assume are the natural and man-made sink and source strengths of CO2, and the historical rate of CO2 accumulation in the atmosphere? How robust are these calculations?

b. Please comment on the calculations done by Heimann referred to in Dr. Bindzen's paper? Why is this any more or less believable than other calculations?

(265)

c. If Heimann is correct, then what objection is there to waiting for a decade or two (per Schlesinger and Jiang's paper) while we reduce the scientific, technical and economic uncertainties even as we allow technological improvements to proceed to help us mitigate and adapt to potential climate change more economically?

7. Whether warming will be in the 1.0 degree C range or in the 5 degree C range by 2100 seems to depend very heavily upon what assumptions GCM's employ to model the rate of formation, and the vertical and horizontal distribution, of water vapor.

a. It is true that GCM's predict negative water vapor in some regions? Is it also true that adjustments are made in the GCMs to deal with this?

b. What is the physical basis for these adjustments? Is this true of all GCM's? c. Is it true that even though the density of water vapor varies by 1000-fold between the surface and 10km, the models have about 10 to 20 vertical layers?

d. What kind of errors may be introduced because of such a simplification?

8. Dr. Lindzen stated that there are errors of the order of 50 percent in the calculations of atmospheric motion in GCM's. (Atmospheric motion redistributes much of the heat received by the tropics to the other "less-sunny" zones, and from the surface to higher altitudes.)

a. What "adjustments" are made in GCM's to make sure that the current climate comes out right?

b. Do these have a basis in physics or are they "fudging" (or "tuning") the model to get the right result?

c. What kind of results do you get for the current climate and for doubled-CO2 if there is no tuning?

9. A recent issue of "Science" indicates that the global ocean may actually take up 2.1 billion tons of carbon per year. Previous estimates have been lower, implying a huge unidentified terrestrial sink.

a. How much carbon do the oceans take up?

b. If the recent Science article is correct, what would be the policy implications, especially with regard to the need to stabilize or reduce carbon dioxide emissions by a certain date?

QUESTIONS BASED ON MARSHALL INSTITUTE REPORT

10. Massive amounts of data are becoming available through recent and more sophisticated measuring techniques, such as the use of satellites and related instrumentation. Has this data been analyzed? Is it reflected in the 1992 IPCC update? 11. The recent Marshall Institute update observes that highly accurate satellite measurements of the earth's temperature show that global temperatures have hardly changed in the last 12 years.

a. If your models are correct, and considering the large amounts of carbon dioxide and other greenhouse gases that have been discharged into the atmosphere, shouldn't temperatures have changed during this period?

12. Precise satellite measurements show only a 0.06 degree Centigrade increase in the 1980's, compared to the IPCC report that forecasts 0.3 degree Centigrade. a. What does this say about the models, or the consensus among scientists? b. How well do surface-based globally average temperatures compare to satellite data?

c. How good is the correlation for the Northern Hemisphere, the United States, the Southern Hemisphere? What are the reasons for the differences?

13. The recent Marshall Institute report concludes that if global warming were occurring, a greenhouse signal would be greater warming in the Northern Hemisphere by about 0.5 degree Centigrade; however, observed temperatures show no significant difference in temperature trends in the Northern and Southern temperature.

a. Would you agree with this observation? If so, on what basis can it be concluded that global warming is in occurring?

b. On what basis can it be concluded that the observed warming corresponds at best to anything but a low sensitivity to greenhouse gases?

14. The recent Marshall Institute report concludes that if global warming were occurring higher latitudes should already have warmed by 1.0 degree Centigrade more than lower latitudes; however, temperature records show no significant difference. Would you agree with this observation? If so, how can you conclude that global warming is in occurring?

QUESTION BASED ON THE 1992 UPDATE BY THE INTERNATIONAL PANEL ON CLIMATE

CHANGE (IPCC)

15a. In the 1990 IPCC Assessment, the best estimate of globally averaged temperature change was calculated to be 3.0 degrees C by the year 2100. The recent update reduces this somewhat (to about 2.8 degrees C). However, even this estimate does not account for any cooling due to sulfates or due to ozone depletion caused by CFC's. Nor does it account for the observed decreases in the build-up of methane or for volcanic activity.

If these factors are included in the models, what would be the new "best estimate" of globally averaged temperature rise by the year 2100?

b. Neither the original nor the updated IPCC estimates of temperature change included any cooling that could result from the cumulative impacts of volcanic activity between 1990 and 2100. Jim Hansen in his written testimony to this Committee on November 9, 1987 indicated that volcanic activity could reduce globally averaged temperatures by 0.5 degrees C to 1.0 degrees C by 2019.

Suppose we were to assume that future volcanic activity between 1990 and 2100 were similar to that which occurred over the previous 110 years, how much would that drop the "best estimate" and the range of temperature change by 2100?

16. The recent update by the International Panel on Climate Change seems to focus on temperature changes. However, water availability and soil moisture would seem to be much more critical for the well-being of human beings and other species. a. What can you tell me about what will happen to these two climatic variables? b. I would like to know what changes will happen on a regional or local levelwhat would this do to crops, natural resources and for society and the economy? c. How much confidence do you have in your ability to forecast regional climate change? How long will it take to improve our ability to predict regional changes with some degree of confidence?

17. The "February 1992 IPCC Supplement" details new findings related to the cooling effect of aerosols, and the slowed rate of increase of methane and halogen compounds.

a. Are these findings not also significant? Do these findings not buy us more time to improve the science?

b. What will be their impact on previous forecasts related to the potential timing and magnitude of climate change?

18. The "February 1992 IPCČ Supplement" states that: "Findings of scientific research since 1990 do not affect our fundamental understanding of the science of the greenhouse effect and . . . or do not justify alteration of the major conclusions of the first IPCC Scientific Assessment."

a. Do you agree with this statement? Please explain the basis for your position. b. If this is the case, does the recent IPCC report then go on to state that "most recent scientific information indicates that CFC's are global warming neutral, or might even cause some cooling. This statement seems to be in sharp contrast to the First IPCC Assessment Report which indicated CFC's contribute about 24 percent to the change in radiative forcing. Isn't this a "very" significant change in the IPCC's position?

c. What will be the impact of this apparently new scientific information on the modeling forecasts related to temperature increases, sea level rise, etc.? Does this mean we have more time to improve the science, and that warming, if it materializes, will be less than presently forecasted and will take longer to materialize?

19. The February 1992 IPCC Supplemental Report mentions that warming over considerable areas of the Northern Hemisphere continental land masses is primarily due to an increase of nighttime rather than daytime temperatures.

a. What does this imply with respect to the type of mitigation actions being considered by policy-makers?

b. Does this mean, assuming it is happening globally, that the consequences of potential climate change would not be as severe?

c. Could such temperature increases be beneficial? How long will it take before this matter could be more fully investigated?

20. The "1992 IPCC Supplement" states (page 30): "Since the 1990 report there has been a greater appreciation of many of the uncertainties which affect our predictions of the timing, magnitude and regional patterns of climate change. These continue to be rooted in our inadequate understanding of..."

a. Does this clearly imply that more science is needed before taking mitigation measures that could have serious social and economic implications on society?

b. How much more time is necessary before the science is available to remove the major uncertainties?

ADDITIONAL QUESTIONS FOR Dr. Watson

21. Dr. Watson, I am concerned about what is meant by the term "consensus" when it is used to described the science of global warming. For example, the IPCC report states on page 7, "The size of this warming is broadly consistent with climate models". Senator Gore, who repeatedly cites the IPCC consensus, recently stated that "only two scientists" disagreed with him on the subject of global warming.

However, I also have read the Science and Environmental Policy Project letter that is signed by over fifty atmospheric scientists-specialists in the field, and not alien to the discipline. Their letter states that

they are concerned about the agenda for UNCED which used the IPCC as its scientific basis,

• there is no consensus about the cause of the slight warming of the last 100 years, and

⚫ theoretical climate models used to predict future warming cannot be relied upon and are not validated by the existing climate record.

These two statements by Science and Environmental Policy Project letter and the IPCC are simply not consistent, yet each statement is endorsed by many eminent scientists.

a. Faced with this apparent disagreement within the scientific community, how can you and the IPCC claim that their statement represents any meaningful consensus?

b. How is the policy maker to respond to the over fifty of your colleagues—who are just as esteemed as you are? Your statements suggest that we are supposed to ignore them?

22. Dr. Watson, a March 24, 1992 article in the Los Angeles Times, March 24, 1992 quotes you saying:

We may be overstating the problem [global warming]. We may be understating the problem. That's what makes it a very difficult situation for government and industry.

23. The recent IPCC Update reports that lower stratospheric ozone depletion have offset the radiative forcing of increases of CFC's over the last decade. Is this conclusion supported by published peer-reviewed results? If not, why was there a rush to report this conclusion?

24. In view of possible delays in the launch of the Earth Observing System (EOS), how is NASA planning to collect the space based data that are important to understanding global climate change?

25. How are NASA and other CEES agencies planning to implement the CLIMSAT program?

ADDITIONAL QUESTIONS FOR DR. MACCRACKEN

21. A 1991 paper published by your colleague at Lawrence Livermore Laboratory, Dr. Stanley Crotch, "A Statistical Intercomparison of Temperature and Precipitation Predicted by Four General Circulation Models with Historical Data" seems to show that our climate models begin with significant errors in estimating the temperature of polar regions even before the greenhouse effect has changed. The errors are, in general, as large as the warmings that are forecast over those regions for a doubling of carbon dioxide.

Interestingly, these are the same areas in which the a greatest changes are forecast. Therefore, massive errors as large as the predicted changes in climate-are being made in the regions that are forecast to contribute most to global warming. Given this behavior, how can you, or anyone, defend the IPCC statement that "The size of this warming is broadly consistent with climate models"?

22. A study of the 1991 IPCC document suggests that global temperatures for the last 70 years have averaged below those projected by the IPCC's lowest warming scenario.

Doesn't this strengthen the position of those who have stated that this the global warming issue is being exaggerated?

23. Dr. McCracken, you stated that the Dutch had done a study which indicated that the cost of protecting the Dutch coast against sea level rise of 100 cm. to be 1 percent of GNP.

a. Could you please check this number and provide the Committee with any correction.

b. In fact, didn't the Dutch do a study (reported in the IPCC First Assessment) that indicated the total cumulative global cost of protection at $500 billion over the

100(+) years it might take the sea to rise 100 cm., which is at the upper end of the IPCC's 1990 (non-updated) best estimate?

c. How large is this estimate if this were discounted to present value (as is appropriate) and compared to the current global GNP?

ADDITIONAL QUESTION FOR DR. STEPHEN H. SCHNEIDER

21. Dr. Schneider in 1990 you stated in the Scientific American that:

the atmosphere's heat-trapping ability has been well established. There is virtually no doubt among atmospheric scientists that increasing the concentration of carbon dioxide and other gases will increase the heat trapping [ability of the earth's atmosphere] and warm the climate.

However in 1976 in the professional journal Science you stated:

An increase by a factor of 4 in the equilibrium dust concentration in the global atmosphere, which cannot be ruled out as a possibility within the next century, could decrease the mean surface temperature by as much as 3.5 degrees K (on the Kelvin scale, which equals 6.3 degrees on the Fahrenheit scale). If sustained over a period of several years, such a temperature decrease could be sufficient to trigger an ice age!

I recognize that both of these statements may be supported by scientific evidence. One of them deals with concentrations of carbon dioxide and the other deals with dust. I also recognize that the scientific data available in 1976 was not sufficient enough to predict global climate changes with any accuracy.

As a policy maker trying to understand the science of climate change, what is the basis for me assuming that the scientific data is any more reliable today?

RESPONSES TO WRITTEN QUESTIONS FROM DR. WATSON

INTRODUCTION

I would like to note for the record that I believe that the 1990 and 1992 Intergovernmental Panel on Climate Change (IPCC) scientific assessments represent a balanced view of the state of scientific understanding. They accurately reflect what is known and what key uncertainties remain. The documents were each prepared and peer-reviewed by several hundred of the worlds best scientists, and then reviewed and adopted by scientific experts within governments. The reports clearly represent the views of the large majority of the worlds "climate" scientists.

Question 1. Today's hearing is on the science of Global Climate Change. In the mid-1970's this committee heard testimony about the impending ice age, today's testimony addresses the science of temperature increase brought on by the same greenhouse gases (See attached quotes.) Why should we believe that today's witnesses are any better informed than our 1970 witnesses?

Answer. The issues are de-coupled and the two views are not inconsistent. On the long time scales of geologic change, i.e., tens of thousands of years, the Earth's climate should be moving towards an ice age. However, it is now recognized that over the next few decades or centuries the Earth may experience a significant_global warming due to anthropogenic emissions of greenhouse gases (including carbon dioxide, methane, nitrous oxide, and tropospheric ozone) possibly offset to some degree by the increase in the atmospheric loading of sulfate aerosols and particles from biomass burning.

Question 2. Testimony before the Committee suggests that, based on modeling, there is a consensus that the earth should be warming at a rate of 0.3 degrees C per decade at the surface (IPCC 1990, 1992) and even more in the layer measured by satellites.

However, actual surface data show almost no trend at all in the past 50 years which also encompasses the period of greatest carbon dioxide increase. What does this suggest about accuracy of the models to forecast surface temperature?

Answer. The models do not predict that the Earth should have warmed by 0.3 degrees centigrade per decade over the last 50 years. The models predict that the Earth should have warmed by about: (i) 1 degree C since the pre-industrial era, compared with an observed increase of 0.3-0.6 degrees C; and (ii) 0.5 degrees C over the last 50 years, compared with an increase of one or two tenths of a degree C. The predicted changes in temperature, due to the observed increases in the atmospheric abundances of greenhouse gases over the last 50 years, may have been either masked by natural variability or overpredicted because of other human activities, i.e., ozone depletion caused by anthropogenic emissions of chlorine and bromine con