Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page R1
Carbon Dioxide and Climate: A Scientific Assessment Carbon Dioxide and Climate: A Scientific Assessment Report of an Ad Hoc Study Group on Carbon Dioxide and Climate Woods Hole, Massachusetts July 23–27, 1979 to the Climate Research Board Assembly of Mathematical and Physical Sciences National Research Council NATIONAL ACADEMY OF SCIENCES Washington, D.C. 1979
OCR for page R2
Carbon Dioxide and Climate: A Scientific Assessment NOTICE The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the Councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the Committee responsible for the report were chosen for their special competencies and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. Available from Climate Research Board 2101 Constitution Avenue Washington, D.C. 20418
OCR for page R3
Carbon Dioxide and Climate: A Scientific Assessment Climate Research Board Verner E.Suomi, University of Wisconsin-Madison, Chairman Francis P.Bretherton, National Center for Atmospheric Research Dayton H.Clewell, Mobil Oil Corporation (retired) Thomas Donahue, University of Michigan Herbert Friedman, Naval Research Laboratory J.Herbert Hollomon, Massachusetts Institute of Technology Charles W.Howe, University of Colorado John Imbrie, Brown University Robert W.Kates, Clark University John E.Kutzbach, University of Wisconsin-Madison Cecil E.Leith, National Center for Atmospheric Research William A.Nierenberg, Scripps Institution of Oceanography Roger R.Revelle, University of California, San Diego Joseph Smagorinsky, National Oceanic and Atmospheric Administration Frederick E.Smith, Harvard University Karl K.Turekian, Yale University John Waelti, University of Minnesota Sylvan H.Wittwer, Michigan State University Warren Wooster, University of Washington LIAISON WITH FEDERAL AGENCIES Eugene W.Bierly, National Science Foundation John G.Dardis, Department of State Edward Epstein, National Climate Program Office, National Oceanic and Atmospheric Administration
OCR for page R4
Carbon Dioxide and Climate: A Scientific Assessment Steven Flajser, Committee on Commerce, Science and Transportation, U.S. Senate Elbert W.Friday, Department of Defense Lawrence R.Greenwood, National Aeronautics and Space Administration Galen Hart, Department of Agriculture Keith Howard, Department of the Interior Gerald J.Kovach, Committee on Commerce, Science and Transportation, U.S. Senate Ian Marceau, Subcommittee on Natural Resources and Environment, U.S. House of Representatives Lloyd J.Money, Department of Transportation Douglas H.Sargeant, National Oceanic and Atmospheric Administration David Slade, Department of Energy Herbert L.Wiser, Environmental Protection Agency STAFF John S.Perry, National Research Council, Executive Secretary Robert S.Chen, National Academy of Sciences, Resident Fellow
OCR for page R5
Carbon Dioxide and Climate: A Scientific Assessment Ad Hoc Study Group on Carbon Dioxide and Climate Jule G.Charney, Massachusetts Institute of Technology, Chairman Akio Arakawa, University of California, Los Angeles D.James Baker, University of Washington Bert Bolin, University of Stockholm Robert E.Dickinson, National Center for Atmospheric Research Richard M.Goody, Harvard University Cecil E.Leith, National Center for Atmospheric Research Henry M.Stommel, Woods Hole Oceanographic Institution Carl I.Wunsch, Massachusetts Institute of Technology STAFF John S.Perry Robert S.Chen Doris Bouadjemi Theresa Fisher
OCR for page R6
Carbon Dioxide and Climate: A Scientific Assessment ERRATUM p. 9, Section 3.2, 3d paragraph, line 6 should read as follows: “atmosphere-earth system would absorb about 0.9 W m−2 less solar radiation”
OCR for page R7
Carbon Dioxide and Climate: A Scientific Assessment Foreword Each of our sun’s planets has its own climate, determined in large measure by the planet’s separation from its mother star and the nature of its atmospheric blanket. Life on our own earth is possible only because of its equable climate, and the distribution of climatic regimes over the globe has profoundly shaped the evolution of man and his society. For more than a century, we have been aware that changes in the composition of the atmosphere could affect its ability to trap the sun’s energy for our benefit. We now have incontrovertible evidence that the atmosphere is indeed changing and that we ourselves contribute to that change. Atmospheric concentrations of carbon dioxide are steadily increasing, and these changes are linked with man’s use of fossil fuels and exploitation of the land. Since carbon dioxide plays a significant role in the heat budget of the atmosphere, it is reasonable to suppose that continued increases would affect climate. These concerns have prompted a number of investigations of the implications of increasing carbon dioxide. Their consensus has been that increasing carbon dioxide will lead to a warmer earth with a different distribution of climatic regimes. In view of the implications of this issue for national and international policy planning, the Office of Science and Technology Policy requested the National Academy of Sciences to undertake an independent critical assessment of the scientific basis of these studies and the degree of certainty that could be attached to their results. In order to address this question in its entirety, one would have to peer into the world of our grandchildren, the world of the twenty-first century. Between now and then, how much fuel will we burn, how many trees will we
OCR for page R8
Carbon Dioxide and Climate: A Scientific Assessment cut? How will the carbon thus released be distributed between the earth, ocean, and atmosphere? How would a changed climate affect the world society of a generation yet unborn? A complete assessment of all the issues will be a long and difficult task. It seemed feasible, however, to start with a single basic question: If we were indeed certain that atmospheric carbon dioxide would increase on a known schedule, how well could we project the climatic consequences? We were fortunate in securing the cooperation of an outstanding group of distinguished scientists to study this question. By reaching outside the membership of the Climate Research Board, we hoped to find unbiased viewpoints on this important and much studied issue. The conclusions of this brief but intense investigation may be comforting to scientists but disturbing to policymakers. If carbon dioxide continues to increase, the study group finds no reason to doubt that climate changes will result and no reason to believe that these changes will be negligible. The conclusions of prior studies have been generally reaffirmed. However, the study group points out that the ocean, the great and ponderous flywheel of the global climate system, may be expected to slow the course of observable climatic change. A wait-and-see policy may mean waiting until it is too late. In cooperation with other units of the National Research Council, the Climate Research Board expects to continue review and assessment of this important issue in order to clarify further the scientific questions involved and the range of uncertainty in the principal conclusions. We hope that this preliminary report covering but one aspect of this many-faceted issue will prove to be a constructive contribution to the formulation of national and international policies. We are grateful to Jule Charney and to the members of the study group for agreeing to undertake this task. Their diligence, expertise, and critical judgment has yielded a report that has significantly sharpened our perception of the implications of the carbon dioxide issue and of the use of climate models in their consideration. Verner E.Suomi, Chairman Climate Research Board
OCR for page R9
Carbon Dioxide and Climate: A Scientific Assessment Preface In response to a request from the Director of the Office of Science and Technology Policy, the President of the National Academy of Sciences convened a study group under the auspices of the Climate Research Board of the National Research Council to assess the scientific basis for projection of possible future climatic changes resulting from man-made releases of carbon dioxide into the atmosphere. Specifically, our charge was To identify the principal premises on which our current understanding of the question is based, To assess quantitatively the adequacy and uncertainty of our knowledge of these factors and processes, and To summarize in concise and objective terms our best present understanding of the carbon dioxide/climate issue for the benefit of policy-makers. The Study Group met at the NAS Summer Studies Center at Woods Hole, Massachusetts, on July 23–27, 1979, and additional consultations between various members of the group took place in subsequent weeks. We recognized from the outset that estimates of future concentrations of atmospheric carbon dioxide are necessarily uncertain because of our imperfect ability to project the future workings of both human society and the biosphere. We did not consider ourselves competent to address the former and recognized that the latter group of problems had recently been reviewed in considerable detail by the Scientific Committee on Problems of the Environment (SCOPE) of the
OCR for page R10
Carbon Dioxide and Climate: A Scientific Assessment International Council of Scientific Unions. We therefore focused our attention on the climate system itself and our ability to foretell its response to changing levels of carbon dioxide. We hope that the results of our study will contribute to a better understanding of the implications of this issue for future climate and human welfare. In our review, we had access not only to the principal published studies relating to carbon dioxide and climate but also to additional unpublished results. For these contributions, we gratefully acknowledge the assistance of the following scientists: A.Gilchrist, British Meteorological Office J.Hansen, Goddard Institute for Space Studies, NASA S.Manabe, R.T.Wetherald, and K.Bryan, Geophysical Fluid Dynamics Laboratory, NOAA We also had the benefit of discussions with a number of other scientists in the course of the review. We wish to thank the following individuals for their helpful comments: R.S.Lindzen, Harvard University C.G.Rooth, University of Miami R.J.Reed, University of Washington G.W.Paltridge, Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia W.L.Gates, Oregon State University Finally, I wish to express my appreciation to the members of the Study Group for their contributions. In particular, the report benefited greatly from Akio Arakawa’s careful examination of the results of general circulation model studies. Our group is also grateful to the staff of the Climate Research Board for their support. Jule G.Charney, Chairman Ad Hoc Study Group on Carbon Dioxide and Climate
OCR for page R11
Carbon Dioxide and Climate: A Scientific Assessment Contents 1 SUMMARY AND CONCLUSIONS 1 2 CARBON IN THE ATMOSPHERE 4 3 PHYSICAL PROCESSES IMPORTANT FOR CLIMATE AND CLIMATE MODELING 7 3.1 Radiative Heating 7 3.2 Cloud Effects 9 3.3 Oceans 10 4 MODELS AND THEIR VALIDITY 12 4.1 Three-Dimensional General Circulation Models 13 REFERENCES 18 BIBLIOGRAPHY 20 APPENDIX: Comparison of Snow-Ice Effects in the Models Examined 21
OCR for page R12
Carbon Dioxide and Climate: A Scientific Assessment This page intentionally left blank.