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Charney Report

A report of the Ad Hoc Study Group on carbon dioxide and climate for the National Research Council chaired by Massachusetts Institute of Technology meteorologist Jule Charney estimates “the most probable global warming for a doubling of CO2 to be near 3°C with a probable error of ± 1.5°C.”

The forward to the 22-page “Charney Report” by Verner Suomi, Chairman of the Climate Research Board of the National Research Council, notes that “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.”  Suomi directs a cautionary warning to policymakers:  “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 addition to characterizing the impact of the oceans in delaying observable atmospheric warming, the study explores the impact of both positive and negative feedback mechanisms:  “A strong positive feedback mechanism is the accompanying increase of moisture, which is an even more powerful absorber of terrestrial radiation.  We have examined with care all known negative feedback mechanisms, such as increase in low or middle cloud amount, and have concluded that the oversimplifications and inaccuracies in the models are not likely to have vitiated the principal conclusion that there will be appreciable warming.  The known negative feedback mechanisms can reduce the warming, but they do not appear to be so strong as the positive moisture feedback.”*


*Jule G. Charney and others, Carbon Dioxide and Climate: A Scientific Assessment (National Academy of Sciences 1979),