Policy Analysis No. 329

Long Hot Year: Latest Science Debunks Global Warming Hysteria

Executive Summary

The national media have given tremendous play to the claims of Vice President Al Gore, some federal scientists, and environmental activists that the unseasonably warm temperatures of this past summer were proof positive of the arrival of dramatic and devastating global warming. In fact, the record temperatures were largely the result of a strong El Niño superimposed on a decade in which temperatures continue to reflect a warming that largely took place in the first half of this century.

Observed global warming remains far below the amount predicted by computer models that served as the basis for the United Nations Framework Convention on Climate Change. Whatever record is used, the largest portion of the warming of the second half of this century has mainly been confined to winter in the very coldest continental air masses of Siberia and northwestern North America, as predicted by basic greenhouse effect physics. The unpredictability of seasonal and annual temperatures has declined significantly. There has been no change in precipitation variability. In the United States, drought has decreased while flooding has not increased.

Moreover, carbon dioxide is increasing in the atmosphere at a rate below that of most climate-change scenarios because it is being increasingly captured by growing vegetation. The second most important human greenhouse enhancer — methane — is not likely to increase appreciably in the next 100 years. And perhaps most important, the direct warming effect of carbon dioxide was overestimated. Even global warming alarmists in the scientific establishment now say that the Kyoto Protocol will have no discernible impact on global climate.

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Patrick J. Michaels, a professor of environmental science at the University of Virginia, is a senior fellow in environmental studies at the Cato Institute.