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FROM VOLUME 5, NUMBER 3, MARCH 1992

NEWS...
IPCC ASSESSMENT UPDATE

Item #d92mar96

The scientific assessment working group of the Intergovernmental Panel on Climate Change (IPCC) agreed on a supplement to its 1990 assessment at a January meeting in China. While it does not advocate any major changes in the original assessment, the group concluded that sulfate aerosol haze in the lower atmosphere generated by industrial activities has probably offset a large fraction of the global warming influence of greenhouse gases to date, particularly in the Northern Hemisphere. The conclusion, based largely on research published by Charlson et al. in the January 24, 1992, issue of Science (GLOBAL CLIMATE CHANGE DIGEST, Prof. Pubs./Gen. Interest, Feb. 1992), may help explain why the Earth has so far warmed less from greenhouse gases than predicted by models.

The panel also accepted recent results indicating that the greenhouse warming effect of CFCs is offset by the degree to which they thin the stratospheric ozone layer (GLOBAL CLIMATE CHANGE DIGEST, News, Dec. 1991), and concluded that the role of methane in global warming may be somewhat less than previously thought. Calculations of global warming potentials were revised, and several more reference scenarios developed. The report was authorized by the full IPCC at a January meeting in Geneva, and constitutes part of the IPCC contribution to the climate treaty negotiations in progress. Contact the World Meteorological Organization, POB 5, 1211 Geneva 2, Switz.

See Science, pp. 682-683, Feb. 7, 1992 (includes discussion of the history of research on the cooling effects of aerosols); New Scientist, p. 17, Jan. 25; Global Environ. Change Rep., p. 5, Jan. 31; Intl. Environ. Rptr., p. 35, Jan. 29.