Predictions of climate changes caused by man-made emissions of greenhouse gases: A critical assessment

Abstract

Abstract Predictions of the most advanced computer models of the changes in the global climate that may result from man-made emissions of greenhouse gases are described and assessed in the light of the uncertainties in future emissions and atmospheric concentrations of these gases, and of the limitations of the models Predictions of the globally averaged temperature rise, produced by the doubling of atmospheric carbon dioxide over 70 years, range from 1·3 to 2·6°C, on average about 0·3°C decade−1. The scattering of solar radiation by atmospheric aerosols is calculated to reduce this global warming to about 1·0°C or 0·2°C decade−1. Warming is predicted to occur everywhere but to be most marked in high latitudes of the Northern Hemisphere. Globally averaged precipitation is predicted to rise by a few per cent but with large geographical variations and areas of both increase and decrease. The largest increases are expected to occur in intertropical convergence zone, and in middle and high latitudes, especially in winter. Decreases are predicted in the subtropics. The best current estimate of the rise in sea level resulting from an annual increase of 1% p.a. of carbon dioxide is 4 cm decade−1.