Albedo change by man: test of climatic effects

Abstract

Sagan et al.¹ have suggested that the cumulative impact of anthropogenic albedo changes may have contributed to global climate changes in the past and that its effect may be continuing. Using a statistical dynamic climate model (SDM) with more realistic surface albedo changes than previously used², we have computed the combined impact of desertification of the Sahara and deforestation of the tropical rain forest. While the model computed a surface cooling of 0.6 K for the Northern Hemisphere, the global mean of ∼0.2 K was substantially less than the 1 K suggested by Sagan et al.¹. We infer that man's cumulative impact on planetary surface albedo over the past few thousand years has had a small and probably undetectable effect on global climate.