Late twentieth-century patterns and trends in the climate of tropical forest regions

Abstract

Abstract This chapter presents an analysis of the mean climate and climatic trends of tropical rainforest regions over the period 1960-98, with the aid of climatological databases. Since the mid-1970s all tropical rainforest regions have experienced a warming, in synchrony with a global rise in temperature that has been attributed to the anthropogenic greenhouse effect. Over the study period precipitation appears to have declined sharply in northern tropical Africa, declined marginally in tropical Asia, and showed no significant trend in Amazonia. There is no evidence to date of a decline in precipitation in eastern Amazonia, a region thought vulnerable to climate-change induced drying. The strong drying trend in Africa suggests that this should be a priority study region for understanding the impact of drought on tropical rainforests. Only African and Indian tropical rainforests appear to have seen a significant increase in dry season intensity. The El Niñno-Southern Oscillation is the primary driver of interannual temperature variations across the tropics, and of precipitation fluctuations for large areas of the Americas and Southeast Asia.