A statistical study of the regional impact of deforestation on climate in the LMD GCM

The present study uses the general circulation model of the Laboratoire de Météorologie Dynamique (LMD-GCM) coupled to the land-surface, vegetation model SECHIBA. The impact of deforestation on climate is discussed. Replacing tropical forests by degraded pastures changes albedo, the roughness length and the hydrological properties of the surface. The experiment was carried out over eleven years using the observed sea surface temperature from 1978 to 1988, which includes two major El Niño events. The discussion of the results in this study is limited to the regional impact of deforestation. The changes found for the surface fluxes in Amazonia, Africa and Indonesia are examined in detail and compared in order to understand the impact on temperature. Special attention is paid to feedback mechanisms which compensate for the surface changes and to the statistical significance of these results within the tropical variability of climate. It is shown that the relatively small regional impact of deforestation in this study is statistically significant and largely independent of the El Niño-Southern Oscillation phenomenon.This paper was presented at the Second International Conference on Modelling of Global Climate Change and Variability (Hamburg, September 1992)