Effects of deforestation at different spatial scales on the climate of the Amazon basin

Abstract

Deforestation in the Amazon has accelerated in recent years, making it increasingly important to understand the physical processes that occur after forest removal. This study investigates how deforestation at different spatial scales alters the climate in the Amazon. Using the Eta regional climate model, 3 deforestation scenarios were simulated: a scenario with the Amazon basin totally covered by forest (FLOR); a second scenario with projected deforestation for the year 2050 (DF50); and a third scenario in which the Amazon forest is entirely replaced by degraded pasture (DFTOT). The results show that both deforestation scenarios caused a reduction in precipitation (0.10 mm d-1 for DF50 and 0.35 mm d-1 for DFTOT during the wet season), due mainly to reduced evapotranspiration in the forest (0.28 mm d-1 for DF50 and 0.96 mm d-1 for DFTOT during the wet season). Despite the increase in moisture flux convergence, it was not sufficient to increase the precipitation in the region. Deforestation resulted in increased upward motion in the lower troposphere, creating a potentially more convective environment, but not enough to produce more cloudiness and precipitation over the Amazon basin. Regardless of the considered deforestation scenario, significant changes were observed in radiation, energy and water balances, atmospheric conditions, and convective potential across much of the Amazon basin during the dry and wet seasons. However, the most significant impacts occur in scenarios of complete deforestation, indicating a direct relationship between the spatial scale of deforestation and the impact on regional climate.