Tracking tropical deforestation impacts on local and regional hydroclimate

Tropical regions have undergone extensive deforestation in recent decades, significantly impacting local, regional, and global water cycles; however, detailed studies on their hydroclimatic effects remain limited. This study employs a regional climate model coupled with a water vapor tracking tool to investigate the effects of deforestation on local and regional precipitation from 2000 to 2020 in three major tropical deforestation hotspots: the Amazon, Africa, and Southeast Asia. Results indicate that deforestation affects precipitation with distinct scale-dependent and seasonal variations. In the Amazon, contrasting precipitation responses to deforestation were observed between wet and dry seasons (Yingzuo Qin et al., Nature, 2025, in press). During the wet season, deforested areas exhibited a notable increase in precipitation (0.96 mm month^-1 per percentage point of forest loss), primarily due to enhanced mesoscale atmospheric circulation (i.e., nonlocal effects). These nonlocal effects weakened with distance from deforested areas, resulting in significant precipitation reductions beyond 60 km. Conversely, during the dry season, precipitation decreased in deforested areas and across all analysis buffers, with local effects from reduced evapotranspiration (ET) dominating. In Africa, due to the dispersibility of deforestation across the continent, the scale-dependency and seasonality of precipitation effects caused by deforestation are influenced by elevation and deforestation patch size. In Southeast Asia, under the strong influence of oceanic water vapor, deforestation-induced positive precipitation effects prevail throughout the year. These findings underscore the complex interplay between local and nonlocal effects in driving tropical deforestation-precipitation responses across different seasons and scales, highlighting the urgent need to address the rapid and extensive loss of forests in tropical regions to mitigate their nonnegligible climatic impacts.