Surface Warming and Atmospheric Circulation Dominate Rainfall Changes Over Tropical Rainforests Under Global Warming

This study investigates how the direct effects of CO2 quadrupling on plant physiology impact precipitation in three main rainforests. We show that differences between the regions lie in how land-surface warming (driven by reduced transpiration) interacts with their climatological atmospheric circulations, regardless of their reliance on evapotranspiration. Various atmosphere-only experiments from two General Circulation Models are used. We find that over New Guinea, land-surface warming amplifies moisture convergence from the ocean and increases rainfall. In the Congo, no clear rainfall changes emerge as the land-surface warming effect is offset by migrations of rainfall. In Amazonia, the interaction of land-surface warming with the climatological circulation pattern leads to a precipitation-change dipole, with reduced rainfall in central and eastern Amazonia and increased rainfall in the west.