Biogeophysical versus biogeochemical feedbacks of large-scale land cover change

Large-scale changes in land cover affect nearsurface energy, moisture and m omentum fluxes owing to changes in surface structure (referred to as biogeo physical effects) and the atmospheric CO2 concentration owing to changes in biomass (biogeochemical effects). Here we quantify the relative magnitude of these processes as well as their synergisms by using a coupled atmospher e-biosphere-ocean model of intermediate complexity. Our sensitivity studies show that tropical deforestation tends to warm the planet because the incr ease in atmospheric CO2 and hence, atmospheric radiation, outweighs the bio geophysical effects. In mid and high northern latitudes, however, biogeophy sical processes, mainly the snow-vegetation-albedo feedback through its syn ergism with the sea-ice-albedo feedback, win over biogeochemical processes, thereby eventually leading to a global cooling in the case of deforestatio n and to a global warming, in the case of afforestation.