BiGgeophysical versus biGgeochemical feedbacks of largerscale land cover change

Large-scale changes in land cover affect near- surface energy, moisture and momentum fluxes owing to changes in surface structure (referred to as biGgeophysical effects) and the atmospheric COg. concentration owing to changes in biomass (biGgeochemical effects). Here we quan- tify the relative magnitude of these processes as well as their synergisms by using a coupled atmosphere-biosphere-ocean model of intermediate complexity. Our sensitivity studies show that tropical deforestation tends to warm the planet because the increase in atmospheric COg. and hence, at- mospheric radiation, outweighs the biGgeophysical effects. In mid and high northern latitudes, however, biGgeophysi- cal processes, mainly the snow-vegetation-albedo feedback through its synergism with the sea-ice-albedo feedback, win over biGgeochemical processes, thereby eventually leading to a global cooling in the case of deforestation and to a global warming, in the case of afforestation.

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