A Green Planet versus a Desert World: Estimating the Effect of Vegetation Extremes on the Atmosphere

Abstract

The effect of vegetation extremes on the general circulation is estimated by two atmospheric GCM simulations using global desert and forest boundary conditions over land. The difference between the climates of a ?green planet? and a ?desert world? is dominated by the changes of the hydrological cycle, which is intensified substantially. Enhanced evapotranspiration over land reduces the near-surface temperatures; enhanced precipitation leads to a warmer mid- and upper troposphere extending from the subtropics (induced by ITCZ, monsoon, and Hadley cell dynamics) to the midlatitudes (over the cyclogenesis area of Northern Hemisphere storm tracks). These regional changes of the surface water and energy balances, and of the atmospheric circulation, have potential impact on the ocean and the atmospheric greenhouse.