Simulated climate effects of Southeast Asian deforestation: Regional processes and teleconnection mechanisms

A coupled atmosphere-ocean model is used to examine the climatic effects of Southeast Asian deforestation. On the deforested grid cells surface temperatures rise, and precipitation is reduced after deforestation. Regional moisture convergence and convection increase and lead to strongly enhanced rainfall. The easterlies and associated oceanic surface currents are reduced in the Southeast Asian realm. As a result, the upwelling of cold ocean water weakens, and surface temperatures rise. This acts as a strong positive feedback mechanism for the enhanced regional moisture convergence. Besides the regional effects, we find strong teleconnections to the tropics and to the high latitudes of both hemispheres. The signal from Southeast Asia propagates to the extratropics with the high-level winds in the form of sensible heat and potential energy. Possibly because of strong albedo-sea ice feedbacks, some regions in the high latitudes amplify relatively small initial climate changes and exhibit strong remote effects. The excitation of atmospheric waves (probably Rossby waves) is the underlying mechanism that causes the signal propagation to the extratropics.