Abstract
Recent studies on the Amazon deforestation problem predict that removal of the forest will result in a higher surface temperature, a significant reduction in evaporation and precipitation, and possibly significant changes in the tropical circulation. Here, we discuss the basic mechanisms contributing to the response of the tropical atmosphere to deforestation. A simple linear model of the tropical atmosphere is used in studying the effects of deforestation on climate. It is suggested that the impact of largeβscale deforestation on the circulation of the tropical atmosphere consists of two components: the response of the tropical circulation to the negative change in precipitation (heating), and the response of the same circulation to the positive change in surface temperature. Owing to their different signs, the changes in predicted temperature and precipitation excite competing responses working in opposite directions.
The predicted changes in tropical circulation determines the change, if any, in atmospheric moisture convergence, which is equivalent to the change in runβoff. The dependence of runβoff predictions on the relative magnitudes of the predicted changes in precipitation and surface temperature implies that the predictions about runβoff are highly sensitive, which explains, at least partly, the disagreement between the different models concerning the sign of the predicted change in Amazonian runβoff.