Vulnerability of the tropics to future changes in drought and fire

In the future, changes in precipitation across the tropics may have profound consequences for the survival of tropical forests and their vulnerability to fire and other agents of global change. I will discuss how the physiological response of forests to increasing CO2 is a primary mechanism responsible for this pattern, drawing upon simulations from the Community Earth System Model. Using an experimental design in which CO2 increases were isolated over individual continents, I will discuss how contrasting regional circulation and rainfall responses emerge from a mostly uniform forcing caused by decreasing canopy transpiration. These simulations indicate that the sum of local responses over individual continents mostly explains the pan-tropical precipitation asymmetry, and suggest that forests in South America may be more vulnerable to rising CO2 than forests in Asia or Africa.