Tropical forests and global warming: slowing it down or speeding it up?

Abstract

The world's tropical forests take up and emit large amounts of carbon (C) through photosynthesis and respiration. Their response to global changes in the atmosphere and climate could therefore act as a feedback. Only recently has research been focused on the possibility that tropical forests may not be in C balance. There is currently a vigorous debate about whether these ecosystems might be accelerating or slowing down the rate of atmospheric CO2 accumulation, and thus global warming. The evidence is thin in either direction, and in some cases highly uncertain. Some findings raise the possibility that higher temperatures could make tropical forests increasing C sources to the atmosphere – a positive feedback effect. To project where our climate is headed, it is critical to resolve two questions: how tropical forests are reacting to changing climate, atmosphere, and land use, and how they will continue to respond over the coming decades.