Because tropical forests absorb so much carbon dioxide, they're one of the best antidotes to climate change, but there's a catch. Heat stress and drought kill trees, releasing their stored carbon back into the atmosphere. A new study suggests that if warming reaches 2°C above preindustrial levels, vast portions of tropical forests will begin to lose more carbon than they take in. However, associate energy and resources professor Lara Kueppers is concerned that the study might be too optimistic in forecasting that cooler forests, especially in Asia and Africa, will continue to absorb large amounts of carbon as they warm. She says it's not certain that those forests will behave the way ones in South America have, or that they can adapt to the speed of human-induced climate change. "I don't have confidence that forests are going to be able to adjust on the time scale they will need to," she says.