Given that tropical forest degradation causes greenhouse gas emissions similar in quantity to those from deforestation, switching from degradation to responsible forest management could mitigate global warming while protecting biodiversity and contributing to sustainable development. Unfortunately, the international debates leading to a post-Kyoto climate change agreement focus mostly on deforestation rather than on forest degradation. Worse yet, unless safeguards are in place, continued use of the Kyoto Protocol’s definition of ‘forest’ could inadvertently accelerate forest degradation in developing countries, jeopardize critical biodiversity, and interrupt the flow of ecosystem services. There is clearly a need for a new definition of forest as well as for inclusion of forest degradation in the new global climate change agreements.