The social sciences—from psychology to sociology, from economics to geography, from anthropology to political science—are now essential to meeting the climate challenge. This in no way discounts the critical value of the natural sciences in their continued quest to understand how the climate system works and has changed over time, and the causes, consequences, and potential solutions to anthropogenic climate change. It does, however, challenge the social scientiﬁc community to more fully engage this and other global sustainability challenges. Perhaps more importantly, it challenges the funding community to provide the necessary and sustained levels of support this research requires—to both understand the dynamics of coupled human and natural systems and to develop the ‘‘sustainability science’’ that can inform societal decision making (Kates et al. 2001). And it challenges all of us to continue the effort to bridge the divide between the natural and social sciences—and yes, the humanities too—in the effort to understand and solve our shared global challenges.