Climate change is the largest environmental threat facing humans and other species that inhabit planet Earth. We are increasingly aware of the causes, impacts, and likelihood of climate change. Yet, recent international meetings on climate change suggest that the nations (and people) of the world are unwilling to take actions on the scale and timeline that most scientists say is needed to avoid the most severe impacts of climate change. In short, the demand for climate action implied by most scientific evidence has not yet been matched by the supply of action from political leaders, policy-makers, and the public.