For many years China and the United States have faced off over climate change. Now, action is one of the few things the two powers can agree on. A new view on the benefits of climate action goes some way to explain this shift. Since the start of international climate negotiations, China has insisted that rich countries must act first to cut emissions and should pay for the costs of emissions reductions in China and other developing countries. Meanwhile, the United States has insisted that China and other developing countries must be part of action on climate change and used China’s apparent inaction to excuse their own.