China’s expanding economic wealth brings into focus a critical dilemma facing all states within the international system: how to increase economic prosperity at a time when the world is struggling to provide food, water, and energy to an expanding population that is increasingly urbanized. The resource scarcity problem is further exacerbated by the onset of disruptive climate change that underscores the urgency of taking action now in order to avert major catastrophes in the future. As recognized by the United Nations Secretary General Ban Ki-Moon, climate change is “the deﬁ ning challenge of our age.” We have already reached a political tipping point at which the opportunity to reverse the upward trend in emissions growth is likely to recede over time. But it remains to be seen whether a growing sense of vulnerability will be sufﬁ cient to galvanize states into taking action. Leadership on climate change is currently in a state of ﬂ ux, in part a reﬂ ection of uncertainty over China’s future contribution.