No country can save its own climate system, because greenhouse gas pollution and climate impacts do not respect borders. If we are to stabilize the climate, we need every country to do its proper part, and by so doing move others to take their own action. Rich and powerful countries, in particular, must do their fair share if we are to have a real chance at fixing the climate crisis. The US is certainly among them.
Climate change is the greatest collective crisis the world has ever confronted, and overcoming it will require unprecedented global cooperation. This kind of cooperation will simply not be possible if countries – especially rich and powerful countries like the United States – are not seen to be doing their fair share. This must include supporting action in poorer countries, in addition to drastically reducing emissions within their own borders. In the IPCC’s measured words: “Outcomes seen as equitable can lead to more effective cooperation.”
 Summary for policymakers. In Climate change 2014: Mitigation of climate change. Contribution of Working Group III to the Fifth Assessment Report of the IPCC. O. Edenhofer et al. (eds.) Cambridge University Press, Cambridge, UK, and New York. https://www.ipcc.ch/report/ar5/wg3/