The future of climate change is largely about China and India. Their populations are gigantic, their economies are growing fast, and their potential emissions growth could completely swamp anything else that happens in the world. The United States must act as well, but as I've argued before, it's mainly in the service of obtaining an international climate agreement. Therefore, choices that policymakers in those countries make today will have enormous climate effects over the next few decades. New coal-fired power plants, for instance, will last for many years, and it will be hard to avoid using them. But should these nations manage to leapfrog the traditional fossil fuel-driven stage of the economic growth path, the climate benefits could be enormous.