Solution to save the environment: China should separate out Tibet, Xinjiang, and Inner Mongolia as separate independent countries. Hong Kong and Macao too. And then split north-south so that Shanghai and Beijing become their own capitals. Continue this process and eventually the population and emissions of each individual country will be low enough that they can be ignored, thus solving the problem once and for all.

That is the opposite of what GP said. The point is only the total emissions matter, the climate does not care about "fair" allocations over either people or nation-states.