Point is more that if a successful separatist movement in China, which just redraws borders without closing any power plants, is all it takes to turn that reaso

Point is more that if a successful separatist movement in China, which just redraws borders without closing any power plants, is all it takes to turn that reasoning into "we need to do something about USA", then it seems like a wonky measurement. A measurement that says China is the problem but not Huabei, Dongbei, Huadong, Zhongnan, Xinan, or Xibei, is wonky. A measurement that says the EU emits too much carbon but France, Germany, Italy, Spain, Greece, and Poland don't, is also wonky. If you start from a premise that each human has an equal right to emit carbon as any other, regardless of which country they're born in, then you naturally get per-capita measures as a result. An absolute measure implies that each country has an equal right to emit carbon, but since countries are fluid and artificial constructs, that results in some pretty weird consequences, like each person in Britain being allowed to burn more gasoline if Scotland leaves the UK. Growing up in times of stability it might seem like countries are concrete and unchangeable, but borders move and countries appear and disappear all the time, and an international law that only applied to the top emitter would likely be enough pressure to cause that country to redefine itself as an informal federation of multiple states.