[ant6n]

What matters is per capita emissions, not some arbitrary measure based on how borders happen to have been drawn hundreds of years ago. A small country like Kuwait, or the US (relative to China) cant just pretend not to be part of the problem, because they can point at some region with more people that consequently have larger emissions.

And historical emissions are relevant, since the carbon budget relates to the total amount of co2 in the air above pre-industrial levels. That co2 budget was largely "spent" by the US.