The best measure for personal responsibility, but arguably the worst for actually doing a damn thing to solve the problem. Sparsely populated or isolated countries contribute little of the total while scoring high per individual.
Qatar per capital co2 is something like 900% of the global average, but they emit 0.3% of the world's total. Meanwhile, India is a well behaved and below average 40% per capita emitter while being the third largest emitter at 7.6% of the total.
Palau is the undisputed per capita king at almost 1300% of global average. But at 0.004% net, they could disappear tomorrow and not change things at all.
So if you want to actually change the trajectory, per capita is a red herring. You address the net offenders first. Sure, everybody should pitch in, but where you spend your outrage capital matters. It only serves to let some folks feel righteous indignation.