I really don't see how this would be a good idea. First of all it suggests that wealth is the be-all and end-all of human progress. It also implies that wealth

I really don't see how this would be a good idea. First of all it suggests that wealth is the be-all and end-all of human progress. It also implies that wealth creation is equivalent wherever it happens - that somehow if a place is more efficient at creating wealth than it should be privileged. Finally, of course, this means that poorer countries that produce less wealth will almost certainly be less efficient by this metric, and hence should be penalized (of course, we shouldn't mention that a lot of their production actually ends up being consumed by the rich-world which can this way claim to be highly CO2 efficient).