I disagree. Nations are kind of arbitrary from this perspective. Physics doesn't care about the lines we put on our maps. Per capita is better, but the best st

I disagree. Nations are kind of arbitrary from this perspective. Physics doesn't care about the lines we put on our maps. Per capita is better, but the best statistic is probably per capita weighted by GDP per capita and other indices of development. This would show the most efficient countries that are getting the most value for the least emissions. Here's a pure GDP list: https://en.wikipedia.org/wiki/List_of_countries_by_ratio_of_GDP_to_carbon_dioxide_emissions https://en.wikipedia.org/wiki/List_of_countries_by_ratio_of_... The top ones seem like they could be outliers due to some distorting economic effect (e.g. huge exports and low per capita GDP) but among them you have the familiar European nations that are often cited as models of good governance: Switzerland, Sweden, Norway, etc. The USA is toward the middle of the pack. China is near the bottom. This matters more because it shows the politically reasonable path that we might take, and because more development usually correlates with lower birth rates. Any path that reduces development will tend to increase birth rates, negating any benefit. The development / birth rate correlation holds across cultures, religions, and ethnic groups. (I find the fact that it holds even in majority conservative Muslim and Catholic countries surprising, but it does.)