This is a bad faith argument. You are arguing the efficiency of a country based upon its CO2 per GDP. That's kind of a shit argument because GDP is a human construct. Global warming doesn't give a shit about GDP.
How much "value" a country produces based upon...what, exactly? How much it extracts from the ground? How much value other humans assign to those goods?
Capitalism got us into this fucking mess and you're still using it as the goddamn ruler.
If you want to compare states, fine, I guess that works as a proxy for cultural differences, but if you are going to compare the efficiency of the people within the state, you measure per capita.
Using GDP is just a shit excuse to be able to defend capitalism while simultaneously dismissing the fact that China supports more people with fewer per-capita emissions.