The means would initially be similar to those used against other mildly-rogue regimes such those of Serbia and Mali: withdrawal of cooperation, fines, and limit

The means would initially be similar to those used against other mildly-rogue regimes such those of Serbia and Mali: withdrawal of cooperation, fines, and limited sanctions. If we get to the late 2040s and the rest of the world is within touching distance of net zero but the US remains as an extreme outlier in its refusal to decarbonise, then we could well see harsher measures such as those applied to the likes of Russia and Venezuela.