A big problem is the international aspect and the requirement for what effectively are wealth transfers. Countries often are willing to bribe part of the voter

A big problem is the international aspect and the requirement for what effectively are wealth transfers. Countries often are willing to bribe part of the voters to make some universal policies tolerable, having internal transfer payments for the benefit of the country as a whole. The world is (IMHO clearly) very, very limited in its willingness to bribe part of foreign voters to make some global policies tolerable, having international transfer payments for the benefit of the world as a whole. There are some examples, but they're very limited in scale compared to intra-country wealth transfers. It's plausible to convince voters for some reallocation between themselves, even if many specific voters would not individually benefit - but it's a hard sell to convince voters to assign significant resources (as opposed to current international aid/charity) to primarily benefit people in another country, which IMHO seems to be necessary because there's so big country-to-country variation in the actions needed to reduce global warming, the ability to afford these actions, and the severity of local consequences of global warming.