Yes, that's what's been happening but it's exactly what I'd call "just-sort-of-happened without informed consent of the masses" - which is sustainable only while the costs are relatively trivial. If the impact grows, it will have to devolve to one of the three scenarios; the EU core institutions are composed of country's prime ministers and of directly elected representatives - all of those could and would be held accountable as soon as the people started to be bothered enough about the EU-wide decisions; currently they mostly vote for local parties based on their local issues, but if (when?) climate change and various options for tackling it (or not) would become an important issue in elections, then the same parties will put their EU-level votes as a key part of their election agenda.