You can’t legally bind a country. You can shame it. You can penalize it. You can blockade it. You can go to war with it, but there is no court that actually has binding jurisdiction over a country, that can make its courts and government comply.
The main purpose in setting goals in law is to enable every Tom, Dick and Harry environmentalist to sue that nation and tie up any environmental retrenchment in civil and criminal courts until the country gives up and pretends to follow the “law”. The worse thing about the US environmental laws is their enshrining legal standing for kooks and their lawfare allies.