The problem with thinking the UN can enforce the kinds of things that are being suggested is that the UN is only made up of its member nations. If the member nations don't want any particular policy to be agreed upon, they won't agree on it. And worse, the UN is not a democracy. The UN has a few very powerful players who essentially call all the shots while most of the countries don't really have any say. It's not possible for the UN to do anything other than enforce the will of the most powerful nations. And even if it were a democracy, and all of the member nations had the same amount of say, there's no way the member nations would ever agree to the sort of thing that is being proposed in this thread.