A World Governed by the UN would be like John Travolta’s movie Battlefield Earth (2000) ,LOL
It won’t be the UN. It will be a confederation of regional governments. The EU, the NAU, etc., with Russia and Red China remaining major independent players.
The have defeated their major opponent (America)
Instead of worrying about the earth, how about they worry about the people on the earth that are being murdered and oppressed.