Swap Painful People for Peaceful Productive Trees

If the nastiest and greediest 50% (irrespective of demographics) of the world's population suddenly turned into trees (working on that one), the cities would turn into forests, the oppressed would be free (instead of abused), the starving would have food, the wild would have homes, and the world would be saved from certain enviromental doom! Yey! Sure, some remaining people would be sad, but they would get distracted by something rare, beautiful and liberated and recover. I'm just going to one of my happy fairytale places here.