I would heal the barren wastes across the earth. Maybe if people had more idyllic gardens of Peace, Love and Happiness, they'd leave each other the hell alone. It'd probably due quite a bit to fix that whole *world hunger* thing, too.
After proving my divinity with this wondrous event, I'd institute a new morality system based around treating other people well. You know, just being a nice person. This would be a big improvement over, "treat people well who are nearly identical to myself and treat everybody else like shit".
I'd probably renew the resources of nations who generally play nice whilst raining bastarditude down on everybody else. Fear my wrath. I am that I am.