how would you improve the world?
First I would unleash a devastating disease that would primarily afflict people who lack good hygiene. This would wipe out most of the dead weight from the planet, and hopefully collapse the global economy.
After that I'd near irreparably destroy the mechanisms through which fossil fuels are extracted and used at our convenience, setting civilization back significantly.
Finally, I'd kill everyone with an IQ below 100, and sterilize those that remain who carry genetic abnormalities. Implement a breeding program for the survivors of this culling that would force racemixing over 3-4 generations, resulting in a unified, strong, intelligent human race without any of the problems that come with ethnic differences.
As an addendum, I would also rid the world of mosquitoes. I do not care about their value to the ecosystem.