The world is badly overpopulated, and if I could press a button that would bring the pop down to 500 MM, eliminating all of china, russia, africa, the mideast (except Israel), and south america, I'd hit that button with a hammer.
I have given this a lot of thought over the years, and the maximum amount of people the world could sustain if everyone was producing the same amount of pollutants and using the same amount of resources like water as an american, would be about 500 MM.
The world is headed towards a disaster seen in the movies Elysium/Soylent Green, etc; overcrowded, polluted, starving masses, etc. The africans and the rest of the 3rd world needs to start using birth control.
It is not the responsibility of the 1st world to be the 3rd world's safety valve for its overpopulation, nor is it to come up with ways to cure its diseases (like AIDS) that spring up in various 3rd world shitholes that would helpt to reduce the pop of these areas as they should.