I must agree with Joe here, I feel we have a efficiency problem, not a population problem. At least not yet.

I think the way humans live is whats causing problems, if those problems can be solved. Earth can sustain 100 times its current population while leaving room for wildlife.

I see this development the same as computers. The first computer filled a room, Today it is as big as a book and 1000 times better.

But then we assume that humans will change, so for now, ironically I feel there's too many humans on earth. Speaking from a nature perspective. Not trying to promote genocide here...