If you ever took biology you've probably heared about "carrying capacity", how big a population can the ecosystem take. Well, how many humans can our earth carry?
This film is quite frightening, well worth watching.
(swedish) check out David Attenborough on youtube, plenty of videos...
Start thinking about ones consumer habits, water, electricity and food consumption. 1.2 billion people lack water at the moment, how will we sustain another 2 million, oh sorry Billion, people with clean water?