There are currently 7 billion people. A billion of them are starving, many are homeless and disease is spreading because of this. The human population is rising at an exponential rate and soon the Earth won’t be able to support us. Overpopulation aggravates resource depletion. We rely on fossil fuels for transportation and minerals for manufacture. These resources are finite. The United Nations says that if fertility levels remain unchanged at today's levels, world population will rise to 44 billion in 2100, according to the U.N. - http://www.un.org/apps/news/story.asp?NewsID=12439
http://youtu.be/nGeXdv-uPaw