People often think there are space issues, but the entire 7 billilion people that live on the earth could fit in California in "concert conditions".

Energy is usually a big problem. In the fight for equality more and more energy is needed so people don't lose what they already have, even though there are few solutions to getting such energy quickly and safely. In un developed countries there is little to no amounts of energy which is the opposite of what we have in this country.

Wildlife is also at stake. The more of people there are, the fewer of other animals and species(except for animals that humans keep such as pets and farm animals). Even in some areas in Africa where there is a lot of wildlife.

More problems...