Overpopulation
The world's population may eventually reach a level where there will not be enough resources to sustain life as we know it. Growth must be checked to avoid this catastrophe. Many environmental, social, and economic problems either stem from or are increased in magnitude by the overpopulation problem.
Resource Depletion
As the world’s population grows unsustainably, so do its unyielding demands for water, land, trees and fossil fuels — all of which come at a steep price for already endangered plants and animals. Species are disappearing about 1,000 times faster than is typical of the planet’s history. This time, though, it isn’t because of geologic or cosmic forces but unsustainable human population growth.
Biodiversity
Biodiversity boosts ecosystem productivity where each species, no matter how small, all have an important role to play. For example, a larger number of plant species means a greater variety of crops; greater species diversity ensures natural sustainability for all life forms; and healthy ecosystems can better withstand and recover from a variety of disasters. And so, while we dominate this planet, we still need to preserve the diversity in wildlife.