"Some of the harm that humans cause to other humans and to animals is mediated by the destructive effect that humans have on the environment. For much of human history, the damage was local. Groups of humans fouled their immediate environment. In recent centuries the human impact has increased exponentially and the threat is now to the global environment. The increased threat is a product of two interacting factors–the exponential growth of the human population combined with significant increases in negative effects per capita. The latter is the result of industrialization and increased consumption."