Yet biodiversity is now threatened by a wave of extinction unparalleled since dinosaurs became extinct 65 million years ago. The Environmental Protection Agency's independent Science Advisory Board in 1990 identified habitat loss and species extinction as two of the four most critical global environmental problems. The tangible benefits to humanity of plants and wildlife are numerous. Humans rely on the natural world for food and new curative drugs. Wildlife and ecosystem-based tourism is a source of economic growth.
Ecosystems sustain natural processes such as soil creation and the oxygenation of air and water.
Continued rapid loss of biodiversity eventually would disrupt essential natural processes on which human survival depends. In addition, the emotional benefits to humans of biodiversity cannot be overstated. As part of the natural world, humans feel a powerful affinity for and connection to that world. As habitats are paved over, burned or developed, people feel increasingly disconnected from that world and many feel a corresponding sense of loss. Finally, humans are trustees of the environment for future generations and have an ethical obligation to protect that environment.