Tuesday, February 7, 2012

Human Domination of Earth's Ecosystems

by Peter M. Vitousek, Harold A Mooney, Jane Lubchenco, Jerry M. Melillo
Science. Vol. 277. July 25, 1997.

Biotic Changes
Human modification of Earth's biological resources- its species and genetically distinct populations- is substantial and growing. Extinction is a natural process, but the current rate of loss of genetic variability, of populations, and of species is far above background rates; it is ongoing; and it represents a wholly irreversible global change. At the same time, human transport of species around Earth is homogenizing Earth's biota, introducing many species into new areas where they can both disrupt both natural and human systems.
Losses. Rates of extinction are difficult to determine globally, in party because the majority of species on Earth have not yet been identified. Nevertheless, recent calculations suggest that rates of species extinctions are now on the order of 100 to 1000 times those before humanity's dominance of Earth. For particular well-known groups, rates of loss are even greater; as many as one-quarter of Earth's bird species have been driven into extinction by human activities over the past two millennia, particularly on oceanic islands. At present, 11% of the remaining birds, 18% of the mammals, 5% of fish, and 8% of plant species on Earth are threatened with extinction.

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