From Envirowiki

Extinction is the complete loss of an entire species of life. Extinction is permanent, and usually the vast majority of the information (genetic code) that the species containted is lost as well. Extinction is a permanent loss of biodiversity.

[edit] 1 Causes

Some extinction happens naturally, due to natural climate changes, or biogeographical changes (e.g. other species moving in to a region from somewhere else). However, these changes usually occur very slowly, and infrequently. The exception is that past mass extinction events in the earth history, in which large majorities of the earth's species were wiped out.

[edit] 1.1 Human-caused extinction

Humans have caused numerous species extinctions. In the past, the has been mostly due to over hunting and over fishing, and more recently due to land colonisation for development.

Now, extinctions from anthropogenic climate change is beginning to occur, one well known example being the Golden Toad, from the Amazon. Species will continue to become extinct due to climate change, until we manage to curb our emissions. Species at risk of extinction from climate change could be as much as 50% by 2050, under a BAU scenario^[1].

[edit] 2 References

1. ↑ Thomas, Chris D.; Alison Cameron, Rhys E. Green, Michel Bakkenes, Linda J. Beaumont, Yvonne C. Collingham, Barend F. N. Erasmus, Marinez Ferreira de Siqueira, Alan Grainger, Lee Hannah, Lesley Hughes, Brian Huntley, Albert S. van Jaarsveld, Guy F. Midgley, Lera Miles, Miguel A. Ortega-Huerta, A. Townsend Peterson, Oliver L. Phillips, Stephen E. Williams (2004-01-08). "Extinction risk from climate change". Nature 427 (6970): 145-148. DOI:10.1038/nature02121. Retrieved on 2008-08-18.