Blog #5 Causes of Extinction

The five major extinction events in history was the mass extinction that took place at the end of the Ordovician where 60% of both terrestrial and marine life worldwide became extinct. In the late Devonian period enviorments that had nurtured reefs for a long time turned bad and the world once again fell in to a second mass extinction. The Permian mass extinction showed about 80-95% of marine species went extinct and the reefs didnt appear for millions of years. In the Triassic mass extinction about half of the marine invertbrates went extinct and 80% of land quadrupeds went extinct. Futhermore, in the end of the Cretaceous mass extinction 65 million years ago caused the widely know extinction of dinosaurs. Not only that almost on large land animals survived and plants where also affected. Now it seems humans are causing the 6 great mass extinction. It is because of the growing population of humans that are pushing some species into enviorments they aren't adapted to causing them to be hunted and eventually becoming extinct. Besides that the main cause is the changing climate which is caused my humans waste products and green house gases or known as global warming. With global warming the ice caps are melting which will eventually cause the sea level to rise like in the 5 mass extinction when sea level rised and many land animals went extinct.

 http://www.skepticalscience.com/Earths-five-mass-extinction-events.html

http://news.yahoo.com/s/livescience/20110303/sc_livescience/humansonvergeofcausing6thgreatmassextinction