Extinction level event

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An extinction level event (ELE) is an event where the majority of species on the planet become extinct. This is opposed to normal extinctions of just single species, which happen all the time in the wild, at a background extinction rate. Things that cause extinction level events include supervolcanoes and mass climate change, which are events suspected to have happened in the past on several occasions. The most spectacular, of course, are asteroid impacts — which were popularized in the late 1990s by the movies Deep Impact and Armageddon.

Historical extinction level events[edit]

The most famous — undoubtedly because it is among the most spectacular — historical extinction would be the asteroid impact that killed off the dinosaurs (the K-Pg boundaryWikipedia) 65 million years ago.

However, this pales in magnitude compared to the P-T extinctionWikipedia event, which ended the Permian period 252 million years ago. Also known as the Permian mass extinction or the "Great Dying", it resulted in the worldwide loss of 57% of all families, 83% of all genera, 96% of all marine species, and an estimated 70% of all land species. Its cause is unclear but may have involved gradual climate change made suddenly much worse by meteor impact or volcanoes.[1]

Similar explanations are suggested for the Triassic–Jurassic extinction eventWikipedia around 201 million years ago.

The Late Devonian extinctionWikipedia 360-375 million years ago only affected aquatic life; again its causes are unclear but oxygen levels in water seem to have dropped dramatically.

Finally, the extinction which is understood most clearly is happening now, the Holocene extinctionWikipedia. The cause: people killing animals and plants—as much by habitat loss and climate change as by overhunting.

Plausible causes[edit]

It's generally hard to figure out what happened last night, let alone 300 million years ago. Explanations vary but the following mechanisms have been advanced for past extinction events:

Implausible causes[edit]

See also[edit]