Editing Extinction event (section)

====Global cooling====
Sustained and significant global cooling could kill many [[Polar circle|polar]] and [[temperate]] species and force others to migrate towards the [[equator]]; reduce the area available for [[Tropics|tropical]] species; often make the Earth's climate more arid on average, mainly by locking up more of the planet's water in ice and snow. The [[glaciation]] cycles of the [[current ice age]] are believed to have had only a very mild impact on biodiversity, so the mere existence of a significant cooling is not sufficient on its own to explain a mass extinction.

It has been suggested that global cooling caused or contributed to the [[Ordovician–Silurian extinction events|End-Ordovician]], [[Permian–Triassic extinction event|Permian–Triassic]], [[Late Devonian extinction|Late Devonian]] extinctions, and possibly others. Sustained global cooling is distinguished from the temporary climatic effects of flood basalt events or impacts.