Monday, January 28, 2008

In Hot Water: Ice Age Defrosted by Warming Ocean, Not Rise in CO2

Warmer waters in the deep Pacific triggered the end of the last ice age, preceding the rise in greenhouse gas levels

Earth's climate can be sensitive, changing after a variety of events. A volcanic eruption or meteorite impact, for instance, can send enough particles into the air to block the sun and cool the climate. A thickening blanket of greenhouse gases can trap heat. And, more commonly, according to some scientists, slight changes in Earth's orientation toward the sun can cause it to cool or warm in so-called Milankovitch cycles (named after the Serbian engineer who first described them). Now, new evidence from a marine sediment core from the deep Pacific points to warmer ocean waters around Antarctica (in sync with the Milankovitch cycle)—not greenhouse gases—as the culprit behind the thawing of the last ice age. More >>>