February 27, 2009

CO2 linked to prehistoric global cooling

U.S. researchers say a reduction in greenhouse gases likely caused the relatively swift formation of ice in Antarctica millions of years ago.

Matthew Huber, assistant professor of earth and atmospheric sciences at Purdue University, said ice formed on Antarctica 35.5 million years ago over a period of about 100,000 years. That is considered an overnight shift in geological terms, the university said Thursday in a release.

Our studies show that just over 35 million years ago, 'poof,' there was an ice sheet where there had been subtropical temperatures before, Huber said. Until now we haven't had much scientific information about what happened, Huber said.

Computer modeling suggests the cooling was caused by a reduction of greenhouse gases in the atmosphere.

Mark Pagani, professor of geology and geophysics at Yale University, said air and ocean surface temperatures dropped as much as 18 degrees Fahrenheit during the cooling period.

Previous reconstructions gave no evidence of high-latitude cooling, Pagani said in the release. Our data demonstrate a clear temperature drop in both hemispheres during this time.

The findings are published in the journal Science.