35.5 mln yr old global cooling caused by sharp decline in CO2

February 27th, 2009 - 1:46 pm ICT by ANI  

Washington, Feb 27 (ANI): A new research has found that prehistoric global cooling that started in Antarctica about 35.5 million years ago, was caused by a sharp drop in the carbon dioxide (CO2) levels.

Even after the continent of Antarctica had drifted to near its present location, its climate was subtropical. Then, 35.5 million years ago, ice formed on Antarctica in about 100,000 years, which is an overnight shift in geological terms.

Our studies show that just over thirty-five million years ago, poof, there was an ice sheet where there had been subtropical temperatures before, said Matthew Huber, assistant professor of earth and atmospheric sciences at Purdue University.

Until now, we havent had much scientific information about what happened, he added.

Before the cooling occurred at the end of the Eocene epoch, the Earth was warm and wet, and even the north and south poles experienced subtropical climates. The dinosaurs were long gone from the planet, but there were mammals and many reptiles and amphibians.

Then, as the scientists say, poof, this warm wet world, which had existed for millions of years, dramatically changed.

Temperatures fell dramatically, many species of mammals as well as most reptiles and amphibians became extinct, and Antarctica was covered in ice and sea levels fell.

History records this as the beginning of the Oligocene epoch, but the cause of the cooling has been the subject of scientific discussion and debate for many years.

The research team found before the event ocean surface temperatures near present-day Antarctica averaged 77 degrees Fahrenheit (25 degrees Celsius).

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

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

To find the result, Huber used modern climate modeling tools to look at the prehistoric climate. The models were run on a cluster-type supercomputer on Purdues campus.

According to Huber, We found that the likely culprit was a major drop in greenhouse gases in the atmosphere, especially CO2.

From the temperature data and existing proxy records indicating a sharp drop in CO2 near the Eocene-Oligocene boundary, we are establishing a link between the sea surface temperatures and the glaciation of Antarctica, he said. (ANI)

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