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quinta-feira, 26 de maio de 2011

@BreakingScience significant role of #oceans in global cooling

New research points to the significant role of oceans in ancient global cooling via

http://www.physorg.com/

Thirty-eight million years ago, tropical jungles thrived in what are now the cornfields of the American Midwest and furry marsupials wandered temperate forests in what is now the frozen Antarctic. The temperature differences of that era, known as the late Eocene, between the equator and Antarctica were only half of what they are today. A debate has long been raging in the scientific community on what changes in our global climate system led to such a major shift from the more tropical, greenhouse climate of the Eocene to the modern and much cooler climates of today.

New research published in the journal Science, led by Rensselaer Polytechnic Institute scientist Miriam Katz, is providing some of the strongest evidence to date that the Antarctic Circumpolar Current (ACC) played a key role in the major shift in the global climate that began approximately 38 million years ago. The research provides the first evidence that early ACC formation played a vital role in the formation of the modern ocean structure.

"What we have found is that the evolution of the Antarctic Circumpolar Current influenced global ocean circulation much earlier than previous studies have shown," said Katz, who is assistant professor of earth and environmental science at Rensselaer. "This finding is particularly significant because it places the impact of initial shallow ACC circulation in the same interval when the climate began its long-term shift to cooler temperatures."

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