Posted by: arnegrim | May 4, 2011

ancient Global warming

“…Likewise, ancient giant ant fossils have been found in Europe in areas that were tropical during the early part of the Eocene, an epoch that lasted from 56 million to 34 million years ago, a time when the continents were closer together and the sea level was low: “You could have walked from Vancouver to London across dry land,” Archibald said.

But to cross the continents, you still had to traverse the Arctic. Back then, the Arctic was much warmer than it is today, a temperate zone rather than a winter wonderland.

An open Arctic for ants

“Temperate” would have been too chilly for the giant ants, however. The key to the ants’ march, Archibald and his colleagues found, were relatively brief periods in which temperature shot up enough to make the Arctic passable. These periods, which lasted between 170,000 and 55 million years ago, may have been driven by the release of carbon dioxide from sediment.

The warm periods would have brought the average temperature in the coldest Arctic months up to 46 degrees Fahrenheit (8 degrees Celsius), a survivable temperature for the tropical ants…”



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