Environmental scientists gathering data at the North Pole say the climate was so warm 55 million years ago as a result of greenhouse gases, it was possible to swim in the Arctic Ocean. The researchers say the findings provide a window into the future.
An international team of scientists made the discovery about the earth's climate 55 million years ago from sea core samples they gathered during an expedition to the North Pole in 2004.
Researchers say the average temperature at the North Pole back then was 24 degrees Celsius. "It was extremely nice for a swim," said Appy Sluijs. "It's warmer than the present North Sea, for example."
Appy Sluijs of the University of Utrecht in the Netherlands is an author of one of several papers on the expedition that appears in the journal Nature.
Fifty five million years ago, experts say, there was a huge release of a greenhouse gas, possibly methane or carbon dioxide, into the atmosphere. The gas may have been in a deposit in the ocean floor, probably until it was disturbed by a massive geological event ,such as an earthquake.
The result, says Sluijs, was global warming. Researchers found supporting evidence embedded in the Arctic core samples in the form of a tiny algae called dinoflagellates.
"We know for this time interval what type of species were living in the tropics and what kind of species were living on the higher latitudes," said the Dutch scientist. "And now it appears this specific tropical dinoflagellates, this algae, migrated all the way up through the North Pole into the Arctic Ocean."
Researchers also found evidence suggesting there was an abrupt cooling off period on earth.
In a separate paper, Kate Moran of the University of Rhode Island describes how her team found a large pebble in an ice core dating back to 45 million years ago.
"And in order to move something like from land to that part of the ocean, you need to transport it with something that can float and move," said Kate Moran. "And the only way we thing it could have gotten there was from ice. And so what we are suggesting we think the ocean basin started to freeze at that time forming sea ice, perhaps icebergs. And that is much, much earlier than anyone ever thought, that the northern hemisphere actually began to cool."
The researchers say their finding is a good indication of what happens if similar concentrations of greenhouse gases are pumped into the atmosphere in the next few hundred years.