December 22, 2010

Global Warming Adding To Freezing Winters In Europe

A new study has found that global warming is playing a major role in driving the string of freezing European winters over the past decade.

According to the study, the culprit is the Arctic's receding surface ice, which scientists believe could disappear entirely by the century's end.

The study reports that the mechanism uncovered triples the chances that future winters in Europe and north Asia will be similarly inclement.

Cold weather has wreaked havoc throughout Europe during the winter months of 2005 through 2008, dumping snow in southern Spain and plunging eastern Europe and Russia into an unusually deep freeze.

Another cold streak in 2009 through 2010 gave Britain its coldest winter in 14 years.

Climate skeptics who question the effects of global warming, or that humans are to blame, say that the deep chills just give more fire to their doubts.

However, the new study says that global warming has actually contributed to Europe's colder winters.

Rising temperatures in the Arctic have peeled back the region's floating ice cover by 20 percent over the last three decades.

This allows more of the Sun's radiative force to be absorbed by dark-blue sea rather than bounced back into space by reflective ice and snow, accelerating the warming process.

It also has created a massive source of heat during the winter months.

"Say the ocean is at zero degrees Celsius (32 degrees Fahrenheit). That is a lot warmer than the overlying air in the polar area in winter, so you get a major heat flow heating up the atmosphere from below which you don't have when it is covered by ice. That's a massive change," Stefan Rahmstorf, a climate scientist at the Potsdam Institute for Climate Impact Research in Germany told AFP in an interview.

According to a modeling study published earlier this month in the Journal of Geophysical Research, the result is a strong high-pressure system over the newly-exposed sea, which brings cold polar air.

"Recent severe winters like last year's or the one of 2005-2006 do not conflict with the global warming picture, but rather supplement it," Vladimir Petoukhov, lead author of the study and a physicist at the Potsdam Institute said in a statement.

"These anomalies could triple the probability of cold winter extremes in Europe and north Asia," he said.

Researchers created a computer model simulating the impact on weather patterns of a gradual reaction of winter ice cover in the Barents-Kara Sea, which is north of Scandinavia.

Petoukhov said that other possible explanations for uncommonly cold winters "tend to exaggerate their effect."

He also points out that during the freezing 2005 and 2006 winter, there were no unusual variations in the north Atlantic oscillation.

Researchers say that colder European winters do not indicate a slowing of global warming trends, only an uneven distribution.

"As I look out my window is see about 30 centimeters of snow and the thermostat reads -14.0 C," said Rahmstorf, speaking by phone from Potsdam.

"At the same time, in Greenland we have above zero temperatures -- in December."


Image Caption: Ede, Netherlands on December 20, 2009. Credit: Wikipedia   


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