Global warming could mean colder winters

Wednesday 24th Nov 2010 by theWeather Club

Overall warming of Earth's northern hemishere could result in more cold winters. New research has found that diminishing sea-ice in the eastern Arctic causes regional heating of the lower levels of the atmosphere. This heating appears to cause strong anomalies in atmospheric currents, which could trigger an overall cooling of the northern continents, according to the study recently published in the Journal of Geophysical Research.

"These anomalies could triple the probability of cold winter extremes in Europe and northern Asia," says physicist Vladimir Petoukhov, lead author of the study and climate scientist at the Potsdam Institute for Climate Impact Research. "Recent severe winters like last year's or the one of 2005-06 do not conflict with the global warming picture, but rather supplement it." The researchers base their assumptions on an elaborate computer model of general air circulation. They also focussed on the Barents-Kara Sea north of Norway and Russia where a drastic reduction of ice was observed in the winter of 2005-06.

Areas of the sea lacking the ice cover lose more warmth to the windy arctic atmosphere than ice covered areas. What the researchers did was to feed the model with data, gradually reducing the sea ice cover in the eastern Arctic from 100 percent down to 1 percent in order to analyse the relative sensitivity of winter atmospheric circulation. The results show a much more complicated picture than first thought. With sea ice changes virtually guaranteed, it is a complication we will have to get to grips with.

"Our simulations reveal a rather pronounced nonlinear response of air temperatures and winds to the changes of sea-ice cover," Petoukhov says. "It ranges from warming to cooling to warming again, as sea ice decreases." And the study suggests that abrupt changes in atmospheric circulation currents in the sub-polar and polar regions could be very likely. Warming of the air over the Barents-Kara Sea seems to bring cold winter winds to Europe. "This is not what one would expect," Petoukhov says. "Whoever thinks that the shrinking of some far away sea-ice won't bother him could be wrong."

So it if you have already bought you swimwear, looking forward to the lazy afternoons on the newly tropical beaches of Southern England. It could be time to start looking for that receipt.

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