Polar Heat Bringing Harder Winters

• by Stephen Leahy (oslo)
• Tuesday, June 15, 2010
• Inter Press Service

Climate change has warmed the entire Arctic region, melting 2.5 million square kilometres of sea ice, and that, paradoxically, is producing colder and snowier winters for Europe, Asia and parts of North America.

'The exceptional cold and snowy winter of 2009-2010 in Europe, eastern Asia and eastern North America is connected to unique physical processes in the Arctic,' said James Overland of the NOAA/Pacific Marine Environmental Laboratory in the United States.

'In future, cold and snowy winters will be the rule rather than the exception' in these regions, Overland told IPS.

Scientists have been surprised by the rapid warming of the Arctic, where annual temperatures have increased two to three times faster than the global average. In one part of the Arctic, over the Barents and Karas Seas north of Scandinavia, average annual temperatures are now 10 degrees C higher than they were in 1990.

Overland explains the warming of the Arctic as the result of a combination of climate change, natural variability, loss of sea ice reflectivity, ocean heat storage and changing wind patterns, which has disrupted the stability of the Arctic climate system. In just 30 years, all that extra heat has shrunk the Arctic's thick blanket of ice by 2.5 million square kilometres - an area equivalent to more than one quarter the size of the continental U.S.

The changes in the Arctic are now irreversible, he said.

'This is a very big change for the entire planet,' said David Barber, an Arctic climatologist at the University of Manitoba in Canada. The planet's cold polar regions are crucial drivers of Earth's weather and climate.

'It has been one million years, some think 14 million years, since the Arctic was ice-free,' Barber told the more than 2,300 researchers in Oslo at the largest-ever gathering of the polar-science community.

The International Polar Year (IPY), which just ended with the Oslo Science conference last weekend, involved more than 50,000 scientists from 60 countries conducting 30 months of unprecedented research at both poles. The last IPY was 50 years ago and led to the creation of the Antarctic Treaty to protect the southern polar region.

'Much of the remaining ice in the Beaufort Sea is rotten,' said Barber, who spent long periods on research icebreakers in the region. Such vessels can only break through ice a little over a metre thick but they were plowing through multi-year ice 14 metres thick, he said.

'We watched a piece of ice the size of Manhattan break up right before our eyes,' Barber said.

Although the ice recovers in winter and satellites recorded a full recovery this past winter, in reality much of it was a thin layer of ice on top of old rotten ice, he said. That explains the rapid decline already this year, a near-record low for May. At the end of the Arctic summer, the decline will likely come close to setting another new record, many here said.

Barber says an ice-free summer may be just three or four years away, when icebreakers will no longer be needed to navigate the region.

'The ice pack looks like Swiss cheese,' agreed Mark Serreze, a senior research scientist at the National Snow and Ice Data Centre in Boulder, Colorado.

'It is inescapable this will be another very low year (in terms of ice extent),' Serreze told IPS.

With ever more open water absorbing the sun's heat, the Arctic Ocean is warming up, melting more ice in a positive feedback loop. A day of 24-hour summer sun in the Arctic puts more heat on the surface than a day in the tropics, said Overland. That extra heat in the ocean is gradually released into the lower atmosphere from October to January as the region re-freezes during the 24-hour nights.

Temperatures in January were -2C over the water, while the land was -25C, making conditions far windier and producing more snowfall than normal. Heavy snow on the remaining ice insulates it from the cold air, preventing it from thickening during the long winter.

'Sea ice is the key system in Arctic. It is just like a tropical forest...if the forest is cut down it affects the entire food web,' Barber said.

Not only does the loss of ice affect conditions locally but 'what happens in the Arctic dictates some of what happens in the mid-latitudes,' he added.

This huge mass of warmer air over the Arctic in the late fall not only generates more wind and snow locally, several studies have now documented the impacts on global weather patterns.

The winter of 2005-6 was the coldest in 50 years in Japan and eastern Eurasia, reported Meiji Honda, a senior scientist with the Climate Diagnosis Group at Japan's Agency for Marine-Earth Science and Technology. Honda's studies show that the air over the Arctic was quite warm in the fall of 2005, which altered normal wind patterns, pushing the jet stream further south and bringing arctic cold to much of Eurasia and Japan. He also documented the same mechanism for the colder winters of 2007-8 and 2009-10, he told participants.

In eastern North America, the same conditions of 2007-8 produced increased precipitation and colder temperatures in the winter. As the sea ice declines, big impacts are likely to be seen in this region, said Sara Strey of the University of Illinois.

Another 'wild card' in terms of effects from the Arctic warming is how much and how fast the region's permafrost - permanently frozen landscape - that contains enormous amounts of carbon and methane will also melt.

'Things have to change in the Arctic but we don't know what they will all be. That's the scary part,' said Serreze.

'Our entire infrastructure is based on the status quo,' he said, namely a stable climate of the past 10,000 years. 'Change is already here. We must start adapting now. '

© Inter Press Service (2010) — All Rights ReservedOriginal source: Inter Press Service

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