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Posted at 11:00 AM ET, 07/14/2008

Freedman: Arctic Sea Ice Watch 2008 Update

By Andrew Freedman

As the Mid-Atlantic basks in characteristically warm mid-July weather, in the Far North, trends are emerging that are anything but normal. With the summer sun high in the Arctic sky, scientists recently reported that the sea ice that helps define the region remains on track to meet or beat last year's stunning melt which shocked the climate science and policy communities.

A repeat performance of last year's spectacle, which featured an ice-free Northwest Passage, would be front-page news, and could influence weather and ocean patterns throughout the Northern Hemisphere.

Keep reading to learn how this summer's sea ice extent compares to last year. See our full forecast for local weather.

The latest information on sea ice conditions shows that in June, Arctic sea ice extent was close to the level seen last year at that time. Last year's melt season broke records for the smallest coverage ever observed during the nearly thirty-year history of satellite-based observations, and likely even longer than that. As I've previously written, the sea ice began this year in younger, thinner form than normal, and therefore has been more vulnerable to the potent Arctic summer sun.


Arctic sea ice extent in 2008 relative to 2007. Image courtesy National Snow and Ice Data Center.

Scientists at the National Snow and Ice Data Center (NSIDC) in Colorado reported on July 2 that sea ice began to melt "significantly earlier" in the season than it did last year. In some locations, sea ice began melting two weeks earlier into the summer than it did in 2007. An earlier start to the melt season can result in a more severe loss of sea ice, but it doesn't necessarily point to such an outcome. The key wild cards in determining the extent of this year's melt will be cloud conditions and atmospheric circulation throughout the melt season, the NSIDC stated. Last year both these factors combined to shrink the northern ice cap.

The most sobering aspect of the loss of summer sea ice in the Arctic is that it is occurring at a rate that far exceeds even the most pessimistic scientific projections, which held that the Arctic would not be nearly ice-free for a couple of decades at least.

Arctic sea ice has been a frequent topic of this column, with recent posts covering different aspects of it in May and June.

Therefore, you may be asking yourself, "Hey Freedman, why are you focusing so much on the Arctic, when I live in the Washington, D.C. area? Can you be any more esoteric? What does this story have to do with my weather?"

Aha, that's where things get fascinating. There is a local angle to the Arctic story, it's just a little bit hazy to tease out right now, in part because scientists are racing to catch up to an atmosphere that is behaving at warp speed compared to their scenarios.

By altering the heat budget of the atmosphere in the Far North, sea ice loss will influence weather patterns and ocean currents. Through ripple effects in the air and sea, an increasingly sea ice-free Arctic in the summer may affect the weather in the Mid-Atlantic. The increasing flow of freshwater from the Arctic into the North Atlantic is already altering ocean currents, for example.

Precisely how these changes would manifest themselves is a key question for scientists to explore as they grapple with the rapidly unfolding events in the Arctic.

In addition to shifting weather patterns, the decline of summer sea ice could alter the course of global climate change itself, which in turn would have its own effects on the Mid-Atlantic region. One study published in June, for example, showed that rapidly melting sea ice could instigate or hasten the thawing of permafrost in far inland Arctic locations. This would release more greenhouse gases into the atmosphere, especially methane, and speed up warming around the world.

Changes in the weather, or at least in the impacts of weather, are already being seen in the Far North where indigenous people are noting increasingly powerful and damaging storms. Some towns in Alaska have experienced coastal flooding due to the loss of sea ice, which used to provide a buffer from the turbulent Arctic seas.

"When sea ice is present, less moisture moves from the ocean to the atmosphere, which limits the development of strong storms," the NSIDC web site states. "With less sea ice, stronger storms are possible."

In a subsequent column I will explore some of the scientific evidence for the Arctic ice cover's influence on U.S. weather. Also, stay tuned for further updates on Arctic sea ice as the melt season approaches its peak.

By Andrew Freedman  | July 14, 2008; 11:00 AM ET
Categories:  Climate Change, Freedman, Science  
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