Ice coverage in Arctic at lowest levels since 1978
Ice coverage in the Arctic region is at its lowest level since 1978, with Arctic sea ice nearly 350,000 square miles below its coverage in 2012. Determining the cause is difficult, but the warmer environment could be due to abnormal pressure systems causing greenhouse effects. High pressure systems from Scandinavia drew in warmth through an unusually low pressure system near Russia, making it difficult for ice to form. Climate scientists are using data to determine if the anomaly is due to be prolonged or a one-time occurrence, but the Arctic is not as able to recover as it used to be. In the 1980s, multiyear ice represented 20% of sea ice cover, but today it only represents 3%.
November started out pretty normal for the Arctic. The sun had set for the season, temperatures were dropping, ice was growing rapidly. Winter was coming, right on schedule. And then, a few days ago, everything came screeching to a halt. Ice stopped forming. And then it actually started to melt, thanks to a sudden heat wave that blistered the region with temperatures 20 to 30 degrees Fahrenheit above average. For now, the mass of warm air doesn’t appear to be going anywhere.

That’s bad news for sea ice. Coverage in the Arctic was already at its lowest levels since researchers began using satellite data to measure it back in 1978. And as of November 19, Arctic sea ice was nearly 350,000 square miles below its extent in 2012, the last record-low year. The extreme weather has scientists scrambling to figure out what’s causing the historical temperatures, and more importantly, what their long-term impacts could be.

Climate Change Institute/University of Maine

“It’s absurdly warm over the Arctic Ocean right now and the question is, where the heck is all that heat in the ocean coming from?,” says Mark Serreze, director of the National Snow and Ice Data Center in Boulder, CO. “No one has a real handle on that yet.”

There are a few likely explanations. At this time of year, without the sun’s rays, the ocean begins to lose its heat in the form of infrared radiation. On its way to outer space, the radiation has to pass through the atmosphere, and water vapor and carbon dioxide and other greenhouse gases trap and absorb some of that radiation, heating up in the process.

That’s all pretty normal. But this year, atmospheric circulation patterns are bringing more warmth to the Arctic than usual. Last month, an unusually high pressure system centered over Scandinavia brought in a flow of warm southerly air between Greenland and Norway. At the same time, in the Pacific, an abnormally low pressure system formed just east of Russia, along the Kamchatka Peninsula. That drew in warm heat from the mainland up toward Alaska and the Bering Sea. With their powers combined, they blasted the Arctic with a heavy, sweaty dose of hot air.

This wouldn’t be such a big deal on its own, but warmer and more humid air increases the greenhouse effect. It becomes more and more difficult for the ocean to transmit heat away from its surface, and more and more difficult for ice to form. Which is one explanation for why Arctic sea ice cover continues to run at record low levels this late into the year.