Molteni writes: "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."

This July 10, 2008, file photo made with a fisheye lens shows ice floes in Baffin Bay above the Arctic Circle, seen from the Canadian Coast Guard icebreaker Louis S. St.-Laurent. (photo: Jonathan Hayward/AP)

“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.

The effects are being felt far below the 66th parallel. States in the Upper Midwest experienced their warmest falls ever, with temperatures running about 15 degrees warmer than average through the second week of November. Minnesota experienced the longest growing season ever recorded: 220 days. And the Twin Cities set a record for the latest frost in history.

On his weather nerd cult blog the Updraft, Minnesota Public Radio chief meteorologist Paul Huttner said that the Arctic “was broken.” Normally, northwest winds blow down from the Arctic over snow-covered ground and iced-over lakes before reaching the US. But this year bare ground all the way up the Arctic circle allowed the sun to warm the upstream air mass more efficiently (no snow means no albedo effect). “The Arctic is North America’s refrigerator,” Huttner says. “If it stops getting as cold as it should, the effects are felt far and wide. I always say that the Arctic is no Las Vegas. Whatever happens in the Arctic, doesn’t stay in the Arctic.”

Which is why climate scientists are gathering data points to try to understand what this anomaly means for the future. It’s too soon to tell if the extreme temperatures are part of a pattern or just an outlier, Serreze says. But if there’s one thing history teaches us, it’s that the Arctic is not as resilient as it once was. Thick layers of old sea ice are the Arctic’s buffer against rare weather events—and that kind of ice has been rapidly disappearing. In the 1980s, multiyear ice made up 20 percent of sea ice cover; today, it’s only 3 percent. As those numbers decline, the Arctic becomes more vulnerable to wide temperature fluctuations.

“Had that same pattern set up in 1980, the sea ice could have taken the punch,” say Serreze. “Now it can’t. And what we’ve learned is that the response of the ice to these extreme events is changing, and with it so are the odds. It loads the dice.”

Dear Arctic, may the odds be ever in your favor.