The strange winter of 2016-17 has ended with air temperatures over the Arctic Ocean still several degrees above freezing, and sea ice hitting a record low not seen over nearly four decades of satellite tracking.
Now observers are turning their attention to how the extreme winter weather will affect spring and summer conditions.
“I’ve been studying Arctic climate and weather for 35 years,” said Mark Serreze, the director of the U.S. National Snow and Ice Data Center, part of the University of Colorado at Boulder, but “I’ve never seen anything like what we’ve seen this winter, and the past winter.”
Winter’s overall slow freeze-up means thinner ice coming into the spring melt season, Serreze said, a multiyear trend that has decreased the extent of thick sea ice across the Arctic Ocean. “Even without a warming pattern through summer or anything like that, you know you’re going to have less ice at the end of September than you used to, because we’re starting off the season so much thinner.”
As of March 7, when winter sea ice appeared to reach its maximum area for the season, it covered 14.42 million square km (5.57 million square miles) of the Arctic Ocean, according to the center’s data. That beat the previous record-setting low, set in late February of 2015, by 97,000 square km (37,000 square miles), and was 1.22 million square km (471,000 square miles) below the average area of winter sea ice from 1981 to 2010.
Scientists credit a series of big, heat-bearing North Atlantic cyclones with sending winter temperatures above the freezing mark at the North Pole, according to Serreze, and stalling ice growth, notably in parts of the Barents and Kara seas in the eastern Arctic.
“We had a very wavy jet stream pattern,” he said, “which allowed these very, very strong storms to enter deeply into the Arctic Ocean from the Atlantic.”
But it’s still a mystery to what extent the Arctic’s overall warmer and less icy state, which is largely a result of human-propelled climate change, created those conditions. Serreze points to research by Sukyoung Lee, an atmospheric scientist at Pennsylvania State University, suggesting that La Nina-related atmospheric shifts over the tropical western Pacific may factor into the jet stream’s strange wavy pattern over the Arctic.
“The more we start to understand these things, that’s the sort of information that will help us as a scientific community to understand when the Arctic Ocean is going to become free of sea ice in summer,” he added.
Ice largely failed to form around Norway’s Svalbard archipelago, continuing a trend that stretches back to the early 2000s, according to University of Alberta biologist Andrew Derocher. “There’s a bit of ice there now, but it came in January-February,” nearly two months after pregnant polar bears would normally be looking for dens, said Derocher, an expert on Arctic mammals.
“For the Svalbard population that’s challenging, in that that area’s probably what allowed them to recover after Norway stopped hunting polar bears in 1973,” he added. “If there’s no ice, there’s no polar bears. And a lot of Svalbard didn’t have ice.”
Although sea ice and temperatures were less volatile in the Canadian Arctic, the waters of Hudson Bay remained open much later than usual. That kept the bears on land longer into the fall, away from their preferred prey of calorie-rich ring and harp seals. Scientists will be watching to determine whether that lowered the survival rate of cubs born the previous winter, said Derocher. “The big concern we’ve got is, what’s going to happen now? Will they get a late melt?” he said. “If they do, they tend to do better. They’ll come onto shore a little bit fatter, and then they don’t have to wait as long to get back out onto the sea ice.”
Sea ice formed very late in Alaska, with open waters along the northwestern coast and into the Chukchi Sea remaining much later than usual, according to the Alaska Center for Climate Assessment and Policy. The ice-free conditions allowed hunters in Savoonga on St. Lawrence Island to land a bowhead on January 9, which, according to the center’s website, is the latest “in living memory” that it has been possible to put boats in the water, much less hunt a whale.
Both day- and night-time temperature highs were above average compared to historical norms throughout the region, confirmed Austin Ahmasuk, marine advocate for the Alaska Native corporation Kawerak Inc., via email. “Some villages reported that lagoons or lower estuaries where ice fishing normally occurred were not safe to ice fish … until approximately November 2016,” about a month late. “Folks have noted how little ice there was even into December in the Bering Strait between Wales and Diomede compared to years past.”
“Each winter is a new climate event, it seems, and of late we have come to expect a new dramatic change or more warm weather,” Ahmasuk added. “Coastal erosion and permafrost melt are occurring more rapidly and heating degree days are increasing.”
It’s too soon to tell whether the low winter sea ice will affect the region’s walrus population, which Alaska native communities from Barrow to Bristol Bay depend upon “for fundamental aspects of rural life in Alaska; from the meat, blubber, skin and organs in food, to processing skin and tusks for use in boats, drums or jewelry and handicrafts,” stated Vera Metcalf, the head of the Eskimo Walrus Commission, in an email.
Reduced summer sea ice in past years has led to thousands of walruses repeatedly coming ashore, with unclear ramifications for the population’s overall health and mortality rate.
“With ice cover diminishing and changing as it has in the past few years, our hunters face even greater challenges in traveling greater distances to hunt,” Metcalf stated. But they are grappling with those challenges in the context of hundreds of years of coexistence with the Arctic environment, she added. “We understand that marine mammals present themselves as gifts, and they must be earned by hard work and must be treated properly. The outlook is that we will be ready to hunt and do what is necessary to feed our communities.”
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