A wacky winter over the Arctic Ocean has led to a serious shrinking of its ice stock.
Arctic sea ice levels were recorded at their lowest level for any January on record last month according to the Colorado-based scientists tasked with monitoring it.
“It’s not really unexpected, we’re losing the sea ice in all months,” Mark Serreze, director of the National Snow and Ice Data Center at the University of Colorado. “You don’t expect every year to see a new record low, that’s just not going to happen because there is a lot of variability in that system, variability you see around the planet. (However) it really did stick out, I would say, what we saw this past January, because it was kind of a culmination of a whole lot of crazy things happening over the Arctic Ocean.”
Arctic sea ice extent during January averaged 13.53 million square-kilometres, which is 1.04 million sq-km below the 1981 to 2010 average, according to the center’s data. This was 90,000 sq-km below the previous record January low that occurred in 2011 and was driven by unusually low ice coverage in the Barents Sea, Kara Sea, and the East Greenland Sea on the Atlantic side, and below average conditions in the Bering Sea and Sea of Okhotsk.
Ice conditions were near average in Baffin Bay, the Labrador Sea and Hudson Bay. There was also less ice than usual in the Gulf of St. Lawrence, an important habitat for harp seals. Sea ice levels were below average in Antarctica last month as well, contrasting the record high extent recorded in January 2015.
Data show February is well on its way to setting a record of its own, with ice extent trending below 2012, the current record low for that month.
Technically speaking, it was caused by unusually high air temperatures over the Arctic Ocean and a strong negative phase of the Arctic Oscillation (AO), an atmospheric circulation pattern in which the atmospheric pressure over the polar regions varies in opposition with that over middle latitudes, for the first three weeks of the month. That led to low atmospheric pressure over the North Atlantic and to air temperatures as much as five degrees Celsius above normal over the Arctic before the AO returned to normal in the last week of January.
Data from NASA indicated that after 2015, the warmest year for the globe ever, January saw the largest departure from average of any month on record. The heat, though, was disproportionately distributed in the North, pushing temperatures four degrees Celsius above the 1951-1980 average for the region. The director of the National Weather Service in Alaska told the Washington Post last week that state is experiencing its third-warmest winter since 1925.
Much of the focus by climate scientists this winter has been on the strong El Niño. In the Arctic, however, the AO is a bigger player and its influence often spills out into the mid-latitudes during winter by allowing cold air outbreaks, according to the center. How the AO and El Niño may be linked remains an active area of research.
“It was absurdly warm over the Arctic Ocean in January,” Serreze said. “I’d never seen something like that, where it was so warm across all of the Arctic Ocean, and I’ve been doing Arctic research since the 1980s. You’re seeing that warmth in other areas, too, like Fairbanks (Alaska), which is way above normal temperatures this winter, for example. Even in the early part of the winter, really weird things were happening.”
He referred to a massive storm that took place near the end of last year, between Christmas and New Year’s, that pushed temperatures in the polar region close to the freezing point, if not slightly above. The Atlantic magazine dubbed it the “the storm that will unfreeze the North Pole.”
The storm was associated with the AO, which pumped warm, moisture-rich air “way up into the Arctic.”
“There are drifting buoys up there used for research and some of them showed that you got right up to the freezing point, and here we are at the end of December at the North Pole,” he said. That reading would be close to 50 degrees Fahrenheit above normal for that time of year. “Now, has that ever happened before? Maybe it did, I don’t know. Our ability to measure or observe these things is certainly better than it used to be, but it was an eye-opener.”
He said about a week earlier there was another “pretty unprecedented” storm off Svalbard, an archipelago 800 km north of the Norwegian mainland at about 80 degrees north latitude that caused a lot of havoc of its own, including triggering an avalanche that killed one and sent nine others to hospital.
“So the record low sea ice is just a part of this fascinating story of what’s been happening in the Arctic this winter,” Serreze said. “The Arctic alarm bells have been ringing for quite a while now. Some choose to ignore them, but we see this inexorable change in the Arctic environment. It’s nothing like it was 30 years ago up there in many respects.”
He recalled doing graduate research just south of Alert on northeast Ellesmere Island in 1982, studying the St. Patrick Bay ice caps, a pair of caps near Discovery Harbour.
“We looked on the satellite data a while ago and they’ve almost disappeared,” he said. “Air photos of these things were taken in 1959 and compared to that year, maybe 15 per cent of them is left. That’s one of those things that really bring it home for me. Those were my little ice caps; I studied them to death, I knew every nook and cranny and now they’re going to be gone in a decade or two. That’s symptomatic of what we’re seeing up there. You can’t deny what is happening.”