February 18th, 2016
By Brian Kahn
The winter of discontent in the northern latitudes continues.
Persistent warmth has baked the region, making snow a no show in parts of Alaska and, perhaps more importantly, slowing the growth of Arctic sea ice. Though it’s still likely a month before the Arctic sea ice reaches its maximum, the current trajectory is not a good one.
Slow and at times non-existent growth has already led to a record low January extent and preliminary data from February indicate sea ice continues to set daily record lows. It was just last year that Arctic sea ice set its record low winter extent, a record that could be short-lived.
January Arctic sea ice extent. The orange line shows the 1981-2010 average. Credit: NASA Earth Observatory
As one of the key indicators of planetary health, the continued disappearance of sea ice raises major concerns about how the planet is faring as the climate warms.
The decline continues a long-term trend. Winter Arctic sea ice extent has been decreasing by 3.2 percent per decade since 1979 when accurate satellite measurements began. The region is warming at twice the rate as the rest of the globe, a trend that’s largely responsible for disappearing ice.
This year is no different with weirdly warm weather slowing sea ice’s annual growth across the region. Ice is missing in large areas across the Barents, Kara and East Greenland seas in the Atlantic region and the Bering Sea and Sea of Okhotsk in the Pacific side of the Arctic, according to NASA Earth Observatory. All told, sea ice extent was 402,000 square miles below average in January. That’s enough missing ice to cover an area four times the size of Colorado.
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The terms “heat wave” and “Arctic winter” are not usually synonymous, yet that’s what the main story has been in the region this winter (OK, heat wave might be a bit much so let’s call it a mild wave). Temperatures were as much as 23°F above normal in January, a key driver in the planet having its most abnormally warm month ever. That includes a period of time early in the month when temperatures cleared freezing around the North Pole, a rarity in a region where clearing 0°F is a stretch during the frigid winter.
Background conditions have also been warming, including the ocean which has driven some of this year’s loss.
“The low winter ice conditions in the Barents have been in part a result of the increase in Atlantic Ocean temperatures in the 1990s,” Julienne Stroeve, a scientist at the National Snow and Ice Data Center, said.
She said that it’s possible ice losses could slow there — or they could even grow — due to the flood of cold water that’s been found there in recent years. The cold water isn’t exactly good news, though, as it’s being driven by increasing melt of Greenland’s ice sheet and is also slowing down the Atlantic Ocean’s main conveyor belt.
One thing that’s not clear is what this year’s low winter ice will mean for summer. After growing all winter, Arctic sea ice starts a decline in the spring before dwindling to a seasonal low, usually around late September.
Preliminary daily data showing 2016 Arctic sea ice extent. The graph also includes 2012, which set a record low minimum, and 2015, which set a record low maximum, as well as the median. Credit: NSIDC
If winter ice decline is a thing, then summer ice decline has been The Thing.
“Certainly the summer ice conditions are unprecedented with the nine lowest in the last nine years,” Stroeve said.
That includes the record set in 2012 as well as last year, which was the fourth-lowest extent ever recorded for Arctic sea ice.
It’s tempting to look at this winter’s anemic ice extent and think this summer could also be record low, but Stroeve cautioned against comparing the two. That’s because while climate change is driving the long-term downward trend in sea ice, weather events also play a major role in the ebb and flow of sea ice in a given year. Still, if the past decade (and longer) is any indication, this summer isn’t likely to set any records for highs.
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