As Americans were donning green shirts and tossing back pints of Guinness, the Arctic was limping toward its annual wintertime sea ice maximum. According to data released Friday by the National Snow and Ice Data Center, it was the second-lowest annual maximum on record.
Sea ice in the Arctic very likely peaked on March 17 at 5.6 million square miles (14.5 million square kilometers), just 450,000 square miles above its maximum extent in 2017. That was the poorest wintertime sea ice showing since satellite record-keeping began in 1979. The four lowest peaks on record? 2015, 2016, 2017 and 2018. It’s almost as if we’re experiencing some sort of trend.
This won’t come as a surprise to anyone who’s been paying attention. It was a winter of sad ice conditions across the Arctic, with especially poor sea ice growth in the Bering Sea, including declines throughout this region during parts of February when the ice should still be growing. These left remote Alaskan Native communities vulnerable to freak coastal waves.
The same heat wave that caused incredible February sea ice declines on the Pacific side of the Arctic took its toll at the North Pole, too, where temperatures soared nearly 50 degrees Fahrenheit above normal last month, causing open water to form north of Greenland in the dead of winter.
Per the NSDIC, it’s the third winter in a row that heat waves like this have been observed over the Arctic Ocean.
While the Arctic is no stranger to occasional wintertime heat waves driven by the advection of warm and moist air polewards, many scientists saw this year’s hot-spell as a harbinger of human-caused climate change. And the long-term pattern of declining sea ice in the Arctic is very clearly climate-driven.
Last December, a report by the National Oceanic Atmospheric Administration found that Arctic sea ice is shrinking faster and reaching lower lows than it has anytime in the past 1,500 years as climate change causes the region to warm twice as fast as the global average.
Antarctic sea ice also veered into near record-low territory this year, although the reasons aren’t as clear cut. For the second year in a row, the sea ice rimming our planet’s southernmost continent plunged, reaching a summertime minimum of 842,000 square miles on Feb. 20-21. It was the second lowest minimum on record, just 27,00 square miles above a record low set last March.
Unlike the Arctic, which has seen dramatic sea ice declines in recent decades, Antarctic sea ice has been slowly but steadily increasing, with the exception of the last few years. Last year’s sea ice plunge, deemed “very unusual” by Antarctic ice researchers, was later attributed to a series of remarkably powerful storms driven by natural variability.
Julienne Stroeve, a sea ice researcher at the National Snow and Ice Data Center, told Earther in an email that she “wouldn’t make too much of the low ice conditions” in the Antarctic, noting that sea ice is highly variable year to year.
In the Arctic, however, “we see clear ice losses during all months and all regions except in the Bering where we have had slight positive trends in winter,” Stroeve said, noting that warm ocean waters seem to explain record-low ice in the Bering this winter.
Zack Labe, a sea ice researcher and PhD candidate at the University of California, Irvine, said it’s important to note that Arctic sea ice declines are happening in all months of the year. Still, he told Earther in an email, “it remains difficult to extrapolate information about the upcoming melt season from the sea ice maximum.”
“Summer weather still has the largest role in determining the extent of the annual September sea ice minimum,” Labe said. “For example, while the last few winters have featured record low sea ice, the following summers were slightly cooler and cloudier than average with no new sea ice minimum records. This record is still held by September 2012.”
Whether or not the summer of 2018 bests the summer of 2012, it seems it’s only a matter of time before that Arctic ice record is broken once more, too.