Wintertime sea ice in the Arctic has tied last year’s record low, the National Snow and Ice Data Center said on Thursday.
Sea ice in polar regions acts like a planetary air-conditioner by reflecting away the sun’s heat. It also provides habitat to animals and regulates ocean conditions. Each summer in the Northern Hemisphere, as temperatures rise in the Arctic, sea ice melts and then freezes back in winter. The scale of this refreezing is critically important because it is a leading factor influencing how much ice can remain unmelted during the summer.
Ice is vanishing worldwide as humans burn fossil fuels for energy and emit greenhouse gasses. But it’s disappearing particularly quickly in the Arctic, which is warming four times as fast as the rest of the planet.
Only 5 percent of the oldest, thickest sea ice recorded in the 1980s has survived to the present day. In the same amount of time, summertime sea ice cover has been halved, shrinking by some 12 percent per decade.
Right now is when sea ice should be near a yearly peak, said Walt Meier, a senior research scientist at the National Snow and Ice Data Center at the University of Colorado Boulder. Last year, the smallest amount of new winter sea ice formed since record keeping began in 1979, and this year tied that low.
Not every year brings a record, he said. But this year is relatively extreme, he said. Based on overall trends, there’s the possibility that, by 2040, an area the size of the continental United States could go from being completely covered in sea ice to ice-free each summer, Dr. Meier added.
However, he said, exactly when and where ice might vanish is somewhat uncertain because of the variability in year-to-year weather patterns.
This year, scientists are bracing for a hot summer. Signs indicate that an El Niño, a pattern of warm water in the Pacific Ocean that occurs a few times each decade and that tends to heat up parts of the globe and amplify ice loss, is forming.
Sea ice is politically significant, too. As it dwindles, previously impassable parts of the Arctic Ocean have become open to shipping, presenting economic opportunities. For northern countries, including the United States, which has Arctic territory in Alaska, increasingly accessible oceans are also an emerging national security concern.
The Trump administration has made large cuts to climate research. Last October, the National Snow and Ice Data Center announced it would suspend and reduce several of its sea ice analysis services and tools, like monthly reports, because funding had not been renewed.
At the other end of the planet, where summer is drawing to close, Antarctic sea this year fared notably better than previous ones and ranked at the 16th-lowest yearly minimum in the 48 years since satellite records began.
Sachi Kitajima Mulkey covers climate and the environment for The Times.
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