3/12/21 - Arctic Sea Ice Hit Seasonal Peak; 7th-Lowest Maximum On Record, Volume Still Falling
On March 12,* sea ice floating atop the Arctic Ocean reached its greatest extent for the year, covering 14.750 million square kilometers (5.70 million square miles). With the exception of last winter, when sea ice reached just 15.047 million square kilometers (5.8 million square miles), sea ice extent in March 2021 was significantly above recent warm years which have put winter sea ice in jeopardy. This year ranks as the 7th lowest maximum extent since the satellite record began in 1978.
Last year was the hottest on record, and, accordingly, sea ice saw its second lowest extent at the September minimum. This winter might indicate a modest recovery — but there’s a caveat: winter maximums seem to have little correlation to summer minimums. And, moreover, the ice in the Arctic is thin. “Volume keeps going down,” says Mark Serreze, director of the National Snow and Ice Data Center. “We’re still below average [extent] in the Bering Sea and around Svalbard [on the Arctic’s Atlantic Ocean side]. It’s pretty thin ice along the Labrador coast, too.” According to NSIDC data, September Arctic sea ice extent is decreasing at an average rate of 13.1% per decade.
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In other news, both polar regions continue losing ice fast, with the biggest losses, thus far, occurring at sea. In a recent study published in The Cryosphere, University of Leeds researchers found that global ice loss had increased at a record rate, with the Earth losing 28 trillion metric tons of ice between 1994 and 2017. Of concern, the rate of such loss also sped up, from 0.8 trillion metric tons per year in the 1990s to 1.3 trillion metric tons per year in 2017. Scientists examined the ice extent and volume of the Greenland and Antarctic ice sheets, mountain glaciers, Antarctic ice shelves, and Arctic and Antarctic sea ice. The single biggest loss came from Arctic sea ice; the Earth lost 7.6 trillion metric tons in the last three decades.
“Earth’s ice is extremely sensitive to changes in environment and once the delicate balance is upset a number of positive feedback mechanisms kick in that exacerbate the melting,” explains Isobel Lawrence, a research fellow at the Leeds’ Center for Polar Observation and Modelling. Under past circumstances, all that white sea ice would reflect solar radiation back into the atmosphere, maintaining cooler polar temperatures. With the sea ice gone, the dark ocean now absorbs that heat which exacerbates ocean and atmospheric warming.
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https://news.mongabay.com/2021/03/as-arctic-sea-ice-hits-annual-maximum-concern-grows-over-polar-ice-loss-studies/
