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Once a thick and resilient structure, Arctic sea ice is now thinner and more vulnerable to the seasons than ever before, according to new NASA research. 2020's Arctic sea ice cover shrank to the second-lowest extent since modern record-keeping began in the late 1970s. An analysis of satellite data by NASA and the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder shows that the 2020 minimum extent, which was likely reached on Sept. 15, measured 3.74 million square kilometres (1.44 million square miles).
Combining satellite data and submarine sonars, the study reveals that 70 percent of today's ice cover consists of seasonal ice, the stuff that forms and melts within a single year, instead of thicker, established ice. While younger sea ice does grow faster, more coverage is not always better. Seasonal sea ice, no matter how extensive, cannot trump the durability of old age and volume.
With a flimsier foundation, Arctic sea ice will find itself increasingly beholden to the whims of the wind and weather. It will also melt far more easily come summertime and especially as global warming continues to heat up our seasons and our oceans.