As reported by NASA, Arctic sea ice reached its annual minimum extent on Sept. 19 and then again on September 23, 2018. Data recorded by the satellites show that 1.77 million square miles have effectively tied with 2008 and 2010 for the sixth lowest summertime minimum extent.
The cap of frozen seawater, Arctic sea ice that blankets most of the Arctic Ocean and neighboring seas in wintertime, changes its pattern following the seasons. It becomes denser during the fall and shrinks during the spring and summer. But as per reports of the past few decades, it is prominent that summertime decrease was particularly much rapid in the Arctic sea ice extents. This has made scientists worry as the shrinking can ultimately affect the planet’s weather patterns and the circulation of the oceans.
It is found that since the late 1970s, the Arctic sea ice extent has shrunk on average about 21,000 square miles and is estimated to shrink more with each passing year. The already shrunken ice for the past four decades is estimated to be equivalent of losing a chunk of sea ice the size of Maryland and New Jersey combined.
But to the good news as Claire Parkinson, a climate change senior scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, exclaimed: “This year’s minimum is relatively high compared to the record low extent we saw in 2012, but it is still low compared to what it used to be in the 1970s, 1980s and even the 1990s.”
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This year, the Arctic sea had a mixed bag of weather conditions, with some areas experiencing warmer than average temperatures and a rapid melt and other regions remaining cooler than normal. This somehow led to the loss of minimum ice sea extent, i.e., 629,000 square miles, which is apparently below the 1981-2010 average of yearly minimum extents.
NASA reports that one of the most unusual features of this year’s melt season has been the reopening of a polynya-like hole in the icepack north of Greenland, where the oldest and thickest sea ice of the Arctic typically resides. “This summer, the combination of thin ice and southerly warm winds helped break up and melt the sea ice in the region, reopening the hole,” said Melinda Webster, a sea ice researcher with Goddard.
NASA says that measuring the mass and volume changes of the sea ice cover is an important factor, and with the successful launch of NASA’s Ice, Cloud and land Elevation Satellite-2, or ICESat-2, on Sept. 15, scientists will be able to create detailed maps of sea ice thickness in both the Arctic and the Antarctic Circle.