Arctic sea ice declined in mid-November
Arctic sea ice extent set a new record low this near, heightening concerns that the pace of the Arctic meltdown is speeding up. Antarctic sea ice extent also declined to a record low for the month, with sea ice cover worldwide dropping to an exceptionally low level, according the scientists at the National Snow and Ice Data Center.
Specifically, the blanket of ice around the North Pole averaged 3.51 million square miles for the month, the lowest November in the satellite record, and 309,000 square miles below the record set in November 2006. Through 2016, the linear rate of decline for November is 21,400 square miles per year, or 5.0 percent per decade.
The record low came even through the average daily growth rate was above average because for a short time in the middle of the month, the sea ice cover actually got smaller, an almost unprecedented occurrence for November during the era of satellite observations.
Warm conditions have generally prevailed since October. In November, air temperatures were far above average over the Arctic Ocean and Canada, with readings about 18 degrees Fahrenheit above average near the North Pole. Cold air was displaced southward toward Eurasia, where temperatures were as much as 7 to 14 degrees Fahrenheit below average, with record snow events were reported in Sweden and across Siberia early in the month.
The sea extent was in part shaped by an unusual weather pattern. Rather than storms sweeping from Iceland, across the Norwegian Sea and into the Barents Sea, T an unusual jet stream pattern carried storms up through the Fram Strait (between Svalbard and Greenland).
Sea surface temperatures in the Barents and Kara Seas remained unusually high, which also helped prevent ice formation. These high sea surface temperatures are a result of warm Atlantic water circulating onto the Arctic continental shelf seas.
That warmth prevented formation of sea ice in the fjords of the Svalbard archipelago, where sea ice usually begins to form in early November. This November, however, no sea ice was observed. Throughout autumn, the wind pattern transported warm and moist air to Svalbard, leading to exceptionally high air temperatures and precipitation, which fell as rain.
Atmospheric and oceanic conditions in the fjord system were assessed by students from the University Centre in Svalbard. They noted an unusually warm ocean surface layer about 7 degrees Fahrenheit above the salinity-adjusted freezing point. Coinciding with exceptionally high air temperatures over Svalbard during autumn, the water has hardly cooled at all, and it is possible that no sea ice will form this winter.Scientists say that shifts in northerly branches of the Gulf Stream have changed since 2006, bringing more Atlantic Ocean water toward the Arctic.
Antarctic sea ice this year reached its annual maximum extent on August 31, much earlier than average. The decline since then has led to a new record low for November — more than twice the record deviation from average set in 1986. Ice extent is lower than average on both sides of the continent, particularly within the Indian Ocean and the western Ross Sea, but also to a lesser extent in the Weddell Sea and west of the Antarctic Peninsula in the eastern Bellingshausen Sea. Several very large polynyas (areas of open water within the pack) have opened in the eastern Weddell and along the Amundsen Sea and Ross Sea coast.