November’s Arctic ice cover dips to new monthly low
Arctic ocean’s mid-month ice shrinkage “an almost unprecedented occurrence for November”
November brought record-breaking high monthly temperatures in many Nunavut communities and across most of the circumpolar region.
At the same time, November’s average Arctic sea ice extent for November set a record low, reflecting those unusually high air temperatures, winds from the south, and a warm ocean, the Colorado-based National Snow and Ice Data Centre reported Dec. 6.
“For the globe as a whole, sea ice cover was exceptionally low,” the NSIDC said, referring also to the state of ice at the South Pole.
In November 2016, Arctic sea ice extent averaged 9.08 million square kilometres—the lowest November cover noted in the satellite record.
This is 800,000 square kilometres below levels in November 2006, and 1.95 million square kilometres below the 1981 to 2010 long-term average for November, the NSIDC said.
At this time of year, air temperatures near the surface of the Arctic Ocean are generally well below freezing, the NSDIC also said—but this year has seen exceptional warmth.
The overall rate of ice growth this November was 88,000 square kilometres per day, a bit faster than the long-term average of 69,600 square km per day.
But for a few days in the middle November, the Arctic sea ice cover growth went into a slump, decreasing by 50,000 square km—”an almost unprecedented occurrence for November over the period of satellite observations,” the NSIDC said.
November air temperatures were far above average over the Arctic Ocean and Canada, above the 1981 to 2010 average over the entire Arctic Ocean, and, locally up to 10 C above average near the North Pole.
Ice formation in Hudson Bay during November was 40 per cent of its usual extent, according to the Canadian Ice Service.
And Ocean Networks Canada’s Cambridge Bay ocean observatory, which has been monitoring ocean conditions in this western Nunavut community since 2012, has produced sea ice measurements that also show these same trends.
In Cambridge Bay, the ice thickness is less than about half of what it should be.
While sea ice growth started to grow in October as usual, Oceans Network said Dec. 5 that the rate of growth in 2016 has been slow.
Sea ice over the Cambridge Bay underwater observatory is typically more than 50 centimetres (about 19 inches) thick by early December, while this year it is only 23 centimetres (nine inches,) the release said.
On Dec. 4 in Cambridge Bay, the air temperature was minus 8.4 C, compared to minus 22 C in 2015, and the ice thickness was 23 cm (nine inches,) compared with 56 cm (22 inches) in 2015.
Overall, in the Arctic, November sea ice extent for 1979 to 2016 shows a decline of five cent per decade.