NSIDC: Arctic sea ice extent has reached annual minimum for year

Alan Bailey

for Petroleum News

The National Snow and Ice Data Center has reported that the extent of the Arctic sea ice likely reached its minimum for this year on Sept. 18. At 1.8 million square miles this year’s minimum ties with the minimums of 2017 and 2018 as the 10th lowest on record since satellite records began nearly 44 years ago. All the lowest extents observed by satellite have happened in the last 16 years, NSIDC said.

(See map for this story in the online issue PDF.)

And this year’s minimum occurred four days later than the median date of the minimum recorded from the satellite records.

The long-term trend in the shrinkage of the minimum sea ice extent since 1979 has averaged 12.6% per decade, with an average loss of 30,300 square miles per year, NSIDC said.

Other key factors in the status of the sea ice are the age and thickness of the ice. Recent years have seen a significant loss of thick multi-year ice, relative to thinner young ice. New microwave scanning technology is now enabling scientists to obtain a better evaluation of the ice thickness, in addition to the area of the ice. In a previous report NSIDC said that microwave imagery had shown that a patch of fairly thick ice had separated from the main ice pack in the East Siberian Sea, and that a smaller thick ice patch had been observed in the Beaufort Sea.

NSIDC also said that both the Northern Sea Route around northern Russia and the Northwest Passage around northern Canada were open for shipping.

Between Sept. 1 and Sept. 18 air temperatures over most of the North American side of the Arctic at an altitude of about 2,500 feet were 2 F to 7 F above 1991 to 2020 levels, but up to 13 F above average over the Greenland ice sheet, NSIDC reported. Low atmospheric pressure over eastern Canada coupled with high pressure over southern Greenland led to southerly winds and the high average temperatures over northern Greenland. Those relatively high temperatures related to an early September ice melt over the ice sheet, NSIDC said.