In the first two weeks of December we can see Chukchi at the left filling in with only 8% open water remaining, and Bering starting to freeze. On the right, Hudson bay is almost fully iced, while Baffin is freezing toward Greenland. Maximum ice is showing in CAA (Canadian Archipelago), Beaufort, East Siberian, Central Arctic, Laptev and Kara.
Arctic Ice Extents have reached 12M km2, up from 4.6M km2 at Sept. minimum. This means 50% of the annual maximum has been gained, with 20% of ice cover to be added in the three months before mid March.
The graph compares extents over the first 14 days of December.
2017 has reached 12M km2, close to the 10 year average, while 2012 has recovered with a surplus. 2016 is about 260k km2 behind and 2007 lags by 520k km2. At this point MASIE and SII are both tracking the 10-year average, with SII about 200k km2 lower.
The Table below shows where ice is located on day 348 in regions of the Arctic ocean. 10 year average comes from 2007 through 2016 inclusive.
The deficits to average are primarily in Barents and Bering Seas. Surpluses are large in Hudson Bay, Okhotsk and Kara Seas. Compared to 2007, most seas are in surplus, with only Hudson Bay slightly late.
Some people unhappy with the higher amounts of ice extent shown by MASIE continue to claim that Sea Ice Index is the only dataset that can be used. This is false in fact and in logic. Why should anyone accept that the highest quality picture of ice day to day has no shelf life, that one year’s charts can not be compared with another year? Researchers do this analysis, including Walt Meier in charge of Sea Ice Index. That said, I understand his interest in directing people to use his product rather than one he does not control. As I have said before:
MASIE is rigorous, reliable, serves as calibration for satellite products, and uses modern technologies to continue the long and honorable tradition of naval ice charting. More on this at my post Support MASIE Arctic Ice Dataset