The image above shows recovery of Arctic sea ice extent over the first half of December 2021. As supported by the table later, the pace of refreezing for 2021 exceeded the 14-year average since mid-Nov. and ended close to average, and well above 2020.

The month began with the Arctic core as well as seas on the Eurasian and Can-Am sides (top and bottom) already ice-covered, so no additional extent came from there.  OTOH Hudson Bay (lower right) more than doubled extent, starting with only western shore ice and grew from 320k km2 to 780k km2, 62% of last March maximum.  On the Pacific side, Bering (bottom left) went down to 255k km2 before refreezing up to 426k m2, nearly half of its last max.  Okhotsk (far left) had very little ice to start but now has fast ice growing from the northern shore.

The graph below shows the ice extent growing mid-Nov. to mid-Dec compared to some other years and the 14 year average (2007 to 2020 inclusive).

Note that the  NH ice extent 14 year average increases 2.4M km2 during this period, up to 12.2M km2. MASIE 2021 tracked above average most of the period, returning to the mean at the end. Other years were also nearly average, except for 2020. SII was slightly lower than MASIE most of the time but ended nearly the same.

The table shows where the ice is distributed compared to average. Hudson Bay shows a large deficit, along with smaller ones in Greenland Sea and Baffin Bay.  Offsetting are surpluses in Bering, Barents and Kara Seas.

Illustration by Eleanor Lutz shows Earth’s seasonal climate changes. If played in full screen, the four corners present views from top, bottom and sides. It is a visual representation of scientific datasets measuring Arctic ice extents.