Feb. 2021 Arctic Ice Stays the Course

In January, most of the Arctic ocean basins are frozen over, and so the growth of ice extent slows down.  According to SII (Sea Ice Index) January on average adds 1.3M km2, and this month it was 1.4M.  (background is at Arctic Ice Year-End 2020).  The few basins that can grow ice this time of year tend to fluctuate and alternate waxing and waning, which appears as a see saw pattern in these images.

Two weeks into February Arctic ice extents are growing faster than the 14-year average, such that they are approaching the mean.  The graph below shows the ice recovery since mid-January for 2021, the 14-year average and several recent years.

The graph shows mid January a small deficit to average, then slow 2021 growth for some days before picking up the pace in the latter weeks.  Presently extents are slightly (1%) below average, close to 2019 and 2020 and higher than 2018.

February Ice Growth Despite See Saws in Atlantic and Pacific

As noted above, this time of year the Arctic adds ice on the fringes since the central basins are already frozen over.  The animation above shows Barents Sea on the right (Atlantic side) grew in the last two weeks by 175k km2 and is now 9% greater than the maximum last March.  Meanwhile on the left (Pacific side)  Bering below and Okhotsk above wax and wane over this period. Okhotsk is seen growing 210k km2 the first week, and giving half of it back the second week.  Bering waffles up and down ending sightly higher in the end.

 

The table below presents ice extents in the Arctic regions for day 44 (Feb. 13) compared to the 14 year average and 2018.

Region 2021044 Day 044 Average 2021-Ave. 2018044 2021-2018
 (0) Northern_Hemisphere 14546503 14678564 -132061 14140166 406337
 (1) Beaufort_Sea 1070689 1070254 435 1070445 244
 (2) Chukchi_Sea 966006 965691 315 965971 35
 (3) East_Siberian_Sea 1087120 1087134 -14 1087120 0
 (4) Laptev_Sea 897827 897842 -15 897845 -18
 (5) Kara_Sea 934988 906346 28642 874714 60274
 (6) Barents_Sea 837458 563224 274235 465024 372434
 (7) Greenland_Sea 645918 610436 35482 529094 116824
 (8) Baffin_Bay_Gulf_of_St._Lawrence 1057623 1487547 -429924 1655681 -598058
 (9) Canadian_Archipelago 854597 853146 1451 853109 1489
 (10) Hudson_Bay 1260471 1260741 -270 1260838 -367
 (11) Central_Arctic 3206263 3211892 -5630 3117143 89120
 (12) Bering_Sea 559961 674196 -114235 319927 240034
 (13) Baltic_Sea 116090 94341 21749 76404 39686
 (14) Sea_of_Okhotsk 1027249 930357 96892 911105 116144
 (15) Yellow_Sea 9235 28237 -19002 33313 -24078
 (16) Cook_Inlet 223 11137 -10914 11029 -10806

The table shows that Bering defict to average is offset by surplus in Okhotsk.  Baffin Bay show the largest deficit, mostly offset by surpluses in Barents, Kara and Greenland Sea.

The polar bears have a Valentine Day’s wish for Arctic Ice.

welovearcticicefinal

And Arctic Ice loves them back, returning every year so the bears can roam and hunt for seals.

Footnote:

Seesaw accurately describes Arctic ice in another sense:  The ice we see now is not the same ice we saw previously.  It is better to think of the Arctic as an ice blender than as an ice cap, explained in the post The Great Arctic Ice Exchange.

via Science Matters

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February 14, 2021 at 10:53AM

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