Arctic Ice Usual June Swoon

 

The image above shows melting of Arctic sea ice extent over the month of June 2020.  As usual the process of declining ice extent follows a LIFO pattern:  Last In First Out.  That is, the marginal seas are the last to freeze and the first to melt.  Thus at the top center and right of the image, the Pacific basins of Bering and Okohtsk seas lost what little ice they had.  Meanwhile at extreme left, Hudson Bay ice retreats 300k km2 from north to south.  Note center left Baffin Bay loses 320k km2 of ice during the month.  The most dramatic melting is in the Russian shelf seas at the center right.  Laptev and Kara Seas combined to lose 600k km2 of ice extent. The central mass of Arctic ice is intact with some fluctuations back and forth, and as well Greenland Sea and CAA (Canadian Arctic Archipelago) were slow to melt in June

The graph below shows the ice extent retreating during June compared to some other years and the 13 year average (2007 to 2019 inclusive).

 

Note that the  MASIE NH ice extent 13 year average loses about 2M km2 during June, down to 9.6M km2. MASIE 2019 started about 500k km2 lower and lost ice at a similar rate, ending nearly 476 km2 below average.  The most interesting thing being the wide divergence between SII and MASIE reports during June, SII starting the month about 500k km2 higher before narrowing at the end to exceed MASIE by 133.  I inquired whether NIC had experienced any measurement issues, but their response indicated nothing remarkable.  It is notable that MASIE is the low estimate of the two.

The table shows where the ice is distributed compared to average.  Bering and Okhotsk are open water at this point and will be dropped from future monthly updates. The deficit of 476k km2 represents 5% of the total, or an ice extent 5 days ahead of average.

Region 2020183 Day 183 Average 2020-Ave. 2007183 2020-2007
 (0) Northern_Hemisphere 9128615 9604642  -476028  9269301 -140686 
 (1) Beaufort_Sea 982475 882878  99597  891858 90617 
 (2) Chukchi_Sea 730000 703162  26838  637536 92464 
 (3) East_Siberian_Sea 885090 1014587  -129497  855267 29823 
 (4) Laptev_Sea 469839 704231  -234392  646683 -176844 
 (5) Kara_Sea 274007 535421  -261414  596916 -322909 
 (6) Barents_Sea 111016 106522  4494  97267 13749 
 (7) Greenland_Sea 474331 498794  -24463  548566 -74236 
 (8) Baffin_Bay_Gulf_of_St._Lawrence 438007 479675  -41668  414283 23724 
 (9) Canadian_Archipelago 780765 774360  6405  759177 21589 
 (10) Hudson_Bay 739422 686381  53041  613940 125482 
 (11) Central_Arctic 3235174 3202495  32679  3202330 32844 
 (12) Bering_Sea 315 3673  -3357  981 -665 
 (13) Baltic_Sea 0 -4  0
 (14) Sea_of_Okhotsk 7051 11237  -4185  2983 4068 

Note that all of the deficit to average is accounted for by the Russian shelf seas of East Siberian, Laptev and Kara. Beaufort and Hudson Bay are slightly surplus.

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.

via Science Matters

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July 2, 2020 at 01:38PM

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