
In the last nine days, sea ice in Barents persists, remaining above 700k km2, well above the decadal average and the previously high 2014. The melting is confined mostly to Bering Sea on the Pacific side, and less so in Okhotsk next door.

The April pattern of ice extent decline is shown is graph below:

2018 is tracking close to 2007 and 2017, all more than 400k km2 below the 11 year average (2007 through 2017 inclusive). SII is showing ~200k km2 less ice throughout. The graph below shows 2018 ice extent is close to the decadal average, except for Bering and Okhotsk Sea, the two Pacific basins.

The table below shows regional ice extents on day 113 comparing to decadal averages and 2017.
| Region | 2018113 | Day 113 Average |
2018-Ave. | 2017113 | 2018-2017 |
| (0) Northern_Hemisphere | 13515699 | 14083321 | -567621 | 13651810 | -136111 |
| (1) Beaufort_Sea | 1070445 | 1069106 | 1339 | 1070445 | 0 |
| (2) Chukchi_Sea | 954262 | 965239 | -10977 | 961723 | -7461 |
| (3) East_Siberian_Sea | 1086737 | 1086195 | 542 | 1083967 | 2770 |
| (4) Laptev_Sea | 897845 | 894453 | 3392 | 897326 | 518 |
| (5) Kara_Sea | 934867 | 916778 | 18090 | 932153 | 2715 |
| (6) Barents_Sea | 724756 | 572825 | 151931 | 546422 | 178334 |
| (7) Greenland_Sea | 516420 | 670606 | -154186 | 673722 | -157302 |
| (8) Baffin_Bay_Gulf_of_St._Lawrence | 1239506 | 1338185 | -98679 | 1444616 | -205110 |
| (9) Canadian_Archipelago | 853109 | 850093 | 3015 | 853214 | -106 |
| (10) Hudson_Bay | 1244858 | 1252135 | -7277 | 1258453 | -13595 |
| (11) Central_Arctic | 3208617 | 3242368 | -33751 | 3245713 | -37096 |
| (12) Bering_Sea | 88256 | 689111 | -600856 | 374254 | -285998 |
| (13) Baltic_Sea | 44869 | 32599 | 12270 | 23289 | 21579 |
| (14) Sea_of_Okhotsk | 648464 | 499591 | 148873 | 283164 | 365300 |
Overall, the 2018 deficit to average is 4%, or 570 k km2. The difference is entirely due to open water in Bering Sea, now a deficit of 600k km2 (down by 90%). Barents and Okhotsk are both above average, by ~30% with Greenland Sea down about 20%. It remains to be seen how fast or slow will be the melting of the Arctic core regions, solidly frozen at this point in the year.


via Science Matters
April 24, 2018 at 01:25PM
