Arctic Ice Exceeds at Minimum

It is the most typical day this decade for the annual Arctic ice extent minimum. Some take any year’s slightly lower minimum as proof that Arctic ice is dying, but the image below shows extents from 2007, mostly smaller than 2017.

While the daily average extent for the last 10 years bottomed out on day 260, years like 2016 and 2009 hit minimum on day 254. This year’s extent was at 4.7M km2 for a week, hit bottom at 4.6M on day 253, then rose up and over 4.8M km2. SII (Sea Ice Index) 2017 is similar to MASIE, though a bit lower lately. The graph below shows September comparisons at day 260.
Note that as of day 256, 2017 has gone 300k km2 above average, 500k km2 more than 2016, 700k km2 higher than 2007, and 1400k km2 greater than 2012. All regions have added ice, with Central Arctic the only exception. That is likely due to Central Arctic sea already full of ice at 3.1M km2.

The table shows ice extents in the regions for 2017, 10 year averages and 2007 for day 260.

Region	2017260	Day 260 Average	2017-Ave.	2007260	2017-2007
(0) Northern_Hemisphere	4757445	4449204	308241	4045776	711669
(1) Beaufort_Sea	411648	468835	-57187	481384	-69736
(2) Chukchi_Sea	106342	145834	-39492	22527	83815
(3) East_Siberian_Sea	320193	257482	62711	311	319882
(4) Laptev_Sea	241780	123163	118617	235869	5912
(5) Kara_Sea	21251	20846	405	44067	-22816
(6) Barents_Sea	1664	24778	-23114	7420	-5756
(7) Greenland_Sea	90072	213695	-123622	333181	-243109
(8) Baffin_Bay_Gulf_of_St._Lawrence	65653	26566	39086	26703	38950
(9) Canadian_Archipelago	430824	247034	183790	225526	205299
(10) Hudson_Bay	1932	6975	-5042	2270	-338
(11) Central_Arctic	3071252	2912912	158339	2665244	406008

The largest deficits to average are in BCE and Greenland Sea, more than offset by huge surpluses in Central Arctice, CAA and Laptev.

Over this decade, the Arctic ice minimum has not declined, but looks like fluctuations around a plateau since 2007. By mid-September, all the peripheral seas have turned to water, and the residual ice shows up in a few places. The table below indicates where ice is found in September. (Shows day 260 amounts with 10 year averages)

Arctic Regions	2007	2010	2012	2014	2015	2016	2017	Average
Central Arctic Sea	2.67	3.16	2.64	2.98	2.93	2.92	3.07	2.91
BCE	0.50	1.08	0.31	1.38	0.89	0.52	0.84	0.87
LKB	0.29	0.24	0.02	0.19	0.05	0.28	0.26	0.17
Greenland & CAA	0.56	0.41	0.41	0.55	0.46	0.45	0.52	0.46
B&H Bays	0.03	0.03	0.02	0.02	0.10	0.03	0.07	0.03
NH Total	4.05	4.91	3.40	5.13	4.44	4.20	4.76	4.45

BCE (Beaufort, Chukchi and East Siberian) on the Asian side are quite variable as the largest source of ice other than the Central Arctic itself. Greenland Sea and CAA (Canadian Arctic Archipelago) together hold almost 0.5M km2 of ice at minimum, fairly consistently. LKB are the European seas of Laptev, Kara and Barents, a smaller source of ice, but a difference maker some years, as Laptev was in 2016 and 2017. Baffin and Hudson Bays are almost inconsequential. The biggest contributors to 2017 success are Central Arctic, Canadian Archipelago and Laptev.

For context, note that the average maximum has been 15M, so on average the extent shrinks to 30% of the March high before growing back the following winter.

Footnote

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, 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 continues the long and honorable tradition of naval ice charting using modern technologies. More on this at my post Support MASIE Arctic Ice Dataset