Just like the Arizona road in the image,  Arctic ice extent has dipped in September and is on the rise again.  The graph below shows how September monthly extent averages compare for the years since 2007. 

Overall it resembles the Arizona roadway.  Two low years are followed by two high years, then two low years and so son.  The last two years are low, comparable to 2007, and may portend higher ice extent ahead. As usual MASIE and SII are showing nearly the same monthly averages, 4.0M km2 for MASIE and 3.9M km2 for SII. The graph below shows how the ice dipped and recovered in 2020 compared to the 13-year average and some notable years.

September 2020 daily minimum was lower than all previous years except for 2012.  As noted previous this year’s anomaly was the hot Siberian summer melting out the Eurasian shelf seas and the bordering parts of the Central Arctic Sea.  In 2012 it was the Great Arctic Cyclone in August of that year.  After day 255, ice recovered strongly ending the month higher than 2007, close to 2019 and about 150k km2 less the the average daily minimum on day 260, 4.4M km2

The table shows monthly extent averages for the regions with ice in September for several years and the 13-year average for each region.

Sept. Monthly Averages	2007	2012	2019	2020	Average	SD %
(0) Northern_Hemisphere	4286957	3622648	4124035	3969085	4630779	10%
(1) Beaufort_Sea	558424	212051	382779	620409	487498	31%
(2) Chukchi_Sea	49690	52539	111412	77598	172143	53%
(3) East_Siberian_Sea	1251	53411	73023	121408	287777	63%
(4) Laptev_Sea	246278	44336	87121	28	141604	81%
(5) Kara_Sea	49502	717	166	13063	24612	102%
(6) Barents_Sea	6782	0	13238	0	18757	183%
(7) Greenland_Sea	334147	263899	173116	235216	197263	33%
(8) Baffin_Bay_Gulf_of_St._Lawrence	33043	15591	16589	20361	32926	50%
(9) Canadian_Archipelago	252140	198502	265335	339996	299817	30%
(10) Hudson_Bay	10998	9502	0	2783	7947	135%
(11) Central_Arctic	2743433	2771014	3000459	2537271	2959458	6%

The last column shows the Standard Deviation % for each region and for NH as a whole.  Over this period the NH fluctuations have been +/- 10%.  The most variable is Barents Sea, which can be zero or over 200k km2.  Hudson Bay and Kara likewise either melt out or retain significant ice. The Central Arctic varies little from year to year.

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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October 1, 2020 at 12:24PM