Arctic Ice Surprises

 

Imargery date refers to Google Earth capture of land forms. Ice extents are for Sept. 5, 2016 from MASIE. Click on image to zoom in.

Northabout is entering the North West Passage using the southern route, heading for Cambridge Bay.  As the image shows, the channels are ice-free.  Serenity exited some days ago, did some sight-seeing in Baffin Bay and is nearing her first Greenland port.

MASIE images of Arctic ice extent show a plateau in ice extent for the first 5 days of September, remaining steadily above 4.5M km2.  Day 249 is just 11 days short of the most frequent day of annual minimum.  So this is the crunch time in the annual battle between the ocean water and ice. The decline of ice extent is shown below since August 15 (August being the month of greatest loss of ice).

 

It is too early to say the annual minimum occurred on Aug. 31 but that day is still standing five days into September.  Ice extents this month are virtually the same for last year and this.  SII is showing ~300k km2 less ice than MASIE in Sept. The table below shows ice extents in the regions for day 249:

Region	2016249	2015249	Difference
(0) Northern_Hemisphere	4571635	4596740	-25105
(1) Beaufort_Sea	283062	476314	-193253
(2) Chukchi_Sea	447119	236111	211008
(3) East_Siberian_Sea	171984	327884	-155900
(4) Laptev_Sea	374930	56421	318509
(5) Kara_Sea	2067	7760	-5694
(6) Barents_Sea	217	18	199
(7) Greenland_Sea	182352	179286	3066
(8) Baffin_Bay_Gulf_of_St._Lawrence	17028	58674	-41647
(9) Canadian_Archipelago	265112	247465	17647
(10) Hudson_Bay	239	52934	-52695
(11) Central_Arctic	2826476	2953039	-126563

Surpluses in Chukchi and Laptev more than offset deficits in Beaufort and E. Siberian seas.  Baffin and Hudson Bays are much lower this year, but they have little left to lose compared to 2015.  The most significant issue is Central Arctic being lower than last year, which may yet produce a lower September monthly minimum.  Time will tell.

Summary of Year To Date

Someone asked how the annual average ice extent was coming along this year, so I crunched the numbers.

The graph summarizes the changing extents of Arctic ice as measured by two primary datasets: MASIE (Multi-sensor Analyzed Sea Ice Extent) and SII (Sea Ice Index -solely from satellite passive microwave sensors).

Measured in M km2, the two highest lines are the monthly average extents reported for the first 8 months of 2016. The two horizontal lines show the YTD average from the 8 months. At the bottom are the deviations from 10 yr. Averages for each month (from each dataset).

It is clear that MASIE was reporting slightly more ice early on, and then the two estimates have been close together since. The deviation below average grew up through May, with SII reporting 1M km2 deficit. As of August, both MASIE and SII are showing ice extent down about 0.5M km2.

The 10 yr. Averages of extents for the YTD (8 months) are exactly 12M km2 in both datasets. So Masie YTD is ~3% below average and SII YTD is ~5% down.

Summary

There will be much to do about Arctic ice death spirals in the weeks ahead as 2016 continues to show lower extents. Most likely the September average will be lower than last year, an event lasting perhaps 2-3 weeks before refreezing brings it back over last year’s minimum. Only someone pushing an agenda would claim such a short phenomenon contained within a single month of the year shows the climate is changing.

For more on making sense of Arctic Ice graphs see Ice House of Mirrors

For those who want to see numbers, the table is below.

Monthly	2006-2015	2016	2006-2015	2016	2016	2016-10yr Ave	2016-10yr Ave
Averages	MASIE	MASIE	SII	SII	SII Deficit	MASIE	SII
Jan	13.872	13.922	13.780	13.472	-0.450	0.049	-0.308
Feb	14.785	14.804	14.632	14.210	-0.593	0.019	-0.422
Mar	15.008	14.769	14.886	14.405	-0.364	-0.239	-0.481
Apr	14.308	13.917	14.307	13.694	-0.223	-0.391	-0.613
May	12.767	12.086	12.960	11.900	-0.186	-0.681	-1.060
June	10.952	10.419	11.192	10.353	-0.066	-0.533	-0.839
July	8.401	8.067	8.421	7.920	-0.147	-0.334	-0.501
Aug	6.066	5.531	5.838	5.390	-0.141	-0.535	-0.448
YTD Ave.	12.020	11.689	12.002	11.418	-0.271	-0.331	-0.584

September Minimum Outlook

Historically, where will ice be remaining when Arctic melting stops? Over the last 10 years, on average MASIE shows the annual minimum occurring about day 260. Of course in a given year, the daily minimum varies slightly a few days +/- from that.

For comparison, here are sea ice extents reported from 2007, 2012, 2014 and 2015 for day 260:

Arctic Regions	2007	2012	2014	2015
Central Arctic Sea	2.67	2.64	2.98	2.93
BCE	0.50	0.31	1.38	0.89
Greenland & CAA	0.56	0.41	0.55	0.46
Bits & Pieces	0.32	0.04	0.22	0.15
NH Total	4.05	3.40	5.13	4.44

Notes: Extents are in M km2.  BCE region includes Beaufort, Chukchi and Eastern Siberian seas. Greenland Sea (not the ice sheet). Canadian Arctic Archipelago (CAA).  Locations of the Bits and Pieces vary.

As the table shows, low NH minimums come mainly from ice losses in Central Arctic and BCE.  The great 2012 cyclone hit both in order to set the recent record. The recovery since 2012 shows in 2014, with some dropoff last year, mostly in BCE.

Summary

We are nearing the end of the melt season, and the resulting minimum will depend upon the vagaries of weather between now and September 16 or so.  Early on, 2016 was slightly higher than 2015 in March, lower in May and narrowing the gap late June and late July. Note: 2016 melt season is starting without the Blob, with El Nino over, and a cold blob in the North Atlantic.  The AO has been hovering around neutral, now possibly indicating cloud cover reducing the pace of melting.

Meanwhile we can watch and appreciate the beauty of the changing ice conditions.

Arctic sea ice in summer 2015. This photo was made during an expedition of the German research icebreaker Polarstern into the central Arctic Ocean. Credit: Stefan Hendricks

Footnote:  Regarding the colder than normal water in the North Atlantic

A 2016 article for EOS is entitled Atlantic Sea Ice Could Grow in the Next Decade

Changing ocean circulation in the North Atlantic could lead to winter sea ice coverage remaining steady and even growing in select regions.

The researchers analyzed simulations from the Community Earth System Model, modeling both atmosphere and ocean circulation. They found that decadal-scale trends in Arctic winter sea ice extent are largely explained by changes in ocean circulation rather than by large-scale external factors like anthropogenic warming. (my bold)

From the Abstract of Yeager et al.

We present evidence that the extreme negative trends in Arctic winter sea-ice extent in the late 1990s were a predictable consequence of the preceding decade of persistent positive winter North Atlantic Oscillation (NAO) conditions and associated spin-up of the thermohaline circulation (THC). Initialized forecasts made with the Community Earth System Model decadal prediction system indicate that relatively low rates of North Atlantic Deep Water formation in recent years will result in a continuation of a THC spin-down that began more than a decade ago. Consequently, projected 10-year trends in winter Arctic winter sea-ice extent seem likely to be much more positive than has recently been observed, with the possibility of actual decadal growth in Atlantic sea-ice in the near future. (my bold)