The darkest time of year at the North Pole is the Winter Solstice, this year on December 21. There has been no sunlight or even twilight since early October. The darkness lasts until the beginning of dawn in early March.

The regrowth of Arctic ice extent was slower than usual until recently. After showing resilience in September, ending higher than 2007, ice growth lagged in October, but is now rapidly ramping up toward the averages.  The map above shows the lack of ice is mainly in marginal seas close to the Atlantic and Pacific oceans.

In the last 19 days, 2016 ice extent has grown by 100k km2 per day, compared to the 10-year average 70k km2 per day.  As of day 355, 2016 ice extent is ~3% less than average (2006 to 2015).  The chart also shows the variability of ice extent over the years during this month.  2015 was the highest ice recovery rate in the last decade, while 2006 ended up the lowest.  The chart also shows 2016 Sea Ice Index (SII) from NOAA has been lagging behind by  ~300k km2.

The table below shows this year compared to average and to 2006 for day 355.

Region	2016355	Day 355 Average	2016-Ave.	2006355	2016-2006
(0) Northern_Hemisphere	12239317	12586206	-346889	12148183	91133
(1) Beaufort_Sea	1070445	1070151	294	1069711	734
(2) Chukchi_Sea	855058	964292	-109234	966006	-110948
(3) East_Siberian_Sea	1087137	1087134	3	1087137	0
(4) Laptev_Sea	897845	897841	4	897845	0
(5) Kara_Sea	851317	865798	-14482	909296	-57979
(6) Barents_Sea	169752	380779	-211027	225917	-56165
(7) Greenland_Sea	487544	584147	-96603	564913	-77369
(8) Baffin_Bay_Gulf_of_St._Lawrence	952305	886295	66010	733978	218328
(9) Canadian_Archipelago	853214	853009	205	852767	447
(10) Hudson_Bay	1241127	1152343	88784	1029530	211596
(11) Central_Arctic	3148299	3215124	-66825	3206257	-57957
(12) Bering_Sea	118989	329544	-210555	246957	-127968
(13) Baltic_Sea	15543	19208	-3665	16	15528
(14) Sea_of_Okhotsk	477365	266483	210882	344508	132857
(15) Yellow_Sea	0	4017	-4017	0	0
(16) Cook_Inlet	5555	7180	-1624	12191	-6635

The main deficit to average is in Barents and Greenland Seas on the Atlantic side, and in Bering and Chukchi Seas on Pacific side.  The Canadian and Siberian sides are locked in ice, with sizable surpluses in Baffin and Hudson Bays, along with Okhotsk.  The differences with 2006 are similar, though resulting in a surplus.

Summary

There is no need to panic over Arctic ice this year, or any year.  It fluctuates according to its own ocean-ice-atmospheric processes and we can only watch and be surprised since we know so little about how it all works.  Judah Cohen at AER thinks the much greater snowfall in October will make for a very cold winter.  We shall see.

https://rclutz.wordpress.com/2016/07/06/warm-is-cold-and-down-is-up/

 

 

Two days ago I posted on Resurging Arctic Ice, and noted that most of the deficit to average was in Barents Sea and Hudson Bay.  Look what happened yesterday in Hudson Bay.

Now compare to the day before

2016 Arctic ice extent has now topped 12M km2, and continues to close in on the average for the last decade.

Sea Ice Index from NOAA is running more than 400k km2 behind. But the polar bears know the truth, and it has set them free.

 

The regrowth of Arctic ice extent was slower than usual until recently. After showing resilience in September, ending higher than 2007, ice growth lagged in October, but is now rapidly ramping up toward the averages.  The map above shows the lack of ice is mainly in Hudson Bay and Barents Sea.  Kara, Bering and Chukchi seas have all rebounded and everything else is locked in ice.

In the last 24 days, 2016 ice extent has grown by 123k km2 per day, compared to the 10-year average 79k km2 per day.  As of day 348, 2016 ice extent is ~3% less than average (2006 to 2015).  The chart also shows the variability of ice extent over the years during this season.  2015 was the highest ice recovery rate in the last decade, while 2007 was the slowest.  The chart also shows 2016 Sea Ice Index (SII) from NOAA has been lagging behind by more than 300k km2.

The table below shows this year compared to average and to 2007 for day 348.

Region	2016348	Day 348 Average	2016-Ave.	2007348	2016-2007
(0) Northern_Hemisphere	11762663	12168943	-406279	11501915	260748
(1) Beaufort_Sea	1070445	1069448	997	1062676	7769
(2) Chukchi_Sea	937738	937789	-51	725062	212676
(3) East_Siberian_Sea	1087137	1083777	3361	1053584	33553
(4) Laptev_Sea	897845	897832	12	897845	0
(5) Kara_Sea	742906	866952	-124046	800920	-58014
(6) Barents_Sea	271463	352281	-80818	236964	34499
(7) Greenland_Sea	494089	559862	-65773	488595	5494
(8) Baffin_Bay_Gulf_of_St._Lawrence	846064	813794	32270	793616	52448
(9) Canadian_Archipelago	853214	853007	207	852556	658
(10) Hudson_Bay	820629	1085867	-265238	1217263	-396634
(11) Central_Arctic	3200307	3211105	-10799	3186190	14116
(12) Bering_Sea	227611	250748	-23137	54836	172775
(13) Baltic_Sea	11782	10418	1364	2898	8884
(14) Sea_of_Okhotsk	297235	166142	131093	127576	169659
(15) Yellow_Sea	0	1278	-1278	0	0
(16) Cook_Inlet	3055	6601	-3546	48	3007

Most of the deficit to average is in Kara, Barents, Greenland Sea and Hudson Bay.  Central Arctic, CAA, Bering Sea and BCE are all average, while Okhotsk and Baffin Bay are showing surpluses.  Presently 2016 ice extent is 260k km2 greater than 2007 with large surpluses in BCE, Baffin, Bering and Okhotsk Seas.  Only Hudson Bay and Kara were larger in 2007.

There is no need to panic over Arctic ice this year, or any year.  It fluctuates according to its own ocean-ice-atmospheric processes and we can only watch and be surprised since we know so little about how it all works.  Judah Cohen at AER thinks the much greater snowfall in October will make for a very cold winter.  We shall see.

https://rclutz.wordpress.com/2016/07/06/warm-is-cold-and-down-is-up/

 

 

The growth of Arctic ice extent has been slower than usual this year.  After showing resilience in September, ending higher than 2007, ice growth lagged in October, and is only now ramping up toward the averages.  The map above shows the lack of ice is mainly in Hudson Bay, and the slow freezing of Kara and Barents Seas.  Everything else is locked in ice, except for some open water in Bering and Chukchi.

In the last five weeks, 2016 ice growth has surged twice, firstly from day 303 to 314, and then the current surge the last 10 days starting day 325.  The chart also shows the variability of ice extent over the years during this season.  2015 was the highest ice recovery rate in the last decade, while 2006 was the lowest.  The chart also shows Sea Ice Index (SII) from NOAA is lagging over 300k km2 behind.

There is no need to panic over Arctic ice this year, or any year.  It fluctuates according to its own ocean-ice-atmospheric processes and we can only watch and be surprised since we know so little about how it all works.  Judah Cohen at AER thinks the much greater snowfall in October will make for a very cold winter.  We shall see.

https://rclutz.wordpress.com/2016/07/06/warm-is-cold-and-down-is-up/

 

 

Researchers found that ice conditions in the 19th century were remarkably similar to today’s, observations falling within normal variability. The study is Accounts from 19th-century Canadian Arctic Explorers’ Logs Reflect Present Climate Conditions (here) by James E. Overland, Pacific Marine Environmental Laboratory/NOAA, Seattle,Wash., and Kevin Wood, Arctic Research Office/NOAA, Silver Spring, Md.   H/t GWPF

Overview

This article demonstrates the use of historical instrument and descriptive records to assess the hypothesis that environmental conditions observed by 19th-century explorers in the Canadian archipelago were consistent with a Little Ice Age as evident in proxy records.  We find little evidence for extreme cold conditions.

It is clear that the first-hand observations of 19th-century explorers are not consistent with the hypothesized severe conditions of a multi-decadal Little Ice Age. Explorers encountered both warm and cool seasons, and generally typical ice conditions, in comparison to 20th-century norms.

Analysis

There were more than seventy expeditions or scientific enterprises of various types dispatched to the Canadian Arctic in the period between 1818 and 1910. From this number, we analyzed 44 original scientific reports and related narratives; many from expeditions spanning several years. The majority of the data come from large naval expeditions that wintered over in the Arctic and had the capacity to support an intensive scientific effort. A table listing the expeditions and data types is located at http://www.pmel.noaa.gov/arctic/history. The data cover about one-third of the possible number of years depending on data type, and every decade is represented.

Our analysis focuses on four indicators of climatic change: summer sea ice extent, annual sea ice thickness, monthly mean temperature, and the onset of melt and freeze as estimated from daily mean temperature. Historical observations in these four categories were compared with modern reference data; the reference period varied, depending on data availability.  Both sea ice extent and the onset of melt and freeze were compared to the 30- year reference period 1971–2000; monthly means are compared to the 50-year period 1951–2000. Modern sea ice thickness records are less continuous, and some terminate in the 1980s; the reference period is therefore based on 19 to 26 years of homogeneous record.

Fig.1.

(a) Proxy record of standardized summer air temperature variation derived from ice cores taken on Devon Island. This proxy record suggests that a significantly colder climate prevailed in the 19th century. Shading indicates temperatures one standard deviation warmer or colder than average for the reference period 1901–1960 [Overpeck,1998].

(b) Historical monthly mean temperature observations compared to the 20th-century reference period 1951–2000. Sixty-three percent of 343 monthly mean temperatures recorded on 19th-century expeditions between 1819 and 1854 fall within one standard deviation of the reference mean at nearby stations (reference data from Meteorological Service of Canada,2002; and National Climatic Data Center,2002).

(c) Onset of melt observed by expeditions between 1820 and 1906 expressed as departures from the mean for the reference period 1971–2000. The period of melt transition observed by 19th century explorers is not inconsistent with modern values.

(d) Onset of freeze observed between 1819 and 1905 compared to the reference period 1971–2000. The onset of freeze transition is frequently consistent with modern values,but in some cases occurred earlier than usual. The incidence of an early onset of freeze represents the largest departure from present conditions evident in the historical records examined in this study. Melt and freeze transition dates for the reference period 1971–2000 were calculated from temperature data extracted from the Global Daily Climatology Network data base (National Climate Data Center, 2002).

Fig.2. The ship tracks and winter-over locations of Arctic discovery expeditions from 1818 to 1859 are surprisingly consistent with present sea ice climatology (contours represented by shades of blue). The climatology shown reflects percent frequency of sea ice presence on 10 September which is the usual date of annual ice minimum for the reference period 1971–2000 (Canadian Ice Service,2002). On a number of occasions,expeditions came within 150 km of completing the Northwest Passage, but even in years with unfavorable ice conditions, most ships were still able to reach comparatively advanced positions within the Canadian archipelago. By 1859, all possible routes comprising the Northwest Passage had been discovered.

Summary

As stated here before, Arctic ice is part of a self-oscillating system with extents expanding and retreating according to processes internal to the ocean-ice-atmosphere components. We don’t know exactly why 19th century ice extent was less than previously or less than the 1970s, but we can be sure it wasn’t due to fossil fuel emissions.

Explorers encountered both favorable and unfavorable ice conditions. This drawing from the vicinity of Beechey Island illustrates the situation of the H.M.S.Resolute and the steam-tender Pioneer on 5 September 1850 [from Facsimile of the Illustrated Arctic News,courtesy of Elmer E.Rasmuson Library,Univ.of AlaskaFairbanks].

After showing resilience in September, Arctic ice growth faltered in October. The graph shows MASIE ice extents in 2016 in comparison with other years and with SII.

Last year was above average recovery, while both SII and MASIE showed October 2016 well below average, and dropping down to 2007 levels.  Interestingly, MASIE and SII show virtually the same October average extent at 6.1M km2. This amount is 10% below the MASIE Oct. ten-year average, but that figure is 21% below SII ten-year average for Oct.

6.1M km2 is still higher than 2007 by 260k km2 despite the slower recovery this year. There is an anomaly in the 2007 record: a leap of almost 800k km2 on day 303, including E. Siberian Sea adding 460k km2 to more than double its ice extent on that day. Kara also jumped up 50% adding 100k km2. More about those two seas below.

The table shows by region the differences from ten-year MASIE averages for day 305, October 31.

Region	2016305	Day 305 Average	2016-Ave.
(0) Northern_Hemisphere	7283405	8865912	-1582506
(1) Beaufort_Sea	769445	998163	-228718
(2) Chukchi_Sea	276157	506472	-230315
(3) East_Siberian_Sea	600113	1001404	-401291
(4) Laptev_Sea	897773	897591	182
(5) Kara_Sea	162641	559477	-396837
(6) Barents_Sea	24522	120163	-95641
(7) Greenland_Sea	319983	446472	-126489
(8) Baffin_Bay_Gulf_of_St._Lawrence	262586	260072	2514
(9) Canadian_Archipelago	728911	782867	-53956
(10) Hudson_Bay	76561	90864	-14303
(11) Central_Arctic	3155443	3190140	-34696

Clearly in the table and in the image at the top, ice is missing mostly in the BCE region on the Asian side (Beaufort, Chukchi, E. Siberian) and in Kara and Barents on the European side.

What’s Up with Arctic Ice

For some answers let’s turn first to Dr. Judah Cohen of AER.  His analysis is thorough and interesting (here).  Excerpts:

Arctic sea ice reached its annual minimum on September 10th. Despite an initial spurt of ice growth, overall Arctic sea ice has been expanding at an anemic rate. One area to note on the North Atlantic side is in the Barents-Kara Seas, where negative sea ice anomalies have been growing (Figure 13). Recent research has shown that regional anomalies are important and the sea ice region most highly correlated with the winter AO is the Barents-Kara seas region where low Arctic sea ice favors a negative winter AO. Given that sea ice is running well below normal, this currently favors further expansion Eurasian snow cover in the coming weeks, followed by a strengthened Siberian high and a weakened polar vortex/negative AO this upcoming winter.

Sea ice anomalies also remain well below normal in the East Siberian, Chukchi and Beaufort seas. This could favor positive geopotential height anomalies near Alaska forcing downstream troughing and cold weather across eastern North America.

Additional context is provided by Ted Scambos in an article at Discover Magazine (here).  Excerpts below.

Arctic sea ice has been been growing much more slowly than average during October. Its geographic extent is now in a rough tie with 2007 and 2012 for the lowest in the satellite record for this point in the year.

According to Ted Scambos, a senior research scientist at the National Snow and Ice Data Center, two big Arctic storms in August contributed significantly to the very low minimum extent in September. They probably did this by “breaking up the ice and stirring a trace of warmth up from deeper levels (5-10 meters below the surface),” Scambos says.

Not too long after the storminess subsided, the surface water refroze fairly quickly, accounting for the rapid expansion of sea ice after the low point in September sea ice

That rapid freeze-up happened in the heart of the Arctic Ocean, where temperatures would normally be coldest. Meanwhile, more at the periphery — particularly in the Barents, Kara and Laptev seas — “the ice edge has barely changed,” says Julienne Stroeve, who also serves as a senior research scientist at NSIDC.

Sea ice has expanded somewhat in the Beaufort Sea, off Alaska’s north coast. But the edge is still far short of the long term average in the region.

Why has Arctic sea ice been growing so slowly in the past couple of weeks? Once again, Scambos thinks the warm sea surface temperatures that have been retarding ice growth also have been warming the air directly above the water. 

“It is not surprising that it is extremely warm in the weeks following near-record minimums [in sea ice extent], because open water beneath the atmosphere buffers the air temperature at near the freezing point for several weeks until several centimeters of ice are formed,” Scambos says. “In this case, I would say that the high air temperature anomaly is an effect, not a cause, of slow sea ice growth, and that the leading cause is ocean temperature.”

What’s the Winter Outlook

Dr. Judah Cohen provides his seasonal forecast here.

Snow cover advance across Eurasia continued consistently above normal for the entire month of October. Also because much of the advance has occurred at latitudes south of 60°N, the snow advance index is also well above normal. Above normal snow cover extent, especially south of 60°N, favors a strengthened Siberian high and a weakened polar vortex/negative AO this upcoming winter with cold temperatures across the continents of the NH.

Predicted winter surface temperature anomalies for the United States Dec-Jan-Feb 2016/17 in degrees Fahrenheit. The model is forecasting colder than normal temperatures for much of the Eastern United States, with warmer than normal temperatures for the Western United States. The model uses October Siberian snow cover, sea level pressure anomalies, predicted El Niño/Southern Oscillation anomalies, and observed September Arctic sea ice anomalies. October Siberian snow cover has so far this month advanced at an above normal rate. This is an indication of an increased probability of a weakened polar vortex or a sudden stratospheric warming, and a predominantly negative Arctic Oscillation during the winter and cold temperatures – especially east of the Mississippi. This is a preliminary forecast and not the official winter forecast as the model requires full monthly values for snow cover and sea level pressure anomalies. The forecast will be updated next month. Current forecast produced on October 19, 2016.

Summary

Both Cohen and Scambos explanations are consistent with the lack of ice both in BCE on the Asian side (Beaufort, Chukchi, E. Siberian), and in Kara and Barents on the European side.

Warm ocean water reduces ice extents, the air is warmed and moistened, and then snowfall increases. The conditions for winter ice formation are shaping up, though somewhat later than usual, perhaps because of August storm activity.

Lastly, it’s important to realize that two weeks is a short period of time, and Arctic sea ice could start forming up at a more normal rate for this time of year. In fact, that’s what Scambos predicts: “Now I expect that sea ice growth will take a more typical path (typical for the past 5-8 years, at least).”

One more time: Remember the 3 Ws when it comes to Arctic ice extents.  Firstly it’s the Water, and then the Wind circulation, and the Weather.  Air temperatures are an effect not the cause.

For more on this see:

Arctic Sea Ice: Self-Oscillating System

Arctic Not a Refrigerator

August 2016 was the final report of the Sea Ice Prediction Network (SIPN) before the actual September monthly extent is reported by NOAA Sea Ice Index (SII). The report (here) gave this overview:

This month the median pan-Arctic extent Outlook for September 2016 sea ice extent is 4.4 million square kilometers (km2) with quartiles of 4.2 and 4.7 million km2, which is slightly higher than July’s value (4.3 million km2) (See Figure 1 in the full report, below). If the median Outlook should agree with the observed estimate come September, this year would be the third lowest September in the satellite record. The spread in the Outlook contributions narrowed slightly from July to August, with an overall range this month of 3.7 to 5.2 million km2.

The chart shows the September monthly sea ice extents from NOAA and MASIE. Both datasets show 4.5 M km2, above what was predicted, about 200k km2 higher than 2007.

In MASIE, September 2016 finished as the fourth lowest, ahead of 2012, 2007 and 2008, slightly behind 2011.

Some had anticipated a late Arctic cyclone might again produce a lower number, as it did in 2012. But as the chart shows, 2012 is looking increasingly like an outlier, interrupting a steady recovery of ice extents since 2007.

 

Despite what you may be hearing, Arctic ice is not presently declining, a big disappointment to fear mongers. Something happened to cause a rapid decline in the decade 1998 to 2007, but since then the ice has been stable or slightly rising.

The analysis below comes from the MASIE dataset, whose managers have no stated position on global warming, climate change, or the future of Arctic ice. They simply report daily ice conditions for the safety of ships operating in Arctic seas. It is the highest resolution, most accurate report of daily ice conditions. MASIE historical records became available once NSIDC confirmed that the records have reasonable consistency starting with 2006.

Big Picture Shows Recovery from 2007 Low

Arctic ice extents are cyclical with maximums occurring in March and the annual minimums in September. Autumn snowfall and winter weather affect the March ice, and September varies with warm and salty water circulations, cloudiness affecting brightness, and stormy weather breaking and compressing ice. The annual average of ice extent factors in fluctuations over the entire cycle.

Since we are at the end of the melt season, the chart below takes 12 month averages starting Oct. 1 to display average annual ice extents for the last 11 years.

The minimum occurred in 2007 at ~10.4 M km2 and all years have been higher than that, including 2006, 2012 and 2016 virtually tied at ~10.7 M km2. The trendline is descriptive, not predictive; that is, the line serves only to show the pattern in this brief history, the future could go higher or lower with equal uncertainty.

It should be noted that the variability is quite constrained within +/- 0.4 M km2, or +/- 3% of the annual average. Also 5 years are above average, and 6 years are below.

September Ice Minimums

The chart below shows comparative measures of September ice extents.

The red line is September 2007, which was the lowest in the last 10 years, except for 2012 which was hit by the great Arctic Cyclone.  More importantly, 2007 had the smallest annual average ice extent in the MASIE record (since 2006).  The blue line is the ten-year average for days in September (2006 to 2015 inclusive).  MASIE 2015 is in purple, MASIE 2016 in green, and 2016 NOAA SII (Sea Ice Index) is in yellow.

While the minimums all occurred days 260 to 262, 2007 extents were already trending lower, and presently the other measures are converging above average.  With SII virtually tied with MASIE, that index will also be showing a September average ~ 4.5 M km2.

2016 is now slightly above average, having gone below the average annual minimum (4.6 M km2 on Sept. 16) for 17 days before regaining the lost ice.

The table below shows the locations of ice among the various seas making up the Arctic Ocean. Day 273 is Sept. 30 most years; 2016 being a leap year is one day later. So the official 2016 results will benefit from an additional day of ice extent exceeding 5M km2.

Region	2016273	Day 273 Average	2016-Ave.	2015273	2016-2015
(0) Northern_Hemisphere	5128960	5014059	114901	5183385	-54426
(1) Beaufort_Sea	376071	574043	-197972	530396	-154325
(2) Chukchi_Sea	427460	212714	214746	329362	98098
(3) East_Siberian_Sea	323001	329489	-6488	265744	57257
(4) Laptev_Sea	295732	162254	133477	165663	130069
(5) Kara_Sea	163	43464	-43301	45328	-45166
(6) Barents_Sea	271	24142	-23871	1445	-1174
(7) Greenland_Sea	194462	256519	-62057	256733	-62271
(8) Baffin_Bay_Gulf_of_St._Lawrence	50141	49107	1034	71775	-21635
(9) Canadian_Archipelago	347668	356314	-8646	352788	-5120
(10) Hudson_Bay	0	4953	-4953	15485	-15485
(11) Central_Arctic	3112850	2999948	112902	3147524	-34674

2016 is above average with deficits mainly in Beaufort, Kara, and Greenland seas, offset by surpluses in Chukchi, Laptev and Central Arctic.

Summary

Those claiming global warming is proved by declining Arctic ice are losing that line of evidence. Not only has it stopped declining, the evidence is growing that it varies over quasi-60 year cycles because of changes in water circulations, wind and weather. And some researchers think that the ice may continue to grow up and up in the near future.

For more on Arctic Ice Datasets:

A Tale of Two Indices

Ice House of Mirrors

Footnote:

Crystal Serenity is planning for more future Arctic cruises, while Russia is planning for more icebreakers.

MASIE: “high-resolution, accurate charts of ice conditions”
Walt Meier, NSIDC, October 2015 article in Annals of Glaciology.

I’ve been waiting for September 30 results to compare the monthly average for this year with previous ones.  But the remarkable rate of refreezing in the Arctic needs reporting.  MASIE counts ice extent using 40% coverage of 4k km2 grid cells, making it the highest resolution dataset.  As well, it incorporates estimates from satellite passive microwave sensors, supplemented with satellite imagery and reports from buoys and ships.

The red line is September 2007, which was the lowest in the last 10 years, except for 2012 which was hit by the great Arctic Cyclone.  More importantly, 2007 had the smallest annual average ice extent in the MASIE record (since 2006).  The blue line is the ten-year average for days in September (2006 to 2015 inclusive).  MASIE 2015 is in purple, MASIE 2016 in green, and 2016 NOAA SII (Sea Ice Index) is in yellow.

While the minimums all occurred days 260 to 262, 2007 extents were already trending lower, and presently the other four measures are converging.  Since the September rate of regaining ice was at a decadal high in 2015, it is remarkable for 2016 to be improving on that.  Since 2007 will end the month close to where it is now, we can project that 2016 monthly average will be considerably higher, likely to exceed also 2008.  With SII virtually tied with MASIE, that index will also be showing a September average well over 4.4M km2.

Summary

With 2016 ice extents surging, we can project that Arctic ice has continued on a flat or slightly increasing trendline with no evidence of a decline since 2007.

 

Why the Discrepancy between SII and MASIE?

The issue also concerns Walter Meier who is in charge of SII, and as a true scientist, he is looking to get the best measurements possible. He and several colleagues compared SII and MASIE and published their findings last October. The purpose of the analysis was stated thus:

Our comparison is not meant to be an extensive validation of either product, but to illustrate as guidance for future use how the two products behave in different regimes.

The Abstract says:
Passive microwave sensors have produced a 35 year record of sea-ice concentration variability and change. Operational analyses combine a variety of remote-sensing inputs and other sources via manual integration to create high-resolution, accurate charts of ice conditions in support of navigation and operational forecast models. One such product is the daily Multisensor Analyzed Sea Ice Extent (MASIE). The higher spatial resolution along with multiple input data and manual analysis potentially provide more precise mapping of the ice edge than passive microwave estimates. However, since MASIE is based on an operational product, estimates may be inconsistent over time due to variations in input data quality and availability. Comparisons indicate that MASIE shows higher Arctic-wide extent values throughout most of the year, largely because of the limitations of passive microwave sensors in some conditions (e.g. surface melt). However, during some parts of the year, MASIE tends to indicate less ice than estimated by passive microwave sensors. These comparisons yield a better understanding of operational and research sea-ice data products; this in turn has important implications for their use in climate and weather models.

http://www.igsoc.org/annals/56/69/a69a694.pdf

The whole document is informative and worth the read.
For instance MASIE is described thus:

Human analysis of all available input imagery, including visible/infrared, SAR, scatterometer and passive microwave, yields a daily map of sea-ice extent at a 4 km gridded resolution, with a 40% concentration threshold for the presence of sea ice. In other words, if a gridcell is judged by an analyst to have >40% of its area covered with ice, it is classified as ice; if a cell has <40% ice, it is classified as open water.

The fact that MASIE employs human judgment is discomforting to climatologists as a potential source of error, so Meier and others prefer that the analysis be done by computer algorithms. Yet, as we shall see, the computer programs are themselves human inventions and when applied uncritically by machines produce errors of their own.

The passive microwave sea-ice algorithms are capable of distinguishing three surface types (one water and two ice), and the standard algorithms are calibrated for thick first-year and multi-year ice (Cavalieri, 1994). When thin ice is present, the algorithms underestimate the concentration of new and thin ice, and when such ice is present in lower concentrations they may detect only open water. The underestimation of concentration and extent of thin-ice regions has been noted in several evaluation studies. . .Melt is another well-known cause of underestimation of sea ice by passive microwave sensors.

The paper by Meier et al. is a good analysis, as far as it goes. In a post NOAA is Losing Arctic Ice I showed the gory details and brought the comparison up to date.

A year ago MASIE results showed clearly that the decline of ice prior to 2007 had stabilized and increased a bit.  The graph below displays the plateau of annual average ice extents based on October 1 to September 30.  In 2 weeks we can add 2016 and see how the trend changes.

The monthly average extent for September is the climate statistic, since daily reports vary greatly due to weather, ice movements and darkening conditions, just some of the factors making it difficult to measure anything in the Arctic.

Halfway through September, we can compare extents for day 260, the average day for annual minimums. The table below shows MASIE extents in M km2 on day 260 for significant years in the last decade.

Arctic Regions	2007	2012	2014	2015	2016
Central Arctic Sea	2.67	2.64	2.98	2.93	2.92
BCE	0.5	0.31	1.38	0.89	0.52
Greenland & CAA	0.56	0.41	0.55	0.46	0.45
Bits & Pieces	0.32	0.04	0.22	0.15	0.31
NH Total	4.05	3.4	5.13	4.44	4.20

The main difference between 2007 and 2016 is more ice in Central Arctic. 2015 is slightly higher because of BCE (Beaufort, Chukchi, E. Siberian combined), though the Bits and Pieces are higher now, most of it in Laptev this year.

The rate of refreezing in the next 2 weeks should keep 2016 well ahead of 2007. The average gain of ice from now to Sept. 30 is 32k km2 per day, or 412k km2 added to the day 260 extent. In 2007 the rate was the decade’s lowest: only 3k per day for 41k km2 added by end of Sept. Last year 2015 was one of the fastest recoveries, almost twice the average.

Conclusion

It looks likely that 2016 September extent average will finish higher than 2007 and close to 2008 and 2011.  It is unlikely to catch 2015.  But who knows?

No one knows what will happen to Arctic ice.

Except maybe the polar bears.

And they are not talking.

Except, of course, to the admen from Coca-Cola