Sea ice extent update 28: riding the seesaw

I'm regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2006-2009. The IJIS graph is favoured by almost everyone, probably because it looks so nice compared to other graphs (like the one by Arctic ROOS, the University of Bremen and the Danish Meteorological Institute). All the years have a nice colour of their own which makes it easy to eyeball the differences between trends. Most of the betting on minimum SIE is based on the IJIS data. NSIDC has a good explanation of what sea ice extent is in their FAQ.

September 4th 2010

It is the time of the year when emotions of Arctic sea ice aficionados swing to and fro, where expectations falter and get reborn again the next day, where the mood swings of the Arctic ice are those of an ice queen on steroids and confirmation biases get tested and challenged till they start to crack. In short, we're sitting on the seesaw. And loving every minute of it, like the kids we are.

It looked like the fat lady was about to sing the finale when the extent started to decrease very slowly and even increase a bit, but all of a sudden the orchestra decided to continue playing. Andante, ma non troppo.

And thus 2010 continues its hunt for the 5 million square km mark, after having surpassed 2005 and 2009. But it's a slow hunt. We're on the seesaw. It can continue a while longer or it can be over in a split second.

There's no need to talk about the +9,844, -4,219, -18,906, +2,969, -28,125 and -58,594 square km extent decreases and increases in the days since the last SIE update. Let's look at some statistics, graphs and maps.

The current difference between 2010 and the other years is as follows:

• 2006: -713K (13,784)
• 2007: +666K (14,688)
• 2008: +321K (38,219)
• 2009: -134K (15,180)

Between brackets is the average daily extent decrease for the month of September until each year's respective date of minimum extent. 2010's average daily extent decrease for September is currently 27,917 square km per day.

If 2010 loses as much sea ice extent as...

• 2006 did after this date it will bottom out at 5.07 million square km.
• 2007 did after this date it will bottom out at 4.92 million square km.
• 2008 did after this date it will bottom out at 5.03 million square km.
• 2009 did after this date it will bottom out at 5.11 million square km.

Here's the IJIS sea ice extent graph:

 

The Cryosphere Today sea ice area anomaly has gone down from 1.439 million square km in the last SIE update to 1.589 million square km and sea ice area overall is starting to enter record territory. 2007 ended just below 3 million square km, 2008 just above it, and 2010 is currently at 3.2 million square km. The decrease in the Arctic Basin has continued some more and is well below last year's trough. Sea ice area in the East Siberian Sea and the Laptev Sea is not far from zero now. SIA in the Canadian Archipelago and Greenland Sea has been increasing slightly, probably because of all the ice transport and landfast ice breaking off. Here's the CT sea ice area anomaly graph:

The relatively large decrease in sea ice area and the seesawing of extent have had some interesting effects on our compactness graph (that shows the ratio between CT area data and IJIS extent data). It hit a bottom of 60.97% on the 1st of September and I'm not sure if it'll go any lower although it still hovers around 61%. One day of extent increase and a big area decrease could drive it below 60%. Here's the graph:

What does that tell us?

Despite the late bottoming out (2007, 2008 and 2009 all had their minimum compactness between August 14th and 20th) there still is a lot of divergence of the ice going on, whereas compaction is the norm around this time in the melting season. But the norm doesn't seem to apply to the very thin, ultra-mobile ice of 2010.

Perhaps we will see more of this in the coming years: artificially high extent numbers because the ice pack is disintegrating into a multitude of mini-floes that move every which way. Obviously, compaction is much more effective than melt to reduce extent at this time of the year, when insolation and air temperature get ever lower.

But despite all this inevitable divergence 2010 is still poised to go below 5 million square km. Amazing. Perhaps the coming La Niña can finally offer some real recovery next year, but July and August will have to be very cloudy again! I truly believe the ice pack has never been as vulnerable as it is now. I mean, look at this:

 

ECMWF is still forecasting a high (sort of) holding onto its position over the Canadian Archipelago, which is reflected in the Arctic Oscillation Index that shows a negative AO again (indicating 'dominance' of high-pressure areas in the Arctic) . Whether this all-important aspect of the end zone of this year's melting season remains favourable to extent decreasing remains to be seen on a a day-to-day basis. In the current forecast the high is slowly shifting over to the wrong side of the Arctic (around the 14th of September), which would spell end of melting season. Here's an animation of the forecast:

 

Another related conclusion I drew from the End Zone-series is that the melting season ain't over as long as PIPS ice displacement maps are showing big arrows pointing in more or less the same direction. If we look at the images from the past week we see a few big arrows at the beginning of the month, all pointing towards Fram Strait. These arrows have become a bit smaller in the past two days and a bit more diffuse. Keep an eye on this important indicator:

 

 Keep enjoying that Arctic seesaw!

TIPS - Other interesting blog posts and news articles concerning the Arctic and its ice:

Patrick Lockerby is taking it slow with regards to quantity, but quality is never the issue with this guy. His Arctic Ice September analysis has been out for a few days, but it's here, in case you missed it.

Gareth Renowden is also keeping a close watch on current developments. His latest piece on the Arctic sea ice is called Long way around the sea.

Hot from the press is this must-read article by Mauri Pelto on the very interesting Humboldt Glacier.

Our Norwegian circumnavigating friends have left Russian waters and are sailing towards Alaska. To celebrate they have changed their underwear, and are about to swap their Russian crewmate for a French one. I'll have more on their voyage as soon as they start nearing the NWP.

People who would like to keep a closer eye on that Beaufort high are well-served at Marc de Keyser's excellent blog and his posts that analyze meteorological conditions along the route the Northern Passage is following.

Comments

[Gas Glo]

Revision makes it third highest one day fall in September:

Record falls in (or partly in or later than) September are:

1 day falls
15/09/2003 -96719
07/09/2008 -68437
07/09/2010 -66093
18/09/2004 -61563
03/09/2010 -58594

2 day avgs
01/09/2008 -54453
15/09/2003 -65234.5
04/09/2010 -56015.5
07/09/2010 -54453
01/09/2003 -53906.5
05/09/2008 -50703

3day avgs
07/09/2010 -65234.5
02/09/2008 -55260.33333
07/09/2010 55000
16/09/2003 -46146
06/09/2007 -44323
07/09/2008 -43020.66667

4day avgs
07/09/2010 -54609.25
01/09/2008 -51367.25
07/09/2008 -46796.75
06/09/2007 -42500
01/09/2002 -36914

5day avgs
07/09/2010 -55406.2
02/09/2008 -47781.2
08/09/2010 -42312.4
01/09/2002 -37062.6
07/09/2007 -36062.4
04/09/2003 -35437.6

6day avg
07/09/2010 -50859.33333
01/09/2008 -44218.83333
01/09/2003 -38203.16667
09/09/2008 -36536.33333
05/09/2003 -34922

7 day avg
01/09/2008 -49665.28571
07/09/2010 -43169.57143
01/09/2002 -41785.71429
08/09/2008 -34598.14286
01/09/2007 -33816.85714

2010 features pretty prominently in all of those so I think I can drop my note about cherrypicking the averaging period. The falls in September this year do look significant.

[Neven]

Toby, I'm trying to put out a new SIE update later today, but it has something to do with the weather forecast.

[Gas Glo]

Apologies 2 day average ending 1 September 2008 is the record at -66172 not (-54453 as posted above).

[Kevin McKinney]

Thanks for the correction, Gas Glo, I noticed--shall I call it an anomaly?--but got hold of the wrong end of the stick and suspected a typo in the 2003 number. . .

[Kevin McKinney]

The question of compaction vs. melt right now is an interesting one. Looking at the CT concentration map, "Eyeball Mark I" reported compaction going on. . . then I read Lodger's analysis of the CAPIE numbers, which also seems fairly convincing. Of course, as physical processes you can (and, I'm sure, often enough do) have both happening simultaneously. Quite likely we do right now.

As mentioned on another thread (IIRC), the IJIS-JAXA and NSIDC methodologies differ in terms of spatial resolution--also in terms of temporal resolution, right? (5-day versus 2 day moving averages?) (Although if it were 5 days vs. 2, I'd expect extent to be decreasing faster now, and the CAPIE number to be rising, not dropping.)

Ah well, I'm clearly spinning my wheels here. Still, it's an interesting discrepancy.

[Neven]

Kevin, I've been thinking about that too. How can CAPIE remain so low, when 'tis the season to be compacted? I think we've got convergence on the Pacific side (and a bit melt because the waters are relatively warm over there), and divergence on the Atlantic side, with some more melting. It's weird. This year looks weird.

[Steve Bloom]

You're on thin ice with that speculation, Neven. :)

[Steve Bloom]

L. Hamilton, my impression from various scientist comments I've seen over the past few years is that it was anticipated that the area to the north of Nares Strait and in and north of the archipelago would constitute a sort of sea ice refugium that would persist for some years after the central basin starts melting out. Based on the behavior of this year's ice, I think it's clear that the archipelago will serve in no such role. Without that, the remaining area above Nares Strait starts to look like the sort of thing winds could blow to the east and so to melting in the Fram Strait.

[Steve Bloom]

Joe Romm has an excellent post describing and placing in context new results on the history of Arctic sea ice.

[Steve Bloom]

Below is a link to a public copy of the "History of sea ice in the Arctic" paper discussed by Romm. It's a review and synthesis paper featuring many of the big names in the field.

http://www.cgd.ucar.edu/oce/mholland/papers/Polyak_2010_historyofseaiceArctic.pdf

[Christoffer Ladstein]

Before I will find my way to the sheets (past 11 PM Norwegian time), I am confident of wakening up to a SIA far below the 5 mill. "milestone". 4.975.000 will be a close estimate.
These are exciting days!
Not only the Arctic is melting away, also the Norwegian glaciers are struggling hard, they've never measured such low quantity of summersnow as this year.
So no matter how fast or not the Ice covering Greenland, Canada, Norway, Iceland is vaporizing, the sealevel is bound to rise!

[Steve Bloom]

Hmm, Christoffer, it seems like it was only yesterday when the growth of the Norwegian maritime glaciers was being touted in the denialosphere as evidence of cooling.

I have a question for the more informed: I don't frequently look at the CT graphics, but when I did today for the first time in a while it appeared that we're only about 120K above the 2007 record low area. Can that be right? I had assumed several weeks back that all of the metric records were far out of reach for 2010. This must have been discussed somewhere here, so please excuse me for missing it.

[Artful Dodger]

Steve, I'll have a go at your question. This table compares minimum September CT Sea Ice Area to the Sep 6, 2010 minimum of 3.1098619 M km^2:

Year DD minSIA 2010-Year
---- -- ------ ---------
2006 23 4.0169  -907,057
2007 07 2.9194  +190,423
2008 08 3.0036  +106,306
2009 09 3.4246  -314,736

You can see that the 2007 and 2008 minimums are still below the latest SIA for 2010.

[Steve Bloom]

Thanks, Dodger. So ~190K as of the 6th, but does that go with the graphic I looked at today? IOW is it showing a couple more days of loss to put things closer to my eyeball result of ~120K? In any case it's good to know I wasn't fundamentally out in left field. Also, where are those numbers kept on the CT site? I found the archive of graphics easily enough, but no numbers (at least not in an easily accessible form). Also, do we know for a fact that the graphics and numbers are updated at the same time? I was eyeballing this graphic, BTW: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.area.arctic.png

[Artful Dodger]

Steve: The CT Sea Ice Table is here. Note that the Date is expressed as "Year.Frac". If you're not familiar with that usage, read about the YEARFRAC function in the help for your Spreadsheet.

Basically, drop the Integer part of the number, and multiply the fractional part by 365 to get the Day of the year (similar to MODIS dates). Be warned that the Date produced is for Midnight at the end of that day (since the origin CT uses for YEARFRAC is Jan 1, 00:00 hrs). So just check for Date alignment errors when comparing CT data with other sources.

[me.yahoo.com/a/nSjChi4X3vr8X3DRw93GkY1.cerja.8nvWk-]

Steve, the data is here: http://arctic.atmos.uiuc.edu/cryosphere/timeseries.anom.1979-2008

[Steve Bloom]

Great, thanks to both of you. So since I don't think I could be off as much as ~70K in eyeballing the graphic, either the graphing software's not very precise or the graph includes another couple of days of data. Since the difference is about right for those two days, it's hard to tell which. In any case, if the 2010 ice performs from the 6th to 13th as it did from the 30th to the 6th, we have a new winner. Likely it won't do quite that well (I suppose I should be saying poorly rather than well), but with another couple of weeks available for further reductions I'm betting on it (figuratively speaking).

[Evilreductionist.blogspot.com]

Christopher Ladstein,

Almost bang on. :)

4,977,344

We could come close to 2008 - if we lose the average for the last 5 years, we lose another 100,000 or so. But if we push the limits and the melt season lasts until late September, 200,000 plus is possible.

[ThomasE]

Another site with stunning graphs depicting the last 2000 years of temp history in the arctic. The hockey stick shape emerges stronger than ever.

http://climateprogress.org/2009/09/03/science-study-hockey-stick-human-caused-arctic-warming-overtakes-natural-cooling/