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

[Jon Torrance]

Updating a view of things I gave some weeks ago, if the CT area/JAXA extent ratio now were the same as for this date in 2009, then our current CT area would translate into a JAXA extent of 4.76 million square kilimeters. There's certainly plenty of potential for compaction, if that's what the weather decides to produce.

[L. Hamilton]

From eyeballing the NSIDC graph, it looks like they currently see extent slightly above 5 million. Some other NSIDC numbers for context:

1979-2009 September mean, 6.63

Projecting from a *linear* decline over 1979-2009, Sep 2010 would be 5.37

Projecting from a *quadratic* decline over 1979-2009, Sep 2010 would be 4.78

So if the current NSIDC value really is around 5, this month is headed closer to the quadratic than the linear prediction.

[JackTaylor]

Neven, THANKS for such a quick and complete update after having been gone for a few days. It's nice to have a blog with minimal political bickering & ad hominem.

Just wanted to say it before you may do an Update 30 and sign-off for the year.

In a minute posting a new animation, linked in the End Zone 5 sea ice concentration post.

[Neven]

Jon, indeed. Either it compacts and extent goes below 5 million, or it doesn't compact and there's a lot less thick ice next year. I like the way you compare the compactness number to 2009. If it stays this low I might do a separate blog post on it. Either way, it was the thing that struck me most after 3 days of no sea ice monitoring.

Larry, I don't know what a quadratic projection is, but I've seen some of Tamino's graphs on that, and I kind of 'feel' what it means. :-B Thanks for the info.

Jack, I'm pleasantly surprised to see that up till now I haven't had to edit or delete one single comment. Minimal linking on the other side helps a lot in that regard. I hope it stays this way till the end of the season. Thanks to you too for that animation (gonna watch it now).

[r w Langford]

"Our Norwegian friends"--recorded water temperature of 9 degrees celsius in the Chukchi sea today. Heading toward the NWP to be the first people to transit both passages in one year. What a record and a place in the Arctic history books. Here's wishing them good winds and weather.

[Phil263]

Neven

Thanks for that excellent, informative and ... lyrical update. Great job!
Now that 2010 is in third place, the headline " 2010 higher sea ice minimum shows that arctic ice is recovering" has been "stolen" from WUWT. We can relax !!!!

[Neven]

Thanks, Phil. Below 5 million square km would be even better.

I'm extremely curious to see what Watts will come up with now that Goddard has been thrown under the bus.

[Anu]

5,190,313 sq km

Another 55,312 sq km extent loss tonight.

Warm waters, weird winds, thin thickness - grab your popcorn now and settle in for the surprise ending of the movie.

[Artful Dodger]

Anu: Yeah, I'd guess most of that Ice was about 10 cm thick when it melted out. Spreading will do that. Ball park guess - I'd say there's another 300K sq.km. of 10 cm sea ice other there just about to go, if the winds keep spreading the pack. Compaction doesn't seem viable right now due to the thin rotten, soddard-ice.

[Steve Bloom]

Is there enough clear sky to get a satellite view of the compacted ice mass?

[Artful Dodger]

Steve: Sure, there's lots of patches of visibility throughout the Arctic. Start with the index map from Sep 4, and look for the "red" sea ice and ignore the "white" clouds. Click on any grid square to open it as a single image, and you'll have a 1 million sq. km area to view. Zoom in up to 250m resolution when you what to examine an area closely. You can also switch back to True Color, or view the same day from either 'Terra' or 'Aqua' satellites (clouds move a little, as Aqua trails in Orbit).

HINT: On Sep 4, you can see parts of the open patch near the N. Pole at 165 W, 87 N (note that this is an area of < 30% concentration)... I estimate this to be within 270 km of the Pole. Happy viewing! and let us know what you find.

[Charles Wilson]

What you need to watch is the Bering Strait Water - - just about to contact the remaining Pack in the most vulnerable part between those 2 arms. See: DMI's SST (click Arctic): http://ocean.dmi.dk/satellite/index.uk.php.

>> Seperate note: found a 3rd Numeric Data site @ bottom of This page: www.nersc.no/main/index2.php -- gives Daily numbers. Other two are
Cryo/ijis AREA: http://arctic.atmos.uiuc.edu/cryosphere/timeseries.anom.1979-2008
JAXA/ijis EXtent: http://www.ijis.iarc.uaf.edu/seaice/extent/plot.csv.
Topex has the ONLY comparison of SSMI & AMSR-E data on the same Graph: on row #2 from the Top: http://arctic-roos.org/forecasting-services/topaz/topaz-model-forecast
Pity their legend switched the two: AMSR-E should be the lower one.
DMI & Norsex/Nansen use the SSMI data.
Note: Nansen retains the all-time low of the previous algorithm - - which is adjusted UP 10% by Norsex/Arctic Roos (which Nansen runs: 2010 numbers are identical). Note this confirms NSIDC's claim that the New Algorithms mis-match with Previous years. Bremen also increased Older years.
>> Maybe we ought to add 10% to JAXA & Cryo 2007,8,& 9, numbers.

[FrankD]

Charles,
Thanks for the good tip on SST - even if the increase is slight, it does seem rather amazing to see Bering Strait temperatures still rising in September. That doesn't auger well for that side of the pack.

Your link is broken though. Should read: http://ocean.dmi.dk/arctic/satellite/index.uk.php

[L. Hamilton]

NEVEN;
'Larry, I don't know what a quadratic projection is, but I've seen some of Tamino's graphs on that, and I kind of 'feel' what it means.

Sorry for giving numbers with no interpretation, here's another try: Suppose, before the 2010 melt season started, we entertained 3 hypotheses.

* Recovery. The past few years have been anomalous; it's more likely we will see values drifting back toward more usual values in the future. Under this "regression toward the mean" hypothesis, we might have expected 2010 to finish closer to the 1979-2009 mean, which is 6.63.

* Steady decline. We see a statistically significant downward trend over 1979-2009. If this downward trend continues *at the same rate*, we might expect a September mean around 5.37.

* Steepening decline. The past three years went lower than anything before, so maybe the rate of decline is getting steeper, hence better approximated by a quadratic curve instead of a straight line. Then we might expect September to be about 4.78.

Looking at the NSIDC graph, I think we're slightly above 5 right now. If so, that suggests the final September mean is likely to be closer to the "steepening decline" than the "steady decline" hypothesis. And nowhere near the "recovery" hypothesis.

Tamino recently did a nice job presenting this quadratic version. Somebody else went one better and suggested a logistic curve (S-curve, which falls steeply like the quadratic in the middle, but unlike the quadratic does not crash all the way to zero).

If I were to go one better than a logistic curve, I might suggest an asymmetrical S such as Gompertz. But these exercises are abstract, looking at numbers not the ice which this blog does so well.

[Neven]

Larry, I'm feeling you, man. ;-)

But seriously, thanks for the explanation about different statistical approaches. If I'd be a smart bunny I'd do a blog post on it with different graphs.

[Werther]

4 september 2010:
Looking at the CT low colour level extent map, it seems to me that there is just 2 maybe 2,5 million of more or less congruent sea ice cover left, pressed against the Archipelago and Greenland. A comparable surface consists of floating debris, that probably wouldn’t resist two or three weeks of arctic dipole july weather.
In my opinion this years’ summer melt has severely contributed to the demise of all summer sea ice in the arctic. Like there is still some ice left in the McClintock bay and the Gulf of Boothia, there will be some pockets of sea ice left in the basin within three or four years, grinding against the rocky outcrops of Ellesmere.
And what about Greenland? Two days ago, the Uni of Delft let us know that the land-ice is melting twice as slow as up to now calculated. At first I angrily thought that the dutch media were tricked again by the denialosphere. Later I read that the Delft engineers had introduced a factor on eath-crest rebound under the icesheet, making up for post-ice-age and recent melt related isostatic movement. Corrected by that, calculations based on Grace gravity measurements led to half the melt assumed since 2002. Apart of the bad PR (wrong again; so don’t worry much) it is interesting; I wonder for two years why an accumulated melt in Greenland between 250 and 500 Gt (2005 I think) results in just 1,5 mm sea level rise a year extra (totaling 3,4) at the moment. Delft may be right, but that doesn’t change what’s going on; it’s just going to take a little longer….

[Glacierchange.wordpress.com]

The compaction index is very interesting, This will require more energy in the freezeup process. Werther the majority of ice loss from GIS is via ice discharge not melting. For Helheim and Jakobshavn for example the ice discharge accounts for more than 90% of the loss. For others like Petermann, much smaller discharge it is the other way around mostly melting, in that case basal melting. Basal melting increases still indicate either more meltwater available or warmer sea water if afloat.

[Neven]

Big PIPS arrows forecast for tomorrow:

[Patrice Pustavrh]

CT area dropped again and is now below 2008 for this day.
Data for 2008.6740: -1.5772314 3.1783452 4.7555766
Data for 2010.6740: -1.6041313 3.1619341 4.7660656

[Neven]

Indeed, Patrice. Compactness reached a new low as well: 60.92%. Just 0.05%, but every little bit counts. IJIS still has to revise though.

[Patrice Pustavrh]

Neven, be aware that AREA/Extent ratio cannot go below some value. Theoretical minimum is at 0.15 for given source (while comparing IJIS to CT data, this may not be true, if signal processing is not done in same way). However, we must take into account that we still have quite decent area covered with nearly 100 %. This area decline may indicate some more extent losses in following days.
If I may share some more observation, note that giant appearances and disappearnce of ice in some areas actually do not mean that that ice has melted away in single day. As I was informed on Ouslands blog, there is still some ice south of Wrangel island and AMSR images showed no ice. But if we know that extent is put on 15% threshold and that probably colors of concentration are put in this way too, this is very possible when having low concentrations of ice which we are observing now.
My rough guess would be, that there is about 2.5 mio km2 of more or less packed (90 % concentration) and another 2.7 km2 at about average 35% concetration (must admit, didn't do the actual counting, so please correct me if you find better values, it is just my view what might be going up there). This low concentration ice can put substantial difference in extent measure (and I think DMI graph will show some more decreases).
Why I am pointing this out. In my opinion, the argument from some Arctic warming denialist, that 30% area being above 2009 means recovery is not correct. The whole picture must be taken. Seing this, I see no recovery from 2009. I think that most, if not all measures of ice amount will show lower values than those of 2009. But the main question is, how low can ice measures go ?

[cynicus]

Werther, I completely agree.

Furthermore I think the TU Delft created -unintentionally, I'm sure- a small media hype by using that sensational headline. They should've made it clearer that their remarkable claim of "Halving the icesheet mass loss" depended on Grace measurements AND two specific publications (Velicogna 2009 and Chen 2009).

Without those two prerequisites the claims would be much less spectacular because the result largely agree with IPCC AR4 findings, other methods of measuring icesheet mass loss and even other publications that interpret Grace data.

An extensive summary of the research findings is described here: http://polarmet.osu.edu/PolarMet/PMGFulldocs/bromwich_nicolas_ngeo_2010.pdf
TU Delft press release (Dutch only unfortunately): http://www.tudelft.nl/live/pagina.jsp?id=7a6c3d15-1c1e-4869-b378-840a000c6803&lang=nl
The relevant section in the IPCC AR4 report is here: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch4s4-6-2-2.html
NASA also has some relevant input and numbers to share: http://earthobservatory.nasa.gov/Features/Greenland/greenland5.php

All in all a "storm in a glass of water" as we like to say in the Netherlands.

[Nick Barnes]

For more on the North Hole, see this false-colour from yesterday:
http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r04c04.2010246.terra.367.1km
or this one:
http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c04.2010246.terra.367
It's pretty clear that the very broken, 50% concentration? area runs right to the pole, and includes more or less the entire "eastern" Arctic Ocean (i.e. all E longitudes).

[Neven]

How much area or extent could we be talking about, Nick (or anyone)? 100K?

[Artful Dodger]

Larry: What happens to the goodness of fit for your 3 hypotheses if you normalize minimum SIE with 'compactness'?

[fredt34]

Unless I'm blind, NSIDC Ice Extent graph seems to have reached the 5M line on the Sept 4 graph. I just put a sheet of paper on the lcd screen, but it seems to be on the line.

Remember, as NSIDC order the years by "average sea-ice extent for september month", we'll have to wait (again) until October to get September's rank. Last year it was released on October 6.

(I'm just thinking that this "september average" method to compute the minimum will be inaccurate if the minimum extent happens, say, on October 5, with a rapide increase afterwards. Wouldn't some mobile average prove better ?)

And: have you already seen this tool and played with it, guys ??? http://nsidc.org/cgi-bin/bist/bist.pl?config=seaice_extent_trends is brand new for me!

[Artful Dodger]

Neven: In the absence of data, the best estimate for the Sea Ice Area in the N. Pole 'data hole' is the area of the hole times the 'compactness' ratio. So an estimate is 300,000 km^2 * 0.60 = 180,000 km^2 Sea Ice in the data hole.

Note that reporting websites assume 100% compactness for the data hole, and are therefore overestimating total Arctic Sea Ice Area, in our example by 120,000 km^2.

[Neven]

Lodger, I went ahead and did a blog post on the North Hole. My method is a bit crude to say the least, and I really hope I'm not inadvertently embarrassing myself too much.

I need some help there in further assessing how much extent and area are being overestimated, so everyone feel free to give tips, or even better, do the work yourself. :-)

[Steve Bloom]

Re ice sheet mass loss, it's key to bear in mind the trend rather than absolute numbers since under any calculation the latter are still quite small. The sharply rising trend shown by all analyses is a harbinger of much bigger things to come.

[Steve Bloom]

Thanks for the sat photo guidance, Dodger. I'll have a look later.

Charles, I looked at the DMI SST graphic and while that's some impressively warm water north of the Bering Strait, it still seems to be some distance from the ice edge. Over on the other side near Svalbard I notice some other ~50C water in contact with the ice, but what effect can we say we're getting there?

[JackTaylor]

You have a good eye with a straight piece of paper
@ fredt34 | September 05, 2010 at 23:42

Remember some averaging is involved and IARC-JAXA-IJIS numbers are used also
IARC-JAXA Sea Ice Extent 09,04,2010 = 5,192,188
http://www.ijis.iarc.uaf.edu/seaice/extent/plot.csv

But from your tip captured the NSIDC graph cropped a section, drew intersecting lines,
with an inset at 2X magnification at
http://www.polk-nc.com/agw/nsidc100904.png

200K out of 5,000K is only about a four percent ( 4% ) difference, not unusual.

[Phil263]

Preliminary report from JAXA-IJIS was SIE 5,142,813 ( decrease of 49,375).

[Gas Glo]

Updated report is 5,136,094. The 3 day average extent reduction is now 56,042 per day. The previous record for 3 day average extent reduction in or partly in or after September was 55260 per day for 3 days ending 2 Sept 2008.

[Gas Glo]

Do assume a fair bit of cherrypicking in that last post to pick on the 3 day average because we have had 3 days of significant extent reduction for the time of year.

[Steve Bloom]

Eyeballing the Bremen graphic, the reduction in the Beaufort region seems impressive. Could we yet see the same thing happen in the similarly mushy-appearing ice on the other side of the Arctic?

Gas Glo, this time of year that four-day difference is a big deal, i.e. the current reduction is even more impressive.

Is <5 million now a dead certainty?

[Neven]

Nothing in the Arctic is a dead certainty. :-p

[Steve Bloom]

The ice is on the move. Lots of long arrows on PIPS, looking like strong compression and flushing for tomorrow. I haven't been looking every day, but today's prediction seems to show a much more consistent flow, including (for the first time I can recall) big arrows in the Fram Strait proper. On many previous days I recall seeing big arrows leading up to the Strait, but then small arrows in it. Does this mean a big extent reduction number for tomorrow?

[Steve Bloom]

"Nothing in the Arctic is a dead certainty." I'm picturing you saying that in a bad Spanish accent while dressed up as a cardinal. :)

[Artful Dodger]

Steve, Climatology indicates a further loss in extent from today to Sep 14 of ~85 K, giving a minimum SIE of 5.05 M km^2.

However, 2010 is outperforming Climatology. We have 78 K less extent over the last 15 days than predicted by Climatology (avg about 5.2 K / day additional loss), so we may lose another 85+47=132 K over the next 9 days. This brings us to within 'slosh' distance of 5.00 M km^2 on Sep 14.

Any loss after Sep 14 will be all the rabbit and pork. Enough to get the Chattering Classes to sit up and take notice. And with this year's thin ice and warm water, it could be a late end indeed to the Summer melt.

Here's an interesting Climate Factoid: The all-time low CT Sea Ice Area Anomaly of -2.634 M km^2 occurred on Oct 19 2007. How's that for a late start to Freeze-up? Lot's of time for Ice Advection, wot?

[Peter Ellis]

Upward revision today, so I'll be daring and predict another 50+ melt tomorrow. That would really set the scene for a sub 5 million minimum

[Peter Ellis]

Upward revision of melt, that is - downward revision of actual extent.

[L. Hamilton]

5 million was my eyeball estimate of NSIDC, obtained less rigorously than Jack's method, but mentioned in my somewhat confusing posts upthread. Looks like NSIDC is below that today.

Probably with no gain in clarity, I drew a graph to show what I meant about this <5 million current NSIDC value being already closer to the pessimistic steepening-curve prediction (4.78), compared with merely-steady-decline prediction (5.37):

http://img.photobucket.com/albums/v224/Chiloe/Climate/predicted_extent0.png

[Kevin McKinney]

Fascinating and very substantive discussion, as usual--much appreciated.

As I've been updating this blog on the progress of Oliver & Lancashire, I'd be remiss not to report that they've completed their trip at Resolute as of Sept. 3. Their 17-foot Norseman was sailed and rowed for over 2,000 miles of the Canadian Arctic, over two seasons; she'll now be auctioned off to benefit their charity, Toe In The Water, which benefits wounded UK war veterans.

[Kevin McKinney]

Prelim for the 6th comes in at -40K. Gangbusters for this time of year.

[Jon Torrance]

Keven,

Indeed. Consider the last few days and how they rank compared to the same dates in other years in the JAXA record:

September 3 - 1st
September 4 - 2nd
September 5 - 1st
September 6 - 1st unless there's an upwards adjustment of more than 2500 coming

Quite a spurt, putting the loss in September so far first at 233,281 not far ahead of 2008. The range runs from there down to 2005, which actually gained 17,500 in extent through the 6th. And yet, 2005 is the year with by far the largest loss in extent remaining after that date. It's kind of awesome that that's possible.

[Steve Bloom]

Out of curiosity, could anyone who's been following PIPS comment on how unusual the current displacement graph is? Thanks.

[Artful Dodger]

The PIPS history is all online, Steve. Go have a look and report back. Cheers!

[Steve Bloom]

I knew that, Dodger. I'm not going to go to that considerable trouble. If nobody here has been looking at it consistently enough to have an impression, that's fine.

[Neven]

Steve, I've compared 2007, 2008 and 2009 in End Zone 2; ice displacement.
Although 2007's ice displacement arrows generally point in the same direction (especially towards minimum extent) they are not as big as they have been in the past week.

I'll have a look at 2005, which I unfairly do not consider in these SIE updates. As Jon Torrance says, it made quite a spurt after this date.

[Neven]

I'm picturing you saying that in a bad Spanish accent while dressed up as a cardinal

The bad Spanish accent is spot on! But I'm wearing a cowboy hat.

* music from Once Upon a Time in the West *

'Nothing in the Arctic is a dead certainty.'

[Steve Bloom]

The hat and horsey are OK as long as I can be Cardinal Biggles.

Re the displacement, I recalled that comparison but was wondering about any time during the year (or maybe just the melt season). That's why the task of looking seemed rather large. OTOH, what about the periods of maximum dipole anomaly? Where I'm headed with this is that I suspect the current pattern may be unique, and a function of the anomaly plus the condition of the ice. If I'm right, the ice would have been too sticky in prior years to show such a pattern. Of course this is all speculation.

[Neven]

If I'm right, the ice would have been too sticky in prior years to show such a pattern. Of course this is all speculation.

Steve, I think I agree with you that there seems to be a shift this year in the way (a large part of) the ice pack behaves.

But look at the PIPS ice displacement forecast for September 12th 2005:

Now that's what I call big arrows!

[Gas Glo]

2005 had big arrows and a late surge in extent reduction. Does that mean that is good for late extent reduction again this year.

ADwrote
"The all-time low CT Sea Ice Area Anomaly of -2.634 M km^2 occurred on Oct 19 2007. How's that for a late start to Freeze-up? Lot's of time for Ice Advection, wot?"

I am sure you know that you could have an early but slow start to freeze up and get an anomaly record sometime later.

To add to the pedantic notes: There is always the same amount of time for ice advection 365/24 but it depends on weather and amount of ice heading for the exits. The race to fram straight may indicate that there was less ice than usual in the right areas until recently?

L Hamilton, that curvilinear graph show an upward trend prior to about 81/82. I doubt the trend was really upward then. If you restrict that to a slow decline, I assume the best fit is then not as fast a decline at the end (and 5m this year would be even nearer the curvilinear fit rather than the straight fit)?

[Neven]

Tomorrow's ice displacement forecast still showing arrows pointed in the same direction:

[Gas Glo]

Steve,

I haven't followed PIPS much at all but I thought 12 Aug was quite similar
http://www7320.nrlssc.navy.mil/pips2/archive/retrievepic.html?filetype=Displacement&year=2010&month=8&day=12

That doesn't seem to be far back to find something similar but maybe you want to exclude 2010?

[Voyageur]

Off topic but for the lurkers among us who learn much here, I curious as to your views on the Delft study published yesterday http://www.tudelft.nl/live/pagina.jsp?id=7a6c3d15-1c1e-4869-b378-840a000c6803&lang=en ... which strikes me as interesting as much because it underscores just how little is known and how widely estimates vary as anything else

[cynicus]

Voyageur, please look a bit further up in this thread:
- http://neven1.typepad.com/blog/2010/09/sea-ice-extent-update-28-riding-the-seesaw.html?cid=6a0133f03a1e37970b013486f05042970c#comment-6a0133f03a1e37970b013486f05042970c

and:
- http://neven1.typepad.com/blog/2010/09/sea-ice-extent-update-28-riding-the-seesaw.html?cid=6a0133f03a1e37970b0133f3d17126970b#comment-6a0133f03a1e37970b0133f3d17126970b

The research fine-tunes the Grace satellite data interpretations, but Grace isn't the only data source for icecap mass balances. So, a lot is already known and a lot isn't, but science advances steadily.

[Neven]

Bedankt, cynicus. :-)

CT area dropped 47,909 square km. Anomaly is now -1.599 million square km. Compactness went back down to 61.75%, but this will change once IJIS revises.

[Peter Ellis]

Another upward revision of today's melt - this doesn't look like it's slowing down any time soon. Under 5m by the end of the week?

[Neven]

Indeed, Peter. According to my spreadsheet, whichever track of the previous 5 years 2010 prefers to follow, it will end up below 5 million.

But in the Arctic nothing is a dead certainty.

* whistles tune from The Good, the Bad and the Ugly.

[dorlomin]

http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/seaice.anomaly.antarctic.png

Remarkably the antarctic is back in negative teritory, if only just.

Interesting.

[L. Hamilton]

Gas Glo, you're right about my curve's unrealistic behavior in the early part. It's also, I think, unreal to predict a steep crash to zero extent; seems more likely that some remnant will prove persistent. For both reasons, an S-curve such as logistic or Gompertz makes more intuitive sense, but linear & quadratic are simple places to start.

To get slightly more realistic, my own preference is to shift to substantive statistical models, such as predicting September extent from July extent, July concentration, and the previous September's extent. That's what I sent off (what the heck) to SEARCH. Coincidentally, it yields pretty much the same September 2010 prediction as the simpler quadratic model. But, as I've said, this is all purely statistical, which means it has a better chance to be close "over the long run" but lots of uncertainty for one year:

http://img.photobucket.com/albums/v224/Chiloe/Climate/September_extent_predict4.png

[Christoffer Ladstein]

Smell of 2008 is in the air! With the weatherforecast posted earlier by Neven, if the persistence of that regime last just for a couple more days, the vulnerable less compact ice of 2010 just HAVE to be compacted to such a degree that we ought to see a SIA VERY close to 2008. Less than 300 k to go!

[Artful Dodger]

Gas Glo / Larry: I wonder if a logistic or S-curve is the best model to describe the underlying physics of the Arctic Sea Ice pack? Maslowski expects "In the end, it will just melt away quite suddenly" (credit: fredt34 July 3 2010). So no long tail in the Ice / time curve.

In some ways, the loss of Sea Ice is similar to the discharge of a Battery, with Voltage similar to Area (Extent is deprecated), Energy like the remaining Ice Mass, and variable Load (charge/discharge cycles) being like the various Climate forcings and WX variability. Below is a sample discharge curve for a Lithium-Ion battery. It's rate of discharge depends on temperature and load, but the shape of the curve is consistent.

After Sep 15, 2010 we can use PIOMAS estimates of Ice volume / Average to estimate current "Capacity Percentage" of our Arctic Sea Ice Battery. This will show which part of the curve we're on, and then we'll have an new, intuitive sense of how much time is left until the last of the Summer Sea Ice is gone.

Of course, different battery chemistries have differently shaped discharge curves, but are generally similar. I imagine the enthalpy of heat for sea ice at varying salinity (proxy: age) would be the appropriate parameter to model.

[Jon Torrance]

PIOMAS now updated to August 31st with very little change since the middle of August - http://psc.apl.washington.edu/ArcticSeaiceVolume/IceVolume.php.

[Jon Torrance]

To be clear, little change in the size of the anomaly. Obviously, that means the actual volume has decreased significantly since then since the daily average over their 1979-2009 baseline period hits its minimum value sometime in early September.

[Gas Glo]

I was also wondering about S curves and logistic curves assuming too much about the end slope/tail being similar to the beginning. I was thinking that using the way the 5 year ice disappears may be a more appropriate signal to watch and implement for the shape of the end tail.

Of course, models are an alternative and if they are doing better than this fit suggestion then they should be preferred. Just a thought and another reason to want the age analysis to be done in km^2 and made available (rather than just as % on a graph without clarity of % of what). This may be available somewhere I haven't seen so do tell me if you know where.

[Neven]

Thanks, Jon. Fixed your link.

BTW, what's funny, and I think I had this last time too, is that I'm not seeing the updated volume anomaly image yet?

[Jon Torrance]

Thanks, Neven.

Looks like they don't get around to updating the small version on that page until sometime after they post the high-res version. Or is neither of them updated for you?

[Neven]

Let me try again. Nope, neither. Large image is 08-16 for me. Weird, eh?

[Jon Torrance]

Mirror server handling European traffic not yet synchronised with North American server?

[Neven]

Ah, I restarted FireFox and that seemed to do the trick. Either that, or they just synchronized the servers. ;-)

[Gas Glo]

FWIW I'm in UK and I saw the updated version before posting my earlier comment at 23:54. (using ie)

[Artful Dodger]

GasGlo: Totally agree. Sea ice age is an important proxy for salinity, which is extremely important for insitu melt. However, most old ice doesn't melt in the Arctic. Most is advected out of Fram Strait and melts in the Atlantic. So sea ice mobility is an even more important proxy for lost of the oldest ice.

Neven: PIOMAS anomaly thumbnail has been updated. You're probably seeing the image from your Browser's cache. With Firefox, hold down the 'Shift' key and click 'Reload' to force a Cache refresh from the source file online.

[Neven]

Good tip, thanks! Naughty Firefox!

So it's not a coincidence that 'cache' means 'hide' in French.

[Artful Dodger]

Yeah, you cache that thumbnail the 1st time in each Firefox session when you view your 'Arctic Sea Ice Graphs' page. But unless you follow the link, the large image will be dropped from cache, since it may be weeks between views.

[Artful Dodger]

Anju: Here's your Average Sea Ice thickness Estimate for Aug 31, 2010:

PIOMAS-anomaly:  -9.450 * 1000 km^3
PIOMAS-avgVol:   13.525 * 1000 km^3
PIOMAS-volume:    4.075 * 1000 km^3
IJIS Area Aug31:  4.092 M km^2
Avg thickness:    1.004 m

[Evilreductionist.blogspot.com]

Big drop again today in JAXA - close to 60,000. It is not so much a sea saw as a straight drop on the slippery slide.

[Kevin McKinney]

Yes, indeed. I suppose it's those 'big arrows' at work, primarily, followed by bottom melt. I look forward to seeing the CT map again tomorrow.

[Kevin McKinney]

A quick note following a glance at the Nunavut weather: the extent may be off the seesaw for the moment, but the seesaw of the seasonal cycle is clearly tipping back as the year wanes.

There's still a lot of temps well above climatology, but above climatology no longer means above freezing, necessarily. And most of the southern Archipelago is now experiencing around 8 hours of darkness daily. Soon enough the sun will set for the long night.

My gut feeling for quite a while now has been that we'd likely see minimum around the 24th, as was the case in 2007. We'll soon see if that's correct. If so, surely we'll see a minimum below 5 million. But though we've been joking about how "Nothing in the Arctic is a dead certainty," I do think that's actually a word of wisdom. But how many surprises can there be left?

[Greg Wellman]

Comparing the Jaxa extent graph with the Jaxa area graph, the last few days of extent reduction have been more compaction than melt ... of course the stage for that was set by some of the lowest concentrations ever. If the displacement arrows continue to favor compaction, the extent could bottom out nearer 2008 than we thought. Certainly the area is looking much like 2008.

[Artful Dodger]

Greg: the 'compactness' ratio CAPIE (CT Area Per IJIS Extent) is going down, so what we are seeing now is actual Melt, not compaction. Not surprising as warm water meets diffuse sea ice.

Here is CAPIE for the last 10 days: (CT's data is released a day behind)
64.66% Aug 27, 2010
62.66% Aug 28, 2010
61.98% Aug 29, 2010
62.12% Aug 30, 2010
61.00% Aug 31, 2010
60.84% Sep 01, 2010
60.33% Sep 02, 2010
60.28% Sep 03, 2010
60.90% Sep 04, 2010
60.61% Sep 05, 2010

[Anu]

@ Artful Dodger | September 08, 2010 at 01:52
Thanks AD - was going to do the calculation myself late tonight, but you saved me some precious time.

When I did a quick calculation for the 8/16 anomaly weeks ago, I got 1.04 meter average thickness.
I think the thin margin ice is still melting away slowly, leaving the thicker, remaining ice - which is also melting a bit on top and bottom.

Note that the Polar Science Center says that September Ice Volume was lowest in 2009 at 5,800 km^3 or 67% below its 1979 maximum.
http://psc.apl.washington.edu/ArcticSeaiceVolume/IceVolume.php

Looks like we will have a new winner for September average this year even if the melt season doesn't go another week or so - which it probably will.

Dr. Maslowski has been saying for years that it's all about the volume decline...

[Greg Wellman]

Lodger, I'd noticed that about the CAPIE, but I'm a little dubious about calculations from two different sources with different methodologies. IJIS has an area graph that's falling much slower than the extent is falling, so from just the one source there's an implication of compaction. I agree that the CT area is in free fall and likely to drop below 2008 momentarily if it hasn't yet. And definitely any ice that floats past the west side of Spitsbergen is immediately melted by that warm pool there. I suppose another approach to getting the average concentration from a single source would be to "integrate over pixels" on the Uni Bremen map.

[Artful Dodger]

Geez, that means we've already lost 31% of the Sea Ice volume remaining in Sep 2009 (4000 left out of 5800). So could that possible mean only 2 years of Sea Ice left at this pace? I don't know off hand of anyone calling for a total melt out by 2012... anyone?

[Neven]

I don't know off hand of anyone calling for a total melt out by 2012... anyone?

Al Gore? :-p

You'd have the pseudo-skeptics about that one. They are keeping score.

BTW, CAPIE, good acronym.

It is not so much a sea saw as a straight drop on the slippery slide.

Hey, you guessed the title of my next SIE update!

[L. Hamilton]

A few years back at an NSF workshop, a small group of us pondered what one annual cycle in the Arctic might look like, 50 years hence. Gavin Schmidt led the speculation, based on some things we know -- like it will still get cold and dark each winter, so ice will form then. Would *all* of that melt every summer? Seems unlikely, even if most of it does.

I think that argues for an "average" September curve that could be steepening now but in later stages slow down, somewhere short of zero. A Gompertz curve (asymmetrical S) might fit that bill, but like all these other functions it's just a smooth guess.

[toby]

~59,000 gone last night, though there may be a correction to that! If this continues, extent will drop below the 5 million km^2 mark tonight. And it looks like it will.

UofB chart of the rate of decline shows it upping slightly. My own "personal" prediction of 5.1 is well shot :))

[FrankD]

Jon, Dodger, Anu - I was going to say that...stupid time difference...>:-(
Seriously - good points. If the extent drops much more in the next couple of weeks, we'll be looking volume dropping to perhaps 3700 sq kms, which is just scary.

"I don't know off hand of anyone calling for a total melt out by 2012... anyone?"
2012? Maybe Charles Wilson (the low outlier in the SEARCH predictions).
2013? Definitely - Wieslaw Maslowski made the call nearly three years ago (December 2007 - but his data set only ran to 2004), and when ice extent rose in 2008 became an object of derision by the denialati.

Our projection of 2013 for the removal of ice in summer is not accounting for the last two minima, in 2005 and 2007," the researcher from the Naval Postgraduate School, Monterey, California, explained to the BBC. "So given that fact, you can argue that may be our projection of 2013 is already too conservative."
http://news.bbc.co.uk/2/hi/7139797.stm

Yes, I'm begining to think it might have been too conservative...especially given that this year we've been lucky with the weather. Bad weather could have cost another 5 or 600 km^3, and we'd be talking about nearly 50%, not a little over 30.

[Artful Dodger]

Frank: Time is the fire in which we burn ;^) ... It is Human nature to 'turtle' when attacked, which is the strategy behind all the pseudo-skeptic shouting. And it's the motivation for the break-in and theft of email from U. East Anglia (they got the Directory suspended). Suspicious timing for the public release, a month before Copenhagen, wot?

If we do see a complete loss of Arctic Sea Ice by Sep or Oct of 2012, it could be just in time for the next U.S. Presidential Election. With a growth spurt of courage, Obama could seize the High Ground on Climate Change policy, and get a new mandate from the people to force Congress to deal with a price on Carbon.

Could the rest of us be this lucky?

[Neven]

Could the rest of us be this lucky?

That depends if Obama is just a puppet or not. Anyway, as long as there is no discussion on whether the concept of unending economic growth is rational and humane, we can forget about real solutions. And somehow I don't think Obama will be spurring that debate. But more on that later.

[Lord Soth]

L. Hamilton

Somewhere I read a paper that suggests that their will be a sudden climate shift in the arctic when most of the ice is gone. Arctic winters will be 4-6 degrees C warmer. Winters will still be cold and ice will form, but it will be insulated by a snow blanket and have less time to form. Spring in the arctic will come earlier, and fall latter. My guess is that ice free summers will come by Mid July, once we reach the ice free summer state.

If there is a slow down at the end, the tail of the curve will only be a few years long, to allow the remaining thick ice against Greenland and the Archipelago to be pushed out or melted in situ.

[Neven]

PIPS is again forecasting some relatively big arrows tomorrow, all pointing towards Fram, so it should be possible for extent to go under 5 million square km:

[Neven]

CT sea ice area has dropped 37K, currently stands at 3.11 millions square km, which is 1.624 million square km below the 1979-2008 mean.

[Phil263]

Neven

And somehow I don't think Obama will be spurring that debate. But more on that later.

I wouldn't underestimate Obama's courage. So far, he has shown remarkable tenacity in pushing through his agenda. I think on the economic front, he still "has to see the light" but I am still hopeful... Better than our own Australian Labor government who reneged on its 2007 election platform to get serious about climate change. The Labor government just managed to survive this election thanks to the support of independents and the Greens , but we're still a long way from having a carbon tax or even carbon pricing down here!

[FrankD]

I notice that CT's Regional Area graphs show the Arctic Basin dropping below 2.5 M sq kms today. Does anyone know what it got down to in 2007 - I'm assuming lower, but Im curious as to how much.

Re: politics, all I can say is that in this risk-averse, spin and platitude heavy times, politicians no longer lead but follow their electorates. It will take leadership from the American people to achieve anything in the US - only when they ask "can you do something about this, please" will Obama say "Yes we can" again. And if the other side get in, no one will be asking that particular question.

I don't think Obama is a puppet, as such, its just that he, like every other public office holder, is beholden to vested interests.

[Artful Dodger]

Frank, all the Basins melted out in '07 except the Cdn Archipelago and the Greenland Sea, with this last stuffed with Ice advected thru Fram Strait. Here's a picture. So as a first approximation, ALL of it in the Central Basin.

[FrankD]

Cheers Lodger,

That would suggest that we're pretty close to 2007's Arctic Basin area (probably still above, but not by much). The worry as I see it is that the Beaufort or the Kara can melt and freeze but the the Arctic Basin is the "core" - not just most of the ice, but mostly the thickest, most compacted...you know, "best". Wellum, until Neven's pole hole came along...

I see it as kind of like those nature reserves that are disturbed at the fringes, but those fringes protect a core of pristine ecosystem. Any losses in the core are more serious than losses at the fringe (qualitatively, quite apart from the numbers). But with the "defences" down to almost entirely single year ice which (as we saw this year) can get nixed by the end of June, we will see more and more "serious" losses to the core.

Nothing to novel there - same old multi-year ice riff. Just thinking aloud.

BTW - further to your question about 2012 predictions:There was a lot of discussion on this in late 2007 with a few numbers being chucked aroung. I'm not sure if anyone actually tipped complete melt out by 2012, but there was some money laid on some big drops. See here + the links to other blogs:
http://scienceblogs.com/stoat/2007/12/betting_on_sea_ice_following_t.php

The big bet then was between William Connelly, Joe Romm and others on whether extent would drop below 10% of the 1979-2000 average minimum - which I think was 6.75 - 7 million (NSIDC) - at any time between 2007 and 2020 (ie extent lower than ~700,000 sq kms). If I read it right, NSIDC tracks slightly (a few percent) lower than JAXA.

'Course, back then every one was talking extent, but those volume numbers point to a wrinkle they might have missed. We could see volume drop 30% per year (ie more of the same of what we saw this year) for another couple of years with little extent drop, and then suddenly plunge millions of sq kms in a single season when all that wafer thin ice finally melts. Not saying it will happen, just that its a possibility.

Oh, and of course, the Mayans picked 2012 as well ... ;-)

[Neven]

Another big revision downwards (7K), final decrease number: -66,093 square km.

But there are clouds on the horizon...

[toby]

"... clouds on the horizon". Very tantalizing, Neven, do tell.