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I would call it a recovery, if the measured area had a thickness of at least 2m and far less cracks and leads. Even the HYCOM/PIPS model estimates half of the basin below 2m.



I believe it is hard to make predictions on the state of the ice for a particular year (max or min_), just as hard as it is to tell how cold or mild the next winter is going to be. I also think (and this is just intuitive ) that to make predictions in the medium term is also hazardous. Over the last decade, we have seen a sharp decrease in polar ice, but the next few years might see a temporary upwards swing. Of course this wouldn't mean that the long trend is not down, but sure enough some will talk about "recovery". After a decade of seemingly unbreakable droughts in SE Australia, we just had two wet years. Now farmers seemed to have forgotten about losing a crop and city dwellers behave as if water restrictions are a thing of the past. Of course, we've just had a double La Nina but people have short memories.
I think we need to see 40 or 50 years before we can have a clear idea about the trend of climate change and even that might not be enough.
It is tempting to make short term forecasts (and i am first one to be tempted) but really as you say it is just a gamble. But just to show you that i am as bad as anyone else, my prediction for 2012 is that the SIA min will be over 3.5 Million :-)

Account Deleted

The real sign of a recovery would be having a +900K different at day 240-270. As I suspect that this "recovery" will just lead to a series of century breaks early in the melt season.
Neven - maybe your next poll should be to guess when the first century break occurs.


Calling it when we are only 42k below the peak? Well the forecasts certainly look like there should be area reductions so you are probably right.

Kevin McKinney

What the hell is "Pétanque?" Never mind, I'll Google it.

My prediction was horrible, too--I think I went for something like 12.85 K, which makes your miss, Neven, seem quite close.

The only saving grace was that I called the time of the maximum for March 17, which was at least sort of close.

Undeterred, I'll make another WAG--I don't think the sea ice will have a very good year this year. I won't do numbers (I'm chastened to that extent), but will just say that I think this year's minimum will be close to last year's. Why? The late surge is fragile ice, and I think we may get another good dose of advected heat from the Pacific once again.

But as always--we'll see.

Account Deleted

The graph above suggests that 2012 is a bit of a rerun of 2010.

Bob Wallace

Difference from 2010 is, I think, is that a bunch of the ice is well on the outer-Pacific side where melting tends to occur early in the year.

The Bering melted by the end of May last year. The Okhotsk ice was largely gone by then.

This year the Atlantic side ice looks weak. The overall extra extent/area is largely due to a thin skim of ice on the Atlantic side.

There could be a record amount of open water within the first month of melt. Lots of water available to absorb heat and permit wave action for longer than usual.

Then there's lots of opportunity for transport out with the fixed ice on the north side of Svalbard missing. And lots of opportunity for warm Atlantic water to flow in.

If heat does come in from the Pacific to attack the Pacific side of the Basin then we could see a new record.

On the other hand, something else could happen. In the last ~30 years of volume measurement the graph went up about 1/3rd of the time.



When I got home from work tonight, I made gin and tonics for myself and She who must be obeyed. I put a cube of ice in mine, and the same amount of crushed ice in SWMBO's.

The ice in SWMBO's drink covered the whole surface of her drink, while mine just had the cube bobbing in the middle. Yet oddly enough, a couple of minutes later, her drink had no ice left, while my drink still had a (somewhat reduced) cube, bobbing in the middle.

Extent, schmextent I say...



Frank in that example, there is enough heat around but surface area is limited in one G&T. With arctic, is it the opposite with limited heat availability and plenty of surface area and time to adjust the level of ice?



I concur on the sea ice maximum, given the shifts in AO towards neutral. This matches better with my assumptions from the 15th. The strong lows in the Atlantic south of Greenland and in the Bering may limit further ice development/growth.

It will be interesting to see how fast an SIA decline we experience in the next 60 days.

Aaron Lewis

Is "snow" sitting on the surface, "sea ice"?

"Easy come, easy go!"



There's quite a lot of cracking occurring in the Chukchi Sea at the moment. Suppose, just for the sake of the argument, that a lot of that gets flushed out into the Bering Sea, and is replaced by a skin of grease ice, and some flowing in from the central area.

That will do splendid things for the Extent metric, but do you think it represents an improvement in the health of the ice-cap generally?

If, as appears to be the case, the average thickness of the pack is at a record minimum, then increasing extent numbers don't really mean anything much. Or nothing positive, at least - greater surface area does allow a more rapid heat exchange with the ocean of course.

Lord Soth

Well you can't blame the sea ice rise, on the east coast of North America.

Setting here in Halifax Nova Scotia, it hit 27.2 celsius, and this is a province that surrounded on three sides by sea water at 0 celsius in March, and never far from the ocean. Not bad when our average high is 4 celsius for this date.

I realize that you sometimes get once in a five hundred year events. But when they occur in March in 1998, 2010, and three days in a row in 2012 in Nova Scotia, I get a little nervous.

In fact we broke the all time April high here in halifax; just three days into spring.

And it's not just us, it's the whole north eastern North America.



Frank, I agree with you it wouldn't be good for health of ice pack. In fact over at the stoat I recently wrote
">"Why is volume better?"

Volume is largely a measure of the heat budget. Extent can be high with thin ice that will rapidly disappear."

I'm just not sure your analogy is an appropriate one, but am willing to be persuaded otherwise.


I'm not taking the time to do any sort of analysis on this, but this late max appears to be part of a trend toward low late-winter/early-melt-season anomalies. Looking at the CT "tale of the tape", there appears to be a seasonal (and usually annual) maximum on the anomaly line around March or April since 2005.

My guess is that it's thinner ice being spread out more before melt and real fragmentation kick in. Any other ideas?

Calling it when we are only 42k below the peak? Well the forecasts certainly look like there should be area reductions so you are probably right.

I'm starting to get used to being wrong, but an even higher and later maximum, and I'm shutting down the blog. ;-)


Neven wrote:

and I'm shutting down the blog

Fortunately nature came a bit to the help:

New Found Land coasts have almost positive temperatures now. Baffin Bay is up too, -2 °C at Nuuk and -7 °C at Illusisat. At Greenland's East coast south of Iceland temperatures are positive too, even a stagering 5 °C at Tasiilaq.

In Alaska, it's still pretty cold, but at last the temperature has gone up somewhat: -27 °C at Barrow, -16 °C at Wales (Tin City), -4 °C at Anchorage, -6 °C at Fairbanks.

Thus it looks like thee blog would survive after all. :-)


Hi Neven,

In a last-ditch effort to save the blog, I'd better quickly predict the absolute certainty of a higher and later maximum.

There. That should do it. I am invariably wrong ;}


Shortfatape wrote:

My guess is that it's thinner ice being spread out more before melt and real fragmentation kick in

No, it's not like that I'm afraid.

This year in early March a cold spell invaded New Found Land and Baffin Bay as well as the Bering- and Okhotsk seas. Temperatures over night -30 °C and lower for all of these regions. Temperatures -11 °C @ -15 °C lower than the average, which was quite appalling a situation btw. And in these conditions the ice field does simply what it has to do: it develops it's thickness and expands itself in an unlimited way.

In March/April 2010 we saw exactly the same phenomenum in the very same regions. Something in vain I tried to call everbody's attention to early this month.

Remember, "Non cantare vittoria troppo presto!", which not literally but properly translated in plain American English means: "Don't jump to conclusions". :-)

Chris Biscan

Jaxa shows reductions in the Kara/Barents, Bering big time, and Baffin.

the max has been reached.

Dominik Lenné

Looking at the last five years (07, 08,09,10 and 11 that is), it appears that volume anomaly has a downward flank that starts somewhere in the spring and ends in late summer. If this is not purely statistical, it would mean, that volume anomaly drop in those last years is not so much driven by slower freezing, but by faster melting. This could pretty much be the onset of one or more feedback processes. In a simple model, melting rate is more or less linearly dependent on air temperature, plus irradiation of course, but not much on ice thickness, because the heat flow is used up in the melting layer. Any feedback, in which the thinness contributes to accelerating volume drop, would go over the area: thin ice opens up faster at the edges, leaves ocean water to be both warmed and pushed by the wind to melt from the bottom. Also, wind might cause turbulence and desturb the thermo-/halocline. The heat in deeper waters would be more than enough to melt all the ice.

Janne Tuukkanen

Wait a second. Nova Scotia +27 C, Newfoundland -15 C? Is that some deep temp gradient, or what!


Morning Janne
Mind that Newfoundland is not just the island NE of Nova Scotia, but stretches up to 1600 km north to Cape Chidley. For St John's on the island there's no higher max the 22nd march than about 10 dC.
BTW found a second field of punctuations on fast ice, 900 km east of the Laptev Sea, near Ostrov Khrestovskiy.
Researching these marks, I couldn't find a thing on MODIS 2011.
So why now? Is it lack of snow cover? Or is it related to Semiletov's report of 'fountains of methane'. Could it be enhanced sub-surface permafrost melt through warm Atlantic influx/more insolation all through the last 12 months?


Dominik mentioned the possible onset of feedback processes.
I't seems hard to accept while weather is producing such high extent values at the moment. But Neven's +900K is SOO +200/Bering +450 and Baffin +250. FYI through cold from the lower troposphere, which doesn't penetrate deep into these seas. On the risk of at least having Neven shutting me down on this blog, I suppose the largest april downfall in extent since the beginning of the satellite era is about to start. Never mind my credibility...


I didn't put in an estimate as I thought I had missed the boat and it had already happened.

Pete Mason

"I'll try to be extra careful and conservative from now on."

-- I hope not!!

Keep up the good work.

L. Hamilton

Can you predict the min from the max? Not very well, simple trend lines appear to work better.

- Regressing mean September SIA on year (i.e., simple linear trend) yields an R^2 of .7358, about 74% of variance explained (and predicts 3.53 as the mean Sep area in 2012).

- Adding March SIA as a second predictor raises R^2 by a trivial amount, to .7377. The coefficient on March is not significant with or without AR(1) errors.

- And predicted Sep 2012 SIA (taking March area including this year to date, as well as the linear trend into account) is then 3.57.

L. Hamilton

Which reminds me, my naive nonlinear prediction for September mean SIA is 3.0, plus or minus 0.7. This from models estimated last October:



After being so far off on the Max - I was in the 13-13.2 group - I am humbled. The Bering and SOO extents went way beyond what I expected. On the Atlantic side, if we get early warm rain events on top of already thin ice ... It's difficult to predict minimums but if April melting sets a record then I expect a SIA minimum between 3.4 and 3.65 this September.



Wonderful set of graphs - as usual!!


Yes, that's a very nice graph, Larry.

Comparing UB SIC maps for the 24th and 23rd, it's obvious that the ice is retreating everywhere (SoO, Bering, Baffin, Lancaster, Greenland). We should be seeing some big drops very soon now.

L. Hamilton

"We should be seeing some big drops very soon now."

After days of little movement, DMI registered -145k from 3/23 to 3/24.

L. Hamilton

Regarding my 2012 predictions graph, it was done so long ago (early Oct 2011) that Uni Bremen was still in the chase; in fact it was my favorite dataset at the time. I had just waited for the NSIDC Sep numbers to come out before drawing it.


I don't think that the area or extend charts doesn't really say much about the current state of arctic sea ice. In my opinion much more can be seen from the ice thickness animations and charts.
If I compare the actual chart with 20110401 no old ice above 2m is left between siberia and the pole itself. When no spreading of the thick ice happens, we will see an icefree northpole in september.


In relation to the comments above:

The Russian MYI thickness charts show that we are almost at a point that MYI is no longer over the pole (90N). Note the difference between the 1 Nov 2011 chart:


And the 20 March 2012 chart:


The US Navy sea ice thickness map is showing a similar current state:


If the Russian observed drift continues we may have thinner ice over 90N and open water at sea ice minimum.

A shift toward negative AO may become more sustained through spring, and contribute to more rapid warming.

Today's temps (260312 0600) in south Greenland are perhaps a precursor of more warmth to come, depending on the low over it.


Articicelost80's link confirms weak ice conditions at the pole - see the Russian expedition 21 March comments:

"Some of the latest information about the state of ice at the North Pole."



MASIE has dropped nearly half a million km^2 in the last 2 days. I think the melt has begun!



"It's difficult to predict minimums but if April melting sets a record then I expect a SIA minimum between 3.4 and 3.65 this September."

Is that as measured by Cryosphere Today, or by a different group? I would have thought that a record April minimum would indicate a CT SIA minimum below 3.4.

The last CT SIA minimum above 3.4 was.. 2009 at 3.4246. In terms of April melt. 2009 went below 11 million sq km of CT SIA on day 143 (May 23rd), whereas 2006 and 2011 hold the record, breaking that barrier on day 134 (May 14th) [2007 was on day 138]. It will be interesting to see if 2012 pushes that date any earlier.

I'm highly sceptical of any thickness charts. There is such high spatial variability in the thickness that I'm not sure an assimilating model can be all that accurate. We just don't have observations that are sufficiently good. This is why extent and area are more important from a trend point of view - they're more reliable measures.


I don't know what to make of the ECMWF weather maps. It really looks like the freezing season is over, with some huge lows over Kara and Laptev in days to come (probaby halting and reversing the retreat south of Novaya Zemlya in the past few days). I'm under the impression that lows in those regions are typical for melting season weather.

Except for Baffin I don't see much difference between today's and yesterday's UB SIC maps. The weather I thought would have Okhotsk SIA drop like a rock, is already gone. That forecast didn't play out. Bering might lose some more in the next couple of days.

But other than that I don't know what to make of the weather maps. It's transition time, and that's the hardest time to make any sensible predictions (as I have proven beyond any doubt in the past two weeks).

Chris Reynolds

Hi Misfratz,

PIOMAS is well validated against observations during the period of submarine measurements from the Data Release Area and the ICESat missions.

If you download the Schweiger paper, it's large and daunting, but just check out the figures.

Figures 2b and 3b are scatter plots of modelled vs observed thickness. Figure 4 likewise but with fewer points, NPEO stands out as having poor agreement, the paper states no reason is known and this matter is being investigated.

Figures 5 and 6 show good agreement between ICESat and PIOMAS. However there is less agreement for the AIR EM data which is probably because PIOMAS underestimates the thickness of thick ice.

The problem at present is that we have very little publicly available observations of ice thickness. So it is reasonable to ask whether PIOMAS is telling us the real story about the thickness of the sea-ice. However this then begs the question - if PIOMAS was doing a good job back then why would it be failing now?



Arctic sea ice maximum marks beginning of melt season

On March 18, 2012, Arctic sea ice extent reached its annual maximum extent,


Thanks, crandles. Post is up.

Dominik Lenné

Concerning PIOMAS and its verification - it's now one and a half year that CryoSat 2 is spitting out terabytes of data and still no ice thickness map published except one in June 11. This is one thing I'm wondering about very much. (I think I did it some time ago on this blog, did I?) (rant)What is this satellite good for, I mean it's meant to produce thickness maps, isn't it? Instead they showed off sea level anomaly maps where you can see every bloody eddy of the gulf stream. (Probably grossly unjust.)(/rant)

Other question: does anybody here know of arctic air temperature maps, monthly mean over 10 yrs or so, just to satisfy some weird interest of mine.

Peter Ellis

Eh, I think it's important that we don't get unrealistic expectations of what Cryosat will provide. It cannot and never will provide real-time thickness data in the same manner as (say) the ice concentration data. It just doesn't have a wide enough field of view. In order to make the very precise altitude measurements that allow it to determine freeboard, it "sees" only a very thin line immediately under the satellite.

Freeboard measurements should start being released "soon" - the plan was to start around a year after the initial calibration. The first maps were released June last year, based on ~March data, so I guess we should see some freeboard data in the next couple of months.

BUT - and it's a big but - it will never be "pictures" like the Bremen or Cryosphere Today pictures of ice extent.

Here's an example: although freeboard (thickness) data isn't available yet, they are showing the ice concentration data. Here's the outputs of the last data batch.
That is from a WHOLE MONTH of orbits - and it's still not enough to cover the ocean even once over.

What it will do - and do very nicely - is give statistical indications of the distrubition of ice thicknesses in different Arctic regions, although you'll likely have to average over a month or so to have enough coverage to build a picture. But I think there's a very false idea on this blog and others as to what to expect from it.

Peter Ellis

"Distrubition" is too a real word. Honest.

But I think there's a very false idea on this blog and others as to what to expect from it.

Are you talking to me? ;-)



It is still early, but somehow the output of that last batch does not show all the data that should have been gathered, compare to another month:


Which is quite complete.

Perhaps the analysis is not complete (yet)?
Or is there something weird with the satellite's orbit?


Dominik, there's two temperature graphs here (scroll down a bit). If you want more specific data, you can generate maps through the NOAA ESRL daily mean composites page (temp, SLP, etc; screenshot for how to fill in data).


@Chris Reynolds - I don't know. PIOMAS does really well, only in terms of the standards set by, say, the GCMs. To my eye there are some fairly hefty biases, in particular an underestimation of the thickness in general, but also less variability overall (notably Fig2b has a shallow slope in the scatter plot).

Of course, this latter point suggests that it is possible that PIOMAS could underestimate trends in sea ice thickness - so these biases do not act all in one direction.

There is also plenty of other evidence that the ice is thinning - so the general hypothesis that the final decline in ice extent could be very rapid because the remaining ice is thin is well supported - however, the uncertainties in the absolute values of the thickness are such that it would be really easy to overplay this, and then be confounded if the ice is still there in September 2025.

Account Deleted

Also PIOMAS to me there are other reasons that Arctic's volume sea ice in the Arctic becomes less:

1) Schedule an average temperature of the Arctic
2) The destruction of ice shelves on Ellesmere Island (the oldest fast ice in the Arctic)
3) Data GRACE about ice mass in Greenland.

Aaron Lewis

These days the sea ice seems to be moving faster than it did in the days when cryosat was being designed. If you have a system designed for measuring the thickness of ice just sitting there, and then you try to use that system to measure the thickness of ice plowing along at 20 cm/sec . . .

Account Deleted


In this paper (23 page) the accuracy of measuring the average thickness of Arctic sea ice model PIP3 (ACNFS) is estimated to be 0.31-0.35 meters.

Aaron Lewis

Actual ice volume per se may not make that much difference. PIOMAS does not say whether the ice is good cold solid ice with high structural strength or just a pile of slush that will fall apart when the next storm hits it. I fear much of what we call "ice" has already taken on some of its heat of fusion, and is mechanically weak. We would not be seeing such rapid ice movement, if it was structurally sound. And, as ice moves, internal work is being done on the ice, increasing its energy content and decreasing its structural strength.

Given the ice movement this winter, I expect an exceptional melt season. This will melt out some flow channels, and we will see tidal actions start to take out some of the thicker ice.


Account Deleted

I compared the program area of the old ice (gray area) in 2008 and 2012.

86682 pixels

89769 pixels

Now everything depends on summer weather in the Arctic. In 2008 the Arctic ice could be saved through a cold summer.

"In March 2008, thin first-year ice covered a record high 73% of the Arctic Basin. While this might seem like a recovery of the ice, the large extent masked an important aspect of sea ice health; thin ice is more prone to melting out during summer. So, the widespread thin ice of spring 2008 set the stage for extensive ice loss over the melt season.
In August 2008, the Arctic Ocean lost more ice than any previous August in the satellite record.
In the end, however, summer conditions worked together to save some first-year ice from melting and to cushion the thin pack from the effects of sunlight and warm ocean waters. This summer’s weather did not provide the “perfect storm” for ice loss seen in 2007: temperatures were lower than 2007, although still higher than average (Figure 5); cloudier skies protected the ice from some melt; a different wind pattern spread the ice pack out, leading to higher extent numbers. Simply put, the natural variability of short-term weather patterns provided enough of a brake to prevent a new record-low ice extent from occurring."

Chris Reynolds


Actually I think that PIOMAS does a good job on its own merits. The shallow slope you note is because, as the paper notes, PIOMAS underestimates the thickness of thick ice, while overestimating the thickness of thin ice. The Schweiger paper also finds that the IC-SST run of PIOMAS is conservative, and that's the one that's available as a volume series from the PIOMAS website. i.e. to state the bleedin' obvious - things may well be worse than what PIOMAS is telling us.

Until I looked closely at the PIOMAS data I wasn't convinced at all that the loss of volume in recent years was supportive of a rapid transition to a seasonally sea ice free state. I prefer physics based reasoning to curve extrapolation. If this Spring shows another massive volume loss then I won't be arguing against a rapid transition, I may even be moved to argue it's imminent, but that has more to do with the physics implications than extrapolating any trend it might be setting.

Aaron Lewis,
It all depends on what this Spring brings, but I'm seriously beginning to wonder if the sea-ice is so thin that heat fluxes through it mean ice is melting in the Spring season with much greater ease than before.

___For readers of this blog in the UK______

Tonight's Horizon on BBC2, 2100, is entitled "Global Weirding" and is about the links between recent years weird weather and AGW.



Thanks for the link!

I became convinced last year that high tides were having a noticeable effect, at least on the fastice off Ellesmere and NW Greenland. The breakup of the NWP also seemed to be effected.

When we get a little further into melt season I'll again be following at least hi-tides.


Pete Williamson


"..... but an even higher and later maximum, and I'm shutting down the blog"

The CT interactive graph (http://arctic.atmos.uiuc.edu/cryosphere/arctic.sea.ice.interactive.html) shows 1982, 1999, 2010 and 2011 all show resurgences in ice area even after day 90 (as late as day 99) which come very close to beating the earlier maximum. You could be risking your blog over this.


Indeed, Pete. And CT has been slow to update again, so maybe they are double-checking another 200K uptick. 'Just' 125K would do the trick.

Pete Williamson

Chris Reynolds,

You seem to know alot about PIOMAS and ice volume so I'll direct this to you.

The PIOMAS website (and the kwok paper) states that the model assimilates ice thickness observations. Presumably this data contributes in some way to the ultimate output of the model. The Kwok paper you link attempts to validate the model output by comparing it to ice thickness observations. To my mind there seems to be a circular process going on here. Obs are used to constrain the model and then later used to validate it. But it could be argued that they have only validated a very tiny part of the model output (the part that coincides with an obs) while the vast majority of the output from the model is unvalidated.

This wouldn't be a problem if it can be assumed that this tiny part is no different to the rest of the output from the model. But this isn't necessarily true because this also happens to be the part of the output that is most likely affected by the assimilation of obs data points.

This is confusing me somewhat but I hope I've got across the problem as I see it.

Pete Williamson

ignore the above I mis-understood the website



Next two days at 13.546 and 13.552 so now it takes 149k.

Only 2006 and 2011 show a rise of more than this from day YY.2301. However, 1998 1996 1981 and 1980 would get within 20k and 1992 within 45k. 7 out of 33 still getting close seems a not insignificant risk.

Fortunately, I think we can expect further declines in Bering and Othotsk and Northern Kara from weather forecasts. Unfortunately, DMI does show a bounce back up that we haven't yet seen at CT.


The blog is hanging by a thread, people!

Kevin O'Neill

Hanging by a thread?

Hmm ... I would have said the blog is on thin ice...

Kevin McKinney

"I would have said the blog is on thin ice..."

Yes, that would be the preferable metaphor!

BTW--and cross-posted from Tamino's--a bit of musico-lyric foolery (which some here might enjoy) can be found here:



On thin ice? That's so 2008!

Maybe I should have said that the blog is hanging by this particular thread? :-P


Nice musico-lyric foolery, Kevin. Will we see the day "denial dies"?

Kevin McKinney

Thanks! I sure hope so...

BTW, my pointer didn't go where I initially thought it did, which was to a host page giving credit to the lyricist and the 'inspiration.' (Don McLean, as most will readily recognize.) The lyricist was (not surprisingly, perhaps) 'Horatio Algeranon.'

Chris Reynolds

Pete Williamson,

I wrote this before seeing your 'ignore' message - so I may as well post it. :)

Although I don't think it's what concerns you, there is a danger of circularity here, particularly in the region of the central Arctic covered by the submarine data release area (DRA). Indeed the Schweiger paper points this out. However crucially not all the thickness data was used in the development of PIOMAS, and the correlation between PIOMAS results and ice thickness data that was not used in PIOMAS development is identical (0.73) with that used in PIOMAS development.

With regards the issue of assimilation. PIOMAS assimilates ice concentration and SSTs, its atmospheric environment is driven by assimilation of NCEP/NCAR reanalysis data. So PIOMAS isn't like a common GCM model, it's an assimilation model. This is vital in the current situation because we're on one 'realisation' of climate change. If we had a series of identical earth's to carry out the experiment of AGW we'd see that even though forcings might be identical those earths wouldn't follow the same path of climate change, for example it would only be on our Earth that 1998 saw a super-El-Nino, and 2007 saw a massive Arctic sea-ice crash. Other earths might see similar events at different times, or not at all. Imperfect as they are the models are the nearest we have to the experimental ideal of a series of parallel Earths.

However for trying to figure out what is happening on our Earth, the one that really matters to us, a set of model realisations that represent other realisations of the path of climate change have some use, but it's not the exact same path we're on. Here's where assimilation comes into its own: By assimilating observational data it's possible to force the model to track the specific track of climate change that we're on. The NCEP/NCAR atmospheric data is another example of a model being forced to track the real world by assimilation of observations. NCEP/NCAR reanalysis uses a physics model to 'fill in the gaps' between observations.

As PIOMAS is mainly used as a proxy for sea-ice thickness the assimilation of sea ice concentration doesn't really present a problem of circularity. The unknown variable is thickness or volume, nobody would use PIOMAS for area or extent as we have these from satellite observations. As PIOMAS reproduces known thicknesses and known events such as 2007, it seems its volume and hence thickness data is sound. There are qualifications, such as the underestimation of thickness of thick ice and overestimation of thickness of thin ice, but provided these are kept in mind PIOMAS can be used safely IMO. With regards this thickness qualification, given that the ice pack has transitioned from mainly multi-year sea-ice (thicker) to a mainly first-year sea-ice (thinner), that qualification errs on the side of a conservative estimate - there is now more thin FY ice and PIOMAS probably overestimates the thickness of that.


Now I suspect you can appreciate why I stay out the whole day to day commenting on the viscitudes of the ice. But don't let that stop any of you - it's an interesting read.

Does this make me cowardly?


Now I suspect you can appreciate why I stay out the whole day to day commenting on the viscitudes of the ice. But don't let that stop any of you - it's an interesting read.

Does this make me cowardly?

Of course not.

It's like the difference between climate and weather. You can look at the long-term trends and the physical basis trying to explain them. You can also look at the short-term, a bit like you would look at weather maps. The emphasis is on the latter on this blog, although a bit of the first is done as well, as long-term and short-term are interrelated, of course.

Like I wrote in the very first blog post:

for years I've been missing a central place where the situation in the Arctic can be discussed. I always had to glean information and explanation from little corners of the comment sections of blog articles, so let's see if the Arctic deserves its own blog.

There's a need for knowledge about the immediate, the weather, as well as a need for knowledge concerning the more elaborate context to put actual events into perspective, the climate. I think there are a couple of blogs now (see blog roll on the right) who are increasingly taking care of this combination, together with larger blogs/websites, such as SkS and ClimateProgress. It's a good combination, I think.

I for one lack the skills and brains for the long-term analysis, but I'm becoming better at the weather watching. And why shouldn't we? We have the tools (see the Daily graphs page) and it is happening as we speak, even if it takes the Arctic 25 years to become ice-free in September.

Dominik Lenné

First thank You Peter for Your clarifications on CryoSat and the links to the beautyful images with the web of satellite tracks - and to Neven concerning the data sources.

Concerning ice-freeness, I see two approximative parameters: the steady state summer ice area for a given mean arctic temperature/radiation situation, and the time constant of the adaption to the new regional climate. Latter can be estimated from the much discussed "no tipping point" - study (http://www.agu.org/pubs/crossref/2011/2010GL045698.shtml) in the order of magnitude around 2 years for the tinner ice - may be a little bit more for the thicker. As one can see here (http://imb.crrel.usace.army.mil/2006Csum.htm), even 3m of ice can easily be molten down in one summer. Concerning the former: when we'll reach near ice-freeness depends, I think, much more on how regional climate will develop than on how much ice volume is there actually. I believe (believing is not knowing) that even in case PIOMAS underestimates ice mass, this does not make a big difference, if regional temperature rises continue. Summer ice will remain in those places where the mean temperature is low enough. The "citadel of frost" is the decisive point of the summer ice battle.

Pete Williamson

Thanks Chris I'm glad you carried on with the answer, very interesting.

I've wondered what would the ice thickness data look like without the conditions that caused the big clearout of ice in 2007. For example would it be possible to run an experiment where the 2007 data is replaced by a more neutral set of data then go back to the real world data in 2008 onwards?


Within 64k of peak and 10 of 33 years show rises of more than that from day yy.2384

There is more ice so that thin ice is getting thinner? Something is wrong with this metaphore? ?)

But DMI is going down and another low taking aim at Okhotsk means ice area should be going down in next few updates.


Yes, the uptick or stalemate is caused by the ice in the Arctic Basin, Barentsz and Okhotsk.

How incredible would an even later max date be? Three weeks later than in the past 7 years. Wow.


And the global SIA anomaly will go positive as well now.


Now what happens??



That's it, I'm closing the blog.




and quickly open it up again ;o)

Chris Reynolds

Pete Williamson,

PIOMAS could do that pretty easily - instead of using the NCEP/NCAR data for 2007, just use another year's data. I presume it would set the progress of volume loss back somewhat. However since 2007 most of the increase in volume loss has been due to an increasing proensity towards Spring melt. The following graph is daily PIOMAS anomaly by year for the last 10 years.

Regards cowardly - leave off the winking emoticon and it changes the tone entirely. ;)

L. Hamilton

DMI is going nowhere fast, but as of 3/30 remains 130k below its high point reached on 3/20.


I've put an update at the top of the post.

What's weird about this extra late max thought, is that I didn't really see it coming on the UB SIC maps, comparing day by day. But that's the eyeball method for ya.

Jim Pettit

Call me dumbfounded. The latest maximum on record by a full week; nearly 800,000 km2 more ice than on this date last year; and nearly 1.1 million km2 more ice than there was on this date in 2007. Two more days of growth and we'll be in April; think we'll make that? How about a June maximum? Can I hear July? ;-)


It looks like for the first time since March 2003 we may have a positive SIA anomaly in the NH ( it was a very close call in April 2010!). I have the feeling that 2012 will surprise us all...


Only comparing the shapes of the 2010 and 2012 CT SIA graphs, the graph of 2012 is very similiar to 2010, while the shape of the ice extent is quite more different ->


Chris K


This is conclusive proof that Steve Goddard is a genius, Monckton is an honest man and Anthony Watts is an impartial scientific observer.

(Happy April 1, everybody!)

Account Deleted

I remember last summer, Steve Goddard promised that the area of old ice in the Arctic grow.

"In 2013 there should be an increase in the amount of five year old ice, because that is when the 2008 ice will have aged five years."

Who now believes that the old ice in the Arctic is restored?


Some beliefs are easily maintained. If you check out the progress of old ice on these two items http://neven1.typepad.com/blog/2011/07/new-paper-from-maslanik-et-al.html , http://www.nature.com/news/2011/111012/full/478172a/box/4.html you'll see what I mean.

I only had to squint a lot while standing on my head looking through the bottom of a beer bottle and I could see the prediction is spot on. Simple really.

Account Deleted

It was only a short "recover". Recent reports indicate that the old ice was reduced to 2008 levels.

Many other data also suggest that the Arctic warming is catastrophic.

Greenland ice is decreasing every year.

The albedo of the Greenland ice is falling every year.

Ellesmere Island ice shelves (the oldest fast ice in the Arctic) are rapidly destroyed.

This suggests that the process of melting the Arctic is now reminiscent of an avalanche, and I do not believe that the process to apply to the other side.

Jim Pettit

Here's a little chart I threw together to highlight the outlier nature of this year's SIA maximum:

SIA maximum day

Full-sized image here: http://bit.ly/Hxt22h

Pretty anomalous, no?


After one of his great public lectures on quantum mechanics, in which he explained how physicists understood the properties of atoms with an accuracy in the order of a 15 digit number, Richard Feynman was asked if he thought his theory was going to be proven wrong at some point.

Feynman answered that, although he could not see beyond the event horizon of scientific knowledge, philosophically speaking, every scientific theory at some time had been proven wrong but that quantum mechanics was the best tool available at the moment to describe how everything works.

This day (or more exactly:yesterday) could go into the history books. Have we have witnessed the defeat of Feynman' greatest achievement? This late sea ice maximum surely disproves the known quantum mechanical properties of CO2, right?


2010.2493 13.7320328 was only beaten on 3 days in 2010 so I am not sure it should be regarded as all that unusual.

Account Deleted

In addition, recent observations of the level of the ocean say it again near the maximum values.


This suggests that global warming continues. The water temperature in the ocean increases, the polar terrestrial glaciers are melting.

Account Deleted

"This day (or more exactly:yesterday) could go into the history books. Have we have witnessed the defeat of Feynman' greatest achievement? This late sea ice maximum surely disproves the known quantum mechanical properties of CO2, right?"

It just says that in winter in the northern hemisphere sea ice has more variables than in summer.

Global warming is primarily the level of the ocean like a giant thermometer, which shows us the global temperature of the planet.

Kevin O'Neill

As has been noted the SIA this year is tracking 2010. While this may just be coincidence, there's always the possibility that this similarity is the result of equivalent forcings. We better hope it's just coincidence.

2010 saw a reduction in volume nearly as dramatic as 2007's reduction in extent. If 2012 sees *another* drastic reduction in volume akin to 2010 - then Neven might as well rename this the Arctic Sea Ice Open Water Blog.

Kalle GZ

Hey Neven, I have been following your blog since early 2011 and I finally decided to make an account on here.

Also, a 3K drop in area reported for the 31st, unsure if we reached the maxium on the 30th or not, but I was very impressed on the late maximum.

A maximum in April will be very impressive indeed, though.


Kalle GZ wrote:

Hey Neven

He is out for some holydays now...

Kalle GZ wrote too:

A maximum in April will be very impressive indeed, though

Yes it would, but it won't happen as temperatures are up, very up in the Hudson Bay as well as in New Found Land, Hudson strait en the entire Baffin Bay.


>"I'm not calling this one anymore, ever!"

Maybe I shouldn't either. But with area 229k below the peak and largest increase in 33 years from YYYY.2521 being 177k, DMI not showing any recent increases and the weather looking set for further losses, then I think it is reasonable to call it with at least 95% confidence.

Besides if you never say anything to avoid ever being wrong, you don't get the pleasure of being right. ;-)

Seke Rob

Think it's the Dutch who have the "spout 11" expression, a very late addendum in L.Hamilton chart format. As noted, the SIA max was the latest since CT records began, but far from the highest.


-- Rob

P.S. Minimum prediction, Sept 17, 2012
(Wet finger in the air and fortunately, the 17th is not a Friday... the winds might blow in the other direction)

Kevin McKinney

Oops! Same link for both items, Rob--I don't think that's what you intended?

Seke Rob

Copy / Paste devil, but the link can be constructed from the intended topic http://bit.ly/CTNHMn

A small ending n this time.

(still way off the scales :)

-- Rob

Kevin McKinney

Too funny!

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