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Do you mention the sudden finish for how thin the ice is at places? CAA, ESS of course, but also much of the periphery at the pacific side...

Robert S

I've never been completely convinced by the PIOMAS volume loss associated with 2012's GAC. It was such a dramatic compaction event that it may have pushed the model outside of its range of accuracy. On the other hand, the extent loss truly was dramatic.

Whether or not 2019 breaks 2012's record, it will be close enough, and looks like a function of the "new normal", where-as 2012 was a unique event. That in itself is reasonably scary.

Looks like there may be some ice export down the east coast of Greenland over the next week. Winds have been keeping that area reasonably compact, so decompaction in this area will impact the extent numbers, although also dooming the exported ice.

Doc Snow

As of 8/8, 2012 is opening up a lead... no pun intended, of course. Another straw in the wind that we won't see a new record this year, though of course nothing is "settled" yet.


Well the GAC is over and the extent difference is only about 200K above 2012. PIOMAS becomes less accurate as the ice gets thinner so the difference now with 2012 is probably within the margin of error. It has been a hot summer in the Arctic particularly above 80N which suggests plenty of capacity for late melt.

A couple of years ago a suggested formula for Area and Volume was posted on the forum.
Area = 1.282(Volume^0.5136).
This formula predicts an increased decline in Area once volume drops below 5K km^3 as occurred in 2012 and a precipitous decline when it drops below 3K. It will be interesting to see if the same process occurs this year.

James S.

DavidR, can you provide the source of that surface area-to-volume equation?



Doc Snow

"...the GAC is over and the extent difference is only about 200K above 2012."

Yeah, in fact as of yesterday (8/11) JAXA had it at 110K. And it's early for this last phase of things, but the slope of the decline so far looks about the same as that of 2012 post-GAC.

So maybe it's more of a horse race than I thought it might be last week. The Arctic weather gods still have lots of scope for action. And if I'm reading the weather outlook right, said gods want to keep the ice melting rapidly for another few days at least.

Robert S

The plume of Siberian wildfire smoke being sucked out across the ice is truly impressive today. Lots of heat with it, too. Meanwhile the Northwest Passage is within days of opening unless there's major ice movement south. We could have close to a month with both the Northwest and Northeast passages open. Circumnavigation opportunity if anyone is positioned...


Where can we see the Siberian smoke plume, Robert S? Could you please post a link?

Robert S

javimozo: See for instance https://worldview.earthdata.nasa.gov - set the view to arctic and, depending on the time of day, step back a day for a full view

Doc Snow

2012-2019 gap still at 110K, per JAXA. More and more interesting.

The Arctic weather outlook remains generally pretty warm. And am I right in thinking that the weather patterns have been favoring ice export via Fram? (That's what I think I'm seeing on the Reanalyzer.)



You ask a great question. I too have been watching the forecasts and it sure seems like there are favourable conditions for ice export. I don't dig far enough into this hole. Maybe someone else here does.



Thank you, Robert S.


I've never heard it explained as to why <1M km^2 defines "a sea-ice free Arctic".

Why then should anyone expect that that particular number will ever be breached?

On the forum a few days ago someone put up a formula relating Arctic Sea-Ice-Volume to Arctic Sea-Ice-Area... basically it went down at an increasing rate once Volume went below 5, and it went down precipitously if Volume went below 3. (Obviously I can't find the thread at this point in time or I would have left a link to it.)

Doc Snow

The sub-1M km2 standard is essentially arbitrary. The idea is that at that level, the Arctic basin would be essectially bare, with just some bits floating round and/or landfast in sheltered locations.

Why should it be breached? I'm not sure I understand the full context of your question, but basically because of Fudd's Law: "If you push something hard enough, it will fall over."

Fudd's is obviously non-quantitative, in contrast to actual scientific laws, but given that the energy required to melt all the Arctic ice is finite; that annual minima are only about 20% the volume they used to be; and that we may confidently expect both air and sea temperatures to keep climbing (as well as GHG radiative forcing) for the near future; we appear to be in a Fudd's-type situation. Energy available for melt is going to keep increasing, while ice volume keeps decreasing, until the system 'falls over'.

The analogy fails a bit at that point, because seasonal refreeze won't stop then--though it does appear that a perenially ice-free Arctic Ocean is in fact a possibility:

"Fossil records verify that during the Eocene period, 50 to 55 million years ago, there was no permanent polar ice on Ellesmere Island. Instead, a lush rainforest dominated by dawn redwood trees and tropical vegetation flourished near Strathcona Fiord. This fertile ecosystem survived despite being shrouded in darkness for six months of the year. The forest thrived on rich flood plains that teemed with a diverse variety of life, including alligators, tapir, giant tortoises, primates, snakes, lizards and the hippo-like Coryphodon, all nourished by the abundant rainfall and mild climate."


Doc Snow

As of 8/18, 2012 has opened up a bit more 'space', with the difference from this year up to ~250k. (Interestingly, that 2012 value for August 18th--4.31 million km2--is also pretty close to the 2010s average for the minimum--4.39 million km2). I expect 2019 to hit that mark later this week, barring sudden changes in conditions.

It looks to me as if the chances now favor a 2nd-lowest-ever minimum in about 3 weeks.


The latest update from NSIDC says that the average sea ice thickness for that date is about half what it was in the 80s.


Maybe I'm just crying wolf again, in which case I do apologise, but that's the forecast in 2 days time:


and in 3 days time:


It could be worthy to keep an eye on it.

Doc Snow

As of 8/23, the separation with 2012 has increased to nearly half a million square kilometers, so you'd have to say that 2019 is fading badly in horse race terms. Good for the Arctic and planetary environment, less good for humanity's awakening, perhaps.

Interestingly, despite what would appear to my not-very-acute eye to be pretty favorable conditions for melting, even a second-place finish is now somewhat in doubt, if you go by the current decline. Project the 2019 graph line forward, make your best guess at when the minimum turns out to be--conveniently, 2016 (early) and 2007 (late) more or less bracket the range--and you likely end up with 2019 somewhere in the vicinity of those two years, which is to say around the 4 million mark.

It took a little longer than I expected, but 2019 has indeed roughly equaled the minimum of the 2010s average now--more precisely, 2019 is at 4.41k, while the 2010's average bottoms out at 4.4 for the dates 9/12 and 9/13--so a finish that's well below the decadal average is in the bag.

I suppose it would be well to mention once again, for folks who are jumping in now, that this is all per the JAXA extent data, which may be found here:


(Hope that link holds--otherwise, JAXA extent is in the excellent collection of 'house graphs' which Neven curates, accessible via the "Arctic Sea Ice Graphs" link in the upper right of this very page.)

Doc Snow

As of 8/23, JAXA extent is definitively below the decadal average for the annual minimum, @4.38 million km2.

However, I'm scratching my head, because the decline for the last week plus has been below historic norms, despite what to my not-so-acute-weather eye would appear to be conditions reasonably favorable for melt. Just a few more days like this, and 2019 will cross the 2016 track into "#3 territory."

Anyone feel like they know why that is?

Robert S

Doc Snow: I've been observing some signs of decompaction. That's the essential problem with extent as a measure of total ice. 2012, with the GAC, was a compaction event, which exaggerated the ice loss when measured using extent.


I fully agree with you, Robert S.

That difference in compaction you refer to is clearly dicernible when comparing today´s University of Bremen sea ice concentration data


with the same day data 7 years ago


Doc Snow

Robert, javi, thanks for that.

Well, sort of 'thanks'--it means the ice is more in reality much more fragile than in 2012, while we don't get the same messaging 'pop' with the general public as would be the case with a straight-up low extent. But 'it is what it is.' And I appreciate the knowledge.

What about cloudiness over the period of the recent melt 'slowdown'? Has that been playing a role? (There seemed to be a hint of that in one or two of the Forum comments I looked at.)

Doc Snow

Wow, we're now entering the "orbit" of 2016, which, on 8/29/16, stood at 4.4 million km2. (2019 is at 4.33.) Since the decline in 2016 was much more rapid over the 'next few' calendar days than has been the decline over the last few days this year, it seems likely that we'll shortly fall behind 2016 in the 'horse race'.

And I'm wondering about the explanation suggested above by javimoto and Robert S, in that while it is true that the concentration maps continue to show a lot of broken ice over wide areas, the actual sea ice area map from ROOS has showed an *increase* in area over the last week or so.

Yet the JAXA extent isn't yet quite flat.

I'm feeling quite unsure as to what is happening with the ice this August, let alone why! I don't recall a melt season finale quite like this one, and I've been watching them for a while.

Doc Snow

Intersection! As of 8/30, both 2019 and 2016 sat right on 4.3 million km2--and so in a second-place tie for the date (per JAXA).

Slightly ironically, 2019 also posted the biggest daily drop in a while--30,000 km2. But 2016 posted considerably larger drops than that over the first few days of September, so the odds have to be that 2019 will be going into third shortly.



James S.

I've been tracking this for awhile and thought folks might be interested. Data are from JAXA Arctic sea ice extent site--thank you again Neven for aggregating data sites! April 1 and September 1 values were used to avoid annual variations near maxima/minima. The decadal data (Sea ice extent x 10^6 km^2) are averages as reported by JAXA. Semidecadal data are medians.

Years April Sept. delta
1980s 15.2 7.4 7.8
1990s 14.8 6.7 8.1
2000-04 14.6 6.1 8.5
2005-09 13.8 5.3 8.5
2010-14 14.2 5.0 9.2
2015-19 13.6 4.4 9.2

The interesting, dare I say alarming, observation is the growth in delta values between 1980s and present.

Doc Snow

...and sure enough, as of 9/1, 2019 is at 4.25 million km2, 80k behind 2016, for third place.

If there's a late minimum this year--as there was in 2007--one could imagine 2019 repassing 2016, but if there's not, then 2016 will pretty definitely keep its second place laurels for at least another year. And if there's a *really* early minimum, 2019 could end up in fourth, behind 2007.

I've been having very little luck this year sussing out short-term melt from the weather maps, so no guesses from me at this point!


Is not worldview currently showing the potential for masssive Fram export?

Doc Snow

9/3 JAXA update shows this year at 4.21 million km2, 20k ahead of 2007, 120 behind 2016. The decline seems to have returned to more typical decline rates after its 'slowdown,' though. Second place may well be in play, still.


Doc, does worldview seem to you like it's showing potential mass export is about to occur through Fram?

Doc Snow

The 9/4 update shows a sizable drop of 50k, for a 20k 'gain' on 2016. The numbers for 9/4 look like this:

2007: 4.33 (+920k)
2012: 3.41 ('leader')
2016: 4.06 (+650k)
2019: 4.16 (+750k)

With 2016's decline slowing over the remainder of the season--that year bottomed out at 4.02--there is a reasonable chance that this year could now re-emerge as a second place finisher, should melt continue for, say, 10 more days.

AJBT--"Doc, does worldview seem to you like it's showing potential mass export is about to occur through Fram?"

I don't really know, as I don't use worldview much--I've just never put in the time to get familiar with the various filters and such. I have seen, or thought I saw, some indicators of Fram export in the surface winds on the Climate Reanalyzer, though. If anyone knows more about the topic, I'd be delighted to hear more about it.

Doc Snow

Looking once again at the Reanalyzer, it seems to me that Fram export over the end of the melt season may be a bit on-again-off-again.

But it also looks as though most of the Arctic is going to be dominated by low-pressure systems, barring the inevitable Greenlandic high (and also higher pressure over the Canadian archipelago.) Should that mean generally cloudy skies, combined with the very definitely elevated SSTs currently prevailing, I'm guessing we may indeed see some sustained late-season melt. We'll soon know.

Doc Snow

"We'll soon know," I wrote.

Have you ever felt as if the Arctic is actually trying to mock you, though you know perfectly well that that is the rankest sort of anthropomorphism?

I have.

And that's the feeling I have today, 'cause the JAXA extent number for 9/5 came up with a 20k *increase* in extent!

I'm not even going to bother with Climate Reanalyzer today; I'll just come back tomorrow and see what has happened, and until then, I'm keeping my mouth shut on the topic of ASI.

Doc Snow

For 9/6, 2019 holds steady at 4.18 million km2, as 2016 likewise holds, but down a bit at 4.02.

But 2007 is coming up (or, more literally, "down") fast, at 4.24. Its minimum value--reached twice, in an unusual 'double dip' minimum--was at 4.07.

Doc Snow

9/7 sees us down a tick at 4.17.

Naive extrapolation--my favorite kind, as you probably noticed--suggests the possibility of an SIE 'triple point' on 9/11, a date which has 2007 at 4.13 and 2016 at 4.12. The final order of finish still depends on whether or not 2019 has 'legs'.

G man

Well it's looking like the end is here or very near abouts. Another year with a climate change research ship stuck in the vanishing Arctic ice .The NWP barely open. Oh well I'll give it to you guys you hang in to the bitter end hoping for the collapse that's "just around" the corner. I do indeed like checking in with all the doom and gloom. Cheers till next spring when hope "springs" eternal.


Glad to be of service. Now all we need for you to be really happy, is a return to pre-2005 levels. And then all will be well, as it always has been, and always will be.


Bad weather for Australia is being predicted as a possible breakdown of the polar vortex around Antarctica appears likely!

Doc Snow

9/8: 4.16 million km2
9/9: Back up to 4.17

Was that the minimum? Maybe, but it's still too early to call it. Based on the historical record, further declines will be a possibility for at least a week.

The other news of the day is that for 9/9, 2007 stood at 4.17, so there's a tie for 3rd place right now. But 2007 is the poster child for a melt season with 'legs', having been at its nominal minimum of 4.07 on several days between 9/15 and 9/24.

In that respect, 2007 was a real outlier. So chances now are, I think, that 2019 is going to end up as the 4th-lowest minimum.

Apparently G man thinks that's some kind of triumph for 'his side.' I call it pretty cold comfort for humanity, but then I can't resist a pun, even when it's low gallows humor.

Jim Hunt

I am extremely curious to learn which "climate change research ship" allegedly became "stuck in the vanishing Arctic ice" earlier this year?

In case it's of interest to regular readers Oden didn't become stuck in any sea ice when checking out the "remote Ryder Glacier in northwest Greenland" recently:


What's more Polarstern will intentionally become stuck in the vanishing Arctic sea ice in a few weeks time:


G man

Cheers to you Neven. Even if we disagree philosophically I do respect the work you put into the forum etc...

Doc I don't see it as a "triumph" at all. 2012's record low was mostly dependent on the Arctic cyclone, a weather event. It wouldn't be a stretch to say that this years ice extent without the cyclone is even lower.I'm just patiently waiting for the AMO and PDO to flip and then we can actually see a full climate cycle. Hopefully I have enough years left to see that.

Jim that would be the MS Malmo which just got stuck near Longyearbyen.

Jim Hunt

Thanks G Man - It's not spring yet though!

The MS Malmö isn't a "climate change research ship". Allegedly it is "a homely ship of maritime historical dignity" which "has been listed as a traditional ship of cultural value since 2004":


Perhaps you could persuade your sources to do their due diligence a bit better in future?

G man

MS Malmo was retrofitted in 2014. Upgraded for sea ice. While technically a "tour" ship it was carrying a crew of 16 passengers a documentary film team, and tourists, concerned with Climate Change and melting Arctic ice. All 16 were evacuated by helicopter in challenging conditions, all are safe. 7 crew remains on board, waiting for Coast Guard ship assistance.

Arctic Tours ship MS MALMO, IMO 8667579, dwt 466, built 1943, refurbished in 2014, flag Sweden.

Jim Hunt

Mornin' G Man (UTC) - You're still just regurgitating your utterly inadequate sources. The Malmö isn't currently "waiting for Coast Guard ship assistance" for example. It wasn't when the cryodenialosphere went wild with the "news":

Perhaps you'd be good enough to tell all the other "rebloggers" of the same "story" about the happy ending?

Doc Snow

Um, G-man, the PDO "flips" all the time:


The AMO, true to its name, not so much:


But it's a regional phenomenon. And the fact that we've been seeing historically low ice extents during this declining phase of the AMO demonstrates that the AMO is *not* in the driver's seat, so to speak.

Doc Snow

Jim, I do love a ship with a "lovely patina!" :-)

Doc Snow

Hm, weird--my update on the 'horse race' just disappeared upon posting.

To reiterate, hopefully with more success:

As of 9/10, 2019 sat down a tick at 4.15 million km2 in the JAXA data, while 2007 was another tick lower than that, at 4.14.

From here, 2016 will have made a rapid ascent from minimum--that year featured an early minimum. So in a couple of days, we could have that 'triple point' I speculated about in the last comment. In fact, I almost want to say it's likely, based on the guess that 2019 won't take off on a strong positive or negative excursion before then.

Jim Hunt

Doc - You and G Man will no doubt be overjoyed to learn that MS Malmö has now reached Bear Island without sinking:


Whether her brief encounter with some sea ice has improved her patina or not remains to be seen.

Whether the 2019 minimum extent has occurred yet also remains to be seen. At this juncture it seems entirely feasible that different versions of the metric will come up with significantly different dates!

The NSIDC daily minimum currently sits at 4.24 million km² on September 4th.

Jim Hunt

I foolishly ventured on to Twitter this morning, where I discovered some nice pictures of the sea ice off the east coast of Svalbard courtesy of the Norwegian Coastguard, plus Matt Ridley regurgitating the same garbage as G Man.

I felt compelled to reply!


Doc Snow

Jim, I am indeed pleased by the escape of all those middle-aged Norwegian tourists from (nearly) Certain Icy Death. But I'm "overjoyed" by finally getting something right about this year's melt season: 9/11 was in fact marked by an ice 'triple point' (at least to a reasonable approximation).

To celebrate, I went so far as to do a screen grab of occasion, as you can see below.

But just in case the numbers are hard to read, let me do a table, too:

2007: 4.13 million km2
2016: 4.12
2019: 4.11

So obviously 2019 is once again second-lowest for the date. Notably, the drop from 9/10 is a pretty-impressive-for-the-date 40k. I'm guessing that that can pretty readily happen with a whole bunch of pretty trashy ice in the mix. (But I'm probably returning to form and being wrong again.)


Jim Hunt

Doc - Your JAXA graph is blurred out behind a photobucket ad when I look at it. Here's a cropped version of my equivalent image to illustrate your point:

along with my own musings on the 2019 metric minimum season:


You may also be interested to learn that a certain Donald Trump has been promulgating the "Climate Change Warriors got stuck in the ice" meme on Twitter? My alter ego took it upon herself to try and set the record straight:




I am eagerly awaiting the September update of the Arctic Sea Ice Volume numbers. In the mean time, thank you, Doc Snow and Jim Hunt for keeping the sea ice extent numbers updated.

I know that some of you would like to see a record low extent or volume in order to alert the world to the impending climate crisis, but for the same reason, I'm hoping no record is set as personally I'm not convinced that CO2 is really the climate culprit.

G Man, I think you gave in too quickly. You said, "Doc I don't see it as a "triumph" at all. 2012's record low was mostly dependent on the Arctic cyclone, a weather event. It wouldn't be a stretch to say that this years ice extent without the cyclone is even lower."

But, if we go back and look at March, 2019 looked like it was actually going to be a pretty healthy year insofar as Arctic ice is concerned. Wasn't it an Atlantic cyclone that knocked 2019 off track to begin with? If that is the case, what good would it do to crow about 2019 if a record were indeed set? Wouldn't that be a bit misleading? Which is why I hope no record is set, though we are dangerously close to record territory.

Elisee Reclus

Perhaps it's still too early to say for sure that rising CO2 levels and other greenhouse gases generated by human agricultural and industrial activities are the cause of global warming. Still, its the explanation that most closely corresponds to the observations, isn't it? No other excuse can offer as convincing a fit to the facts as a side-by-side comparison of CO2 PPM and SIE curves.

The resistance to the obvious hypothesis has nothing to do with science, it persists because the human genesis of climate change is a threat to the ideological paranoia and entrepreneurial fantasies of the denialist community. And lets not forget history, we've seen the same tactics employed against pesticides, tobacco carcinogens, and lead gasoline additives. Follow the money. And as Bobby Zimmerman tells us, "Money doesn't talk, it swears."

The Keeling curve goes up and the SIE time series data goes down--not just for September, but for every single month of the year! Maybe it is changes in the solar constant, volcanic outgassing, cosmic rays or some other unexpected factor, but I haven't heard even a reasonable hypothesis yet as to what it might be or even any anecdotal evidence as to what it could be.

Yes, the data is noisy, but the slope of the linear regression of the SIE for the entire time the satellites have been working is unmistakable. That is simple, unambiguous data from one sensor, showing a 50% drop in a key metric in only 40 years.

Consider this, the trolls come out as soon as it looked like the 2012 record wouldn't be breached, but they were as scarce as hen's teeth just a few days ago, weren't they?

Jim Hunt

DrPhil - Here's an extract from the latest PIOMAS graph

You can examine the whole thing at:


With luck a mid month update will be along in a few days.

FYI JAXA has (barely) posted a new minimum of 4.09 million km².

I think you'll find that persistent high pressure over the Arctic was what "knocked 2019 off track". This year the early cyclone caused dispersion into the Beaufort Sea:


Jim Hunt

Elisee - The trolls are certainly out in force now!


Doc Snow

Thank you, Jim! Photobucket is trying to force me to become a paying member, apparently.

Your fix is much appreciated.

Elisee, I don't think it's "too early" at all. After all, the IPCC called it at least two iterations of the Assessment Report back. And it's not as if we have to work from a statistical null: we *began* with physical theory predicting this, and as you point out, we are lacking any other successful explanation. (Not that alternatives haven't been proposed, but none have withstood testing to date.)

As Jim said, 2019 has managed a 20k drop--not so shabby for this time of year--to 4.09 million km2. That's 40k ahead of 2007, and 110k ahead of 2016 (for the date of 9/12).

Relative to the respective minima, 2019 needs to eke out another 20k to equal 2007, and another 70k to match 2016. Pretty darn close...

Elisee Reclus

No doubt all of you are familiar with the NSIDC website's interactive graph


that allows you to turn on and off the display for each year's SIE curves. If you do this in chronological order, you get the time dimension .

Its all the proof I need that the climate is changing, and fast. And the direction is clear. The data is noisy, but if you display it like this there is no denying what is going. And the denialists know this perfectly well. They just have convinced themselves they can profit from this disaster and they are determined to do so.

Maybe we won't break the record THIS year, but the trend is obvious.

Jim Hunt

Elisee - See also this recent NASA video:


It shows sea ice age, and hence volume, declining more rapidly than extent.

The trend is even more obvious!

Elisee Reclus


There are other metrics that are more persuasive than Sea Ice Extent, which can be made noisy by local or short term wind and sea conditions. But I prefer to use SIE because:

1) There is an unbroken, consistent record going back 40 years through the SAME sensor.

2) Because of that, the year-to-year ice loss is directly comparable. There may be variations due to weather and current, but they tend to cancel out in the long run. The resulting trends, as shown by the monthly SIE average cover time series, allows a linear regression to be drawn for each month, and they are all dropping over the years, even at the height of winter. Also, the negative slope becomes even more extreme as you approach the summer. It is hard to explain that in any other way except that the Arctic is responding in an amplified way to global warming.

3) The averaged monthly SIE coverage smooths out a lot of the day-to-day variation as plotted in the NSIDC monthly report graph. The yearly minimum may be an outlier or a statistical fluke, but the averaged minimum is a more robust measure of long-term trends than any daily reading

4) SIE gives a better idea of how much solar insolation of blue water is occurring.

5) Metrics like sea ice volume are determined by modeling, and can be too easily attacked by denialists as biased. The SIE raw data is right off the satellite with nothing to mess with the signal. That leaves them nothing to cherry-pick.

The 2012 minimum was a perfect storm situation, a true outlier, a statistical anomaly. It so far exceeded the normal ice loss trends that it has tended to obscure the fact the ice is still melting. That's why we haven't had a record low for 7 years now, while record minima in the past have been, on the average, about 4 to 5 years apart. If we simply removed 2012 from the interactive NSIDC graph, the overall trend would be even more noticeable. But the denialist community tends to point out the failure of the 2012 record to be broken as evidence of some kind of "recovery".

I find the efforts made by the denialists to make this problem go away by discrediting their opposition extremely disturbing--it is akin to arms trafficking or war crimes. This is not a question of a difference of opinion or an honest misinterpretation of evidence. It is a deliberate and systematic effort to see that efforts to solve this problem are delayed for as long as possible. These people know exactly what is going on, and they intend to prolong it and profit from it. Even while they insist the Arctic ice is not disappearing, they are rapidly mobilizing to exploit the blue water to further extract its resources.

They are corrupt and they are ruthless.

Elisee Reclus

A historical note:

From a discussion of climactic provinces in the distribution of intertidal species, Rachel Carson (remember her from "Silent Spring"?) describes a growing awareness of global warming already becoming obvious to marine biologists early in the last century. Again, note the sensitivity of the Arctic regions to climate change. The canary in the coal mine…

"Although these basic zones are still convenient and well-founded divisions of the American coast, it
became clear by about the third decade of the twentieth century that Cape Cod was not the absolute barrier it had once been for warm-water species attempting to round it from the south. Curious changes have been taking place, with many animals invading this cold-temperate zone from the south and pushing up through Maine and even into Canada. This new distribution is, of course, related to the widespread change of climate that seems to have set in about the beginning of the [twentieth] century and is now well recognized–a general warming-up noticed first in arctic regions, then in subarctic, and now in the temperate areas of northern states. With warmer ocean waters north of Cape Cod, not only the adults but the critically important young stages of various southern animals have been able to survive."

from “Patterns of Shore Life” in

“The Edge of the Sea”
Rachel Carson (1955)

She then goes on to describe instances of animals found outside their normal ranges, and changes in historical fisheries resulting from these migrations. Those lines were written over sixty years ago.


One of the most frequently encountered failings of humans is the inability to handle complex information.

Another is the even more dominant and frequent problem of people choosing what data they like. This may be because it supports their tribe, their preconceptions, it brings them money, it avoids things they are afraid of, or ... other things.

Combined they spell trouble.

The simple truth is that all of the data applies all of the time. Projecting based on incompletely understood systems is difficult, and sometimes impossible. Projection based on an inadequate period, and inadequate time basis is prone to bad projections.

In the case here, it is not a matter of choosing extent, or volume, or area. All of these apply simultaneously. Each has issues. Those must be considered.

Volume is largely assessed via modeling applied to data sets. And each of the four or five independent methods provides somewhat different answers.

Extent is assessed using arbitrary rules that were intended to smooth the rough edge and provide a bounded estimate. Extent based on the 15% criteria is highly prone to error as the ice edge moves from being a true edge to encompassing most of the sheet. This is to be expected as the ice thins and the sheet destabilizes.

Area has similar problems to extent though not as severe.

Extent is particularly bad as a tool, as it is prone to dramatically overestimating the ice. Compaction or expansion of the same ice due to currents and wind can rapidly change extent measures in either direction. Extent is also bad in that as the sheet shatters, extent as a measure tends to obscure the loss of ice. This can and has lead to horrible decision making advice suggesting that the demise of the ice is vastly farther off than it is.

All of these have difficulty with unknowns. As well as we understand the processes, we are still missing major parts. Each of the measures can be skewed by ponding, by changing ice character, changing ice color, changing ice salinity, snow cover, ground fog, and other factors.

More than this, though the data appears similar to a dataset involving a simple process with simple random variations in the data, neither of these is the case with the arctic ice. A huge array of factors complicate that. Certainly there is true randomness involved. But there is also quasi-random variation, autocorrelation, common mode actions and processes and other factors that make this not amenable to standard statistical tests. These are still useful, even though they are wrong. And we have to always bear in mind that they are wrong.

But in the end, there will be dominating factors. Thickness is one such in the case of the Arctic ice. As a result, volume projections will be those that show the earliest loss of the ice. And these will be the closest to correct. Liking a different data set does not make it dominant or controlling. Choosing to like a data set isn't a measure of its importance. It is rather a failing in understanding the problem.


Jim Hunt

Elisee -

1-3) Agreed

4) Surely sea ice area is a better metric when one is considering albedo feedback etc.?

5) I have to disagree with you on this one. There's all sorts of "processing" involved in turning "raw data right off the satellite" into the assorted SIE numbers. Check out the differences between the NASA Team, Bootstrap and ARTIST algorithms for example:


Regarding your final point, they are indeed. Check out this recent "retweet" by the 45th President of the good ol' U S of A for a prime example:


Jim Hunt

Doc et al.

You may be interested to learn that JAXA/ViSHOP extent has fallen (just!) below the 2007 minimum?


Elisee Reclus

Concerning Sam and Jim's comments --

Yes, there are many data metrics, each with its positive and negative aspects, they are all important and I do not particularly reject some and favor others. I do like Sea Ice Extent (SIE) because it is commonly used, it has been determined as particularly useful by experts in the field, and an easily referenced archive of it is available from one sensor and published in one source. There is also an unbroken set of these datasets from one sensor going back to the beginning of the satellite era. This makes discussing these observations less open to insinuendos of bias or fraud.

I worked in the reduction and interpretation of remotely sensed data for earth science applications for many years (Landsat, TM, HCMM, SeaSat, Multichannel Airborn Infrared Reflectance Radiometer); both in the development of image processing algorithms as well as the interpretation of those images for earth resource evaluation and monitoring. I concede I have been out of the field for twenty years now and may not be up-to-date on the latest developments, but I am well aware of the assumptions, processing and modelling that must be carried out to convert raw numerical pixel values from the satellite sensor into some sort of conclusion as to what is happening on the ground. Believe me, I am painfully aware of just how much subjective judgement, not to mention smoke and mirrors and hand-waving, is involved. However, although imagery from one sensor may vary greatly from that gathered by another, and different processing will also reveal very different images from the same data, a continued inspection of one consistent data set as seen by one sensor and processed in the same way has great value in detecting trends and communicating them to others. There are many different ways of squeezing information out of data, but when looking for long-term trends in a noisy signal, it is best to minimize as many of the variables as possible.

The earth climate engine is a complex and chaotic system and is only poorly understood. That's why we all come here to compare notes and see what is going on and what others with our interests are following. But when it comes to communicating conclusions we have arrived at to critics with honest skepticism, (not to mention villains with political, ideological or economic agendas) I believe the simplest and most straightforward display of data is the most effective.

I have chosen the NSIDC SIE time series graphic as my tool. In my opinion, its consistent and unambiguous depiction of the dramatic meltdown in the Arctic Basin over the last four decades is most convincing at describing what is happening and why.

Jim Hunt

JAXA/ViSHOP extent is now down to 4.03 million km². The 2016 minimum was 4.02.

In exciting news for the nerds amongst us I am reliably informed that at long last some more ice mass balance buoys are "awaiting deployment" across the Arctic Ocean, including four as part of the forthcoming MOSAiC expedition:


MOSAiC - Multidisciplinary drifting Observatory for the Study of Arctic Climate

It could be the largest-scale Arctic research expedition of all time: in September 2019 the German research icebreaker Polarstern will depart from Tromsø, Norway and, once it has reached its destination, will spend the next year drifting through the Arctic Ocean, trapped in the ice. A total of 600 people from 19 countries, who will be supplied by other icebreakers and aircraft, will participate in the expedition – and several times that number of researchers will subsequently use the data gathered to take climate and ecosystem research to the next level.

Doc Snow

After a working weekend having taken me out of the 'ice observation game' most inopportunely, it's exciting--in an ambivalent sort of way--to come back and find that 2019 has been flashing its late season legs while I was otherwise occupied, cracking off days of 20k and even a 40k decline. As Jim noted, the 2019 melt had surpassed 2007 as of 9/14.

But as of today's update (9/15), 2019 had edged past 2016's early minimum as well, posting a 4.01 million km2 extent!

So we have a new 2nd place lowest daily extent in the JAXA data.

The question then becomes, can 2019 still break below the 4 million milestone? 2007 was still at its minimum on 9/24 and 2018 at its minimum on 9/21. So there's precedent. But those are unusual trajectories. The fall equinox comes on the 23rd, give or take, and with it comes the seasonal sunset for the high Arctic.

Still, it remains anomalously warm across much of the Arctic basin. We'll see tomorrow whether that's enough to squeeze out another 10 or 20k drop.

Doc Snow

NB--Wegener had 2019 below 4 million km2 on the 13th already:


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