This year, the extent of sea ice in the Arctic has already plunged to its 2nd-lowest annual minimum on record. Here are the yearly minima, although this year’s value is provisional because it may well dip even lower:
A plot of annual average extent also clearly shows the decline, and includes data from throughout the year rather than just the annual minimum:
The figure for 2016 is the lowest on record, but the year isn’t done yet. If instead of averaging January-through-December we do September-through-August (to make the final year complete), we find that the most recent year is still the lowest on record:
Any way you look at it, Arctic sea ice is in decline. If you look at the entire year rather than just the annual minimum, the record year is this one.
So — you might think that climate deniers want to avoid the subject, right? After all, it makes their “case” look bad, very bad, so they wouldn’t want to bring attention to it, right?
Maybe they’re just not that smart.
The boys at WUWT have offered up this commentary, and the “spin” on the topic is obvious from the first sentence:
“Despite a lot of wailing and gnashing of teeth by Dr. Peter Wadhams, there’s still no joy in mudville for Arctic sea ice doomsters.”
Yes, there’s a guy who has been predicting the imminent if not near-immediate collapse of Arctic sea ice. He’s been wrong for a while, and seems to be still. This is used as an excuse to impugn scientists studying Arctic sea ice in general as being “sea ice doomsters.” Way to go!
Then there’s Christopher Booker, who seems to rejoice that Arctic sea ice isn’t going to set a new record for lowest annual minimum. The fact that it’s a record for lowest annual average, and more importantly that we’ve already lost nearly two million square kilometers of it because the trend is of dramatic decline, doesn’t seem to be what he want so focus on. He also kicks in a number of false claims at the end, to further discredit climate science.
But Booker, and WUWT, are making a big mistake by drawing attention to Arctic sea ice when they should be mum about the subject. You see, drawing attention to it makes people talk about it, some of them actually look at the data, some show the real data so you can see for yourself. And looking at the real data makes it plain: Arctic sea ice is declining seriously.
I’ll take the bait. I’ll post about Arctic sea ice. I’ll estimate the trend (spoiler alert: it’s decline). I’ll show the graphs. I want everybody to see — not just a “factoid” out of context and misinterpreted. Instead of shouting from the hilltops that “This year isn’t the lowest minimum on record!” I’ll show you the data, and point out that this year is only the 2nd-lowest annual minimum on record, but is the lowest annual average on record.
And as we do, the deniers will have another excuse to deny. But those who would be taken in by their sophistry weren’t going to be convinced anyway. Those who are already aware that man-made climate change is a serious threat, don’t need to be convinced by my graphs and charts.
It’s the vast majority who aren’t sure who really count … and here’s a clue for Watts and Booker: when they compare your statements with the real data, they won’t be buying what you’re selling.
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Open Mind 
The amazing thing is they keep doing this, even for instance after the pounding. Bastardi took on his Arctic ice forecast.
http://forum.arctic-sea-ice.net/index.php/topic,1493.4700.html
I don’t think it makes sense to bash the deniers because the “moderates” on sea ice loss are really not much better. I think it’s way late to declare emergeny, but emergency is what it is.
sea ice loss in winter?
http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0466.1?af=R
What I have seen when realists bring up the decline in Arctic sea ice, is that the deniers jump to the increase in Antarctic sea ice, as though this is some sort of mitigating balance. Nevermind that the land ice mass there is in decline, as it is in Greenland, and in glaciers all over the world.
Somehow, the sea in east Antarctica is supposed to compensate for all of that, That’s some kind of motivated reasoning (or deception if you like).
This year, though, they are rather quiet about the Antarctic. Guess why…
Thanks for another excellent Arctic analysis Tamino.
Mr. Watts has refused to print my clarifying comments on his most recent icy missive, but “Malice in Blunderland” has no such inhibitions. I hope that you and your readers might find the following at least moderately amusing?
“Dumb and Dumberer at the Blog of Fools”
It seems as though a certain Tony Heller and his many merry minions are already shitting themselves at the prospect of the plucky little yacht Northabout NOT getting “trapped in ice”. Hence we can provide this preliminary report on the astonishing ignorance of Tony and his faithful flock concerning all things Arctic.
Mike – As one of the so called “moderates” at the Arctic Sea Ice Forum to which you refer I wonder if I might enquire precisely what it is that you are objecting to?
Hi Jim,
I object to the way the moderates on sea ice loss pile on with personal attacks on the folks like Wadhams (the radicals on sea ice loss) or otherwise demean the radical view of sea ice loss instead of acknowledging that the alarm being raised by the radicals is useful and well-guided. Attacking folks who think the ice-free Arctic is imminent by arguing that it won’t happen until 2036 or 2045 or maybe by 2100 distracts attention from the fact that an ice-free Arctic is certain and imminent in a time frame that is disastrous for many species, including our own. I don’t hear moderates speaking up for the radicals on sea ice loss when the radicals are attacked and demeaned. I think the moderates get lost in the details of their scientific work and fail to embrace the radicals’ work as meaningful even if it turns out to be wrong by a decade or two.
And of course, as Aaron Lewis covered, the sea ice cover may be just an artifact now, the shards of a polar ice cap that is now gone for all practical purposes.
If you are late to the game, you are part of the problem, you might as well be a denier. Actually, the moderates who attack the radicals may be worse than the deniers because at the least the deniers have almost zero credibility now.
Hope I answered your question. Warm regards.
It’s the radicals who actually cause the major shifts in direction – they are the “advance guard” who bring stuff to everybodies attention. The moderates are the ones who quietly work away on the main body of the change, doing the bulk of the work. Each compliments the other. In an ideal world, you probably wouldn’t need radicals, but……….
I would like to see a graph of sea ice volume. The sea ice extent graphs are misleading because coverage of 15% or more is counted as coverage.
[Response: The extent graphs are not misleading; that’s a ridiculous idea. Extent can be measured more accurately than volume.]
And, of course, there are no comprehensive empirical measurements of ice volume because we lack comprehensive empirical measurements of ice thickness. Data sets like PIOMAS aren’t strictly empirical because thickness is mostly modeled (though available observations are used to constrain the models.)
However, there is sea ice ‘area’ data, which addresses the 15% concern. It may be more appropriate than extent to contemporary ice conditions, especially summer-fall ones.
@todaysguest
Here’s your graph of sea ice volume:
To which I’d add the time series graph, which is more comparable to Tamino’s above:
Is coverage of 15% meaningful?
[Response: Yes.]
15% is just a way of summarising a complex situation into a single number. Any summary necessarily throws away a lot of information. All sensible summaries show the same general conclusion, i.e. that the amount of ice is declining.
My long-form essay on sea ice:
http://hubpages.com/politics/A-Love-Story-And-A-Clearance-Sale
Among other things, it lays out the particulars of ‘extent’, ‘area’ and ‘volume’ measurements.
It’s still shocking to really think about, but the difference at seasonal ice minimum in volume terms is currently around 75-80%–that is, ice at minimum these days is about a fifth of what there used to be, back when the satellite record began in the winter of ’78-’79.
To claim that the Arctic Sea Ice is not gone, is to claim that you can serve tea in a smashed teacup.
We dropped AGW on the ice, and the ice broke into a thousand pieces. We still have some of the pieces of the ice, but they do not do what the cold, dry, strong, continuous ice did. Teacups and Arctic sea ice lose functionality when they are smashed.
The Arctic Sea ice as we knew it in 1900 or 1970, is just as “gone” as a smashed tea cup. Yes, there are still chips left, but most of its usefulness is gone. In a statistical study, it is important to choose the correct endpoint.
When studying the lifespan of teacups, do you measure to when the teacup breaks; or when the last shards and chips have passed through the midden, and into archeology collections? Today, the sea ice is broken chips and shards.
Hi. Can you explain what “extent anomaly” is? I don’t understand why you use “extent” for the first graph and “extent anomaly” for the other two.
“Extent anomaly” is the departure of the extent from some defined norm. This idea of ‘anomaly’ is encountered a lot in temperature time series, where the ‘defined norm’ is often the mean value during a specific period, say 30 years.
I’ll let Tamino speak for himself, if he wishes, on exactly why he chose the anomaly for the two graphs you speak of. But one result of the choice is that you get a bit more context, because the ‘zero’ value (often termed ‘baseline’) is a norm. (Hopefully a sensibly chosen one.)
This simply confirms that the northern hemisphere has warmed. It does not confirm what the cause of the warming is. Regardless of the cause we need to plan for it.
We do not know if there was more or less sea ice during the other warm periods over the last 4000 years.
[Response: Bullshit. See this.
And we do know what the cause of the warming is. You just don’t want to accept the truth.]
@Jay Colburn
“This simply confirms that the northern hemisphere has warmed. It does not confirm what the cause of the warming is. Regardless of the cause we need to plan for it.
We do not know if there was more or less sea ice during the other warm periods over the last 4000 years.”
Sure, we can suppress responsibility. Problem is, that is exactly the cause, that brought us here in the first place. So, if we go on suppressing responsibility, we can not SOLVE the CAUSE, right?! We can avoid our responsibility, we can suppress the truth, but we can never escape causality, that’s the beauty of reality.
Understanding uncertainties in sea ice extent should cause one to seriously consider whether the typical sea ice extent graphs *are* misleading, giving the impression that 2016 extent is significantly larger than 2012 extent. Deeper analysis may show the difference is not that large at all.
The 15% threshhold becomes very meaningful as the distribution of marginal ice zones increases. The standard deviation (σ) of the DMI ice concentration data is 14% from 10% to 95% concentration. At the typically used confidence interval of 95% we are then looking at uncertainties of closer to 30%. It’s instructive to note that the DMI “typical uncertainty values” figure 6 in the ATBD has an X-axis (ice concentration) that runs from -20% to 120%.
In high concentration regimes there is little chance of a grid cell not being counted correctly. As concentration decreases, especially as it gets lower than 30%, the chance of it being counted incorrectly increases.
What we have seen is an increase in the expanse of the marginal ice zones. This year saw low concentration areas up to and including the pole. And since there is no satellite coverage at the pole it is assumed to be 100%. That may have been a safe assumption a few decades ago – it is not true today and biases the result.
I would really like to see a time series of the distribution of concentration values before I’d be willing to make any comparison of current years with past years using sea ice extent. To my mind, current values are biased high.
Algorithm Theoretical Basis Document for the OSI SAF Global Reprocessed Sea Ice Concentration Product
[Response: I suspect you don’t really understand the meaning or consequences of uncertainty in concentration measurements.]
oneillsinwisconsin: What you would “like to see” is very much what professionals would “like to see”. They would “like to see” actual, not modeled, volume as well. Every scientist would “like to see” their subject as perfectly as possible. Astronomers would “like to see” stars close up too.
Why, pray tell, do you think they are not presently getting what you would “like to see”? Hint: Are you willing to fund the hundreds of millions–perhaps billions–it would take invent and to put in place instrumentation that could provide data you would “like to see”? Scientists have to work within the reality of their instruments.
BTW, there is clearly not 100% ice coverage at the North Pole. Here is a picture: https://twitter.com/ccg_gcc/status/769867469628596224
Please forgive the somewhat tongue in cheek tone of this article Tamino, but have you taken a close look at the 2016 remake of Santa’s secret summer swimming pool?
http://GreatWhiteCon.info/2016/09/santa-extends-his-secret-summer-swimming-pool/
Does that help make the point? Or not?
Can a denier who pretends to professional expertise but cannot demonstrate it BE embarrassed?
I see all you posters think the world started in 1979. Graphing a time series over such a limited time period simply distorts the reality. We do know one thing at least, the northwest passage has been open since at least 1906 so melting in summer is not unusual. Since research shows the whole arctic seems to have been ice free in summer from 8500-6500 BP and it was warmer than the present in 1000 AD while colder in 1625, the present ice numbers most likely are not average.
[Response: Bullshit the northwest passage has been open since 1906. That may be when Roald Amundsen completed the first passage, but it took him three years as he kept getting frozen in the ice. And your claims about sea ice coverage are likewise ridiculous.
Deniers just make up stuff. My opinion: you’re a denier.]
First, there is a difference between “enough open water that a tiny fishing boat (which is what Gjoa was) can painstakingly thread her way through” and “open.” By equating the two, you are deluding yourself.
And since you value history, you might consider the fact that the next ship to transit the NWP after Gjoa was the St. Roch. Again, a smallish vessel, and one purpose-built for Arctic navigation. Again, the first transit took three years, though a second attempt in 1944 finally made it in a single season:
Damn. Sorry for the busted ’em’ tag in HTML impairing readability.
Tamino writes: “I suspect you don’t really understand the meaning or consequences of uncertainty in concentration measurements.”
Anything’s possible, but the ATBD is pretty clear. What isn’t clear is the distribution of concentration values. If one assumes that the distributions are all symmetrical and are free from bias, then there’s really no problem; those that are counted high will be cancelled by those counted low. That’s a pretty big assumption.
As for the ‘pole hole’ — NSIDC says: Sea Ice Index Version 2
“<B<Relevance of the Pole Hole to Ice Extent and Ice Area Values
Due to orbit inclination, the satellite-borne instruments that collect the brightness temperature data that go into creating the Sea Ice Index do not image a circular area over the North and South poles. This area is referred to as the pole hole. With three different generations of instruments, there are three different pole hole sizes through the time series. See Table 6.
To account for these holes in the spatial coverage of the data, three pole hole masks are used, one mask per instrument. They are termed masks because they are overlaid onto the input GSFC and NRTSI ice concentration data by the Sea Ice Index processing code prior to calculating ice extent and area. The holes are significant because, in calculating Northern Hemisphere ice extent, it is assumed that the entire region under the pole hole is covered by ice at greater than 15 percent concentration.“
And since 15% is the threshhold, the entire pole hole is considered covered by ice. So, the pole hole alone biases the measurements. In the past it was safe to assume > 15% SIC; today, not so much. This means that in comparison to the past today’s measurements are biased high.
You may cut the following or not – I really don’t care.
Glib assumptions on the understanding – or lack of understanding – of others are not often appreciated. I was seriously considering checking to see whether my boss would pay you for a couple hours work reviewing an uncertainty budget and some of the Monte Carlo simulations I had used to derive measurement uncertainties. I suspect the work could be done rather quickly in R, but I’m not proficient in R and learned just enough to get the statistics I needed. I am confident in the results and — even though there’s no accredited US lab for the measurement (i.e., we will be the first) — I do have results from a European lab with which I can compare. If anything, I think I’ve been conservative in the statement of measurement uncertainties. I’ll just pass my work on to them for review to see if they spot anything untoward.
[Response: Bold assertions by someone who “learned just enough to get the statistics I needed” are not often appreciated.]
Tamino, you’re being rather rude. He doesn’t appear to be a denier (correct me if I’m wrong)—even if he was you should still stay (relatively) polite—and is not saying that sea ice isn’t declining, so your responses have not been appropriate.
He’s just pointing out that there are some problems, either potential or already known, with sea ice data that might bias extent high now that the ice pack is becoming generally sparser, with larger marginal areas. That isn’t anything new; it’s something that I’ve seen many people, including die hard arctic sea ice enthusiasts over at the ASIF, saying for at least a few years now. Even arctic researchers would acknowledge that the data has flaws (monitoring is of course limited), which is why they want better instrumentation for better data. I’m also pretty sure that when he said, “learned just enough to get the statistics I needed”, he’s talking about learning enough R, not the statistics itself. His profile says he’s a metrologist, so he likely has some expertise and experience when it comes to measurement, rather than being incompetent like how you were treating him.
If you disagree with his position, it would be a far better approach to voice your reasons for your disagreement, rather than simply resorting to ad hominem attacks. Especially since he seems to want to have some actual discussion, and would likely appreciate hearing a serious reply from you about your own understanding of what he’s bringing up. Your replies to his two comments on this thread so far are just burning bridges, and come across as reactionary, overly defensive, and unnecessarily dismissive.
Perhaps you mistakenly thought that he was a denier and was trying to make reasons for ignoring sea ice decline, but he he does not appear to be at all. Letting yourself be controlled by a hair trigger reaction of rudeness—that’s how it comes across—is unbecoming and beneath someone of your intelligence and expertise.
Don’t sink to the same level as deniers by attacking people making a serious point, rather than responding to the position if you disagree with it. Trust me, I understand that reaction; there are many times that I just want to wring out some truly astoundingly stubborn, stupid, ignorant, and incompetent deniers, but we need to exercise restraint. By directly attacking people who are deniers we just push them away and further reduce the chances of them ever learning, since we enforce an “us vs. them” regime. In the case of people repeating the same tired bullcrap and refusing to listen to attempts to have a discussion and inform them, dismissal is appropriate, though it should still be kept civil. But people who want to have an intelligent discussion shouldn’t be given the same response even if you disagree with them, which was the case here, thus this is a case of an inappropriate response on your end.
I hope you two can clear this up since I actually would really like to see further discussion of the topic of problems with sea ice data and instrumentation, and the implications as ice concentrations and extent decline. I at least would find it interesting and informative.
I made this post far too long. Oops. Guess I once again fell into my tendency to over-explain everything.
Michael – thank you. I’m just as guilty of having a ‘hair trigger’ and when something bleeding obvious (to me) is dismissed out of hand I’ve lost the ability to display any tact — not that I ever had much to begin with.
How does a potential bias in the amount of arctic ice which can only provide an OVERestimate of sea ice overturn the clear evidence of a DECREASE? Be specific.
@jgnfld – It doesn’t! Who said it did?
“Compaction” is low this year. 2016 area is much closer to the 2012 figure than extent.
jgnfld – I wrote: “This means that in comparison to the past today’s measurements are biased high.”
Now, why you think I’m a denier is beyond me. My point was precisely what you are now parroting — that the pole hole leads to an overestimation bias based on ice conditions today vs 1979.
Based on this Tamino said I didn’t know what I was talking about. Apparently you don’t know what you’re talking about either since you’re now making the same point I previously made. The ‘pole hole’ biases measurements high today compared to yesteryear.
[Response: No, my statement was based on your other rambling.]
Yes, I made the bold assertion that the way the ‘pole hole’ is treated biases results high. Other than being dismissive, have you rebutted that statement?
No.
I’m an amateur with some skills, but not enough, and feel my boots and all, fools rush in commentary should be presented with humility. It shocks me sometimes that guests at a blog feel so entitled with their host. I can sympathize with impatience with commenters who present themselves as experts in the face of a real expert. However, we don’t need just people who respect and seek expertise, but everyone, to step aside from the quibbling which is mostly an excuse for inaction and delay. That is dangerous. Some may be more patient that others, and Tamino knows his stuff, so patience should be a two-way street.
With regard to ice, for more expert questioning and detail, I’d go over to neven’s where any and all honest questions are debated at length from a wide range of seekers after understanding and knowledge, with scads of visual aids and other references, particularly in the forum.
http://neven1.typepad.com/
A picture is worth a thousand words? Here’s two. Different views of <100% concentration sea ice inside the SSMIS "Pole Hole":
But what’s the grid size. Would any of that show up as less than 15% ice covered?
It would certainly show up as <100% though Greg! This is AMSR2 concentration on a 3.125 km grid from the University of Hamburg. Note the “Pole Hole”:
That vast area of fractured sea ice doesn’t show up as <100% on the NSIDC's 25 km grid for their Sea Ice Index though, which I believe is the point a number of commenters above are trying to make?
With a bit of code tweaking I could probably come up with a high res AMSR2 15% threshold extent map for you. Watch this space. Possibly for quite a while!
Somewhat belatedly, here’s high resolution AMSR2 “emprickable evidence” from August 31st:
http://greatwhitecon.info/wp-content/uploads/2016/09/20160831-15-ext.jpg
More ice than in 2012, therefore ice has increased from it’s historic low, therefore global warming isn’t happening and the new little ice age is on it’s way. Unassailable logic, surely; I’m sure Australia’s (our very own, sorry to say) Senator Roberts would call that emprickable evidence.
“… emprickable evidence…”
Something Senator Roberts should know about, surely? ;-)