Wosis then? Is it the sea ice? Ah, no. Someone else wants in on the limelight: "Parts of Arctic Siberia are releasing ten times more carbon into the atmosphere than previously thought, a University of Manchester scientist and an international team of researchers have found."
Its the usual stuff:
much more greenhouse gas is being released into the atmosphere than previously calculated, from and ancient an large carbon pool held in a permafrost along the 7,000 km desolate coast of northernmost Siberian Arctic – dramatically increasing global warming. As the temperature climbs carbon, stored in vast ice walls along this Arctic coast called Yedoma, covering about one million km2 (four times the area of the UK), is pouring into the Arctic Ocean in one of the world’s most remote and desolate regions. This region is experiencing twice the global average of climate warming. While satellite images reveal thousands of kilometers of milky-cloudy waters along the Arctic coast, suggesting a massive influx of material, the Yedoma has remained understudied largely due to the region’s inaccessibility. By studying the thaw-eroding slopes of a disappearing island, the team found that the tens-of-thousands year old coastal Yedoma carbon is rapidly converted to CO2 and methane, even before being washed into the sea
and so on. It is honest enough to say quietly that the present rate of carbon release from the NE Siberian coast is not substantially affecting the CO2 levels in the global atmosphere yet - but then how can you possibly reconcile that with the headline? Or indeed the following text the scale of the release of both CO2 and methane into the atmosphere will have a huge effect. This will have consequences for the temperatures all over the world. There are various nutters pushing the "methane emergency" line. And although that in itself doesn't discredit more serious people, the serious people need to talk sense and not just grab headlines, if they want to be taken seriously.
None of which says anything about the quality of the science, which sits quietly paywalled by Nurture. Its quite likely a valuable, if minor, contribution to our knowledge of carbon fluxes in the Arctic. It just doesn't deserve the headlines it is offering.
And speaking of, errm, overenthusiasm, don't get me started on Wadhams The entire ice cover is now on the point of collapse... It is truly the case that it will be all gone by 2015. No, it won't be.
I've been drawing simple bar graphs that track the minimum ice extent, area or volume for each year to date. With the PIOMAS August update (through 8/25) the results for ice volume are striking:
was prof. Wadhams your boss?
[No. He was a SPRI, I was at BAS. We worked together a little bit -W]
Ted Scambos of NSIDC defined "ice-free arctic" as with 1 mil km2 of ice... and that, according to him should happen around 2030... but it seems too slow to me, according to PIOMASS (?)... whatever, global CO2 is still on the rise, despite economic contraction in USA, Europe and Japan, so given that arctic ice is doomed anyway (be it in 2030), will the cascading effects continue?
[I have money on no collapse, of course -W]
BTW, Paul Beckwith (still) stands with his prediction that current rate of arctic melting will continue till around end of september, effectively reducing arctic ice to... close to zero... :-)
[Don't know him. Got a link? -W]
And here is the link on Ted's interview:
Ok, me again, pointing to Stuart Staniford take in arctic ice volume: http://earlywarn.blogspot.cz/2012/08/arctic-sea-ice-volume.html
William, here is link on Paul Beckwith latest presentation:
[He really does seem to say that he expects it all gone by the end of this season. I'm 99.9% sure he is wrong, which is fine, because we'll find out in less than a month -W]
" And although that in itself doesn’t discredit more serious people, the serious people need to talk sense and not just grab headlines, if they want to be taken seriously."
This is a difficult subject to discuss because the implications are dire, but the knowledge base is weak. Of course a weak knowledge base doesn't mean there is or isn't something to worry about. Media bounces back and forth between silent and confused. This is something that should be fixed. Do you have a link to what you think is serious? I would say what Archer said a while back - short term not a problem known yet, but long tail effects a huge problem. Would you agree?
[I think the paper in Nature is serious. I'm sure the researchers themselves are serious. But they need to rein in their press people, and they need to make sure that they themselves aren't seeking cheap PR.
As to the long term effects of permafrost etc carbon release from the Arctic: my impression was that it was unlikely to be a first-order effect (and I thought that was what Archer had said, too) -W]
"The entire ice cover is now on the point of collapse… It is truly the case that it will be all gone by 2015. No, it won’t be."
Climate models predictions of sea ice look a little optimistic, to say the least. Starting with the great melt in 2007, then lack of recovery and continuing decline such as this year. The mainstream climate models sea ice, as far as I know, do not and would not show a decline like this until much later. Yet I'm just a part time reader of papers. Am I incorrect?
Based on the rate of decline, fall sea ice might be mostly gone by 2015, but I'm not a fan of "curve fitting science". Are there any updated models that will show a decline like we have seen from 2007-2012? If so, what do they predict for the ice out date?
[See Gavin's comment later down. I'm hoping RC will do a post on this, since I'm now out of touch with the latest modelling. You're right that AR4 type models don't really show the observed decline. OTOH only this year has it really become clear that 2007 wasn't a fluke, and even that still has some chance of being premature -W]
Clearly it's a serious issue. But in the absence of solid means of forecasting, the over-confident statements from Wadhams and Beckwith - based on nothing more than extrapolation that has no physical basis (or verification) - is foolish. I agree with William that they are very likely to be shown to be wildly erroneous, and then everyone else is going to spend the next decade being tarred with their brush.
The models in CMIP5 are better than they were in CMIP3 - at least what is happening is now within the model spread, but we still don't have a good way of honing the projections to produce a confident estimate (models that do equally well for today, still have big divergences on the summer ice free date).
>>Wadham's "It is truly the case that it will be all gone by 2015."
>William "No, it won’t be."
I agree that "***will*** be all gone" is wrong. But is "No, it won’t be" similarly wrongly certain (assuming we are talking of almost all gone for just a few days)?
(I accept there is bound to be some sheltered fjords with some sea ice, perhaps some clinging to remains of ice shelves and a few other random bits.)
Volume per PIOMAS down to 3.599 at 26 Aug and likely to lose say 0.35 as last year which is low for the time of year. That gets us down to a minimum of 3.25.
Last 10 years mimimum to minimum have changed:
Year, 1yr chg, 3 yr chg
2004-5, -0.7, -1.6
2005-6, -0.2, -1.2
2006-7, -2.5, -3.4
2007-8, +0.6, -2.1
2008-9, -0.2, -2.1
2009-10, -2.5, -2.1
2010-11, -0.4, -3.1
2011-12, -0.75, -3.65
Only 2 out of 8 of those 3 year periods show a decline of more than the 3.25 projected to be left this year. However another one is close and there appears to be an upward trend. Last 6 of the 8 3 year periods have all shown losses of over 2k km^3. This seems to suggest to me that we are likely to get down to 1k Km^3 and there is the possibility of albedo feedback continuing to be more important than the negative insulation effect which could practically wipe out that remaining 1k km^3.
So I don't think you should be so certain that it won't be all gone.
[I have $10k on If both NSIDC and IARC-JAXA September 2016 monthly average sea ice extent report are above 4.80 million km^2, RD pays WMC US$ 10,000. If both are below 3.10 million km^2, WMC pays RD US$ 10,000. In all other cases the bet is null and void - http://scienceblogs.com/stoat/2011/06/26/betting-on-sea-ice-10000/. How much more certain would you like me to be? Mind you, given this year... -W]
William and Gavin,
what are the physical reasons for (significant) slow-down of arctic ice volumetric melting? Clearly, it has to happen, if the ice should melt significantly later than in 2020 or so...
[Do you mean slow-down, or failure to continue to follow the quadratic decline? Since there is no physical mechanism for the latter, what is the reason for expecting it to continue? -W]
Quess we'll panic when we have to panic...sorry, quess we should notice it all when we have to notice it.
"The models in CMIP5 are better than they were in CMIP3 – at least what is happening is now within the model spread, but we still don’t have a good way of honing the projections to produce a confident estimate (models that do equally well for today, still have big divergences on the summer ice free date)." (Gavin)
Would you please provide more information on the range of divergences? For example, do any runs of any of these models show a nearly ice free late summer anytime in the next decade?
In Stroeve's plot it appears a couple of model realisations predict "ice-free" conditions in the late-2010s. However, both (CanESM and GISS E2-R) begin at a much lower absolute extent than observed so I'm not sure how this should be interpreted.
One MIROC realisation produces some "ice-free" years in the early-2020s, but it looks like that happens with an abrupt drop of ~4million sq. km over about 3 years, followed by an equally rapid increase of 3 million sq. km.
The Massonnet paper plots 5-year means so the persistent trends are clearer. Models start being regularly "ice-free" in the 2030s.
People are getting ahead of themselves claiming the ice is going to disappear in a few years. There is too much "excitement".
Since 2000 CT minimum has only declined by about a third. It's entirely plausible, perhaps even probable, that it will take another 20 years or more to reach zero. That's short enough to be meaningful but people still try and push out the idea that it'll be gone in just a few years. Yes it *could* but if it doesn't and the ice is still around in 2020 it's going to make everyone look like a bunch of (dare I say it) alarmists.
While I am sure the deniers will have bigger problems by then with all their "global cooling" predictions failing, it still makes no sense to give them a hand by setting the "alarmist" target so low. Golden rule: if the ice trends anywhere above your target the deniers will crow about it. They are only in a bind at the moment because the ice trends are below a lot of past predictions and so they can't play that card.
Thank you, and I should have thought of that before asking.
Beckwith has an update: https://docs.google.com/file/d/0ByLujhsHsxP7VTlsczIyalpjNDQ/edit
In a FB post pointing to it, he mentions that ice coming from Greenland is replenishing the Arctic supply.
Beckwith's claim that Greenland ice is a significant source for the Arctic sea ice isn't reasonable. Ice from glaciers is odd shaped chunks ranging in size from tiny to mountains of ice, and sea ice is flat sheets of ice, with pressure ridges and such.
Not only that, look at MODIS image from today, good section of Northern Greenland is at the bottom of image, cloud free:
No sign at all of major ice output from Greenland.
"Do you mean slow-down, or failure to continue to follow the quadratic decline? Since there is no physical mechanism for the latter, what is the reason for expecting it to continue?"
Then find the mechanism, because it is happening. The decline of Arctic sea ice is so very clearly non linear. Just how many data points do you need to see?
As the melting continues the freeze up has already begun, so we will not see zero sea ice this year. And perhaps that polar core will remain, all be it vastly reduced, for some years to come. Perhaps a Gomtrez fit will end up better.
But as for the bet, start saving.
What is a "Gomtrez fit"? Web search doesn't find it.
So I cannot spell
The slow start to the loss of ice, quick in the middle, and slow finish, if indeed it is a slow finish.
We don't have a physical mechanism to describe how the decline might continue on its present course, but on the other hand we also don't have a physical mechanism to describe why the ice is apparently vanishing far ahead of schedule. The very best effort to model the physics of the situation is obviously failing.
So we're all guessing what's going to happen, in the very short term. My meta bet is that William is going to just barely keep his money, based on events since 2007. Up, down, up, down, but down is 1.x up, where x !=0.
It is disconcerting that the global albedo losss attending the latest loss of Arctic ice approximates the gain that might be had by painting all the roofs in the hemisphere white.
Yeah, but if you paint all the old roofs white, then you get condensation on the undersides of those that aren't perfectly insulated with a good vapor barrier, and the roofs rot out.
"Then find the mechanism, because it is happening. The decline of Arctic sea ice is so very clearly non linear."
I found this paper to be interesting, and you might as well.
[Yes it is. Worth posting on I think -W]
Gavin wrote "the over-confident statements from Wadhams and Beckwith – based on nothing more than extrapolation that has no physical basis (or verification) – is foolish."
I would accept that there isn't a satisfactory physical basis worthy of being published but to suggest no physical basis at all seems to be overdoing it.
It isn't hard to review the literature and gain an impression that the major feedbacks altering the heat budget are a positive albedo feedback in summer and a negative insulation feedback in winter. From phyiscal reasoning, we don't know which is going to turn out to be a stronger feedback as they both seem likely to strengthen as ice retreats earlier and as the ice gets thinner. However we can look at the graphs and gain the impression that so far the acceleration seems to be downwards. While there is no sign of this acceleration slowing down yet, this does not meant that it won't slow down. Given the shapes the models show, I think it is sensible to expect a slow down at some point. However, not only do I not see a lot of time available for this to come to the rescue and prevent an ice free few days occurring within the next few years but it also has to arrive suddenly with a surprisingly strong effect. I therefore prefer gompertz fit to an exponential fit.
I think I can see limits to the negative insulation feedback which mean this isn't going to save us from an ice free few days in next few years. Later start can mean we rapidly catch up in thickness but this is not going to lead to thicker maximum thickness. While that may mean there is little reduction in thickness in the centre of the pack, around the edges a later start to freeze season is likely to make more difference. There could be other feedbacks that also assist the insulation feedback. However, GHG continue to rise and so does temperature of incoming Atlantic water.
Not publishable but it is within the relms of what can sensibly be bet upon. I have 4 bets with William.
Saying we have to stick with 2040-2100 per model which involves ingoring the bias in models rather than attempting to correct for the bias seems extraordinarily bizarre to me.
Using an exponential fit without considering a slow down is also bizarre but if we are not contrained to just what is publishable (as for instance in betting), I think we can do better than these two bizarre extremes.
It would be helpful to have an Arctic Ocean surface temperature anamoly product.
"Saying we have to stick with 2040-2100 per model which involves ingoring the bias in models rather than attempting to correct for the bias seems extraordinarily bizarre to me."
It seems to me that there might be ways to reduce the amount of bias in the models. Perhaps data assimilation, in several different ways?
[That requires a different way to run the models, which I think people would not be keen on, except for special purposes -W]
From over on Tamino's, UAH gives 0.53 degrees Celcius per decade for the Arctic ocean.
>"It seems to me that there might be ways to reduce the amount of bias in the models. Perhaps data assimilation, in several different ways?"
Yes there are probably several ways. PIOMAS is of course already doing data assimilation but Dr Schweiger seems to have rejected extrapolations of PIOMAS data. I haven't seen what PIOMAS does into the future without assimilation; that would be interesting to see.
Long extrapolations are obviously dodgy. But there has to be some short period for which extrapolations are as good if not better than clearly biased models. When that short period includes the extrapolations either getting to a few ice free days or within natural variability thereof then it is time to say: No, we must not stick with model projections of 2040 to 2100.
That short period may well be less than three years and we may not quite be at that point yet, but I suggest we are getting very close.
"Long extrapolations are obviously dodgy"
Short extrapolations are obviously dodgy. Model output varies a lot between runs, and if we could rerun climate in the real world I suspect there would be a lot of variation between experimental runs. For example on model output variation, if you look at "Massonnet et al. (submitted)" figure 1b MRI-CGCM3 curve, this model run is somewhat similar to the historical record from 1980, including a rapid drop to just below 4 x10^6 km^2 at about 2010 (note that this is a five year running mean). This model run then bounces back up to about 5.5x10^6 km^2, and finally reaches ice out in roughly 2050. I see no strong reason to call this model 'clearly biased' based on past history. It is a bit below the historical record, so if anything it might be biased a bit to lower sea ice extent. Do you have a reason to think that this model is not a reasonable estimation of reality? I see no reason why an extrapolation based on the recent history of the historical record will be any more accurate than this specific model run. Do you? An extrapolation of the first 30 years of this model run might lead to a projected ice out before 2020, but the model does not follow the extrapolation, and if this model run is at least a fair to middling representation of reality, then it appears to me that the same is likely to true of reality. In other words, I think that reality isn't more likely to follow an extrapolation, even a short one, than a specific model run, as long as the model is at least fair quality.
>"I see no reason why an extrapolation based on the recent history of the historical record will be any more accurate than this specific model run. Do you?"
Are you serious? Do you want to bet on whether the average of NSIDC September extent for 2013, 2014, and 2015 will be nearer to the values that model gives for those three years or to a gompertz extrapolation of historic extent measurements?
You continue to impress this "skeptic" with your skepticism.
At what point would you concede that anthropogenic CO2 wasn't worth worrying about?
If there is no data point that would convince you, what has made you certain of the need to constrain greenhouse gas emissions?
[I'm not saying that at all. I'm trying to convince responsible people to behave responsibly and not let their PR folk speak rubbish and pollute the world with nonsense. GW itself remains a serious problem that needs to be treated seriously. And the way to do that (as I said somewhere recently) is to start from the IPCC science summary, and not waste our time talking about the nutters. And then impose a carbon tax -W]
At what point would you concede that anthropogenic CO2 wasn’t worth worrying about?
Heh. Lance has been denying AGW on ScienceBlogs for at least five years. He still thinks it's a conspiracy led by Al Gore. Nothing's ever going to convince him that anthropogenic CO2 is worth worrying about, but he still calls himself a skeptic. DFTT.
"Do you want to bet on..."
No, but I might bet on something more subtle. Give me a bit to collect all I need.
gavin will never answer the question whether the models predict any ice-free summer periods in the next 10 years since - of course - he is not willing to take any risks to his reputation
[Gavin takes many risks to his reputation. What you don't like is that those risks pan out for him. You're not even prepared to risk you full name whilst criticising others, which is cowardly -W]
Model outputs are what they are, and have been widely documented. I can't see how simply reporting on model behaviour would affect Gavin's reputation in any way.
If you actually want to know, there are at least two links in this thread which contain plots of what various models predict for future September Arctic sea ice extent.
Phil Hays writes: Short extrapolations are obviously dodgy. [...] An extrapolation of the first 30 years of this model run might lead to a projected ice out before 2020, but the model does not follow the extrapolation, and if this model run is at least a fair to middling representation of reality, then it appears to me that the same is likely to true of reality. In other words, I think that reality isn’t more likely to follow an extrapolation, even a short one, than a specific model run, as long as the model is at least fair quality.
OK, you're making an argument that one (carefully selected) model run might provide "at least a fair to middling representation of reality". So its short-term predictions might be expected to be reasonably close to reality, at least in comparison to the many other model runs that don't do a good job of replicating the observed sea ice trend.
But nothing in there gives a basis for suggesting that that particular model run, or any model run, would be significantly less "dodgy" than simple extrapolation over the short term (say, the next couple of years). You assert that "short term extrapolations are dodgy", but don't explain why.
Short-term extrapolations are based on the assumption of persistence, the idea that current and recent conditions will generally tend to persist at least a short while into the future. So far, that's generally been the case -- if you use data from years [X-1 ... X-10] you can do a reasonable job of predicting sea ice extent in year X.
So why do you say that "short extrapolations are obviously dodgy?" We all live our daily lives based on short extrapolations!
crandles writes: Long extrapolations are obviously dodgy. But there has to be some short period for which extrapolations are as good if not better than clearly biased models. When that short period includes the extrapolations either getting to a few ice free days or within natural variability thereof then it is time to say: No, we must not stick with model projections of 2040 to 2100.
That short period may well be less than three years and we may not quite be at that point yet, but I suggest we are getting very close.
Yes, that seems exactly right to me.
It's always humbling to realize that what I wrote wasn't even close what I meant to write.
Example: “short extrapolations are obviously dodgy” should have perhaps been written as “an extrapolation of a complex system, based on a short history, can be misleading, even for a short amount of time". Or something close to that.
I'm bothered by the extrapolations of Arctic sea ice extent and/or volume for the reason that I think that the system is far more complex than can be predicted by a simple extrapolation given the historical data on this system.
So what about Arctic sea ice? There is a rough record of extent going back in time for hundreds of years based on ships logs and on shore based observations, later based on aircraft observations, and more recently on satellite observations. The earlier parts of this record seems to be far too rough to use for realistic extrapolation. What seems to be mostly used is the 1979 to current satellite record, which is of much better quality.
So is the sea ice simple? The past record doesn't look that simple, as there is a lot of variation, and the amount of variation has also varied. Models of sea ice seem to also have large amounts of variation. Expert opinion (of which my opinion is not a member of) also seems support the idea that sea ice isn't a simple system.
So Arctic sea ice has both a short record, and reasons to suspect complex behavior. This leads me to suspect that a simple extrapolation is likely to be wrong. How this plays out isn't something I have much of an opinion on. It seems to me that both a much longer and a much shorter time to "sea ice out" (extent 1 million km^2) might happen than what the extrapolation predicts. Also the behavior near the time of sea ice out might be rather different than anything seen before. All of these possibilities are not reflected in an extrapolation.
@[Incivility redacted - W] connolley: i can assure you that your sorrowful mimic expressed by your face on the photo on top of this page, most probably attributable to your basic fearful and alarmistic co2 mood, should brightening up when i inform you that the extent of arctic sea ice melting in completely irrelevant regarding any meaningful sea level rise, as the arctic sea ice is already swimming in the water and melting it competely does not even give you a minimum of hope for sea level rise of a fraction of one millimeter. this must be a big disappointment for climate alarmists like youm gavin and paul.
you should rather look at antarcticta where there were extremely low temperature recordings this year and even from there there was zero contribution of ice melting resulting to any lea level rise. again a huge defeat for you and the alarmistic climate church of al gore, jim hansen, gavin, kevin and michael mann, the hockeystick inventor.
[That was a bit incoherent; but I've been travelling, so got a slow response, sorry.
As for the pic, its taken while I was climbing.
As for the sea ice, you're multiply wrong. Firstly the link between sea ice retreat and SLR is via albedo feedback, not the more direct ice melt. Secondly, "does not even give you a minimum of hope for sea level rise of a fraction of one millimeter" is wrong. RMG will patiently explain this to you at http://moregrumbinescience.blogspot.co.uk/2009/04/ice-and-sea-level.html.
As for Antarctica, its warming there (as we all know) and I'm not aware of any very cold readings, other than the usual. Do provide references if you have any. And of course, as we know, the Pine Island glacier stuff shows ice melting in Antarctica and contributing to SLR.
I'm vaguely curious as to whether your being multiply wrong will affect your views at all, or if you're impervious to facts -W]
Kai is a poe, yes?
marco, also for you as a layperson, i officially inform you that your ridiculous belief on catastrophic flooding as a consequence of non-existent sea level rise is competely unsubstantiated. you just can give up this nonsense and do more meaningful things in your future life than advocating climate halluzinations. i wish you a quick recovery from your numerous climatological misbeliefs
Kai, I never mentioned anything about "catastrophic flooding", nor has anyone else on this thread. That sea level rise is supposedly non-existent...well, I guess you have to believe in a big conspiracy of all those people trying to measure changes in sea levels - and actually reporting it rises.
And does this church include some of its first members? People like Gilbert Plass, Roger Revelle, Hans Suesse, Suyotoro Manabe? Wetherald? Bolin?, Keeling? Does it include the scientists who wrote the first report on the risk of Climate Change - in 1965. President Johnson made a speech to Congress on the subject.
Does it include the various Commandant's of the USAF GeoPhysical Laboratory that lead the research program into the EM radiation absorbing/emitting properties of a wide range of atmospheric gases in the atmosphere, including CO2. In the1 950's & 60's!. What about the commanders of US Nuclear submarines reporting back on changes in Arctic Ice thickness?
The nasa engineers building and launching satellites measuring atmospheric temperature changes, rising Tropopause, increased water vapour content. The Euroopean engineers that designed the GRACE satellites that are directly measuring the loss of Ice mass in the Arctic, Antarctica and glaciers globally - 500 billion tonnes a year? The research teams from several different countries that are measuring increases in ocean heat content, thining of the shells of pteropods in the ocean due to acidification, increases in the temperature of various major ocean currents, reductions in the speed of the Polar Jet Stream? The geologists reporting on the geological evidence for past warm periods, past major acidification events, etc. Or the geologists that can tell us how much higher sea levels were in the past, at the peak of the previous InterGlacial period, the Eemian. High enough that Scandinavia was turned into an island.
Are these folks part of that church too? Particularly some of the names at the beginning of the list who have to be classified as past members since they are dead.
That is one damn big church kai!
There are a few reasons why we might consider the conclusions from the models as perhaps unreliable at predicting the timing of the eventual demise of the Arctic Sea ice. And I am not trying to attack the models or modellers here. It is just that they are dealing with a complex subject, and the science takes time to advance.And it is just possible that they may well be overtaken by events before the science gets far enough advanced.
Unlike other areas of climate modelling, Arctic ice modelling has to actually model the vaniishing of the system being modelled. Atmospheric or Ocean modellers for example don't have to include within their models end stages where the atmosphere or the oceans vanish.
Let me state first, I don't know what the ice models actually model. So I am speaking generally about factors that may or may not impact on the quality of what the models can do, but I don't know for certain what they do.
The problem for ice modellers is that models that may be 'skillful' at modelling the physics producing the general trends for the ice over longer time scales may not necessarily have the same skill at modelling the physics of the terminal phase. Broadly speaking one would expect to see thermodynamic and fluid-mechanics type factors being the major components in any model of Arctic ice covering most of the past record - Air and water temperatures and stratification, wind speed & direction, water salinity profiles, ice thickness, ice thermal conductivity etc.
Equally they would be likely be modelling broad trends in these factors over time, with an implicit assumption that there is a natural variability in these factors which cannot be directly modelled, but the models can estimate the likely range of this variability.
What is harder to model, but may be a significant factor during the terminal phase of the ice decline is that some of these natural variability factors may begin to have disproportionate impacts in the terminal phase.
Some examples to highlight what I mean, and also point to some of the feedback factors that may well continue the current rate of decline.
- This year an eye witness account described a large ice flow, around 10 km^2. A series of waves associated with the large cyclone in early August passed under the flow and after they had passed it had all been broken up into pieces of around 100 m^2 each. The Ice this year has been described as a 'giant slushy'. If the ice had been much thicker it may not have broken up as much, or even the presence of lots of thick ice may even have supressed wave formation. But no longer.
- Storms such as the one this year smash the ice up a lot. They also overturn flows and wash salty sea water over the top of a flow. This saltier water has a lower freezing point so conversely accelerates melting above.
- Major storm activity turns the waters below over. During the melt season the sea water under the ice actually has an interesting vertical structure. Immediately below the ice it is fresher and colder. Further down it is more saline and a bit warmer. This vertical gradient of colder water over warmer water is possible because the density difference due to the salinity gradient counter-balances the buoyancy forces due to warmer water below cooler water; Use of controlled salinity gradients to supress convection was being trialled in the 1980's as a way of building 'solar' ponds that could store heat at the bottom of the pond without it rising. Hopefully ice models would include such a 'freshwater lens' effect. However, can they include the effect of individual storms that disrupt the lens, mixing warmer & saltier water that is further from its freezing point up to the underside of the ice, accelerating melt?
- If the ice is more broken up and thus potentially mobile, how much greater are the impacts of annual variations in weather patterns in moving ice over long distances. And particularly out of the Arctic. Ice can be lost either by melting in situ, or by flowing out of the Arctic, primarily through the Fram strait. How much the 'Fram Express' operates each year depends substantially on prevailing weather patterns that year. This year was a relatively low year for ice movement out of the Fram but still we broke every record.
- How well do ice models capture freshwater flows into the Arctic from rivers, and their geopgraphical impacts. In particularly the giant Ob river system. Freshwater from the land that is only a few degrees C is still substantially warmer compared to salty water just above freezing at -1 C. Some of the melt patterns betwen 80 & 87 North above the Laptev Sea this year look suspiciously like an influence from fresh water flows.
- Generally, as more of the Arctic melts earlier, more of that open water is able to warm by absorbing sunlight for longer. As the refreeze starts this accumulated heat has to be removed again before the freeze can start in earnest. So if this delays the refreeze, the total thickness that can accumulate before next summer is reduced. So it melts out earlier, allowing more time for sunlight the next year and so on - a classic positive feedback.
One final observation. The general shape of any curve tracking Area/Extent over time that one would expect to see based on the fundamental physics of all this is a moderate although perhaps increasing decline, with a precipitous decline at the end. This can be described simply with some basic physics. Arctic Sea Ice is essentially large flat sheets, some meters thick. Over the course of the melt/freeze cycle, these sheets thin and thicken, substantially because of that happens at the bottom surface of the ice, then to a lesser extent in summer by what happens on top. In terms of total volume of melt & freeze, most of it happens on the top & bottom surfaces, not the edges.
So for a large chunk of ice. If it is say 4 meters thick at the height of winter, it might melt down to 2 metres thick at the summer peak. It's area hasn't changed much even though its volume has halved. So measures such as Extent or Area won't record much change over the seasons. But what if succesively each year it starts at a lower thickness? 3.5, 3, 2.5, 2.0? At 2.5 metres nominal thickness, at the height of the melt season this has dropped to 0.5. Thin but still there. And only moderate changes in area/extent still. However, if it starts the year at 2.0 and melts by 2.0 to 0.0, its entire area is lost that season. Suddenly the Area/Extent measurements are reporting huge declines because the thickness at peak-melt has dropped below zero - completely melted. Even though the year before may have still had 0.5 residual thickness and only a 'normal' decline in Area/Extent.
Volume/Thickness is overwhelmingly the metric that lets us know when we are close to the point where the Area/Extent figures plummet. If the volume figures continue the trend they have shown now for many years, we are only 1-3 years away from the point where the Area/Extent numbers crash because too much of the ice has reached a simple state at the end of the melt season - negative thickness.
When I look at the data from PIOMas, even ignoring expnential vs geometric vs Gompertz fits, it is impossible to imagine those trends continuing for more that 1-3 years without large areas of the Arctic registering negative thickness in September.
And the PIOMas data shows no sign of reversing yet.
There are a range of positive feedback processes that can and perhaps already have driven accelerating volume decline. Many of these may well fly 'under the radar' of the existing Ice Models because they reflect secondary effects that escalate radically only under terminal phase conditions.
Ultimately, when I look at the PIOMas data, the model predictions just look unphysical. Because I can't see what would cause a cessation or reversal of the PIOMas decline. And that is what is needed for the models to pan out.
I'm not trying to diss the ice modellers, but I suspect they haven't been able to put the resources into terminal phase modelling needed because they are still working on the broader general models. And the Mother Nature has simply outrun them.
"Let me state first, I don’t know what the ice models actually model." Err, perhaps this might be a good first step? At least in a general way, maybe not down to the lowest level details?
conolley, so you define what is right and what is wrong?????
[In spelling and address, yes. You're being impolite because you can't be bothered to spell my name correctly. That level of slovenliness on your part is offensive. You're also being impolite in using my raw surname - see http://en.wikipedia.org/wiki/User:William_M._Connolley/For_me/The_namin… -W]
do you yourself consider a teacher or because you are the blogmaster here then by definition you dispose of the truth or what?
who do you define incivility? does it also to you?
[I think you need to read the comment policy. In this case, as I understand it, you're objecting because I copied your spam to the spam thread. But spam belongs in the spam thread, so I'm not really sure what you're complaining about. If you have something new to say, then say it. If you haven't, don't -W]
william connolley, you are overly sensitive. i do not accept your self-authorization as referee regarding scientific topics, for instance which factors effect a sea level rise. when i explain to you that complete arctic sea ice melting does not at all result in a measurable sea level rise because the ice is already swimming in the water, this is plain truth and everybody knows it.
[No, its wrong. I've provided a link, in a previous comment; here it is again: http://moregrumbinescience.blogspot.co.uk/2009/04/ice-and-sea-level.html Its no good you simply insisting that you're right and "everybody knows it". You need to read, patiently, what I've pointed you at; understand it; and then, if you can, point out the flaw in its reasonning. Alternatively, you can try to create a chain of reasonning to support your own assertion, in which case I'll tell you what is wrong with it. But merely stating that its true because you say so is pointless -W]
your remark about arctic albedo changes has to be scientifically investigated (real not only models). please cite references of peer-reviewed articles which demonstrate what you claim, i.e. that arctic albedo changes affect the mean sea level.
[I'm surprised you're so ignorant about this. The ice-albedo feedback is part of the reason that climate sensitivity to CO2 change is about 3 oC for 2xCO2 -W]
the problem with you is that you are not an expert regarding weather and climate. you are a computer programmer and not a meterorologist, therefore you have no profound understanding of the physical phenomena in the atmosphere and on the surface of the earth. i would recommend to you that you abstain from the temptation to position yourself as an weather and climate expert which you are not, as already said. stick to truth and honesty, please
[I'm a software engineer, not a computer programmer. But I *was* a climate modeller. But if you're attempting to restrict debate only to those people who are experts: why are you talking? You're clearly not one yourself, your own rules should force you to silence -W]
william connolley, you are guest on an american blog web site: hence behave accordingly. americans have no sense for and even hate your sticking to your snobbyish british formalism.
[Nah, you know the yanks, they just love our stuffy English class structure, it gives them a sense of depth of history they so badly lack. In fact even plebs like you like it really, or else why would you be here? -W]
in the land of the free and the home of the brave you are perceived as a weird foreigner,
[I should damn well hope so, there is nothing worse than being called normal -W]
overly focused on superficials things. i have never seen somebody like you who has created a special article on how to address his royal highness correctly. that's truly ridiculous.
[If you're a fan of the truely ridiculous, I recommend reading the rest of your comment. I was going to burrow it, but its too funny to deprive others -W]
some instructions to you, which you should learn thoroughly:
1: there is no difference between a computer programmer and a software engineer. a software engineer has to be able to write computer programs, and a computer programmer has to be able to design computer programs. so don't be too proud to name yourself a "software engineer". i own a series of flourishing companies, one of them working in the it area with many computer programmers (a few of them called senior technical consultants, others senior software engineers, etc.) so you should be silent when talking to me about computers.
2: what you don't know: i am a scientist you are not. but i understand that you want to be one and are suffering that you have not reached your goal.
3: you are extremely poorly informed about co2 climate sensitivity: direct co2 sensitivity is somewhere in the range between 0.7 and 1.2 degrees celsius, and feedbacks are scientifically not convincingly demonstrated: e.g. the ipcc third assessment report concedes a low scientific understanding of two major feedbacks: clouds, aerosols. hence your assertion that a doubling of carbon dioxide will result in a 3 degree mean global temperature increase is far from proven, or in other words highly improbable: you must learn what your own godfathers have tried to teach you: READ THE IPPC REPORTS, PLEASE!!!
4: your remark "You need to read, patiently, what I've pointed you att; understand it; and then, if you can, point out the flaw in its reasonning. Alternatively, you can try to create a chain of reasonning to support your own assertion. But merely stating that its true because you say so is pointless" is pure arrogance. you have to take note that YOU ARE THE LAYPERSON HERE AND NOT ME, even if you don't like this fact.
5: unfortunately, since you are no scientist, it is difficult to discuss with you in the manner which is usual among scientists. you are just a lobbyist of a climate side which appears to you emotionally "right" and you behave and argue only according to your preferred "truth": you are not able and willing to look at the weaknesses of your climate world, the methodological weaknesses of climate science in gathering objective data (temperature, sea level altimetry, other remote sensing) for instance: you think that everything from your alarmistic climate side is right because you are so profoundly convinced like a religious belief. you act partisan and not scientifically objectively. therefore you don't understand why modern climatology has to be blamed "postmodern" science because of compromising established principles of normal science (scientific methodologies, etc.): but unfortunately you are even not in the position to understand what i am telling you since you have no idea what science really is. and you are not willing to learn, not a little bit, on the contrary you are so stubbornly fixed on what you think is true: AND THIS IS NON-SCIENTIFIC BEHAVIOR BUT PURE RELIGIOUS BELIEF. like it ot not.
bill conolly, look how cold it is today in antarctica, and what a big difference there is to your unreflected above saying about antarctica (antarctica is getting warmer and things like that which correspond to your prejudices of a catastrophically heating co2 world)
the current temperature at the south pole:
2012.09.10 1750 UTC
Wind from the ESE (120 degrees) at 7 MPH (6 KT)
Visibility 2 mile(s)
Sky conditions mostly clear
Weather Ice crystals
Temperature -94 F (-70 C)
Windchill -126 F (-88 C)
Pressure (altimeter) 28.35 in. Hg (960 hPa)
indeed extremely warm, but i would not recommend to uncle gore and uncle hansen to visit the south pole right now for a warmist lobbying show to demonstrate catastrophic global warming in front of world tv cameras. bad luck for you that there is nil melting today of south pole ice shield ice and therefore no contribution to sea level rise.
you, as an it guy should be careful to try to teach other peope in a field, namely meteorology, where your track record is zero and formation completely missing.
"bill conolly, look how cold it is today in antarctica, and what a big difference there is to your unreflected above saying about antarctica..."
Imagine that, during the Antarctic winter too! I bet the warmist models didn't see that coming! A cold Antarctic winter! Take that, greenhouse effect! Hello, Ice Age!
"More popcorn in aisle three, please!"
[Tut, you're easily amused. Anyway, surely the discussion is over? Kai has completely destroyed any idea of global warming - if it was cold in on part of Antarctica on one day, GW is logically impossible, no? -W]
billie, your are absurdly wrong when you think that americans like british class thinking and behavior. quite on the contrary, practically all americans laugh about british snobiety and find british englich pronounciation (like the royal family) hardly bearable and profoundly snobbiysh. and your statement that british class structures are missing in the us and therefore admired, because americans suffer from their short history without a king and nobles is the summit of ignorance and arrogance.
you have a profound misunderstanding of american culture and the way of life, of the land of the free and the home of the brave
but always look at the bright side of life, tadaa, tadaa tadaa tadaa tadaa, tadaaaaaaa
without carbon dioxide, tadaa, tadaa tadaa tadaa tadaa, tadaaaaaaa
William, as I am also following the Lewandowsky issue, Kai is indeed very amusing!