It will be interesting to see which “skeptic” site or blog will be the first to show your naïve sea ice thickness time series WITHOUT the accompanying caveat, and maybe even use it to accuse POIMAS of cheating in preparing their volume trends.
Sea ice thickness varies by many many factors, from ocean salinity, temperatures, sea temperature convection, mirrored by atmospheric similar variations from above, is a complex issue made simple by the equation result in the form as simple as frozen water, we try to reverse engineer this result without having all the equation variables at every spot over an extremely wide area.
Given that there this much work about sea ice which will take a while to resolve, there is another method of sensing its decline, another equation like the one giving ice thickness which has nothing to do with looking at the sea. Another way would be to look at boundary layers, which are no mere strictly local product, but rather the result of the ice to air dynamic. This I literally do. It agrees that there are natural variations, but the whole underlying trend is that low troposphere boundary layers are rapidly changing looking like Southward ones. I again emphasize that a comprehensive compilation of Upper air low thermal layer trends will show what I mean… But there is another way, more powerful and sensitive than with radio sondes.. More on this in a few weeks. Mean time why not study boundary layers while having fun with a good mystery like the Titanic? http://eh2r.blogspot.ca/ We the people of “unsinkable earth” of infinite resources need to study.
I wonder, given the arguments presented here that six month projections are weather and three year projections are climate, if the sigmoid is properly applied to September ice volume? The amplitude of the April to September variation seems fairly steady so far suggesting that weather influences are not changing all that much. The slopes shown in fig. 1 are similar and if anything are divergent rather than convergent as an emergent sigmoid behavior in September would require.
Might in not be better to introduce a effective negative ice volume of warmer water that delays in refreezing to produce the April maximum? Then the problem of trying to meet zero volume with an artificial fitting function would not provide and artificial constraint. In that case, linear extrapolation could be performed. Extrapolating based on date from 1980 to the present yields and estimate around the 2040 for zero September ice volume while using an apparent steeper trend since 2000 yields an estimate around 2015 for the lower curve in fig. 1 or around 2020 using the upper curve as a guide.
The argument about piling up seems a little weak to me. You need a source to pile from, and that source is diminishing according to the upper curve in fig. 1. Sigmoids certainly do occurs in nature. But, I’d expect it to turn up in the April data eventually rather than the September data simply because the September data is mostly dependent on the April data as an initial condition and we certainly do not expect that drop to level off anytime soon. Shallow coastal waters that cool quickly may provide lingering April ice in the Arctic in 120 years or so, justifying a sigmoid treatment of the source function at that time, but perhaps it is not appropriately applied to September data now.
“In the space of one hundred and seventy-six years the Lower Mississippi has shortened itself two hundred and forty-two miles. That is an average of a trifle over one mile and a third per year. Therefore, any calm person, who is not blind or idiotic, can see that in the Old Oolitic Silurian Period, just a million years ago next November, the Lower Mississippi River was upwards of one million three hundred thousand miles long, and stuck out over the Gulf of Mexico like a fishing-rod. And by the same token any person can see that seven hundred and forty-two years from now the Lower Mississippi will be only a mile and three-quarters long, and Cairo and New Orleans will have joined their streets together, and be plodding comfortably along under a single mayor and a mutual board of aldermen. There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.”
- Life on the Mississippi
[Response: Wonderful. Thanks for the quote. - axel]
The piling up comes mostly from the Greenland glaciers, with minor contributions from other land forms. These will remain long after the Arctic becomes ice-free. The winds and currents will have an even greater impact as the ice retreats from open areas near the North Atlantic towards the Canadian islands.
Figure 4 may be the most telling, with 2040 being an extreme low end for estimates of an ice-free Arctic.
Also good to remember is that there is a high probability that the effects of Arctic sea ice decline are felt before the Arctic becomes effectively ice-free (below 1 million km2 sea ice area at the end of a melting season). And it’s those effects that are interesting to us, not some satellite picture showing a small blot of ice north of Greenland and Ellesmere Island (however spectacular a sight it will be).
Excellent article. I was just speaking with someone yesterday about the difference between possibility and probability regarding arctic ice. At least now I can speak with slightly more understanding of the difficulties in predicting when.
The take away here is that ‘if it be not in the morrow then it be yet to come’.
It should be noted that there is such a mismatch between the ice volume shown in the lower curve in fig. 1 and that shown in fig. 4 that is seems unlikely that they represent the same time period. According to the PIOMAS website, the average ice volume in September between 1979 and 2010 was 12,300 km^3 in apparent agreement with fig. 1. In the models shown in fig. 4 however, the corresponding value appears to be about 18,000 km^3. This suggests that the extrapolations in fig. 4 are not for an ice-free September, but perhaps for an ice-free July. If we are not comparing apples with apples, worries about fitting functions are a little premature. It is virtually certain that the first ice-free July will occur some years later than the first ice-free September. Earlier projections for September are not inconsistent with later predictions for July and there seems to be little evidence for the perils indicated in the title.
And of course, the implication would be that most of the sea-ice along the northern coast of Greenland originates as glacial ice, becomes part of an ice shelf, then calves off to become sea ice. To engage in a little hand-waving of my own, that seems highly implausible to me–the areas of ice shelf are much smaller than the area of sea ice.
In general, my impression is that your suggestion is an instance of “the tail attempting to wag the dog.” Of course, I’m open to actual evidence suggesting otherwise–though perhaps a tad skeptical that it will be forthcoming. ;-)
Ah, now I can see fig. 3. An arbitrary time-shift has been introduced to deal with the volume mismatch I noted above. Yet, even so, the data diverge rather dramatically and significantly from the models. This most likely suggests a deficiency in the models. It would be good to know how much volume they predict in April. In any case, they do not seem to have skill yet and do not seem useful for extrapolation for this purpose. If the authors had adopted a volume shift rather than a time-shift, the models would predict zero ice volume around 2060. But, the models still would not get the observed slope right. So, again, what perils?
[Response: Chris, I agree that the mismatch in total volume suggests that the CCSM4 overestimates the total ice volume. I am much less sure that the divergence between the PIOMAS ice volume and the CCSM4 ensemble mean (after shift) has anything to say about the whether CCSM4 is deficient or not. For the first 20 years of the time series PIOMAS and the CCSM4 ensemble mean track very well. For the last 10 years CCSM4 PIOMAS shows a steeper decline. Is this because of a deficiency in CCSM4 or maybe because natural variability gave us a particularly steep decline in sea ice over the last 10 years? A comparison of reality with the ensemble mean is not the measure by which to judge this. A comparison of observed sea ice decline with the model ensemble spread can tell us only how likely an observed trend is relative to that ensemble. See the Winton 2011 reference for an attempt to assess whether or not the observed sea ice time series fits with expected declines from the coupled models.
The real difficulty is how we assess whether or not a model represents the natural variability correctly at the relevant time scales. With only 30+ year time series of sea ice extent or volume, this is something difficult to do so we have to strive to construct longer time series that allow an assessment of natural variability at those times scales.
It takes a modeler to say something like that, but it was explained it to me may years ago like this: "Reality is only one realization of an ensemble". It has worked for me. - axel]
This is–I belatedly add–an excellent article–informative, provocative and judicious.
I must admit to a gnawing feeling of unease, though. (Of course, “feelings,” whether of unease or anything else, have no standing in the court of scientific validity. But, as Hank likes to say of himself, “I’m just a guy on a blog.”) From the post, the decline in volume is real, and has been occurring over much longer than the 3-year ‘period of memory’ for sea-ice.
But record of volume is not just an abstract dataset, of course. Given the large energies associated with phase change, it’s also a proxy for the whole Arctic heat budget. Viewed in that way, the data says that the Arctic is warming even more in terms of heat content than we would think, based upon purely thermometric considerations.*
That in turn begs the question, what is driving this imbalance? I presume that we don’t know that in detail yet, since if we did we would have a model that would be highly consistent with the observations–a robust one, perhaps I should say. But it does make one wonder, why the apparent consistency despite the variability on short timescales? Could the “heat imbalance” reverse sign for more than a year or two? (Clearly it must have (virtually, of course) in Tietsche et al. (2011.))
Or is this imbalance more highly determined (perhaps I should say “tightly constrained?”)–in which case extrapolation won’t prove such a bad guide in the present case after all, (appropriate) cautions above notwithstanding.
*I should acknowledge that this isn’t my idea; I first encountered it as presented by Gareth Renowden, of “Hot Topic.” Even blog science can cite…
Chris Dudley: “It is virtually certain that the first ice-free July will occur some years later than the first ice-free September.”
Why do you say that? Anyone with any experience should recognize that the first ice-free conditions will arise due to a confluence of factors – just as the first ocean waves covering drowning Pacific islands will be due to a unique confluence of factors – tides + winds + global warming. Later on, the condition will become ‘normal’, as warming progresses throughout the end of this century (and we can be sure of that, just not the degree of warming).
So, it all depends on weather and ocean current conditions in the Arctic through the summer, and as all know, those are not very predictable from week to week, and Arctic subsurface ocean temps are poorly monitored at best. Hence, there’s no way of telling in advance if the first completely ice-free week will be in September or July – and it really doesn’t matter which. It will arrive, you can be sure of that.
I see another conceptual difficulty here. If one invokes low frequency natural variability to argue against a near term projection, one has to get the low frequency variation to operate at high frequency in order to act in time to counter the short term projection. But, since it had to be low frequency to escape detection in the data, it can’t really do that. It would be better to argue that high frequency variability is not well estimated than to invoke low frequency variability in this situation.
Kevin, Dan H. is suffering from an orificial conflation issue pertaining to his locution on climate issues that may be congenital, but most likely includes nurture influences. From which orifice one speaks from is relational to ones talent in manifesting the Dunning/Kruger effect. In this, my opinion is that Dan H. is quite an expert, though likely without cognition of his ability in this area. Orifice loquation origination issues should be a new field of social psychology study though, as quantification in this area may help us choose politicians and teachers better in the future.
Dan H’s perception of where the ice is piling up from seems to be analogous to other piles that do pile up when one speaks from a particular orifice, analogically speaking of course.
The kinder interpretation is he is ‘speaking out of his hat’.
“Ice free” is important symbolically, navigationally and biologically but from the point of view of energy doesn’t a residual volume of “fixed” ice which doesn’t melt come to much the same thing? If summer energy input is no longer going towards melting sea ice it’ll go elsewhere. Where? Melting land ice sheets or warming the water?
Given the spectacular failure before ~2007 of the entire (relevant) scientific community to predict the very rapid decline in Arctic sea ice volume, there is indeed cause for humility in the expressing certainty in such predictions.
Even before I read the allusion to it above, the whole thing strikes me as if careful observers on the deck of the Titanic, having calculated carefully how soon the ship would hit the iceberg and subsequently sink, are suddenly surprised by the sudden jolt shuddering the whole ship. So now they are busily recalculating the range of possible moments at which the ship will actually sink, a calculation they want to get just right before presuming to prescribe any particular course of action to the ship’s policy makers.
I would humbly suggest that, while continued accurate measurements are always wonderful to have, the screamingly obvious main priority is loudly call for all to rapidly abandon ship–leave deadly fossil fuels behind and quickly climb into the lifeboats of efficiency, vastly reduced consumption, renewables, and population reduction.
Excellent article. Well reasoned and balanced. Quite a contrast to notable skeptics such as Joe Bastardi, who continues to suggest that the current downward trend in Arctic sea ice is simple cyclical thing and that there is no ice-free Arctic anywhere in our future whether it be 40 years or 240 years. I suggested to Joe that he really ought to stick with his weather forecasting and leave climate modeling and sea ice forecasts to others more suitably qualified.
On my blog I’ve been very critical of the extrapolation based claims of a rapid transition to a seasonally sea-ice free state. It’s good to read key issues being raised here in the main post. I’m still of the opinion that the extrapolation of data is useless.
However recently I’ve found myself wavering on the issue of how fast we’ll see a transition to a virtually sea ice free state (less than 1M km^2 off the Canadian Arctic Archipelago and the north of Greenland) and it’s because of the PIOMAS volume results. Rather than link to my blog posts, which were written as I worked on this issue so aren’t as succinct as they could be, I’ll summarise here.
This shows two step drops, one in 2007 being the result of the crash of that year, the other in 2010. These step drops are not exceptional in the full context of 1979 to 2011, however there are other facets that make 2010 worthy of note.
The 2010 and 2011 drops are due to a substantial volume loss in the Spring. The following graphic is of daily volume anomaly using the baseline of 1980 to 1999.
Prior to the 2000s the volume anomalies show drops at various times throughout the year. The coincident Spring volume losses of 2010 and 2011 stand out in the series from 1979. Using the naive calculation of thickness from the Cryosphere Today area index it can be seen that, if real, these volume losses imply a substantial loss of thickness.
In the above figure you can ignore ExtentThickness as I’ve moved over to calculating AreaThickness, using area alone. Kevin O’Neill (a commenter at my blog) and I have been referring to the relatively flat area through the Summer as the ‘roof’. Its implication being that during the Summer volume loss has been largely accounted for by loss of area, hence thickness changes little. However in 2010 and 2011 this changed, with loss of thickness being ‘needed’ to account for the loss of volume. As the above graph shows this is unusual behaviour in the context of the full PIOMAS series.
Using NCEP/NCAR reanalysis the only weather that stands out as being anomalous is a high pressure system over the Arctic in 2010 presumably related in some way to high temperatures. However as the area was ice covered at that time increased insolation wouldn’t have caused high temperatures, although inflow of air or large leads/polnyas could. Spring 2011 was rather unremarkable from what I can see.
I have heard that Dr. Maslanek projected that the Arctic would be ice free between 2013 and 2019. You did not refer to this projection in your article. Was this ever published? What do you think of this model?
How does PIOMAS account for changes in the amount of heat coming into the Arctic from ocean currents? Recent articles suggest that the heat content of the currents in the Fram strait have increased in recent years. Do these currents affect the ice significantly or is the heat content of the currents too small to affect the ice. Where does this heat go? Can you suggest a review article about heat contents of currents into the Arctic?
Excellent article. It is really good to see what real scientists think about the sea ice. Write a summary post for the sea ice blog.
I’ve long suspected that anthropogenic black carbon (and possibly other dark aerosols) are responsible for some of the downward trend. Do the necessary albedo adjustments to PIOMAS show any time trend? If so, is it possible to estimate how much annual melting could be averted if black carbon emissions were curtailed? Are there other methods for estimating the magnitude of the effect?
If we are to lend credence to Recovery mechanisms of Arctic summer sea ice, by Tietsche et al, shouldn’t the arctic have ‘recovered’ after 2007? While we saw a brief upward blip in September extent in 2008 -2009, volume losses continued. There was no recovery.
As Chris Reynolds points out in comment #24, there has been a significant change in the ‘average thickness’ graph (where average thickness is simply calculated by PIOMAS volume / CT area). It’s not just that the ice is thinner, but that the shape of the graph has changed. Prior to 2009 volume and area decreased at the same rate through most of the melt season, since then volume is decreasing at a faster rate than area during the summer months. The change is visually striking – where once there was a pulse waveform with discernible width there is now a sinusoidal waveform.
What Chris didn’t say (because neither of us has any idea of how to interpret it) is that if we take PIOMAS volume and divide it by EXTENT instead of area we get a different ‘thickness’ waveform. ‘Area thickness’ and’extent thickness’ each have their own characteristic waveshapes. These two totally different waveshapes have each morphed into the *same* waveshape today – essentially a sinusoid.
We may not be smart enough to know what it means – but we can definitely see that something has changed that no one is taking notice of or talking about.
[Response: That’s a misinterpretation of the word “recovery”. The paper simply demonstrates that if you remove the sea ice in July it will recover to the point where the current climate wants to have it. The earlier change in the 2010, 2011 thickness anomalies that Chris R. points out are very interesting. I would be careful though to attribute those to any “transition” of the system to some new state. We may have simply had a couple of warm springs as Chris R. shows.- axel]
“In summary, we think that expressing concern about the future of the Arctic by highlighting only the earliest estimates of an ice-free Arctic is misdirected.”
I really don’t agree with this? Surely the precautionary principle argues that we ought to take the pessimistic estimates as a better planning basis than the model average? Given the probability that ice loss leads to existential threats by disrupting the weather patterns we rely on for agriculture – I don’t feel odds of 50/50 on being “right” are good enough in this case.
As I understand AMEGs statement they aren’t really making a forecast per se, more drawing attention to the fact that 1-2 years of above average melting could lead to loss of most of the ice and subsequent risk of both severe disruption to weather patterns and risk of a significant increase in methane emissions.
I remember only a few years ago people were talking about end of the century or later for ice loss – and as events unfold we seem to be rapidly reeling this estimate in closer – prudence would lead me to assume it best to take a pessimistic view in case we continue to shorten our estimates.
To be more clear – I appreciate the abstract scientific debate about this – but also believe we need to be planning effectively in the here and now, which means considering the worse end of the range to avoid being caught out!
[Response: Douglas, I have no issue with anyone providing a more “pessimistic” estimate. If anyone has one, they should explain their rationale, provide some assessment of the uncertainty, and subject their estimate to some review. That’s the scientific process. I don’t think we should bypass this process to achieve a particular political outcome. If someone can make a solid case for why the issues we mention are unimportant and that a skillful long-term estimate based on extrapolation of PIOMAS can be made, they should definitely go for it and let us know. We love to see our work put to good use. - axel]
I’m confused (again). Figure 1 shows ~4,000km3 in 2011 with a -3,100km3/decade trend. That leaves a linear trend to zero at ~2024. Figure 3 shows a PIOMAS trend hitting zero in 2015 (exponential) and 2023 (sigmoid)
Then, the last statement seems to toss PIOMAS in the dustbin by predicting 2040-2100. Are you guys saying PIOMAS is crap?
[Response: No. they are saying that extrapolation of complex non-linear systems using straight lines (or sigmoids etc.) are not reliable methods of prediction. - gavin]
Apologies if this has already been linked and I missed it. But Neven on his Arctic ice blog recently had post discussing the limits of curve fitting for making projections about Arctic ice volume that people might find interesting:
“If we are to lend credence to Recovery mechanisms of Arctic summer sea ice, by Tietsche et al, shouldn’t the arctic have ‘recovered’ after 2007?”
Not necessarily, no. As I recall the paper, it didn’t show that the ice would recover in some quasi-automatic fashion, it showed that it could recover from the ice-free state–that a seasonally ice-free Arctic is not a ‘tipping-point’ per se. (I believe earlier work reached the opposite conclusion; perhaps a moderator or knowledgeable commenter can elaborate?)
What the ice actually does in a particular year depends upon the ‘forcings’ (to misapply a term, perhaps) actually occurring–net ocean heat fluxes, net radiative fluxes, winds and currents (especially, but not exclusively, as they determine ice export to the North Atlantic.) As I recall Tietsche et al., the assumed post-ice-free ‘forcings’ were relatively conducive to recovery. (Again, I’d love to hear a better summation from those who know this topic better than me.)
I think you may have misunderstood the intent in my previous post. The sea ice does not originate in Greenland of any part of Canada. The references was to the landforms present in the Arctic which serve to shelter the ice from warmer ocean currents from the Atlantic. “piling up” occurs when the winds and currents push the ice landward, into cooler air and waters. Without the heat transport characteristics of the open Arctic, the sea ice cannot melt as readily as elseware. The NSIDC website has a nice visual on this:
Excellent piece, thanks!
However, the final sentence, is somewhat unsatisfying. So sure, I get the argument that it’s not a particularly useful question to ask, but that won’t stop lots of people asking it, and there is some value in trying to answer it as honestly as possible.
So it seems you have a very conservative estimate from the CMIP ensembles, which are known to suffer from various weaknesses wrt sea ice, and which certainly don’t capture the trends over the last decade or so.
Then there’s models like PIOMAS, which, as you’ve argued, give us the best assessment over what has happened over the last couple of decades, but for which there are many problems with extrapolation.
You’ve argued that some extrapolations are more better than others, particularly those that take the physical properties of the ice into account; hence we should prefer a sigmoidal extrapolation rather than linear or polynomial.
But it really doesn’t then make sense, having weighed up all the strengths and weakness of each approach, to simply come to the conclusion that we should stick with the old CMIP projection of “between 2040 and 2100″. There is clearly enough evidence to at least add a caveat to say it *might* be much earlier. I think a more honest conclusion is projections based on PIOMAS are at odds with the CMIP projections, and at this point we don’t have enough evidence to prefer either.
[Response:Steve. Thank you. I think “might” has little useful scientific meaning. You’d have to assign some kind of probability threshold. Let’s say we define “might” as a 5% probability that the Arctic ocean is going to be ice free before 2040? How do you determine this probability? I can’t see a way other than looking at models. Coming up with this probability is a scientific problem that needs to be carefully pursued, will involve coupled models, and will take time. Dismissing the models as “biased” and extrapolating observations in our view is not a good alternative to this process (see also 13). - axel]
But surely they have made at least one error here. The butterfly being wafted around by errant breezes and stirring up storms in Beijing with its wing flutters can still consider the usefulness of a liner extrapolation of the effect of the semitrailer 2 yards away and approaching at 80 mph. Invoking 30 year timescale variation to besmirch a 3 year projection is a little off base.
It also seems to me that insisting that the behavior of a demonstrably non-skillful model, CCSM4 AR4 runs, should be used as a guide is a little backwards. Why can’t the model get the volume right in hindcast rather than being off by 30% should be the first question. PIOMAS gets ground truthed by a large number of mechanisms. The free running models should be looking for unwarranted assumptions that may explain why they are off rather than insisting that the world should behave as they predict rather than as it does. They somewhat admit this but then proceed in that manner anyway.
Based on their choice of time-shift rather than volume shift to “correct” the models, I’d suspect that an assumption of lingering ice is built into the models. Perhaps it is assumed that piled ice always piles to the same thickness even if it comes from a thinner source, creating volume unphysically, or something of that sort. Surely we might be just as justified in subtracting 10000 km^3 from the model ensemble shown in fig 4. as a volume shift “correction” to match the 2011 volume minimum and get a number of realizations that are ice-free in short order, two even that would have been ice-free a couple years ago. Then, at least, the spread in the model runs could be put to some use.
It is the rare non-linear system that cannot be linearized usefully for at least the short term. That is why we use Taylor expansion so often.
[Response: Chris, See above in response to your 13. See also http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/validation/Fig13b.png for a comparison with the CCSM3 model for which no time shift was necessary. PIOMAS ice volume is reasonably within the ensemble spread of the CCSM3. The CCSM4 has a lot of natural variability which emphasizes our point: unless you can somehow quantify and separate the contributions of natural variability and forced variability to your observed time series, extrapolation will be problematic. This is of course less so for shorter projections than for longer ones. Why the CCSM4 is different than the CCSM3, whether or not models represent natural variability correctly, and whether the multi-model ensemble is a proper point of reference to measure the state of the art is a different debate. I think this debate needs to happen, it is happening. New predictions and improved models will come from it. I don’t think extrapolations are an adequate substitute for it.
If you think you can make a skillful long-term projection by extrapolation, I encourage you to show that you can. You’d probably have to go to the models to do so. If you come up with something, that would be a very interesting paper and I would be sure to cite it frequently. - axel]
#38–Yes, Dan, that’s a very different message than what you appeared to be saying in #7. Thank you for clarifying your point; I think that inclusion of the “glaciers” muddied the waters for me. (Surely the presence or absence of glacial ice doesn’t greatly affect the “piling up” of sea ice against the shore–or terminal ice shelf–by persistent wind and current out of the North?)
Anyway, what you apparently were trying to convey seems pretty consistent (as clarified) with both the post and with the NSIDC Arctic Analysis page you link to.
BTW, I don’t get why you characterize 2040 as “an extreme low end for estimates of an ice-free Arctic,” based upon Figure 4 of the present post; the earliest zero intercept looks to me to be about 2025. (That’s the sigmoid fit in yellow, and *everything* that hits zero in that figure is a sigmoid fit, if I’m reading correctly.)
I could see how my earlier post could be misinterpreted. Sorry about that.
True, the earliest intercept appears to be around 2025, but the highest is near the end of the century (using the 1979-2011 data). Estimates using the longer dataset are further into the future, due to the removal of natural fluctuations.
The simple curve fitting will treat all the sea ice as equal. However, as described in the article, that is not the case. Southern expansion into the North Atlantic and Bering Sea will encounter more heat exchange with the open ocean currents than the ice northward of Canada. Also, in mathematical terms, the volumetric loss will be tied to the amount of remaining ice. In order for the volumetric declines to keep pace with past calculations, the decline in sea ice area must accelerate. As the sea ice retreats, the volumetric losses must decrease, as shown in Figure 3. Hence the extrapolated fit to 2015, sigmoid fit to 2025, or other curves seem to be the outliers. I think is the main point of the article.
It is worth noting that in using a time-shift in fig. 3, 2040 in model years is shifted to 2020, the region of interest for early ice free conditions. However, Varvus et al. note that “CCSM4 simulates a hiatus in the secular Arctic climate trends during a decade-long stretch in the 2040s” http://www.cesm.ucar.edu/publications/jclim10/docs/vavrus.ccsm4.arctic_climatechange.pdf Thus, a time-shift of this model data set may be somewhat biased when applied to this particular question. However, having introduced the shift, allowing the 2070 estimate for ice-free conditions from CCSM4 to stand unaltered seems a little inconsistent. It should also be shifted to 2050.
One more thought on Varvus et al. While they report ice-free conditions occurring in 2070, examination of their fig. 2 reveals that this is for the model ensemble average. In particular realizations, ice-free conditions come an average of 7 years earlier (using their threshold). This is typical behavior of a descending trend with variability and eliminating the variability using the average introduces a bias. Thus, in consideration of comment #43 above, CCSM4 really predicts ice-free conditions in the early 2040s after the time-shift introduced in fig. 3 above.
In all, it would seem that models and extrapolations predict ice-free conditions between 2013 and 2045. The latter happens to agree well with a linear extrapolation of the 1979 to present PIOMAS data (though to zero and with no accounting of fluctuations; comment #5 above). Thus, extrapolation and modelling appear to agree after a few corrections to the model interpretation and perils were merely imagined.
In the spirit of the SEARCH Sea Ice Outlook, let me suggest that the Gompertz and other simple extrapolations be considered a class of black-box, naive models against which the predictions of more elaborate and theoretically better justified physical models can be compared. They’re null hypotheses that have not yet been rejected; hopefully (because they tend to look pessimistic) they will be rejected in time.
A second note: although extrapolations are often drawn as clean lines or curves that give the impression of an absolute cutoff at date X, they can be viewed probabilistically as well, with uncertainty also naively extrapolated from recent real-world behavior. See Figure 2 in this post (cited as the “blogosphere” link above) for an example applied to sea ice exten: http://neven1.typepad.com/blog/2011/10/september-2011-sea-ice-extent-looking-ahead.html
“The simple curve fitting will treat all the sea ice as equal.”
I like that comment because it throws into sharp relief how much information is disused if one simply takes one number–extent, area or volume–as description of the ice. A simplified picture, to say the least!
“Southern expansion into the North Atlantic and Bering Sea will encounter more heat exchange with the open ocean currents than the ice northward of Canada.”
‘Fraid you’re losing me again with this sentence. What southern expansion? If you just mean that there is greater potential for ice loss in the North Atlantic and Bering sectors than in some others, well, sure.
“Also, in mathematical terms, the volumetric loss will be tied to the amount of remaining ice. In order for the volumetric declines to keep pace with past calculations, the decline in sea ice area must accelerate.”
Logically, no–mathematically speaking, area could remain constant, and then volumetric decline would be exactly proportional to thinning.
On the other hand, if volumetric loss is a good proxy for Northward net heat fluxes, as discussed in my comment above, then we might expect the volumetric losses to remain relatively constant, in which case they would represent ever-greater proportions of the remaining ice. (I take it this expresses the relation between volume loss and total ice you are thinking about.)
But which variable–proportion of total ice, or volume loss–is really the independent one? I’ve just presented a physical rationale for considering the volume loss to be independent; do you have one for the opposite view?
“As the sea ice retreats, the volumetric losses must decrease, as shown in Figure 3.”
I don’t see that in Fig. 3, FWIW. The modeled loss trends do seem to decrease, possibly due to negative feedbacks, but if there’s a ‘must’ in there, it’s not self-evident to me.
That is a good point that you can simulate fluctuations in an extrapolation. And, it happens to illustrate why a sigmoid function is inappropriate in this situation. Fluctuations about the sigmoid would produce ice in September long after the source ice from April can’t survive past June. Fluctuations about a linear extrapolation, however, would not rise above zero in that case. Zero should not exercise any false tyranny here.
While in theoretical and mathematical terms, ice area could remain constant; in physical and practical terms, it will not. To visualize this, consider an ice cube in a glass of water. All dimensions are likely to melt at similar rates, such that the surface area and thickness will decrease proportionally. The volume, however, will decrease as a product of the area and thickness, such that a 10% decrease in both surface area and thickness, will result in a 19% decrease in volume. When 30% of the surface area and thickness have melted, 50% of the original volume is gone. The surface to volume area is increasing. The surface area is constantly exposed to the heat exchange processes, and independent of the starting value. Volume is dependent on the starting value. If surface area and thickness continue at a constant rate, then the volumetric loss must decrease, resulting in the sigmoidal curves. If volumetric losses remain constant, then surface area and thickness losses must accelerate. Does this make sense?
Since we have not measured accelerated sea ice area losses, the logical conclusion is that volumetric losses must be decreasing.
As sea ice declines, we are left with some interesting competing effects. On the one hand, it will be colder,on average where we still have ice. Also, I’d expect the effects of black carbon to come into play less for more northern climes. On the other hand, the surface area to volume ratio will increase, as will the circumference to area ratio. The surface area to volume ratio means that an ever greater proportion of the ice is being irradiated, while the circumference to area ratio means more of the ice is being battered/warmed by the oceans areound it. This ought to be especially significant as ice withdraws and the oceans lower albedo leads to more absorption of sunlight earlier in the melt season.
Competing effects always lead to interesting dynamics–and it could be that we see a brief period of slowing followed by the ice disappearing rapidly like a water drop dancing on a hot skillet.
Guys I appreciate your work on this, but your scientific conservatism makes your conclusions seem unsatisfactory to me.
In terms of Shewart Control Chart Theory your system has “alarmed” three times in the last 33 years (Fig 1, using 2-sigma limits). (http://en.wikipedia.org/wiki/Control_chart) All three “alarms” have been in the downward direction. Although not definitive it would suggest the assumption of a linear trend is questionable. And if ensemble calculations are to be believed (Figs 3 & 4) the mean should be curving upwards rather than linear, which would make the most recent observations even more unusual. (What is you justificaton for not fitting an ensemble shaped trend?)
A minor issue is whether Fig 1 was constructed using the most recent data eg. 2011), which means it is not suitable for assessing whether that data is unusual. (i.e. To assess whether the record Sep 2011 minimum is unusual we would calculate the trend by excluding it.) Similarly the exponential and sigmoid fits are even more ad-hoc, being physically unrealistic and failing to fit the full time series. Finally the Fig 1 trends do show evidence of autocorrelation, so successive departures from trend are not as compelling as might first seem.
Getting back to the issue, yes it’s possible that this is still natural variability about a linear (or ensemble) mean, but it seems at least equally plausible that the modelling is simply WRONG. Such extreme short-term departures do not (to my eyes) appear in the models.
My conclusion is that you do not yet have sufficient understanding of the loss of Arctic Sea Ice and that it could be down below 1000 km^3 (i.e all gone with the exception of ice to the north of Greenland and a few other islands) as early as September 2014. True it may run it’s course and agree with ‘previous model-based predictions of somewhere between “2040 and 2100″’, but the evidence of MODEL FAILURE is becoming more compelling every year. Personally I’d be surprised if the Actic is NOT ice free by 2020, but that’s a guess! I would not be standing by the model predictions given the real world evidence.
If this continues, there is a point at which you must say, “The ice is disappearing faster than we can explain – all bets are off!”
Quite conceivable. The ice will also be retreating into colder regions, and encountering less ocean current. The possibility of volcanic activity would also alter the changes. All these competing effects will render most modeling virtually useless when it comes to actual numbers. As Neils Bohr once said, “Prediction is very difficult, especially about the future.”
“We believe that substantially skillful prediction can only be achieved with models, and therefore effort should be given to improving predictive modeling activities. The best role of observations in prediction is to improve, test, and initialize models.”
Coming from leaders in the field of climate science, your words frighten me down to the marrow.
I am a statistician who used to devise models for a bond rating agency. Models are useful tools but the financial crisis taught me (again) that, when the downside is steep and reality is very complex, we cannot afford to base our decisions on substantially skillful prediction. We must be very attentive to observations that warn us that extreme loss scenarios are more probable than our models predict.
How do you make predictions without models? Genuinely interested. All the cherry picked quote you have selected says is that prediction of changes for the phenomenon in question we need the best models. Hardly earth shattering stuff.
As for climate science in the round, models are just one line of enquiry so policy decisions are not based wholly on them. I suggest you read up some more.
As Neven points out, in #9, the effects of a collapse in sea ice extent will be felt long before the sea ice totally disappears.
Arctic warming is now driven largely by the albedo flip effect, as ice is replaced by water thus increasing the absorption of sunlight; see paper by Hudson . In the past three decades, the sea ice September extent has declined 40%. If there is a collapse in extent by a further 40%, that would double the albedo flip effect for that month. But the other months could have similar doubling, e.g. as a 20% decline increases to 40%. This would mean that overall the albedo forcing would double, and the rate of Arctic warming would suddenly double.
[Response: This actually doesn't make much sense. The energy for ice melting is coming from mainly long wave effects and some ocean heat transports, the albedo effect adds to that of course (but less than you might think because of cloud compensation), but a doubling of the albedo effect will not double the rate of melting. And since this is all standard stuff, it is all included in the GCMs, and yet they don't show the kind of behaviour you are postulating. - gavin]
Now, how soon could such a collapse occur? Here we can look at the PIOMAS volume, and consider how much further thinning can occur before the sea ice becomes so thin over most of the ocean that it will break up and melt away. The extent cannot hold out for many years if the thinning continues. The volume trend suggests that the thinning rate is increasing, indicating that a collapse in extent is likely to occur by 2015. The reliability of this assertion, and the evidence leading to this assertion, has been confirmed by leading sea ice expert, Professor Peter Wadhams, in his evidence to the UK Environment Audit Committee in their hearing on “Protecting the Arctic” .
If wind and weather conditions this year produce a decline in volume as between Sept 2009 and Sept 2010, then there could be a collapse in extent this year.
A collapse in sea ice extent would be a catastrophe for Arctic ecosystems and for creatures depending on the sea ice. But more worrying still, the sea ice is critical for holding back methane emissions from the shallow seas of the East Siberian Arctic Shelf (ESAS). When the sea ice is not present, storms can churn up the water, warming the seabed and thawing the frozen structures holding back the methane. Vast plumes, a kilometre across, have been seen in part of the ESAS area. There is a real danger of a destabilisation of methane-holding structures producing an escalation of methane emissions if the sea ice area were to further retreat. Unfortunately there is so much methane held under the ESAS seabed that only a small proportion (perhaps as little as 1%) released into the atmosphere could cause “methane feedback”: a vicious cycle of greenhouse warming  and further release.
[Response: This doesn't make much sense either. CH4 is a small fraction of the warming drivers, and as we saw with David's posts earlier, you need to have absolutely enormous methane releases to even make a dent. There is no evidence for that now, or in the recent past when Arctic sea ice was less extensive (specifically the Early Holocene or the Eemian). - gavin]
Thus the reluctant conclusion of Wadhams, and other members of the Arctic Methane Emergency Group, AMEG , is that drastic emergency measures including geoengineering must be taken as soon as possible in order to cool the Arctic rapidly and minimise the risk of sea ice collapse and methane feedback.
[Response: It is not a conclusion drawn by many others, and if you want to make a case for it, you need to do a much more quantified job. - gavin]
Note that, even if the situation turns out not be quite so dire, action should be taken on the precautionary principle; see Douglas’s comment #33. Why do advising bodies, such as IPCC, always seem to rely on optimistic forecasts, based on out-of-date models, in order to inform politicians of the situation?
[Response: Would you have them report on anything other than the current state of the science? Everything in IPCC has to be traceable to peer-reviewed science, and so that is what they will reflect. Note too that IPCC does not advocate for policy which is what you appear to want it to do. - gavin]
Sorry, skipped my Divination classes at Hogwarts, had to resort to science ;)
Comment by Axel Schweiger — 13 Apr 2012 @ 12:15 PM
Axel in #13 and #40,
Thanks for your responses. I guess I would say that the longest term extrapolation is about 30 years for the September sea ice behavior, about as long as the data set. It is risky to extrapolate that far. But, in some sense, we are treating the real world as a model realization when we do that, assuming that a system driven into motion may continue in motion if it continues to be driven. The numrical models also assume continued driving. And, the driving does seem to be more important than the non-linearities at least over those timescales. You may be able to get J. Richard Gott III at Princeton to write the paper you’d like to read. But, I don’t have a lot of confidence in the long extrapolation.
What I notice is that consistent corrections to the model, and attention to the behavior of the individual ensemble members brings model projections and the long extrapolation into agreement (#44) while short extrapolations probably should not be attacked based on possible low frequency variability owing to a scale mismatch. If the system has a tendency to hold trends, then a short extrapolation will have some predictive power. And, it seems to be the short extrapolations you are critisizing and perhaps on the wrong basis.
One other difference between the models and PIOMAS that I notice is that the largest ice volume anomaly excursions have been prior to minimum ice volume around July while Varvus et al. note a shift occuring to later minumum ice in the models. Perhaps there is a clue there? Is lower albedo first year ice playing a larger role near solstice than modelled perhaps?
Reports of recent “vast plumes of methane” are found in blogs and newspapers, but nothing Scholar turns up supports these stories. I’d like to see a first person account that can be fact-checked. Scholar finds e.g.
“From the characteristic vertical decrease of methane towards the sea surface, it is concluded that biota are extensively using this energy pool and reducing the methane concentration within the water column by about 98% between 300 m depth and the sea surface. Degassing to the atmosphere is minimal based on the shape of the methane concentration gradient.” http://www.springerlink.com/content/t06u8r17j2897340/
The above was published about 18 years ago; cited by about 20 papers.
This modeling study is consistent with that. I’d be inclined to look for trends in the microorganisms that consume methane.
“… Given the present bulk removal pattern, methane does not penetrate far from emission sites. …. a potential for material restrictions to broaden the perturbations, since methanotrophic consumers require nutrients and trace metals. When such factors are considered, methane buildup within the Arctic basin is enhanced. However, freshened polar surface waters act as a barrier to atmospheric transfer, diverting products into the deep return flow.”
Maybe we can hope for a bright green Arctic Ocean — a big increase in primary production, a big new CO2 sink, and a large new food source — if we can avoid polluting the area with industrial activity.
Dan H., #48–”If volumetric losses remain constant, then surface area and thickness losses must accelerate. Does this make sense?” Well, that’s what I said, too, so yes, it makes sense.
But let me note that while it may be the case that an ice-cube melting in a glass may tend to decrease similarly in all dimensions, it’s definitely not the case for the Arctic ice pack–thinning is clearly proceeding more rapidly than the decrease in area.
#31: Axel, inline comment, “That’s a misinterpretation of the word “recovery”.”
#37 Kevin McKinney
Perhaps I’ve misread Tietsche, but I don’t think so. It’s actually pretty hard to misinterpret ‘recover’ in this context. They specifically state that from 2000 on extent and volume “recover” to typical values by the 4th year. I see no evidence in their Figure 1 that any significant percentage of the ensemble exhibited anything like the real-world results we’ve witnessed post-2007. No note, for example, saying: In some ensemble members volume never recovered, but instead decreased at an accelerated rate. Perhaps that caveat was evident in the data – if so, it never made it into the paper. Instead we read:
3.1. Sea-Ice Extent and Temperature Anomalies
All our experiments start from sea-ice free conditions on 1st July. As expected, the Arctic Ocean remains ice-free for several months, and significant sea-ice cover does not develop before November. However, sea ice then grows very rapidly, since the growth rate for thin ice is much higher than for thick ice, which acts as a negative feedback on thickness during the growth season (Bitz and Roe, 2004; Notz, 2009). The ensemble mean September ice extent reaches values typical for the reference run in the fifth year after the perturbation for the 1980 time slice, in the fourth year for 2000, and already in the second year for 2020 and 2040 (Figure 1). September sea-ice volume takes longer to recover in the late 20th century when the sea ice is still thick, but it has the same time scale of recovery as sea-ice extent from 2000 on…
Axel. Thanks for the reference (and in an accessible form)! So if I have parsed the proper takaway conclusions. BC does have an effect, but BC inventories have been decreasing, so to the extent that BC contributes to melting, the effect is counter to the recent ice loss accelleration.
I find the BC declines a bit unexpected (for me at least), as I thought increased Chinese emissions were overwhelming other reductions.
The acceleration seems to date from around 2000 rather than 2007. The four years following 2007 had two minima above and two below the 2007 minimum, an even split though the downward trend seems to persist. It is not really as though everything started to happen after 2007. Tietsche et al. had similar behavior in their _reference_ run. The zero ice in July experiment they conducted is quite a different behavior that what we saw in 2007.
“I thought increased Chinese emissions were overwhelming other reductions.”
I don’t know this for a fact, but I suspect Chinese emissions of black carbon may *not* be increasing. It’s been well-publicized that they have been adding lots of coal-fired generation, but less-well known that the policy is to add modern, much more efficient plants and retire the dirtier, older ones. They are aware of, and concerned about, the high human and monetary costs of their filthy air. (The Economist, for example, recently reported the annual death toll due to air pollution to be something like 200,000.)
“Norbert’s legacy challenges those of us who engage in predictions to prove our skill and to understand and explain the limitations of our techniques so they are not used erroneously to misinform the public or to influence policy”
I’m sure that future generations will thank you for your caution about influencing policy in a way that might mitigate the disasters they will face.
Seriously, I think you should stick with doing the best science you can and leave the issue of influencing policy to others, because I don’t think you understand its basics. The influencing of policy in re global warming faces a huge amount of inertia, but principles of risk mitigation tell us that we should be aggressive about shifting policy to avert possible threats, the opposite of what results from that inertia. And in the face of scientific uncertainty we should be even more aggressive … the more uncertain, the more aggressive we should be.
I’ve now had time to read most of the comments and Axel’s responses.
“Reality is only one realization of an ensemble” – I realise this is in jest, but it does betray an unfortunate mindset.
Regardless of whether you use a linear or sigmoid extrapolation or a CCSM4 AR4 ensemble, you are using a model. George Box’s famous quote is, “All models are wrong; some models are useful”. It seems that CCSM4 models, whether time shifted or not, fail to account for the recent behaviour of Arctic sea ice. Not only are the CCSM4 models systematically high, but they fail in more important ways. If the recent declines are due to natural variability, the CCSM4 models appear unable to reproduce such extreme variability (correct me if I’m wrong). Time shifting CCSM4 models does not fix this problem as it does not affect that variability. As for this figure for CCSM3 (http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/validation/Fig13b.png), it omits 2010 & 2011, which means the PIOMASS is now well below the lower ensemble bound and declining much faster.
Alternatively if the recent collapse of sea ice is a genuine trend, the CCSM4 models are found even more wanting. Is it time to bin the CCSM3/4 models. I suspect yes.
There is nothing inherently superior in a complex non-linear model of a physical (or financial or biological or whatever) system that is, well wrong, either because it omits key processes or lacks fidelity to known processes. @350limit’s comments (#54) on the failure of econometric models capture this problem precisely.
It is very easy to be deceived by the inherent beauty and self-consistency of your models, plus all the time invested in them. But without evidence of their fidelity to reality how can they be given more credence than short-term extrapolations?
Thanks Tenney, I had seen that, but the closest it seems to get is saying “a substantial amount of CH4 released at the seaﬂoor in the shallow ESAS is delivered to the atmosphere (Shakhova et al 2010b, 2010c).” — is that documented in the 2010 papers?
Albedo Evolution of Seasonal Arctic sea ice
During the melt season the albedo of seasonal ice is less than multiyear
Seasonal ice absorbs and transmits more sunlight to ocean than multiyear
Albedo evolution of seasonal sea ice has 7 phases
Donald K. Perovich
Christopher Mark Polashenski
There is an ongoing shift in the Arctic sea ice cover from multiyear ice to seasonal ice. Here we examine the impact of this shift on sea ice albedo. Our analysis of observations from four years of field experiments indicates that seasonal ice undergoes an albedo evolution with seven phases; cold snow, melting snow, pond formation, pond drainage, pond evolution, open water, and freezeup. Once surface ice melt begins, seasonal ice albedos are consistently less than albedos for multiyear ice resulting in more solar heat absorbed in the ice and transmitted to the ocean. The shift from a multiyear to seasonal ice cover has significant implications for the heat and mass budget of the ice and for primary productivity in the upper ocean. There will be enhanced melting of the ice cover and an increase in the amount of sunlight available in the upper ocean.
Perhaps this mechanism contributes to acceleration in ice volume loss between 1979 and the present. If it has not been included in models, then the departure seen in fig. 3 might be partly explained.
“@350limit’s comments (#54) on the failure of econometric models capture this problem precisely.”
Indeed. I find the responses to those comments very problematic. Hogwart’s? 350limit did not say to resort to magic rather than science, only that the authors have been blinded by the latter … I would refine that to refer to certain elements of scientific culture that tend toward extreme conservatism in making pronouncements or urging action — this isn’t science, it’s sociology, and the comments about “influencing policy” and “a particular political outcome” are also not science, or scientific.
Just what “particular political outcome” are we talking about? The scientific question is when will the Arctic be free of ice (not whether, although it’s possible that it will not be — if human activities change in a way not reflected in any of the models). The political debate is, crudely, whether to take action to mitigate global warming or not. No matter when the Arctic will be free of ice, the fact that it will be is just one of many scientific indications that mitigating action is desirable. How might possible answers to the scientific question about the Arctic ice influence the two policy approaches, the undesirable one and the desirable one? Well, the later the end of Arctic ice comes, the more people can rationalize not acting. It is therefore reasonable and rational to focus on the possibility (an accurate probability estimate is not required) of the earliest plausible estimate … especially when the models have repeatedly underestimated ice loss. This is the rational conclusion that one can see when one is not blinded by certain science-culture attitudes and takes into account factors outside of the science of Arctic sea ice … factors such as political inertia, principles of risk mitigation, and the enormity of that risk.
Comment by Marcel Kincaid — 14 Apr 2012 @ 12:35 AM
Following from #57:
John Nissen: Note that, even if the situation turns out not be quite so dire, action should be taken on the precautionary principle; see Douglas’s comment #33. Why do advising bodies, such as IPCC, always seem to rely on optimistic forecasts, based on out-of-date models, in order to inform politicians of the situation?
[Response: Would you have them report on anything other than the current state of the science? Everything in IPCC has to be traceable to peer-reviewed science, and so that is what they will reflect. Note too that IPCC does not advocate for policy which is what you appear to want it to do. - gavin]
In my opinion the IPCC is a solid scientific body. I respect that. Although it seems a rather slow grinding process, it’s a remarkable achievement to achieve the degree of consensus that they do.
However, where I think they are either wildly optimistic or (more fairly) where they clearly state their own limitations – is where they tend to include caveats in their reports. Caveats that seem to be overlooked by policy makers. For example, their estimates are clearly stated and explained – but if there is then a list of factors that they are unable to assess or accurately predict which may make the situation much worse, these are clearly stated. Just because we don’t understand the system fully and have to ignore portions of it to achieve consensus science doesn’t automatically mean those portions aren’t important and significant.
My issue is that people in general, and especially policymakers tend to focus on the most optimistic outlook of what the IPCC present, which is to ignore factors unable to be included, many of which have quite negative impacts.
As events unfold and predictions are proved by events to have been too far into the future, it suggests we are ignoring these caveats too much – at our peril. As an abstract scientific discussion – great – we’re learning the truth. Unfortunately, if events run much faster than expected it brings on an existential crisis.
I personally wouldn’t get on an aeroplane if there was even a 5% chance it would crash en route. In fact, I would regard an aeroplane with a 1% chance of crashing on route as very questionable. By my logic I’d apply the precautionary principle rather strongly if there was even a small chance of major effects such as near future sea ice loss…
The response to my previous post was reasonable however – can one present an explicable hypothesis with some quantification of the risks one is running – definitely food for thought there.
In one of his earlier responses to a comment, author Axel Schweiger extols a discussion by Neven Acropolis on his Arctic Sea Ice Blog about use of various sea ice graphs. It concerned a graph used by the Arctic Methane Emergency Group, attributed to PIOMAS. In fact, it was just based on PIOMAS data, not from them.
On that page, Neven says his favorite such graph is this –
as it “shows all the different outcomes of different statistical approaches.”
I too think it is great, and heartily recommend to the Arctic Methane Emergency Group that henceforth they start using it in their literature.
The reason I mention the Arctic Methane Emergency Group (AMEG) in particular, is that Schweiger is hardly overly subtle that this whole blog piece is essentially written such as to be directed towards that group. The “Perils of Extrapolation” of the title finally comes to rest on a discussion of “extrapolation” which explicitly names AMEG at its outset, and concludes that, “Predictions of earlier ice-free dates (he means, before 2037) so far seem to be confined to conference presentations, media-coverage, the blogosphere, and testimony before to the UK parliament.” Of those four there are three links, one already used before from the sea ice blog – the other two are both from AMEG. At the beginning of his piece there was mention of “water cooler speculation,” and by this point in the article we know just who he was trying to demean.
But in fact, it is just in making this somewhat dismissive and pompous claim that Schweiger runs his argument completely aground. In 2007, when Al Gore spoke at his Nobel award ceremony, he mentioned the work of ice modeller Wieslaw Maslowski. Maslowski came under intense scrutiny afterwards, and in some interviews seemed at pains to discuss his modelling and its own prediction for a first ice-free September, which Gore had stated before the world (although the US press almost unanimously declined to include this in their articles about the speech) – could come by 2014. “Seven years,” Gore said in 2007, followed by a long silence. We’re still not quite there, so we don’t know. At times Maslowski seemed almost to retract or deny that this had been an accurate depiction of his own work. It has surely been a controversial kind of thing to say, let us all agree, and those who don’t like such predictions really don’t like them. Yet just last year, Maslowski and his group released an updated version of their sea ice model, which sees 2016 as the most likely year for such an arrival. http://www.sciencepoles.org/news/news_detail/maslowski_and_team_offer_new_estimate_summer_arctic_sea_ice_disappearance/
It has nothing to do with PIOMAS. But it is a model. It is hardly “water cooler speculation,” and I don’t know that I’d want to call it, “extrapolation.” In a way, even the use of that term becomes loaded in this article. I realize that Schweiger means this in a specific sense, but more generally, with all computer modeling, prediction of the future involves extrapolation. Period.
In one of his responses to a comment Schweiger says, ‘I think “might” has little useful scientific meaning.’ Unfortunately for him, in the real world, and specifically in policymaking, “might” must have meaning. One of the key problems in the last three decades of interaction between climate scientists and policymakers is that, under political pressure, those things that are highly uncertain – where the scientists’ ‘pdf curves’ look flat and flabby – tend to just get left out of the picture altogether. That makes for awful policy. It’s hard to take a sane or precautionary approach to problems if those rough and hazy “mights” of our future reality can’t be considered.
What Schweiger never quite deals with, in all his spiel about using his PIOMAS with hindcasts versus forecasts, etc, is that we simply don’t know what the sea ice volume is. He himself mentions that real data cannot tell us that because the data samples are far too slight. We know the area because we see it, but we can’t know the volume. But that means that we will never know what ice volume is for sure until it is zero. Of course that also means that AMEG doesn’t know when the ice will be gone, but they are really only saying that it might.
I think what is really bothersome here, almost offensive, is to see something like the agenda-driven tactics of Patrick Michaels and deniers right at the heart of establishment climate science. After all, it seems crystal clear what the underlying calculation was: since AMEG had engaged in “high profile extrapolation” using PIOMAS, and Real Climate found this not to be judicious, they decided to take them down and discredit them by getting those who have been working inside PIOMAS modelling to say that they had misused or misunderstood the model. And yet, while PIOMAS data was being used by AMEG, they actually didn’t need to use it for their fundamental argument at all – they could have used Maslowski’s model, for example. In this way, Schweiger never actually addresses the fundamental arguments involved in AMEG, since he’s only a modeller caught up in how to interpret his model. Undoubtedly, he’s highly competent and professional at that.
At the beginning Schweiger takes his hat off to recently deceased Norbert Untersteiner, without whom, he acknowledges, his PIOMAS model couldn’t have been created. But as Maslowski quotes from Untersteiner, “A linear increase in heat in the Arctic Ocean will result in a nonlinear, and accelerating, loss of sea ice.” And such non-linear accelerations are of course notoriously tough to pin down: how much will the acceleration accelerate?
Schweiger concludes, “The answer will have to come from fully coupled climate models. Only they can account for the non-linear behavior of the trajectory of the sea ice evolution and put longer term changes in the context….”
Here’s the reason I agree with Neven that the graph with PIOMAS combined with different statistical curves is the best one, and AMEG should use it. In a Malcolm Gladwell “blink” kind of way, you can just cast your eye at this picture of different approaches and grasp the whole situation. I actually agree with one of Schweiger’s points, that natural variability must be kept in mind, if one is trying to make a very specific year of arrival prediction. But one can see in this graph in an instant that while the ice MIGHT do different things, currently its trajectory is towards rapid collapse, and one senses immediately that Schweiger might still be in the middle of his unendingly bland sentence – “this analysis will change the predicted timing of the “ice free summer” but large uncertainties will likely remain…..blah, blah” whenever we might happen to get there.
I’d like to react to Gavin’s first response to my posting #57, since it is relevant to the modelling. I had said that the main forcing for sea ice retreat was from the albedo flip.
He wrote the following:
“Response: This actually doesn’t make much sense. The energy for ice melting is coming from mainly long wave effects and some ocean heat transports, the albedo effect adds to that of course (but less than you might think because of cloud compensation), but a doubling of the albedo effect will not double the rate of melting. And since this is all standard stuff, it is all included in the GCMs, and yet they don’t show the kind of behaviour you are postulating. – gavin]”
It seems to me that modelling has to take account of the physical processes and the data. Gavin disputes that the main driver of the sea ice retreat is the albedo flip, but we are seeing not only polar amplification of global warming but positive feedback, which would not be explained simply by radiative forces and ocean currents. Positive feedback produces a non-linear trend, and the exponential and logarithmic trends fit the PIOMAS data well. This supports my contention that the albedo flip effect could be dominant.
Those who think that there’s nothing to worry about, because sea ice might recover on its own accord, are requiring some negative forcing or feedback effect to come into play, to make the PIOMAS trend line do a U-turn. There is no sign of such an effect. Somebody has described this as waiting for a Unicorn!
David Archer’s argument that there’s nothing to worry about methane is based on the continued existence of the sea ice. If you look at the evidence (as opposed to models) of methane from the Arctic seabed, as collected by Shakhova and Semiletov, then you have to treat the possibility of methane escalation extremely seriously.
So, if we don’t want the sea ice to disappear, we have to do something – we have to intervene. And this is where the geoengineering comes in. Some people argue that to geoengineer would be premature, but do we sit back and do nothing? Unfortunately rescue by emissions reduction is far too late (see Titanic comment 22#). We are forced to find methods of rapidly cooling the Arctic to deal with what appears, from the best evidence, to be a planetary emergency.
This statement by Dr Schweiger isn’t in jest, it is quite correct.
Take the ideal situation, in which we have a series of parallel Earths. It’s only in our Earth that Pinatubo erupted in 1991, there was a mega-El-Nino in 1998, and ocean currents initiated and weather maintained conditions for the sea-ice Crash of 2007. In other Earths these events may have happened at different times or not at all (so far). We don’t have that ideal situation, so we have to rely on models as the next best option. However the principle applies, in free-running* models the events I listed won’t happen or will happen at different times. * I say free-running to differnentiate them from assimilating models.
You mention CCSM4 being even further out if 2010 and 2011 PIOMAS volume is included. In that claim you are clearly unware that the volume losses of both those years are due to specific time-limited incidents, and it is hard to eliminate weather as a cause of those events (as Dr Schweiger points out). So the very years you concentrate on to bolster your claims could actually fit into the paradigm of “Reality is only one realization of an ensemble”.
It is very easy to be deceived by the inherent beauty and self-consistency of your models, plus all the time invested in them. But without evidence of their fidelity to reality how can they be given more credence than short-term extrapolations?
Then why are you paying any attention at all to PIOMAS? Since 2007 it has shown a continued volume loss, over that period the trend in observed thickness, while patchy and sporadic, is rather equivocal. This is no surprise as the thickness reductions implied by PIOMAS are small up to 2009. Again it is only 2010 and 2011 that imply substantial thickness reductions, and so far I’ve not found public widespread data on Arctic thickness that covers these years. So unless you can enlighten me, I see no empirical evidence that strongly supports what PIOMAS is telling us for the post 2007 era.
That said, having read most of the literature on PIOMAS I am confident that the losses of 2010 and 2011 are, on balance of probabilities, real. However I am also confident that free-running models as in CCSM4 are capable of informing debate, even though I personally expect the Arctic to have a September minimum of less than 1M km^2 some time next decade. From my reading of the evidence it’s only if PIOMAS shows another massive Spring volume loss that I’ll be entertaining any suspicion at all that we may see such a state this decade. This is because the ‘early camp’ are missing a major factor, even though most of them don’t know it: That factor is that first year sea ice will continue to grow to thicknesses of around 1.5 to 2m through the winter, so the key issue in whether September can be virtually sea-ice free is how much sea ice can be lost between March and September. The warming being seen during the Autumn and Winter is mainly due to increased heat fluxes from the surface (Screen & Simmonds 2010) due to thinner ice and more open water, so represents a net heat loss to the atmosphere. Whilst the arguments of Abbot, Pierrehumbert and others about cloud radiative forcing may imply an earlier winter low ice condition than GCMs suggest, there is no evidence that this will kick in within a few years. So you’re stuck with a situation in which Winter ice growth remains vigorous and heat losses to the atmosphere increase as the ice recedes.
If the Spring losses are not due to weather but are due to some other factor then they hold open the possibility that increasing and maintained Spring losses could be enough to increase the overall melt season loss so as to leave the Arctic virtually sea ice free by September. Lacking an understanding of what is hapening if we see these losses in three consecutive Springs it is reaonable to begin to suspect that this is not a random process such as weather, but something new. This new factor could be weather but also be part of a new process (the Arctic Dipole being a classic case), or it may be something connected with ice or ocean processes. But three years of a maintenance of a behaviour probably intiated by weather would make the situation seem more analgous to 2007.
The point is, nobody know yet what this Spring and future Springs will bring. Even if this does turn out to be a new factor, that doesn’t bolster the use of extrapolation of trends because a new factor isn’t accounted for by preceding years.
Being right for the wrong reasons is still being wrong.
#62–Reading Tietsche again, I see what you mean, Kevin. However, I think my main point stands (and its essence was better expressed in the inline to your original comment at #31): the perturbations in Tietische aren’t comparable to the decline of 2007. The former magically ‘erased’ all sea ice on July 1; the latter saw it decrease dramatically due to physical ‘forcings.’ Thus the 2007 was not greatly different from ‘what the climate wanted it to be,’ to use the anthropomorphic but useful image from the inline.
I’m certainly repeating others in this thread (& I’ve said it elsewhere before) when I say that the difference between CCSM4 AR4 & PIOMAS outputs is surely far too large to be dismissed as “natural variability” or for such variability to be even a major reason for such a large difference. I should add that I do see the value of models but cannot accept without comment the post’s conclusion “…we need to let science run its course and let previous model-based predictions of somewhere between “2040 and 2100″ stand.”
(I could be sarcy and say that at the present rate of advancement, the science will be hard pushed to reach its conclusions on the date of an ice-free summer Arctic Ocean prior to the event occuring!)
One place in the post that I felt deficient was Figure 4 which lacked a “We are here” marker. (It would be at the top & slightly left of the ’1′ in “…Member Sigmoid Fit 1979-…”) That ‘deficiency’ in Figure 4 reminded me of a graph linked at Neven’s site which has such a “We are here” marker superimposed onto a now-outdated RealClimate graph, only that graph was for Extent not Volume & so importantly compares a measured quantity rather than a model output as is PIOMAS. Extent graph linked here.
Considering ice volumes over the last decade, CCSM4 AR4 is predicting a decline of some 200 cu km pa while PIOMAS models show some 600 cu km pa. That’a a big difference & surely has to be the result of something noticable. (It’s an extra 0.13 zJ pa required to do the extra melt, a figure big enough to get the hardest hearted skeptic to sit up & take notice. Yes! Gather that lot up and bottle it & you could power the entirity of the good old US of A with it! And some.)
That the CCSM4 AR4 are out for Extent as well as Volume got me reaching for the ‘back of my fag packet’ & the naive result may hold arithmetical error but certainly caught my attention.
Half a million less ice extent is a lot more extra open ocean with far lower albedo. My simple model suggests 0.28 zJ pa energy from that reduction.
I do understand the model-speak of the post. Predicting the ice-free summer Arctic Ocean isn’t what drives their effort. Yet work improving the modelling must surley also, with little extra work, a better answer to the ‘ice-free’ question than “natural variability.”
I’m certainly repeating others in this thread (& I’ve said it elsewhere before) when I say that the difference between CCSM4 AR4 & PIOMAS outputs is surely far too large to be dismissed as “natural variability.” I should add that I do see the value of models but cannot accept without comment the post’s conclusion “…we need to let science run its course and let previous model-based predictions of somewhere between “2040 and 2100″ stand.”
(I could be sarcy and say that at the present rate of advancement, the science will be hard pushed to reach its conclusions on the date of an ice-free summer Arctic Ocean prior to the event occurring!)
One place in the post that I felt deficient was Figure 4 which lacked a “We are here” marker. (It would be at the top & slightly left of the ’1′ in “Ensemble Member Sigmoid Fit 1979-2011.”) That ‘deficiency’ in Figure 4 reminded me of a graph linked at Neven’s site which has such a “We are here” marker superimposed on a now-outdated RealClimate graph, only that graph was for Extent not Volume & so importantly compares a measured quantity rather than a model output as is PIOMAS. Extent graph with ‘marker’ here.
Considering ice volumes over the last decade, CCSM4 AR4 is predicting a decline of some 200 cu km pa while PIOMAS models suggest something more like 600 cu km pa. The energy to do that extra melt would be 0.13 zJ pa. That’s a lot of energy & surely has to be the result of something noticeable. (Heck, even the hardest hearted skeptic would sit up hearing a figure like that. Gather it up and bottle that energy and you could power the whole of the good old US of A and some!)
The thought that CCSM4 AR4 is also overestimating Extent as well as Volume got me reaching for ‘the back of my fag packet’ & while the number produced may be wrong somewhere, it certainly gave me food for thought. For half a million sq km less Extent, my naive model gave 0.28 zJ pa.
I do understand answering the ‘ice-free’ question is not the purpose of the models. Yet work improving the models must surely allow a quick & easyish answer that is an improvement to the “natural variability” answer. And I strongly believe the question merits such an answer.
The threats we face from climate change have been amply demonstrated to any sane person willing to take a look at the science. As such, I am puzzled why you think that an additional alarming prediction would suddenly lead humanity to a collective “Come to Jebus” moment and to action on the problem. This is particularly so when the science regarding said prediction remains on the cutting edge and therefore uncertain.
I believe we are facing a force that surpasses inertia–namely collective human stupidity. People will simply refuse to confront a threat if they don’t see a clear path to surmounting it–and preferably one that allows them to keep all their comforts, luxuries and follies. The only force that I know of that can counter that stupidity is human creativity. The few actually intelligent humans will have to bail the rest of humanity out–as they have done before several times.
It seems that human survival now depends on a struggle between the two tails of the intelligence bell curve.
@62 Ice recovers to the “reference run” which does have the greenhouse gas forced decline. Not sure what the confusion is.
@68 Marcel. Did we make a policy statement? I don’t think so. I think we have plenty of good evidence for taking action as it is, but that’s my personal opinion. Whether or not it is helpful to push scientifically unsupported scenarios is indeed beyond my expertise.
To continue the anthropomorphism: My view of the consensus is that the 2007 extent anomaly was where “both the weather and the climate wanted it to be”. Note also that the 2007 thickness anomaly wasn’t as dramatic as the extent anomaly. See: http://psc.apl.washington.edu/lindsay/pdf_files/Lindsay%20etal%202009%20JClim%20-%202007%20follows%20thinning%20trend.pdf
Has anyone asked his group directly if they are relying on information not available to other scientists? Or are they providing somewhat laundered data? It’s been a long, long time since the first “Gore Box” data release.
I wonder if the modeling by the Navy Postgraduate School may be relying on some undisclosed thickness data. (From a military perspective, you’d have to hope so! but for science, not.)
The language is subtle; is the data all available if you know who to ask?
Here are two of the many you can find with Scholar:
“The skill of the model is examined by comparing its output to sea ice thickness data gathered during the last two decades. The first dataset used is the collection of draft measurements conducted by U.S. Navy submarines between 1986 and 1999. The second is electromagnetic (EM) induction ice thickness measurements gathered using a helicopter by the Alfred Wegener Institute in April 2003. Last, model output is compared with data collected by NASA’s ICESat program using a laser altimeter mounted on a satellite of the same name.
The NPS model indicates an accelerated thinning trend in Arctic sea ice during the last decade. The validation of model output with submarine, EM and ICESat data supports this result. This lends credence to the postulation that the Arctic not only might, but is likely to be ice-free during the summer in the near future.”
“The model comparison is made against the most recently released collection of Arctic ice draft measurements conducted by U.S. Navy submarines between 1979 and 2000.
The NPS model indicates an accelerated thinning trend in Arctic sea ice during the last decade. The validation of model output with submarine upward-looking sonar data supports this result. This lends credence to the postulation that the Arctic is likely to be ice-free during the summer in the near future.”
How about the British and Russian and French Navy submarine fleets? — have they been asked to provide researchers with any Arctic ice thickness data?
How about the oil and gas companies that are starting to explore the Arctic? Is there a point where commercially proprietary data should be released in the public interest?
Well, it’s pretty hard to argue against ‘the ice is where the climate wants it to be…” It is where it is. :)
Nor am I trying to equate 2007 with removing all the ice per Tietsche’s model runs. What I am trying to decipher are the physical mechanisms that make Tietsche’s results possible.
It seems logical that any large perturbation in ice extent is going to lead to certain mechanisms – Chris R details a couple of them in #75. Indeed after 2007 we *did* see an upwards blip in extent. If sea-ice extent were our only measure or concern I would say that Tietsche was a very good explanation.
BUT … Tietsche also says that volume recovers just as quickly as extent. This is where (for me) the story falls apart. If volume had blipped upwards following 2007 and then resumed its downward trend there would be no argument (from me) on the validity of the model.
Instead we see volume ignore the large perturbation. This indicates *something* – a flaw in the model, a flaw in our volume data collection (PIOMAS), a ‘perfect storm’ of weather following 2007 (??), or a basic misunderstanding of the sensitivity of sea-ice volume to climate.
My own amateur suspicions are that Rampal and Kay have already highlighted two of the major model failings in regards to sea-ice modelling: ice mechanics and kinematics and cloud forcing/feedbacks.
I’m not arguing that Tietsche is wrong vis a vis ‘tipping points’ – I’m arguing that climate *is* driving sea ice loss and that the model Tietsche used lacked the proper mechanisms to reliably extrapolate forwards. What would the model runs look like if the deficiencies Rampal and Kay noted were addressed? Until that time I can only regard Tietsche as interesting, not definitive or authoritative.
“The first of its kind ICEX survey has proved to be of great value to both NASA and NRL in terms of better understanding the capabilities of airborne and satellite based instruments to measure varying ice types. This will aid in achieving a resolution that is adequate to minimize the degree of uncertainty in models that forecast future conditions and for monitoring decadal variability.”
Title : The Dragon Eyes the Top of the World: Arctic Policy Debate and Discussion in China (China Maritime Studies, Number 8, August 2011)
Corporate Author : NAVAL WAR COLL NEWPORT RI CHINA MARITIME STUDIES INST
Report Date : Aug 2011
“Abstract : The Chinese are increasingly interested in the effects of global climate change and the melting of the Arctic ice cap, especially as they pertain to emergent sea routes, natural resources, and geopolitical advantage. China seems to see the overall effect of Arctic climate change as more of a beckoning economic opportunity than a looming environmental crisis. Even though it is not an Arctic country, China wants to be among the first states to exploit the region’s natural resource wealth and to ply ships through its sea routes, especially the Northwest Passage….
… This study considers at some length the discussions and debates on Arctic issues, mainly in Chinese-language scholarly journals but also in journalistic and diplomatic Chinese-language discussion. The study is a report on China’s sometimes-contentious debates and discussions of the issue, an account that hopes to convey something of their extent, complexity, and flavor while China works out its Arctic policy and prepares for its future position in and regarding the Arctic. It also offers some foreign policy recommendations for the United States.”
Lack of empirical evidence in not proof that no evidence exists.
It is also unlikely that first year ice will continue to grow to thicknesses of 1.5-2.0 m through the winter when the temperature of the Arctic Ocean is steadily increasing, wind speeds are increasing, the first year ice is increasingly briny and brittle and easily broken up, and when there appears to be an increasing tendency toward longer and steeper negative AOs, meaning that warmer air and water will be entering the Arctic Sea via the North Atlantic for extended periods of time.
If I understand AMEGs argument correctly, it is that we need to find engineering solutions in the Arctic to alleviate an effective emergency (on a basis of precautionary principle at very least) posed by possible majority loss of sea ice or escalation in methane release. I’d be rather surprised if they weren’t also recommending to resolve atmospheric carbon dioxide burden as well? (quite a few people are already correctly calling for that)
I happen to generally agree with them – in my view the situation is somewhat like a car heading for a cliff with faulty brakes. While we do need to fix the brakes (carbon dioxide), the imperative ought to be on stopping the vehicle (by any means we can) before we drive off the cliff (catastrophic climate change). The brakes should have been fixed a long time ago now. Fixing them now won’t necessarily leave us time to avoid the cliff (inertia in the system).
For the submarine data, I think that whatever USA has collected is more or less what there is.
USAs submarines, in order to hold targets deep inside Soviet/Russia at risk, did routinely hold station under the arctic ice for extended periods, and the ice above had to be something they could penetrate, so they measured it.
English and French submarines have not, as far as I know, held target at risk from below ice on a routine basis, so whatever data they have is probably very sparse, they also have very few submarines in total.
Soviet/Russia has to my knowledge never operationally held targets at risk from below ice, there being no need to do so, as their targets were reachable from positions in the Atlantic and Pacific.
I have no idea if Soviets atomic icebreaker(s) collected data which could be useful, one of them is still in action I belive, so call them and ask…
Comment by Poul-Henning Kamp — 14 Apr 2012 @ 2:24 PM
I agree with your assessment of Tietsche et al in #62. The finding with regards volume being apparently at odds with the volume loss suggested by PIOMAS seems relevant to Tim Lenton’s recent pronouncements. http://www.newscientist.com/article/mg21328583.900-arctic-sea-ice-may-have-passed-crucial-tipping-point.html
A point Lenton has been making is that after 2007 instead of a recovery to a pseudo equilibrium state there has been a continuation of the greater seasonal cycle. If we are to accept the PIOMAS volume loss, this adds to Lenton’s point.
As I’ve blogged recently I still think Boe et al presents the most comprehensive model mechanism that could explain the failure of models to reproduce the observed change. The Kay et al paper you link to specifically refers to the occurrence of stable summer conditions in one model. While Rampal et al may not explain the difference so much because of the observed difference between recent volume and area transport through Fram. There is no trend in net mass of ice transported through the Fram Strait. http://www.ifm.zmaw.de/research/remote-sensing-assimilation/sea-ice/sea-ice-volume-flux/
Although due to increase of speed of transport through Fram, area flux has increased in recent years (Smedsrud et al, 2008). So whilst the ice is more mobile because it’s thinner, the fact that it’s thinner means less volume is transported, the two factors balancing to give no increase in volume transport.
Seriously, from what we know, so many other nasty things will have happened before a methane burp becomes an issue.
The “methane emergency” is like a movie car-over-cliff-explodes scene.
In reality cars don’t explode; the crash kills the passengers anyhow..
But imagine there’s a decision to cool the Arctic — well, what tactics might cool the Arctic?
– forbid aircraft in the stratosphere, keeping it dry, removing contrails
– forbid diesel shipping so black carbon isn’t deposited on the ice
– supplement nutrients that limit methanogens and photosynthesizers (stir up sediments? Or are we flushing excess nutrients from the rivers around the Arctic?)
– increase the emissivity of the Arctic ocean or sea ice below a clear dry sky?
– warm the upper atmosphere so it radiates more heat away? As the stratosphere has been cooling, we get Arctic ozone holes ….
– halt fossil fuel use and invest in alternatives as fast as possible
From what I understand, the geoengineering being considered is to spray water or salt water into the atmosphere to increase the reflectivity of clouds. The method is being worked out by Dr. Stephen Salter.
Methane levels above the Arctic are frequently recorded above 1,900 ppbv.
What controls primary production in the Arctic Ocean? Results from an intercomparison of five general circulation models with biogeochemistry
Models show similar features in terms of the distribution of primary production
However, physical factors controlling this distribution differ between the models
Models disagree about which factors, light or nutrients, control present productivity
Wait, dagnabbit, this is one the submariners certainly can answer, if they don’t already have the information. Do the various Navy submarines sample the water they’re going through regularly? (And if not wtf not, eh?) So they should be able to answer the question that paper stopped with, and this would be a major clue toward _bio_engineering the Arctic:
“The intercomparison between models finds substantial variation in the depth of winter mixing, one of the main mechanisms supplying inorganic nutrients over the majority of the AO. Although all models manifest similar level of light limitation owing to general agreement on the ice distribution, the amount of nutrients available for plankton utilization is different between models. Thus the participating models disagree on a fundamental question: which factor, light or nutrients, controls present-day Arctic productivity. These differences between models may not be detrimental in determining present-day AO primary production since both light and nutrient limitation are tightly coupled to the presence of sea ice. Essentially, as long as at least one of the two limiting factors is reproduced correctly, simulated total primary production will be close to that observed. However, if the retreat of Arctic sea ice continues into the future as expected, a decoupling between sea ice and nutrient limitation will occur, and the predictive capabilities of the models may potentially diminish unless more effort is spent on verifying the mechanisms of nutrient supply. Our study once again emphasizes the importance of a realistic representation of ocean physics, in particular vertical mixing, as a necessary foundation for ecosystem modeling and predictions.”
Hell, the petroleum companies probably also have this kind of water contents data collected, for any area they’re interested in, whether they’ve looked at whatever samples they collected or not.
Isn’t this a place where rather than just improving the models, getting hold of actual physical and biological data about the ocean over time will help?
The Arctic has been used for decades by submarines doing their cold war best to know everything they might possibly need to survive and outlive their opponents. This kind of data about currents and mixing and water chemistry and even plankton samples just be in the various Navies’ systems somewhere, if only as raw samples on dusty shelves.
‘am puzzled why you think that an additional alarming prediction would suddenly lead humanity to a collective “Come to Jebus” moment’
Your puzzlement is your own doing, since I didn’t say that.
‘and to action on the problem’
What I said was that “the later the end of Arctic ice comes, the more people can rationalize not acting”. If you manage to grasp the difference between what I wrote and what you have, perhaps you will become less puzzled. Notably the people whose rationalization in this area most matters are people in positions of political power.
‘The few actually intelligent humans will have to bail the rest of humanity out–as they have done before several times.
It seems that human survival now depends on a struggle between the two tails of the intelligence bell curve.’
I expect someone on the high end of the curve to notice the contradiction between those statements. And I don’t think either of them are accurate.
“Did we make a policy statement?”
You made statements about policy; I quoted from them. Regardless of any quibble about whether they are policy statements, they are not scientific statements about climate or ice.
“push scientifically unsupported scenarios”
Like Ray you project on me a position I did not express. I referred to plausible scenarios … plausible on the basis of the available evidence. Such plausible scenarios are supported by science, even if they haven’t been proven by science … but science isn’t in the business of proof or final absolute authority … and if that’s what it were to take to be scientifically supported, then science would be useless for policy … but fortunately is not. Considering only the science, there is some earliest plausible date of an ice free Arctic summer, and that date should be of considerable interest to policy makers, and that date, being a boundary, has a special status, purely within a logical and scientific framework.
I’d say as the meteorologists can predict some weather with over 50% (Bayesian) accuracy to a short period of future there might be a (Bayesian) solution of the case being P = NP. I’m not not saying the solution is found out very early in the process but at least it may then add to the list of problems that belong to the set “P ≠ NP” or “P = NP”.
Lack of empirical evidence in not proof that no evidence exists.
Of course not, but without observational evidence that the PIOMAS Spring volume losses are real, their reality has to be claimed with caution. I think they’re real, based on my reading of the literature about PIOMAS. But what is observed always takes precedence over what I think. PIOMAS is the best proxy for sea ice volume we have, but it is only a proxy, not a direct measurement.
It is also unlikely that first year ice will continue to grow to thicknesses of 1.5-2.0 m through the winter when the temperature of the Arctic Ocean is steadily increasing…
Yes but how rapidly will this process proceed? Bear in mind here that most of the October to March warming is due to surface heat fluxes. Screen and Simmonds state in their abstract that: “Arctic warming is strongest at the surface during most of the year and is primarily consistent with reductions in sea ice cover. Changes in cloud cover, in contrast, have not contributed strongly to recent warming.”
So there is little evidence of the cloud radiative feedback that may keep the Arctic temperate in future being a major player now. And changes in ice cover are driving most of Arctic temperature amplification.
Thus the claim that Arctic warming as the ice recedes will present a risk of stopping ice growing from October to March is a circular argument. The very warming that is supposed to impede ice growth over Autumn/Winter is a process whereby the Arctic is shedding heat gained by ice loss. So as it intensifies more of the energy gains of the year will be lost to the atmosphere and thence to space.
While I respect your views and you are clearly better informed on the detailed science at issue here, I beg to differ on some not insignificant points.
“Being right for the wrong reasons is still being wrong”
Clearly being right for the wrong reasons is as a matter of logic, grammer, causality etc, clearly BEING RIGHT, even if this decision was reached by a flawed process. If you think about it, in science it cannot be otherwise, as there is no such thing as a final flawless infallible theory of everything to guide our thinking. All science is a MODEL of reality, and all models are wrong. And whatever decisions we make, regardless of the correctness of our reasoning, we are left with the consequences of that decision, not the consequences of our reasoning.
Secondly, your “other earths” are a thought experiment – another model – like the many worlds interpretation (http://en.wikipedia.org/wiki/Many-worlds_interpretation). The Universe could be completely deterministic (Schroedinger’s Equations are) while having the appearence of randomness.
The relationship to ensemble models is that the underlying physical processes are chaotic – highly sensitive to the initial conditions. We hypothesise (& it seems reasonable) that we can capture the range of possible outcomes if we could somehow run “reality” with slightly varying initial conditions. This concept is a model, a thought experiment. It is NOT reality. The models must somehow be validated in the application of interest to be useful. I accept GCM’s have been validated for projection of global climate change, but their record on the cryosphere is woeful.
Thirdly, I don’t know the history of PIOMASS. As I understand, it attempts to estimate ice area, thickness and volume. As it is largely a process of statistical intepolation, with limited projection, I assume it has been subject to considerable experimental validation. Please tell me if this is not the case!
Finally, you seem to be suggesting that unexpected weather was responsible for the low ice events of 2007, 2010 & 2011. As far as I know El Ninos like that of 2007 do occur in climate models (not that specific one), as does other large scale weather phenomena. The whole point of ensembles is that if some random sequence of weather events can produce the low ice events, this should be seen in some models and so be included in the “confidence intervals” of the ensemble. This is the variability issue I was referring to. If I am reading the output of the ensemble models correctly, none of them suggest the possibility of the recent low ice events.
“Reality is only one realisation of an ensemble” – a wonderful quote, but neglects a crucial point. We want to know which realisation we’re in!
The argument at its simplest is that since there are individual model runs in the CCSM4 ensemble that are just about as bad as our current reality, we can’t rule out the chance that reality will return to the CCSM4 ensemble line – i.e. the decline will slow, and the Arctic will be summer ice-free in “only” 2040-2050 or so. Even on the face of it, this seems wrong. Did the most pessimistic individual runs really subsequently return to the mean of the ensemble? Or did they remain below it for the remainder of the run?
http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/validation/Fig13b.png (looking at CCSM 20th & a1b) suggests the latter. These are presumably the worst individual runs, and they do indeed match PIOMAS extent/volume up to 2006, though not beyond. These runs zero out in ~2040, noticeably before the bulk of the ensemble. Even if the model is correct in all particulars, then if the real Earth is following a similar realisation, logically we too will come off worse than the ensemble average!
If you take the view that CCSM is correct, or nearly so, then in order to predict the real world, we need to work out which realisation is closest to reality. One approach could therefore be to break the ensemble down into its individual members, and exclude those one by one as “reality” shows us which members she’s more likely to be following. Averaging together the remaining runs – the runs that haven’t yet been ruled out by inconvenient data – seems like it would give a more accurate prediction.
However, philosophically that approach rests on an underpinning assumption:
our reality genuinely is the worst of all possible worlds and hence we “just happen to be” tracking the most pessimistic individual model runs. This goes against the Copernican principle that we should expect to follow a kind-of-average trajectory.
An alternative approach could be to take the shape of the CCSM4 ensemble curve, which is kind-of-sigmoid, and then scale that to fit the real data. That thus assumes that reality is following an “average” trend relative to what’s expected based on AGW forcing, but that the model has underestimated the sensitivity of the response to forcing. That too would
lead to a prediction substantially more pessimistic than the current ensemble mean.
Both of those approaches seem to me to be more scientifically justifiable than just taking the ensemble mean at face value.
RE: “Reality is only one realization of an ensemble”
Well, that’s kind of the point, isn’t it? If a model is going to purport to actually represent the real world, reality must be a reasonable member of the ensemble. If not, the model cannot reasonably be used as a basis for prediction. This writeup presents CCSM4 as a reasonable model to use for prediction (if time-shifted 20 years), but where is the CCSM4 ensemble member in which September ice volume has dropped 75% between 1979 and 2011 (even shifted 20 years)? The same goes for the model used by Tietsche; none of the ensemble members show a September ice volume drop which comes close to matching reality.
The writeup justifies this trust in models by linking to a CCSM3 model realization. OK, reality is possibly acceptable as an extreme realization of that model (though the graph isn’t terribly convincing, given the extent difference), but why should this imply that I should accept the results of other models which don’t include reality as possible realizations?
How is it that an old, low resolution model like CCSM3 yields results which match the observed ice volume so much better than the latest models which one would think ought to do much better? I think this is likely because ice volume variations likely depend strongly on the model’s stability under perturbation, and multiple errors in this parameter with different signs can end up canceling each other out and yielding plausible stability. At least some versions of CCSM3 are known to be unstable under perturbation. Also, projection of fields onto a coarse grid yields diffusion/mixing-like terms, which could compensate for parameterizations which yield too little mixing. Obviously one wants to correct all the errors, but for prediction it is still necessary to use a model which reasonably matches reality.
There are only a few reasonable explanations for the persistence of the observed anomalous amounts of sea ice. Either there’s a large decadal-scale internal variability driving it, such as a large pseudo-cyclical increase in deepwater formation, or the Arctic Ocean is near marginal stability under perturbation. See Merryfield for how the decreasing stability increases persistence. I’m not buying the writeup’s implication that we’ve been throwing nothing but sixes for the past seven years.
Unfortunately, I’m still not seeing it. I’ll post thoughts and await correction:
This post is missing a figure. All of the CCSM4 runs and PIOMAS should be displayed in a figure with a single time line. The 20 year shift in figure 3 primarily serves to hide CCSM4′s deviation from reality’s “run”.
Figure 3′s lowest CCSM4 run has a minimum in 2011 or before of near triple the ice that PIOMAS has in 2011. Either PIOMAS is way off, CCSM4 is way off, or the current decline in sea ice is a series of ever-increasing extreme outliers. In order to suggest that reality is a bunch of extreme outliers, wouldn’t you have to provide mechanisms by which reality’s “run” has been affected? Saying reality is an unbroken series of increasing but nearly independent high sigma events requires incredible evidence. An F&R2011 style analysis might have been an appropriate addition to this post. Why is PIOMAS so far below all CCSM4 runs? Is CCSM4 capable of duplicating PIOMAS? Taken at face value, Fig 3 manifests into a prediction that sea ice will increase, with expected values in 2080 25% above 2011 values.
PIOMAS can run in forecast mode. Would you please provide a few runs for 2012-2019? Wouldn’t that avoid the extrapolation issue? Certainly 2012 would be a reasonable data point. With 3-8 years left in the theoretical decline, even one year’s data can make a huge difference in probabilities.
We also have Maslowski’s model supporting the PIOMAS extrapolations. Data, extrapolations, and model all agree, yet the OPs left the most famous modelling result for sea ice out completely. Why is Maslowski’s model so flawed and CCSM4 so good even though reality seems to be following Maslowski’s model?
Fig 1 bears mentioning. The linear trend hits 1k around 2030, with the current situation being just a huge dip in the road. That sounds reasonable if supported with analysis. Of course, it still makes “2040-2100″ look way optimistic.
In summary, there is a huge spread in model estimates for 1k, from 5 years (Maslowski) to no reduction at all through 2100 (CCSM4). The OPs gave no rationale for selecting any particular model, and the model they chose to display was rejected in their final estimate. I would have liked some comparison of the credibility of each model or some analysis adjusting for natural variability. Be that as it may, if I accept the OPs’ contention that coupled models and only coupled models provide decent predictions, then I conclude very tenuously that 5 years +- 3 years is the best estimate, as Maslowski’s model suggests, while noting that “not in this century”, as suggested by CCSM4, could be someone else’s estimate. Conversely, if I reject their contention, the best data we have extrapolates to 1k in 3 (exponential), 8 (sigmoid), or 29 (linear) years, with the best fits for the exponential and sigmoid extrapolations. Using both model and data, my guesstimate for 1k is 3-8 years with a fat tail out to around 30 years and no upper bound as the ice pile above Greenland and Canada could become pretty stable at 2k, for example.
RE: “Reality is only one realization of an ensemble.”
It is also possible that reality is not represented in the ensemble at all. Using 30 years of data to predict forward 90 years if difficult in and of itself, let alone projecting ice values much lower than experienced during the dataset time frame. Jim hits a little bit on this with his guesstimates of 3 years to stable at 2k, thereby never reaching the 1k threshhold.
It appears that the models are reasnable good at predicting ice in the open watre areas, but have much difficulty in the semi-enclosed areas.
Peter Ellis: “We want to know which realisation we’re in!”
Sorry, Peter, but this is a fundamental misunderstanding of the purpose of scientific modeling–which is to attain understanding of the system being modeled. The understanding in turn provides a basis for predictions of future behavior.
#93 Hank Roberts: Does that mean you rule out the possibility Shakhova and Semiletov are correct to estimate 50GT of methane is eligible for abrupt release? Or does it mean you would only assess “emergency” at the point it actually does release on a big scale (ie much bigger than the 1km plumes discovered last year)?
I agree other things are also going on – letting any positive feedback process get established is a mistake.
Clearly being right for the wrong reasons is as a matter of logic, grammer, causality etc, clearly BEING RIGHT, even if this decision was reached by a flawed process.
Would you toss a coin; “heads this decade, tails later” and claim you were ‘right’ if your coin throw happened to agree with what transpired? There’s a more serious consequence of being right for the wrong reasons: If there is a massive drop to well under 1M km^2 and you interpret this as evidence of a tipping point, whereas what happened was a succession of 2007-like atmospheric set ups, any prognosication will be shown wrong when in the following years the ice grows back and the condition doesn’t maintain itself. It really does matter whether your workings are correct because reality doesn’t give a hoot for our reasonings, correct workings should be based on evidence and reasoning with the goal being understanding, not being right.
Secondly, your “other earths” are a thought experiment – another model – like the many worlds interpretation…
No, they’re an analogy, and the underlying point is sound. Events like the ones I list were the outcome of random priming events leading to the occurence of the final event, why didn’t the 1998 El Nino happen any number of years before or after, why did it occur at all? This isn’t pointless theorising, it has a direct bearing on what Dr Schweiger is saying. And what he is saying is correct; it is only in our ‘realisation’ that the events I listed happened when they did, and had the cumulative impact they have had playing their role in the succession of events we have observed. However see the end of this reply for my view on whether we’re simply on a single realisation.
Pan Arctic Ice/Ocean Modeling and Assimilation System. It is a model of the ocean and ice over a specific domain covering a large part of the Arctic region. That’s the physics core – the ice and ocean. Into this core is introduced data covering SSTs, ice concentration, and atmosphere. The atmosphere data that drives PIOMAS is taken from ‘reanalysis’ AFAIK they use NCEP/NCAR, but they could use other systems. So the ice ocean physics model can be considered a black box into which you put the atmospheric factors, the box then spits out the response of the ice and ocean to the atmosphere. This is because the atmosphere is the dominant factor.
From my reading I interpret 2007 as a specific outcome of various processes. http://dosbat.blogspot.co.uk/2012/04/musings-on-models.html
The Spring volume loss in 2010 does seem to be associated with a persistent pattern of high pressure, which doesn’t seem to be the Arctic Dipole (NCEP/NCAR), so as yet I haven’t figured out how this caused the ice volume loss reported by PIOMAS. As for 2011, I am unable to explain it.
I am awaiting this year’s Spring volume data from PIOMAS to see what happens. If there is no similar volume loss then I’ll put those years down to ‘weather’. However if we have a similar profile of volume loss as in the preceding two years then random variability looks very unlikely and I’ll be veering to the following viewpoint – that something new and radical has happened in the seasonal cycle of sea-ice loss, a new factor that in principle could have the power to make a virtually sea ice free state in September plausible this decade. I await the data before making any decision.
Those projections are detailed in Zhang et al, 2010 “Arctic sea ice response to atmospheric forcings with varying levels of anthropogenic warming and climate variability.” http://psc.apl.washington.edu/zhang/Pubs/Zhang_etal_2010GL044988.pdf I think you may be surprised at the results, you may want to peruse that link (the first link) before reading further. I recommend checking out 2025 and 2035.
The way the future projection is done is they use randomly shuffled past years of weather (NCEP/NCAR) and add those to a ‘spine’ of warming from GCM projection. If you check the first link in my reply to Bruce Tabor above you’ll find some comments on this study at the end of that post.
However your comment on Maslowski has combined with my scanning the papers Hank linked to earlier in this thread; trend extrapolation using both PIOMAS and NPS are being used to assert that the Arctic is on a fast track to seasonally sea-ice free state. I’ll suspend my cynicism of extrapolation for the moment by accepting that the volume loss in PIOMAS and NPS seems inconsistent with what I’ve seen of GCMs.
Both NPS and PIOMAS retrospective runs use ‘observed’ data for their atmospheric components. PIOMAS seems to use NCEP/NCAR, NPS uses ECWMF. Maslowski has stated resolution is a major factor in the ‘early ice free’ implications of volume loss. PIOMAS “has a horizontal resolution of 40 km X 40 km, 21 vertical ocean levels, and 12 thickness categories each for undeformed ice, ridged ice, ice enthalpy, and snow.” NPS “is configured using a horizontal, rotated spherical grid covering 1280×720 cells at a 1/12 degree (approximately 9km) resolution. It has 45 vertical layers” in the ocean. So whilst Maslwoski has asserted that resolution is a key factor it doesn’t seem to be the case when PIOMAS is considered, NPS is 9km square, PIOMAS 40km square.
Going back to data assimilation. Zhang et al 2010 reveals inflection points when going from historic NCEP/NCAR to a combination of GCM temperature spine and randomly shuffled NCEP/NCAR weather to represent a warming trend with weather variability. The authors note that randomly shuffling the ‘weather’ in this way will neglect contribution of trends in weather that are reinforcing the loss of ice. Part of the inflection may well be due to the GCM projection. However what both NPS and PIOMAS have in common is the assimilation, and their volume outputs have both been argued to imply an early loss of sea-ice.
So how much do changes in the Arctic atmosphere play a role in the loss of sea-ice volume and the apparent failure of the GCMs to reflect the current volume loss? Am I in a rut when I point the finger at the Arctic Dipole?
Note, as always; I know nothing, I post examples of what I find, but likely more interesting work can be found that I didn’t happen to stumble on looking with Scholar. (Those two are MA thesis papers, with Maslowski as advisor, from recent years; they can’t be the whole story of what(ever) the Navy knows.)
Douglas says: “… the 1km plumes discovered last year”
Who has seen a first hand report of “1km plumes discovered last year”?
It’s not in their published work, that I’ve found.
Igor P Semiletov et al 2012 Environ. Res. Lett. 7 015201
Received 5 August 2011, accepted for publication 6 December 2011
Published 4 January 2012 http://iopscience.iop.org/1748-9326/7/1/015201/article
discusses methane from coastal erosion — recent carbon, not old carbon.
“… we plan to obtain new data to answer the following overarching questions.
… How much CH4 could be released to the atmosphere from the ESAS due to degradation of sub-sea permafrost and decay of seabed deposits? What is the current state and projected future dynamics of sub-sea permafrost?
… study will require multiple year-round exploration campaigns, including drilling of sub-sea permafrost to evaluate the sediment CH4 potential ….”
Ray: “I believe we are facing a force that surpasses inertia–namely collective human stupidity. ” Humans are crawling out of the stupid morass for millenias, it goes in cycles, a true one, not the accuweather climate cycle a la Bastardi. Of which wars seem to push us further on the creeping edge of better ways of killing, that insanity side effects, the crumbs pushed us forward, some say the space age was different, but it was born from the cold war. I would say its hopeless when all scientists pack up their goods and rocket away to Alpha Centauri, but thanks to your colleagues and science, there is always the luck of humans to count on, surviving millions of years, by being clever or dumb, happenstance is our middle name, there is always a chance will get it right.
The methane discussion above fascinates, I dont think we know everything about it, since a lot of it is under sea ice at bottom of arctic ocean. There is no certainty here, there is only knowledge that it will increase in concentration. I read a whole lot of discussion but very very little observing. It should be the opposite, often we read peer review papers on the subject, they are mainly based on short term observations and data acquiring. I rather we discuss the numbers, the actual data out there. However little it may be.
Neven 1900 ppb Arctic number is a start, surely there are seasons , variations , regions with more CH4 than others. All is related to sea ice almost being completely open like 2007 or it being frozen up, rock solid as in March. Lets see how much methane shows up , when and where , if there is such data, that is a crucial discussion needed before conclusions are thrown out, understanding the Arctic requires data from here.
Dr. Semiletov was interviewed about the vast plumes of methane:
In an exclusive interview with The Independent, Igor Semiletov, of the Far Eastern branch of the Russian Academy of Sciences, said that he has never before witnessed the scale and force of the methane being released from beneath the Arctic seabed.
“Earlier we found torch-like structures like this but they were only tens of metres in diameter. This is the first time that we’ve found continuous, powerful and impressive seeping structures, more than 1,000 metres in diameter. It’s amazing,” Dr Semiletov said. “I was most impressed by the sheer scale and high density of the plumes. Over a relatively small area we found more than 100, but over a wider area there should be thousands of them.”
I generally collect everything I can find by Shakhova and Semiletov on my blog, so you can see it at this link:
its really good of real climate to address this burning issue. This article certainly addresses the exaggeration in the political pro green blogs, media and informed webistes on which if real climate was not here I would be presuming those artciles to be true.
Slickly written blogs and sites against the wording from here make me realise how easy is it for a not skeptical enough mind (scientifically that is before you all jump on me)to take the bait and start thinking that doom in accelerating when indeed its just that as real climate have been stating for ever makre sure your time series is long enough to flush out the natural variability.
There has been some criticism of this statement. But, it is not the first time I’ve heard it. Though I went the observational route, I did get some training from Josh Barnes, one of the better astrophysical modelers. And it is true that systems which are sufficiently non-trivial to require a concerted modeling effort generally have stochastic characteristics. Close three body dynamics in many-body Newtonian simulations, for example, have to be captured and treated statistically. This is fully justified because reality does act like a member of an ensemble at this level. And, modeling in this manner gives us an opportunity to learn.
I’d like to commend Axel and his co-workers for displaying a comparison with ice volume. So many authors stick with extent alone despite the availability of PIOMAS.
Which is better? Including more physics and seeing models depart from observations or sticking with old models even though it is known they are lacking? I’d say the former because further iteration will tell us what is lacking in our understanding.
#111–”I think the second point may be more suitable for judicial review rather than peer-review.”
Which judiciary? According to those who talk about this ‘pressure,’ it was coming from various national governments. So who has jurisdiction? The International Court of Justice hasn’t been accepted by all parties (non-signatories include, IIRC, the US.) Who else is there?
There is no question about the newer thinnest of the Arctic Ocean sea ice by mere observations in situ and from satellite pictures, I have found dozens of examples, so I am a bit perplexed by claims otherwise.
I don’t think its satisfying many when one claims something without multiple back ups, secondary observations apparently trivial may deny one claim or another. Natural variations are a given, a non argument, I suggest to look up very carefully at the Arctic ocean proper, with high resolution shots,
Look very very carefully at Jpeg full resolution product late March as on the second article down on my blog, observe the white streaks streaming all over the place, these scream out as something newish.
How we square that with the claim that ice is somewhat thicker than a few years ago is difficult.
By the way the 3rd article deals about El-Nino, again witness the power of observing over simply mere thought and analysis.
Here’s a bit of Fawlty Language doggerel that illustrates how chi-by-eye might see a sigmoid but in fact the function is linear. A periodic function with added noise goes along for a while and then dips linearly towards zero. The “annual” minimum slips below zero but owing to noise pops up again giving an impression of a gradual approach to zero. Plotting the “annual” maximum with the same sigmoid shifted up shows that this is an illusion. The script should also run in IDL.
for i=0,119 do if i lt 40 then c(i*12:i*12+11)=4.+d(i) else c(i*12:i*12+11)=(40.-i)*3./55.+d(i)+4.
f(where(f lt 0.))=0
plot,f, title=”Annual minimum”
Re: possible methane releases, following up on some of the previous comments, Gavin Schmidt’s reply to one of them, etc.
I personally find something like the following arctic methane scenario quite astonishing to contemplate, and please take note that it neither goes against anything said recently by David Archer here at Real Climate, nor posits any mechanism that is not currently already activated towards change, and is entirely based upon already observed flux rates, conditions, etc.
Let’s imagine that just a small fraction of only the NON-HYDRATE C store around the ESAS submarine permafrost were released as methane rather quickly, either in one season, or even episodically over two or three years. Let’s make it just a mere .45%. This would be equal to 3 Gt methane. (3Gt CH4 = 2.3 Gt C, and 2.3 Gt C = ~.45% of 500Gt C, the amount estimated to be around the ESAS submarine permafrost [Shakhova, 2010]).
This is a quite credible scenario. It is certain that there are already releases coming from this source, and that there is currently significant deterioration of the state of this carbon store from influxes of warming waters, lost ice, etc. Current methane fluxes recorded in the water column from around these methane hotspots are >1000x those expected from the observed atmospheric anomolies, so considerable methanotrophic activity could already be activated, making irregularities of microbial consumption potentially even capable of such a release on its own. An estimated 3-5% of ESAS submarine permafrost is currently estimated to be perforated with taliks and degraded [Shakhova, 2010], and extrapolation from current hotspot releases would actually equal ~3.5Gt/yr [Shakhova, 2010].
A pulse of 3 Gt CH4 doubles the methane increase since industrialization: we have increased methane by about +157% (700ppb + 1100ppb= ~1800ppb), with abundances being ~1.9Gt (pre-industrial) + 3Gt = 4.9Gt CH4 (current). With best understanding of all indirect effects, this 3 Gt has added ~1W/m2 [Shindell et al, 2008]. Thus, this modest methane pulse would add quite quickly about +62% to all the increased radiative forcing since industrialization.
Further, spreading it over a couple of years wouldn’t make all that much difference: the feedback effect for methane is a ~ -.2 loss rate for each +1% of methane emission rate, which holds for up to about 33% increase in emission rate. (After that, I believe the negative loss rate increases further – I think Gavin has written on this and could explicate this easily). Roughly, the release would constitute a ~+500% change, so the pulse should, I believe, last for something like double the lifetime, or more, something like two decades or more. In any case, it would last long enough that I suspect it might cause Much Ado.
RE: “Reality is only one realization of an ensemble”
If you have a model which is consistently wrong in one direction, the conclusion is that your model is either incomplete or wrong. If the model works for many other things (GCMs) you can still confidently use a consistent offset to estimate the future till you figure out how to improve the model.
This point emphasizes the dichotomy between the two uses of models, for forecasting and for understanding.
“They [AMEG] don’t yet get the science, as Gavin pointed out above.”
“Seriously, from what we know, so many other nasty things will have happened before a methane burp becomes an issue.”
The accusation that AMEG does not “get the science” is a serious accusation, since AMEG claims to be driven to its conclusions by the best available evidence, both on sea ice and on methane.
AMEG’s Peter Wadhams, a professor of Ocean Physics at Cambridge, is the UK’s top expert on sea ice. He explains that the sea ice is thinning at an accelerating rate, as the Arctic Ocean warms. The ice can get thinner and thinner while the extent remains roughly constant, as has happened since 2007; but this can’t go on for many more years as shown by the PIOMAS data. At some point the extent of the ice has to collapse. But the thickness and melting of the ice is not uniform over the whole Arctic, so some residual ice will probably remain north of Greenland and around some of the islands. Thus the sea ice volume will not fall straight to zero on the PIOMAS graph, but curve round to the right. However the sea ice September extent can be expected to fall to a much reduced level by 2015, and possibly earlier – even this year is on the cards.
The main heat flux for the warming ocean is now coming from the albedo flip effect. Thus if the decline in extent doubles, this albedo flip warming effect doubles.
[BTW, I made a careless mistake in my posting, comment 57#, to say that the Arctic warming would double. It’s obviously only the albedo warming that doubles. But because that warming is now dominant, see comment 75#, the Arctic warming will certainly accelerate.]
[Response: I still don't see why you think that the warming will accelerate much faster than the models suggest since they include these mechanisms. - gavin]
Since the warming of the Arctic is already considered to be causing an increase in weather extremes in the Northern Hemisphere, further warming is bad news by itself.
[Response: This is still an area of 'active research' as they say. It is not clear to me that published attempts to assess changes in variability in recent years have a solid statistical foundation. Maybe, maybe not. - gavin]
And the loss of the sea ice will mean the loss of an entire ecosystem, with repercussions that could include a major food chain, because of organisms that live on the underside of the sea ice.
But we also have to consider what’s happening with the methane. You, Hank, seem to recommend that we ignore the methane, because other issues will become prominent before it “burps”. However, what you don’t seem to appreciate is the risk of methane feedback, where the warming effect of the methane leads to further methane emissions in a vicious feedback loop. Once this gets going, it will almost certainly be unstoppable, as people like Steven Chu acknowledge.
[Response: You discuss thinks with 'almost certainty' that are almost certainly highly uncertain. - gavin]
There are signs of an escalation of emissions from the East Siberian Arctic Shelf (ESAS). Igor Semiletov, a top Russian expert on ESAS and its methane, who I met at the AGU last December, told me that he considers that the ESAS is a prime candidate for abrupt climate change. To my knowledge, nobody has been able to contradict his assertion that there is up to 50 Gigatonnes of methane available for release “at any moment”, e.g. as the result of an earthquake.
[Response: Earthquakes can happen any time and so any release associated with that has nothing to do with climate change, and no amount of emissions reductions will have any effect. However, if you postulate a strong earthquake driven methane pulse mechanism, where is there any evidence that this has been important in the Holocene? - gavin]
However, Nathan has further elaborated on the serious repercussions of a much smaller burp, a mere 3 Gigatonnes; see #125.
Thus, even without further Arctic warming, we have an extremely dangerous situation with the methane. But the retreat of the sea ice and the methane emissions are mutually reinforcing. AMEG claims that dealing with this emergency situation has to involve measures including some kind of geoengineering to actually cool the Arctic, or cool the currents and rivers flowing into the Arctic.
If anybody can show that AMEG conclusions are incorrect, I would be extremely pleased to see their argument.
[Response: It is rather that there is nothing convincing about them. You keep ignoring the fact that there is no evidence for methane burps associated with conditions in the relatively recent past (early Holocene, Eemian) for which there is good evidence for warmer Arctic conditions than now, and you are happy to extrapolate emissions of a few Tg (at most) to values 1000 times larger on the basis of nothing very much. You are going to have to do a lot better than that. - gavin]
would a 3Gt methane burp be visible in fossil record ?
[Response: It would be visible in the ice cores. Pre-industrial emissions were around 300 Tg/year (0.3 Gt), so 3Gt is a factor of 10 greater than all global emissions (and obviously a much bigger factor greater than just Arctic emissions). But at minimum that would more than double the CH4 concentrations for a decade or so. Even with diffusion in the ice core, one would see a spike associated with this in the Holocene or Eemian records. Note too that this would only be a small increase in radiative forcing - less than the sustained anthropogenic increase in methane we have already seen. - gavin]
Nathan and John Nissen,
OK, if these scenarios are credible, then why have they not happened before? Or if you contend that they have, where is the paleo-evidence? Or if we are to dispense with the need for evidence before we consider a scenario credible, can I at least get an “Oogah-Boogah!?”
How well did those models predict the recent expansion of Bering Sea Ice that is currently 160%+ above average. There was a USGS 2010 paper by D Douglas that predicted “For the Bering Sea, median March ice extent is projected to be about 25 percent less than the 1979–1988 average by mid-century and 60 percent less by the end of the century” But if Bering ice is driven by the PDO I suspect that prediction will fail.
This makes me curious about how sea ice loss is modeled. I am under the impression that it is driven by CO2 mediated ice-loss that generates albedo changes resulting in positive feedbacks that increase further melting. How are changes in the the NAO and PDO modeled that can speed/slow the intrusion of warmer waters into the Arctic. I would assume those oscillations are not readily modeled, but the literature suggests several modelers believe the positive phases are controlled by CO2 and become more persistently positive with increasing CO2 .However most oscillations appear to now be headed to negative phases. I would appreciate any insight into how such ocean circulation changes are incorporated into predictions.
Responding to John Nissen in #95 Gavin says “Earthquakes can happen any time and so any release associated with that has nothing to do with climate change,”
I understand there is some debate about whether earthquakes could be related to climate change. Is it not the case that at the end of the last ice age, there was increased seismic activity due to changes in the weight of ice on the earth’s surface?
Currently a few hundred trillion tonnes of land based ice are being removed from the polls each year. Added to this the seas in these regions recede as the gravitational pull of the ice is no longer present, leading to the redistribution of this water to the equator.
Might we see increased frequency of earthquakes as the earth is squeezed round the equator and released at the polls?
Sorry for being a bit late, but for starters I would like to thank Alex/Ron/Cecilia for this post on PIOMAS, and I have a question :
I understand that PIOMAS is forced by NCEP/NCAR data, which I think makes a lot of sense, since that the data that is as close to ‘reality’ as we can get without actually measuring ice volume.
But how about “under-ice” heat flux ? How is that modeled in PIOMAS ?
As I understand it, even a small amount (a few Watt/m^2) of sustained heat-flux very significantly impacts growth of multi-year ice in winter, and possibly make a difference between 6-7 meter MYI and just 1-2 meter ice.
In PIOMAS, is there any change in ocean heat flux over the modeled period (1979 onward) ?
> many other nasty things will have happened
judging from the paleo record as well as the models
> before a methane burp becomes an issue.
“Assessing key vulnerabilities and the risk from climate change
For some impacts, qualitative rankings of magnitude are more appropriate than quantitative ones. … risk is defined as consequence (impact) multiplied by its likelihood (probability), the higher the probability of occurrence of an impact the higher its risk …”
So the issue is — what’s the likelihood of a methane burp before the other expected stages of warming? This is whatchacallit, a decision tree — and the methane burp is the goblin sitting out near the end of one of the branches.
But which branch — at what point in time/temperature would we be turning onto that branch?
We’d need what,
– 4 degrees C overall to see the Arctic ocean warm?
– decades for warmth to propagate to the depths
– a new kind of rapid event not discovered in the paleo work?
I’m just a reader. I can’t claim a methane burp would be any less horrific than described by the worst case claims, just that I haven’t seen anyone documenting it’s happened in the paleo record.
What I read indicates it’s _quite_likely_ the world would already be in hellish condition from known outcomes of known fossil fuel uses we now engage in, before any likelihood of a methane burp.
So — how fast is the vertical mixing at locations across the Arctic? That seems the key missing chunk of information. Who has that info, or raw data that could be mined for the info? Or do we need to wait for a generation of uncrewed probes that can function under the winter ice and report back to get that data?
i see from the dome C data that the largest methane excursion in the last 800Kyr was around 300 ppb. This would correspond to around 1Gt CH4 release or about 0.2% of Shakova estimate of 500Gt fossil carbon store around ESAS ?
Responding to Gavin Schmidt, John Nissen, and several others too. First, here is David Archer’s answer to John Nissen’s question about a “methane burp”, in stark contrast to what Gavin wrote:“A single catastrophic release of methane might not even be visible in the ice core records.”
Elsewhere in the same paper, Archer describes how this could come from the methane trapped in the ice being smoothed through “diffusion within the fern or heterogeneous bubble closure depth,” or simply through the methane sampling not being dense enough, where the maxima of release could be overlooked [Archer, Methane hydrate stability and anthropogenic climate change, Biogeosciences, 2007]. The reference was to a 10Gt release in that case, so it would stand to reason that a 3Gt release could more easily slip by detection.
In terms of the comments about the Holocene record, etc, and Gavin’s saying that there is “no evidence” of such methane burps then: first, let us all also acknowledge that some of the world’s major paleoclimate and methane experts HAVE seen evidence of exactly that [i.e., Nisbet, Have sudden large releases of methane from geological reservoirs occurred since the Last Glacial Maximum, and could such releases occur again? Phil. Trans of Royal Society, 2002]. In fact, I was just looking at a new paper with more such evidence a week or so back. In discussing the Eemian, let me also add this: certainly CO2 levels are the most precise and unequivocal of the climate signals we have from the past, and it is clear that they were nothing like the current day during the Eemian, never surpassing ~280ppm, and rather like our pre-industrial levels. Further, sea levels, of great significance to the state of various submarine carbon stores, were of course also very different, too, and while we normally think of higher sea levels as always making hydrates more stable (explaining the lack of release then), there could potentially be an opposing effect as well, discussed by Archer, in fact (Archer, 2007). One could see these differences of sea level going either way – either the shallow hydrates were kept more stable than they are now, or perhaps they actually did get released more than we have yet ascertained. But in general, it would seem that, since Gavin is discussing John Nissen’s presenting things that are really highly uncertain as being certain, I would simply state that expecting the Holocene record (or the whole Pleistocene record for that matter) to predict what we should expect of sensitive and complex arctic systems in our Anthropocene, at 400ppm CO2 and an arctic where methane is often spiking over ~1900ppb now (versus a little over ~700ppb, I believe, for the Eemian) might itself be guilty of the same problem, because one has mistakenly assumed the certainty of a past analogue when really there isn’t any.
Now, in the discussion of earthquakes, I think John Nissen was simply mentioning mechanisms for abrupt methane release, and thus wrote “e.g. as from an earthquake,” and Gavin pointed out that this would have little to do with warming. John might have been better served by having pointed to landslides or slope failure, and this not only could have been related to warming, but highly relevant to the specific situation at hand that he was discussing. I quote again from David Archer:
Another mechanism for releasing methane from the sediment column is by submarine landslides. These are a normal, integral part of the ocean sedimentary system (Hampton et al., 1996; Nisbet and Piper, 1998). Submarine landslides are especially prevalent in river deltas, because of the high rate of sediment delivery, and the presence of submarine canyons.
Of course, the Lena river delta, with its rapidly warming waters, is central to the ESAS methane situation, and slope failure might be a potential mechanism for sudden releases there.
Further, I think that Gavin’s point about the earthquakes having “nothing to do with climate change”, true in terms of causation, otherwise leaves out something utterly central to this discussion. In the ESAS, as I mentioned above, there are many taliks now, and they are centered around fault zones, where there is geothermal heating on top of the warming of the bottom waters. Where you then have a talik, from this combination of geological and radiative forces, and then there is plenty of free gas underneath that can migrate out easily through pathways once there are such tears, and then you add on top of all that that it is a seismically active zone, one can easily see how global warming could greatly amplify the effects of an earthquake at that fault zone. So the two don’t exactly have nothing to do with each other, although the source of the earthquake, is, as Gavin said, unrelated to the warming.
Now, Archer has written that, “it appears that most of the hydrate reservoir will be insulated from anthropogenic climate change. The exceptions are hydrate in permafrost soils, especially those coastal areas, and in shallow ocean sediments where methane gas is focused by subsurface migration.”
Of course, it is precisely one of those exceptions that is most concerning to some of us, and Archer himself noted that, “The Siberian margin is one example of a place where methane hydrate is melting today, presumably at an accelerated rate in response to anthropogenic warming. This is a special case,” and elsewhere he mentioned how “The most vulnerable hydrate deposits in the ocean appear to be the structural type, in which methane gas flows in the subsurface, along faults or channels, perhaps to accumulate to high concentrations in domes or underneath impermeable sedimentary layers,” which is exactly the situation there, and, since the amounts stored there are so large, even just the non-hydrate cap deterioration could be of consequence by itself, but further that deterioration then allows exactly the flow along faults as discussed by Archer.
Of course, it might be worth noting that Archer’s methane piece, his “Much Ado,” never did try to say that methane burps weren’t quite possible, but rather that they wouldn’t be particularly significant. He justified this attitude through using a time horizon of 100,000 years. This seems highly unwise, and, as I discussed in a piece on HuffPost about it, “Methane in the Twilight Zone, Episode 2,”* the more that you’re planning on doing anything about climate change – i.e., lowering GHG emissions, pulling carbon out of the system through biochar, afforestation, etc – the less sense it makes.
ps – Archer wrote (Archer, 2007): “If 5 Gton C CH4 reached the atmosphere all at once, it would raise the atmospheric concentration by about 2.5 ppm of methane, relative to a present-day concentration of about 1.7 ppm, trapping about 0.2 W/m2.” Is that just a proofreading error? How could it be .2W/m2? Does that make sense?
…nobody has been able to contradict his assertion that there is up to 50 Gigatonnes of methane available for release “at any moment”
I beg to differ. I’ve done several blog posts on Arctic methane after reading a substantial sample of the available science. My criticisms of the Semiletov & Shakhova 50Gt are available here. Search that page for the string “presentation is talking about” and you’ll find the relevant paragraphs. You can find the rest of my posts on methane by clicking on the label at the bottom of that post.
There being some doubt about the magnitude of the 50Gt isn’t the main issue however, even a rapid degassing of a third of that would be serious. For the me the main issues are:
1) Lack of such degassing events in the recent paleo-records, as Dr Schmidt points out this would appear in ice cores, yet the warmth of the early Holocene and the earlier Eemian and Holsteinian interglacials did not trigger a degassing. That’s despite those periods probably being warmer than at present, and crucially in terms of ocean temperature and sediment warming, warmer for much longer periods than the anthropogenic warming (so far).
2) Lack of a credible process by which ocean warming can rapidly affect the bulk of the ESAS methane deposits in the sedimentary column.
3) Lack of evidence that the changes being seen are not long-standing, being largely due to the inundation of the ESAS after the end of the last glacial rather than due to recent anthropogenic warming.
I am certainly not saying there is not a problem, but I see the threat of the ESAS methane as more chronic than catastrophic, and see the risks attendant with the thawing of land permafrost, especially in view of the rapidity of warming in the Arctic, as the more strongly evidenced risk. But again this is likely to be chronic, not catastrophic.
I have to agree with Hank’s ‘tree analogy’, there are bigger issue to face in the short term. The risks of Arctic methane are a footnote, but not a negligible one.
As an aside, you mention that “Since the warming of the Arctic is already considered to be causing an increase in weather extremes in the Northern Hemisphere…”
Francis & Vavrus have recently published interesting findings with regards the behaviour of the jetstream. They note that this “may lead to an increased probability of extreme weather events”, note the use of ‘may’, this is early in a new line of research. Judah Cohen has done a succession of papers linking snowfall advance in Siberia to cold winters in Europe, this is more strongly supported, and seems in turn to be linked to reduced sea ice. Finally the recent ‘cold outbreak’ of late January in Europe seems to me to be the mechanism of Petoukhov & Semenov, see here. Taken together (and there’s more research I’ve not mentioned here), I’d agree with Dr Schmidt’s view that the chages may not yet be statistically strong. But from my reading it is clear that the loss of Arctic sea-ice is affecting NH circulation, and this suggests it will intensify as time goes on. With time it will become statistically significant.
Re #134 – Ah yes living in the UK and sometimes watching Horizon (our BBC sceincy documentary program) I can see that some of this material in the popular media is now quoting scientists (peter Wadhams – do a google search for his name and Arctic) who appear to have saisd something that the media likes (always the hype of doom gets a page or two of news)or using the Global Weirding program that Horizon showed in March to demonstrate that its all true and the climate is changing.
Peter Sinclair is certainly showing some footage from this program. Personally I did watch the Horizon and it concentrated on Texas (well you would as its a place of extremes although flooding and drought are not uncommon) and on Hurricanes (odd one that really as the just is out on that one but they are big storms right) and then on the Sun (denial peice) and then on the Arctic being the culprit for the UK cold winters (wow the UK gets cold winters) and then for mild weather thereafter as the Sun is not the culprit here which although all true is not yet attributed to climate change per se as natural variability is variable and anything can happen on short time scales.
Who knows exactly when ACC will be the culprit in weather events – I know that James Hansen has attributed the Russian and EU heatwares in the zeros to being highly likely ACC enchanced events and maybe they are but the media once it has connected the dots (as it is starting to) then we are in for some more political posturing.
Fun but reality is more nuanced and complex than any of that as this article is pointing out
Most of the information countering this artcile is taken from this graph. FOr most of us lay types its hard to see how the ice will recover from such a 30 year reduction even if its not true and you cant assume it will disappear even if it seems to be.
#130–”How well did those models predict the recent expansion of Bering Sea Ice that is currently 160%+ above average.”
I doubt they did at all–variability on annual timescales is probably basically ‘weather.’ Modeling won’t predict short-term variability–and that’s a limitation, not a failure.
“I am under the impression that it is driven by CO2 mediated ice-loss that generates albedo changes resulting in positive feedbacks that increase further melting.”
GCMs have oceanographic components–see Kate’s Skeptical Science post for a useful and accessible discussion of the architecture of climate models–which surely include currents as part of their ‘dynamical’ modelling. And I know that the fluxes of heat into the Arctic are a major focus of the work of Dr. Maslowski in regional-scale modeling. So I think, Jim, that your impression of the modeling is much too ‘minimal’–but I’ve just shared pretty much everything I know about it. I, too, would be very interested in more detail on this.
#130, “How well did those models predict the recent expansion of Bering Sea Ice that is currently 160%+ above average. There was a USGS 2010 paper by D Douglas that predicted “For the Bering Sea, median March ice extent is projected to be about 25 percent less than the 1979–1988 average by mid-century and 60 percent less by the end of the century” But if Bering ice is d”
The model proposed here is not a concern, Natural Variability as proposed above is the culprit, Alaska was the only cold place in North America, Ice leaves a footprint with just about any weather or sea event.
What about Barents sea? The recipient area of multiple cyclone visits, another footprint: http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/recent365.anom.region.6.html
Sea ice is such a good indicator of weather and geophysical events, I can tell where the center of a high pressure is, especially by looking at newly formed leads, the center of a powerful high punches a hole through the ice!
I know both Wadhams and Ray Bradley, splendid chaps, I think Bradley’s hypothesis resonates much more in the case of methane, because its the speed of the warming change which matters. Gavin quoting the holocene and past times misses that point. This change speed is dizzying us in the Arctic, even snow buntings come back very early this spring, and polar bears are seen on the thin enough sea ice for seals at the North Pole. I look for evidence of methane likewise, I think we don’t have the resolution on networks to catch strange sudden temperature shifts up to 6 degrees in one hour, not due to winds, the temperature goes up 6 degrees then goes back to “normal” cooler. We need to focus more, and we might see why sea ice has evolved, as I show on my blog, so radically in a mere 20 years.
> Dan H.
> Many prefer to use the Torgny Vinje paper
And if you read it, it’s obvious why “many prefer” that one.
Dan H. continues to push natural variation as the answer.
He’s become a good mimic of the way a scientist writes, lacking only facts.
The papers citing Vinje don’t support Dan H.’s claim.
“The current reduction in Arctic ice cover started in the late 19th century, consistent with the rapidly warming climate, and became very pronounced over the last three decades. This ice loss appears to be unmatched over at least the last few thousand years and unexplainable by any of the known natural variabilities.”
#140. Just to clarify: It is important to distinguish between attributing the differences between models (with anthropogenic forcing) and observations to natural variability and attributing the 33+ year decline in sea ice to anthropogenic forcing. While I think there is room for debate for the former, I think the latter is fairly settled.
Comment by Axel Schweiger — 17 Apr 2012 @ 11:11 AM
#140. Just to clarify: It is important to distinguish between attributing the differences between models (with anthropogenic forcing) and observations to natural variability and attributing the 33+ year decline in sea ice to anthropogenic forcing. While I think there is room for debate for the former, I think the latter is fairly settled.
Comment by Axel Schweiger — 17 Apr 2012 @ 11:14 AM
I did think it peculiar that Dan H was recommending such an old paper when there’s far more recent work that covers a longer period and puts recent Arctic sea ice loss firmly into context.
Kinnard et al, 2011, Reconstructed changes in Arctic sea ice over the past 1,450 years. http://www.deas.harvard.edu/climate/seminars/pdfs/Kinnardetal2011.pdf
Dan H, if you really are trying to push the natural change meme – you’re very badly out of date. That was a reasonable suspicion as late as the 1990s, but since the events of the 2000s nobody serious buys it.
If the authors are still around, I’d be grateful if they could clarify their thinking in regard to the published PIOMAS projections in Zhang et al 2010. I’m afraid I didn’t find their methodology very convincing – I know this is an extraordinarily arrogant statement coming from a molecular biologist, but there you go.
Their method runs the model forwards. Each year they pick a random historical year’s “weather”, apply that to the current state of the ice and see how it turns out. Then, for the next year, pick another random historical year’s weather, run the model forwards another year, and so on. They use two different historical pools for the resampling: either the complete 1948-2009 dataset or a more limited 1989-2009 dataset. On top of that, they apply a warming trend of either 2 degrees or 4 degrees from 2009-2050.
The problem is that in doing this, each year in their subsequent forward projection effectively “resets” the surface temperature to whatever the value was during the year the magic 8-ball picked during in the resampling process that created the forcing pool, plus the amount added on to represent the 2/4 degree trend.
Physically, what that does is assume that all warming occurring during the resampled period is random, and there is no AGW trend in this time period. That is known to be an invalid assumption for both periods – in each there is a significant positive trend. For periods where there is a significant trend you can’t simply use an ensemble over this period to estimate random variation since part of the change over that period is due to the (genuine) trend rather than to random variation. Surely the data should first be detrended, then permuted, then the SAT adjusted according to the forecast model. That is, they should be estimating the CV relative to the trend.
Scenarios A1 and B1 (i.e. forcings permuted randomly from the entire 1948–2009 record) are especially grossly affected. Just look the second panel of figure 1 – these scenarios both effectively assume an immediate, unrealistic and unphysical drop of >2 degrees in Arctic SAT! Even with the added 2/4 degrees warming, the projected trend in Arctic SAT doesn’t get back up to 2009 levels until 2035 for the A1 run, and never gets back up to 2009 levels in the B1 run. Put another way, both these runs assume that in the next 4 decades there will only be 4 years hotter than 2009. In the real world, 2010 and 2011 were both hotter.
Both these scenarios are frankly unworthy of analysis. All they tell us is that if there is no further warming for 40 years, and Arctic temperatures remain largely at or below today’s values for another four whole decades, then we won’t lose the Arctic summer ice. No shit, Sherlock. Frankly, it’s profoundly concerning that the model projects any loss in these two scenarios: and we do. Even with these wildly optimistic assumptions, September ice area drops by around 50% by 2050 in run A2, and barely holds its current levels in run B2 despite a sustained drop in Arctic SAT. That’s chilling (pun intended).
Scenarios A2 and B2 have the same problem, but to a lesser extent since the pool is drawn from the generally warmer 1989-2009 period. Of these two, A2 assumes that Arctic warming will continue at around the same rate as previously. That is, they added in an a trend of 4 degrees / 41 years = 0.0975 deg/year, comparable to the 0.093 deg/year seen in the hindcast. The fact that the actual trend seen in the A2 run was 0.084 deg/year simply reflects the stochastic nature of the resampling process. In contrast, the B2 assumes that the rate of future Arctic warming will be half this. Although this range is based on IPCC GCMs, given the historical record B2 seems hard to justify. This thus leaves A2 as the only realistic projection in my view.
Nevertheless, the conclusions from the A2 run are apparently encouraging in that September ice extent stays above ~5 million through 2020, and above ~2 million through to 2050 (eyeballed from Figure 1, so will not be precise!). This is a robust finding and is replicated in two further runs A2′ and A2″, which I assume they ran in the knowledge that A2 is the only realistic scenario.
However, look at the volume figures. As they themselves acknowledge, these plummet.
“The September ice volumes of A2 and B2 drop to very low
levels as early as around 2025 and remain almost flat in
the following years when the projected September ice
extents continue to fluctuate significantly annually (Figures 1d
and 1e). This suggests that summer ice volume is more sensitive
to AW than summer ice extent”
At face value their numbers suggest the Arctic will be left with an extensive cover (>4 million km^2) of ice but only a small volume (< 2 million km^3): i.e. on average the ice will be less than half a metre thick.
They interpret this as showing that ice area is robust to AGW for the next few decades. I think this rather shows the model doesn't adequately represent ice breakup processes. Ice under a given thickness just fragments, gets mixed with surface waters and melts out. PIOMAS is known to overstate the thickness of thin ice anyway (Schweiger et al 2011).
The upshot is that if the Arctic ice follows their only realistic forcing scenario, by 2025 it's not going to be recognisable – it'll be an eggshell-thin layer that poses no barrier to shipping. I don't find this particularly encouraging.
The study indeed assumes that the all of the variability in the base periods is natural. Therefore the climate noise in the projections is exaggerated. The evolution of the trajectory comes from the superimposed temperature trend and the model sensitivity. As you can tell, the model quickly forgets the initial conditions once the artificial atmosphere is introduced. So the noticeable break in the surface temperature changes doesn’t last very long. Since the projected surface forcing changes come from a climate model(s) the underlying assumption is that the important ice-ocean feedbacks are captured in the superimposed forcing changes, so it really isn’t an independent test and not meant to be a substitute for a coupled model. This experiment simply shows that having a more realistic spatial distribution of sea ice doesn’t alter the results very much.
As you can tell, the model quickly forgets the initial conditions once the artificial atmosphere is introduced
Yes, but that also involves “forgetting” half the total warming from 1948 through to the present! That is, it “forgets” the initial 2009 temperature and drops down to the temperatures you’re feeding it (plus the additional exogenously-added trend). So yes, if you “forget” that the Arctic has already warmed several degrees, the ice tends to remain.
the noticeable break in the surface temperature changes doesn’t last very long.
I disagree vehemently. In the B2 run, the SAT trend in the projection NEVER gets back up to the 2009 value, and only 4 individual years in the entire run are above the 2009 value.
Two quick points
Since ice response at the end of summer is the integral of meteorological forcing, getting the timing of individual weather events correct is not required.
Using a range of summer climatological weather distributions is not too poor an approach for a probability outlook.
Current climate models (CMIP3 & 5) seem to be slow for a variety of reasons. comparison with data, model resolution and lack of regional physics. It is not clear that they will solve the problem any time soon
Comment by James Overland — 18 Apr 2012 @ 10:06 AM
129 Ray L asks, “if these scenarios are credible, then why have they not happened before?”
For the Holocene, the warmth of today is NOT separate from the warmth 8kya. Instead, it is laid on top of. Put a fire under some water, and it doesn’t boil… does that indicate that placing a fire under water for a longer period won’t cause the water to boil?
The previous ice ages are another matter, of course. Then again, they’re not nearly as constrained. Also, natural interglacials are slower than the current events and clathrate atmospheric CH4 emissions are limited by the capacity of ocean organisms to consume CH4, so exceeding that limit is more of a potential problem today. A big natural release over 1,000 years might result in ~0 atmospheric CH4 increase. Do the same today in 50 years, and CH4 could increase tremendously.
The big question in my mind is whether the potential release is self-limiting. The gulf oil spill involved clathrates. They tried to cap the leak, but expansion caused freezing and clathrates gummed up the works. Will that happen naturally so leaks will self-seal?
Now this is the worst captcha I’ve ever seen. The first half HAS NO LETTERS! Just a picture. Just how am I supposed to represent that??? Please please PLEASE dump your current provider and get a system that allows humans to post relatively easily.
Clearly, the sea ice volume data plot is the single most important topic of discussion, yet in the article it is shown in Figure 1 with a poor vertical scale and amongst linear trend lines which mislead and make the curve appear to be linear and reach the zero point far out in the future. The data does appear also in Figure 3 and with an exponential fit although in this figure the data is somewhat concealed amongst a plethora of other curves.
It is important that the readers see the data clearly displayed, for this I would refer them slide 24 of the presentation: http://www.cmos.ca/Ottawa/SpeakersSlides/PaulBeckwith_19Jan2012.pdf ,one can clearly see that a linear trend line to the data makes no sense. In fact I asked my 9 year old where the curve is trending to zero, and he correctly responded 2015, as most people would conclude.
It is important to note that the PIOMAS volume curve is for Pan-Arctic ice, the prefix indicating that it includes ice outside the Bering Strait into the Pacific. It is clear that this ice will melt every year, so the actual volume withing the Arctic proper is even less than the data indicates.
The ambiguity over the definition of ice-free is not really important as far as the strong albedo feedbacks magnifying the warming of the region, so is kind of a red herring in the discussion.
How can anybody have much confidence in the so called “published projections” for the ice free state between 2037 and 2100, given that these projections have been wrong every single time they have been made over the last decade or more; they missed the collapse in area in 2007 and they also missed the exponentially declining behavior over the last several decades.
Invoking the natural variability explanation for making a prediction based on so called “simple extrapolations” is also a very dubious claim. Simple physics dictates that with less sea ice there is magnified warming of the Arctic due to powerful albedo feedback; this in turn reduces the equator to pole temperature gradient which slows the jet stream winds causing them to become more meridional; this combined with 4% more water vapor in the atmosphere (compared to 3 decades ago) is leading to much more extremes in weather. There is nothing “natural” about these extremes of weather over the last 2 years, or about the unprecedented ozone hole in the Arctic last year (troposphere warming from greenhouse gases caused stratospheric cooling to below threshold temperature for polar stratospheric cloud generation and ozone destruction). Neither is there anything natural about the large variation in the Arctic Oscillation (AO) from record positive to record negative levels). Ditto with the rapid increase in methane emissions from the Arctic region as flask measurements indicate, as well as satellite measurements. Both methane datasets show a very large increase in methane in 2011 versus 2010, this is also confirmed by Russian measurements on the East Siberian Arctic Shelf (ESAS) which saw methane plumes of 1 km in diameter when a year or two previously the plumes were a mere tens of meters in diameter.
If you just consider the Arctic alone, then maybe you could argue on some anomalous years of low sea ice. However, when you look at all the “big picture” evidence of the global system it is clear that there is nothing “natural” about it, in fact it appears that the planet is in early stages of an abrupt change of climate from our “normal” system to one that is much warmer and tropical like. Over the ESAS the temperatures were 20 degrees Celcius higher than normal for much of Jan/Feb/Mar this year, and of course the March heat wave broke enormous numbers of records, not to mention the massive numbers of tornadoes spinning off the supercharged storm systems. Nothing normal about all this. Time to step away from the models and pay more attention to the observations…(more details in pdf link http://www.cmos.ca/Ottawa/SpeakersSlides/PaulBeckwith_19Jan2012.pdf )
Click the little icon with the two circling arrows for a fresh choice.
(Pictures are “Street View” addresses, generally, these days; it changes)
This is a fast changing “arms race” — well funded spambot herders (Motto: “We will bury you! In Spam!”) versus websites. None of the responses are easy; I’m seeing more sites give two or three different challenges per post.
I’m also seeing small websites simply choked to where the owners give up.
Excellent posting. All your points support AMEG’s assertion that we have a planetary emergency on our hands.
But what do we do about it? Clearly the Earth System will not return to any kind of normality (hospitable for humans) without intervention. If we let the sea ice disappear completely and the methane rip, then we are sunk. So we have to take some measures to cool the Arctic.
And we have to do it on a large scale, so it involves geoengineering – preferably using a number of techniques in combination. But we can take immediate measures to avoid the risk of inadvertent warming, e.g. from gas or oil spills. And we could even allow more sulphate aerosol into the atmosphere, as this has proven successful at global dimming – taking care about not to release “pollution” near centres of population where it could damage health. I’m sure there are other things to do if we put our minds to it. Necessity is the mother of invention.
The evidence suggests we could already be at the point of no return. So we have to fight to save the situation with utmost determination. There is no time to lose.
Concerning predictive functions: With something wobbling so much up and down as the volume curve, just putting your finger on the screen and drawing a freehand curve is not less precise than any fit function, much more economical though.
Axel Schweiger wrote, that we had just a couple of warm springs, which caused the deviation from the GCM predictions, and this is one interesting point: Is this “couple o’ warm springs” really something coming and going like any cyclone, or is it a sign of a changing weather regime with stronger mixing and stronger heat transport? There are arguments for the latter, e.g. change in jet stream trajectory (http://nsidc.org/arcticseaicenews/category/analysis/). For the time being we cannot be sure, but this might be an effect escaping the GCMs so far.
Paul Beckwith, I would also beware of invoking “simple physics” in making predictions about a complex system. Gavin has already pointed out that ceteris probably ain’t paribus, as there could be negative feedbacks due to clouds that diminish the positive albedo feedbacks.
I agree completely that with the fluctuation in the volume curve one can eyeball the curve and do a decent fit, in fact my 9 year old son said it looked like the zero crossing was at 2015. Not necessary to get a room full of Ph.D.s to see what the trend is in this case.
I disagree completely with the Axel Schweiger “couple of warm springs” explanation to describe the last few years. In fact in my presentation( http://www.cmos.ca/Ottawa/SpeakersSlides/PaulBeckwith_19Jan2012.pdf )on slides 26 through 45 I discuss how the extreme weather is a pattern and not an anomaly, and how meteorologist Jeff Master is going ballistic about the last two years, as is ClimateProgress blogger Joseph Romm (quotes on slide 45). I am sure this is a pattern and not a simple excursion from the norm, as is James Hansen. Particularly damning is Hansen’s climate dice analysis showing the spatial distribution of heat events around the globe in standard deviation units (slide 42); the enormous increase in heat events exceeding 2 sigma and 3 sigma within the last decade show an undeniable pattern of increasing extremes.
Clearly, these extremes are global and nature and there is every reason to conclude that they will increase in frequency and intensity as the sea-ice collapses further. The main question is when will these extremes hit the global food supply and cause shortages, just this week there are articles about how China’s rice and grain crops are being stressed by flooding and drought events. Remember that when the jets stayed in a stationary meridional blocking pattern for about 5 weeks or so over Asia a few summers back Pakistan was flooded out (being in the trough) and Russia was baked and burned (in the ridge), the grain crops were hammered there so much that there were no exports from them that year. The same meridional blocking pattern hit North America this March, keeping the East at record high temperatures and the West colder than normal such that it snowed in Northern California and also rained much more than normal. What more do we need to be sure?
[Response: The problem with all of this handwaving is that you are equating coincidences in time (-ish) with causation. Where is the mechanistic analysis that says that it is the sea ice over the last couple of years (and not SST, or north-south gradients, or strat-trop connections or whatever) that has caused this? Where is the statistical analysis that says that you can confidently say that blocking variability has become greater in the last couple of years? The fact is that you are making claims of certainty where no such certainty exists. It is not inconceivable that sea ice extent changes affect jet stream volatility - but this needs to be quantified. By how much does it affect the variance? and is it conceivable that it is so large that it is confidently detectable in only a few seasons? Do some of the maths - and you'll very likely find that only ridiculously large shifts would be confidently detectable in such a short time, and there is no evidence for such large changes. Note that your use of Hansen's graph to support your claim doesn't follow since his result arises from a shift in the mean even in the absence of any shift in the variance. I totally get that you are concerned, and that these connections may be happening, but you are not doing yourself any favours in trying to convince anyone else of that. Take a step back and start thinking about detectability and quantify what you are interested in - that, in the end, will be much more telling. - gavin]
I do not buy the blanket statement that the climate system is all complex. There are “core” linkages that the physics clearly explains with absolute certainty and of course there are many “peripheral” connections where things get more complex and obscure. For example simple spectroscopy dictates that the CO2 molecule vibrates, stretches, and rotates creating quantized absorption lines that are Doppler broadened and pressure broadened and absorb the infrared radiation coming from the warmed planet. Snow and ice has a high albedo and when it is replaced by sea water or soil and tundra the albedo drops and there is warming, this is simple optics. Slide 8 of http://www.cmos.ca/Ottawa/SpeakersSlides/PaulBeckwith_19Jan2012.pdf shows the spatial warming, the Arctic amplification of the warming is enormous and is due to this “core” albedo effect. Sure, there are some negative effects from clouds but they are clearly not preventing this large latitudinal amplification effect.
I should qualify that I have a multidisciplinary background with an undergraduate degree in Engineering Physics and an M.Sc. in laser physics, an I am working towards a Ph.D. in abrupt climate change in a Geography department, however this has not stopped me from sitting in on many human geography and policy courses. I completed all the courses required towards a Ph. D. in physics, and I have audited many courses in Earth Sciences and mathematical physics.
A huge problem is that far too many scientists (including climatologists) are way too specialized in niche areas of their field and refuse/hesitate to step outside their comfort zones to study the “big picture”, which is vital step to enlightenment in the field…
#155–I’m sympathetic on several counts. But the March heat wave was not a global phenomenon; NCDC has March as the 16th warmest ever, and the coolest since 1999. (Still warm in the big picture, but far from remarkably so by 21st century standards.) Citing it in this context just weakens your case.
Detectability may require new tools though. While the mean shift argument works well for NH summer, in the spring we often speak of a phase shift such as an early spring or summer come early rather than a mean shift. The shift in the mean for spring is about the same as for summer but the variiance is much larger in the spring so the attribution argument that works in the summer does not work in the spring. I suppose shifting hardiness zones is one quantification but something that captures just how wild March was seems a little hard to find.
Paul Beckwith, The statements you are voicing are not based on evidence. They are opinions. They may be correct. There’s even a reasonable probability that they are so. Nonetheless, they do not change the fact that there is a whole helluva lot we don’t understand about what is going on in the Arctic at present. Very little is clear, and none of it is simple. That is not something from which to draw comfort.
It’s not a published source from a scientific journal, but it is an interview with a major climate scientist, Kevin Trenberth.
“For every one degree Fahrenheit increase in sea temperature, the water holding capacity for the atmosphere goes up by 4%. And since the 1970′s on average there’s about a 4% increase in water vapor over the Atlantic Ocean and when that gets caught into a storm, it invigorates the storm so the storm itself changes, and that can easily double the influence of that water vapor and so you can get up to an 8% increase, straight from the amount of water vapor that’s sort of hanging around in the atmosphere. This is reasonably well established.”
I have followed ice news closely over the last 3 years and I am worried about future ice loss. But can anyone explain how we have had previous ice free occurrences in the last 100 years or so. If I understand correctly then 1934 or 1953 were “ice free” or very low at least. The problem is that if this is true then public opinion is less likely to be too concerned with it happening again.
Also, it appears by looking at the antarctic ice graphs that the antarctic is doing well and has if anything slightly increased over the last 30 years or so. Wouldn’t we expect this to be behave in similar way to the arctic?
[Response: What is your source for 1934+1953 being 'ice free'? sounds remarkably implausible if you ask me. As for Antarctica - there are many differences, not least the heat content of the Southern Oceans, the isolation of the continent, mostly divergent sea ice flow, etc. And penguins. - gavin]
Andrew Holder, are you the same Andrew Holder who has had some comments at Wattsupwiththat? If so, it explains your confusion. When you go there, you are fed so often with misinformation, it is difficult to enter back into reality.
Andrew, this claim is flat out false. I’ve seen the 1934 claim before, but never supported by anything other than fragmentary anecdotes–and actually, IIRC, “anecdotes” is a generous description; “a single vague reference” would be more like it.
Quick Google searches:
1) Japanese observations in the Sea of Okhotsk from 1934 (note that this area is relatively southerly, so if there’s ice there, we can be quite sure there is lots of ice elsewhere):
#172–”Wouldn’t we expect [antarctic sea ice] to be behave in similar way to the arctic?”
Well, given that:
1) the Antarctic ice is largely seasonal, whereas the Arctic ice has historically been semi-permanent (formerly having a considerable amount of ice more than 10 years old); that
2) the Antarctic ice forms at the margins of a largely glaciated continent surrounded by a powerful circular ocean current, whereas the Arctic ice forms at the margins of a ocean basin largely surrounded by continental landmasses; and that
3) the Antarctic (with the notable exception of the West Antarctic peninsula) shows low rates of warming, whereas the high Arctic is the most rapidly warming part of the planet–
no, this observer, at least, really wouldn’t expect them to behave in a similar way at present.
Yes I am, i know it’s strange to some people but I like to read and digest information from all sources and then make up my own mind about things.I think it’s a sensible question to ask why antarctic ice is increasing when arctic ice is decreasing but I understand that might be a topic for another post as it will probably, as Gavin indicated, involve many different areas for discussion. As for previous years when arctic was “ice-free” i think one of these possible sources is from old pictures of submarines or ships being “photographed” at the North Pole, eg in 1958 http://en.mobile.wikipedia.org/wiki/USS_Skate_(SSN-578) although I understand that this has been open to debate. As in all these things, nothing is black and white – even in old photographs!
As other posters have pretty much scuttled the Arctic portion of your concern, I will confine myself to the Antarctic. There are a lot of things that folks seem not to understand about the poles. The first and perhaps most important is that while they are warming, they are still bloody cold–especially in winter–and hence, ice will still freeze. In Antarctica, this means that cold and moister air from the surrounding oceans will blow over the interior and fall as snow, so increasing ice mass is to be expected. It is along the edge of the continent where we are seeing deteriorating ice conditions. Ice shelves are collapsing. That is not healthy.
I am not sure why Gavin replies “[Response: What is your source for 1934+1953 being ‘ice free’? sounds remarkably implausible if you ask me.”
Indeed, there is no way to truly compare ice coverage during the 1930′s to 40′s but the source of that speculation was pictures taken from submarines that surfaced at the north pole with considerable open waters. I don’t think there is enough data to say such conclusions are justified or to dismiss as “remarkably implausible” but the temperatures in the Arctic during that time were remarkably similar to this current period and the subject of several peer reviewed papers. For example:
In “The Early Twentieth-Century Warming in the Arctic—A Possible Mechanism” BENGTSSON 2004 , they wrote “The largest warming occurred in the Arctic (60–90N) (Johannessen et al. 2004) averaged for the 1940s with some 1.78C (2.2C for the winter half of the year) relative to the 1910s. As can be seen from Fig. 1, it was a long-lasting event commencing in the early 1920s and reaching its maximum some 20 years later. The decades after were much colder, although not as cold as in the early years of the last century. It is interesting to note that the ongoing present warming has just reached the peak value of the 1940s, and this has underpinned some views that even the present Arctic warming is dominated by factors other than increasing greenhouse gases (Polyakov and Johnson 2000; Polyakov et al. 2002).
#172 Andrew’s source? Would it be the Larsen taking 2 years to sail through the NW passage, instead of less than a week now a days??? Or is it some secret Nazi Arctic submarine navigation chart smuggled to Argentina after the war, the U-boats needed to surface often for air, and it was so ice free they had a regular sub charter schedule to Japan. By the way the same war in the 40′s during which the 3rd Reichs war machine froze dead on its tracks just short of Moscow??? No no, lets see, must be something more obvious… Please elaborate!
But be warned, there is no such memory of such warm times by the people of the Arctic, sorry that there was no weather stations, but there were people here, currently entranced by a real current warming period.
I suggest Spitzbergen records…
“… A knot of sailors in the control room stared intently at an instrument inscribing patterns of parallel lines on a rolling paper tape. The pattern looked like an upside down mountain range.
“Heavy ice, ten feet,” said one of the sailors.
Suddenly the lines converged into a single narrow bar. “Clear water!” the sailor called out.
Calvert turned toward the man in charge of the ice-detecting instrument. “How does it look?” The sailor flashed him the okay sign.
“Bring her up slowly,” Calvert said. The three-thousand ton sub began drifting upward like a giant balloon. The diving officer called the depth as the Skate rose.
Otherwise the room was deathly quiet. A wrong move or a miscalculation would endanger the mission or even the ship. Calvert continued to peer through the eyepiece. When the top of the periscope came within sixty feet of the surface, he spotted heavy ice to the side. He flipped the prism to look straight up, but saw nothing except the same blurred aquamarine. Sweat appeared on his forehead as he felt all eyes in the control room bear down upon him. If the sub rose too slowly, it could drift away from the opening. If it rose too quickly and struck ice, the collision could tear open the pressure hull and send the sub and all ninety men on board to the bottom.
… The submarine’s black hull stood out in stark relief against the deep blue of the calm lake in which the ship now floated. Beyond the lake, stretching to the horizon in every direction, was the stark white of the permanent polar ice pack. The officer who had climbed to the bridge with Calvert called the skipper’s attention to the port side of the ship. There a full grown polar bear was climbing slowly out of the water and up onto the ice.
The date was 11 August 1958 and the Skate had just become the first submarine to surface at the North Pole.”
Note mentions of the ice when the Skate surfaced– as it says there, very thick and variable; the quote mentions ice at 10 feet and 60 feet below the surface, for example.
Current conditions: “The overhead ice canopy, with ice keels that can reach as deep as 200-feet, adds another layer of operational complexity that submarines do not routinely encounter. Additionally, salinity differences throughout the Arctic Ocean present challenges to even the most experienced sonar operators.” http://www.navy.mil/navydata/cno/n87/usw/usw_summer_09/icex.html
Exactly. Back at the end of the last century it was thought possible that natural variability was a key driver of the current phase of Arctic sea ice loss.
Now, a decade on, nobody serious buys that.
Bengtsson 2004 figure 1 shows that the pre 2000 warming is greater than that of the 1920s – 1930s. A co-author of that paper Ola Johanessen in a paper of which Bengtsson was a co-author “Arctic climate change: observed and modelled temperature and sea-ice variability.” (Tellus 2004) shows that whilst the 1940s warming doesn’t appear in all simulations the recent warming does. Hence whilst the recent warming is a forced response, the 1940s warming was likely mainly internal variability of the climate. They also find that “the warming trend for the last 20 yr is more widespread and has a markedly different pattern from the earlier periods [1920s-30s] in both winter and summer.”
They conclude that “anthropogenic forcing is the dominant cause of the recent pronounced warming in the Arctic.”
Really this game of trying to pretend that the changes in the Arctic are natural, or commonplace in human history is very boring and unproductive.
US submarines are being chartered for commercial operations under the ice.
— petroleum companies? Who else?
A Canadian blogger writes:
“The United States, in particular, denies that the waters separating Canada’s Arctic Islands belong to our country. Because they want to ship through those narrow straits, and would like to drill for the oil and gas …, the US maintains the waters are international and open to anyone.
Increasingly, the US is trying to find work for its multi-billion dollar fleet of strategic submarines. Four Ohio-class ballistic missile boats have been converted over to support special opeerations.
… US Navy submarines routinely carry researchers involved in private projects sponsored by academics and corporations. It is probable that – if they aren’t doing it already – the American Navy will use some of their underultized submarines to explore beneath the Arctic ice for minerals and energy deposits.
That would be the first step in a concerted effort to dispute our claim to the Arctic waters…..”
The same blogger on the same page points out that there’s an inexpensive alternative for operating under the ice now:
“Germany, Sweden and China are all having good success with a new technology, called Air Independent Propulsion (AIP) for diesel-electric submarines. It eliminates the traditional weakness of the time-proven diesel submarine design – which requires the boat to either surface or use a “snorkel” to vent fumes and draw in fresh air when the diesel engine is employed to operate the sub or to charge its batteries.
Diesel electric subs are quieter than their nuclear counterparts, because pumps are required to continually move water through the boat’s nuclear reactor to cool it. A diesel-electric sub simply runs on batteries. Solve the recharging problem, and you have an undetectable submarine for a fraction of the price of a nuclear boat.
It wasn’t an idle gesture. The same year, a Chinese AIP submarine surfaced in the wake of the American aircraft carrier John F. Kennedy in the Sea of Japan. The crew of the Kennedy had no idea it was there until it was spotted by the pilot of a landing F-18 jet.
Had the Chinese sub had hostile intent, the Navy knew, super-carrier would have been lost.
The Swedish sub exercised with the US Navy off San Diego for 24 months (http://militarynuts.com/index.php?showtopic=1453). While the results have never been released, sailors who were involved in the exercises were quoted as saying that the Americans were never able to hear the Gotland, despite operating the most sophisticated sonar systems in the world.
The AIP subs can stay submerged and operating for three to five weeks, while traditional diesel electric like the Victoria-class boats in the Canadian Navy, have to come up to breath every 20 to 24 hours…..”
#177–Jim, are you suggesting (in light of my links which show observers charting ice in the Arctic in 1934 and in 1953) that it’s even remotely plausible that it was ice-free and not one observer mentioned that fact?
Ice retreat, possibly, though to present-day levels is most unlikely.
Ice-free, no way.
As to ‘submarine pictures,’ don’t even bother. Large leads can and do form at any time in the pack ice, and sub commanders consistently use them (if they can find them) in preference to busting through the ice with their conning towers. And as far as I know, all extent ‘sub pictures’ date from late in the 1950s, after the years in question, anyway.
Indeed, there is no way to truly compare ice coverage during the 1930′s to 40′s but the source of that speculation was pictures taken from submarines that surfaced at the north pole with considerable open waters.
What was the name of that submarine that surfaced at the North Pole in 1934?
I’m having trouble remembering … please help me out …
And while you’re at it, the name of the sub that surfaced there in 1953?
Those are the two dates mentioned by Andrew.
I don’t think there is enough data to say such conclusions are justified or to dismiss as “remarkably implausible” but the temperatures in the Arctic during that time were remarkably similar to this current period and the subject of several peer reviewed papers.
Now, moving on to 1958 …
1. The Skate never surfaced at the north pole, despite Watts’ claims to the contrary.
Jim Steele @~177 provides a reference that asserts extreme warming from 1910 to 1940 and
the ongoing present warming has just reached the peak value of the 1940s
I thought this might be misleading so did a little armchair amateur search. On the whole, the conversation about melting has been about the years since 1979 when we have more complete and accurate measurements, but I don’t think one can support the above assertion unless you work hard to exclude any inconvenient data. Although recent acceleration takes a while to be incorporated in the records, even without it this is not correct. The graph I found (ACIA*) appears to be cut off at about 2003 which makes it slightly favor what is IMNHSO a false assertion, but even so it doesn’t look that way if one uses unbiased eyes.
If you look only at single years and hide your eyes from the clumps of data, and ignore the last ten years, you can almost support that assertion. But it takes an effort to ignore the surrounding information.
*An international project of the Arctic Council and the International Arctic Science Committee (IASC), to evaluate and synthesize knowledge on climate variability, climate change, and increased ultraviolet radiation and their consequences. The results of the assessment were released at the ACIA International Scientific Symposium held in Reykjavik, Iceland in November 2004. http://www.acia.uaf.edu/
As the publications cited were from the early oughts, it might also be appropriate to note that the Arctic warming picture has passed from a less noticeable trend supporting the strong theory supporting warming to obvious with a strong signal in the last 8-10 years.
– (these dashes denote change of focus)
Kevin McKinney@~174, thanks for all the heavy lifting on observations, useful for reality-based community in yet another knuckle-dragging skirmish. Every little thing seems to be used to stoke the fires of the hide your eyes contingent, but we can hope a thoughtful reader or two will take note of this information.
About that 4% increase in water vapor, it’s been around for a while (Trenberth) but I’m wondering if there isn’t now a bit more? Hasn’t it grown?
Chris Dudley@~163 voices the question we must all be asking – there must be some better ways to quantify how off the wall things are becoming.
Of course, we all must realize that absent something we don’t all know about (or the methane shock troops being right, which the science does not appear to support; while faintly agreeing that increased methane can’t be good it appears the more knowledgeable sorts are saying the quantities are out of whack for going all shock-horror on it just yet, while other problems multiply and are bad enough without giving ourselves nightmares), the weather is going to return to something more like normal in the next couple of years.
I don’t know how Dr. Hansen nailed it when he said that 2012 was going to be really bad, but it sure is looking that way.
captcha: religious leceduc which I nominate “lord luv a duck”
PS for Jim Steele, there’s a correction in comments at that Navy page. I don’t vouch for the facts either way, but note this too:
“Graham P Davis says: (October 30th, 2011)
USS Skate did indeed surface at the North Pole but not until 17 March 1959. Ice conditions in August 1958 were too heavy at the Pole for the Skate to surface, as they were for the Nautilus some days earlier. The Skate did surface in several other leads and polynya that August, including one near Ice-station Alfa. The above picture may have been from one of those.
When the Skate sailed for the Arctic the following year, the sail had been strengthened to allow it to break through thin ice. At the Pole, they eventually found a small, refrozen lead, or skylight, and managed to break through it. Later, many of the crew gathered for a service at which the ashes of Sir Hubert Wilkins were sprinkled in the wind. The temperature during this service was -26F (-32C).”
“… This data set includes submarine data collected in the Arctic Ocean by U.S. Navy and Royal Navy submarines. U.S. Navy guidance has stated that previously classified, submarine-collected ice draft data may be declassified and released according to set guidelines. Those guidelines include restrictions stating that positions of the data must be rounded to the nearest 5 minutes of latitude and longitude, and date is to be rounded to the nearest third of a month. The guidelines also specify a region in which the data may be released. The Chief of Naval Operations has expanded the release area beyond the original “Gore Box” (so called because of Vice President Gore’s advocacy for releasing the data). See the map …” https://nsidc.org/data/docs/noaa/g01360_upward_looking_sonar/images/subboxes.gif
“… Kwok and Drew Rothrock of the University of Washington, Seattle, recently combined the high spatial coverage from satellites with a longer record from Cold War submarines to piece together a history of ice thickness that spans close to 50 years.
Analysis of the new record shows that since a peak in 1980, sea ice thickness has declined 53 percent. “It’s an astonishing number,” Kwok said. The study, published online August 6 in Geophysical Research Letters, shows that the current thinning of Arctic sea ice has actually been going on for quite some time….” http://www.eurekalert.org/pub_releases/2009-09/nsfc-sas090109.php
“Ice Draft from Upward-Looking Sonar
101 data points, each a 50-km average. Profile data in archive. … basic measurement Hx,t,l comes from the upward-looking sonar and is the ice thickness … Wensnahan (2007), ‘The Accuracy of Sea-Ice Drafts Measured from U. S. Navy …” http://courses.washington.edu/b111/Don_overheads.pdf
And a reminder that the best equipment the world has ever known for navigation under the ice can still be off by a bit, when checked:
“… After the 180-mile sprint was complete, we found a surfaceable feature and punched through. The moment of truth had come. The GPS fix indicated that we were on the exact latitude line the quartermasters had calculated by the hand DR, but the heading error placed us 145 nautical miles due east of that position! That was tough to swallow. In hindsight, I was happy enough just being on the right chart. The Mk-19 Gyro was re-started and provided the heading reference …. Eighteen hours later, we were underway with three separate heading sources working well.
We completed our transit of the North Pole while the embarked scientific team accomplished their own goals, dropping 77 under-ice conductivity-temperature-depth probes along our track for collecting data. With the excitement of the scientific mission behind us, the only obstacle remaining was the Bering Strait passage, which would entail traveling submerged 1,000 miles inside the 100-fathom curve with ice pack overhead….
… Will we ever enjoy the same success we had with the Sturgeon class again, or are we retiring our one true under-ice capability for good?” http://www.navy.mil/navydata/cno/n87/usw/issue_10/arctic.html
Hmm, the point in my overlong sentence was meant to be, that in the normal course of events, 2012 will become another year out of whack with the trend, just like 1998, unless something we don’t know about is under way.
The normal thermostat for identifying the unusual is likely to be adjusted upward. In the midst of all this, the truth remains our only hope. The truth, and a lot of it. It is tempting and even possibly true to say that this is what the beginning of a tipping point might look like, but premature to insist.
The stoking of fear has been a weapon of cultists since the beginning. It doesn’t work to join the forces of darkness. The truth is defenseless but unchangeable; one can hope it will prevail in the face of tawdry exploitation.
I would rather “hand wave” and be correct rather than “mechanistic” or “statistical” and be wrong. Many scientists are like chess pieces on a chessboard, their knowledge and worldview is based on the given square that they occupy and the squares that they can legally move to.
I would rather be the chess master that sees the pattern amongst all the pieces, consider the strategy and tactics that the whole board and the entirety of pieces dictates,and projects where the game is headed and what the other player Earth is liable to do,as opposed to being one of the pieces myself. Calling the player a “hand waver” because they are not a chess piece is just silly…
I do not have time now to post a detailed defense of my previous postings with peer-reviewed support until early next week when I fire my next salvo of torpedoes at the erroneous hope that the sea-ice will be around like the models claim. I hope that everybody enjoys Earth Day, and contemplates a world this decade with no Arctic sea-ice.
[Response: You (and indeed anyone else) is entitled to hold any unsubstantiated view you like. However, if you want to claim that opinion is scientific, there is a higher bar. And if you want to convince other scientists that you are correct, there is an even more work to do. It is not because people are prejudiced against new ideas that this is needed, but rather it is to distinguish strongly held opinions (of which there are many) from scientifically supported theories (of which there are few). If you reject the discipline that this forces on you as being somehow not relevant to your particular point, then you end up sounding like any number of homeopaths, astrologers and assorted cranks. That is not the way to win citations and influence scientists. - gavin]
And, of course, I doubt Jim Steele will be back. These folks are typically drive-byes, and are not interested in learning facts. They’re convinced they’ve learned all there is to know at sites like WUWT. Facts won’t interfere with that, especially if they don’t revist and read them …
I see my reply hasn’t been post, so on the off chance it was my mistake and not another blow to freedom of speech I repost:
Wow, that was a bountiful counter-attack for something that was not the point of my post. I never tried to argue the extent of the ice and indeed only spoke the the “source of the speculation” was the submarine photos. Indeed all your replies simply support what I said, there is not enough data to argue how much ice was present at that time, so I give llittle weight to CO2 advocates or skeptics in this regard. Please try to keep to the points and not create straw dogs to attack using my name. Again I wrote “Indeed, there is no way to truly compare ice coverage during the 1930′s to 40′s but the source of that speculation was pictures taken from submarines that surfaced at the north pole with considerable open waters. I don’t think there is enough data to say such conclusions are justified or to dismiss as “remarkably implausible” but the temperatures in the Arctic during that time were remarkably similar to this current period and the subject of several peer reviewed papers.”
My criticism of Gavin reply was simply that the temperatures at the time suggest it is not ‘highly implausible’, but because of the observed warming that it was certainly within the realm of possibility. Only Chris Reynolds reponsded with
“A co-author of that paper Ola Johanessen in a paper of which Bengtsson was a co-author “Arctic climate change: observed and modelled temperature and sea-ice variability.” (Tellus 2004) shows that whilst the 1940s warming doesn’t appear in all simulations the recent warming does.’
I’d like to suggest to you Chris that you look at Johannessen’s Fig 1 more carefully. When the model was run with natural variability it captured the 30′s polar warming but not the late 20th century warming. After adding CO2 in Fig 1b, it was too warm but after adding some arbitrary amount of sulfates in 1c they reduced the extreme heat and come closer to the 20th century warming. I find it amazing that they then claim that only after adding greenhouses gases can they replicate recent climate. For those who have not stuck their head in the sand, please notice that the natural warming of the 1930′s and 40′s was eliminated. The real scientific conclusion would be that their models failed to capture the recent and the past warming correctly, and when they approximate one they lose the other. Therefore the model is unreliable and does not faithfully represent reality.
The warming of the 1930′s-40′s was natural, and whatever contribution of recent warming in the Arctic by CO2 is only trivial in that context.
Have not read all the responses but great article.
Have a question.
Is there a point that may be coming or past that the positive feedback of additional open water in the warming in the Arctic will be discernible.
This may be tangled up with warm additional North Pacific waterflow through newly unimpeded channels.
Both these should be accelerants to a slow consuming burn off of the ice pack in the Arctic. Is there a discernible point, maybe in a model, that includes reduced albedo in the summer, that might show an acceleration of melting above the average temperature increase curve for the region so that ocean warmth has an increasing role over atmospheric??
( yeah yeah not the clearest question but hey just off 30 hours of Australia to Canada over the pole. )
Paul Beckwith: “I would rather be the chess master that sees the pattern amongst all the pieces, consider the strategy and tactics that the whole board and the entirety of pieces dictates,and projects where the game is headed and what the other player Earth is liable to do,as opposed to being one of the pieces myself.”
This attitude is precisely the problem. The human brain is a machine for recognizing patterns, whether they are there or not. Unless we constrain our pattern recognition with empirical data, we will be spectacularly wrong. What is more, since we are rationalizing animals rather than rational ones, we will merely confirm our prejudices by finding patterns in noise.
Paul, I’ve no doubt you are a smart guy. But Freeman Dyson is a smart guy, and he is spectacularly wrong about climate change. Earth is the only chessmaster, and we are all just pieces on the board. The only difference is how much damage the pieces inflict on each other.
#200–Jim, the subject under discussion was allegedly ice-free periods in the Arctic in 1934 and 1953. While the data available does not allow a complete evaluation of the state of the ice in those years, it is more than good enough to rule out anything like an ‘ice-free’ status. Thus Gavin’s tag of “implausible” was not only justified, it was charitable.
If you wish to discuss climate models, that is a whole other question. But at least take notice that you are attempting to change the subject.
And on that subject, I will simply note that your assertion:
“The warming of the 1930′s-40′s was natural, and whatever contribution of recent warming in the Arctic by CO2 is only trivial in that context.”
…is just that–pure unsupported assertion; it doesn’t follow.
(If we grant for the moment that the ‘model doesn’t represent reality’, then there is no basis in anything you wrote for any attribution–either to the ‘natural’ causes you claim, or to greenhouse forcings.)
“I would rather “hand wave” and be correct rather than “mechanistic” or “statistical” and be wrong. Many scientists are like chess pieces on a chessboard, their knowledge and worldview is based on the given square that they occupy and the squares that they can legally move to.
I would rather be the chess master that sees the pattern amongst all the pieces, “
I’m sorry, I just can’t let this high-handed triteness pass.
Look, “hand waving” refers to empty posturing designed to manipulate opinion with obfuscation and portentous overtones of “beyond-the-beyond”. It is not synthetic or h*listic. On the other hand, contrary to popular postmodernist b.s., scientific practice is a flexible and creative endeavor. And it works.
As for chess, WTF! The skill set required to play chess at the masters’ level is intense but very narrowly “mechanistic”, patterns and all. You must be thinking of backgamm*n where lucky idiots can occasionally beat masters, and then spout baloney about why that happens.
Climate science is science. Science works. It works better than anything else we’ve got. Deal with it.
Some numbers on forcing (posted in reaction to the AMEG suggestion that of relaxing “pollution” [sic] rules for sulfates might be a wise move).
Note their timing–hearings open on the new EPA coal plant rule
“The simulated magnitude of hydrological changes over land are much larger when compared to changes over oceans in the recent marine cloud albedo enhancement study since the radiative forcing over land needed (−8.2 W m−2) to counter global mean radiative forcing from a doubling of CO2 (3.3 W m−2) is approximately twice the forcing needed over the oceans (−4.2 W m−2). Our results imply that albedo enhancement over oceans produce climates closer to the unperturbed climate state than do albedo changes on land when the consequences on land hydrology are considered. Our study also has important implications for any intentional or unintentional large scale changes in land surface ….”
(Are those reasonable numbers for the change needed in forcing?)
“Our results suggest that, in contrast to other proposals to increase planetary albedo, offsetting mean global warming by reducing marine cloud droplet size does not necessarily lead to a drying, on average, of the continents. However, we note that the changes in precipitation, evaporation and P-E are dominated by small but significant areas, and given the highly idealized nature of this study, a more thorough and broader assessment would be required for proposals of altering marine cloud properties on a large scale.” http://www.springerlink.com/content/9569172415150486/
Volume 37, Numbers 5-6 (2011), 915-931, DOI: 10.1007/s00382-010-0868-1
Albedo enhancement of marine clouds to counteract global warming: impacts on the hydrological cycle
G. Bala, Ken Caldeira, Rama Nemani, Long Cao, George Ban-Weiss and Ho-Jeong Shin
(Caldeira is listed by the AMEG as having contributed to their work; I wonder if he agrees with whatever it is they plan to propose sometime)
“… a relatively simple, environmentally acceptable, double-acting mechanism for increasing the earth’s albedo emerges. It is a low-level environmental intervention that enhances a mechanism already active in nature by increasing the foam fraction of the ocean surface. Bubble rafts increase the optical reflectivity of the ocean and when bubbles burst, they launch seasalt particles that loft and increase the number concentration of cloud droplets in the marine boundary layer, thus increasing the reflectivity of stratocumulus. A strategy based on recent research for producing microbubbles appears to be the best option for large-scale use.”
Picture the ocean covered with rafts of foamy bubbles instead of ice.
Imagine what that will do to photosynthesis in the upper ocean layers.
In figure 4d the anomaly appears, but at a different time (they state the X axis in that plot is arbitrary). This is explained in the adjacent column at the top of page 4 – assuming you’re using the Tellus copy and not a pre-print.
The point of this is that; the forced response should appear in all ensemble members as a consistent feature but incidents of internal variability should appear at different times or not at all*. Johanessen et al conclude that the consistent appearance of recent warming with GHGs simulated supports the interpretation that the current warming is a forced response to GHGs, of which the increase is overwhelmingly human driven. Whereas the appearance of similar warming events to the 1920/30s event at different times, with that warming event not being consistenly present in all ensemble members at the same times is evidence that it was an outcome of internal variability, not a forced response. Furthermore as Johanessen et al point out the spatial structure of the two warmings is different, a point also stressed by Overland et al, 2008, “”The recent Arctic warm period”, Tellus.
*See also Gillett et al, 2008, “Attribution of polar warming to human influence” wherein figure 1a shows the same behaviour.
Why do you persist in talking condescendingly to me like I was duped by false photographs. It was never the point of my argument and was something I myself said provided little weight to the discussion. The picture I referred to as creating the “speculation” of open water was not fabricated but is part of the naval archives, http://www.navalhistory.org/wp-content/uploads/2010/11/uss_skate_north_pole1.jpg Their caption along with the picture was “The only USS Skate (SSN-578) made submarine history on 11 August 1958 when it became the first submarine to surface at the North Pole.” The misinterpretations you want to focus on is merely the date of when that picture was taken. Whatever the date of the picture, it has a too limited scale to advance an argument one way or another, but you continue to drag this straw dog throughout the thread. Perhaps you lack any other ammunition.
If you want to discuss Arctic conditions and open waters, then we must address the natural warm temperatures that Arctic scientists clearly observed in the 1930′s and 40′s. We must be able to discuss how those warm water incursions that lay below the surface for 15 years can affect sea ice. Or how freezing winds can open the waters, as well as remove multi-year ice, built from converging winds, that resisted annual melting. CO2 radiative heating only contributed a trivial amount of warming and has had no impact on expanding Antarctic Ice. Much of the Arctic’s open waters in the west were created by winds off the coast of Siberia that were so cold that any added heat from CO2 would be meaningless. Read Rigor 2002. Changes in the PDO and NAO speed up the gyres and increase the flow of warm waters entering the Arctic . In the North Atlantic sector it is this inflow to the Barents Sea and subsequent feedbacks that Bengstonn 2004 refers to as maintaining open waters and Arctic warmth. Furthermore removal of ice not only allows greater heat flux but re-couples the atmosphere to the oceans thereby generate more turbulence that brings warmer waters to the surface. As Rigor rightfully asked “are warmer temperatures due to less ice, or did warmer temperatures cause less ice?” No one has yet to definitively proven the latter. As the PDO has gone negative, so have the warm incursions from the Pacific and the Bering Sea is now showing signs of growing sea-ice. Nature will soon reveal the power of CO2 versus oscillation in the next 20 years as those oscillations trend negative and deny the Arctic with warm waters.
But you do not discuss that science. instead yo choose to hang your hat on “debunking” the date that the Skate surfaced at the North Pole, like that proves anything one way or another. You are purposely obscuring the issues.
Jim Steele@209: “Why do you persist in talking condescendingly to me like I was duped by false photographs.”
From your comment #179: “Indeed, there is no way to truly compare ice coverage during the 1930′s to 40′s but the source of that speculation was pictures taken from submarines that surfaced at the north pole with considerable open waters.”
It’s not just that the date of the photograph is different than has been claimed. It’s that the photograph was not taken at the north pole. If you can show us any photograph of a submarine surfacing at the north pole in open water, please do so. Be sure to provide documentation of its location, because at this site we’re real skeptics, not fake ones.
As for refusing to discuss the science, you seem to be the one doing that. I’ve already pointed you to data for Arctic sea ice coverage which contradicts the claim that ice cover was anywhere near as low as today. You don’t seem to want to discuss that. I also pointed you to data for Arctic temperature which shows that it has warmed considerably over just the last decade, so that presently the Arctic is far warmer than it ever was in the 20th century. You don’t seem to want to discuss that either.
If you get the impression that people are treating you condescendingly, perhaps it’s because you have been evasive and mendacious. When you fail to acknowledge, let alone address, proof that your claims are false — what do you expect?
Whatever the date of the picture, it has a too limited scale to advance an argument one way or another
Bullshit. It’s clear she found a lead in the ice and surfaced in the lead, surrounded by pack ice.
FROM THE VERY PAGE YOU CITE:
USS Skate (SSN-578) hung below the Arctic ice like a matchstick suspended an inch from the ceiling of a large room. A knot of sailors in the control room stared intently at an instrument inscribing patterns of parallel lines on a rolling paper tape. The pattern looked like an upside down mountain range.
“Heavy ice, ten feet,”said one of the sailors.
Suddenly the lines converged into a single narrow bar. “Clear water!” the sailor called out.
A wrong move or a miscalculation would endanger the mission or even the ship. Calvert continued to peer through the eyepiece. When the top of the periscope came within sixty feet of the surface, he spotted heavy ice to the side. He flipped the prism to look straight up, but saw nothing except the same blurred aquamarine. Sweat appeared on his forehead as he felt all eyes in the control room bear down upon him. If the sub rose too slowly, it could drift away from the opening. If it rose too quickly and struck ice, the collision could tear open the pressure hull and send the sub and all ninety men on board to the bottom.
The submarine’s black hull stood out in stark relief against the deep blue of the calm lake in which the ship now floated. Beyond the lake, stretching to the horizon in every direction, was the stark white of the permanent polar ice pack. The officer who had climbed to the bridge with Calvert called the skipper’s attention to the port side of the ship. There a full grown polar bear was climbing slowly out of the water and up onto the ice.
Now what were you saying about the experience of the USS Skate not being sufficient to disprove claims that the North Pole was ice free in 1958?
I’m sure you read the entire page, Jim, not just the single line you quote.
Jin Steele @209
Who ever introduced this ‘straw man’ and what ever his age (1930/40s or 1959), he (the straw man) is no friend of mine. Can we please now shoot him dead and bury him?
Yes, the photo you link to @209 is a picture of USS Skate. The USS Skate did surface at the North Pole in 1959 as the photo caption says but the picture was not taken there.
The link below has pictures (below the graphs & maps) of the Skate at the North Pole in 1959. There is no open water that I can see. http://www.science20.com/chatter_box/arctic_ice_october_2010
Regarding your citing decade-old papers pointing out that the proximate cause of the loss of arctic ice isn’t solely due to warming air temps in the arctic, but rather warm water incursion, etc, well, yes, that’s the mainstream view and isn’t controversial. You have a point?
Mr. Steele writes on the 21st of April 2012 at 1:29 pm:
“CO2 radiative heating only contributed a trivial amount of warming…
“…winds off the coast of Siberia that were so cold that any added heat from CO2 would be meaningless.”
What do you imagine that the radiative warming due to CO2 over the rest of the globe is doing to the temperature of the ocean in the far north ? Oddly enuf, a new paper by Levitus et al in GRL answers that in Figure 3.
“…the flow of warm waters entering the Arctic .”
Do you imagine that the flow of warm water into the Arctic is not due to global radiative imbalance caused by CO2 ?
“Nature will soon reveal the power of CO2 versus oscillation in the next 20 years as those oscillations trend negative and deny the Arctic with warm waters.”
Why yes, you do! Very well: You predict that the loss of sea ice will halt and reverse over the next two decades. I have a counter prediction: that we will see a seasonally ice free arctic before two decades are done.
Now as to the Levitus paper: it is quite amazing to see that the extreme north Pacific and Atlantic keep warming in spite of the 5e19J/yr absorbed by the 300Gt/yr ice melt from PIOMASS or even the similar amount that it takes to melt Greenland at 250Gt/yr . Globally the oceans are warming at surface and at depth. I do not see how a perennial arctic icecap can survive very long.
The link below has pictures (below the graphs & maps) of the Skate at the North Pole in 1959. There is no open water that I can see.
No, no, she really did surface in a lead at the Pole in 1958. The problem is that the official account makes it clear that it was a small lead that was barely large enough for her to surface in, and that she had to surface very carefully after carefully searching for a suitable lead.
That’s why her sail was strengthened, and why subsequent nuke subs have strengthened sails: the only *reliable* way to surface in winter in the midst of the Arctic Sea is to smash through the ice.
The whole experience screams “those who claim the north pole [or pretty much anywhere else in the Arctic Ocean] was ice free in winters in the 1950s” is full of it. If the Skate’s experience supported such claims they wouldn’t've bothered spending the money to retrofit her sail, or to increase the expense of future subs by doing the same (sail and planes, actually).
Observations reveal external driver for Arctic sea-ice retreat
Internal variability as estimated from observations can’t explain sea-ice loss
Superposition of a linear trend and internal variability explains sea-ice loss
Observational sea-ice record shows no signs of self-acceleration
Dirk Notz, Jochem Marotzke
“The very low summer extent of Arctic sea ice that has been observed in recent years is often casually interpreted as an early-warning sign of anthropogenic global warming. For examining the validity of this claim, previously IPCC model simulations have been used. Here, we focus on the available observational record to examine if this record allows us to identify either internal variability, self-acceleration, or a specific external forcing as the main driver for the observed sea-ice retreat. We find that the available observations are sufficient to virtually exclude internal variability and self-acceleration as an explanation for the observed long-term trend, clustering, and magnitude of recent sea-ice minima. Instead, the recent retreat is well described by the superposition of an externally forced linear trend and internal variability. For the externally forced trend, we only find a physically plausible strong correlation with increasing atmospheric CO2 concentration. Our results hence show that the observed evolution of Arctic sea-ice extent is consistent with the claim that virtually certainly the impact of an anthropogenic climate change is observable in Arctic sea ice already today.”
dhogaza re:Take-home image for people like Jim Steele who like pictures unfettered with context.
I really appreciate how simplify things for me, but you really do need a tad more context to your pictures. What latitudes for example may be helpful. What stations were used and what were omitted. And what homogeneity algorithms did they run. NASA always gets the same shape for all its graphs. Do you think Bengstonn and others were deceiving us with their graphs that tell a different story?
Looks like a reply didn’t make it in? Try “Bergston 2004″
Appendix A. References. 2004. Impacts of a Warming Arctic: Arctic Climate Impact Assessment. Cambridge: Cambridge University Press. http://www.acia.uaf.edu.
CO2 radiative heating only contributed a trivial amount of warming [to the Arctic] and has had no impact on expanding Antarctic Ice.
With regards the Arctic: As Gillett et al and Johanessen et al show – in models without the anthropogenic increase of greenhouse gasses the Arctic warming does not occur, add the GHG effect and the warming occurs in all ensembles. This is also apparent in Wang & Overland’s 2009 study “A sea ice free summer Arctic within 30 years?” Figure 1 of that study is shown here, showing September sea ice extent vs time:
You can see that in all the models the natural forcing runs are level (grey trace) whereas the runs including anthropogenic forcings (coloured lines) decline. As I’ve shown, this is a common feature virtually all models, and I only say ‘virtually’ in case there is a model that doesn’t show this effect. So whilst the anthropogenic forcing is strongly amplified by processes in the Arctic, it is required to explain the changes in the Arctic.
With respect to Antarctic sea ice Zhang 2006 “Increasing Antarctic Sea Ice under Warming Atmospheric and Oceanic Conditions.” identifies a possible mechanism that explains the increase in that sea-ice due to warming and increase in downwelling long wave radiation. The warming being a secondary effect of increased GHGs, the increased downwelling long wave a primary impact. In essence Zhang proposes that the warming factors reduce the growth of sea ice which reduces ocean overturning allowing increased stratification of the ocean which in turn reduces ocean heat flux available to melt ice. Hence the sea-ice grows.
Read Rigor 2002…
As Rigor rightfully asked “are warmer temperatures due to less ice, or did warmer temperatures cause less ice?” No one has yet to definitively proven the latter.
I’ve read it, I’ve also read some 170 papers on the changes in the Arctic, it’s my hobby. As I’ve hammered home the point above – the changes in the Arctic don’t happen without anthropogenic forcings. And as I’ve also tried to inform you in post #208, there are two papers that find the 1920-30s warming is markedly different from the current warming. These papers were published after Rigor 2002.
Warm waters from the Atlantic are a factor, however as Spielhagen et al shows the recent influx of Atlantic waters is exceptional in the context of the last 2000 years. Coincidence?.
Warm waters from the Pacific are also a factor, however the recent influx and role in 2007 is not due to the PDO but the Arctic Dipole (AD) (Zhang J et al, Wang et al). And the AD has become the dominant mode of variability in the Arctic since 2003 replacing the AO (Zhang X). Coincidence?.
The warming in the Arctic reverses a long term cooling and is exceptional in the context of the last 2000 years (Kaufman et al). Coincidence?.
The recession of the Arctic sea-ice is exceptional in the context of the last 1400 years (Kinnard et al). Coincidence?.
The reason you like papers from the late 1990s and early 2000s is that then it was possible to view the changes as possibly due to natural factors. There has been a lot of further research since then.
Nature will soon reveal the power of CO2 versus oscillation in the next 20 years as those oscillations trend negative and deny the Arctic with warm waters.
Stop waving your hands around and be specific. I’ll start for you.
We know the AO/NAO hasn’t driven the warming and ice loss of the 2000s. It had a role due to increased ice fluxes through the Fram Strait in the early 1990s, when the AO/NAO was very positive. But since then it has gone neutral (ref). The PDO has been in a positive phase, now it is clearly going negative (ref), yet the losses continue – 2011 nearly matched 2007 despite the weather not being as favourable for ice loss. The AMO has been negative then gone positive during the period of ice loss (ref 3rd graph down), that is if we are to believe in the AMO at all (ref).
So where is the consistent pattern of coincident natural ‘oscillations’ and how do they generate such exceptional changes in the Arctic. Why didn’t they do so before? Why is it that the last time Arctic sea ice was in a worse state than now was in the early to mid Holocene, when an external forcing (insolation) was substantially higher than now? Doesn’t this suggest that such extreme and exceptional conditions are driven by external forcings like insolation, or indeed greenhouse gas emissions?.
Kaufman et al, 2009, “Recent Warming Reverses Long-Term Arctic Cooling.”
Kinnard et al, 2011, “Reconstructed changes in Arctic sea ice over the past 1,450 years.”
Spielhagen et al, 2011, “Enhanced Modern Heat Transfer to the Arctic by Warm Atlantic Water.”
Wang et al, 2009, “Is the Dipole Anomaly a major driver to record lows in Arctic summer sea ice extent?”
Zhang J et al, 2008, “The role of Pacific water in the dramatic retreat of arctic sea ice during summer 2007.”
Zhang X et al 2008, “Recent radical shifts of atmospheric circulations and rapid changes in Arctic climate system.”
Thanks, Hank. It’s in the references of the Annex you linked. The reason it was so hard to find is that “Bengstonn”–really “Bengston,” if this is the correct reference–is not the lead author. The correct citation appears to be:
Johannessen, O.M., L. Bengston, et al., 2004.
Arctic climate change, observed and modeled
temperature and sea ice variability, Tellus
SAT observations and model simulations indicate that the nature of the arctic warming in the last two decades is distinct from the early twentieth-century warm period. It is suggested strongly that the earlier warming was natural internal climate-system variability, whereas the recent SAT changes are a response to anthropogenic forcing. The area of arctic sea ice is furthermore observed to have decreased ∼8 × 105 km2 (7.4%) in the past quarter century, with record-low summer ice coverage in September 2002. A set of model predictions is used to quantify changes in the ice cover through the twenty-first century, with greater reductions expected in summer than winter. In summer, a predominantly sea-ice-free Arctic is predicted for the end of this century.
I’m still looking for “Bengstonn 2004″ — what’s that refer to?
Google Scholar: – “Bengstonn 2004″ – did not match any articles.
So I have no idea what you’re looking at, Jim. Sorry, but this is the reason for citing sources. What’s your source?
Could it be this?
Johannessen OM, Bengtson L, Miles MW, Kuzmina SI, Semenov VA, Alekseev
GV, Nagurnyi AP, Zakharov VF, Bobylev LP, Pettersson H, Hasselmann K,
Cattle HP (2004) Arctic climate change: observed and modeled temperature and
sea-ice variability. Tellus 56(A):328-341
Jim, when you post these claims and don’t tell us where you’re getting them, it’s a snipe hunt — highly entertaining for the snipe, but not helpful for the conversation.
Where are you getting the 1930s and 1940s Arctic submarine story?
Where are you getting whatever the 2004 paper is?
If all you have is a second- or third-hand anecdote, fine, but WHERE IS IT?
We can look stuff up, given the least clue about what you’re relying on.
And, Jim, no “thank you” for your being skewered on the USS Skate’s experience not being sufficient to argue one way or another about the north pole being ice-free in the late 1950s, now that it’s been exposed as bullshit for 1958 by your very own link and 1959 by a photo of the ash-scattering ceremony?
If you can’t bring yourself to say “thank you”, a sincere “I’ll never lie about this again” would be sufficient.
You can make the same statement regarding arctic temps over at tamino’s after you read the article and thank him (over there) for his excellent analysis.
NASA always gets the same shape for all its graphs. Do you think Bengstonn and others were deceiving us with their graphs that tell a different story?
Not only NASA, but others including some of the more intelligent skeptics that inhabit lucia’s blog, “The Blackboard”.
It’s an interesting mindset … “NASA always gets the same shape” (therefore they’re wrong).
As far as the paper you continuously mention, where’s a link? We have no idea as to what it says. Even if you represent the paper’s results correctly, though, there’s only one reason that you’d pin your faith on a single paper rather on the vast amount of work done by many other scientists that are in broad agreement on a different conclusion:
When one paper’s an outlier, it’s usually wrong, especially if it’s an older paper (2004) whose conclusions have not been supported by more recent work.
However, since you apparently can’t provide a link to the paper’s contents, I can safely assume that 1) it doesn’t exist or 2) it doesn’t say what you think it says or 3) it’s been thoroughly refuted or outdated by subsequent work.
Given that your link to the naval history account of the USS Skate’s surfacing at the north pole skewered your claims about the possibility of the north pole having been ice free in 1958, I’ll take door number two from the choices above.
“The huge warming of the Arctic that started in the early 1920s and lasted for almost two decades is one of the most spectacular climate events of the twentieth century. During the peak period 1930–40, the annually averaged temperature anomaly for the area 60°–90°N amounted to some 1.7°C. Whether this event is an example of an internal climate mode or is externally forced, such as by enhanced solar effects, is presently under debate. This study suggests that natural variability is a likely cause, with reduced sea ice cover being crucial for the warming. A robust sea ice–air temperature relationship was demonstrated by a set of four simulations with the atmospheric ECHAM model forced with observed SST and sea ice concentrations. An analysis of the spatial characteristics of the observed early twentieth-century surface air temperature anomaly revealed that it was associated with similar sea ice variations. Further investigation of the variability of Arctic surface temperature and sea ice cover was performed by analyzing data from a coupled ocean–atmosphere model. By analyzing climate anomalies in the model that are similar to those that occurred in the early twentieth century, it was found that the simulated temperature increase in the Arctic was related to enhanced wind-driven oceanic inflow into the Barents Sea with an associated sea ice retreat. The magnitude of the inflow is linked to the strength of westerlies into the Barents Sea. This study proposes a mechanism sustaining the enhanced westerly winds by a cyclonic atmospheric circulation in the Barents Sea region created by a strong surface heat flux over the ice-free areas. Observational data suggest a similar series of events during the early twentieth-century Arctic warming, including increasing westerly winds between Spitsbergen and Norway, reduced sea ice, and enhanced cyclonic circulation over the Barents Sea. At the same time, the North Atlantic Oscillation was weakening.”
Sorry I’ve not really paid much attention to this issue of what paper is Bengtsson et al 2004 as mentioned by Jim Steele in post #179. As can be seen from my reply to him, post #184 I’ve known precisely what that paper was all along.
Yes Hank, you’ve got it, and you’re quite right – no surprises although it is interesting nonetheless. The paper basically proposes a mechanism for the Arctic warming of the 1920s and 1930s, it supports the idea that what is going on now cannot be naively used to ‘excuse’ GHGs from what is going on now.
1. The anomaly they’re studying (arctic warming of 1.7C from 1920-1940) matches the amount of warming for the same period shown in Tamino’s analysis linked to above. If Jim rejects the last few decades of that analysis he’ll have to explain why the analysis matches his beliefs for 1920-1940 (and the mainstream reconstructions). It would be fun to see him do so at Tamino’s blog.
2. The paper does not suggest that the anomaly in 1940 was higher than the anomaly when the paper was written (2003). Not sure why Jim cited the paper as evidence for his claim as it doesn’t appear to address the question.
3. I think Jim’s arguing against a strawman view of climate science, i.e. the typical one that science ignores natural variation, changes in solar activity, etc in a belief that only changes in CO2 can affect climate. That’s silly if that’s what he believes science says.
4. The paper states that the warming seen in 1920-1940 is about what’s expected over the next few decades due to increased CO2 forcing. ON TOP OF the warming already seen when the paper was written (2003), when it was already warmer than the arctic than in 1940.
5. As is usual when a denialist quotes a mainstream paper claiming that it challenges the scientific consensus, the paper does no such thing. The authors accept mainstream views on climate sensitivity, indeed, one of their arguments for natural variability being the cause for the 1920-1940 warming is that if increased CO2 forcing was the cause, then climate sensitivity to increased CO2 must be far higher than the consensus range. In other words, their explanation based on natural variability for this period of time *supports* the consensus view on climate sensitivity to increased CO2, if anything.
Changing the subject is a fake skeptic’s stock in trade. You will never pin them down to statements they made because they will blame the questioner for being “condescending” or some such.
This is a serious website where some of the world’s best scientists are willing to engage with questions, even silly ones. Rather than come in with a chip on your shoulder big enough to sink you through all that ice, try an open mind and some true skepticism.
It’s not painful to look at the truth. It’s unfortunate that so many people seem to need to come in with attitude and leave in ignorance when such a wealth of material is available to the interested reader.
The rest of us, and those not speaking up, are learning more from this conversation about how people with stiffened bias are unable to take the fearful step toward reality.
Chris Reynolds, thanks for that link. The text-only version I skimmed doesn’t have the figures.
Shame on you! Figure 1 in the paper you worship shows that by 2000 arctic temps were much WARMER than the peak in 1940! How DARE you to cite it in support of your claim that “the temperatures in the Arctic during that time were remarkably similar to this current period and the subject of several peer reviewed papers”.
That’s a pants-on-fire there, Jim.
Of side interest, Tamino’s analysis of arctic temps look *remarkably* like Bengtsson et al 2004′s Figure 1, except for the fact that Tamino’s runs out another decade because, well, time has gone on (and temps have continued to rise).
Here’s what I predicted earlier, before the paper had been rediscovered by Hank (though Chris, as he says, was well aware of it dozens of posts ago and already skewered Jim):
However, since you apparently can’t provide a link to the paper’s contents, I can safely assume that 1) it doesn’t exist or 2) it doesn’t say what you think it says or 3) it’s been thoroughly refuted or outdated by subsequent work.
Given that your link to the naval history account of the USS Skate’s surfacing at the north pole skewered your claims about the possibility of the north pole having been ice free in 1958, I’ll take door number two from the choices above.
It looks like my choosing #2 – “it doesn’t say what you think it says” – basing that choice on your misrepresentation of the USS Skate’s surfacing at the north pole in 1958, was correct. Though I was overly polite in predicting misunderstanding rather than, as I suspect, outright dishonesty.
‘Fess up, Jim.
Your credibility has vanished, just in case you’re wondering.
NASA always gets the same shape for all its graphs. Do you think Bengstonn and others were deceiving us with their graphs that tell a different story?
You really, really, need to apologize for this statement since figure 1 in Bengtsson et al 2004 clearly does *NOT* tell a different story. And to say this *after* Chris Reynolds posted a link to the full paper and stated the truth about the contents?
You can get away with this crap at WUWT but not in the real world.
Well, as soon as Jim wants to tell us where he got the mistaken ideas — submarines surfacing through the ice in the 1930s and 1940s, and this notion that one paper says something that’s not in it — we can look at the source and see if he misread it or it misinformed him.
I’m betting on co2science.org — ‘fooled me once’ “source” for many people.
I followed your link to Notz and Marotzke (#223). Using extent data up to 2010, they do not directly address the claim that the decline of extent in Arctic Sea Ice is linear vs the claim that it is accelerating. They address and dismiss self-acceleration via the ice-albedo effect. The section on external drivers dismisses all candidates for which data is available (solar irradiance, indices for AO and PDO, volcanoes, etc.) as being the cause of the downward trend leaving only atmospheric CO2 concentration as a plausible explanatory variable. They do not even admit the possibility of an unknown or unmeasured external driver leading to an acceleration of declining extent.
The Sep average extent data from NSIDC for 1979-2011 has a maximum in 1996. The slope from 1979 to 1996 is -36,000 sq km. The downward slope for 1979-X for X>1996 increases every year for 15 years – acceleration for 15 years in a row. Is that a linear trend?
This article by Axel Schweiger, Ron Lindsay, and Cecilia Bitz and the comments that follow give the strong impression that the Climate modeling community insists that this time series has a linear trend and will shout down anyone who disagrees with them. I do not understand this mindset that says, “Until we can find a way model reality, everyone else should ignore it.”
Jim, if this is the cite you’ve been hinting at in your email and claiming was being censored — now that I can finally look at where you got your info — that cite is from January 1993!!
You could just have posted the actual cite and saved a whole lot of questions about where you were getting your statements — which you made sound like they were current information, mind.
I still don’t find the source where you got the story about submarines surfacing in open water in the Arctic Ocean in the 1930s and 1940s. Have you posted it _anywhere_? I was sure I could find anything at Spencer’s that you would claim was censored at RC.
Email still welcome. But you’ve got to give answers to support what you claim to be credible.
PPS — and, Jim, the scientists here who wrote the main post for this thread have cited that 1993 paper in their own published work. Overall it’s been cited 122 times in 19 years that Scholar finds. Really, it wasn’t news.
One must remember that Bengtsson, et. al., were only postulating a mechanism that could have caused the Arctic warming and sea ice reduction of the early 20th century. Their models showed that the mechanism is plausible.
The idea that the Arctic was “ice-free” at this time seems “implausible,” to quote Gavin. The data shown from Johannessen shows that while a similar temperature rise occurred in the Arctic in the early and latter 20th century, the latter has resulted in a higher temperature (as stated by several posters). The models also suggested that the rise in Arctic temperatures at the time, corresponded with the observed reduction in sea ice. I would be curious as to how their sea ice reduction from the early 20th century compares to the recent reduction.
> Dan H.
> … I would be curious as to how their sea ice reduction from
> the early 20th century compares to the recent reduction.
Chris posted a link to it:
“– no surprises although it is interesting nonetheless. The paper basically proposes a mechanism for the Arctic warming of the 1920s and 1930s, it supports the idea that what is going on now cannot be naively used to ‘excuse’ GHGs from what is going on now.
Look at the papers that have cited it — quite a few cites since it’s almost 20 years old. Note the names of the authors and compare them to the cites for the main post here.
It’s odd (or not) to see such fascination with a paper mistakenly claimed to show something it doesn’t, that’s nearly 20 years old, that has no surprises in it, and that’s been part of the discussion in the field for, well, almost 20 years.
Something special about this one for somebody. I wonder where it’s popular? Who’s the one originating the misstatements about it? And why do y’all trust whatever source you’re relying on to believe the misstatements?
It mus be discouraging to scientists to see how aggressively people misunderstand, misstate, and confuse attempts to discuss their work.
If only we had a two-track commenting system — one for real scientists and invited students interested in learning, and a shadow track for kibitzers.
If someone competent to describe how the software would work well enough to guide a programmer would put it on Kickstarter or one of the many new similar science funding sites — I’d toss money at the idea. Oh, John?
I scanned both the 2004 papers. The most interesting thing for me was in (IIRC) the *Bengtsson*, where they proposed that the main physical factor in the ‘variability-driven warming/SI decline’ of the ’30s was a persistent circulation pattern resulting in a ‘clearing’ of the Barents (or Barentsz, if you prefer), which in turn fed back into a larger warming. Of course, that result is now 8 years old; I don’t know how well it’s stood up.
But it’s interesting, because currently there’s a rather anomalous clearing of the Barents as well–albeit on a shorter timescale. We’ll see what happens…
You really need to follow the discussion better. Links to the Bengtsson paper, which we are discussing, have been presented in posts #233, 234, 235, and 250, along with links to the Johannessen paper in #221, 228 and 230. It really is not that hard to follow the discussion once you have read the relevant papers.
Ray L, I meant permafrost and ESAS clathrates would have been extremely cold at the beginning of the Holocene, while now they’re making a move towards slushy. Assuming we do at least as bad as the early Holocene, then our inferior starting position means we could be at risk of a significant methane release.
On ice volume, both from a linear trend and from computer models, sea ice is likely to recover a bit for at least a decade, which could frame the debate for years to come.
But why is ice so low? The weather has been ice-friendly, yet the volume remains record-breakingly low. Why? This seems like an easy way to falsify the exponential hypothesis.
I didn’t ‘promptly’ do it, it took a few days before I woke up and paid attention to the other discussions here. Had I done so sooner…
Now this is the interesting discussion. But for the assimilating models (PIOMAS & NPS), there really wouldn’t be much talk of an imminent sea-ice free Arctic. There was 2011, which very nearly met 2007 despite weather not really being conducive to ice melt, certainly not as much as 2007 itself. Otherwise, post 2007 the sea-ice seems to have settled into a new (pseudo) equilibrium, it hasn’t undergone a rapid succession of crashes.
Then there’s Maslanik’s work with the Drift Age Model. http://nsidc.org/arcticseaicenews/files/2012/04/Figure5.png
And Nghiem’s findings of a massive crash in multi-year sea ice. http://farm5.staticflickr.com/4100/5610908526_7906568338_o.jpg
Maslanik doesn’t find the same precipitous drop as Nghiem, this is because Maslanik counts mixed ice in with perennial, whereas Nghiem discounted it. Considering the two approaches, what they show is that the pack has now transtioned to a seasonally sea ice pack, with a residual amount of multi year ice. This residual is a logical consequence of there still being sea ice growth in the winter, and a significant area of ice at the end of the summer.
These and other issues present a picture of an ice pack that’s now transitioned from largely multi-year ice in a large mass to mainly first year, with multi year becoming more limited in region (off the Canadian Archipelago) and spread out when it leaves that safe zone.
So what is going on? Observations support the idea that we’re in a slow transition with the ice being in a pseudo-equilibrium state of mainly first year ice. While the assimilating models, our only current option for widespread volume indication, imply a precipitous crash of volume.
Short of actual thickness/volume data, is there any way to cut through this issue and clarify what is going on?
“Short of actual thickness/volume data, is there any way to cut through this issue and clarify what is going on?”
I think I can.
Professor Peter Wadhams, member of AMEG, expert on Arctic sea ice and a reviewer for the IPCC AR5 report, says that the PIOMAS data is based on actual thickness measurements.
[Response: This is not true. Please read the top post. - gavin]
As the sea ice retreats, the water absorbs more sunshine and warms faster. This means that the sea ice formed in winter is thinner and melts faster in summer. As a result, the sea ice volume at its annual minimum has declined 75% over the past three decades. Although the sea ice extent has held up since 2007, the thickness has declined; but the extent cannot continue to hold up indefinitely while the thickness continues to decline. Wadhams expects a collapse in extent within the next few years.
Note that, from the guest commentary at the start of this blog, we read:
“A different class of predictions are based on simple extrapolation using historical sea ice extent, concentration, or volume. An example is included in the materials presented by the so-called ‘Arctic Methane Emergency Group’ [AMEG] who show extrapolations of PIOMAS data and warn about the potential of a seasonally ice-free Arctic ocean in just a few years.”
However, the commentary concludes:
“But when will the Arctic be ice free then? The answer will have to come from fully coupled climate models.”
Wadhams and the AMEG argue that observations are more to be relied on than models, especially when the models have proved unreliable in the past.
[Response: There are no observations of the future yet available, and extrapolation - particularly using exponentials - is fraught with over-confidence and almost certain error. We are well aware of what you are doing to get your result, our complaint is that you haven't justified why it makes any sense. - gavin]
BTW, Wadhams predictions on sea ice were challenged by Prof Julia Slingo of the Met Office’s Hadley Centre, at the hearing of the Environment Audit Committee on “Protecting the Arctic”. He has written a robust rebuttal, which will shortly be in the public domain.
“Arctic expert, Professor Peter Wadhams (UK), said in November 2011 that the summer sea ice is on track to be virtually gone by 2015.” (No cite)
and below that
“The Arctic Catlin Survey …. results (of direct ice thickness measurements by bore holes coupled with historic data) in October 2009, Professor Wadhams said, …. supports the new consensus view that the Arctic will be ice-free in summer within about 20 years. (CNN)” (No cite; what consensus statement, by what group or organization, where published and when?)
and below that
A duplicate paragraph.
Looking for “Catlin Survey” — nothing in Scholar; the “Catlin Survey” is mentioned as an anecdotal unpublished source thus:
“… anecdotal in-situ observations in spring 2009 [SEARCH Sea Ice Outlook, unpublished, 2009; CATLIN Arctic Survey, unpublished, 2009].”
Well, with the global oil exporting countries on track to consuming all the oil they produce by 2025-2030 the rest of the world will be back in the dark ages well before we get an ice-free Arctic. The only knowledge we will have about conditions up there will from stories of distant places from the odd wind-powered whaling ship that ventures through Bering Straight.
As global communications blink out in the post-oil era the havoc an ice-free Acrtic will have on global climate (and vice-versa) will only be evidenced as the seas rise, and where the rain falls or the winds blow, or not.
We will huddle behind our shutters knowing we have unleashed a tiger, but powerless to stop it. Oh darn.
I followed the Catlin Ice Survey – kind of a hike with hardships (British), not meaning to belittle it – seemed fraught with difficulty, as all work in that part of the world would naturally be – a few years back. Fascinating stuff.
I seem to remember some issues with who was funding it, but as far as I could see it was a gallant effort. Of course as with any appearance genuine physical evidence, the deniers were all over it to discredit.
I should, seeing where I’m saying this, follow through, but am very busy so will just contribute this anecdotal note FWIW.
Comment by Susan Anderson — 24 Apr 2012 @ 10:04 PM
Oh, and I think their diary was published on the BBC at the time. (Catlin)
Comment by Susan Anderson — 24 Apr 2012 @ 10:05 PM
There’s presumably a data collection and papers either published or being written; I haven’t found them. There are a lot of different web pages out there for Catlin’s Arctic investigations, different each year. I found hints; I’m sure someone can find the science. I think this is just obscured because it’s being presented in corporate PR format, which means to be informative and probably is, for those who like that kind of thing.
“This endeavour will provide a surface-based dataset, which will then be made available to scientists. Its data will be used to improve the accuracy and reliability of supercomputer models forecasting the timing of the disappearance of the sea ice ….
… the supercomputer model developed by one of the world’s leading research teams at the US Navy’s Department of Oceanography, which focuses on the rate of the sea ice’s declining volume based on ice thickness estimates (as opposed to shrinkage rates), indicates sea ice loss within dramatically less time …” http://www.catlinarcticsurvey2009.com/science
Thanks, I was made aware of that article and the graphic at Neven’s after posting the above. It still doesn’t answer the question of the reality of the last two year’s Spring volume losses. But it does instill confidence in the overall PIOMAS trend.
That has however to be considered against findings such as those by Haas, to which Hank linked in #264. That paper finds:
The data provide detailed insight into ice thickness distributions characteristic for the different regions. Comparison with previous EM surveys shows that modal thicknesses of old ice had changed little since 2007, and remained within the expected range of natural variability.
Which seems to be the case from my amateur analysis of what little observed thickness data I can find for the 2010/2011 period. Although I’ve not been able to find enough to get a broad view of the Arctic, and some data such as Buoys suffers from an observational bias – more substantial floes of ice are chose for the placement of buoys.
However now Cryosat is up and running some of this uncertainty should start to be resolved.
I don’t think you’ve cut through the issue at all. Yes, as Stroeve et al 2011 argue, increased open water formation increases the ice albedo effect. But let’s not get things out of proportion.
Whilst there has been a continuing loss of thick multi-year ice (Maslanik – drift age model) after the precipitous drop Nghiem 2008 revealed using QuikScat: This is in line with the arguments of Bitz & Roe – thicker ice thins faster. So once again we’re thrown back on the precipitous drop of volume shown by assimilating models. But this doesn’t necessarily mean that behaviour will continue to zero. Since 2007 we’ve seen continued losses of volume whilst the area has seemed to stabilise somewhat, by this I mean that 2007 didn’t unleash a succession of crashes as might be expected using the simple reasoning of ice albedo feedback. What has happened is a continuation of loss of older thicker ice, with another apparent stabilisation, this time in terms of ice up to four years old.
That there haven’t been further crashes is important because it is telling us something about the processes at play, and ice-albedo is not the only player. In recent years there have been prominent Autumn and Winter near surface warming anomalies (NCEP/NCAR) which Screen and Simmonds interpret as newly open ocean heating the atmosphere. The same process of heat loss is seen in the Tietsche et al modelling study in which ice recovers after its specified removal from the modelled ocean, in that model study the heat loss leads to a recovery of the ice to its equilibrum level. Although as Kevin O’Neill has pointed out on this thread in the real world the reported volume loss of PIOMAS is at odds with Tietsche et al.
Another factor of note is that there is currently vigorous growth of FY ice during the winter. To attain a virtually sea-ice free state substantial amounts of this FY ice would need to melt out completely. I’ve yet to read anything that explains how this might happen. The nearest I’ve seen to evidence of such a process are the Spring melts of the last two years as revealed by a simple examination of the PIOMAS volume data. But I don’t know what the process is, and it’s yet to be seen whether there will be a repeat this year. If you need references for the papers I reference please ask and I’ll give better citations.
So we have a situation in which the more the ice recedes the more of the energy gained during the summer is lost and the more rapidly thin ice grows in the open water. So I’m not persuaded by the “rapid camp’s” arguments, the only thing that’s given me concern you might be right are the massive Spring volume losses of the last two years. If this repeats this year then I’ll review my position, but at present I think a September extent of below 1M km^2 is likely in the latter part of the next decade, and probably won’t become a regular event until into the 2030s.
All this said, I dislike your organisation’s presentation, think you overstate certainty, and that you don’t use sources correctly. On the latter point on this page you quote Stroeve et al (PDF).
The most recent published review of the science finds “the system may be poised to undergo rapid change” (The Arctic’s rapidly shrinking sea ice cover: A research synthesis, Julienne C. Stroeve, 2011).
However you do not include the closing paragraph of that paper which follows the line you quoted:
However, given the shortness of the available sea ice extent time series, the apparent steepening of the downward September trend may not be sustained. Climate model simulations reveal periods of rapid ice loss are often followed by a temporary recovery. Given natural variability in the coupled ice–ocean–atmosphere system, a few years of sea ice recovery, such as evident between 2007 and 2009, should come as no surprise.
I don’t see this as a negligible caveat, and from my reading of that paper I don’t think their idea of ‘rapid change’ is the same as yours.
I drew a blank with Catlin Arctic Survey too. You’ll find some links to sea ice thickness data on my blog’s most recent ‘Miscellanea’ post. If you want a spreadsheet with Candain Arctic Archipelago thicknesses just ask there and I’ll post my email address for you. Thanks for the admirable searching, as always, the Haas paper was new to me.
I find that artic ice exent is dominated by northern hemisphere land temperatures 3 to 12 months previously, with the greatest impact for temperatures 5-10 months earlier. If this is correct, than sea ice will be much greater this summer than in recent years because northern hemisphere temperature anomalies have been low this winter.
Chris, in my amateurish way, I have wondered whether there may be a bit of a slowdown in the rate of ice loss as the oldest ice melts. My reasoning was that, iirc, black carbon has played an important role in the ice loss by changing albedo. If the old ice melts year after year in the way large banks of ice melt in the spring around here–without significant runoff from the surface–you get darker and darker surfaces as the melt proceeds. This process should accelerate over time, with years-old soot coming to the surface and making it ever darker and more heat absorbent, until all the ice is gone.
But new ice would only have this years soot burden to alter its albedo, so would perhaps be ably to resist this accelerating albedo-shift-driven runaway melting.
But since this is just my own armchair theory, I would be happy to have holes poked in it.
On the losses over the last two springs, has that mostly been through physical transport through the Fram Straight?
(reCaptcha: fastruag duobus–sometimes I just love the absurdity of these strings of letters)
T. Marvell @276
I did a quick plot of Sept Arctic Sea Ice Extent onto NCDC NH land temp anomalies & didn’t see anything that would encourage me to use such temperatures to predict this summer’s ice extent.
Looking at warm episodes, 1990, 1995 & 2007 appear to conform with what you say having low ice. But this was not the case for 1981, 1998, 1999, 2000 or 2004.
Also 2008 & 2010 were low on ice but not warm.
The opposite (cold temps to predict high ice) worked better but only by lenient treatment of time lags, shortened in 1992 & 1996 while lengthened in 1994 & 2001. 1985 was also cold but with the ice nothing unusual. 1980 was high ice but normal temperatures.
So in 16 years, only 7 fit your assertion & 4 of those requiring time lag adjustments. That makes me rather sceptical about your predictor of summer sea ice.
Despite its popularity in public discussions, I’m not convinced black carbon (BC) is a major factor. For example, see the inline reply by Dr Schweiger on post #28 above. From the paper he links to:
The BC content of the Arctic atmosphere has declined markedly since 1989, according to the continuous measurements of near-surface air at Alert (Canada), Barrow (Alaska), and Ny-Alesund (Svalbard). Correspondingly, the new BC concentrations for Arctic snow are somewhat lower than those reported by Clarke and Noone for 1983–1984, but because of methodological differences it is not clear that the differences are significant. Nevertheless, the BC content of Arctic snow appears to be no higher now than in 1984, so it is doubtful that BC in Arctic snow has contributed to the rapid decline of Arctic sea ice in recent years.
Suspecting inceased Fram Strait export having a role in the volume losses seems reaonable. There is a recent paper that gives Fram Strait export figures for the period in 2010, I don’t have figures for Spring 2011. The paper concerned is “Recent wind driven high sea ice export in the Fram Strait contributes to Arctic sea ice decline” by Smedsrud et al. http://www.the-cryosphere-discuss.net/5/1311/2011/tcd-5-1311-2011-print.pdf
Figures 4 and 7 show the recent activity and longer term trend respectively, in the context of recent years Spring 2010 doesn’t stand out. Although note that those are in area, not volume. I’ve not got time to read that paper in its entirety but it doesn’t refer to volume.
Catlin scientists are congenial and very friendly. Try contacting them by E-mail.
Predicting sea ice extent is easy if you can mentally calculate wind variations, momentum, sea currents, multi year ice compression ratios, tidal synergy with weather patterns, the AO, the temperature of ice sea water and air, how cloudy it will be, salinity, pycnocline convection rates, sea surface to air interface, CO2 exchange, ice thickness distributions…..
Piece of cake!, morceau de chocolat..
I predict greater surface salinity, much earlier melt, great adiabatic events at sea surface to air interface, wide early thousand lead expansion events coinciding with at start clear than very cloudy air, a surprising near ice death experience at the North Pole because the North Greenland subduction zone is already very fluid. All time minimum to be exceeded only to be stopped further by clouds. By the way the howitzer in prediction, sun disk expansion comparisons, projects a warmer temperature gain than summer winter 2010.
But sea ice has so many variables, extent is not so easily foreseen. But unlike geologist shy about trying to forecast earthquakes, if we don’t try to do so, we will never understand the subject at hand.
I have predicted that artic sea ice extent this summer will increase greatly because sea ice extent is greatly affected by past land temperatures, which have been unusally low since November (My 279, and responses 279 & 280).
I use NOAA temperature data: http://www.ncdc.noaa.gov/cmb-faq/anomalies.php#anomalies
So far I have only used ice extent data. I have not been able to get monthly data for ice volume. Can anybody help me get it? Daily figures don’t help.
The impact is about the same when using the data series for world-wide land temperature & for northern land temperature (most land is in the north). The impact is lagged. That is, temperatures today affect ice some 3 through 12 months into the future, with the largest impact 5 to 10 months. To estimate the impact, one has to factor in the temmperatures for all these 10 or 6 months.
This conclusion comes from regressing ice extent (monthly anomalies) on lags of land temperature (monthly anomolies), with the variables differenced. The results are very strong statistically (prob. lt .00001). Global and hemispheric ocean temperatures have no discernable impact on artic ice extent, other than through its impact on land temperature.
Land temperature account for about 60% of the variance in sea ice extent, which is an extremely high figure in the world of statistic.
The impact is much stronger for summer ice extent than winter ice extent (that is, summer land temperatures don’t have a big impact on winter ice).
By forecasting more sea ice this summer, I am going against the grain; the posts here mainly assume a downard trend (though of course one year does not change in trend). But, by now the sea ice increase is old news. Artic ice extent through yesterday has climbed greatly compared to recent years: See: http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png
And historically the amount of sea ice at this time of year has foreshadowed the summer extent.
So, in saying that sea ice will be much more extensive than in recent years, I’m probably just stating the obvious. But I am giving a reason for the change, which might not have been evident.
I am continuing to research this topic. The next step is pin down the magnitude of the relationship, which would permit a specific prediction of summer sea ice exeent for months April to September.
T. Marvell @283
We appear to be using the same data but then obtaining entirely different results.
My comment @279 was based on examining this graph here. A plot of red squares & blue triangles against each other x/y does give a correlation but it entirely disappears if the ice & temp data is detrended. So I remain more than a little mystified by your assertion of a strong correlation.
282, Jim , is OK to be skeptical, but its irrelevant, what will happen will happen. How it happens is what matters. T. Marvell is basing his estimate on the very same ice we look at. Which one looks at the evidence better than the is important, only to be settled come late September. Cloud coverage is the biggest player in this case, without will make a great melt, or if not, totally save sea ice extent from collapsing further. Closely followed by temperatures, salinity, ice thickness and so down a rather large list of variables.
T. Marvel didn’t monitor or forgot to remember that during entire winter Cyclones whisked over Spitzbergen week after week towards the Arctic ocean. Thickness from the start should be less. Arctic first year ice seems not recovering to average, this means that any melt season may exceed 2007 minima. given that 2007 like multiple weather features are repeated, it is certain that the Pole will have some vast open water near by.
Salinity is also a huge factor, there is a significant salt content difference in First year ice melting and old multi year ice. This favors a greater melt or similar to 2011. What was astounding about 2007 was the quick melt of Multi year ice, since 2012 has a whole lot more 1st year ice, any weather conditions approaching 2007 will lead to my estimated result.
As this article suggests, the melts are not linear, ice melt sensitivities are huge, but we have already a very good idea of what will follow, the chances of T. Marvel being right not so good. But I worry about whether I am missing something obvious, if I did my projection was based on errors, and the extent will be more normal. But I never ever mess with sun disk projections, it will be hot, something which melts ice.
Re monthly volume, why not just use 12 X 30 day periods and ditch the 5 remaining days? It’ll have a negligible effect and will give as near as damn it monthly figures. In any case PIOMAS volume has every year 365 days, so I’ve adjusted area and extent observations to match that format, I’ve not gone the other way. So the spreadsheet I use (5Mb – Excel – every day from 1979 to 2012 area/extent/volume daily anomalies and subsequent pages such as thickness) would need massive modification to address this, and I’m sorry but I can’t spare the time right now.
I suspect MARodger has hit the nail on the head, if you don’t detrend two series with trends you’ll get large correlations that aren’t really as significant as statisitics based on a staionary series will suggest. Before looking for correlations, lagging, etc you really need to detrend. If the corelation exists in reality it’ll still be there.
Concerning my post 283 on the connection between land temperature and ice extent – Probably what is going on is that colder winters create more ice, which takes longer to melt. Seems obvious.
There are bound to many other factors affecting ice extent (see Davidson 287), but that does not rule out a large role for land temperature.
MARodger (#284) Graphs are hard to interpret, but to me there is a connection more often than not. The key here is changes, whether there is a connection between declining temperatures and more sea ice, which is hard to see in a graph. Since there are other factors involved, one would not expect a clear match on the graphs. Also, I find that the major impact is spread over 6 years, beween 5 and 10 years previously. You used a 3 month rolling average displaced 7 years. It would be better to use a 6 month rolling average, displaced 9 or 10 years.
Reynolds (288) – As you said, estimating monthly sea ice volume would be a lot of work. PIOMAS should do it if they want their work to be useful. Most climate data are published in a monthly format.
About detrending the time series – I do that. The variables are first-differenced (current month value minus the prior month variable). The variables are I(1), so regression in levels would make no sense. Also there would be a huge collinearity problem since I enter a lot of lags. But your raising this issue makes me question my statement earlier that temperature explains 60% of the variance in sea ice. That calculation was based on levels data, and is thus incorrect.
At the suggestion of Reynolds (288) I constructed a montly ice volume data series from the PIOMAS data set. The results are very similar to those when using the ice extent data set. That is lower land temperatures are followed by more ice volume several months later.
The ice volume data series is a bit odd. I use anomalies (e.g.,ice volume less the montly mean for the volume over 1980-2011) and then take differences (substrct the prior period anomaly from the present anomaly). The regressions contain lagged dependent variables. With nearly all variables I’ve ever used, including ice extent and temperatures, the lagged dependent variables have large negative coefficients, since changes one period tend to lead to “movement to the mean” in the next period. But when using ice volume as the dependent variable, there are large positive coefficients on the lagged dependent variable. It looks like the variable is constructed by starting with prior period values and adjusing them (this could be for only one element of the ice volume estimation), rather than taking independent measurements each time. This can cause data estimates to snowball, and it might account for the apparent accellerating decline of the ice volume time series.
287 Wayne, actually, I used the word “skeptical” in the bad way. I too have no mental qualms with the idea of a new record. However, the OP shows that the best no-weather-known estimate for minimum ice volume for 2012 is around 12k, or THREE TIMES the volume of 2011. Add in a bit of the low-memory-of previous-years and that might drop to 8k, or double 2011′s volume. In any case, the odds of setting a new record are abysmally low, unless the OP is completely wrong.
So, being a non-scientist, I’m left with a conundrum. Either the OP is FOS, or we’re likely in for a HUGE increase in sea ice volume for September. Thus, if you’re right, either the OP is garbage or we’re in for some seriously high sigma weather.
I may well look into this when I can make the time. You said: “Probably what is going on is that colder winters create more ice, which takes longer to melt.” Be very cautious with this, in recent Winters mid latitudes were colder than average, but the Arctic was warmer. e.g. GISS Maps. http://data.giss.nasa.gov/gistemp/maps/
Converting PIOMAS daily to monthly wouldn’t be that difficult, it’s just it’s not a case of copy down and copy/paste to deal with the mass of data. Once in excel it’s not a major operation to copy down overlapping 30 day averages for all PIOMAS days (apart from the first 29). Use formula of the form ‘=A1&”\”&B1′ to create an index from PIOMAS Year and Day, i.e. Year in An and day in Bn that formula giving an index of the form 1980\239 (forward slash doesn’t work in vlookup). Then use Vlookup() to grab the relevant averages from the index / volume table.
Vlookup gets a figure in a range that’s a number of columns right of the index. All you need to do is sort out the dates you want to grab. Again you’d use the formula type ‘=A1&”\”&B1′, you’d feed that with 12 instances of the year, and the series 1, 31, 61, 91, etc up to 361 and use the formula to make your 1979 values. Then copy the days you want down by referencing 12 rows up, not fill down but e.g. b14 = b2 – that’s how to copy a repeating series down in excel.
Actually now I put it like this, it wouldn’t take me long. If you really want me to do a spreadsheet, just bother me for it at my blog.
A bit late to the party; however, I wanted to chime in that, IMHO, this is one of the better Posts here.
To actually, characterize the model interdependency or lack there of, certainly helps point out to many readers, the inter-relationships of data as a function of the various model types. To explain that closely coupled models point more towards the median, while loosely coupled models are free to represent great variation is wonderful. It is almost like for the first time we can see the median and up to three sigma of the potentials that can occur at any given time.
Thanks for your interest.
Although temperature in the artic has risen over the decades more than elsewhere, this winter has seen a reversal of that trend, due to extreme cold in the Western part and the Baring Straits.
Another reason why land temperature might have a lagged impact on sea ice is river runoff. It will be interesting to see whether sea ice above Siberia stays around this summer, even though the temperatures there are now comparatively warm. There are some large rivers dumping into the artic from Siberia, and Siberia has been very cold this winter, so the river runoff is less likely to melt the ice.
I have converted the PIOMAS daily data into monthly data, using SAS. If you, or anybody, wants a copy let me know. I could not find an email address on your blog. You might want to put the monthly data there.
As I said in my post 290, the PIOMAS series is odd in that lagged dependnet variables, using differenced data, have positive coefficients. That virtually never happens in a real data series, one with separate observations for each period. I replicated the analysis with monthly data (in #290) with the daily data. The lagged dependent variable has a positive coefficient of .69, t ratio = 76.3. That is, the figure for each day is just a tweaking of the figure for the day before. In that case, an initial modeling error can easily get magnified over time. All those attempts to forecast using this series, therefore, are meaningless.
Going one step further with T. Marvels data, my prediction for this summer’s Arctic sea ice extent will mirror that of 2010. Although slightly off from 2009 in timing, 2011 mirrors 2009 in temperature. The sea ice has mirrored the 2009-2010 winter so far, with a late start to the spring thaw. My prediction is for a similar late minimum (very late Sept.), with sea ice extent reaching a similar minimum to 2010.
That is lower land temperatures are followed by more ice volume several months later.
Congratulations on discovering seasons. You are now approximately as advanced as grass.
The ice volume data series is a bit odd. I use anomalies (e.g.,ice volume less the montly mean for the volume over 1980-2011) and then take differences (substrct the prior period anomaly from the present anomaly).
A remarkably pointless process. (A – avg) – (B – avg) = A – B.
Why are you buggering around calculating anomalies and then throwing them away again? All you’re effectively doing is calculating the difference between time points A and B.
The regressions contain lagged dependent variables. With nearly all variables I’ve ever used, including ice extent and temperatures, the lagged dependent variables have large negative coefficients, since changes one period tend to lead to “movement to the mean” in the next period.
This is so incoherently described as to be meaningless. I think it’s just another way of saying that the volume series has an accelerating downward trend, while the other measures (extent, area) are not easily distinguishable from a linear trend – at least over the (unspecified) period you’re using. This is blindingly obvious from a graph, but there are much better ways of testing and describing it.
Could the Ice models be forced to an “ice free” state at the ides of March, then run backwards to see what the conditions would have to be(IMHO, primarily ocean surface temperature and profile with depth) at the end of the previous September to give this result when run forward?
Dan H. – we’ll see who is right. The daily graph yesterday showed 2012 ice extent dropping below the 1979-2000 average, so maybe you’ll be right. It would be interesting if anybody else cared to make a prediction. How about a contest to see who best guesses the summer ice extent?
I agree that the results of my research are pretty hum-drum (see post 289), but I haven’t seen it stated before, and obvious findings tend to become obvious only after they are pointed out.
About taking differences (current period figures less prior period figures) of anomalies: the anomalies are the value less the monthly mean (i.e., the mean for the particular month over the years, in this case 32 full years), as is the usual practice with climate data (most notably temperature). The two “avg”‘s in your equation are different figures, so A-B on the right hand side is not right.
About lagged dependent variables (which should generally be used in regressions if significant): a simplified regression is x = ax(t-1) + bx(t-2), where x(t-1) and x(t-2) are lagged values of x. When variables are in levels (not differenced) coefficients a and b are positive, since the value in one period is related to that in the prior period. But when the variables are differenced, the a and b are negative, since changes in one direction tend to be counteracted by changes later in the opposite direction (for example, if a short-term factor caused x to increase in time 1 and went away before time 2, then x would drop in time 2, all else equal). As I said almost every variable acts that way. The only exceptions are very regular variables, such as USA population, where a and b tend to be zero.
The fact that ice volume has a large positive coefficient on the lagged dependent variable (with differenced variables) means that something screwy is going on. A change in ice volume one day leads to a change in the same direction in the next day. There is something constantly pushing the variable to move in the same direction, either up or down (although that need not show up in a graph because other factors also affect change). I see no alternative but that the model used for calculating ice volume has a built-in trend mechanism, which may be non-linear. I have no idea what it is. In any event, the ice volume series clearly is not based solely on observations, as is the ice extent series.
The next implication is that those who try to predict ice volume using past ice volume data are largely picking up the artifical trend that is built into the data. As I said, such predictions are meaningless.
> Siberia has been very cold this winter,
> so the river runoff is less likely to melt the ice.
What’s been published correlating summer and winter Siberian temperature with river runoff temperature and the following seasons’ Arctic ice melt? I’ve seen more about air temp. and ocean current temp, but not river temperatures. Looks like ground temperatures don’t change very fast:
“… the coldest Siberian region, and the basin of the Yana River has the lowest temperatures of all, with permafrost reaching 1,493 metres (4,898 ft).”
AMEG’s blog’s quite busy, and the UK Parlaiment is having hearings.
This is new to me; anyone watching this?
“Supplementary written evidence submitted by Professor Peter Wadhams to the Environmental Audit Committee (EAC)
“I am writing in response to information provided recently by Professor Julia Slingo OBE, Chief Scientist, Meteorological Office, firstly in the report ‘Possibility and Impact of Rapid Climate Change in the Arctic’ to the Environmental Audit Committee and subsequently in answering questions from the Committee on Wednesday 14 March 2012. In the responses, the Meteorological Office refers to an earlier presentation to the Committee by myself, made on 21 February 2012.
The following comments are based on the uncorrected transcript of Professor Slingo’s presentation to the EAC, 14 March 2012 session, as at: http://www.publications.parliament.uk/pa/cm201012/cmselect/cmenvaud/uc1739-iv/uc173901.htm
1. Speed of ice loss
In response to questions from the Chair, Prof. Slingo ruled out an ice-free summer by as early as 2015. Furthermore, Prof. Slingo rejected data which shows a decline in Arctic sea ice volume of 75% and also rejected the possibility that further decreases may cause an immediate collapse of ice cover.
The data that Prof. Slingo rejected are part of PIOMAS, which is held in high regard, not only by me, but also by many experts in the field. From my position of somebody who has studied the Arctic for many years and has been actively participating in submarine measurements of the Arctic ice thickness since 1976, it seems extraordinary to me that for Prof. Slingo can effectively rule out these PIOMAS data in her consideration of the evidence for decreasing ice volume, when one considers the vast effort and diligence that has been invested ….”
“Western Siberia Temperature Flip in April
Apr 28, 2010; 10:51 AM ET
A dramatic flip from severe, even record-setting, cold to unusual warmth has happened over that part of western Asia centered upon the west of Siberian Russia….
… the cold broke in March and, in mid-April, unusual warmth blossomed over a vast swath at the heart of Eurasia. In Omsk, this warming culminated on Tuesday in a high of 30.0 C, or 86 F–a hot day even in July. For April as a whole, the mean temperature as of Tuesday rose 5.7 C/10.2 F above normal….”
Seldom do we look at Russian products, on my blog on sea ice I show a remarkably good ice map,
which essentially makes the case for a wide open North Pole this melt. The famous continent to continent multi year ice bridge of 2007 melt season, holding up despite the onslaught, is gone….
What does sea ice this Spring tell us about what to expect this Summer? Hard to say. I correlated April-May sea ice with July-August sea ice, and got a correlation of .69 (p. = .001) (data for 1979-2011). That is, over the long haul there is a close connection, as the ice curves move up and down. But when I correlate changes in sea ice (e.g., spring ice in one year less spring ice in the prior year) there is no correlation. Also, the same for changes over two or three years. That is, one cannot use trends in recent years as a guide for prediction.