Aargh! Just as the Arctic sea-ice anomaly was settling down to a reassuring ~1.25Mkm2, after the rapid October recovery from it’s record low level, suddenly it has done another triple back-flip and colliwobble. CT’s current number is -1.759 Mkm2 (here’s the graph).
I was just thinking the other day that we might see a mean decline in Winter Season ice area of something in the region of 10%, when this happens. It’s probably a temporary blip. Perhaps.
In case you don’t realise, the difference between a Winter (October-December by CT’s reckoning) seasonal anomaly of, say. 1.5, rather than 1.25 Mkm2, is really quite substantial. Winter anomalies have generally been slight and slow (though still statistically significant), even as Summer sea-ice records are shattering all around us (2005, 2007). Whilst the absolute amount lost is relatively smaller than in Summer, the rate of decline, if the anomaly this Winter were to be around -1.5 on average, is much faster than previously.
Ray Pierrehumbert reports substantially on the Sea Ice bit of the AGU, including on Mark Serreze’s rather bleak observations about rates of change and the implications for sea level estimates. Perhaps we are seeing another example of the ’state-change’ of conditions which is currently concerning most of the Cryospheric fraternity.
Now, back to that bet… I wonder if Joe is looking like a better bet than he was a week or two back?
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December 13, 2007 at 2:50 am
Aaron Lewis
A few months ago you told me that I was unduly pessimistic about Arctic Sea ice when I suggested that the Arctic could be substantially ice free by the end of 2010 melt season.
Is that still your view?
Many of the guys that I talk to have a legal obligation to design structures that have a 95% confidence of surviving and protecting public safety during a 200 year return event. Regarding Arctic ice, what events have a 5% chance of occuring in a 200 year period?
I take very seriously many risks that have only asmall chance of happening, but which then have significant impact. Where does the heat absorbed by an ice free Arctic Ocean go? What is the nearest heat sink?
December 13, 2007 at 8:46 am
Steve Bloom
Last year at this time the anomaly was very similar. OTOH that turned out to be part of the run-up to summer 2007.
Joe seems to be looking a lot better.
December 13, 2007 at 9:27 am
fergusbrown
You’ll have noticed, Aaron, that I haven’t joined in on the ’sea-ice bet’. This is because I tend towards the view that the Summer level will continue to decline on average, but that we are unlikely to see another year like 2007, in terms of the difference between annual levels. It seems more likely that 2008’s Summer level will be close to 2007’s, either side (but slightly more likely to be higher), and the same will be true for 2009 and 2010, but slightly lower (at least one of these years could break the 2007 record).
That means that I don’t think there will be only 10% of historic mean Summer levels by 2010, or 5% by 2012. My feeling is that the numbers should be closer to 15-20%. Don’t look for clever science on this, though; it is based more on ‘pattern recognition’ in the trends, and a tendency of mine to imagine things changing in a non-linear way. Earlier in the year, I used the term ‘quantum shift’, but this is not quite right; what I was trying to get at was more like ‘regime switch’, on a sub-decadal level.
I do suspect that there will be a further ‘regime shift’ at some point between now and 2020, but don’t think it will occur before 2010.
Personally, I’d like to see some updated information on what is happening with the Beaufort Gyre (direction, vertical mixing, mean temperatures), to help understand the process of change better and the likelihood of continued rapid decline.
Like you, though, I take the associated risks very seriously. Where I think Mark Serreze hit the nail on the head, is in the underlying sense that this year we have passed a point, which wasn’t expected this soon, at which the further decline of the Arctic sea-ice is now inevitable, and its recovery next to impossible. I’d offer quite long odds on Summer sea-ice levels ever coming within 1 million km2 of the historic mean again. (in our lifetimes).
As for the bet, Steve, on the day, it is possible that the difference will come down to one or two percentage points. What may be decisive in this is how the remaining multi-year ice (stuck to the N of Greenland) behaves next year, If some of it is flushed out of the Fram Strait (again), Joe might win his bet.
December 13, 2007 at 9:05 pm
Aaron Lewis
Arctic Sea ice floats on fresh water that floats on seawater. The fresh water insulates the ice from the warmer seawater below. The ice protects the fresh water from storm mixing. Where we have lost the surface fresh water (from storm mixing) or it has thinned, it is less likely for sea ice to survive the melt season. Without that surface freshwater, the Arctic Sea Ice is as tender as “a maid’s heart in the spring.” (Look at the area of Antarctic Sea ice that melts each year!) The other feedback is the less ice, the more moisture in the atmosphere, keeping the Arctic warmer in the winter, thereby reducing ice formation.
Unless you can offer a good source of “cold” to freeze a lot of salt water, or a good source of fresh water (GIS?) to float across the Arctic Ocean, I expect Arctic Sea Ice to continue to decline rapidly. If I accept that the Arctic is in a nonlinear process, and I extrapolate past performance of that process, then I have to expect that this year’s summer melt will be 6 or 7 standard deviations off of the 1979 to 2000 baseline. In your terms, I expect next summer’s ice at less than 50% of the baseline, 2009’s at less than 30%, and the Arctic Sea ice pretty much just gone 2010. Let me say it for you, “That’s impossible!”
The two questions of interest to me are: “What is the heat content of the underlying water”, and “What is the shape of the curve that describes the loss of the freshwater insulating layer? However, these have become moot points. As a practical matter for abatement or mitigation, 2010 and 2012 or even 2015 all equate to NOW!
I think the tipping point for Arctic sea ice was around 2000, and it has taken a few years to see the trend in the data.
December 14, 2007 at 4:57 am
Dano
including on Mark Serreze’s rather bleak observations about rates of change and the implications for sea level estimates.
Hmmm…
Harkening back to grad school ecology: using a sigmoid curve to graph ecosystem change, as we approach the tipping point [somewhere above the inflection point of the curve], the rates of change increase rapidly as a function of the position on the curve.
I’d like to see how our societies and economies function in regimes where we have no knowledge (after a tipping point). After all, we adapt so well to change today [/irony].
Best,
D
December 14, 2007 at 7:20 pm
fergusbrown
Trouble is, Dano, we also don’t really know whether changes to the climate system would follow a sigmoid curve in the same way that ecosystems can. I still sense that too many people are looking at 2007 in too ‘linear’ a way; in this I am probably not too far from William’s pov. There is too much which suggests that this Summer was something of an outlier, rather than the start of a new pattern. If in doubt, follow the longer term yellow brick trend line…
December 14, 2007 at 11:11 pm
Steve Bloom
Fergus, note that Maslowski et al got their results using data through 2004 only; i.e. missing the record period of 2005-7. As Maslowski said, adding in that period might give an even more precipitous outcome. Note also that the NCAR model (second best to Maslowski’s) shows a 2007-like sharp drop, albeit in 2020, so what we saw this year was only unexpected in terms of the timing.
IMHO the most meaningful statistic of all is the 50% reduction in ice volume since 2003, which is much sharper than the area or extent changes.
Regarding Joe’s bet, wasn’t it for 2020? If so I don’t see how what happens to the multi-year ice next year in particular is especially critical to the outcome. BTW, Serreze et al describe a new loss mechanism for the multi-year ice that doesn’t involve flushing into the Atlantic: They observe that the Beaufort gyre, which formerly served to enhance multi-year ice, is now acting to melt it.
I’m not sure I agree with your apparent assumption that there could be anything like a stable condition at the 15%-20% level. The impression I have is that most of the scientists assume a quick collapse through that level down to remnant/fast ice (which presumably would linger for a while), although I have no idea what percentage that would be. If it turns it to be slightly over 10%, I guess Joe could lose on a technicality even if he’s right on the substance. OTOH is it clear that the agreed metric (UIUC area?) will still be meaningful in the 10% range?
Regarding the remnant/fast ice, IIRC it had been assumed that the Canadian archipelago ice would be much more persistent that this summer showed it to be. The opening of the main NWP seems to have been a big surprise notwithstanding what the rest of the ice was doing. I don’t know what the current patterns are on that side of Greenland, but it may be that the northern archipelago ice won’t be long for the world, and if so the long-term persistent remnant/fast ice may be much lower than 10%.
BYW, I’ve noticed some early signs of denialists starting to convince themselves that complete summer loss is consistent with their views. One wonders what it will finally take.
December 15, 2007 at 12:16 am
Steve Bloom
Erratum: Actually the 50% volume loss (from data awaiting publication) is from 2004 (not 2003 as I said above), which makes it entirely subsequent to Maslowski’s data period. Eek.
December 15, 2007 at 12:34 am
fergusbrown
There’s a lot to deal with in your comment, Steve. The first point I’d make is that Maslowski is definitely at the sharp end; his team has an excellent track record, and I wouldn’t want to contradict them. But their projections are still outliers, when compared to the other cryo. specialists. On Maslowski, Serreze is quoted (by the BBC) as saying that he still thinks they are jumping the gun in terms of timing, though at the same time freely admitting that he has had to revise his earlier assessments considerably in the past couple of years. Who does the ‘informed amateur’ go with?
I agree that the volume figures are important and revealing, but we have so little hard data on this, especially historically, that it is hard to put into a climate context comfortably. This is, of course, the problem with the whole of cryosphere research: even the best experts are still working in relatively unknown territory. Because of this, any one of a number of projections or speculations could turn out to be right; it just happens that my speculation is slightly higher than Maslowski’s. But he is the expert, not me.
I thought Joe’s bet was for 2012. I’ll take another look. Hence my use of the timings in the post.
I haven’t made myself clear on that 10-15% figure; that was for 2010-2012. I don’t think there will be a new ’stable state’ at this level (as you point out, that makes no sense), but I do think that, once the level gets down below a certain level, the trend in reductions must slow down, simply for the reasons of fast ice, coastal ice and multi-year ‘pockets’ persisting. You are right that this may be less than 647,000 km2 (10% of the long-term extent average ).
Two questions need answering then; how quickly are we going to reach the condition of no Summer ice except the ‘persistent remnants’, and how big the combined area of these ‘remnants’ will be. I don’t know the answers to these. Who does?
My current suspicion is that Joe might narrowly lose his bet, but there may be a final difference smaller than the error allowed by UIUC’s methodology. OTOH, he might miss his bet by a year or two. There isn’t that much in it, either way.
On the psychology of complete denial, there will always and inevitably be a minority for whom recognition of the blindingly self-evident will remain impossible. Since there is no known cure, the best we can hope for is that their advocates are shown to be the shills and frauds which many of them are, and they become disillusioned with their own pig-headedness.
December 15, 2007 at 1:08 am
fergusbrown
No, you were right; their bet with Joe was for 2020. It was the later bets which were for 2012-13. But I am not sure whether Joe is referring specifically to the Summer minimum being at 10% or the mean annual extent being at 10% (or was it area?). I must do some more reading…
December 15, 2007 at 4:37 am
Steve Bloom
I have the impression that Maslowski was reporting brand-new results. If his critique of the other models is correct (that they aren’t fine-grained enough to allow for measured flow of warmer water into the Arctic Ocean), then the other teams have a great deal of catch-up to do. Note that Serreze’s 2030 figure was to all appearances a hand-wave. One would think that under the circumstances if he had any sort of contradictory results he would have said so. Now it will be interesting to see how long of a wait it is before the next NCAR model results are published.
Note that Maslowski said his model results were validated using thickness data (almost certainly his own set, so I’m not clear to what extent it’s different from the 50% reduction one). I guess we’ll have to wait to see the paper(s) to know the details, but bear in mind that Maslowski has access to data that none of the other modelers have (the stuff outside the “Gore box”). He can’t publish it, but having it available has to be a big help.
The next couple of summers should be interesting.
December 18, 2007 at 8:58 am
Gareth
The next couple of summers should be interesting.
The fine art of understatement.
December 18, 2007 at 10:20 am
fergusbrown
We’re quite…British in our sensibilities here, you know, what…
December 19, 2007 at 5:45 pm
Hank Roberts
Anyone clicking the link in the main post around today’s date:
Caution for links directly into the charts at Cryosphere Today —
“NOTE: The timeseries graphs on this site are currently incorrect. We had a hardware problem corrupt the data and are currently recreating the timeseries from original data sources. Expect the correct data in 5-7 days. We apologize for the inconvenience.”
This happens. It’s one reason why many other sides, like the IPCC, ask people to link to their main or index page instead of to contents within.
December 20, 2007 at 3:16 am
Aaron Lewis
Regarding the bets - How will they account for ice bergs dispersing from GIS (and other land based ice) at an accelerated rate? Most will go south, but some will go north. That will be ice in the water, but it is not “sea ice”.
Northwest passage? Sea ice is one thing, but ice bergs comming off of land may have big rocks embedded in them. Even “Ice-C” hulls have to be careful bumping against rocks.