Apr 28 2008
Arctic Ocean Ice Free in 2008?
There’s been a buzz going around that maybe the Arctic Ocean will be ice free this summer. Unlike the surface temperature record, the veracity of the sea ice record does not seem to be in dispute on the Internets. The Arctic sea ice is declining.
I’m offering my no-skill prediction of the sea ice extent (as reported at Cryosphere Today). By no-skill, I mean that I have assumed that the linear trend from 1950 through 2007 will continue. This means that since 2007 was such a large negative anomaly, that my prediction is there will be more ice extent this year than last.
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Last year, the sea ice extent for the summer was 12.5 million km2. This year, I predict that there will be 0.7 million km2 (or 5.6%) more ice than last year.
Does anyone else have any quantitative predictions? They don’t have to be scientific; mine weren’t. When the summer numbers come out, there will have to be suitable punishment for the losers.
[Added 29/April/2008]
The above plot shows the spring ice extent. Below is the summer ice extent, and my prediction.
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28 Responses to “Arctic Ocean Ice Free in 2008?”
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There’s a new paper (GRL?) that came to the same conclusion you did based on climatology. Their big assumption seemed to be that last year’s lack of cloudiness wouldn’t repeat. OTOH so far things look pretty clear (and see this interesting site; scroll down for the posts). Wayne’s prediction aside, it seems safe to say that if this year is close to as relatively cloudless as last year there will be a new record since the ice is in the worst shape on record.
I’m dying to see Maslowski’s results, but no paper yet AFAIK. Most of the other sea ice experts seem to have been rendered a bit squirmy by such a short-term prediction.
[Reply: Steve is probably talking about this paper by Deser and Teng: Evolution of Arctic sea ice concentration trends and the role of atmospheric circulation forcing, 1979–2007.
Abstract: The retreat of Arctic sea ice in recent decades is a pre-eminent signal of climate change. What role has the atmospheric circulation played in driving the sea ice decline? To address this question, we document the evolution of Arctic sea ice concentration trends during the period January 1979–April 2007 in light of changing atmospheric circulation conditions, in particular an upward trend in the wintertime Northern Annular Mode during the first half of the record and a downward trend during the second half. The results indicate that concurrent atmospheric circulation trends contribute to forcing winter and summer sea ice concentration trends in many parts of the marginal ice zone during both periods. However, there is also an emerging signal of overall Arctic sea ice decline since 1979 in both winter and summer that is not directly attributable to a trend in the overlying atmospheric circulation.]
Atmoz–
I’m always game for predictions. But could you post the link to the official data metric we are to predict? I’m clicking around and found this:
data for four seasons.
and clicked every link here.
I found a variety of data sets. They all are in qualitative agreement with what you show, but none specifically match what you show.
I plan to enter this contests, and anticipate being just as far off on my prediction for ice extent as my prediction for GMST for 2008.
The plot above shows the spring and now summer ice extent from Cryosphere Today.
That page doesn’t actually look like it’s been updated in a while. Is there some regularly updated source (maybe monthly) somewhere?
Ok… Yes. Now that makes sense. Now I need to think of a basis for making a “prediction” and post. Maybe we can set up a betting scheme and someone can win some quatloos.
[Reply: I don't know what 'quatloos' are, but since I'm going to win, I look forward to finding out.
]
No, it wasn’t Deser and Teng. The one I saw (might have JoC or JGR rather than GRL; unfortunately a quick google didn’t locate it) assumed that cloudiness this year would be the average of 2001 to 2007. As cloudiness is a big factor and 2007 was an exceptionally low year, this led to the unamazing conclusion that 2008 likely would not set a new record. I didn’t read the paper itself and so don’t know exactly what it assumed about ice conditions (presumably low, but I suspect not as low as it has turned out).
IIRC William Connolley is still taking sea ice bets, but he’s going with climatology.
[Reply: Was it Gorodetskaya et al.? That's the only other recent paper I can find that's somewhat related. (I haven't read the whole thing, just the abstract and skimmed the text and figures.)
Climatology is always a good bet.]
It’s a shame that we don’t have Southern Hemisphere data from the same source, or will have ever.
lucia you cant make quatloo bets here. Quatloos are the currency on CA. Here in Atmoz, I suggest the currency should
be “fizbins”
That way I can establish a currency exchange between fizbins
and quatloos and be a money changer.
Its like taking the vig.
Here’s that paper (in GRL last week). Actually it discusses atmospheric forcing rather than just cloudiness. It turns out they did have one outlier result showing a slight reduction from 2007 given the same conditions in 2008. There seemed to be more than the usual quantity of caveats.
Abstract: Ensemble predictions of arctic sea ice in spring and summer 2008 have been carried out using an ice-ocean model. The ensemble is constructed by using atmospheric forcing from 2001 to 2007 and the September 2007 ice and ocean conditions estimated by the model. The prediction results show that the record low ice cover and the unusually warm ocean surface waters in summer 2007 lead to a substantial reduction in ice thickness in 2008. Up to 1.2 m ice thickness reduction is predicted in a large area of the Canada Basin in both spring and summer of 2008, leading to extraordinarily thin ice in summer 2008. There is a 50% chance that both the Northern Sea Route and the Northwest Passage will be nearly ice free in September 2008. It is not likely there will be another precipitous decline in arctic sea ice extent such as seen in 2007, unless a new atmospheric forcing regime, significantly different from the recent past, occurs.
Citation: Zhang, J., M. Steele, R. Lindsay, A. Schweiger, and J. Morison (2008), Ensemble 1-Year predictions of Arctic sea ice for the spring and summer of 2008, Geophys. Res. Lett., 35, L08502, doi:10.1029/2008GL033244.
[Reply: Many thanks for the pointer.]
This related paper (title/abstract pasted below) also appeared last week. I haven’t read it yet, but it looks interesting since it analyzes fresh data from new satellites rather than devoting itself to shoehorning old models into the new reality. NCAR did a press release here.
Also I see that there’s a bit of red meat for the auditors, in case they don’t already know about it. This is an interesting approach. IMHO it won’t really end the sniping, but it will put McI and his cohorts into permanent ignore mode if he’s unable to produce. I thought it was a little odd that the funding came from NOAA.
_______________________
“The contribution of cloud and radiation anomalies to the 2007 Arctic sea ice extent minimum”
“Reduced cloudiness and enhanced downwelling radiation are associated with the unprecedented 2007 Arctic sea ice loss. Over the Western Arctic Ocean, total summertime cloud cover estimated from spaceborne radar and lidar data decreased by 16% from 2006 to 2007. The clearer skies led to downwelling shortwave (longwave) radiative fluxes increases of +32 Wm?2 (?4 Wm?2) from 2006 to 2007. Over three months, simple calculations show that these radiation differences alone could enhance surface ice melt by 0.3 m, or warm the surface ocean by 2.4 K, which enhances basal ice melt. Increased air temperatures and decreased relative humidity associated with an anti-cyclonic atmospheric circulation pattern explain the reduced cloudiness. Longer-term observations show that the 2007 cloudiness is anomalous in the recent past, but is not unprecedented. Thus, in a warmer world with thinner ice, natural summertime circulation and cloud variability is an increasingly important control on sea ice extent minima.”
Atmoz, Lucia, and Steven Mosher, if you want to bet Quatloos I will gladly hold the proceeds until a winner is declared. Moreover, since one of the bettor is also the judge, I will volunteer to judge also.
Steve M, I too could act as the money changer, when needed. Just saving you the trouble.
Of course there is one rule. IUn the event of a tie the proceeds go to the Judge and Money Changer who will define an appropriate charity/foundation. I have on in mind. Steve M, you may list one here also, if you choose to serve.
Darn, I see that bit fiddlin internet Genie has struck again. Otherwise how do those typos get in there?
[...] Atmoz proposed a bet on the summer sea ice extent and placed his best at 7.7 million km^2, using an ordinary least squares (OLS) regression on data from 1950 to last year. This means he is predicting the ice will be well above last years record low of 5.557 million km^2. [...]
Atmoz– I apologize for the endless trackbacks. Wordpress is doing something funky, and the post had serious “issues” (as in not displaying.)
Anyway, I placed my bet.
atmoz, you dont know what QUATLOOS are? did you waste your youth laddie.
http://www.youtube.com/watch?v=7js7RlBAoxI
Here’s my estimate:
6.64324
The entrails have spoken.
SH sea ice extent has shown a strong upward trend over the last 12 months and it will be interesting to see where it peaks in the upcoming SH winter.
We are currently close to a record in anomaly terms for the satellite data era. I predict for the SH winter based on nothing more than trend extrapolation,
A record anomaly of 2.5 million sq kilometers.
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.anom.south.jpg
An absolute record at winter sea ice extent maximum of 16.5 million sq kilometers.
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.365.south.jpg
[Reply: This got placed into the spam bin. Almost like it knew that it was off-topic.]
How do we pick the winner? Do we pick the closest but not over or the reverse of that? Could we do an over under like football? Add spring and summer estimates and pick closest but not over. The bookies in Vegas will bet on anything. If they knew about this there would probably be a book. For example, I heard today there were odds on which NBA athlete would be the next to admit smoking pot!
[Reply: I'd suggest that the closest to the actual value be the winner regardless of whether their prediction was over or under the actual value. This isn't The Price is Right.
]
ARIFS boldly predicts a three-in-five chance of a new record low, although they don’t mention a specific quantity.
I’m in at 6.5
We used to do persistence all the time when we forecast weather, and one of our forecast discussion questions was ‘what was your first guess?’, as usually that was closer to the likely. Why? Analysis paralysis from looking at too much data. Not always, but time pressure in that job gave confounding constraints.
Anyway, looking at these data, there’s an awful lot of new ice out there & I’m on board with the folks above.
I’m in for 6.1.
Interesting to see the effects of a MOC-PDO phase shift on this phenomenon.
Best,
Ð
My guess is 4.5 million km^2, the loss of perennial sea ice this winter has been extensive.
[...] Meanwhile, Colorado researchers say there is a 3 in 5 chance that 2008 will have a new record low. Mr. Atmoz also has a post on [...]
It’s interesting that so far only Phil has dared to go with a new record low. I’ll say 4.49 since a) based on their history, ARIFS is actually pretty conservative and b) for Maslowski’s projection to be correct there would have to be an average reduction in the same range as 2007 in each year through 2013. Just a little more than that this year and I win!
The NSIDC monthly extent for September might be a better metric to use for this, BTW, since they can be relied upon to produce it promptly after 9/30. Also, CT has a history of data problems.
Steve, nice move! NSIDC are having problems with their satellite recently, hence the warning on their web-site.
Phil, that just involves their new daily product. CT has that issue plus others.
Also, I see that over on Lucia’s site some lunatic went for 2.5. That still gives me a win with anything from 3.5 to 4.49, so I’ll stick with what I have.
The point is that there is an important memory effect associated with sea ice. If relatively little is left after the summer, you are skating on thin ice the next year. Thus, a linear extrapolation such as Atmoz has done, makes little sense.
I think the problems the experts have is that they are looking at an arithmatic progression but with all the possitive feedback it is more of a geometric progression. That why each year they are shocked by the melt. What was it, 18 months ago the U.N. panel of over a hundred experts thought it would be the end of the century before there was an ice free arctic?
My guess is five hundred thousand square miles or less. Substancially ice free by the end of summer. I hope, I am wrong! My thought is based on the thin ice not the ice cover. I beleive as it begins to melt, the water will melt it from below as fast as the sun does from above and that the small amount of old ice will flush out on Greenland’s east coast. So you are left with new ice melting on both side (no way it can last).
[...] course, we amateurs were out of the gates long before the experts. Prodded by the indefatigable Atmoz, we placed our bets in April! (I think we can claim “international effort” and [...]