Sea ice: I'm in Nature again

Eat your hearts out real scientists :-) See here. I think its hung off a trip in the icebreaker that QS got; see his blog I get to say Bets have already been laid on whether this summer's ice loss will be more than last year's. William Connolley, a software engineer who used to model sea-ice changes at the British Antarctic Survey, has taken in roughly â¬300 (US$470) so far in the informal online pool he runs. (He bet 'no'.) Connolley points out that, even if a new record is set, that has little meaning in the long term. "We all recognize the climatological trend is downwards," he says, "but what will happen this year depends on weather and natural variation." As for recent media speculation that the ice at the North Pole will be melted this summer, he notes: "There may or may not be open water in the area by September, but nobody is predicting there will be zero sea ice in the Arctic, or that sea-ice extent might halve compared with last year." The possibility of an ice-free North Pole, he says, is a statistical fluke about a particular geographical point that says little about sea-ice conditions in the basin as a whole.

I made up the e300. I'm still not sure what the total actually is. It depends a bit on the carrot exchange rate.

But enough of me. What does everyone else have to say?

What this all means for long-term sea-ice cover remains to be seen. Most computer models have not managed to predict anything like the massive ice losses observed in the past few years. So some think that their predictions of a slow decline in sea ice over the coming century is a massive under-estimate. Or the other obvious possibility is that the models are actually "right" - last years minimum was a fluke; this years won't match it; multi-year ice will regrow, and we'll be back on the steady curve of decline. But thats not at all a fashionable view. "Over the next five to ten years we are almost certainly going to lose all the sea ice" in summer, climatologist James Hansen, of the Goddard Institute for Space Studies in New York, told politicians in Washington DC last month. I think thats b*ll*cks. If Hansens up for it, I'm happy to bet that the ice extent will be at least 10% of what was there in, say, 2007 all the way to 2013. And I'll give him even odds, which is a bargain is he thinks his side is "almost certain".

BTW, the pool on next years ice hasn't started but I expect to run one; there seems to be enough interest.

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I think you're being a little unfair to Hansen, as he's just endorsing Maslowski's results. Speaking of which, the latter has yet to publish, but have any details made the rounds?

[I disagree. If Nature have quoted Hansen correctly, he has said what he has said; he didn't say "according to M..." or "if M is correct, then..." he said 5-10 years. So he now owns those words -W]

By Steve Bloom (not verified) on 18 Jul 2008 #permalink

Off-topic, William, but this

http://en.wikipedia.org/wiki/Image:GISP2_ice_core_eng.svg

is rather misleading. I've gone over Alley's work on the NOAA Paleoclimatology website, just from 10,428 ybp to 100 ybp, rather thoroughly. Recent temperatures, while low, are not lower than the 8.2 kybp event (Bond 5). The total anomaly over the studied timespan is about 3.2 K; this graphic doesn't show that well either.

[Well, you should comment there -W]

By David B. Benson (not verified) on 18 Jul 2008 #permalink

Just to nitpick, He is likely saying it will disappear in 5 to 10 years, so your bet should be by 2018.

[He says its nearly certain by 5-10 years. What does that mean though? Its very hard to parse. If he means "nearly certain by 10, but not at all certain by 5" then why not say "nearly certain by 10"? -W]

>"[He says its nearly certain by 5-10 years. What does that mean though? Its very hard to parse. If he means "nearly certain by 10, but not at all certain by 5" then why not say "nearly certain by 10"? -W]"

You can also equally argue why not say "nearly certain by 5" but he didn't say either so surely this implies some uncertainty between 5 and 10. So if you are proposing a bet why not give him at least just over the average ie 2016?

The bet you have offered seems substantially worse than the bet with Joe Romm. Does that mean you are accepting that you are likely to lose that one?

[Nope, I'd already forgotten about that. I'm offering this bet (without any great expectation that it will ever come to his notice) to try to clarify what he means, and demonstrate that I don't believe it. I don't suppose you'd want to take up his side; or, to put it another way, that you don't believe him? -W]

Imagining an arctic with only 10% of the 2007 extent, I think one could very well say "all" the ice had gone.
Hansen's quote seems extreme to me, but your response is a bit silly. If you really wanted to challenge it with a bet, you should pick a number and a date which are still well below the long-term trend but not as low or as soon as "0.45 Mkm^2, 2013". How about "extent will remain continuously above 1 Mkm^2 from now until 2018" ?

[OK, so you don't think Hansens no-ice is plausible either. I think thats my point. 2018 is a while away -W]

By Nick Barnes (not verified) on 19 Jul 2008 #permalink

Imagining an arctic with only 10% of the 2007 extent, I think one could very well say "all" the ice had gone.

Rubbish. "All" means all. Hansen is unambiguously alarmist, as usual. But then why would we expect any different? After all, his fame, like Gore's, is critically dependent on getting himself in the media as much as possible with doomsday scenarios.

Rubbish. "All" means all.

If you say so. Say, does it flicker back momentarily into "not all" when someone dumps the remains of their Slurpee in Tuktoyaktuk?

Or more to the point, when glaciers on Greenland and Ellesmere Island dump into the Arctic, which marine glacier do all the time.

By Phil Hays (not verified) on 19 Jul 2008 #permalink

Say, does it flicker back momentarily into "not all" when someone dumps the remains of their Slurpee in Tuktoyaktuk?

Dunno. Ask Hansen. His claims are fully deserving of such a worthy response.

2018 is a while away

Yes. Ten years.
The difference between us here is that I am inclined to view Hansen generously - and suggest a bet on the least pessimistic position in his range - whereas you are inclined to view him ungenerously, suggesting a bet on the most pessimistic position in his range. That's all. In fact, his statement ("almost certain ... all ... 5-10 years") is very informal, not at all concrete, and a terrible basis for any sort of bet. It would be interesting to establish an actual bet with him (or with Serreze, say), as a means of finding out his actual beliefs on the subject.
Of course, people do also bet on things which they don't believe will come to pass. But at least it's something, not an empty posture.

[I think we're close to agreement here. We both think that a hard version of his statement is very improbable; that his statement is vague and if he were forced to bet on it, it would be clarified and that would be good. I also don't believe the 10-year version, but I'm not interested in trying to make it into a bet -W]

By Nick Barnes (not verified) on 20 Jul 2008 #permalink

"I also don't believe the 10-year version, but I'm not interested in trying to make it into a bet"

Some might thank that you *say* you don't believe it, but as you don't want to bet, you actually *do* believe it. ;)

"Some might think that you *say* you don't believe it, but as you don't want to bet, you actually *do* believe it."

2018 is pretty close to the bet William has with Joe Romm, so he's got that covered.

I think "certain in 5-10 years" means Hansen hasn't decided whether it's 5 years, 10 years, or in between, and a bet concentrates the mind.

And I hope Mugwump can forgive us mortals for saying "all" when we meant "practically all".

I personally interpret 'over the next 5 to 10 years we are almost certainly..' to mean almost certainly less than 10 years, and probably more than 5 years.

>"I think we're close to agreement here."

Well it seems to me that there are several people commenting and all of the opinion that you should have allowed more time in the bet. So we ought to be close to agreement - all it would take is for you to admit that allowing more time in the bet would have expressed your opinion better and more starkly shown the difference.

So why not admit this - or is this just a tactic to get more posts on your blog?

[All right, *we're* not in agreement then. One more time: we all agree that Hansens claim of no ice within 5 years is trash. No-one is prepared to bet on it, at any odds. No ice within 10 years is more interesting, though I still think its trash. No-one so far has offered to bet on it -W]

William, you say:

Or the other obvious possibility is that the models are actually "right" - last years minimum was a fluke; this years won't match it; multi-year ice will regrow, and we'll be back on the steady curve of decline. But thats not at all a fashionable view.

You state the vague flame of hope I'm clinging to. :)
But I think that's driven more by desire (on my part) than evidence that I can see.

Nghiem finds a reduction of 1 million km^2 from March 2007 to March 2008 that's on a March 2007 baseline of 2.6 million km^2. i.e. ~1.6 million km^2 in 3/2008 down from 4 million km^2 in 3/2002 (~5.6 in the '60s by drift-age model).

At present (from Cryosphere Today's regional area maps), without the weather of last year the lag behind last year's area is almost all due to the East Siberian and Laptev Seas*. While Beaufort, Chucki and Central Arctic (also the Atlantic regions) are at or below last year. (*see figure 4 of NSIDC Sea Ice News 17 July 2008)

By CobblyWorlds (not verified) on 21 Jul 2008 #permalink

No-one is prepared to bet on it, at any odds

I'll take a bet on, say, 0.5 Mkm^2 by 2013, if the odds are right (maybe 10:1 against?). Not at evens, though.

By Nick Barnes (not verified) on 21 Jul 2008 #permalink

Judging from the few times I've heard Hansen speak, he is a mediocre communicator. As you said, his statement is hard to parse. I think it caused you to misinterpret what he meant, which is why I originally mentioned it.

What I would be interested in knowing is what you think is the range of reasonable predictions for the sea ice. What do you think the probablitity of the trend rapidly accelerating? When would you put the 50% likely hood of say < 0.5 Mkm^2? Or what ever other metric you feel comfortable with.

[Hmmm, thats a reasonable question. I think there is a wide range of possibilities, and its hard to rule anything out. I don't think a rapidly accelerating trend is likely; I'll have to have a look at the numbers and draw some lines. There may be some scope for some more interesting bets over the years ahead -W]

Hey, William, could you
(or perhaps this will tempt Atmoz)
take a "significance of short term trends" look at the Arctic sea ice data, along the lines of the ones you two did on annual trends for temperature?

It's obviously a different underlying pattern, up and down annually.

Everyone's watching the pictures day to day for the Arctic -- at their screen resolutions, I'm sure -- and every day there's another pixel or two added to take into account (wry grin). RC has just been through the confusion people manage by getting information out of looking at pictures instead of underlying data.

Is it possible to show how many days it takes to say a trend is meaningful on the sea ice annual chart, knowing the annual cycle and asking if there's a change both day to day and vs. the previous longterm record?

http://nsidc.org/data/seaice_index/images/daily_images/N_timeseries.png

[I'm not in a position to do stuff with the data nowadays; you'll need to try Atmoz. BTW, the japanese site pic is better than the nsidc one, though I can't remember what it is just now -W]

By Hank Roberts (not verified) on 23 Aug 2008 #permalink