tag:blogger.com,1999:blog-5337555368793819627.post5622187559460593625..comments2023-06-07T09:04:36.390-04:00Comments on More Grumbine Science: Sea Ice OddsRobert Grumbinehttp://www.blogger.com/profile/10783453972811796911noreply@blogger.comBlogger11125tag:blogger.com,1999:blog-5337555368793819627.post-43540356877325118682009-06-13T22:16:38.849-04:002009-06-13T22:16:38.849-04:00Eli:
You're fairly close to the professional c...Eli:<br />You're fairly close to the professional consensus in this. A major supporting element is the near-obliteration of thick ice in the Arctic in the late 1990s-present. Had it not been preconditioned that way, the 'perfect storm' of weather conditions in 2007 could not have clobbered so much area. Ignatius Rigor of the International Arctic Buoy Program gave a nice presentation on this at the recent Arctic conference hosted by the National Ice Center and the Arctic Research Commission. Jim Overland also favored the sentiment (Jim, with Hajo Eicken, coordinates the ARCUS prediction pool, among other things). <br /><br />I'm taking a different view almost strictly because most people are taking the view that 2007 represented a step change in the system. If most thinking is in one direction, I'll look for a different direction. Mine shortens to "Ice is taking a sigmoidal approach to ice-free conditions." This still leaves 2007 (and 2008) as fairly drastic outliers, meaning it could be a substantially incorrect view. The data will show within a few years.<br /><br />William:<br />Ok, you're taking an even more different from the consensus view than I am. I'll work up what your model predicts and put it in part of a free-standing post for our bet. Whatever your prediction method comes up with, I'll make an even quatloos bet than September 2009 (as computed at NSIDC) extent is below the midpoint between my prediction and yours. We both go away chucking at what a lopsided bet the other accepted :-) But make it 50 quatloos.<br /><br />Alastair: Ok, my 50 to your 1. I'll take that the September monthly average extent as computed by the NSIDC is over 4 million km^2. And by all means, feel free to contribute to my education. If it's book form, though, be forewarned that I have about 300 on my 'to read' bookcases.<br /><br />I'll stand by the prediction. Observing that the extent loss picked up a few days later doesn't change the basis of my prediction. I figure I should stick with it for at least 1 season before abandoning it. I do link to the NSIDC, and see their figure or William Chapman's, on pretty regular basis.<br /><br /><br />Gareth: Jim Overland said earlier this week that he's expecting the ARCUS forecasts to be up in a couple of weeks. It takes time to bring the disparate submissions in to some vaguely consistent form.<br /><br />In general: If Alastair is right, I take my winnings from the bet with William, and pay Alastair. Now I'm covered! :-) But it's still only quatloos.Robert Grumbinehttps://www.blogger.com/profile/10783453972811796911noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-12555451310650855952009-06-12T06:25:45.940-04:002009-06-12T06:25:45.940-04:00William an I have a principle disagreement. I thi...William an I have a principle disagreement. I think that 2007 was not an outlier, but a step change, mostly because sea ice has hysteresis since one year ice is much easier to melt than multiyear ice.<br /><br />2007 was an abnormally warm year in the Arctic coupled with a perfect circulation storm. Absent another such, or an abnormally cold SERIES of years to regrow old ice and given the pressure of a gradually warming climate, I anticipate that the average minimum ice cover will resume its slow decline, but from a lower base. FWiWEliRabetthttps://www.blogger.com/profile/07957002964638398767noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-30955533120222976632009-06-05T07:08:01.005-04:002009-06-05T07:08:01.005-04:00FYI, on http://solarcycle24com.proboards.com/index...FYI, on http://solarcycle24com.proboards.com/index.cgi?board=globalwarming&action=display&thread=346&page=1 there's a poll of the same, like the ice would take a note. You might have some luck someone taking the bet there.jyyhhttp://erimaassa.blogspot.comnoreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-91021469420052335902009-06-04T00:42:20.806-04:002009-06-04T00:42:20.806-04:00My bet with William is for a new record (we were b...My bet with William is for a new record (we were betting on CT numbers IIRC), so I guess I'm on the warm side of your estimate.<br /><br />When will the ARCUS forecasts show up? Nothing at the web site yet... Presumably that's when we learn the nitty-gritty of your method ;-)Garethhttps://www.blogger.com/profile/01344889228458095563noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-88554397354044071142009-06-03T11:42:17.239-04:002009-06-03T11:42:17.239-04:00Bob,
I have just re-read your post and have to adm...Bob,<br />I have just re-read your post and have to admit, as you feared, I am thoroughly confused :-(<br /><br />But forget that. <br /><br />Not having managed to get you to raise your odds I'll bet one quatloo that the average for the month of September will be less than 4 million sq. km. If it is less than 4 you pay me 50 quatloos, which I will donate to the charity of my choice, viz. The Robert Grumbine Education Trust, to be spent on the purchase of a copy of "The Black Swan" by Nassim Taleb, friend and colleague of Benoit Mandelbrot :-)<br /><br />I did not mention earlier that there is yet another graph of ice extent that is not mentioned directly in your Science links <a href="http://nsidc.org/data/seaice_index/images/daily_images/N_timeseries.png" rel="nofollow">here</a>. I deliberately did not mention it fearing that after you had seen it you might have offered lower odds. Do you want to change your odds now?<br /><br />William,<br />We already have a bet where you offered 2:1 that this year would not be a record minimum. I've put £100 on <a href="http://scienceblogs.com/stoat/2009/03/sea_ice_briefly.php" rel="nofollow">it</a>.<br /><br />Of course I would love to put another £100 (which I can afford) at 50:1 that it will be below 4 M sq km at some time this year, but can you afford to pay out? I'll put 10P at those odds. My £5 winnings will pay for a celebratory beer when I collect the £200 for my other bet :-)Alastairhttps://www.blogger.com/profile/15152292130415788120noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-85239450486075126072009-06-02T17:11:29.520-04:002009-06-02T17:11:29.520-04:00"It's a fair bet -- meaning that I'm willing to ta..."It's a fair bet -- meaning that I'm willing to take either side" - yes that is what I meant. It is a fair bet so not very interesting to you. The game is to find a bet that you think is unfair, but someone else thinks is fair.<br /><br />My own pet theory is that 2007/8 were outliers and that we expect recovery to the long term trend. But I haven't worked out the statistics of what that makes me expect. More ice than you expect, I suspect. Oh go on - you've got all the data and stats packages to hand - suppose I expect 2009 to be on the 1979-2006 trend line, what is my prediction and SD?William M. Connolleyhttps://www.blogger.com/profile/05836299130680534926noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-41205281509783867762009-06-02T14:35:57.592-04:002009-06-02T14:35:57.592-04:00Belette:
It's a fair bet -- meaning that I'm willi...Belette:<br />It's a fair bet -- meaning that I'm willing to take either side. 1:1 for over versus under 4.92 million km^2. I'd also take either side of a quatloo bet based on the standard deviation, so, what 19:1 that the extent will average within 1.645 * .47 million km^2 of the 4.92 (or 1:19 that it won't). (I forget whether 1.645 is the range for 95%, but we can look up that number.) Fair bet, so if you want the inside of the range, I'll take the outside. I do aim, though, at things which can be evaluated with the results this year. If, say, I were wrong about the standard deviation, it'd take quite a few years to establish that (especially since I don't think the mean is stationary).<br /><br />On the other hand, haven't you been taking that even linear might be too agressive a curve? In that case, I'd want better odds from you :-)<br /><br />Yes, that's what I'm referring to on ARCUS.Robert Grumbinehttps://www.blogger.com/profile/10783453972811796911noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-23740619901886178872009-05-31T17:44:16.671-04:002009-05-31T17:44:16.671-04:00*I*'ll offer you real money for your under 4 milli...*I*'ll offer you real money for your under 4 million. Though I agree with PD that monthly averages are a better thing to look at, and quite probably extent too.<br /><br />Bob: is this for http://siempre.arcus.org/4DACTION/wi_ai_getArcticInfo/4161 ?<br /><br />"Given my prediction, one obvious bet is even money that the September average will be less than (or more than) the number I gave, 4.92 million km^2" - isn't this rather an odd bet? You wouldn't care which side you took, since either side has (in your view) a 50% chance of winning. Isn't the obvious bet for you that the sept ice will be 4.92 +/- 1 SD?William M. Connolleyhttps://www.blogger.com/profile/05836299130680534926noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-69921217396106324512009-05-30T03:50:54.174-04:002009-05-30T03:50:54.174-04:00Yes, an extra 0 slipped in there, possible since t...Yes, an extra 0 slipped in there, possible since the current value of 11,500,000 sq km is in that order.<br /><br />I'll take you bet, of 50:1 that it will reach less than 4 M sq km at some time this year. Or are these odds that you giving me for it being below 4 M sq km for a complete calendar month? I wouldn't rule that out for September, but I would like better odds than 50:1. <br /><br />There is a good chance that it will not get down to 4 M until early September, but stay there through early October.Alastairhttps://www.blogger.com/profile/15152292130415788120noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-17742942047552292482009-05-29T20:46:17.762-04:002009-05-29T20:46:17.762-04:00Considering that the global cover has not been as ...Considering that the global cover has not been as high as 40 million km^2 in recorded history, I can't see a bet. If you want to take the position that it'll be greater than 40 million km^2 for a monthly average for some (any) month in calendar 2009, I'll put 1000 quatloos against your 1 that you're wrong.<br /><br />I thought, though, that you'd be offering a bet on being below 4 million. I don't think it'll be below 4. If you want to take the under' side of that, I'll put my 50 quatloos to your 1 that it'll be over 4. (If you run the numbers, you'll see that I'm hedging either bet in my favor.)Robert Grumbinehttps://www.blogger.com/profile/10783453972811796911noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-88182818333709000652009-05-29T17:27:04.006-04:002009-05-29T17:27:04.006-04:00There is a Japanese site here from which you can d...There is a Japanese site <A HREF="http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm" REL="nofollow">here</A> from which you can download the daily data for the last few years. The data is updated twice a day but only the final value is saved.<br /><br />What odds would you give me on the ice dropping below 40,000,000 km^2 this year?Alastairhttps://www.blogger.com/profile/15152292130415788120noreply@blogger.com