tag:blogger.com,1999:blog-5337555368793819627.post3690078828662051438..comments2023-06-07T09:04:36.390-04:00Comments on More Grumbine Science: 2011 Sea Ice OutlooksRobert Grumbinehttp://www.blogger.com/profile/10783453972811796911noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-5337555368793819627.post-67672770386015232042011-07-20T11:07:13.902-04:002011-07-20T11:07:13.902-04:003.9 km^2 is much higher than I predicted for 2009,...3.9 km^2 is much higher than I predicted for 2009, but my method then was obviously wrong so I am not going to repeat the same mistake. It was based on the idea that there is a biennial oscillation and that we had passed a tipping point. <br /><br />The idea of a biennial oscillation is obviously wrong, which an inspection of the September ice extents would have made clear. Also clear, is that we have not yet reached the tipping point, but that does not mean that I no longer believe that it exists. Once the September ice extent gets too low for the ice to completely recover by March, then it is bye-bye Arctic sea ice, both summer and winter.<br /><br />My estimate of 3.9 +/-0.1 is not based on what I think will happen. My idea is to place a bet which produce the best return for the least risk. In other words, I expected odds of 10:1 for an estimate so out of line with that of everyone else. I regard as a 50% possibility that this year's minimum will be a record. So even if I did not win this year on average I would make a profit.<br /><br />As you may have gathered, I am not at all confident that my estimate is correct so I have to decline your offer of a 30:1 odds on bet. <br /><br />However, you are an honest man and I am sure you would not like to make an unfair profit, so I'll take your odds and bet 50 quatloos that the ice extent will NOT lie between 4.0 and 3.8 km^2 at 30:1. No new record this year and I win Q1500 :-)<br /><br />Cheers, Alastair.Alastairhttps://www.blogger.com/profile/15152292130415788120noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-6694312795403436512011-07-18T17:13:07.505-04:002011-07-18T17:13:07.505-04:00If I recall correctly, this is a lot higher than y...If I recall correctly, this is a lot higher than you've been suggesting in previous years. Why the change?<br /><br />The midpoint between our guesses is 4.15 million km^2. <br /><br />For you, this is 2.5 sigma above your estimate, given your sigma, so you figure there's less than a 1% chance of reality turning out to be higher than that.<br /><br />For me, it's 0.25 million below my guess, but my confidence (my 1 sigma) is only 0.5 million km^2. So it's only 0.5 sigma below my guess. So I figure there's a 30% chance that September will below 4.15 million km^2.<br /><br />Given our respective degrees of confidence and estimates, you should offer me 30:1 odds (you pay 30 quatloos to my 1) on an over/under bet compared to 4.15 million km^2.<br /><br />So, you up for that? No bet if it's exactly 4.15 reported from NSIDC, but otherwise we go ahead? I'll put up the 50 I won from you last time :-)Robert Grumbinehttps://www.blogger.com/profile/10783453972811796911noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-49628465623807237892011-07-18T16:45:15.289-04:002011-07-18T16:45:15.289-04:00Well my guess is 3.9 km^2. What odds do you give m...Well my guess is 3.9 km^2. What odds do you give me for that +/- 0.1km^2?Alastairhttps://www.blogger.com/profile/15152292130415788120noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-35966947156343799682011-07-18T13:06:29.125-04:002011-07-18T13:06:29.125-04:00Thanks larry. I had looked for your write up, hav...Thanks larry. I had looked for your write up, having read it before, but couldn't find it (or Chris Randles') at Neven's. I'll update the post itselfRobert Grumbinehttps://www.blogger.com/profile/10783453972811796911noreply@blogger.comtag:blogger.com,1999:blog-5337555368793819627.post-31552007632244333422011-07-18T11:55:22.654-04:002011-07-18T11:55:22.654-04:00I might add that the trend for PIOMAS September vo...I might add that the trend for PIOMAS September volume estimates appears more ominous, and also (so far) looks like it could be following a Gompertz curve:<br />http://neven1.typepad.com/.a/6a0133f03a1e37970b014e87616da4970d-pi<br /><br />As a visual reference, both graphs include a horizontal line at some arbitrary low level we might call "virtually ice free" (1m km^2 extent, 2k km^3 volume).L Hamiltonnoreply@blogger.com