Or perhaps part 3. I’ve lost track. Sea ice – and now for something just a tiny bit different refers, as does the earlier This year’s sea ice. Yes, it looks like being part 3.
The above is the IJIS sea ice. Nothing very exciting at the moment (NSIDC have some nice pix. April 2011 was bang-on trend). As you recall, we’re trying to agree a bet or bets. I want to bet on monthly extent and some of the others want daily. After too much equivocation, I’ve decided to stick to my guns: monthly it is, and if you don’t like that, you’ll need to find someone else to bet with. Or, you can apply a handy adjustment. Rob reckons (based on IJIS) that the difference between monthly and daily is 0.17 (see this comment so you can adjust your expectation based on that, if you like.
Here is the pic I’m basing stuff on:
Green line is trend-to-year-using-all-data; so the 2011 point is the first extrapolated, and so on. Blue-dash is the trend, using last-10-years. And purple-dash is the same, but excluding 2007 (on the 2007-was-weird-theory; I’m not actually using that line). Red is the LS/Crandles exponential fit. What I find interesting is that every year since 1997 (except 2001) has been below the long-term trend “prediction” for that year. So I’m coming round to the view that things have changed. That means that for the pocket-money type bets, I don’t mind sticking to my pet theory (green line, so to speak) but for the serious money I’m afraid I’ll shift to the last-10-years theory (blue-dash). Where is the line dividing pocket from serious money? I don’t know, but $100 is P and $10k is S.
So to re-visit some earlier stuff: I said the chance of something beating 2007 and setting a new record low within the next 3 years (including 2011) seems quite good. So I’m not betting on that in response to Neven’s offer. But if I switch to the not-so-safe green line I think that just about fits the error bounds, so I’m now happy to take that on for the proposed E50. I’m basing that on the monthly values, of course. If you want to take up the offer based on daily values, then OK as long as we have a “buffer”: if the daily and monthly disagree about whether there is a record or not, the bet is void. Covering “the next 3 years” ie 2011, 12 and 13.
Another multi-year bet was Peter Ellis who says Allowing myself a reasonably wide fluff margin, like you’re doing, I’m prepared to bet £50 that the September monthly average will go below 2 million some time between now and the end of 2016. Bet voided if there’s one or more Pinatubo-scale eruptions between now and then. That looks OK; accepted.
Crandles offers 3 separate bets on the average of [2012, 2013 and 2014] (to be above/below 4.294, I take the high side), of [2013, 2014 and 2015] (4.119, ditto) and of [2014, 2015 and 2016] (3.94, ditto) for £67 each. That seems reasonable and is accepted.
That leaves me trying to satisfy Rob, which I think will be harder, since he wants to bet Real Money ($10k), so I’m going by the pale-blue-dashed-line. I think we might best off going for a bet on the single year where we disagree most, which (within an interesting timeframe) is probably 2016. So taking the 2016 point and subtracting my cowardly 0.5, I offer above/below 3.1, with me taking the high side. The data I’m using there is NSIDC (I’m fairly sure :-) monthly average extent. Having just checked, the IJIS seems to agree closely, as I’d expect (but I can’t find the monthly averages for that pre-made, so I checked 2007/09, which was within 0.1 of NSIDC). I suggest again that we buffer it: if the 2016 value for NSIDC or IJIS differs enough to affect the result, the bet could be void. To sweeten this not-very-good deal, I also offer Rob (but not me) the option to back out once the 2011 minimum data is in.
I think there are other people who have suggested they believe Maslowski’s “near total ice loss by 2016” stuff, and if you believe that, then I’d hope you’ll be happy with 3.1.
Did I forget anyone?