This year’s sea ice was unexciting. NOAA goes for “2015 Arctic sea ice fourth lowest on record” which is doubtless true.
Tamino has some helpful plots, so I’ve nicked one. I’m pleased that my 2014 comment “Hopefully that too [i.e., 2012] will look like an outlier in years to come” now looks quite true. From a statistical point of view, Tamino says “changepoint analysis can only confirm one rate change, but a smooth suggests more might be going on”; and I’m sure that’s true from that view. From a physical viewpoint I’m less convinced, and would just take a simple LS fit to the whole (satellite) series. A continued long-term decline is the obvious prediction.
Crandles offers 3 separate bets on the [monthly average extent not area] 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). In the event of anything that clearly throws things out like a VEI6 volcanic eruption bets are voidable.
And the data shows:
year mo data_type region extent area avg 2012 9 Goddard N 3.63 2.15 2013 9 Goddard N 5.35 3.74 2014 9 Goddard N 5.28 3.70 4.75 (2012-14) 2015 9 NRTSI-G N 4.63 3.31 5.08 (2013-15) 2016 2 - X 3.97 - X/3 (2014-16)
(note: 2013 was also 5.35 extent in NRTSI, but 3.48 in area. Which shows what a good idea extent is). So I win (hurrah!) and for extra bonus points, as CR notes by email, sea ice extent has to be implausibly low – less that 2 – in 2016 for him to win; so for a £10 concession for early payment, we’ve settled the last one, too.
I believe (see Sea ice betting report wherein Neven unwisely converted his E50 win in 2012 into double-or-quits for 2013-15, that he now owes me… oh, yes, nothing. Because he won last time, so we’re quits :-).
So what if anything does this mean? Or, in CR’s terms, Were you just lucky or skillful? Most of my thinking (as I said before somewhere, I’m sure) was based on a Impact of instantaneous sea ice removal in a coupled general circulation model by D. Schröder (who did the work) and W. M. Connolley (who did something). Which showed – at least in a model – that the sea ice really isn’t very sensitive to sudden loss; there is no tipping point; if you strip off the ice it recovers quickly, in a few years. To reduce the sea ice you need years of increasing forcing leading to less ice. Which, over the long term, we’ll have I think. But it means I think that 2007 – and then 2012 – were less important than other people thought (see some quotes from 2008). However… it wouldn’t like to over-emphasise that. Who knows what future years will bring?