Sea ice again?

At some point I need to decide if I’ll re-start the by-now-traditional sea ice bet for the summer. Before we start arguing over the details, remember that there is a lot of inter-annual variablity so we need to disagree *a lot* to have a meaningful bet. But at least one person has said in the comments that they feel “worried” by this years ice, so that suggests pessimism that I can exploit!

Any thoughts about what you might want to bet about, please leave a comment. My default position is going to be “will fit the 1979-2009 slope extrapolated to 2010”. Bear in mind that this isn’t a forecast – it is some kind of rough idea. If I frecall, RMG thought ~0.5 Msqkm was about the right uncertainty.

Oh, and here is a pointer to http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm to get you started.

19 thoughts on “Sea ice again?”

  1. I’d be willing to bet that the horse race that starts in a few weeks will be interesting right up to mid-September.

    But nothing more …

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  2. So you would be going for just above 5 million sq km or close enough to bang on.

    Record low, must be close to 50% probability. odds?
    Or is 4.5 or 4.75 million square km different enough?

    Funny how the deniers never put there money where their mouth is , unless interpretation is subject to their absolute discretion.

    We could have a side bet on the date of the minimum. I’ll go for September 17.

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  3. The 0.5 million km^2 is the standard deviation about something like that best fit line. (It rounds to that for the 1979-2008 best fit, and I doubt it’s appreciably different for 1979-2009.)

    Your mistake last year was using only 1979-2006 — excluding the wildly deviant 2007 and 2008 years. If you’re going to include them, I might be hard-pressed to come up with a prediction different enough to be interesting. Or not. We’ll see what happens in May, when I get to doing the work on this.

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  4. The ice that’s there and that will continue to form until March is thin, patchy and young and will melt quickly.
    I’d risk short odds on beating the 2007 minimum by a large margin this year.

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  6. Robert Grumbine

    What mistake did WC make last year? As I recall (and I do: I had to pay up!), he got a few bets and won; so what was the mistake?

    [I decided taht 2007/8 were “exceptional”, so based my prediction on the fit to the 1979-2006 data. As it happens, fitting to 1979-2008 would have produced pretty well the exact correct answer. However, that was chance. However, on retrospection, it is clear that my assertion that 2007/8 were exceptional and should be excluded was twaddle and I should have known better -W]

    William

    No bet with me this year I think! By now it’s pretty abundantly clear that 07 was an outlier and not an indicator of a step-change (the hypothesis that triggered this betting).

    I’m guessing you’ll get few takers on any side (but lots of ppl trying to persuade you to bet on things you don’t want to back!). OTOH it looks like Vince Whirlwind might be up for something, so what do I know?

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  8. If the sea ice leaves early that will mean that all that historically covered area of oxygen rich cold water will be exposed to 24 hr sunlight. Will we see an increase in the sea’s productivity of plankton?

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  9. I’d be willing to bet that the horse race that starts in a few weeks will be interesting right up to mid-September.

    I’d take that bet. I’d be willing to bet it will be as dull as ice melting slowly up until mid-September.

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  11. doug: that question’s a little confused; the answer would have to be ‘it depends, yes and no.’

    Plankton is a collective term for floating organisms.

    Look for discussion more generally rather than asking a black-and-white question and you’ll find more results.

    Here for example:
    http://dx.doi.org/10.1016/j.jmarsys.2008.07.007 mentions primary producers (ice algae and phytoplankton) that live in or associated with the sea ice. Other organisms eat that first growth.

    http://scholar.google.com/scholar?hl=en&q=biological+productivity+arctic+sea+ice&as_sdt=2001&as_ylo=2009&as_vis=1

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  12. William should ban you for that comment, dhogaza. The 2nd test between Australia and Pakistan was a cracker – more twists and turns than a Monckton diatribe.

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  13. If you do not want to put up actual money, how about a pool with the prize being a post on your blog? You might have to follow up with a rebuttal blog but hey it could be interesting.

    Yes I know it becomes a lucky dip to a considerable extent and you could end up with a total ignoramus doing a post. (Nature has a way of making fools of us all)

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  14. If everyones’ (or maybe just all sensible people’s) guesses for this year are within error margins then it is a boring lucky dip. So it seems to me that we now need some more skillful test to see who is more skillful. So why not require people to predict more than one year?

    Williams default position of “will fit the 1979-2009 slope extrapolated to 2010” on extent column of
    ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/Sep/N_09_area.txt
    gives a line of 163.4-0.078625*year which gives 5.37, 5.29 and 5.22 for 2010, 2011, and 2012.

    Suppose I suggest a slightly more aggressive line of 206.26-.1*year giving 5.26, 5.16 and 5.06 for those three years. Would seeing who is most accurate after 3 years be less of a lucky dip? (Differences of .11 .13 and .15 add to a mere .39 which is still less than a standard error of 0.5 so it would sound like a long competition in order to decide between William and I). However, maybe there are some more extreme views that can be decided earlier?

    What do you think Vince Whirlwind?

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  15. I don’t think I’ll be betting this year. Another loss, and William would be looking for his name to be on the deeds to the farm… 😉

    Reference: http://nsidc.org/images/arcticseaicenews/20091005_Figure3.png

    Predicting that 2010 will be back on the trend implies (by Mk 1 eyeball) not much change (or a small increase) on 2009. Getting three years of increase on the trot hasn’t happened since 79, so my guess is that 2010 will be below 2009. How far below? No guesses from me until we see some more info on the state of the multi year ice (Kwok’s team at NASA should have something soon-ish), though David Barber’s letter to GRL suggests that all may not be as it seems from space.

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  16. I bet the Earth will get hit by an asteroid, and nobody will much care what the sea ice extent is. What odds will you give me?

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  19. Another 6 weeks should be interesting…it was looking pretty extreme until late June, then the melt dropped off somewhat.

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