Hows the ice?

Posted by William M. Connolley on February 4, 2008
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Gareth inquires if bets are still available for 2008. The answer is yes (although I reserve the right to remove them at a moments notice when things turn against me). At the moment, NH ice seems to be back to “normal”, ie about 1Mkm2 down on the long-term mean; see Le blog de ICE for a current pic from CT. Based on that, I can’t see any reason to expect a record in 2008. Disagree? Then out with your wallet :-). Interesting to note that Antarctica is still high.

Perhaps I should add that I’m not ruling out the possibility of a record min in 2008, nor am I predicting lots of ice. I’m just saying that on 50-50 odds I prefer the no-record side, based on past statistics.

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Comments

  1. #1 crandles
    2008/02/04

    I am expecting the January average ice area to be higher than the last 6 years (possibly 8) but I don’t think you will offer odds of 6-1 if that is shown to be true. ;o)

    Is there any data on ice thickness for this winter? I wouldn’t want to bet against someone with better data.

    [I don't have any such data, so you're safe there -W]

    If the odds were even when the ice area was much lower than previously and the ice area is now higher, isn’t a slight change in odds in order?

    [Maybe not, you always expect it to recover in the winter quite a bit. Odds other than 50-50 are hard to judge. If I offered better odds do you think I could pull in more money -W]

  2. #2 Janne Sinkkonen
    2008/02/04

    If your bets are 50-50, your expect quite a melting next summer, in the sense of expected value of your distribution. Or if your expectation is low, then you have a very long tail towards melting.

    No, I’m not putting in any money. :)

  3. #3 Gareth
    2008/02/04

    Two more items for the form guide, the first courtesy of the Damocles newsletter:

    - a report from the CanWest news service on conditions in the Beaufort Sea…

    There is now so little thick, multi-year ice left, that it is being blown around the Beaufort “like Styrofoam in a bathtub,” says Barber. As the thick older ice moves it pulls away from the thin new ice creating fractures and large areas of open water. [...] Given the way the winter is shaping up, Barber expects to see “another big loss” of ice next summer.
    If the trend continues, he and other scientists predict the Arctic could be ice free in the summer months by 2020, plus or minus 10 years. That means Arctic summer ice, which has capped the planet for more than a million years, might be gone by 2010, says Barber.
    The pace of change is “remarkable, absolutely remarkable,” he says. “I’ve been working in the Arctic for 25 years and in the last five years things have been changing so dramatically that my head is just spinning.”

    The second is a translation* of a Danish web site (linked in my last comment? – can’t remember), which includes some sat info on extent of multi year ice. The Quickscat gif is animated, but only plays once in Safari…

    I think the odds are shifting in favour of my side of the bet, but I don’t have much in the way of British cash. I’ll have a rummage…

    * No idea how the male nurse got in there…

    [Direct Barber this was and see if he's interested in a bet :-) -W]

  4. #4 bigTom
    2008/02/04

    Given the healthy appearance of snow cover (as seen on the ncar/air force snow/ice cover map), I’m betting that 08 will be colder than the recent trend, simply because of a bit more snow/ice reflectivity forcing. It is probably just the luck of the way this years jet stream hit, so I’m not gonna jump onto the GW has stopped bandwagon.

  5. #5 Eli Rabett
    2008/02/04

    FWIW, the easiest time to reach a new extreme is from an old one, esp for something that has a memory, like ice (old/new)

    [You might well have thought so, but past statistics dont bear this out -W]

  6. #6 Gareth
    2008/02/05

    [Direct Barber this wa(y) and see if he's interested in a bet :-) -W]

    I emailed him, and he replied thusly:
    As you know these sorts of things are very hard to predict. That said I will go with a slight increase or near the same as 2007; reason is that we are under the influence of La Nina in NA this winter.
    The odds shift back a little… ;-)
    Perhaps you could ask him to underwrite your losses?

    [Hmm, that looks like a "no bet" to be, very sensible of him -W]

  7. #7 crandles
    2008/02/05

    >[You might well have thought so, but past statistics dont bear this out -W]

    If you are allowed to challenge what people think then why shouldn’t I?

    >[Maybe not, you always expect it to recover in the winter quite a bit.

    What exactly is meant by that? Let me see if I can figure it out:

    http://www.boincforum.info/boincuser/Crandles/IceExtentChangesGraph.PNG

    If I use a straight line fit for the amount of freezing the sum of the errors squared is 5. If I try to improve that prediction assuming greater recovery when the Sept ice is below the average of 6 nearest available years then yes I can get a better prediction. (I used 6 year average as I had mentioned higher than last 6 years earlier.) The sum of the errors squared is reduced to a minimum of 2.7 if I use straight line est – 0.7*amount above the 6yr average.

    So there is something to the ‘expect recovery in Winter’. However, note that it is 0.7*amount below average not a factor of more than one. Consequently, I don’t think your “Maybe not, …” works. There is an expected recovery but only to the extent of about 70% of the anomaly. We have seen a greater recovery than this expected recovery.

    Of course perhaps you are just saying the odds would only change if it changes the amount of money it brings in. My answer to that is it depends how much you are willing to change the odds. 20:19 instead of evens isn’t likely to make much difference. 3:2 and I might be tempted to put a bit on just for fun and with 2:1 I might want to put on a little more than a fun amount. I doubt you are going to offer such odds – I was just trying to provoke you to see if this provided any indication of whether you were feeling more or less confident.

    A table of my figures follows but will probably look awful (feel free to delete it if it is too bad):

    Straight line Sum of Above 6 Straight line est Sum of
    Mar Sept Melting Freezing est of freezing errors^2 year avg -1% above avg errors^2

    1979 16.44 7.2 9.24 8.93 8.501640212 0.183492108 -0.206666667 8.646306878 0.080481787
    1980 16.13 7.85 8.28 7.76 8.518551079 0.575399739 0.488333333 8.176717745 0.173653679
    1981 15.61 7.25 8.36 8.9 8.535461945 0.132887993 -0.06 8.577461945 0.104030797
    1982 16.15 7.45 8.7 8.65 8.552372812 0.009531068 0.101666667 8.481206146 0.028491365
    1983 16.1 7.52 8.58 8.1 8.569283679 0.220227172 0.165 8.453783679 0.125162892
    1984 15.62 7.17 8.45 8.89 8.586194546 0.092297754 -0.105 8.659694546 0.053040602
    1985 16.06 6.93 9.13 9.15 8.603105413 0.299093689 -0.19 8.736105413 0.171308729
    1986 16.08 7.54 8.54 8.41 8.62001628 0.044106838 0.483333333 8.281682947 0.016465266
    1987 15.95 7.48 8.47 8.65 8.636927147 0.000170899 0.421666667 8.34176048 0.095011602
    1988 16.13 7.49 8.64 8.03 8.653838014 0.389173868 0.595 8.237338014 0.042989052
    1989 15.52 7.04 8.48 8.84 8.670748881 0.028645941 0.196666667 8.533082214 0.094198527
    1990 15.88 6.24 9.64 9.26 8.687659748 0.327573364 -0.451666667 9.003826414 0.065624906
    1991 15.5 6.55 8.95 8.92 8.704570615 0.04640982 -0.415 8.995070615 0.005635597
    1992 15.47 7.55 7.92 8.33 8.721481481 0.15325775 0.553333333 8.334148148 1.72071E-05
    1993 15.88 6.5 9.38 9.08 8.738392348 0.116695788 -0.331666667 8.970559015 0.011977329
    1994 15.58 7.18 8.4 8.14 8.755303215 0.378598047 0.391666667 8.481136549 0.116374145
    1995 15.32 6.13 9.19 8.99 8.772214082 0.047430706 -0.515 9.132714082 0.020367309
    1996 15.12 7.88 7.24 7.7 8.789124949 1.186193155 1.131666667 7.996958282 0.088184222
    1997 15.58 6.74 8.84 8.92 8.806035816 0.012987835 0.311666667 8.587869149 0.110310902
    1998 15.66 6.56 9.1 8.84 8.822946683 0.000290816 0.23 8.661946683 0.031702984
    1999 15.4 6.24 9.16 9.03 8.83985755 0.036154151 -0.005 8.84335755 0.034835404
    2000 15.27 6.32 8.95 9.29 8.856768417 0.187689605 0.186666667 8.72610175 0.317981236
    2001 15.61 6.75 8.86 8.69 8.873679284 0.033738079 0.688333333 8.39184595 0.088895837
    2002 15.44 5.96 9.48 9.53 8.890590151 0.408844956 0.31 8.673590151 0.73343783
    2003 15.49 6.15 9.34 8.9 8.907501018 5.62653E-05 0.372 8.647101018 0.063957895
    2004 15.05 6.05 9 8.69 8.924411884 0.054948932 0.4 8.644411884 0.002078276
    2005 14.74 5.57 9.17 8.86 8.941322751 0.00661339 -0.08 8.997322751 0.018857538
    2006 14.43 5.89 8.54 8.77 8.958233618 0.035431895 0.24 8.790233618 0.000409399
    2007 14.66 4.28 10.38
    Total 437.21 191.18 246.03 244.25 244.4382336 5.007941622 4.907 241.0033336 2.695482316

  8. #8 crandles
    2008/02/05

    I was wrong about average Jan area more than last 6 years. It is only more than last 3 years.

  9. #9 Luboš Motl
    2008/02/06

    The current North sea ice anomaly is -0.55, not -1 million sq. km.

    http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.anom.jpg

    See more graphs

    http://arctic.atmos.uiuc.edu/cryosphere/

    [True enough, pointwise. I was taking a rough 3-month average from http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.365.jpg -W]

  10. #10 Steve Bloom
    2008/02/06

    Those two graphs are not completely consistent. NSIDC avoids both daily graphs and the area metric, and this together with other past CT troubles is perhaps an indication that they’re right. OTOH a horse race is no fun at all if you can only watch the horsies once a month.

    On the new record issue, both Eli and William are right. The trick is that absent a truly cataclysmic trend (i.e. enough to consistently overcome natural variability) you can’t expect the next record to happen the very next year, as witnessed by the Arctic sea ice in 2005 (carrot), 2006 (no carrot) and 2007 (carrot).

  11. #11 WhiteBeard
    2008/02/07

    -37 last night in interior Alaska. -36 at Chicken which was the last place recording -40 in Alaska, when they got down to that the first night of this century. Perhaps Corbyn got his continent sighs wrong? :O

    I’m with bigtom as November was more than +5 in Anchorage and that persisted till nearly Christmas. 2008 has been more like I recall my long ago days as a pup, a bit nippy.

    Hudson and Baffin Bays seemed to show earlier Ice than in the few recent years where I made spot checks. Ice growth in the Labrador Sea has continued apace. The wind does blow in the southern Bearing Sea, so coverage oscillates. During the last 4 or so weeks I’ve noticed ice growth extending from Siberia into the Sea of Okhotsk. Sure hasn’t been much Baltic Ice.

  12. #12 P. Lewis
    2008/02/07

    What odds on the NH sea ice minimum for 2008 being the same as 2007?

    What constitutes equal anyway, i.e. what is the error in the obs?

    For example, in the absence of error bars on the individual years or the anomaly baseline, then just by eyeballing the NSIDC data at CT I’m inclined to think there is no reasonable difference between the 2005/06 and 2006/07 winter maximums nor the 2005 and 2006 summer minimums. In fact, except for last year and maybe 1 or 2 others in the last 10 years, was there a statistically significant difference in those minima? (I’ve had a sort of gander through the documentation at CT, but perhaps I’ve just missed this info.)

    Or is this something to e-mail WC @ CT about?

    [Exact inequality is unlikely. In the case of a tie, the bank wins. Thats me :-). No, I doubt I can get away with that, so in the case of a tie, the bet is null -W]

  13. #13 Adam
    2008/02/07

    How much effect on the the creation of early ice would the previous large melt have? That is, assuming that the melt introduces more fresh(er) water into the sea at that point (esp. at the surface?), does this make it easier for ice to form again?

    The two most obvious problems with that that I can see would be if the ice melt didn’t really introduce any/much freshening of the water, and if the temperature effects far outweigh the salinity values.

    [If the fresh water hangs around on the sfc, it makes refreezing easier. And leads to less brine rejection and so perhaps less deep convection, which would also be a warming. Err -W]

  14. #14 Adam
    2008/02/08

    Would those two processes operate on different time scales?

    It’s mere curiosity, but I’m just wondering here whether there is an aid to the rapid recovery of sea ice after a big loss – over and above the fact that the regions gets plunged into darkness for six months (which I realise will help), and how transient or not that might be. The more melt there is, the more “fresh” water there is – though it might never be enough to be factor, obviously.

  15. #15 Adam
    2008/02/18

    I would say “great minds etc”, but I’m not sure MT deserves such an insult:

    http://initforthegold.blogspot.com/2008/02/first-big-surprise.html

  16. #16 Nick Barnes
    2008/02/22

    Looks like the melt season has started.

  17. #17 Nin
    2008/03/12

    I’m intrigued to find out given the recent La Niña as this is exactly the data I need for my recently-rejected-from-Nature tropics paper. Ho well, at least it went to review. I’ll take another look at the figures and return to risk placing a bet ;)

  18. #18 P. Lewis
    2008/03/18

    Anyone for skating?