PIOMAS Trend – Ice Free August By 2015

 

(here)

They indicate an average thickness of 1.4 meters, much less than Navy PIPS.

About stevengoddard

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37 Responses to PIOMAS Trend – Ice Free August By 2015

  1. Hurry! Get PIOMAS some viagra!

  2. Josik says:

    Here’s a Russian site showing the Arctic ice from 1900: http://nwpi.krc.karelia.ru/e/climas/Ice/Ice_no_sat/fig1.gif
    More “frozen” information about the Arctic here: http://nwpi.krc.karelia.ru/e/climas/

  3. gregole says:

    PIOMAS has a couple more years until (1 They get real or (2 Arctic is truly ice-free in summer and not some purely psychological minimum area counted in millions of sq km.

  4. snafu says:

    US Polar Icebreaker ‘Healy’ webcam – 04/09/2012, 2:01:01 UTC, Lat: 82 57.7N Long: 164 51.3W, Air Temp: 28.8F

  5. Gon says:

    Expontential decay or Gompertz? Place your bets..

  6. David Appell says:

    Why are you assuming PIOMAS’s model is valid all the way down to zero sea ice? They’ve said it is not….

    • I plotted a graph of a trend. If their model is useless, alarmists should stop using it.

      Your dissonance is astonishing.

    • Peter Ellis says:

      More to the point, they actually did run a future projection, and it showed a sigmoid curve rather than exponential – as does every climate model out there. Tietsche et al 2011 has the clearest picture of things and (to my mind) shows the most likely shape of ice loss in the coming years. Check figure 1 here:
      http://www.agu.org/pubs/crossref/2011/2010GL045698.shtml

      • Peter Ellis says:

        What this shows is that as the Arctic loses ice, there’s a temporary plateau at around 4.5 million, corresponding to a summer minimum area covering the deep parts of the central basin – pretty much the same central triangle-ish shape we saw from 2007 through to 2011. Then, there’s a rapid collapse to ~1.5 million, which is the residual rump holding out against Greenland/Ellesmere island. Then, finally a second collapse to complete loss.

        This makes sense physically and oceanographically. It’s easier to warm the shallow seas around the basin, so the 4.5 million “triangle” over the central basin lasts longer than the outskirts. It’s much harder to lose the thickened / compressed ice at high latitudes in the Lincoln sea and around the pole, so that holds out longest of all. The various states of coverage are somewhat metastable, and the transitions between them are quite rapid.

        The worrying thing is that we seem to be progressing along the curve faster than predicted. I wouldn’t be at all surprised to see us fall to the ~1.5 million plateau before 2020. We’ll likely hang around that for a while though before losing the rest.

      • Their published data absolutely does not show what you are describing, which is the norm for climate science. Unmitigated BS.

      • Peter Ellis says:

        http://psc.apl.washington.edu/zhang/IDAO/z_movie_heff_proj.mpg

        This is published data on their website. Watch it. This is their actual prediction when running in forecast mode, as opposed to a dumb trend extrapolation. Bear in mind that this run is from several years ago, and has been on the web for at least two years, because I first watched it back then, and have pointed you at it before. PIOMAS has undergone important updates since then.

        Admittedly, PIOMAS is ahead of the Tietsche curve (which used a different model), but then again so is reality. The overall shape of the decline follows the same pattern I described above: an initial collapse to about 1/3 of the 2007 area, then a tailing off / plateau and a slower fall to zero. In this case, summer ice cover collapses to ~1.5 million by ~2017, and then dwindles, not actually reaching zero till ~2040 or so.

        One factor I note when comparing the model run to the last couple of years is that PIOMAS seems to substantially overpredict ice in the Beaufort sea, but underpredict it in the northern Kara and Laptev seas. I don’t know if that’s still the case in more recent versions of the model, however.

      • Peter Ellis says:

        Or there’s their recent published paper, using a newer version of the model, which is quite a lot more cautious. I think they’ve applied some unrealistic forcings there (runs A1 and B1 essentially assume that all the temperature change since 1948 is random variability), such that only their most pessimistic forecast is realistic, but that’s my opinion, not theirs. In the most pessimistic estimate, ice drops to ~2.5 million by 2025, but still hangs on until past 2050, just much thinner than today.

        http://www.agu.org/journals/gl/gl1020/2010GL044988/

      • Peter Ellis says:

        Steve, you seem to have a conceptual difficulty between their model of the current state, and a future prediction.

        If I put a mug of water at 20 degrees in the freezer, it will lose heat at (say) 5 degrees per minute at the start of the process. Does that mean it will freeze solid in 4 minutes? No, because it slows down. That doesn’t mean an initial model saying “it is falling at 5 degrees per minute” is wrong. It just means you can’t naively extrapolate the curve.

        The bottom line is that PIOMAS predicts a sigmoid (S-shaped) decline in summer ice extent and volume. Currently we are on the fast bit of the curve, but it is predicted to level off soon. If you extrapolate simply from the top part of the curve, it is you who’s being dumb.

        • The fact that they are trying to cover all their bases with ambiguity is pretty pathetic. As the ice gets thinner, melt should accelerate exponentially. You know that and your attempts to obfuscate are lame.

      • David Appell says:

        Thanks for those links, Peter — the movie is really interesting.

      • David Appell says:

        > Their most recent published numbers are clear and unambiguous. Ice free by 2015.

        What is the publication reference?

        The 2010 paper Peter mentioned does not project zero September volume until around 2040.

      • David Appell says:

        “The projected September ice extents are subject to interannual fluctuations in association with the historical CV [Climate Variability] incorporated in the atmospheric forcings (Figures 1d and 2). The fluctuations remain significant approaching 2050. Thus, even if the projected September ice coverage falls to a particularly low level or below 1 × 10^12 m^2 in a certain year before 2050, it is likely to rebound substantially in later years. This suggests that it is difficult to pinpoint a particular year before 2050 from which the Arctic Ocean would be and remain ice free in summer.”
        — Zhang et al, GRL 2010
        http://www.agu.org/journals/gl/gl1020/2010GL044988/

      • David Appell says:

        > I included the link to their published volume numbers in this “article”

        The link was to their data. The projection is yours, not theirs. Their’s is much different (see Figure 1e in their 2010 paper that Peter linked to).

      • David Appell says:

        > Their data shows an exponential decline.

        Actually the trend from 1979 looks more linear, but *their* projection is that it won’t continue. You could actually read their paper and quote what they write, or just keep repeating your extrapolation as if it were theirs.

    • David Appell says:

      I didn’t say their model was useless — I said it has limitations. All scientific calculations make certain assumptions; if those assumptions fail in some domains, the calculation is useless.

  7. tckev says:

    Warm water can freeze faster than cold. It’s called the Mpemba effect and was known about for centuries. A good start is here.
    http://en.wikipedia.org/wiki/Mpemba_effect

    Water is the strangest common substance known to man.

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