They indicate an average thickness of 1.4 meters, much less than Navy PIPS.
Hurry! Get PIOMAS some viagra!
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/
Gotta love dem Russkies!
This is little more accurate (taken from Arctic navigation maps). These in turn are taken from monthly/weekly surveys.
Seasonal ice extent 1900-2010
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.
US Polar Icebreaker ‘Healy’ webcam – 04/09/2012, 2:01:01 UTC, Lat: 82 57.7N Long: 164 51.3W, Air Temp: 28.8F
Considering the Healy’s in an area that shows as 90-100% concentration on the Uni Bremen maps, there shouldn’t be any open water there to re-freeze.
Expontential decay or Gompertz? Place your bets..
Gon will continue to be a clone for left wing propaganda or will begin to think for himself? Place your bets.
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.
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:
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.
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.
Their latest published data is clear and unambiguous. Cut the crap.
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.
Their most recent published numbers are clear and unambiguous. Ice free by 2015
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.
Thanks for those links, Peter — the movie is really interesting.
> 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.
I included the link to their published volume numbers in this “article” Are you familiar with HTML links?
“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
Their data shows an exponential decline, which is exactly what you would expect as the ice gets thinner and less compact.
> 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).
Your dissonance is astonishing. The graph is their most recent data.
> 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.
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.
Come now, David Appell, we’re talking about a specific model made of supposedly specific calculations. Quit dancing around it: what specific assumptions do they make that give them cover to claim that their model is valid even though it doesn’t accurately model anything real?
Read their papers.
Doesn’t model anything real?
“To validate PIOMAS as a suitable tool to study future
sea ice responses, we examined its response to the past
atmospheric forcing. Compared to satellite observations, the
model overestimates ice extent of the Arctic Ocean defined
as the Arctic Basin and the Barents Sea (Figure 1d). Mean
model bias for September ice extent is 0.65 × 10^12 m^2.
Nevertheless, the simulated annual and September mean ice
extents are highly correlated with the corresponding satellite
observations over 1978–2009 (R = 0.87 and 0.91, respectively), with low RMS (root‐mean‐square) errors of 1 and 5%. The model captures winter ice edge locations for recent
years (Figures 2a–2d). It underestimates (overestimates)
summer ice extent in the Atlantic (Pacific) sector of the
Arctic Ocean for 2006 (2008), while it estimates well the
summer ice extents of 2007 and 2009 (Figures 2m–2p).”
— Zhang et al, GRL (2010)
You guys can argue aboutPIOMAS until the cows come home but now that CryoSat-2 is there we’ll get to see real measurements. Muchos exciting, teh ice is disappearing!
No, the ice has been gone since 2008. The experts said so http://www.norwegianmoose.com/2008/03/polar-ice-cap-melting-away-in-2008.html
Warm water can freeze faster than cold. It’s called the Mpemba effect and was known about for centuries. A good start is here.
Water is the strangest common substance known to man.
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