JF points out Arctic Ice Retreating More Quickly Than Computer Models Project, which says "Arctic sea ice is melting at a significantly faster rate than projected by even the most advanced computer models... the Arctic's ice cover is retreating more rapidly than estimated by any of the 18 computer models used by the Intergovernmental Panel on Climate Change (IPCC) in preparing its 2007 assessments". Its here if you have access.
Of course the question is what does this mean? The press release goes for "This suggests that current model projections may in fact provide a conservative estimate of future Arctic change, and that the summer Arctic sea ice may disappear considerably earlier than IPCC projections".
Thats one answer as the paper says: the models may be too conservative in their response; which put another way is "the models are wrong". You could support this by the rather large spread of sea ice that the models produce. Or, it may mean that a substantial component of the current trend is variability. Who knows which is correct?
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Hi William and all other good bloggers,
please make a big posting urging American viewers not to watch the Exposed special with Glenn Beck.
No one should watch it because Glenn Beck is a denier! Please also ask people to avoid TV tonight on RealClimate.ORG.
Thanks, Eli Hamster
[OK, and I've cut the times to amke sure... -W]
To save the denialists time:
"The models are broken, so we don't know anything about what the future ice coverage will be like, so there's nothing to worry about."
> eli.com
That you, Lubos? I'd bet the IP address used isn't from E.L.I., a company selling used VAXen. Cute, though.
Someone obviously believes in cross-species dating....
To the extent that Holland is trashing the models, she's also one of the leading trashees. Eyeballing the graphic in the link, it's been about five years there was contact between the observed trend line and the lower bound of the standard deviation of the combined models. That raises the question of whether there are individual models that do better, although since that wasn't mentioned it would seem not. Since this paper is really just formalizing an analysis that Maslowski at least has been pointing out publicly for a couple of years, it seems as if the sea ice modeling community would have alredy made some efforts to close the gap. Is that the case, and if so was it just (like so many things) too late for the AR4? What's the current state of thinking in the community on this issue?
Regarding Glenn Beck, it's not so much that he's a denialist but that he is a denialist by way of a generally wingnut approach to the world. That would of course appeal to Lubos even more.
Re ER's comment: Hambits? Rabsters? The mind fair boggles...
William: I know the work continues constantly to improve models representations of sea-ice, but I do get the impression that many of them use slabs and finite boundaries, so the ice isn't treated realistically, unless it is the focuas of attention.
[Errrm... within GCMs, sea ice is treated (in general) as a viscous-plastic substance on the ocean model grid. But any honest assessment of the models would show a very wide variation in the control climates -W]
I also get the sense, from reading the Immortalised Rapley, the last ten or so papers in the journals, and the specialist cryosphere journals, that the signs are now getting worse for the Arctic, and worrying for the Antarctic.
[For the Ant, seaice is growing a bit, not shrinking -W]
Yes, there are many 'don't knows' at the moment, but there are enough signals (primary and secondary), all pointing the same way; mass loss, pooling, ablation, glacier outflow and subsurface stream flow, freshening and old ice loss, to tentatively conclude that a new process is already under way, as a result of GW, which we have little hope of reversing or slowing down.
If this is the case, how long will it take before this becomes a recognised phenomenon more widely. More to the point: it worries Rapley & Hansen; does it worry you?
Me, I've just changed my underwear. :)
[It remains hard to know. Yes there are various glacier speed-ups, but at the moment at least these aren't a big effect even if they continue -W]
Fergus, the rumor is that the ice experts (glacier if not sea ice) are in a blind panic about trends (well, a stodgy, tweedy sort of blind panic, but we have to allow for context). We shall see how the papers reflect this in the next year or two.
BTW, according to the SF Chronicle story today, Holland notes that her own model was the pick of the litter (although presumably still somewhat off).
William: thanks for the explanation of the models. On the Ant., I wasn't thinking of the sea-ice extent (sorry that wasn't clear), but things like the discovery of ice-lakes and streams, which serve to accelerate glacier movement; the discovery of ice-quakes which have increased in frequency and correlate with seasonal temp. changes, melt rates at the King George VI & the Piney place (what's its name?), & the idea that freshwater is pumping into the Southern Ocean & is connected with the Pacific and Indian Ocean deep layers.
I'll take your answer as meaning: 'things to look out for, but the process is still relatively small/slow'; is that fair?
I am not an expert on anything, but I use very simple models to forecast NFL football games and I have won several Las Vegas contests. The map is not the territory and the model is not reality. If the model is consistently wrong when compared to reality, then the model is wrong. However, I wonder how the arctic ice is measured. The arctic ice measurement may also be the result of a model, in which case we have no clue to which model (the forecasting model or the arctic ice data model) is wrong. They could both be wrong. A model can only be "proved" by testing predictions versus reality. So the first question to answer is how real is the reality of early arctic ice melt. My guess is that the method of collecting ice data has changed over the last 50 years, and this may have affected the numbers.
[Nowadays, ice is measured by satellite by microwave, and this is calibrated in various ways, including comparisons to ship measurements. So yes, there are various changes in the input data, especially around 1979, but whether this results in a jump in the total extent is another matter -W]
WE NOW KNOW, A YEAR LATER, THAT THE RAPID SEA ICE RETREAT WAS FOLLOWED BY A COLD WINTER AND SEA ICE ADVANCE. IT WAS VARIABILITY. ALL THOSE HYPING THE FALSE CLAIM THAT IT MEAN THE MODELS WERE "CONSERVATIVE" WERE WRONG.
The models that the IPCC use do not properly account for natural climate variability. THEY ARE WRONG. NASA post-fact said that it was a wind pattern that caused the falloff.
Arctic sea ice is now above normal, and this amazing recovery not only erases last years sea ice retreat, it, along with coldest winter in over a decade, point to a complete reversal that contradicts climate model predictions.
it's time we started looking at the facts and point out that the IPCC emperor has no clothes, er, climate data to back up their models. The models are wrong.
See:
http://sciencepolicy.colorado.edu/prometheus/archives/climate_change/00…