Nothing new, but M pointed me at Greenman on sea ice which has a quote from Wadhams (starts around 5:00, quote around 5:20 I think) that is the "the arctic will be ice free in summer in 20 years" or words to that effect (which got noted in my Arctic to be 'ice-free in summer'?.
I still don't believe it, not that that matters. Watch the video anyway for a glimpse of Wadham's / SPRI's rather haphazrd filing system.
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he seems quite certain when he gives the maximum of 20 years. He could have said 40 to be safer, I don't understand why they have to push shorter predictions like this. The Met Office prediction at the beginning of the year for 2009 being the 5th warmest year on record is a similar case of gambling with predictions.
If these predictions fail, which they could easily do, the statements and videos will be used by deniers to claim the predictions are always wrong (even if 2009 is 6th warmest, even if summer sea ice is gone in 40 years)
It was a shame that the catlin survey was mentioned in the video too..
The sea-ice claims will be gone in 20 years (or less!) are widely repeated all over the place. I am curious why you think they are incorrect? (if you have already answered this a link to your answer is more than enough). It would also be nice to get an idea as to what the range of estimates for an ice free summer are in the peer-reviewed literature. The alarmist predictions (for lack of a better term) get most of the attention, but may not be the most common prediction from the sea ice experts.
Thanks
[Opinions differ. The wikipedia article http://en.wikipedia.org/wiki/Arctic_shrinkage to which I've contributed says "Projections of sea ice loss suggest that the Arctic ocean will likely be free of summer sea ice sometime between 2060 and 2080" and sources that to http://www.nature.com/ngeo/journal/v2/n5/abs/ngeo467.html which I think is reasonable -W]
Fred, predictions can easily fail yes. Should this be seen as an opportunity for science to advance though understanding errors or an opportunity for deniers? You seem to be placing deniers into a position of being more important than science. That might be what the deniers want but it seems a strange order of priority to me.
Dan,
William is willing to bet against mainly gone by 2020.
http://scienceblogs.com/stoat/2007/12/betting_on_sea_ice_following_t.php
2030 may well be too long to bet over. It isn't yet clear how much William is coming back into the range of others eg see reply to post 20 at
http://scienceblogs.com/stoat/2009/10/sea_ice_round_up.php
Part of William reasons come from a paper of his:
Schroeder, D., and W. M. Connolley (2007), Impact of instantaneous sea ice removal in a coupled general circulation model, Geophys. Res. Lett., 34, L14502, doi:10.1029/2007GL030253
http://www.agu.org/pubs/crossref/2007.../2007GL030253.shtml
[Thanks. It is so easy to forget stuff -W]
Thanks for the answers. Now I have some reading to do:)
The 2060 to 2080 stuff is model projections (exception noted below). Up until the 2007 melt season there seemed to be pretty good agreement on those.
2007 threw that near-consensus for a loop. Now many speak in terms of 2030 (this is e.g. the official NSIDC line), but as far as I know that's all seat-of-the-pants stuff.
The one modeling study to show near-term loss (Maslowski) still hasn't been published, but he says the reason for the difference is that his model has the fine scale needed to correctly reflect the effect of warming currents from the south. Note that there's no inconsistency with William's paper.
If there's still a strong El Nino next spring it'll be interesting to see what the ice does. IMHO it won't take much to make it go away.
Unfortunately, when it does happen I'm afraid the object lesson will be pretty well lost. The AO will be ice-free (for a given value of "free") only briefly, the yahoos will natter about how quickly the ice started forming again, there still won't be reliable blue-water navigation, any knock-on climate effects will be subtle (for some years, anyway), and the following summer or two probably won't go ice-free.
IMHO those looking for climate change thrills will probably find more reward watching (no particular order) drought patterns, glacier loss and monsoon behavior.
IIRC, models discussed in AR4, showed "climatic" ice-free summers in the Arctic Ocean late this century or even early the next. The consensus in the ice modelling community now points much earlier.
[I disagree. I don't think you have any source for this "consensus" -W]
I agree with Steve Bloom, much depends on one's definition.
2007 was an El Nino year and 2008-9 saw extended La Nina conditions. When you take that into account, there is some evidence of accelerated ice loss in the years since AR4.
Ice free in 2013? Probably not, but I'd be very surprised if AR5 (to be released in 2013 with a cutoff presumably at end of 2011) did not show marked change in projections from AR4.
Anything from Maslowski et al. more recent than this?
Symposium on Drastic Change in the Earth System during Global Warming, Sapporo, Japan, 24 June 2008
http://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/34395/5/Maslowsk…
Crandles you, Wm, and I seem to appreciate the state of the system similarly. My concern has been that the 07 event was a monkey wrench in the works. Iâm now a bit more comfortable that the 07 reduction didnât produce an immediate tipping point in the trajectory.
Iâve also been wondering about the ultimate climatic impacts, more the consequences for the later part of the lives of Williamâs brood, than the symbolism - the cannary no longer able to twitter â represented by that ice free surface. I viewed with interest when our host posted the results of a model run (when he was a keeper of such critters) and his noting that not much changed, concerning rain patterns, if I recall, with the ice gone.
I donât see attempts to quantify the changing albedo consequences, more just reciting the âsummer will be ice freeâ meme and projections for the timing. Someone more famililar with the published material wish to correct me? Hank?
Reviewing the patriarchâs older posts, I do see a mention on something thatâs been a tick under my feathers, the sesasonal aspect.
Albedo change lags irradiance by close to 3 months. For the period of increasing sunlight at the surface, the ice, although declining, is still largely present for the bulk of the time period, and, as reduction of ice area proceeds energy input falls rapidly after its peak, roughly as the inverse of the area with lowered albedo.
Additionally, latitude matters. The number of atmospheric molocules in the direct path for a photon leaving the sun and the Earthâs surface is quite different for a location at high latitudes and for a tropical one, as the slant angle decreases poleward. While seasonal photo period lengthens toward the planetâs axis points, a high latitude's solar noon is still comprable to a tropical mid-morning for surface insolation at best.
Finally, the particular geography at the top of the northern hemisphere limits that ice/open water system. For much of period of reduction in ice area, the North Atlantic is the only major area for response. Very crudly, thatâs only a quarter of the iceâs circumference. Near peak ice coverage, some additional areas of the globe freeze for a while, but when they open thereâs not much else for a time, and this is when a significant fraction of the irradiance occurs. Possibably of greather consequence than albedo may be increased release of methane to the atmosphere, through seasonal extension of the period above freezing for the surrounding land mass, and lowering the clathrate hydrate occurance depth. Thereâs a lot of continental shelf.
DC, I don't think any of the GCMers have changed their views as yet. NSIDC and a few others like 2030, but as I said that's a seat-of-the-pants attempt to account for the aberrant last few years and is hardly the basis for a new consensus. So far as I can tell the only existing consensus is that the AO definitely will *not* have it's first ice-free period between 2030 and 2069. :)
Thanks, Hank, I hadn't seen that. It's a pretty good list of collaborators, and interestingly seems to imply that Marika Holland thinks the CCSM3 results are off track (noting that this is the model that came closest to being right about the recent trend). Has this team been working to integrate Maslowski's regional model with CCSM3, and is that why Maslowski hasn't published? The world wonders.
I'd guess that since Maslowski's at the Navy Postgraduate School, some of the source material may not be publicly available. But that's just speculation on my part.
There may well be other more recent work, I spent about 10 seconds with Scholar and I didn't try most of those names -- any of them could be publishing separately too.
Joe Romm has a new Artic sea ice post up. In addition to the new record low for this date (attributed to warm winds), Canadian scientist David Barber reports that the large pack of older multi-year ice normally found in the eastern Beuafort Sea has broken up into "rotten" ice. NSIDCers comment.
[I've asked JR is he wants to increase our bet :-) -W]
So, you still betting?
You can't turn your back on this stuff very long.
http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
True, but so far, the "what does it mean" in the near term is questionable.
OK, but that's a relatively small sample.
Actually, what we need is ice volume, not extent, accurately, and reliably ...
Robert Grumbine has posted suggesting that ice has recently been overestimated
But, really, I think sitting back and watching the next five years will tell us more.
What Hank might be referring to that 2009 is now setting low records for extent, at least according to ijis.
Month Day Year Ice Extent
1212200911105000
1212200711139375
Still a long time to September.
Jeff Masters of Wunderground has an interesting post up.
Actually he's had a string of good ones over the last couple of weeks.
He points out that using NSIDC's data, there was an all-time 10-day minimum in early November.
It's really close to the 2007 level again.
It will be interesting to see what the winter maximum will look like.
There was a nine day record low period on ijis ice extent from the 7th of November to the 15 of November as well.
I have not heard of any bets on this season's winter maximum. Say on ijis average for March?
What odds on 14*16^6 km^2? Or what level for even odds?
> "what does it mean"
Irresistable, that.
http://www.lanzbom.org/mr.natural_signs.jpg
http://southofheaven.typepad.com/south_of_heaven/images/2007/06/13/mr_n…
http://t1.gstatic.com/images?q=tbn:U28BrJoVoXZooM:http://i161.photobuck…