Or so says some spam for terradaily that made it to my inbox (which is just a rehash of the Berkley press release, though thankfully without the stupid flood picture). This is obvious b*ll*cks, as google shows. The wiki page is a bit rubbish, largely because the only example anyone can ever think of is the Younger Dryas, and we aren't going to have another one of those (yes yes I know). Its certainly the only one terradaily can think of. Woods hole too. And there is a whole NRC report on ACC. And indeed if you look for "rapid" climate change you'll find Spencer Wearts history.
But TD is pushing a new programme called IMPACTS, and they say: "climate change has occurred with frightening rapidity in the past and will almost certainly do so again" which seems just a bit strong. But they have decided to investigate four potential ACC's:
1 instability among marine ice sheets, particularly the West Antarctic ice sheet;
2 positive feedback mechanisms in subarctic forests and arctic ecosystems, leading to rapid methane release or large-scale changes in the surface energy balance;
3 destabilization of methane hydrates (vast deposits of methane gas caged in water ice), particularly in the Arctic Ocean; and
4 feedback between biosphere and atmosphere that could lead to megadroughts in North America.
1 is exciting, but probably isn't a runner; reading further down I think it just amounts to trying to model ice shelves properly, which as they say of western civilisation "might be a good idea". 2 and 3 are probably OK, methane is in the news recently. 4 doesn't excite me but then I don't live there and I'm very insular.
Just to be clear: I've no objection to research on rapid climate change, just their pretence that this is a new thing, which I find irritating.
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PRetense, from the PR people (sigh) -- they apparently wrote "climate change" where the modeler said "extreme weather"!
From the Lawrence Berkeley Lab page:
---------
Collins. "For example, of the major threats to human health from global warming, the worst is malnutrition - but the second worst is extreme weather!"
... "Modeling a specific region with a specific set of circumstances in high resolution and making a solid prediction of what's going to happen in the next few decades ...." he says. "Those concerned with the effects of climate change on humans have never asked modelers to do this before. We hope that IMPACTS will demonstrate that it can be done."
[Yeah, well thats b*ll*cks too. People *ask* for that stuff all the time; but it can't be delivered. Nor will it be deliverable in 5 years time either, assuming that by "solid" he means "fairly likely to be correct" :-) -W]
It is SO hard to get steady substantial funding for this stuff from DoE, and it is really hard to get the National Labs to actually cooperate -- and outside the science community, people don't have a clue that things can change fast -- so I think it's great. As for being "fairly likely to be correct" -- the alternative to doing something substantial that can be criticized and improved is...?
So I don't quite get the post. Getting this work funded is bad? Trying to make people aware that AGW might not be nearly as gradual and "put-offable" as they think, that's bad?
You want abrupt climate change? What about a reversal of the Hadley cells? As I understand it anti-Hadley circulation is potentially stable too, although I have no idea what it would take to flip the system.
p[Doesn;t sound very plausible at all. In fact it sounds completely wrong. Who says so? -W]
P.S. I just read Lovecrafts "At the Mountains of Madness". Is that what Antarctic researchers use to scare each other during the long dark night?
> Lovecraft ...?
Stross!
http://www.infinityplus.co.uk/stories/colderwar.htm
---excerpt---
The moonlit shores of Lake Vostok
The metal pier is dry and cold, the temperature hovering close to zero degrees Fahrenheit. It's oppressively dark in the cavern under the ice, and Roger shivers inside his multiple layers of insulation, shifts from foot to foot to keep warm. He has to swallow to keep his ears clear and he feels slightly dizzy from the pressure in the artificial bubble of air, pumped under the icy ceiling to allow humans to exist here, under the Ross Ice Shelf; they'll all spend more than a day sitting in depressurization chambers on the way back up to the surface.
There is no sound from the waters lapping just below the edge of the pier. The floodlights vanish into the surface and keep going -- the water in the sub-surface Antarctic lake is incredibly clear -- but are swallowed up rapidly, giving an impression of infinite, inky depths.
...
They're waiting for a rendezvous.
"Five hundred yards,'' reports one of the techs. "Rising on ten.'' His companion nods. They're waiting for the men in the midget sub drilling quietly through three miles of frigid water, intruders in a long-drowned tomb. "Have 'em back on board in no time.'' The sub has been away for nearly a day; it set out with enough battery juice for the journey, and enough air to keep the crew breathing for a long time if there's a system failure, but they've learned the hard way that fail-safe systems aren't. Not out here, at the edge of the human world...
----end excerpt---
Full text available at the link.
[Shurely shome mishtake: Lake Vostok is hundreds of miles from the Ross Ice shelf -W]
The reversal of the Hadley circulation was from a discussion after a seminar that diverged into more speculative scenarios. I can't guarantee how plausible it is, but it did work in a simple box model.
[But box models have no physics. The Hadley cell is driven by heating; you can't reverse in the real world. Or so I claim -W]
> shurely
You may find one or two other things in the story that don't match consensus reality (grin).
How about a number 5?
http://www.eurekalert.org/pub_releases/2008-06/uoca-gic061808.php
[Isn't that the Younger Dryas again? -W]
I think as we see less ice area/thickness and increased ocean warming (and crucially more humidity in the Arctic), at some stage atmospheric circulation could reorganise. I can't work out why what is happening in the Arctic will not in due course affect NH climate (even SH). More than that; the sort of atmospheric change involved in a transition to seasonally ice-free state seem to be just the sort of factor that could change atmospheric circulation patterns.
The simplest analogy I can think of is a ball bearing dropped into a grid of pins hammered into a board (like in some pinball machines). Move the place you drop the ball and the path changes, even small moves can make big changes in path.
That said, I don't buy Hadley Cell Reversal either.
OT
Guillermo Del Torro is trying to get a film of "At The Mountains of Madness" off the ground - now that would be good. "The Colour Out Of Space" directed by Tim Burton would be even better.
I can't imagine the Hadley Cells reversing but what about the Arctic polar vortex. Convection is mainly caused by water vapour due to its lower density, and latent heat. With no sea ice in the Arctic during summer then not only will there be nothing to cool the lower air causing high pressure and a descending vortex, the surface will be wet with plenty of solar energy to cause evaporation and convection.
[Not quite... convection outside direct solar heating is due to water vapour condensing and releasing heat, driving upwards motion which cools the parcel thereby allowing more condensation and more latent heat release... nothing to do with WV having a lower density.
Finally, you make the mistake that everyone does: the sfc of sea ice is just as "wet" as water is, as far as evap of water is concerned -W]
William,
Yes it's the YD again. It's frustrating being limited by the limitations of proxies, but that's the way it is.
I consider that issue irrelevant from p.o.v. of the direct atmospheric impact. Of relevance -
1) Thinner and more broken ice allows greater sensible and (crucially)latent heat fluxes from ocean to atmosphere.
[Yes. But only because the ocean is warmer - not because it is wetter -W]
2) Larger areas of open ocean during the summer represent another heat input into the Arctic Ocean.
Some extra-arctic atmospheric impact is inevitable (e.g. Bhatt et al "The Atmospheric Response to Realistic Reduced Summer Arctic Sea Ice Anomalies"), my suggestion of atmospheric circulation reorganisation is speculative.
Either way we'll find out shortly. IMO the Arctic will be virtually summer-ice-free within about 10-20 years - I'm sticking to my "around 2018 at the earliest". And we don't need to arrive at a seasonally ice-free state for the atmospheric impact to start. ()
Paywall free - Bhatt et al: http://www.cdc.noaa.gov/people/michael.alexander/publications.html 3rd paper down, 2 pdfs - text and graphics.
Agreed. - Well I'd be wrong if I didn't.
I have a paper somewhere that describes 500 to 1000 watt/sqmetre fluxes(latent + sensible) into the atmosphere from leads in the winter. But as I can't find it (typical) here's some summer SST anomalies for < a href="http://sharaku.eorc.jaxa.jp/AMSR/polar_sst/2008/P1AME0808PNSST000600ANOML.png" >Aug 2008< /a > / < a href="http://sharaku.eorc.jaxa.jp/AMSR/polar_sst/2007/P1AME0708PNSST000500ANOML.png" >Aug 2007< /a > / < a href="http://sharaku.eorc.jaxa.jp/AMSR/polar_sst/2006/P1AME0608PNSST000400ANOML.png" >Aug 2006< /a > / < a href="http://sharaku.eorc.jaxa.jp/AMSR/polar_sst/2005/P1AME0508PNSST000400ANOML.png" >Aug 2005< /a > yadda yadda yadda.
< a href="http://sharaku.eorc.jaxa.jp/cgi-bin/amsr/polar_sst/polar_sst.cgi?lang=e" >Source< /a > of above SST anomaly images.