Thanks everybody ... this is all very helpful. The only point nobody has
commented on is the BBC's statement that "Recent work at NOC suggests it
would be a quick change - if it happen."
If that is correct, it is of considerable relevance - more so than most
climate change dynamics - to a crisis forum.
Most worrying, it would lend my wife ammunition that we sell up in Scotland
and move to her native south of France. No more whisky!
If anyone has further info on that NOC work, please feed in.
A.
-----Original Message-----
From: Discussion list for the Crisis Forum
[mailto:[log in to unmask]] On Behalf Of David Cromwell
Sent: 26 January 2011 11:47
To: [log in to unmask]
Subject: Re: Extraordinary bear swim ... and "Gulf Stream" turn-off risk
(again)
Bob wrote:
' A paper in Nature a few years ago suggested that it had found evidence
that such a weakening of the THC had been detected, but later research has
suggested this was probably not the case.'
That's right. A 2005 Nature paper by Harry Bryden et al. found evidence of
weakening of the Atlantic MOC between 1957 and 2004 using 'snapshot'
estimates from ship hydrographic data:
Bryden, H.L., Longworth, H.R. and Cunningham, S.A. (2005) Letter. Slowing of
the Atlantic meridional overturning circulation at 25° N. Nature, 438,
(7068), 655-657. (doi:10.1038/nature04385)
A later study led by Harry's colleagues in Southampton found that 'a large
part' of the apparent slowdown was likely an artefact ('aliasing') of the
large seasonal variations in the MOC:
Kanzow, T., Cunningham, S.A., Johns, W.E., Hirschi, J.J-M., Marotzke, J.,
Baringer, M.O., Meinen, C.S., Chidichimo, M.P., Atkinson, C., Beal, L.M.,
Bryden, H.L. and Collins, J. (2010) Seasonal variability of the Atlantic
meridional overturning circulation at 26.5°N. Journal of Climate, 23, (21),
5678-5698. (doi:10.1175/2010JCLI3389.1)
From hearing Harry's comments in seminars, my understanding is that he
believes his study did detect a real decline in the MOC (would presumably
need further work to establish this) . So - and again this is my
interpretation - it looks like the jury is still out.
There's a major conference taking place in Bristol this coming July:
http://www.noc.soton.ac.uk/rapid/ic2011/
Watch this space....
David
-----Original Message-----
From: Discussion list for the Crisis Forum
[mailto:[log in to unmask]] On Behalf Of Kelly-Gerreyn B.A.
Sent: 26 January 2011 11:26
To: [log in to unmask]
Subject: Re: Extraordinary bear swim ... and "Gulf Stream" turn-off risk
(again)
This is not my area of expertise but it is of my colleagues. If my chats
with them are properly interpreted by me, models have to be pushed to
extremes before the MOC slows down considerably. These extremes do not seem
to be thought of as realistic/probable at this time. Hence, shutting down
does not seem to be a scenario that has a general consensus. But don't quote
me!
If I hear more I'll post it.
Cheers Boris
-----Original Message-----
From: Discussion list for the Crisis Forum
[mailto:[log in to unmask]] On Behalf Of Bob Ward
Sent: Wednesday January 2011 11:12
To: [log in to unmask]
Subject: Re: Extraordinary bear swim ... and "Gulf Stream" turn-off risk
(again)
Alastair,
I think the broad consensus is that disruption of the thermohaline
circulation in the Atlantic (technically referred to as Meridional
Overturning Circulation) remains a very real risk if climate change
continues unabated, but such an impact is not imminent. A paper in
Nature a few years ago suggested that it had found evidence that such a
weakening of the THC had been detected, but later research has suggested
this was probably not the case. Here is the discussion in the last IPCC
report in 2007:
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch5s5-3-2-1.html
Somebody on this list may be able to offer an update on the latest
research findings in this area.
bob
Bob Ward
Policy and Communications Director
Grantham Research Institute on Climate Change and the Environment
London School of Economics and Political Science
Houghton Street
London WC2A 2AE
http://www.lse.ac.uk/grantham
Tel. +44 (0) 20 7106 1236
Mob. +44 (0) 7811 320346
-----Original Message-----
From: Discussion list for the Crisis Forum
[mailto:[log in to unmask]] On Behalf Of Alastair McIntosh
Sent: 26 January 2011 11:03
To: [log in to unmask]
Subject: Re: Extraordinary bear swim ... and "Gulf Stream" turn-off risk
(again)
This about ice research on BBC web today -
http://www.bbc.co.uk/news/science-environment-12279028
I am taken by its claim that:
"Warmer and fresher water does not sink so readily; and this could could
turn off the "ocean conveyor", a picture painted in heightened Hollywood
colour in the movie The Day After Tomorrow. Overall, if these changes...
contribute to a lowering of the salt content of the North Atlantic, it
could
have a major impact on the entire planet - from significant temperature
drops in Europe to intensified monsoons in Asia," said Richard
Zimmerman, a
bio-optics specialist at Old Dominion University in Norfolk, Virginia,
US.
Recent work at NOC suggests it would be a quick change - if it happen."
In previous discussion on this forum (a year ago) the view seemed to be
that
"Gulf Stream" turn off risks had been overstated. Is that position
changing,
does anybody know?
Alastair.
-----Original Message-----
From: Discussion list for the Crisis Forum
[mailto:[log in to unmask]] On Behalf Of Bob Ward
Sent: 26 January 2011 09:55
To: [log in to unmask]
Subject: Re: Extraordinary bear swim
Dear John,
Many thanks for this interesting message. I didn't see the news item,
but if the interviewee who "ducked" the question was a scientist, I can
understand why.
Climate change is about long-term trends, and single events and
anecdotal information are not really very good indicators of the
presence or absence of any trend.
The story of one polar bear found swimming for a long time is not really
very good evidence about the impact of retreating Arctic sea ice. A
large population of bears shown to have changed their behaviour over
many years might be more convincing. This story might be illustrative of
a trend, or it might just be about a bear that got lost.
The fate of the polar bear has become a pawn in the highly politicized
debate about climate change, particularly in the United States. It is
not hard to conclude that retreating Arctic ice must be having an impact
on the polar bear population - but whether you can yet detect that
impact yet is another question entirely. I think it would be much better
to find some solid research papers which have looked at impacts on polar
bear populations and use that as the basis for any campaign.
Bob Ward
Policy and Communications Director
Grantham Research Institute on Climate Change and the Environment
London School of Economics and Political Science
Houghton Street
London WC2A 2AE
http://www.lse.ac.uk/grantham
Tel. +44 (0) 20 7106 1236
Mob. +44 (0) 7811 320346
-----Original Message-----
From: Discussion list for the Crisis Forum
[mailto:[log in to unmask]] On Behalf Of John Nissen
Sent: 25 January 2011 23:24
To: [log in to unmask]
Subject: Extraordinary bear swim
Hi all,
At 10.40 pm on BBC Radio 10 'oclock news tonight, there was a news item
about a female bear in Alaska who had been telemonitored swimming for 9
days non-stop, losing 20% of her body-weight. She started off swimming
with a cub, which was presumed to have died on the way. The interviewer
asked questions about whether the bear was expecting to find sea-ice
much sooner, and whether the sea-ice had retreated due to global
warming. The interviewee completely ducked the questions! It is as if
it is now taboo to say anything about global warming. I think this
could be a repercussion of the climategate affair. Scientists are just
too afraid to say anything that might be seized by climate deniers,
because they have been so vociferous. Isn't it important that we should
tell the world that sea ice is at a record low extent for this time of
year, has been steadily diminishing in volume since 2007 and is now in
such a fragile state that it could suddenly disappear during one summer
within the next few years? It is thus unlikely that polar bears will
survive in their Arctic habitat for much longer.
What do you think? Could this bear story be a wake-up call for action
to save the Arctic sea ice? I am hoping that you, Kieran, from the
Center for Biological Diversity will take this up. The Arctic is an
important part of the Earth's climate system and the Arctic ecosystem is
important for the marine food chain. The sea ice is part of the
planet's thermostatic control mechanism. It would be extremely
dangerous to lose it. Scientists expect massive amounts of methane to
be released from permafrost as the Arctic continues to warm, causing an
addition to global warming of many degrees.
Could a bear prove to be the 'canary in the mine' for unbearable climate
change?
John
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