Sunday, May 6, 2012

3891.txt

cc: tim.carter@vyh.fi, zkundzeatXYZxyz.poznan.pl
date: Mon Jan 29 11:54:52 2001
from: Mike Hulme <m.hulmeatXYZxyz.ac.uk>
subject: Re: Abrupt change in THC simulated
to: PARRYML@aol.com, nlearyatXYZxyzcrp.gov

Dear All,
The WGI SPM states:
"......... even in models where the thermohaline circulation weakens, there is still a
warming over Europe due to increased greenhouse gases. The current projections using
climate models do not exhibit a complete shut down of the THC by 2100. Beyond 2100, the
THC could completely, and irreversibly, shut down in either hemisphere if the change in
radiative forcing is large enough and applied long enough."
Thus notwithstanding the recent Nature papers from the PIK and GFDL modelling groups, it
would appear odd if WGII Chapter 13 on Europe presented a back-of-the envelope impacts
assessment for Europe for an event (cooling presumably is what everyone tends to have in
mind) which WGI in the same IPCC assessment says there is no evidence for. The situation
beyond 2100 may be different indeed, but are we seriously contemplating quantitative
impacts/adaptation assessments for more than 100 years into the future? In any case,
no-one has done this yet so we can't assess it. Also, the slowing down of warming rates
over NW Europe because of THC weakening is *basically* represented in standard scenarios -
such as those we use - using coupled OAGCMs.
I would maintain our position, although clearly recognising the science will change in the
months/years ahead as we become better able to quantify the circumstances under which NW
Europe may actually *cool* because of THC behaviour rather than simply warm more slowly (I
also think people get a bit hysterical about 'abrupt' changes in this context, as though NW
Europe climate could become like the Hudson Bay in a few years!!). I think there is some
rich exploratory work to be done in this area, but I don't think the IPCC report is the
place to do it.
Mike
At 05:41 29/01/01 -0500, PARRYMLatXYZxyz.com wrote:

Neil
Zbysek and I , following reviewers comments in the summer, sought advice from
scenario authors Hulme and Carter on this. Our position has been that we
would incorporate THC effects if a) scenarios were produced for it and b)
this was agreed at co-chairman level. H and C view was strongly that
scenarios are not available and that to make superficial impact assessment
for this issue was not consistent with agreed WG2 content (see below). Z and
I have taken this to be the IPCC position. If it is not, please advise. If
it is likely to come up at Plenary, please also advise.
regards,
Martin
ubj: Abrupt change in THC simulated
Date: 26/1/2001 20:43:05 GMT Standard Time
From: nlearyatXYZxyzcrp.gov (Neil Leary)
To: zkundze@man.poznan.pl, parrymlatXYZxyz.com
Dear Martin and Zbyszek,
See the email below regarding simulation of THC shutdown. Apparently the US
government submitted comments on the SOD about the lack of coverage of this
issue in your chapter -- and are still concerned about its omission. Let
me know if you think any additions to your chapter are warranted.
See you in Geneva,
Neil
>Date: 19 Jan 2001 14:00:11 -0500
>Sender: Josh Foster <fosteratXYZxyz.noaa.gov>
>From: Josh Foster <fosteratXYZxyz.noaa.gov>
>Subject: Abrupt change in THC simulated
>To: Lauren Flejzor <flejzorleatXYZxyzte.gov>, Sally Kane <kane@ogp.noaa.gov>,
> David Jon Dokken <ddokkenatXYZxyzcrp.gov>,
> Michael Ledbetter <mledbettatXYZxyz.gov>, Neil Leary <ipccatXYZxyzcrp.gov>,
> Mike Hall <hallatXYZxyz.noaa.gov>, Jim Buizer <buizer@ogp.noaa.gov>
>X-Priority: 3
>MIME-Version: 1.0
>Reply-To: Josh Foster <fosteratXYZxyz.noaa.gov>
>X-MIME-Autoconverted: from quoted-printable to 8bit by earth.usgcrp.gov id
>OAA11383
>Status:
>
>Dear All,
>
>I just stumbled across an article based on work performed by Ronald
>Stouffer at NOAA/GFDL and and Alex Hall of the Lamont-Doherty Earth
>Observatory. They assert that they have recently generated a computer
>model run that has simulated (I believe for the first time) an abrupt
>change in sea currnet temperature in the North Atlantic--an abrupt climate
>event without forcing. The punchline of the article is that this work
>essentially represents a viable simulation of a shutdown of ocean
>convection around Greenland.
>
>This work tends to contradict assertions from the authors in the IPCC TAR
>WG2 Chapter 13 (Europe) that they choose not to cover the THC response
>issue because it had never yet been simulated in any AGCM.
>
>One of the main comments I entered about the Europe Chapter after the
>recent round of revisions to the TAR WG2 was that I thought it was
>questionable that the authors were ignoring THC response when the THC is
>heavily used as an example of abrupt change in other parts of the
>document. And as we know, THC overturn would have profound implications
>for Europe and the globe.
>
>Perhaps, they will have to come up with a different reason for not
>covering this issue.
>
>Do with this information as you will.
>
>Cheers,
>Josh
>
>--
>Joshua Foster
>International Program Development
>Climate and Societal Interactions (CSI)
>Office of Global Programs (OGP)
>U.S. National Oceanic and Atmospheric Administration (NOAA)
>1100 Wayne Ave., Suite 1210
>Silver Spring, MD 20910 USA
>Phone: 1-301-427-2089x173
>Fax: 1-301-427-2082
>Email: fosteratXYZxyz.noaa.gov
>[1]http://www.ogp.noaa.gov/
>
>text of article below
>==================
>TERRADAILY
>Computer Models Generate Extreme Climate Events
> Washington - Jan. 16, 2001
>[2]http://www.spacedaily.com/news/climate-01a.html
>
>When scientists run computer models to simulate climate events, they often
add
>elements, such as effect of volcanic eruptions, adding ice sheets, or
>altering the concentrations of greenhouse gases in the model's atmosphere.
>One NOAA
>scientist and his colleague discovered a large, abrupt climate event
>without the additions.
>
>"When I first saw the results, I thought that I had bad data," said Ronald
>Stouffer, a meteorologist at NOAA's Geophysical Fluid Dynamics Laboratory
>in Princeton, N.J. "I would never would have guessed the 'bad data' was a
>very interesting event."
>
>The "interesting event" is a severe and abrupt cooling of the North
>Atlantic Ocean near Greenland. The event will be described by
>Stouffer and Alex Hall of the Lamont-Doherty Earth Observatory in
>Palisades, N.Y. in the Jan. 11 issue of the science journal Nature.
>
>Stouffer and Hall found that an unusually long-lived atmospheric wind
>deviation leads to the northern North Atlantic Ocean and surrounding
>regions becoming very cold for 30- to 40-years.
>
>"We have a 15,000-year simulation," Stouffer said. "About the model
>year 3,100, there is a dramatic drop in the surface air temperature. It
>just happened spontaneously, which is what makes the event so interesting."
>
>Stouffer said that those researchers trying to detect human-influenced
> signals in climate change will be interested to know that the climate
>may generate more variability on its own than previously thought. He
>added that climate modelers will be interested to know that their
>models can produce large, abrupt climate events, without forcing
>changes. And, he noted that researchers studying paleoclimatology --
>the climates of the past -- may have a new explanation for some of the
>oscillations seen in ice core records. Some of these oscillations have
>no widely accepted explanation. The cooling seen in the ice core
>record 8,200 years ago is one example and resembles the event in
>the model.
>
>Stouffer and Hall's work traces the cooling to an abnormally intense
>East Greenland current caused by the wind deviation. As it flows southward
>along Greenland's east coast, it transports relatively cold, fresh Arctic
>water into the North Atlantic. The fresh Arctic water effectively shuts
>down the oceanic convection, which normally warms surface waters in the
>region.
>
>"Since the ocean surface is no longer being warmed by the deeper
>waters, it cools. As the waters cool, the overlaying atmosphere also gets
>colder," Stouffer said.
>
>Stouffer and Hall note in their paper that the probability of such an
>event happening in the near future seems low -- only one such event
> was found in the 15,000-year integration of the model. However, they
>note that the probability may be increasing.
>
>"First, nearly all coupled ocean-atmosphere models show adecrease in the
>high latitude surface salinity when greenhouse gases increase as has been
>the case for some time. The decreased salinity may make the region more
>susceptible to a large event,"
>
>Stouffer said. "Second, consistent with the observed 20- to 30-year
>increase in the real climate's North Atlantic Oscillation index is a
>strengthening of the northwesterly winds blowing across the East
>Greenland current. If this wind anomaly continues, it could set the stage
>for a dramatic climate event in the North Atlantic."
>
Neil A. Leary, Ph.D.
Head, Technical Support Unit
Working Group II
Intergovernmental Panel on Climate Change
400 Virginia Avenue SW, Suite 750
Washington, DC 20024 USA
General number: 1 202 314-2225
Direct number: 1 202 314-2224
Fax: 1 202 488-8678
email: nlearyatXYZxyzcrp.gov or ipccatXYZxyzcrp.gov
Subj: Re: THC Europe
Date: 18/10/2000 18:48:29 GMT Daylight Time
From: m.hulmeatXYZxyz.ac.uk (Mike Hulme)
To: PARRYML@aol.com, tim.carteratXYZxyz.fi
CC: zkundzeatXYZxyz.poznan.pl
My view is that we cannot assess non-existent material.
It is not so much the IPCC position as the fact that to date scientists
have not explored the consequences - it is a failing (if we call it that)
of science, not of the IPCC.
I doubt whether the TSU would help much here. The people who have been
pushing the TAR re. the THC collapse are people in WGII like Steve
Schneider and Barrie Pittock. I agree with Tim, that WGI have ducked the
issue of saying anything very loud about it.
In all this we should remember, and this is a partial reply to Qs on the
launch day, that most/all of the scenarios considered by the work assessed
in the TAR already *have* a weakening of the THC (since most coupled GCMs
show this). It is not a 'collapse' and it does not take us beyond
2100, when things under some scenarios may be different.
And we certainly are not yet in a position to say how likely such behaviour
is.
Worth noting that a new NERC Thematic Programme on the THC is likely to be
funded as from 2001, one objective being to 'provide scenarios for risk
assessment of the impacts of THC changes on climate'. Check out
[3]http://www.nerc.ac.uk/ms/THC/index.htm .
Mike
At 12:38 18/10/00 -0400, PARRYMLatXYZxyz.com wrote:
>Tim, Mike, Zbyszek:
>Following Mike's and Tim's comments, I think I am now back where I started
>which was to be able to state that it is the IPCC position (since you two are
>the scenario 'people' for WGII) that a) there are no scenarios for impacts of
>possible THC change, b)no assessment has been done AND c) THEREFORE THE IPPC
>HAS CONCLUDED NO ASSESSMENT CAN BE MADE OF IT AT THIS POINT.
>
>I am very happy if that is the position (which I think was\where we started 3
>years ago). I may have misunderstood Tim'spoint that the Polar ch and ch 19
>deal with THC change (but if it is to say no more than the para above, then
>we are all agreed).
>
>Regarding the phrase 'IPCC position'? Would it be wise to check that
>McCarthy /Watson have the same understanding as we do.
>
>The reason I would like to clarify this is the following: a) It is certain
>that readers of TAR will ask: What will be would be the effect of possible
>change in THC on Europe? Our answer would be that IPCC has not assessed this
>(because scenarios have not been developed nor impact assessments done). The
>riposte may be: Then why not, but that is a riposte to the IPCC not us ; b)
>on the other hand, Mike, Jorgen and I will be presenting the ACACIA results
>to a press \briefing on 1st November; and the same Q may well arise and we
>would then give the same response (since ACACIA is a an IPCC precursor).
>Correct?
>
>I think I am now clear about this, but I would like to be clearer about how
>far this is an IPCC position.
>Look forward to your replies,
>Martin
>
>Prof. Martin L. Parry
>Jackson Environment Institute
>University of East Anglia
>Norwich
>NR4 7TJ
>
>Tel: +44 (0) 1603 592 318
>Fax: +44 (0) 1603 593 896
>E-mail: parrymlatXYZxyz.com
>Web: [4]http://www.uea.ac.uk/env/jei
Subj: Re: THC Europe
Date: 18/10/2000 18:48:29 GMT Daylight Time
From: m.hulmeatXYZxyz.ac.uk (Mike Hulme)
To: PARRYML@aol.com, tim.carteratXYZxyz.fi
CC: zkundzeatXYZxyz.poznan.pl
My view is that we cannot assess non-existent material.
It is not so much the IPCC position as the fact that to date scientists
have not explored the consequences - it is a failing (if we call it that)
of science, not of the IPCC.
I doubt whether the TSU would help much here. The people who have been
pushing the TAR re. the THC collapse are people in WGII like Steve
Schneider and Barrie Pittock. I agree with Tim, that WGI have ducked the
issue of saying anything very loud about it.
In all this we should remember, and this is a partial reply to Qs on the
launch day, that most/all of the scenarios considered by the work assessed
in the TAR already *have* a weakening of the THC (since most coupled GCMs
show this). It is not a 'collapse' and it does not take us beyond
2100, when things under some scenarios may be different.
And we certainly are not yet in a position to say how likely such behaviour
is.
Worth noting that a new NERC Thematic Programme on the THC is likely to be
funded as from 2001, one objective being to 'provide scenarios for risk
assessment of the impacts of THC changes on climate'. Check out
[5]http://www.nerc.ac.uk/ms/THC/index.htm .
Mike
At 12:38 18/10/00 -0400, PARRYMLatXYZxyz.com wrote:
>Tim, Mike, Zbyszek:
>Following Mike's and Tim's comments, I think I am now back where I started
>which was to be able to state that it is the IPCC position (since you two are
>the scenario 'people' for WGII) that a) there are no scenarios for impacts of
>possible THC change, b)no assessment has been done AND c) THEREFORE THE IPPC
>HAS CONCLUDED NO ASSESSMENT CAN BE MADE OF IT AT THIS POINT.
>
>I am very happy if that is the position (which I think was\where we started 3
>years ago). I may have misunderstood Tim'spoint that the Polar ch and ch 19
>deal with THC change (but if it is to say no more than the para above, then
>we are all agreed).
>
>Regarding the phrase 'IPCC position'? Would it be wise to check that
>McCarthy /Watson have the same understanding as we do.
>
>The reason I would like to clarify this is the following: a) It is certain
>that readers of TAR will ask: What will be would be the effect of possible
>change in THC on Europe? Our answer would be that IPCC has not assessed this
>(because scenarios have not been developed nor impact assessments done). The
>riposte may be: Then why not, but that is a riposte to the IPCC not us ; b)
>on the other hand, Mike, Jorgen and I will be presenting the ACACIA results
>to a press \briefing on 1st November; and the same Q may well arise and we
>would then give the same response (since ACACIA is a an IPCC precursor).
>Correct?
>
>I think I am now clear about this, but I would like to be clearer about how
>far this is an IPCC position.
>Look forward to your replies,
>Martin
>
>Prof. Martin L. Parry
>Jackson Environment Institute
>University of East Anglia
>Norwich
>NR4 7TJ
>
>Tel: +44 (0) 1603 592 318
>Fax: +44 (0) 1603 593 896
>E-mail: parrymlatXYZxyz.com
>Web: [6]http://www.uea.ac.uk/env/jei
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Date: Fri, 26 Jan 2001 16:11:11 -0500
To: zkundze@man.poznan.pl, parrymlatXYZxyz.com
From: nlearyatXYZxyzcrp.gov (Neil Leary)
Subject: Abrupt change in THC simulated
Prof. Martin L. Parry
Jackson Environment Institute
University of East Anglia
Norwich
NR4 7TJ
Tel: +44 (0) 1603 592 318
Fax: +44 (0) 1603 593 896
E-mail: parrymlatXYZxyz.com
Web: [7]http://www.uea.ac.uk/env/jei

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