Friday, May 18, 2012


date: Mon, 21 Aug 2000 10:19:17 -0400
subject: Re: Tables on extremes
to: Timothy Carter <>


Thanks for the update -- I don't know where you would include extremes such
as hail frequency or tornadoes in your table --- these are not quite the
same as tropical cyclones where you have winds, rain, waves, etc.

Other than that it looks very informative.


Timothy Carter <> on 08/21/2000 08:28:11 AM

Tom Karl/NCDC,,,,,


Subject: Tables on extremes

To: Barrie Pittock (Ch 3/WG II - Maureen at ECI: Please pass this on to
Linda Mearns (Ch 10+13/WG I; Ch 3/WG II)
Mike Hulme (Ch 10+13/WG I)
Steve Schneider (Ch 1/WG II)
Peter Whetton (Ch 10+13/WG I)
Tom Karl (Ch 2/WG I)
Chris Folland (Ch 2/WG I)
Filippo Giorgi (Ch 10/WG I)
Bruce Hewitson (Ch 10/WG I)
Jerry Meehl (Ch 9/WG I)
Ulrich Cubasch (Ch 9/WG I)
Thomas Stocker (Ch 7/WG I)

Dear colleagues,

Some of you will be already be aware that Working Group II are in the
process of constructing a (revised) table of extreme climatic phenomena
based on WG I information. The Table is designed to portray globally
generalised information on anticipated future changes in extremes as well
as observed evidence for qualitatively similar changes in the instrumental
record. We are using a typology of extremes described in Chapter 1/WG II
(This is Steve Schneider's chapter, and I am attaching a marked up version
of this table, tab1-1#2.doc, for Steve's comment following our Lisbon
discussion and to inform other colleagues of our threefold classification
of extremes).

Jerry Meehl recently circulated a draft Table with some of this extremes
information summarised for Chapter 9, using the WG I confidence scale
agreed in Victoria. Some of you may have already sent Jerry comments on
this Table.

The Working Group II Table (in Chapter 3) used inputs from WG I following
discussion among a few of us at a side meeting in Auckland on extremes
(e.g. Tom Karl contributed some confidence measures for observed changes).

At the WG II meeting in Lisbon 2 weeks ago we revised this Table using new
information from the draft Meehl et al. Chapter 9 Table. Our revised Table
was circulated to the WG II authors and generated much discussion.

In particular, WG II authors are very uncomfortable with the WG I
confidence scale and we were strongly recommended to use the Schneider and
Moss 5 point scale, which has been adopted by WG II.

We have also included information on Tropical Cyclones based on the Ch 10

Furthermore, we have added two "singular" phenomena (THC cessation and WAIS
collapse), though these do not appear with confidence levels attached in
Jerry's Table or elsewhere in WG I. They are of importance for impacts and
we would like to include them.

On the basis of the discussion in Lisbon, I have redrafted the Table once
again and am circulating it among the listed persons for comment
(tab3-9#4.doc). Your suggestions would be much appreciated as this Table
may well find its way into the TS and maybe even the SPM of WG II, because
it is of obvious relevance to impacts work.

I would appreciate your comments and suggestions by 31 AUGUST (latest) so
that I can make any necessary revisions before distributing this to the WG
II authors.

Finally ........

To Jerry, Ulrich and Thomas: Ch 9 has a statement on the THC slowdown in
AOGCMs that is repeated in the SPM and has been repeatedly cited by the
Global Climate Coalition, Saudi Arabia and some others who have read this
through VERY CAREFULLY, to question the validity of any WG II exploratory
impact assessments that relate to a possible cooling over Europe.

"Most models show weakening of the thermohaline circulation (THC), which
contributes to a reduction of the warming in the North Atlantic regions.
Even in models, where the THC weakens, there is still a warming over Europe
to to increased greenhouse gases."

However, there is apparently no statement on the likelihood of an abrupt
COLLAPSE of the THC, though this has been modelled by intermediate
complexity models and is reported in some detail in Ch 7/WG I, though not
in the Ch 7 ES except in very vague terms (Thomas?). It is also explored in
some detail in Chapter 19/WG II (Synthesis). I wonder if this "not
impossible" scenario, which would mean large scale disruption of the
climate over the North Atlantic region (probably including significant
cooling) and is hence a low probability but high impact event, should be
accorded some qualitative confidence rating too somewhere in WG I, to
counterbalance the somewhat "optimistic" Ch 9 conclusion?

Any assistance (by 31 August!) would be much appreciated.

Best regards,

Tim Carter (Ch 3/WG II; Ch 13/WG I)

Attachment Converted: "c:\eudora\attach\tab1-1#21.doc"

Attachment Converted: "c:\eudora\attach\tab3-9#41.doc"


Dr. Timothy Carter
Finnish Environment Institute
Box 140, Kes
�katu 6, FIN-00251 Helsinki, FINLAND

Tel: +358-9-40300-315; GSM +358-40-740-5403
Fax: +358-9-40300-390


No comments:

Post a Comment