from: Linda Mearns <lindamatXYZxyz.ucar.edu>
subject: Comments on Draft TGCIA Report
COMMENTS ON DRAFT TGCIA REPORT, received June 9, 1998.
Any sections for which I have no specific comments are ones that
I largely agree with.
Under 2.1 OUTPUTS --
I assume that whether the guidance material is to be a reviewed IPCC document will be
discussed at the scoping meeting?
I like Filippo's idea of dividing the guidance material into two parts.
(And with which it appears TIm also agrees).
However, I think all this must be considered in light of what we do about a
Scenarios Chapter in WGI and WGII.
a. Inventory of Air-Ocean GCMs - Air should be changed to Atmosphere
b. In principle, yes WGI TSU could handle this, but I think good coordination with
WG II would be essential -- the point of making this inventory is the
use of the regional models for climate change scenarios development --
in this regard it really is the purview of both WG's.
I repeat here a comment I have made several times now, that has not been addressed.
It's fine not to address it now, but I'd like to know if we will ever address it
or will the whole idea be dropped?
This is a comment I included in response to agenda items:
Point 3.1c, however, is incomplete. As I indicated to Richard Moss
a few weeks ago, M. Noguer, L. Mearns, and F. Giorgi were charged with
coming up with a plan for doing some intercomparisons of regional
models. I have gone ahead and discussed some possible plans with
some of the major regional modelers in the world. This has included
Renee LaPrise, Machenauer, John McGregor. I need to contact Richard
Jones as well. What I disussed was doing an intercomparison of
regional model responses to the same external forcings in the same
region. A preliminary region and possible nesting GCMs have been
discussed. We should either go forward to firm up these plans, or
abandon them. I have found the regional modelers quite willing to
Under 2.2 RECOMMENDATIONS
a) I LIKE THE OPENING STATEMENT, but I feel we should make a
STATEMENT regarding how this recognition is to be expressed.
I think we should explicitly recommend a chapter
or chapters on climate change scenario development, and EMPHASIZE
ITS (THEIR) ROLE IN UNIFYING WG I and II WORK.
I feel this is still leaving the details to the scoping meeting,
as seemed to be the general will of TGCIAers, but makes a stronger
statement in the report.
Of course you, Martin and Richard, know a great deal more about
the politics of IPCC than I do. My reasoning is based on the simple
principle of asking for 100%.
I fear if we don't make a strong statement in the report, it will
be easier to whittle the scenarios down to a sub section of another
I really don't think it makes much sense to have it as part of a regional
b) Regions -- I'm not sure the second statement is very meaningful, since
it seems very unlikely that there would be time now to develop
regional scenarios for TAR, depending on what you mean by regional
scenarios -- I assume this has to mean some form of higher
resolution scenario (either downscaling or regional modeling).
The statement as it stands is pretty bland, but
I agree that we should say something.
But we can't we say a little more here?
Perhaps at least make a statement to recommend regional intercomparisons
of downscaling techniques? I believe we did go so far as to
encourage comparative studies (see my point above in 2.1 III.b).
3. REMAINING WORK
Yes, I think work on REGIONAL SCENARIOS could become a major task for the
TGCIA for the next two years. I assume we don't have to become
extremely detailed about the task at this point. This could
entail recommending further comparisons, or perhaps revisiting
selection of scenarios, depending on how this discussion goes in
the scoping meeting.
An additional area could be in the ANNOTATION OF CLIMATE CHANGE SCENARIOS --
i.e., work in trying to determine the effect of errors in climate model control
runs on the scenarios produced. I think this would be a good task for
further unifying WG I and WG II activities.
Dr. Linda O. Mearns Phone: 303 497 8124
Scientist Fax: 303 497 8125
Environmental and Societal Impacts Group e-mail: lindamatXYZxyzr.edu
NCAR P.O. Box 3000
Boulder, CO 80307