Friday, June 15, 2012


date: Wed Oct 18 18:44:53 2000
from: Mike Hulme <>
subject: Re: THC Europe

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 [1][2]htm .
At 12:38 18/10/00 -0400, 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
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).
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,
Prof. Martin L. Parry
Jackson Environment Institute
University of East Anglia
Tel: +44 (0) 1603 592 318
Fax: +44 (0) 1603 593 896
Web: [3]

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