cc: zkundze@man.poznan.pl date: Wed Oct 18 18:44:53 2000 from: Mike Hulme subject: Re: THC Europe to: PARRYML@aol.com, tim.carter@vyh.fi 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]http://www.nerc.ac.uk/ms/THC/index.[2]htm . Mike At 12:38 18/10/00 -0400, PARRYML@aol.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: parryml@aol.com Web: [3]http://www.uea.ac.uk/env/jei