From: "Mitchell, John FB \(Chief Scientist\)" <john.f.mitchell@metoffice.gov.uk>
To: "Stefan Rahmstorf" <rahmstorf@ozean-klima.de>, "Keith Briffa" <k.briffa@uea.ac.uk>
Subject: RE: Fwd: Re: [Wg1-ar4-ch06] NEW DRAFT FOR LA REVIEW
Date: Tue, 5 Sep 2006 12:29:08 +0100
Cc: "Eystein Jansen" <Eystein.Jansen@geo.uib.no>, "Jonathan Overpeck" <jto@u.arizona.edu>, "Jean Jouzel" <jouzel@dsm-mail.saclay.cea.fr>

   Keith, Stefan



   Its not my role as review editor to tell you what to write, just to make sure you have
   responded to the reviewers comments. For what its worth,
   I did find Keith's text quite involved.  However, you do need to respond the the reviewers
   comments on Burger etc - if the flaws in von Storch paper cast doubt on the subsequent
   papers, then why not include a sentence in the chapter that says so, and list just the key
   papers affected.

   I hope this helps

   john



   Professor John Mitchell OBE FRS Chief Scientist,
   Met Office FitzRoy Road  Exeter  EX1 3PB  United Kingdom
   Tel. +44(0)1392884604  Fax:+44 (0) 870 9005050
   E-mail: john.f.mitchell@metoffice.gov.uk [1]http://www.metoffice.gov.uk


     ______________________________________________________________________________________

   From: Stefan Rahmstorf [mailto:rahmstorf@ozean-klima.de]
   Sent: 01 September 2006 13:02
   To: Keith Briffa
   Cc: Mitchell, John FB (Chief Scientist); Eystein Jansen; Jonathan Overpeck
   Subject: Re: Fwd: Re: [Wg1-ar4-ch06] NEW DRAFT FOR LA REVIEW

   Dear Keith,
   you disagree with my proposed revision of the paragraph re. the Von Storch papers, but you
   do not give any reasons or arguments for that. I think there are some good reasons to
   shorten this discussion and to clarify it, and I would welcome to hear your reasons against
   it.
   Firstly, I think your original discussion was too long and complex to understand for
   non-specialists, and, at this level of detail, not policy-relevant. It took up a
   disproportionate amount of space for what we can learn from it.
   Secondly, I don't think we need to cite all those Storch-spinoff papers by Bürger/Cubasch.
   Most people whose judgement I value (e.g., David Ritson, who I think has no vested interest
   but a very detailed knowledge of the issue) think these papers are irrelevant at best and
   misleading at worst (he actually has used stronger wording). You may also have seen that
   the latest in this series, making similar points, is highly criticised by anonymous
   reviewers on the open discussion site of the journal Climate of the Past, where one
   reviewer (this is not the even more scathing review by Mann) recommends rejection of the
   Bürger/Cubasch paper because of "numerous errors and inaccuracies in the use of statistical
   concepts and methods".
   Third, if we cite Von Storch et al. 2004 we need to be very clear that a number of key
   statements are simply incorrect, which is a fact that is not in dispute and documented in
   the literature. They implemented the Mann et al. method incorrectly, and it is at least
   unclear whether in their follow-up paper they have now fixed this (Ritson, who discovered
   the problem in their original paper in the first place, thinks they still have a problem,
   the detrending step was not the only one - and certainly in no paper have VS et al. shown
   any test that verifies their algorithm). Also, they were hiding a major artificial climate
   drift (which they must have known about, and which makes up half of their climate signal) -
   it is at least unclear whether you can expect a proxy method based on physical patterns of
   climate variability to reconstruct an unphysical drift, which has a completely different
   pattern. I simply think that because of this flaw, we cannot trust or cite any results from
   this particular ECHO-G run, which also affects several of the Bürger/Cubasch papers using
   the same data set. Given that the VS04 paper was used in the US Senate and other
   high-profile fora to discredit IPCC, I think it is imperative that we clarify this and
   leave our readers in no doubt about the fact that the VS04 results have proven to be
   incorrect in a major way.
   I am aware that you authored a favorable Science Perspective on the VS04 paper at the time,
   but you could not have known of those errors back then, and for a long time I thought
   myself that it was a valid paper. Therefore, if we state clearly in our chapter what is
   wrong with it, I do not think this would be a loss of face for you - quite the contrary. I
   also think you have done a brilliant job on the rest of the very difficult discussion of
   the past millennium.
   Best wishes, Stefan
--
To reach me directly please use: [2]rahmstorf@ozean-klima.de
(My former addresses @pik-potsdam.de are read by my assistant Brigitta.)

Stefan Rahmstorf
[3]www.ozean-klima.de
[4]www.realclimate.org

References

   1. http://www.metoffice.gov.uk/
   2. mailto:rahmstorf@ozean-klima.de
   3. http://www.ozean-klima.de/
   4. http://www.realclimate.org/

