Wednesday, December 21, 2011


From: "Mitchell, John FB \(Chief Scientist\)" <>
To: "Stefan Rahmstorf" <>, "Keith Briffa" <>
Subject: RE: Fwd: Re: [Wg1-ar4-ch06] NEW DRAFT FOR LA REVIEW
Date: Tue, 5 Sep 2006 12:29:08 +0100
Cc: "Eystein Jansen" <>, "Jonathan Overpeck" <>, "Jean Jouzel" <>

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


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: [1]


From: Stefan Rahmstorf []
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
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 B�rger/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
B�rger/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 B�rger/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]
(My former addresses are read by my assistant Brigitta.)

Stefan Rahmstorf



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