From: Michael Mann <mann@meteo.psu.edu>
To: Tom Wigley <wigley@ucar.edu>
Subject: Re: help
Date: Tue, 22 Sep 2009 11:00:28 -0400
Cc: Phil Jones <p.jones@uea.ac.uk>, Caspar Ammann <ammann@ucar.edu>

   Hey Tom, thanks for checking w/ me on this. Re, Moberg: Yes, in fact we (me, Phil, Tim,
   Keith, Caspar, etc.) submitted a comment to Nature about the problem w/ the variance
   scaling used by Moberg. It can easily be shown to inflate the low- frequency variance in
   synthetic experiments. I've attached both the original comment (which they judged to be too
   technical to merit publication) and also a J. Climate paper where we discussed the same
   result (see Figure 5 and associated discussion). Re, Von Storch et al. Yes, the paper you
   have in mind is Osborn et al Climate Dynamics '06. I only seem to have the preprint though
   (attached), please let me know if I can be of any further help w/ an of this, mike p.s. you
   can delete the U.Va email address--haven't been there for 4 years! On Sep 22, 2009, at
   10:31 AM, Tom Wigley wrote: > Dear all, > > (Apologies Mike for email address confusion --
   one of them will > get you I hope.) > > I need some help to finish a report I've had to
   write for EPRI -- > which is due in a few days. Hence the questions below ... > > (1) The
   Moberg paper (2005 Nature) is used by the skeptics as evidence > that most of recent
   warming could still be natural. Has anyone > published a critique/criticism of this? It
   seems to me take this > work is fundamentally flawed. First, variance scaling is crap >
   statistics as it produces results with far less explained variance > than normal
   least-squares regression. Second, the paper seems to > have no independent validation.
   Third, what happens if one just takes > his low-frequency (numbered in his Fig. 1) points
   and calculates > the area average? Surely this will have much greater variability > than
   the full global mean? (If no-one has done this please let me > know -- I can do it very
   easily myself.) But perhaps his scaling > method circumvents this "problem"? > > (2) What
   is the paper of Caspar's (with Doug Nychka) that shows > that McIntyre is wrong? Are there
   other papers I should see/cite > in this regard? > > (3) What are the papers that explain
   what is wrong with the von > Storch ECHO simulation? I think Tim Osborn did something on
   this. > > Many thanks for your help, > Tom. > -- Michael E. Mann Professor Director, Earth
   System Science Center (ESSC) Department of Meteorology Phone: (814) 863-4075 503 Walker
   Building FAX: (814) 865-3663 The Pennsylvania State University email: mann@psu.edu
   University Park, PA 16802-5013 website: http://www.meteo.psu.edu/~mann/Mann/index.html
   "Dire Predictions" book site:
   http://www.essc.psu.edu/essc_web/news/DirePredictions/index.html Hey Tom,

   thanks for checking w/ me on this.

   Re, Moberg: Yes, in fact we (me, Phil, Tim, Keith, Caspar, etc.) submitted a comment to
   Nature about the problem w/ the variance scaling used by Moberg. It can easily be shown to
   inflate the low-frequency variance in synthetic experiments.

   I've attached both the original  comment (which they judged to be too technical to merit
   publication) and also a J. Climate paper where we discussed the same result (see Figure 5
   and associated discussion).

   Re, Von Storch et al. Yes, the paper you have in mind is Osborn et al Climate Dynamics '06.
   I only seem to have the preprint though (attached),

   please let me know if I can be of any further help w/ an of this,

   mike

   p.s. you can delete the U.Va email address--haven't been there for 4 years!

   On Sep 22, 2009, at 10:31 AM, Tom Wigley wrote:

   Dear all,
   (Apologies Mike for email address confusion -- one of them will
   get you I hope.)
   I need some help to finish a report I've had to write for EPRI --
   which is due in a few days. Hence the questions below ...
   (1) The Moberg paper (2005 Nature) is used by the skeptics as evidence
   that most of recent warming could still be natural. Has anyone
   published a critique/criticism of this? It seems to me take this
   work is fundamentally flawed. First, variance scaling is crap
   statistics as it produces results with far less explained variance
   than normal least-squares regression. Second, the paper seems to
   have no independent validation. Third, what happens if one just takes
   his low-frequency (numbered in his Fig. 1) points and calculates
   the area average? Surely this will have much greater variability
   than the full global mean? (If no-one has done this please let me
   know -- I can do it very easily myself.) But perhaps his scaling
   method circumvents this "problem"?
   (2) What is the paper of Caspar's (with Doug Nychka) that shows
   that McIntyre is wrong? Are there other papers I should see/cite
   in this regard?
   (3) What are the papers that explain what is wrong with the von
   Storch ECHO simulation? I think Tim Osborn did something on this.
   Many thanks for your help,
   Tom.

   --
   Michael E. Mann
   Professor
   Director, Earth System Science Center (ESSC)
   Department of Meteorology                 Phone: (814) 863-4075
   503 Walker Building                              FAX:   (814) 865-3663
   The Pennsylvania State University     email:  [1]mann@psu.edu
   University Park, PA 16802-5013
   website: [2]http://www.meteo.psu.edu/~mann/Mann/index.html
   "Dire Predictions" book site:
   [3]http://www.essc.psu.edu/essc_web/news/DirePredictions/index.html

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   "c:\eudora\attach\osbornetalClimDynInPress06.pdf"

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