From: Michael Mann <mann@meteo.psu.edu>
To: Phil Jones <p.jones@uea.ac.uk>
Subject: Re: Past Millennia Climate Variability -  Review Paper
Date: Thu, 13 Mar 2008 08:58:49 -0400
Reply-to: mann@psu.edu

   Hi Phil,
   Sorry, one other point. In item #4 below, the point that is being made, as shown (and
   discussed) elsewhere, applies both to the MBH method and the the canonical regression
   method (the latter is demonstrated in experiments by Wahl and Ammann not shown but referred
   to elsewhere in the text).  So to be accurate and fair, the sentence in question on page 50
   really has to be rephrased as follows:
   Examinations of this kind are shown in Figures 3a,b (and  parallel experiments not shown)
   demonstrating that, at least for the truncated-EOF CFR method used by MBH98 (employing
   inverse regression) and the canonical regression method that has been widely used by many
   other paleoclimate researchers, there is some degree of sensitivity to the climatological
   information available in calibration.
   I realize there are many co-authors on the paper that have used the canonical regression
   method before, so perhaps there is pressure to focus the criticism on the MBH method. But
   that is simply not fair, as the other analyses by Wahl and Ammann not shown clearly
   demonstrates this applies to canonical regression as well--we can debate the relative
   sensitivity of the two methods, but it is similar.
   This is an absolutely essential issue from my point of view, and I'm afraid I cannot sign
   my name to this paper w/out this revision.
   I'm sure you understand--thanks for your help,
   mike
   Michael Mann wrote:

   Phil,
   Looks mostly fine to me now. I'm in Belgium (w/ the Louvain crowd) and only intermittent
   internet access, so will be difficult to provide much more feedback than the below. I hope
   that is ok? Here are my remaining minor comments:
   1) the author list is a bit front-loaded w/ CRU folks. You should certainly be the first
   author, but the remaining order makes this paper look more like a "CRU" effort than a
   "Wengen" effort, and perhaps that will have an unintended impact on the way the paper is
   received by the broader community. I was also wondering how I ended up so far down the list
   :(
   I think I was one of the first to provide a substantive contribution to the paper. Was my
   contribution really so minor compared to those others? The mechanism behind the author list
   is unclear, partially alphabetical (towards the end), but partly not. You are of course the
   best judge of peoples' relative contributions, and if the current author order indeed
   represents that according to your judgment, then I'm fine w/ that. Just thought I'd check
   though.
   2) page 45, 2nd paragraph, should substitute "(e.g. Shindell et al, 2001; Collins et al
   2002)" for "Collins et al 2002"
   3) page 48, 2nd paragraph, 3rd sentence, should substitute "RegEM (implemented with TTLS as
   described by Mann et al 2007)  for "RegEM".
   4) page 50, bottom paragraph, first sentence: I think that the use of "crucially" here is
   unnecessarily inflammatory and overly dramatic. This word can be removed without any
   detriment to the point being made, don't you think?
   5) page 51, 2nd paragraph, logic does not properly follow in certain places as currently
   phrased (a frequent problem w/ Eugene's writing unfortunately!):
   a. sentence beginning at end of line 9 of paragraph, should be rephrased as follows:
   Mann et al. (2005) used pseudo-proxy experiments that apparently showed that this method
   did not underestimate the amplitude of the reconstructed NH temperature anomalies: however,
   Smerdon and Kaplan (2007) show that this may have been a false positive result arising from
   differences between the implementation of the RegEM algorithm in the pseudo-proxy
   experiments and in the real-proxy reconstructions which leads to a sensitivity of the
   pseudoproxy results to the calibration period used (also noted by Lee et al., 2008).
   b. the sentence following the one above should be rephrased:
   Mann et al. (2007; cf. their Figs. 3-4) demonstrate that a variant of the RegEM method that
   uses TTLS, rather than ridge regression produces an NH temperature reconstruction whose
   amplitude fidelity does not exhibit the calibration interval dependence of the previous
   implementation by  Mann et al 2005, and yields reconstructions that do not suffer from
   amplitude loss for a wide range of signal-to-noise ratios and noise spectra (though Lee et
   al., 2008, suggest that an appropriately implemented ridge regression can also produce good
   results).
   c. the sentence following the one above should be rephrased:
   With TTLS as implemented by Mann et al (2007), RegEM performs without amplitude loss in
   model-based tests (versions without trend removal), including using the high-amplitude
   ECHO-G model output utilized by Bürger et al. (2006), von Storch et al. (2006), and Küttel
   et al. (2007) to examine truncated-EOF methods.
   6) page 52, 1st paragraph, 7th line, the reference ot "the MBH reconstruction" is
   erroneous, because the tests have nothing to do w/ the MBH reconstruction per se,
   only--potentially-the MBH method under certain circumstances. In fact, Mann et al (2007)
   [and Wahl and Amman(2007)] both show that the actual amplitude loss realized in the MBH
   reconstruction in reality is probably quite small. This very point is made at the top of
   page 53! So the reference to "the MBH reconstruction" needs to be eliminated here. It is
   already clear by context what this is actually referring to (idealized experiments using
   both the MBH and canonical applied to surrogate proxy networks).
   7) Re, Caspar--well he seems to be in his "non-responsible" phase right now, hasn't replied
   to my messages either. Will keep on trying,
   let me know if any of the above needs further elaboration. we're travelling for the weekend
   but will still have intermittent email access,
   mike
   Phil Jones wrote:

      Dear All,
          Attached is the penultimate draft of the Wengen paper. If you have time can you
     look
      through this. If you've not much time, can you look through your sections and
      the intro/conclusions. I hope we in CRU have got all your comments in. We have
      been through them all - including Gene's which came last night and Francis'
      the night before.
           WE URGENTLY NEED CASPAR TO REPOND. Can Gene, Mike and anyone
      who can get Caspar to respond to emails tell him that there are a few questions
      in this draft we need him to respond to. We need better versions of Figure 3, plus
      there are some flagged points in Sections 3 and 4.
         Juerg - is Figure 5 OK. If not resend separately - don't embed as this screwed up
     last time.
        Plan A is for us to submit this to The Holocene next Wednesday. So we need
      by then, from each of you a quick email to say you've got this and any comments
      by next Monday - March 17. Submission will be March 19. There is no Plan B.
        With the Feb 20 email, there were no responses from Peck, Eystein and Nick.
      If we don't hear from you three by next week, we will remove you from the author list!
      If anyone knows if any of these three are in the field please let me know?
      Things to check:
       1. Everybody happy with the author order. The idea here was the three us in CRU,
      the main authors of the sections in section order, then others in alphabetical order.
      2. If you have time also look at sections 2.5 and 2.6. Issue here is - is there enough
      there. Thanks to Juerg for some of these sections.
      3. There are a couple of refs (Juerg) we need - Buntgen et al. and D'Arrigo et al.
      Next week, we (CRU) will be working on the alterations- using IPCC rules.
      These are - if you want a change justify it, and if you say this is unbalanced, or
      just European, or emphasizes Lee et al. (2008), then gives us the additional text
      to make alterations. We've left a few comments in where these sorts of comments
      were made last time.
      There will be time to make alterations while The Holocene  reviews it. It will also
      be better to read it later when there is time after submission.
        I've not read this version yet, so apologies if there are any pieces of poor English.
      I will be reading again this weekend.
         Finally, Thorsten, if you think I've missed anybody off this email,
      forward and let me know.
         Juerg needs to send on to the others within Bern.
      Cheers
      Phil
     Prof. Phil Jones
     Climatic Research Unit        Telephone +44 (0) 1603 592090
     School of Environmental Sciences    Fax +44 (0) 1603 507784
     University of East Anglia
     Norwich                          Email    [1]p.jones@uea.ac.uk
     NR4 7TJ
     UK
     ----------------------------------------------------------------------------


--
Michael E. Mann
Associate 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:  [2]mann@psu.edu
University Park, PA 16802-5013

[3]http://www.met.psu.edu/dept/faculty/mann.htm


--
Michael E. Mann
Associate 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:  [4]mann@psu.edu
University Park, PA 16802-5013

[5]http://www.met.psu.edu/dept/faculty/mann.htm

References

   1. mailto:p.jones@uea.ac.uk
   2. mailto:mann@psu.edu
   3. http://www.met.psu.edu/dept/faculty/mann.htm
   4. mailto:mann@psu.edu
   5. http://www.met.psu.edu/dept/faculty/mann.htm

