cc: Eystein Jansen <eystein.jansen@geo.uib.no>
date: Wed, 1 Mar 2006 09:11:15 -0700
from: Jonathan Overpeck <jto@u.arizona.edu>
subject: Fwd: Re: latest draft of 2000-year section text
to: Keith Briffa <k.briffa@uea.ac.uk>, TBaumgar@CICESE.MX, TRBaumgartner@UCSD.Edu

   Just to you - seems you could go a little further and be more clear as Stefan suggests. Not
   a major change. Your call, though. Thanks, Peck

     X-Sieve: CMU Sieve 2.2
     Date: Wed, 01 Mar 2006 15:55:41 +0100
     From: Stefan Rahmstorf <rahmstorf@ozean-klima.de>
     X-Accept-Language: en-us, en
     To: Fortunat Joos <joos@climate.unibe.ch>
     Cc: Jonathan Overpeck <jto@u.arizona.edu>,
          Tim Osborn <t.osborn@uea.ac.uk>, Keith Briffa <k.briffa@uea.ac.uk>,
          cddhr@giss.nasa.gov, Eystein Jansen <eystein.jansen@geo.uib.no>
     Subject: Re: latest draft of 2000-year section text
     X-Provags-ID: kundenserver.de abuse@kundenserver.de
     login:a55186a74a9492274b66220889845b72

     Hi all,
     let me add to Fortunat that I feel Keith and Tim have done a tremendous job in very
     thorny terrain. And I agree with Peck - science has moved way past the "hockey stick"
     debate, and it is great how our chapter shows that.
     Nevertheless, we should remember that the Von Storch et al. (2004) critique was a
     fundamental methodological critique that applies to *all* (or at least most) proxy
     reconstructions - it is not just a Storch vs. Mann quarrel (although it is that as well,
     of course). Hence it is worth mentioning their error, else this could still call the
     entirety of our conclusions from that section into question.
     Currently, our draft just says:

     At present, the extent of any such bias in specific reconstructions is uncertain

     This is true, but leaves in my view slightly too much room for interpretation - like, it
     would still encompass the interpretation that the bias of all reconstructions is
     desastrous, so they are all "nonsense" in Von Storch's words.
     What about saying something along the lines:
     "At present, the extent of any such bias in specific reconstructions is uncertain,
     although probably not as large as suggested by Von Storch et al. (2004), whose work was
     affected by a calibration error (Wahl, Ritson and Amman, 2006)."
     Regards, Stefan
     p.s. Tim: Are you convinced the more recent papers by the VS group use the correct
     calibration? In those curves that are intended to show the pseudoproxies perform poorly
     even when calibrated correctly, as long as you add a lot more noise, I wonder why the
     pseudoproxies perform poorly even within the calibration interval, where they now should
     be calibrated to properly reproduce the 20th C warming trend, and they don't?

--

   Jonathan T. Overpeck
   Director, Institute for the Study of Planet Earth
   Professor, Department of Geosciences
   Professor, Department of Atmospheric Sciences
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