Thursday, May 17, 2012

4351.txt

cc: Keith Briffa <k.briffaatXYZxyz.ac.uk>, jto@u.arizona.edu, eystein.jansen@geo.uib.no, Fortunat Joos <joosatXYZxyzmate.unibe.ch>, drind@giss.nasa.gov, rahmstorfatXYZxyzan-klima.de
date: Wed, 1 Mar 2006 09:07:28 -0700
from: Jonathan Overpeck <jtoatXYZxyzrizona.edu>
subject: Re: latest draft of 2000-year section text
to: Tim Osborn <t.osbornatXYZxyz.ac.uk>

<x-flowed>
All - yes, it's great that the Wahl et al papers (both in Science,
and in CChange) were accepted this week. These both help clarify the
issues.

Thanks, peck

>Hi again Stefan,
>
>I'm sympathetic to many of these points that you make. Obviously
>only the scientific literature can be covered in the chapter, rather
>than the interpretation or testimony that appeared elsewhere. Given
>that the bias appears real, though of unknown magnitude, I think we
>should include a citation to the new comment (Wahl et al.) along
>with the existing citations that are given at the end of the
>existing text that states that the extent of the bias is uncertain.
>
>Cheers
>
>Tim
>
>At 17:32 28/02/2006, Stefan Rahmstorf wrote:
>>Hi Tim,
>>
>>my simplistic interpretation as an outside observer of this field is:
>>
>>VS04 published a high-profile analysis in Science concluding that
>>the performance of the MBH method is disastrously bad.
>>Subsequently, VS in the media called the MBH result "nonsense",
>>accused Nature of putting their sales interests above peer review
>>when publishing MBH, and called the IPCC "stupid" and
>>"irresponsible" for highlighting the results of MBH. This had
>>*major* political impact - I know this e.g. from EU negotiators who
>>were confronted with this stuff by their US colleagues.
>>
>>Then it turns out that they implemented the method incorrectly. If
>>it is done as MBH did, variance is still somewhat underestimated in
>>the same pseudoproxy test, but only a little, within the error bars
>>given by MBH and shown by IPCC. Certainly nothing dramatic - one
>>could conclude that the method works reasonably well but needs
>>improvement. This would have been a technical discussion with not
>>much political impact.
>>
>>What VS and their colleagues are doing now, rather than publishing
>>a correction of their mistake, is saying: "well, but if we add a
>>lot more noise, or use red noise, then the MBH method is still
>>quite bad..."
>>
>>The question here is: should our IPCC chapter say something to
>>correct the wrong impression which had the political impact, namely
>>that the MBH method is disastrously bad? This is not the same as
>>the legitimate discussion about the real errors in proxy
>>reconstructions, which accepts that these reconstructions have some
>>errors but are still quite useful, rather than being "nonsense".
>>
>>Cheers, Stefan
>>
>>--
>>To reach me directly please use:
>><mailto:rahmstorf@ozean-klima.de>rahmstorf@ozean-klima.de
>>(My former addresses @pik-potsdam.de are read by my assistant Brigitta.)
>>
>>Stefan Rahmstorf
>><http://www.ozean-klima.de>www.ozean-klima.de
>>www.realclimate.org
>
>Dr Timothy J Osborn
>Climatic Research Unit
>School of Environmental Sciences, University of East Anglia
>Norwich NR4 7TJ, UK
>
>e-mail: t.osbornatXYZxyz.ac.uk
>phone: +44 1603 592089
>fax: +44 1603 507784
>web: http://www.cru.uea.ac.uk/~timo/
>sunclock: http://www.cru.uea.ac.uk/~timo/sunclock.htm


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

Mail and Fedex Address:

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