From	Stefan Rahmstorf	Date	Tue, 28 Feb 2006 18:32:25 +0100
To	Tim Osborn
CC	Keith Briffa, Jonathan T. Overpeck, Eystein Jansen, Fortunat Joos, David Rind
Subject	Re: latest draft of 2000-year section text
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: [1]rahmstorf@ozean-klima.de (My former addresses @pik-potsdam.de are read by my assistant Brigitta.) Stefan Rahmstorf [2]www.ozean-klima.de [3]www.realclimate.org References 1. mailto:rahmstorf@ozean-klima.de 2. http://www.ozean-klima.de/ 3. http://www.realclimate.org/