In 2000, Keith Briffa, lead author of the millennial section of AR4, published his own versions of Yamal, Taymir and Tornetrask, all three of which have been staples of all subsequent supposedly “independent” reconstructions. The Briffa version of Yamal has a very pronounced HS and is critical in the modern-medieval differences in several studies. However, the Briffa version for Yamal differs substantially from the version in the publication by the originating authors (Hantemirov, Holocene 2002), but is the one that is used in the multiproxy studies (though it’s hard to tell since Hantemirov is usually cited.) Studies listed in AR4 that use the Briffa versions include not just Briffa 2000, but Mann and Jones 2003, Moberg et al 2005, D’Arrigo et al 2006, Hegerl et al 2007, as well as Osborn and Briffa 2006.
Of the 8 proxies shown in the proxy spaghetti graph (as opposed to the reconstruction spaghetti graph), 3 are from the Briffa 2000 study (called NW Russia, N Russia and N Sweden) but demonstrably the Briffa versions of these sites.
An important characteristic of tree ring chronologies is that they are sensitive to the method used. Chronologies can be quickly and easily calculated from measurement data. Rob Wilson, for example, will nearly always run his own chronologies from measurement data so that he knows for sure how they were done and so that they are done consistently across sites.
Osborn and Briffa 2006 was published in Science, which has a policy requiring the availability of data. It used Briffa’s versions of Yamal, Taymir and Tornetrask. At the time, I requested the measurement data, which had still not been archived 6 years after the original publication of Briffa 2000, despite the availability of excellent international archive facilities at WDCP-A (www.ncdc.noaa.gov/paleo). Briffa refused. I asked Science to require Briffa to provide the data. After some deliberation, they stated that Osborn and Briffa 2006 had not used the measurement data directly but had only used the chronologies from an earlier study and that I should take up the matter with the author of the earlier study, pointedly not identifying the author, who was, of course, Briffa himself. I wrote Briffa again, this time in his capacity as author of the 2000 article in Quaternary Science Reviews and was blown off. (See here for my last account of efforts to get Briffa data via Science mag.)
So years later, the measurement data for key studies used in both canonical multiproxy studies and illustrated in AR4 Box 6.4 Figure 1 (along, remarkably, with Mann’s PC1), remains unarchived, with Briffa resolutely stonewalling efforts to have him archive the data.
But has Briffa, after all these years, finally made a misstep? Continue reading






