As you can see from the plot of the Juckes’ proxies, the Yang composite is a very important contributor to the 20th century blade. The Yang Composite is a mainstay of recent Hockey Team reconstructions – its use in Team reconstructions began in Mann and Jones 2003 and was then “randomly selected” into Osborn and Briffa 2006, Hegerl et al 2006 and now Juckes et al 2006.
The two series in the Yang composite that drive its 20th century blade are versions of two Thompson series from Dunde and Guliya. The Juckes “evaluation” did not evaluate the data versions. I’ve posted up on Dunde before, pointing out inconsistencies between the different versions (the Yang version has values only at 50 -year intervals!) Today I checked out the Guliya version. In addition to the Yang version (emailed to me by Dr Yang a couple of years ago), Thompson archived the version used in his Climatic Change 2004 article (only after my intervention) and has just archived a new version in connection with his PNAS 2006 article. The three versions are plotted below – the first 2 are at 10-year resolution; the last one at 5-year resolution:
Figure 1. Three versions of Thompson’s Guliya dO18 ice core series.
There is obviously a strong visual inconsistency between the different versions. This is reflected in the correlations. The correlation between the Yang version and the Climatic Change version is only 0.06. Remarkably, the correlation between the PNAS version (converted to 10-year intervals) and the Climatic Change version from only 2 years ago is -0.005. The data was collected nearly 15 years ago.
I’ve written to Science repeatedly asking them to require Thompson to archive and reconcile these conflicting results, but have been blown off completely.
Should Juckes have evaluated the conflicting versions of Thompson data used in the Yang composite? I think so.