Loehle’s introduction emphasized the absence of tree ring chronologies as being an important aspect of his network. I think that he’s placed too much emphasis on this issue as I’ll show below. I previously noted the substantial overlap between the Loehle network and the Moberg low-frequency network.
I thought that it would be an interesting exercise to consider Loehle’s network as a variation of the Moberg network as follows:
The results are shown in the Figure below. Obviously this method maintains the general “topography” of the Loehle network as to the medieval-modern relationship, while using a Team method (or at least a plausible emulation of the Moberg method.)
The difference between Moberg’s results (in which the modern warm period was a knife-edge warmer than medieval) and these results rests entirely with proxy selection. The 11 series in the Moberg low-freq network are increased to 18, primarily through the addition of ocean SST reconstructions (two Stott recons in the Pacific Warm Pool, Kim in the north Pacific, Calvo in the Norwegian Sea, de Menocal offshore Mauritania and Farmer in the Benguela upwelling, while excluding the uncalibrated Arabian Sea G Bulloides series – a proxy much criticized at CA). The other additions are the Mangini speleothem and the Holmgren speleothem (while the Lauritzen speleothem in Norway was excluded for reasons that I’m not clear about, but its re-insertion would not change things much) plus the Ge phenonology reconstruction and the Viau pollen reconstruction.
So the underlying issue accounting for the difference is not the inclusion or exclusion of tree ring series (in a Moberg style reconstruction) but mainly the inclusion of several new ocean SST and speleothem temperature reconstructions, combined with the removal of uncalibrated proxies.