Peer-Reviewed Research: Unprecedented Global Warming During Medieval Period, Boreholes Reveal

C3
"Way back in 1997, researchers published a paper that was based on data from 6,000 plus borehole sites from all the continents. The reconstructed temperatures clearly showed a Medieval Period warming that was, and is, unprecedented. The data also makes clear that subsequent warming began well before the growth of human CO2 emissions and this natural rebound would obviously lead to temperatures similar to the Medieval Period.

A year later, the infamous Mann hockey-stick temperature chart was published to wild acclaim by the IPCC and AGW-centric activists. So popular did the Mann chart become, the 6,000+ borehole chart was completely ignored since its data refuted the Mann study. The borehole scientists then decided to re-publish their study with primarily only the blue-side (the typical AGW-favored data cherry-picking) of the chart below. This repackaged borehole study became accepted by the AGW-centric scientists as it seemed to support their cause and the Mann's hockey-stick."

H/T Climate Depot