From An Expert Lead Author: The Sordid IPCC History Of The 'Hockey Stick' Fabrication
(click on image to enlarge)
The adjacent image represents a temperature reconstruction from the Greenland ice sheet boreholes. The image was included in a peer reviewed paper that was published in 1998, which is approximately the same time the infamous 'hockey stick' graph was produced.
Although this paper confirmed the findings of a massive amount of previous research that the Medieval Warming generated higher temperatures than the current warming, the IPCC instead conferred star status to the statistically-tortured 'hockey stick' graph, which showed the previous warming to be less than the current era, and then was subsequently found to be without credible merit - a statistical travesty.
Why did the IPCC go with the unproven, statistical abomination that quickly smeared (irreparably?) the reputation of climate science?
"Christy’s assessment, when combined with the UEA emails, provides substantial insight into how this hockey stick travesty occurred. My main unanswered question is: How did Michael Mann become a Lead Author on the TAR? He received his Ph.D. in 1998, and presumably he was nominated or selected before the ink was dry on his Ph.D. It is my suspicion that the U.S. did not nominate Mann (why would they nominate someone for this chapter without a Ph.D.?)...Instead, I suspect that the IPCC Bureau selected Mann; it seems that someone (John Houghton?) was enamored of the hockey stick and wanted to see it featured prominently in the TAR."
Additional climate-history articles. The Michael Mann self-perpetuated, embarrassing "science" fiasco continues, as described here and here.