The infamous "Hockey Stick" graph was featured prominently in the IPCC TAR Summary for Policymakers. It was important in that it overturned the concept of a global Medieval Warm Period warmer than the 20th century and a global Little Ice Age,……………………….
................... This caused quite an uproar in the sceptic community, not least because of its visual efficacy. Two Canadians, an economist and a petroleum geologist, took it upon themselves to verify this…………
………………. The Canadians, McIntyre and McKitrick, then proceeded to publish a paper that purported to uncover serious methodological flaws and some problems with data sets used……………
…………………. To my knowledge, the worst indictment (of M & M’s view – my, clippo, clarification) from the climate science community came from a study led by Hans Von Storch that concluded M&M was right about a particular criticism of methodology but correcting it did not in fact change the study results...............
...........The fact is there are dozens of other reconstructions. These other reconstructions do tend to show some more variability than MBH98 (the handle of the hockey stick is not as straight), but they all support the general conclusions that the IPCC TAR presented in 2001: the late 20th century warming is anomalous in the last one or two thousand years and the 1990's are very likely warmer than any other time in the last one or two thousand years. …………………………..
……………I suspect 95% of the people you will come across arguing about this have chosen their position ideologically and will not really be able to explain the merits of the various arguments. …………………….
……………….So while MBH, in my mind, are in no way guilty of fraud or incompetence (many of the accusations do go this far), the judgement of their research must be approached in reverse: …………..
………………… So where does that leave me and I suspect most of you?
Well, it leaves me with the dozens of other proxy reconstructions, some by the same team or involving some of its members, some by completely different people, some using tree rings, some using corals, some using stalagmites, some using borehole measurements, but all of which support the same general conclusion.
The general conclusion is:
"Although each of the temperature reconstructions are different (due to differing calibration methods and data used), they all show some similar patterns of temperature change over the last several centuries. Most striking is the fact that each record reveals that the 20th century is the warmest of the entire record, and that warming was most dramatic after 1920."
End of story.
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