A Review of Temperature Reconstructions

By Andy May

In previous posts (here and here), I’ve compared historical events to the Alley and Kobashi
GISP2 Central Greenland Temperature reconstructions for the past 4,000 years. Unfortunately, these two reconstructions are very different. Recently Steve McIntyre has suggested a third reconstruction by Bo Vinther. Vinther’s data can be found here. Unfortunately, Vinther is often significantly different from the other two. The Alley data has been smoothed, but the details of the smoothing algorithm are unknown. So the other datasets have been smoothed so they visually have the same resolution as the Alley dataset. Both datasets (Kobashi and Vinther) were first smoothed with a 100 year moving average filter. Then 20 year averages of the smoothed data were taken from the one year Kobashi dataset to match the Vinther 20 year samples. The Alley data is irregularly sampled, but I manually averaged 20 year averages where the data existed. If a gap greater than 20 years was found that sample was skipped (given a null value).

All three reconstructions are shown in Figure 1. There is no reason to prefer one of the three reconstructions over the other two, so I simply averaged them. The average is the blue line. I’m not presenting this average as a new or better reconstruction, it is merely a vehicle for comparing the three reconstructions to one another and to other temperature reconstructions. This is an attempt to display the variability in common temperature reconstructions for the past 2,000 to 4,000 years.

Figure 1

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#average-global-temperature, #global-circulation-models, #hide-the-decline, #ipcc, #mikes-nature-trick

New Book: A Disgrace to the Profession, by Mark Steyn

Mark Steyn has written a wonderful new book on Dr. Michael Mann’s hockey stick and the controversy surrounding it. It is difficult to overstate the significance or impact of Mann’s Hockey Stick (Mann, Bradley, Hughes (23 April 1998), “Global-scale temperature patterns and climate forcing over the past six centuries” (PDF), Nature 392 (6678): 779–787, Figure 5, the paper is often abbreviated as “MBH”). The Hockey Stick appeared in Figure 1 of the Summary for Policymakers of the third IPCC Assessment Report (called “TAR” published in 2001) and it was prominently displayed in Al Gore’s movie “An Inconvenient Truth.” As the book clearly shows, both the graph and the movie have been thoroughly discredited by hundreds of scientists who have attempted and failed to reproduce Michael Mann’s hockey stick using his data and other proxy data.

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#a-disgrace-to-the-profession, #climate-change, #hide-the-decline, #hockey-stick, #ipcc, #mark-steyn, #mikes-nature-trick, #scientific-fraud