Mann's 'hockey stick' claims of the MWP and LIA being local were refuted years before it was published

Geologist Dr. Sebastian Lüning and Prof. Fritz Vahrenholt found a Japanese tree-ring temperature reconstruction from 1995, one that should have been heeded by the IPCC and Michael Mann before they took the world on a 10-year joyride in the stolen car of “climate science”.

Here’s the Google translation of their article, with some fixes of my own to help it along written in [brackets]. I don’t vouch for total accuracy in the translation, but it is the best I can do.

UPDATE: 2:45PM PST Pierre Gosselin has graciously agreed to allow his translation to be posted here, so I’m eliminating the Google translate version – Anthony

Medieval Warm Period and the Little Ice Age as a local, North Atlantic phenomenon: Since when is Japan located in the North Atlantic?

By Sebastian Lüning & Fritz Vahrenholt

(Translated and reposted here at WUWT with permission, copyright English text NoTricksZone)

Leading representatives of the IPCC tried for years to have policymakers and citizens believe the pre-industrial temperature history was more or less uneventful and was the ideal climate ondition that we should all strive to maintain. The warming of the 20th century, on the other hand, was completely unusual, something dangerous. However, as we now know, the page turned a few years ago and the notorious Hockey Stick chapter ended. The flawed curve was taken off the market and the Medieval Warm Period and Little Ice Age reappeared. 

As is often the case in history, it is in retrospect difficult to comprehend how this historical joyride could have happened to begin with. It started at the end of the 1990s with a doctoral thesis by Michael Mann, and did not end until about 10 years later – thanks to the discovery of the scientific scandal by Steve McIntyre and Ross McKitrick (see the book The Hockey Stick Illusion by Andrew Montford). Today it is difficult to fathom how the main players and proponents of the Hockey Sticks are still able to act as experts and public opinion shapers.

One of the main excuses used back then was that the Medieval Warm Period and Little Ice Age in Europe and North America were local phenomena. At other locations on the planet the temperature anomalies were more than evened out (e.g. Stefan Rahmstorf, Gerald Haug). For years we had to listen to their tales and we had to trust these “specialists” for better or for worse. Moreover, we paid them with our tax money so that they could deal exclusively with the climate and carry out the tedious work all this entails.

However, anyone who knew a little something about the scientific literature soon began to wonder. The Medieval Warm Period and the Little Ice Age as a local North Atlantic phenomenon? A nutty claim. Naturally these characteristic temperature fluctuations had been described for other parts of the world. Here we report on a case study from Japan which had appeared in the Geophysical Research Letters already in 1995, in other words, in the years before the Hockey Stick episode.

In the early 1990s, Japanese scientists Hiroyuki Kitagawa and Eiji Matsumoto extracted eleven tree ring cores from cedars on the South Pacific southern Japanese island of Yakushima. The cores contained tree-rings going back some 2000 years. The researchers determined the carbon 13 isotope values and found the delta-13-C values fluctuated in a characteristic manner (see Figure 1).

What did these fluctuations mean? Carbon-13 amount is influenced by a number of factors, among them temperature. The Japanese scientists calibrated the isotope development on trees of different elevations (and thereby temperature level) above sea level. Using this method they were able to come up with a formula that could be used for computing the temperature value using the isotope change. The results showed that temperatures over the previous 2000 years in South Japan fluctuated over a range of 5°C. The course of the temperature fluctuations takes on a shape that is very well known to us (see Figure 2). A clear millennium cycle is depicted. The cold period of the Migration Period, the Medieval Warm Period, the Little Ice Age and the Modern Warm Period are clearly recognisable. Moreover, this climate development is well documented in Japanese historical records.

Therefore, it is incomprehensible that with the clear Japanese data from the year 1995, the talk of a “local North Atlantic phenomenon” would go on for years after the data’s publication.

The two Japanese scientists even took it a step further. They carried out a detailed frequency analysis of their data and found characteristic cycles with periods in the range of several decades and centuries. Among others, they discovered a period of 187 years, which coincides with the known Suess/de Vries solar activity cycle. In a similar manner the 70 and 89-year Gleissberg-cycle was identified. In their results the authors saw a clear sign that the climate of the last 2000 years in southern Japan was predominantly influenced by solar activity fluctuations. The IPCC appears not to have been at all interested in the study. Indeed it did not fit with their climate catastrophe picture.

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NOTE: Commenter Peter Gulutzam made this observation in comments. The original Google translation correctly noted “…the southern Japanese island of Yakushima…” but Gosselin’s version incorrectly identifies it as a South Pacific Island. I’ve made the correction and notified Mr. Gosselin – Anthony