Science has published a Correction and Clarification to Kaufman et al (2009), see here. Since they only needed to correct four out of 23 proxies, there is no need to name those who pointed out errors. There is a small improvement over the draft version though; congratulations Hu!
We thank H. McCulloch and others who have pointed out errors and have offered suggestions.
Related News: Prof. Matti Saarnisto was in a discussion program (A-talk) on Finnish National TV (YLE TV1) on Thursday. My translation (and transcription!) of parts that may be of general interest here. [19:54-22:05]
Sari Huovinen (journalist): Matti, your own research result has been distorted in public. Tell us shortly, what was done.
Matti Saarnisto: Well, indeed, here … one of the persons who have been [lately] in public, professor Mann from The Pennsylvania State University. He has published several articles about the climate history of past thousand years. The last time it was last the history of last two thousand years [published] with many colleagues. In that [article], research material, from Korttajärvi near Jyväskylä, of my group was used such that the Medieval Warm Period was show as a mirror image.
SH: That is, the graph was flipped?
MS: The graph was flipped upside-down. And, and, … it was in Science in last August, and, …
SH: Why was that done, how do you interpret that?
MS: That is something I’ve tried to sort out … in this e-mail I received yesterday from one of the authors of the article, from my good friend prof. Ray Bradley in Chile, where he was traveling. There was a large group of researchers who had been handling an extremely large research material, and at some point it had happened such that this graph had been turned upside-down.
SH: So it was not done in purpose, it was a mistake?
MS: Well, when Bradley says so to me, I don’t doubt even a slightest moment. I hold him in high regard. He is one of the best paleoclimate researchers, and … a frequent visitor in Finland. But then that this happened yet another time in Science … in Apr… in November last year, a little before Christmas … again this Korttajärvi material, which was a part of Mia Tiljander’s PhD Thesis, Mia Tiljander is a known person worldwide, and … the article where the material appeared was published in 2003. Mia Tiljander was the first author, I was the second, and good, younger collogues of mine, Timo Saarinen and Antti Ojala, were then after…
SH: … yes …
MS: It has been turned twice upside-down in Science, and now I doubt if it can be a mistake anymore.
I’d like to point out to prof. Saarnisto that Michael Mann was not a coauthor in Kaufman et al. (2009). In fact, the only person who has been one of the authors in every three studies using upside-down Tiljander series is Raymond s. Bradley.
Later in the program (24:35-25:22) we have more.
MS: This group, who has now been in negative light in public, I know them and I have discussed with them, it has been slightly hard for them over the years … They have been somehow skeptical about this Medieval Warm Period and have tried to hide it to some extent. I have always thought that this was purely a case of scientific critique, but now in the last few days I have come somewhat to a conclusion that there is some purposefulness in this.
SH: That is, one is aiming at a truth?
MS: Yes, but how it is possible that this type of material is repeatedly published in these top science journals … it is because of the peer review process central to science. There is a small circle going around ["piiri pieni pyörii" (*)], relatively few people are reviewing each others papers and that is in my opinion the worrying aspect.