UPDATE3: professor Rob Wilson leaves some scathing comments about the Mann paper. See below.

UPDATE2: There’s been some additional discussion on the dendro listserver, and it seems quite clear now that the scientists in the dendrochronology field don’t think much of Dr. Mann’s effort – and it appears there is a rift now between former co-authors. See the must read below. I’ll make this a sticky for about a day, and new posts will appear below this one. – Anthony

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People send me stuff.

In case you don’t know, ITRDBFOR is an electronic forum (a listserver) subscribed to by most of the world’s dendrochronologists. What is most interesting is that Hughes and Briffa are co-authors of the response to Mann.

—– Original Message —–

From: Rob Wilson

To: ITRDBFOR@LISTSERV.ARIZONA.EDU

Sent: Sunday, 25 November, 2012 20:43

Subject: [ITRDBFOR] Comment to Mann et al. (2012) at Nature Geoscience

Dear Forum,

In February of this year, Mike Mann and colleagues published a paper in Nature Geoscience entitled, “Underestimation of volcanic cooling in tree-ring based reconstructions of hemispheric temperatures”. Their main conclusion was that a tree-ring based Northern Hemisphere (NH) reconstruction of D’Arrigo et al. (2006) failed to corroborate volcanically forced cold years that were simulated in modelling results (e.g. 1258, 1816 etc). Their main hypothesis was that there was a temporary cessation of tree growth (i.e. missing rings for all trees) at some sites near the temperature limit for growth.

This implies Dendrochronology’s inability to detect missing rings results in an underestimation of reconstructed cold years when different regional chronologies are averaged to derive a large scale NH composite.

We scrutinized this study and wrote a response to Nature Geoscience. We are pleased to announce that our comment, along with a reply by Mann et al., was finally published on Nov. 25, 2012 (http://www.nature.com/ngeo/journal/vaop/ncurrent/index.html) – 8 months after submission.

Our comment focuses on several factors that challenge the Mann et al. (2012) hypothesis of missing tree rings. We highlight problems in Mann et al.’s implementation of the tree ring model used, a lack of consideration for uncertainty in the amplitude and spatial pattern of volcanic forcing and associated climate responses, and a lack of any empirical evidence for misdating of tree-ring chronologies.

We look forward to a continued discussion on this subject.

Kevin J. Anchukaitis, Petra Breitenmoser, Keith R. Briffa, Agata Buchwal, Ulf Büntgen, Edward R. Cook, Rosanne D. D’Arrigo, Jan Esper, Michael N. Evans, David Frank, Håkan Grudd, Björn Gunnarson, Malcolm K. Hughes, Alexander V. Kirdyanov, Christian Körner, Paul J. Krusic, Brian Luckman, Thomas M. Melvin, Matthew W. Salzer, Alexander V. Shashkin, Claudia Timmreck, Eugene A. Vaganov, and Rob J.S. Wilson

—

———————————————————————–

Dr. Rob Wilson

Senior Lecturer in Physical Geography

School of Geography & Geosciences

University of St Andrews

St Andrews. FIFE

KY16 9AL

Scotland. U.K.

http://earthsci.st-andrews.ac.uk/profile_rjsw.aspx

“…..I have wondered about trees. They are sensitive to light, to moisture, to wind, to pressure. Sensitivity implies sensation. Might a man feel into the soul of a tree for these sensations? If a tree were capable of awareness, this faculty might prove useful. ”

“The Miracle Workers” by Jack Vance

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UPDATE: RomanM locates the Mann paper in comments, writing:

The original Mann article seems to be available at his web site:

http://www.meteo.psu.edu/holocene/public_html/shared/articles/MFRNatureGeosciAdvance12.pdf

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UPDATE2: More from the listserv

From: “Malcolm Hughes” <mhughes@LTRR.ARIZONA.EDU>

To: <ITRDBFOR@LISTSERV.ARIZONA.EDU>

Sent: Monday, 26 November, 2012 16:42

Subject: Re: [ITRDBFOR] Comment to Mann et al. (2012) at Nature Geoscience

> Ron – no dendrochronologists were involved in the offending Mann et al

> 2012 paper. What Rob described was the response of a number of us to

> some of the multiple flaws in the original paper. Cheers, Malcolm

>

> Malcolm K Hughes

> Regents’ Professor of Dendrochronology

> Laboratory of Tree-Ring Research

> University of Arizona

> Tucson, AZ 85721

—– Original Message —–

From: RONALD LANNER

To: ITRDBFOR@LISTSERV.ARIZONA.EDU

Sent: Monday, 26 November, 2012 03:48

Subject: Re: [ITRDBFOR] Comment to Mann et al. (2012) at Nature Geoscience

“a temporary cessation of tree growth” resulting in no rings for all trees? Now that is a hypothesis that I am willing to bet good money has no empirical support since studies of trees began 200 years or so ago. Speculation this bald could give dendrochronologists a bad name.

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UPDATE 3: Rob Wilson leaves this comment at Bishop Hill today, bolded section is my emphasis:

Nov 26, 2012 at 9:00 PM | Rob Wilson

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