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
==============================================================
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
Hi Again,
Our comment and Mann’s response to it can be accessed from this link:
http://www.st-andrews.ac.uk/~rjsw/all%20pdfs/Anchukaitisetal2012.pdf
his original paper is here:
http://www.meteo.psu.edu/holocene/public_html/shared/articles/MFRNatureGeosci12.pdf
Hmmm – what do I think of Mann’s response. Where does one start!
Well – he has provided NO evidence that there are stand (regional) wide missing rings for major volcanically forced cool years. Let’s focus on 1816 as an example – The “Year without a Summer” – where historical observations clearly show cool summer conditions (related to Tambora in 1815) throughout NE North America and Europe. Using either long instrumental records or historical indices, there is no evidence of a stand-wide missing ring in temperature sensitive tree-ring chronologies in Labrador, Scotland, Scandinavia or the Alps. Mann would probably turn around and say – well, actually, my model says that 50% of the sites would express missing rings – just not those in NE America and Europe. Sheesh!
To be less flippant, and putting aside criticisms of tree-ring series as proxies of past climate, the method of crossdating is robust and easily verifiable by different groups. I would be surprised if Mann has ever sampled a tree, looked at the resultant samples and even tried to crossdate them. He has utterly failed to understand the fundamental foundation of dendrochronology.
I undertook most of the analysis in D’Arrigo et al. (2006) and we clearly stated in the original paper that due to the paucity of sites (only 19) around the northern hemisphere, the reconstruction was most robust at time-scales greater than 20 years. Using the D’Arrigo reconstruction to look at inter-annual response to volcanically forced cool summers was a poor choice. Maximum density records, as shown in our response, would clearly be a far superior tree-ring parameter to use for such an exercise – as Briffa clearly showed in 1998. See also this paper:
http://www.st-andrews.ac.uk/~rjsw/all%20pdfs/D’Arrigoetal2009a.pdf
There is a lot more I could say, but this can all wait until next week at the AGU Fall Meeting.
One final observation is I urge you to look at Figure 1 in Mann’s original article. The instrumental record (black line) in Figure 1a (upper panel) clearly does not show strong cool temperatures in 1884 related to Krakatoa as seen in the two models. Following Mann’s hypothesis, the instrumental data must be wrong.
Time for some red wine
Rob
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Caleb says:
November 25, 2012 at 7:53 pm
A very good point, Caleb. I concur with your suspicions regards Briffa. Here’s hoping we are right..
“Set the carbon free! Cold is not good.” – John F. Hultquist
Good teeshirt. I want one!
“and a lack of any empirical evidence for misdating of tree-ring chronologies.”
Wow – knock out punch right there. Will Mann sue? His grasp on the throats of tame editors seems to be loosening a tad. Will he show his empirical evidence? For example, if tree rings are missing in certain tree populations, they should be discernible in other populations thereby corroborating the theory. But somehow, I doubt that he will. Even with this clear slap in the face from his colleagues.
My interpretation is if the models predict it should have happened then Nature is at fault. End of story. /disgust
Charting the non-existant? Rather sums up the whole AGW agenda, doesn’t it.
Yeah, the BEST data and study which was touted in press conferences, rejected as crap and unpublished till today, a year and half after the tall pronouncements.
With luck, coverage of the forthcoming AGU meeting will be dominated by whatever news from Curiosity has the JPL scientists excited, rather than by the usual AGW doomsterism. Mars vs. Mann in the publicity battle? I’d bet on Mars.
Mann is brave in his obfuscation because he knows there are just too many powerful bankers, politicians, and academics who can’t afford to have the CAGW gravy train derailed. Note that Mann’s legal fund is being backed by George Soros, the green energy hedge fund backer and currency speculator–tells you everything you need to know.
On the same theme, JIm Bouldin (of RC) has started a blog that seems to have gone largely unnoticed except by J Jackson at CA. Jim has a series of posts (two currently) on the subject of
“Severe analytical problems in dendroclimatology”
in which he is very critical of tree ring reconstructions, saying
“Each of these issues by itself would be a serious problem, but collectively they render unreliable all long-term estimates of climate change from ring widths”
He also heaps praise on a 2009 paper by Craig Loehle. See
http://ecologicallyoriented.wordpress.com/2012/11/24/severe-analytical-problems-in-dendroclimatology-part-two/
Yes, from what I’ve read I think Briffa is more scientific, in the best sense, than others involved, It would be nice if he’d come off the fence! I know it’s hard, but real science is about honesty: not fooling yourself, and so not fooling others (Feynman).
Missing years may not be related to cold years, but to the oceanic currents circulations in the North Atlantic. There is a temporal misalignment between atmospheric pressure variability affecting the summer precipitations and the temperature changes. Both are factors in the tree growth.
This graph
http://www.vukcevic.talktalk.net/AP-AMO.htm
shows relationship between the Sub-Arctic summer atmospheric pressure and temperature anomalies. Yamal (Mann et al) peninsula is on the Arctic Circle.
Hence, dendrochronologists can’t accurately describe the temperature movement since they are not always synchronous with local precipitations.
Steven Mosher’s drive to his office is occasionally disrupted by road works, so he has some missing minutes or even hours in his work schedule.
Mann’s finally reached a new level in bad science – basing the conclusions of a paper on missing evidence.
Policy Guy asked
“So how does one demonstrate that a tree does not generate a ring under certain circumstances? Personally, I’m not a dendrocrat, but it would appear to be a convenient theory for some unknown purpose, for how would one know? Tree rings are not date stamped.”
But in a sense they are. Dendro-dating uses ring-width patterns to compare timber samples with sufficient rings with others with longer ring-series until a chain of matches is established to a sample of known date. I’d suggest this technique would provide the “missing empirical evidence” referred to by Anchukaitis et.al, and is in fact what they’re implying. “Missing ring” series would be matched with series from nearby, but generally warmer locations until matches are found for patterns pre and post the postulated “ring-gaps” but with the “missing rings” intact. The process would likely require a lot more work than was involved in the original ring-proxy analysis, and of course would require that suitable ring-series were available.
Given the apparent absence of evidence it doesn’t say much for the peer-review process involved in the Mann paper.
So while the rising heat content in the oceans due to CO2 keeps missing, the missing cold in tree rings isn’t missing at all?
Do I miss something here?
Dendros are jumping ship it seems to me LOL
Anyone who cites Jack Vance (Dr. Rob Wilson) has got to be on the right side.
/Mr Lynn
Rob Wilson posted to the dendro list in part:
Guess it’s time for the reminder that hard data trumps models. The action should be on proving the data wrong, not assuming the models are right.
Steven Mosher says:
November 25, 2012 at 7:02 pm
Well, Mann did have the good sense to use BEST data in his response.
Did BEST create any new raw data ??
This is classic. Once again Mann et al. question empirical data because it fails to match a model run. We saw this in MBH98 and more recently in the GSA presentation of Mann, Kozar, and Emanual:
https://gsa.confex.com/gsa/2012AM/webprogram/Paper206358.html
Scientists everywhere should be shaking their heads in disbelief. This is completely ass-backwards. Empirical data is used to verify and constrain models, not the other way around.
and deer crap over newly opened routes.
http://wattsupwiththat.com/2009/10/02/a-hands-on-view-of-tree-growth-and-tree-rings-one-explanation-for-briffas-yad061-lone-tree-core/#more-11409
The original Mann article seems to be available at his web site:
http://www.meteo.psu.edu/holocene/public_html/shared/articles/MFRNatureGeosciAdvance12.pdf
Louis Hooffstetter says:
I am always amused here when people who have probably never actually done science believe that they understand science better than those who have. In fact, the relationship between models and empirical data works both ways. Sometimes the data points out problems with the models and sometimes the models point out problems with the data, which is, after all, not ordained by God.
In fact, as a modeler, I can remember many times when I have used modeling to find problems with the data. For example, one time we had some OLED devices coated and I found that my optical model was quite insistent on the notion that the layer of Aluminum (Al) was about 300A thick, not 200A thick and this seemed to be a quite robust result not sensitive to other assumptions (like other layer thicknesses). We asked the coaters to check their coater for the Al and they came back and told us that their “tooling factor” turned out to be off by a factor of 3/2…I.e., the modeling was precisely correct in detecting a problem with the empirical data.
Whether the problems in the case of volcanic cooling end up to be with the data or the models or some combination of the two is still unsettled, but to just assume that it is a problem with the models and not with the data is no more scientific than to assume the opposite. One has to entertain both possibilities.
Rome wasn’t built nor did it fall in a day. The edges of the Empire are crumbling under the weight of overextended extrapolation, logical fallacies, and arrogance.
”There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.” – Mark Twain
Stephen Rasey says:
November 25, 2012 at 9:04 pm
Eight months! to get published a letter questioning a paper.
Biffra should have come here. It would have been posted in it entirety in less than eight hours — and probably done more good for both sides of the debate.
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I would have liked to have been a fly on the wall for the internal debate about allowing the publication of the letter !!
Stephen Rasey says:
November 25, 2012 at 9:04 pm
Eight months! to get published a letter questioning a paper….
_____________________________________
AH, but the timing is perfect. Just before the next Eco-Fest to renew Kyoto. Makes one wonder….
Thanks for the link to Mann’s paper, RomanM. Because of this practice:
“Trees growing near the latitudinal or elevational treeline are typically selected for use
in reconstructing past temperature changes”
The detection of warm is much more likely than cold, since the trees are already at the threshold of growth/no growth. It seems to me to rectify this, trees must be chosen at an “elevational treeline”, where there are dead trees at higher altitude that grew when the climate was warm to be included in the dataset. The idea that trees are thermometers rather than general overviews of optimal/suboptimal climate for tree growth is silly. To extend this into sub-degree discernment of ‘climate change’ lacks sanity.