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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In order to photosynthesize, to produce energy for growth, all trees need air (gases), heat, light and water. Without any one of these elements there would be no growth. Using a specific combination of these essential elements I have developed a Photosynthesis Index (P-Index). The P-Index has a range from 0-60. Photosynthesis occurs about 6.9, less than this it does not occur.
When comparing (14 years daily data for a location in the UK), maximum Temperature (Tx) against the P-Index some interesting results were shown. Whilst overall correlation between the two sets was 0.63, which could be considered reasonably significant. When I plotted Tx individual degrees C low to high against the P-Index, it showed a large number of days when the photosynthesis trigger point (6.9) wasn’t reached and the Tx could have been anywhere in the range between 0-27DegC. In other words photosynthesis can occur with a Tx 8DegC and not occur with Tx 27degC. Depending on species with Tx >29DegC, but particularly with a P-Index of >40, may cause heat stress and hence also limited photosynthesis.
My conclusion to this would be, tree-ring growth is not an accurate proxy for temperature reconstruction. (data available on request)
Mike Jowsey says:
November 25, 2012 at 10:20 pm
“Set the carbon free! Cold is not good.” – John F. Hultquist
Good teeshirt. I want one!
___________________________________
Add Co2 = Plant Food on the back or maybe a Josh cartoon link
The best comments on the BEST data.
link 1
link 2
[Fixed links. -ModE ]
From Gail Combs on November 26, 2012 at 6:58 am:
The best comments on the BEST data.
Drop the parts of the URL’s from question mark to end to make the links work.
Link 1: http://bishophill.squarespace.com/storage/BEST_PRscr.jpg
Link 2: http://bishophill.squarespace.com/storage/Photo%200.jpg
Gail, neither of your links work. 🙁
Gail Combs says:
November 26, 2012 at 6:58 am
The best comments on the BEST data.
link 1
link 2
=====================
Broken linkys
Joel… Long time no see. Glad to have you back.
You do raise a good point. That said, your example does not fit as well in this case. In your example, the model points to a single miscalibrated machine. That is not the case here.
“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.”
If their critique holds up, this is flawed piece of work.
Mike Alexander aka Sonicfrog.
Kadaka, still no joy.
.
Sure, trees sometimes don’t produce rings when it is cold – that is when they die.
A tree that is living produces rings, end of story. Anyone from the Agro department have anything further to add to that statement?
joeldshore says:
Sometimes the data points out problems with the models and sometimes the models point out problems with the data… One has to entertain both possibilities.
Good point and I agree. When something doesn’t jibe, you check everything until you find the problem. This is scientific objectivity. My point was that in general, Mann et al. appear to lack objectivity, and have much more faith in their models than in actual data.
Jimbo says:
November 26, 2012 at 5:29 am
“and deer crap over newly opened routes.”
Make that reindeer. They are actively herded in the Yamal region and their numbers have doubled since WWII:
http://www.arcticbiodiversity.is/index.php/en/ecosystem-services/reindeer-herding
bob asked:
Speaking of the BEST dataset, can someone tell me why the thing diverges so much from all other datasets?
I believe the BEST records only include land surface temperatures. They tend to be warmer than the atmosphere over the oceans.
Mann can’t see the wood from the tree rings?
Jeff Alberts said on November 26, 2012 at 7:58 am:
Kadaka, still no joy.
I just right-clicked, opened in new tab, both links I provided. Both worked.
I right-clicked, copied link location, and pasted into my other browser, in case they were only working because the pics were in main browser’s cache. Both loaded fine.
Must be on your end, you’re blocked somehow.
Here are the embedded versions:
link 1
link 2
When accidently following that link to Mann’s paper, (I never willingly support anything of Mann’s and I clicked the link drooling over getting to read the paper. retch retch) and reading that bull about models feeding models and how that indicates missing tree rings, I was struck by a mental image of Johnny Carson doing his ‘Carnac the magnificent’ sketch.
All sham for the audience and weak minded. Only Johnny was only in it for the laughs and his magnificent salary.
It is curious that Mann has a response to Briffa et al ready in the same issue, as already mentioned eight months after. Isn’t modern science wonderful when buddies help buddies? To our detriment.
Joel Shore pops up again with misdirection. “I remember, I remember when the thickness of aluminum validated Mann’s method of the model shell game. Hmmm, was your model that indicated the likely tooling culprit fed by model data as Mann’s volcanic tree abortion scenario is; or anything like Mann’s carefully selected data along with his funny code that gets the same results no matter the data? I’ll bet you used definitive hard data that proved a coating issue before you ran the model… I doubt it. Your model was a short cut to help the business fix an error. Even though it seems to me that a coating thickness issue would have brought people right to the coating application tools for that specific layer.
In any case; it does seem that Briffa et al are going for the jugular, slow though that may be by their using facts versus false alarms and mystic passes of the AGW crowd.
It’s a tree-ring circus!
Bob, pay attention. The data is BEST. BEST data will obviously diverge from other data which is not BEST data, for example the dataset produced by Woodshole Oceanographic Reference Study Estimates.
Wouldn’t this undermine the rest of Mann’s work, if he is now saying tree rings aren’t accurate?
Jim Bouldin has been defensive of Mann, including at AMac’s site. I asked him about one ClimateGate post that dendros are not acting in concert with the principles of evolution, and are generally not thinking in terms of biology. He was very dismissive of this e-mail, but appears to be saying the same things now.
So science IS a self-correcting process?
And does anyone really want to encourage an environment where scientists (or anyone, including bloggers) can’t make a mistake?
OT
An important moment for the SC24, the solar magnetic field has finally changed polarity
http://www.vukcevic.talktalk.net/LFC6.htm
a bit later than expected.
“REPLY: When is it ever good sense to use data that has failed to pass peer review? – Anthony”
watch out for rhetorical boomerangs. you probably want to explore the multiple number of ways such a comment can backfire. And reading what Mann wrote would help.
If the tree has leaves or healthy needles,then it is living and WILL produce a ring,no matter how small. No ring,tree dead. And people still fall this crap? What is wrong with NA’s edumacational systems?
Mann’s missing tree rings.
Trenberth’s missing heat.
We’re allI missing something here.
“Given the apparent absence of evidence it doesn’t say much for the peer-review process involved in the Mann paper.”
Hear, hear! Far too much crap science is being published. It is time to expose those who facilitate the publication of crap science. Science is far too important for our future to continue to allow this to continue.