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« 28gate in the Scotsman | Main | 28 gate still running »
Monday
Nov262012

Lonely old Mann 

A group of prominent paleoclimatologists has written a paper rebutting one of Michael Mann's recent contributions to the scientific literature. The new paper was announced on the ITRBD Forum by Rob Wilson. The list of authors of the new paper is very long. Almost looks like they are ganging up on him. ;-)

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

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Reader Comments (173)

There are some authors whose work I choose not to read again, not as a game, but as the normal act of a normally intelligent mind.

Nov 26, 2012 at 8:27 AM | Unregistered CommenterGeoff Sherrington

Surprised to see the names of Briffa & Hughes in this. I wonder if this is a sign that Mann is being thrown to the wolves so to speak.

Nov 26, 2012 at 8:31 AM | Unregistered CommenterJack Cowper

Woohoo, a little revolution!

No matter how much we dislike Mann, I bet the thoughtful members of the paleoclimate field have grown to shudder at his name. Getting all the glory but at the same time taking their science up a blind alley. They probably get a lot of collective stick from other climate scientists for damaging other fields.

What we need now is a rebellion in the station data field. People who are fed up with the temperature record being continually adjusted to create more of a slope.

Incidentally I wonder how the paleo lot deal with the calibration of proxy records with a continually moving thermometer record?

Nov 26, 2012 at 8:38 AM | Unregistered CommenterTinyCO2

Isn't this an extraordinary development, given how nice Mann has been to so many within his own field over so many years? Chortle chortle.

Nov 26, 2012 at 8:43 AM | Registered CommenterRichard Drake

Keith Briffa again I note.

Nov 26, 2012 at 9:08 AM | Unregistered CommenterGeckko

Is this mann's Birnam Wood?

Nov 26, 2012 at 9:10 AM | Unregistered CommenterOtter

Good to see Keith in there. Onya, Keith! : )

Nov 26, 2012 at 9:14 AM | Unregistered CommenterChris M

I see ."we simply did not consider it " Briffa ... so why should we even consider this paper?

Nov 26, 2012 at 9:15 AM | Unregistered CommenterMikeHaseler

People may also be interested by the two posts on dendroclimatology by Jim Bouldin at his new blog Ecologically Oriented. Recommended reading.

Nov 26, 2012 at 9:47 AM | Registered CommenterJonathan Jones

Briffa.. and I believe Trenberth are savable. They are like Darth Vader.. yes they have done much harm in the service of the evil Empire, but if they could just be turned back to the good side of the Force.. I see good in them. Mann is Governor Tarkin, he doesn't even see anything wrong.

Nov 26, 2012 at 9:51 AM | Unregistered CommenterTheBigYinJames

Today, I have more respect for tree-ring guys than I had for them yesterday even though,

1- Tree-rings going missing because of volcanic eruptions seems like an easy enough hypothesis to understand and, presumably, to refute too.

2- It took 8 months to get the word out on that, "along with a reply by Mann et al". Some tree-ring guys are more equal than others.

3- They have in the ranks Keith Briffa, a tree-ring guy whose lack of credibility is second only to Mann's.

Nov 26, 2012 at 9:59 AM | Unregistered CommentersHx

See also the Jim Bouldin blog mentioned by JJ.
Bouldin heaps praise on a 2009 paper by Craig Loehle, and identifies 3 problems with dendroclimatology, saying in part 1

"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"

And this is from a member of the Realclimate team.

Nov 26, 2012 at 10:13 AM | Registered CommenterPaul Matthews

Jonathan,

is that really the same Jim Bouldin (of RC fame), who I last time encountered when he argued with me about screening fallacy over CA in connection to Gergis et al. (and then suddenly disappeared)? Reading his posts reminds me about CA discussion about the subject with bender, Loehle et al. (oh, those good old days!). He is even citing Craig's paper in a very positive light.

Nov 26, 2012 at 10:14 AM | Unregistered CommenterJean S

I have suspected for some time that Briffa might be having second thoughts.

Nov 26, 2012 at 10:15 AM | Unregistered CommenterPeter Stroud

Jean S, if you read other posts at the same blog they are certainly consistent with the Jim Bouldin I remember from RC, and he gets supportive comments from Hank Roberts, another well known RC supporter. I think we can be reasonably sure it is indeed him, and that he has changed his mind on dendroclimatology, but has not changed his mind on anything else.

Nov 26, 2012 at 10:21 AM | Registered CommenterJonathan Jones

When I first worked with traders in the City in 1986 I was told of a long German word (I confess I have forgotten every one of the polysyllables involved) that meant "everybody trying to get out of the door at the same time in a hurry". It was used of moments the markets 'self-corrected' and it seems to me to describe well what we are witnessing here. I don't think we are under compunction to ascribe dignity or honour to any individual at this stage (discerning motives is ever hard) but we are certainly free to enjoy the scene.

Nov 26, 2012 at 10:45 AM | Registered CommenterRichard Drake

I think a lot of us will need quite a bit of convincing about Trenberth in the light of his treatment of Chris Landsea.
A grovelling apology might be a good start.

Nov 26, 2012 at 10:54 AM | Registered CommenterMike Jackson

I'm sure Trenberth would give that verdict on his work the same weight that some of us sceptics would too. That's the great thing about the climate game - surprising new alliances every day. :)

Nov 26, 2012 at 11:02 AM | Registered CommenterRichard Drake

I was also going to mention the Bouldin posts (here and here), which begin with the summary "It is not an overstatement to say that all long term climatic estimates are suspect due to these (and other) issues." [Emphasis in the original.]

I'm curious as to Rob Wilson's response to this. Does he think this fair criticism, or overreaching?

Nov 26, 2012 at 11:29 AM | Registered CommenterHaroldW

Jonathan, Paul,
Same question as Jean S. It is the same Bouldin, who along with Doug Bostrom, filled numerous CA and Realclimate comments with their scribblings vehemently defensive of the circular method of screening proxies.

A sample of the incredible amount of confusion spread (no doubt due to his opposition to anything CA):

He didn't unearth them, one of his readers did. But it is not at all clear that this mistake by Gergis et al is in fact even a real problem--not nearly enough is known about exactly what the error was, much less what kind of impact on their study it will have. It has to do with how they did their calibrations. I've made several points over there since he raised this issue; the latest one is here: http://climateaudit.org/2012/06/08/gergis-et-al-put-on-hold/#comment-337241 Until Steve McIntyre addresses this "Screening Fallacy" issue (as he calls it), with conclusive, detailed analysis, he just doesn't have a case, period. As for the detrending, I think you're mixing up two different detending steps. The detrending of the tree cores to remove the age/size effect is not the issue, it's rather the detrending, during the instrumental data period of the (1) climate data and (2) site-level chronologies (mean ring value for each year, after removing the age/size effect).--Jim]

Want to see how blinded, his description of the screening fallacy problem was?

:It's just a foolish argument. It's this simple: trees respond to multiple potential external inputs and you want to find that set of trees that is responding most strongly and clearly to that external input in which you are most interested. This necessarily involves a selection process, and that selection process is based on the correlation between an observed process (radial tree growth) and a variable (temperature) that we know from many other lines of evidence is a legitimate physical driver of that observed process. The fact that other drivers can also affect that process, and might sometimes even be correlated with that observed process in a statistically confounding way, does not negate the legitimacy of this procedure.--Jim

Our friend Bouldin above, left out the fact that tree-rings produce noisy datasets and screening against the target of your choice could very well filter only *noise that resembles your target*, and nothing more.

Nov 26, 2012 at 11:32 AM | Registered Commentershub

I like this bit:

We look forward to a continued discussion on this subject.

If Mann's track record when receiving critical reviews is anything to go by, he won't even be talking to them.

Nov 26, 2012 at 11:34 AM | Unregistered CommenterGeckko

Shub:

A sample of the incredible amount of confusion spread (no doubt due to his opposition to anything CA) ...

Ah yes. Any words of gratitude and blessing in the new paper for the years of meticulous work by Steve McIntyre and his friends at Climate Audit? That could be part of the reason for the willingness of some names to be here. The mystery isn't so deep after all.

Nov 26, 2012 at 11:37 AM | Registered CommenterRichard Drake

"When I first worked with traders in the City in 1986 I was told of a long German word (I confess I have forgotten every one of the polysyllables involved) that meant "everybody trying to get out of the door at the same time in a hurry". "
Excellent, if the Germans don't have a word for something then then they will bang a suitable collection of words together to make one :)

Nov 26, 2012 at 11:44 AM | Unregistered CommenterEddy

Is an 8-month gap between submission & publication of this type of communication unusual?

Nov 26, 2012 at 11:46 AM | Unregistered CommenterAdam Gallon

Geckko:

"If Mann's track record when receiving critical reviews is anything to go by, he won't even be talking to them."

-----
No, but expect a few vicious Mannian tweets...

Nov 26, 2012 at 11:50 AM | Unregistered Commentercui bono

Yeah, not just Lonely Old Mann but Grumpy Old Mann, if past experience is anything to go by.

Nov 26, 2012 at 12:01 PM | Registered CommenterRichard Drake

The time to have been "rebutting one of Michael Mann's recent contributions to the scientific literature" was 1998, after the hockey stick paper appeared. Or, at very least, in 2003, after Soon & Baliunas, then McIntyre & McKitrick, had published.

The damage by the acquiescence of this "long list of authors" was done years ago.

Too little, too late.

Nov 26, 2012 at 12:09 PM | Registered CommenterMartin A

"We look forward to a continued discussion on this subject."

And by "discussion", I hope they mean further denunciation, ridicule and general making-fun-of Mr. Mann. I need popcorn.

Nov 26, 2012 at 12:16 PM | Unregistered Commenterdfbaskwill

This group of nasties will not be retracting their religious belief in AGW any time soon. That's for certain.

Nov 26, 2012 at 12:53 PM | Unregistered CommenterStephen Richards

Hi - Hi! We're your Dendro Boys - Ah-huh -
And have we got news for you - You better listen!
Get ready, all you lonely IPCC tree-ring huggers!
And leave that faux Nobel prize certificate at home. - Alright! -

CO2 is rising - but sea level's still just as low
According to all sources, Penn State's the place to go
Cause tonight for the first time
Just about half-past ten
For the first time in history
It's gonna start raining Mann...

It's Raining Mann! Hallelujah! - It's Raining Mann! Amen!
I'm gonna let FOIA and Climategate
Hockey-stick-whack Mann on his head
It's Raining Mann! Hallelujah!
It's Raining Mann! Every Yamal Specimen!
Short, bald, fat and green
Malicious and devious and wrong and just plain mean...

God bless Mother Nature, she's a single woman too
She took off to UEA and she did what she had to do
She got poor old Harry to upload some email files
So that each and every skeptic could find the perfect rile...

It's Raining Mann! Hallelujah! - It's Raining Mann! Amen!
It's Raining Mann! Hallelujah!
It's Raining Mann! Ameeeeeeeennnn!

Nov 26, 2012 at 1:24 PM | Unregistered CommenterDendro Boys

Look! A lone zebra!

Nov 26, 2012 at 1:44 PM | Unregistered CommenterDr Slop

Somone needs to seriously investigate the link between George Soros (the hedge fund manager aka currency manipulator) and Michael Mann (data manipulator). Soros' billions are (1) currently heavily invested in green energy companies and (2) the sugar-daddy for Mann's legal defense fund. Soros' green hedge fund even has Cathy Zoi, an ex-undersecretary of Energy under Obama, on staff. Conflict of interest, much? Please, investigatiove journalists need to look into this. Soros is like an octopus with tentacles up every skirt.

Nov 26, 2012 at 1:59 PM | Unregistered CommenterMann2Mann

Mann is still working his hockey stick while the dendro guys are only defending their branch. And they are right, these guys. They would defend it even more effectively if they were not afraid of losing their source of income. Dendro is much better than its reputation.

Nov 26, 2012 at 2:19 PM | Unregistered Commenterphi

Dr Slop: Look! A lone zebra!

Now, that's funny. :-)

Nov 26, 2012 at 2:33 PM | Unregistered CommentersHx

Briffa to Mann: "How you like me now, BIATCH."

Nov 26, 2012 at 2:54 PM | Unregistered Commenterrafa

rafa: Briffa to Mann: "How you like me now, BIATCH."

Why does that sound so familiar to me?

Nov 26, 2012 at 3:17 PM | Unregistered CommentersHx

It's REALLY NOT long ago that Wilson was all but trying to hump Mann's leg. Have things changed so suddenly? Excuse my cynicism but, after witnessing the way Wilson handles himself, and adding Briffa and Hughes into the mix, I'm not ready to party. This is historically a manifestly devious bunch of people.

Nov 26, 2012 at 4:45 PM | Registered CommenterSimon Hopkinson

Dear All,
Mann’s major flaw was to see something in his model which did not agree with “nature” and assumed that there must be something wrong with nature. Alas, if he had taken the trouble either (1) to speak to some of his dendrochronological colleagues or (2) look at some real tree-ring data to learn what “crossdating” is, he would have quickly realised that his hypothesis was wrong and would not have wasted a lot of time for many people.

In my opinion, not reading a paper just because Briffa is a co-author seems rather narrow minded. Feel free to froth at the mouth, but this just highlights how entrenched SOME of you are w.r.t. your ideas, opinions and biases.

Simon Hopkinson – such a comment is really not very helpful – but did, I guess, provide the impetus for me to write a quick comment.

Rob

Nov 26, 2012 at 5:28 PM | Unregistered CommenterRob Wilson

Rob Wilson:

In my opinion, not reading a paper just because Briffa is a co-author seems rather narrow minded. Feel free to froth at the mouth, but this just highlights how entrenched SOME of you are w.r.t. your ideas, opinions and biases.

Agreed.

Simon Hopkinson – such a comment is really not very helpful – but did, I guess, provide the impetus for me to write a quick comment.

Indeed, the dynamics of blog emoting can work for good as well as ill. :)

Thanks for this perspective Rob. I'm sure there will be others. There's a guy in Toronto, for example, who may well have a view.

Nov 26, 2012 at 5:37 PM | Registered CommenterRichard Drake

Rob, how did you find Mann's reply?

To me, who has been reading his papers very closely for almost ten years, it was exactly what to be expected from him. Apart from references to fossil-fuel industry etc, it was exactly like any reply to any previous criticism of his work. He does not see any problems in his work. He does not admit anything, and the reply letter could have easily started with "Anchukaitis et al. raise no valid issues regarding our paper" (as he wrote in the reply to M&M PNAS criticism). So my prediction is that the "wasting of time for many people" has not even really started yet. It's not about science, it's all about his ego.

Nov 26, 2012 at 5:58 PM | Unregistered CommenterJean S

Rob, please can you put a preprint on an archive or somewhere, so that people can read it? It's in a new and expensive journal that my uni does not subscribe to.

Nov 26, 2012 at 6:08 PM | Registered CommenterPaul Matthews

I have not been able to find the MFR reply online, but the original article may be found here.

Nov 26, 2012 at 6:38 PM | Registered CommenterHaroldW

Harold,

MFR reply to Anchukaitis et al is also available through Mann's web page here (Supplementary Figures).

Nov 26, 2012 at 6:49 PM | Unregistered CommenterJean S

Briffa, D'Arrigo, Esper, Hughes ....

This is like the College of Cardinals disrespecting the Holy Father! (Il Papa if you prefer)

Nov 26, 2012 at 7:24 PM | Unregistered CommenterHeretic

(Il Papa if you prefer) Nov 26, 2012 at 7:24 PM | Heretic

Nahhh...I think you mean Capo di Capo.

Nov 26, 2012 at 7:32 PM | Unregistered CommenterSnotrocket

Rob:

Feel free to froth at the mouth, but this just highlights how entrenched SOME of you are w.r.t. your ideas, opinions and biases.

I don't think you can understate the significance of experiences, Rob, in shaping our perspectives.

Simon Hopkinson – such a comment is really not very helpful – but did, I guess, provide the impetus for me to write a quick comment.

My experiences are what they are, Rob, and you're in no small part responsible for my cynicism. If, in the fullness of time, that subsides and gives way to trust and confidence, it will be because the balance of my experiences inspires the shift. I'll happily acknowledge it if/when that happens.

Somewhat OT, Rob, are you Scottish?

Nov 26, 2012 at 7:40 PM | Registered CommenterSimon Hopkinson

Rob Wilson

Welcome. I very much appreciate you taking the time to comment here.

Quote:
"In my opinion, not reading a paper just because Briffa is a co-author seems rather narrow minded. Feel free to froth at the mouth, but this just highlights how entrenched SOME of you are w.r.t. your ideas, opinions and biases."

I hope you can take time to maybe help change some opinions and biases. And perhaps understand how these opinions and biases have been propagated.

Nov 26, 2012 at 8:18 PM | Unregistered CommenterJack Cowper

if he had taken the trouble ... to speak to some of his dendrochronological colleagues ... he would have quickly realised that his hypothesis was wrong and would not have wasted a lot of time for many people.
Rob, some of us have been saying that since MBH98. What kept you?

Nov 26, 2012 at 8:45 PM | Registered CommenterMike Jackson

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

Nov 26, 2012 at 9:00 PM | Unregistered CommenterRob Wilson

Rob, I'll join you with this on the red wine.
But do tell, when are Climate scientists going to actually come fully out of the closet and state unequivocally;
1) Models are not, repeat, NOT, experiments
2) Mann' Hockey Stick is complete rubbish- and why.
3) The urban heat-island effect is real and is not adequately corrected by current "homogenisation" methods.
4) The near annual rewriting of the temperature record is scientifically absurd.

Nov 26, 2012 at 9:28 PM | Unregistered CommenterDon Keiller

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