First here is Dr. Keith Briffa’s response in entirety direct from his CRU web page:
My attention has been drawn to a comment by Steve McIntyre on the Climate Audit website relating to the pattern of radial tree growth displayed in the ring-width chronology “Yamal” that I first published in Briffa (2000). The substantive implication of McIntyre’s comment (made explicitly in subsequent postings by others) is that the recent data that make up this chronology (i.e. the ring-width measurements from living trees) were purposely selected by me from among a larger available data set, specifically because they exhibited recent growth increases.
This is not the case. The Yamal tree-ring chronology (see also Briffa and Osborn 2002, Briffa et al. 2008) was based on the application of a tree-ring processing method applied to the same set of composite sub-fossil and living-tree ring-width measurements provided to me by Rashit Hantemirov and Stepan Shiyatov which forms the basis of a chronology they published (Hantemirov and Shiyatov 2002). In their work they traditionally applied a data processing method (corridor standardisation) that does not preserve evidence of long timescale growth changes. My application of the Regional Curve Standardisation method to these same data was intended to better represent the multi-decadal to centennial growth variations necessary to infer the longer-term variability in average summer temperatures in the Yamal region: to provide a direct comparison with the chronology produced by Hantemirov and Shiyatov.
These authors state that their data (derived mainly from measurements of relic wood dating back over more than 2,000 years) included 17 ring-width series derived from living trees that were between 200-400 years old. These recent data included measurements from at least 3 different locations in the Yamal region. In his piece, McIntyre replaces a number (12) of these original measurement series with more data (34 series) from a single location (not one of the above) within the Yamal region, at which the trees apparently do not show the same overall growth increase registered in our data.
The basis for McIntyre’s selection of which of our (i.e. Hantemirov and Shiyatov’s) data to exclude and which to use in replacement is not clear but his version of the chronology shows lower relative growth in recent decades than is displayed in my original chronology. He offers no justification for excluding the original data; and in one version of the chronology where he retains them, he appears to give them inappropriate low weights. I note that McIntyre qualifies the presentation of his version(s) of the chronology by reference to a number of valid points that require further investigation. Subsequent postings appear to pay no heed to these caveats. Whether the McIntyre version is any more robust a representation of regional tree growth in Yamal than my original, remains to be established.
My colleagues and I are working to develop methods that are capable of expressing robust evidence of climate changes using tree-ring data. We do not select tree-core samples based on comparison with climate data. Chronologies are constructed independently and are subsequently compared with climate data to measure the association and quantify the reliability of using the tree-ring data as a proxy for temperature variations.
We have not yet had a chance to explore the details of McIntyre’s analysis or its implication for temperature reconstruction at Yamal but we have done considerably more analyses exploring chronology production and temperature calibration that have relevance to this issue but they are not yet published. I do not believe that McIntyre’s preliminary post provides sufficient evidence to doubt the reality of unusually high summer temperatures in the last decades of the 20th century.
We will expand on this initial comment on the McIntyre posting when we have had a chance to review the details of his work.
K.R. Briffa
30 Sept 2009
- Briffa, K. R. 2000. Annual climate variability in the Holocene: interpreting the message of ancient trees. Quaternary Science Reviews 19:87-105.
- Briffa, K. R., and T. J. Osborn. 2002. Paleoclimate – Blowing hot and cold. Science 295:2227-2228.
- Briffa, K. R., V. V. Shishov, T. M. Melvin, E. A. Vaganov, H. Grudd, R. M. Hantemirov, M. Eronen, and M. M. Naurzbaev. 2008. Trends in recent temperature and radial tree growth spanning 2000 years across northwest Eurasia. Philosophical Transactions of the Royal Society B-Biological Sciences 363:2271-2284.
- Hantemirov, R. M., and S. G. Shiyatov. 2002. A continuous multimillennial ring-width chronology in Yamal, northwestern Siberia. Holocene 12:717-726.
Now a few points of my own:
1. Plotting the entire Hantemirov and Shiyatov data set, as I’ve done here, shows it to be almost flat not only in the late 20th century, but through much of its period.
How do you explain why your small set of 10 trees shows a late 20th century spike while the majority of Hantemirov and Shiyatov data does not? You write in your rebuttal:
“He offers no justification for excluding the original data; and in one version of the chronology where he retains them, he appears to give them inappropriate low weights.”
Justify your own method of selecting 10 trees out of a much larger data set. You’ve failed to do that. That’s the million dollar question.
Briffa Writes: “My application of the Regional Curve Standardisation method to these same data was intended to better represent the multi-decadal to centennial growth variations necessary to infer the longer-term variability in average summer temperatures in the Yamal region: to provide a direct comparison with the chronology produced by Hantemirov and Shiyatov.”
OK Fair enough, but why not do it for the entire data set, why only a small subset?
2. It appears that your results are heavily influenced by a single tree, as Steve McIntyre has just demonstrated here.
As McIntyre points out: “YAD061 reaches 8 sigma and is the most influential tree in the world.”
Seems like an outlier to me when you have one tree that can skew the entire climate record. Explain yourself on why you failed to catch this.
3. Why the hell did you wait 10 years to release the data? You did yourself no favors by deferring reasonable requests to archive data to enable replication. It was only when you became backed into a corner by The Royal Society that you made the data available. Your delays and roadblocks (such as providing an antique data format of the punched card era), plus refusing to provide metadata says more about your integrity than the data itself. Your actions make it appear that you did not want to release the data at all. Your actions are not consistent with the actions of the vast majority of scientists worldwide when asked for data for replication purposes. Making data available on paper publication for replication is the basis of proper science, which is why The Royal Society called you to task.
Read about it here
Yet while it takes years to produce your data despite repeated requests, you can mount a response to Steve McIntyre’s findings on that data in a couple of days, through illness even.
Do I believe Dr. Keith Briffa? No.
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“My colleagues and I are working to develop methods that are capable of expressing robust evidence of climate changes using tree-ring data.”
I caught that too. As a scientist, I’m appalled at such a statement. I was reading through a stats book this morning and ran across the following: “Scientists often hope passionately that a particular experimental result will turn out to be statistically significant, so that they can have a paper published in Nature and get promoted, but that doesn’t make it right.” – Michael J. Crawley, Imperial College, London.
This is not evidence of fraud, it’s evidence of an ivory tower mentality (as we see at RealClimate all too often). It’s Human for someone to want to protect his life’s work, if that’s how he earns his reputation and status. `Protecting it from what?’, is the question. The answers are, (1) competing researchers and (2) criticism.
“Leif Svalgaard (09:14:03) :
Although YAD061 looks like an outlier, the other trees do show a rise from ~1820 to today [albeit smaller] so the record [based on those threes] does not look entirely flat to me.
REPLY:[…]There could be hundreds of reasons besides climatic temperature change.
So why the fascination with those trees in the first place? If there can be so many reasons besides climate changes, why get all hot under the collar about something that apparently is a poor indicator?”
Leif,
I’d guess because people want to replicate the damned study and keep getting stonewalled. If all of the details on the study were forthcoming it might be possible to finally show whether it actually stands on its own legs or not. If you don’t believe trees are thermometers and a scientist blindly gives you final numbers saying that they are, you’re going to want to know how they arrived at them, no?
Bless you Dr. Briffa for posting a response. I hope your health improves.
I read through the RealClimate response. They are very, very worried. You could tell that in their attack on SM. Steve has been very careful in saying we need to get a response from Briffa (it’s the comments that have been harsh). RC in their haste to post something, have made themselves out as complete fools. By attacking Steve they have done the exact thing they are complaining about. This is what people do when they are not thinking very well.
I’m trying to put this whole mess in a nut shell for the sheeple.
So let me see if I get this straight.
Michael Mann’s cherry picked ice core data that produced the infamous hockey stick graph, correlated with Keith Briffa’s cherry picked bristlecone pines tree ring data that confirmed the sharp rise in global temperatures noted on the hockey stick graph, both of which by the way have now been discredited, was the basis for forming public policy decisions that have a grave affect on all of mankind.
Can this statement be improved?
Al Pipkin,
As a fellow ME I would also like to assert that I will never use a tree as a thermometer and also wouldn’t recommend it to others.
Anthony, I told Tom Fuller when he was doing his piece that this isn’t quite the smoking gun it’s been made out to be, and that I don’t think Watts understands it.
I thought I was being too harsh, but you’ve shown that here. Steve has already explained that comparisons to H&S 2002 are invalid.
Try combining the different trees without Yad06, before you make your second claim.
The third claim is valid, and it would be good if him or H&S released the full dataset on their trees, so people can evaluate his methods. Until he does so, this is just speculation.
It is painful to read RC. I tried reading http://www.realclimate.org/index.php/archives/2009/09/hey-ya-mal/ but my eyes glazed up…
It isn’t a writing style I like. It is dismissive and childish at the same time.
The gavin name plot is interesting. Just because you can find a “hockey stick” doesn’t mean it is valid to what you are trying to measure.
Perhaps they could learn something from that?
It is well known that vegetation in general, and that includes trees, grow better with greater CO2 concentrations. Why, when confronted with a hockey stick in the thickness of the rings in a tree, do they suppose that it is a temperature signal? We KNOW that temperature has varied quire remarkably in the past. If the tree doesn’t show that clearly, it is not a good temperature proxy. If it shows a hockey stick, then it MAY BE a good proxy for CO2 concentration instead, as CO2 concentration is supposed to have the shape of a hockey stick. More CO2 = more growth, it is consistent and doesn’t necesarily imply greater temperature.
I would even suggest to define *scientific result*, in any area of knowledge, as the set composed by: DATA obtained according to the scientific method (raw, or processed under peer-monitoring, if raw data cannot be stored – e.g. LHC) + INTERPRETATION based on consistent logical and mathematical arguments (peer-reviewed articles) + ALGORITHMS used to interpret the data. Any scientific result, to deserve that name, should include all of them! If not, it should be regarded by publishers as non-scientific. It should not only be peer-reviewed, but peer-re-reviewable. If interpretation is given without access to the original data that backs it and/or algorithms used to manipulate it, then it is as reliable as the boy who cried wolf. Scientific misconduct would still occur under this definition – the world is not perfect -, but it would definitely truncate it, to a much lower level than the one we experience today.
Dr. Briffa’s sentence, “My colleagues and I are working to develop methods that are capable of expressing robust evidence of climate changes using tree-ring data”. That sound very much like the old example of a drunk who uses a lamp post for support rather than enlightenment. His descriptioin of his own work makes it nothing more than scientific support for a political agenda.
“My colleagues and I are working to develop methods that are capable of expressing robust evidence of climate changes using tree-ring data”
Let me help you there Mr Briffa.
1. Design your experiment and analysis prior to gathering data.
2. Control the variables that can be controlled. e.g. Ring cores to be gathered from tree species where the response to temperature is both known, and the current temperature is such that it lies at the midpoint of the up-curve or the down-curve of that species response to temperature variation.
3. Only use trees from virgin forests.
4. Use huge sample sizes, tens and hundreds of thousands, not four or five a given period and location. So that random the noise to signal ratio is reduced.
5. Randomise the selected trees systematically, (hint gather the data from the tree closest to a randomly generated coordinate within suitable forests.
6. Record and publish every step of the process, so that any errors can be spotted by peer reviewers, and those trying to replicate your work post publication.
“In 1961, a 27-year-old assistant professor of psychology, Stanley Milgram, wanted to study obedience to authority…” He found that, under pressure from the experimental scientists, 65% would administer electrical shocks they had been told were lethal (although they were not). Milgram was hounded out of Academia for this research – a case of “shoot the messenger” I think. In fact, all participants were debriefed, it seems debriefed perfectly well, and several were positively grateful what they had learned, and changed as a result. From “Opening Skinner’s Box” by Lauren Slater.
The most vulnerable to this kind of behaviour were people who were normally gentle and kind, and just wanted to be liked. Mavericks were far more likely to refuse to participate.
I needed to understand all this, to grasp what had happened when just such an individual, for whom I had had a lot of respect, turned my own life upside-down because I didn’t fit his “authority”. I see the same face in Briffa, both young (here) and current (at Jennifer Marohasy). Trying to please. I feel sorry for the man. But am I right?
I still want the truth out re Climate Science.
As part of Briffa’s defense, he offers 4 citations, three of which he was the lead or sole author. The old political adage that if you say it often enough and loud enough, people will believe it is true seems to be alive and well.
That one dramatic sample in YAD061 would be dramatically reduced if averaged with the other samples, unless it was given more weight.
A thought occured to me that all this paleodendrology only gives an indication of how warm the summers were and no indication of how cold the winters were over the same period. Maybe its not significant.
“I note that McIntyre qualifies the presentation of his version(s) of the chronology by reference to a number of valid points that require further investigation.”
And there’s the admission.
Steve McIntyre replies to Briffa:
http://www.climateaudit.org/?p=7257#comments
Leif Svalgaard (09:36:45) :
‘So why the fascination with those trees in the first place? If there can be so many reasons besides climate changes, why get all hot under the collar about something that apparently is a poor indicator?’
Perhaps you should be asking Al Gore, Michael Mann, Alan Hansen et al that question. They are after all the ones who are using the data to force their climate change agenda.
What the stations say
http://data.giss.nasa.gov/cgi-bin/gistemp/findstation.py?datatype=gistemp&data_set=1&name=&world_map.x=515&world_map.y=50
no hockeystick in Yamal, check Salehard: 40’s as hot as the 90’s,
local temperature doesn’t match extreme trees.
It’s interesting to see the grants Briffa’s involved in:
£106,423: ECOCHANGE- Challenges in assessing and forecasting biodivesity and ecosystem changes in Europe
£125,000: Climate Change – Fellow 1 -modelling of the Earth’s climate
£123,789: Process-based methods in the interpretation of tree-growth/ climate relationships
£121,880: To What Extent Was The Little Ice Age A Result Of A Change In The Thermohaline Circulation?
£226,981: Quantitative applications of high resolution late Holocene proxy data sets: estimating climate sensitivity and thermohaline circulation influences
£3,732: Statistical callibration of Eurasian tree ring records.
£1,000: ARC (Academic Research Collaboration) :Long tree ring chronologies in the Alps.
Taken from http://www.cru.uea.ac.uk/cru/research/grants.htm
Grabbed a copy, just in case.
Ecotretas
Look… I am a plumber… can someone please explain how the tree ring data can override the existing arctic temperature records? It seems to me that this alone puts the lie to the Yamal hockey stick… Like I said… I’m a plumber… what am I missing here??
Mike Bryant
Briffa just wants Russian grant money, obviously.
Leif Svalgaard (09:36:45) : “So why the fascination with those trees in the first place? If there can be so many reasons besides climate changes, why get all hot under the collar about something that apparently is a poor indicator?”
I think you know the obvious answer to that, Leif, is because Briffa et al. work has been the “industry standard” for so much research that reproduce the failed, broken, and discredited hockey stick.
That stick which is still the darling of the IPCC and the Gore-Media-Complex.
What gets many hot under the collar is not the trees or them being a poor indicator. The trees are what they are and they do what they do.
What really grinds the gears, for me, is is that so VERY much research is depending upon these cherry-picked (or should I say larch “cone-picked”) samples as leverage to extrapolate a whole universe of GCM unreality…and propagate that across the scientific “peer-reviewed” political establishment and the media….who then feed it to the populous.
It truly is the tail wagging the dog here…and thanks to folks like McIntyre, Watts, and other whistle-blowers, this is going to stop.
And I can only think it will in the long run benefit you and your research tools and funding…to get Science back where it is supposed to be: the pursuit of truth.
Chris
Norfolk, VA, USA
As a cheering member of the peanut gallery, I wonder how even-handed a “peer” review would be. Seems as though since AGW is settled science, then these peers would have an interest in perpetuating the notion of AGW.
I’m not confident this would play out well for Mr. McIntyre. However, transparency is truly disinfectant. Hopefully, the remainder of Mr. Briffa’s work will become transparent in fewer than another 10 years. Maybe his peers will revisit his work – objectively.
Assuming that the goal of Briffa, his team, and those criticizing his work, is to produce honest, professional and ethical work, then there is no justification for Briffa or the journals that published work to withhold any data sets, including meta data. All of relevant data should be produced and evaluated before the knife fighting goes any further.