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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Tilo (13:20:19) :
Thanks for your screen grab of your comment.
http://2.bp.blogspot.com/__VkzVMn3cHA/SsUMIzGbPXI/AAAAAAAAAFI/3o4j7swEoDA/s1600-h/Briffa_Yamal_RC_screen3.JPG
The real beauty of that is not the reasonableness of your contribution which failed moderation, but the example of the spittle-flecked ranting which appears in the post above which apparently was quite acceptable to the moderator.
It serves to remind me why I don’t visit RC. I have come to the conclusion that it’s sole purpose is as a therapeutic aid for people with personality disorders.
RE: brazil84 in two separte posts
(Re the assertion by AGWers that Denialists think it is a conspiracy) “I think this is a warmist strawman. It’s not necessary for there to be a conspiracy for “groupthink” to take place…For the most part, deniers such as myself DO NOT claim that there is a conspiracy among climate researchers. And DO NOT claim that climate researchers are getting rich from concern over global warming.”
My thoughts exactly. Well said sir/madam. AGW is a groupthink catastrophe.
10 years on Dr Briffa says he and his colleagues are working to improve the robustness of the results showing that tree ring data reflects climate change!
So where were the caveats in the original paper and why were its results allowed to be used in subsequent papers also without caveats?
Seems there is something other than ‘science; in operation here.
Dave Andrews (14:02:03) :
“10 years on Dr Briffa says he and his colleagues are working to improve the robustness of the results showing that tree ring data reflects climate change!
”
And he is also admitting that the ‘science’ is not yet settled!
Peter Plail. Couln’t agree more about RC. I thought just the same about the mindset of both the people who run it, and many of the contributors when I contributed once. There was one, dghoza, or somesuch, who posted some very odd comments. Schmidt also had some very strange reactions to things. I came away thinking it was a peculiar place to be. I can imagine what they’re like in real life. God, the internet seems to attract them! I suppose we should be thankful these people aren’t walking the streets at night.
Scott Mandia beclowns himself by using an official AGW talking point issued a few months back. “You think there is a huge conspiracy amongst climate scientists. That’s crazy, so you and all of you other deniers are crazy!” Read the fine print on the label, Scott, that smear is to be used on the converted or the apathetic, not a crowd of educated and motivated Deniers.
I’ll tell you what’s crazy. Crazy is not expecting anyone like Anthony Watts or Steve McIntyre to appear when you started down this road. Crazy is thinking that you have made a strong enough scientific case to cause western democracies to cripple their economies with trillions of dollars in taxes. Crazy is thinking that the never ending arrogance and contempt shown towards us by the likes of The Team, Tamino, Romm and the rest of you haters would actually help to Save the World.
“And, of course, as everyone might guess, Gavin censored the comment – as he always does when he has no answer for something or when he finds it embarrasing and inconvinient.”
For what it’s worth, I liked your comment Tilo. And I too have made civil, relevant comments on RC and similar blogs which were deleted or edited to distort my point.
I don’t bother commenting on those sorts of blogs anymore. But it’s fascinating how folks like Gavin, who think they are scientists, have wandered so far away from science.
My opinion only.
P Wilson (12:22:36) :
The most important factors to tree ring growth are nutrients, c02, temperature, competition, and water.
But not in that order, you have the dominant one last.
I’m lost.
I’ve been trying to follow the logic of the tree-ring based hockey stick but it doesn’t make sense and I see that some other commenters are confused as well.
Briffa’s yamal analysis seems to show an approximately 1.5C increase in temperature during the 20th century. Did actual thermometers also show a 1.5C increase during that time period for that region (at least during the summer)? If yes, then what does it matter what trees were used during that period – it matches so you get the same result whether you use tree rings or thermometers. If no, then doesn’t that reject using either those trees or those analysis techniques or both? In which case why would such a paper even be published? And if it rejects using those analysis techniques, wouldn’t that reject the entire chronology?
Why does tree-ring based temperatures having any use in the 20th century except as a sanity check on whether or not trees can ever predict temperature?
I can’t imagine why this seems like a big deal to everybody (both sides). It makes no sense to me.
“jlc (12:47:02) :
If I understand Leif correctly, he is saying that treemometry is nonsense. I think you would be very hard pressed to find an engineer who who would believe that there is anything but a very coarse link between tree ring thickness and temperature.
Perhaps I would be a tad gentler [although not my strong side] and say that the link is not understood [rather than ‘nonsense’] and that it therefore must be used with utter reserve and caution, and that research on its potential usefulness is important. However it is used, there must, of course, be transparency and disclosure”
Quite right, Lief.
“My colleagues and I are working to develop methods that are capable of expressing robust evidence of climate changes using tree-ring data.” – Briffa
“Did he really mean to say this?” – imapopulist (13:42:37)
Ah, but don’t forget that since the recasting of “global warming” to “climate change” Briffa’s statement above is okay. He could simply be measuring natural climate change versus man-made. But I think we all know where the CO2 blame will end up, anyway.
@ur momisugly Scott A. Mandia…
“Hasn’t anybody here wondered why the hockey stick shape keeps appearing regardless of proxy and study author? Perhaps it is a real phenomenon? To suggest that it isn’t implies that scientists are colluding or that every proxy analysis technique always results in the same shape. ”
This is classic group-think. NASA said something very similar about foam-impacts on the space shuttle. A paraphrase might go something like this, “Hasn’t anyone here ever wondered why we’ve never lost a shuttle despite all the evidence of ice/foam strikes on the shuttle? Perhaps it is not something to worry about? To suggest that it is something to worry about implies that scientists and engineers are colluding…” Of course, we know how that turned out. Unchecked Group-think in that case led to death for 7 humans.
So please restrain yourself; bite your tongue; pinch your ear whenever you find yourself suggesting that we should stop questioning data. Doing otherwise is contributing to a perversion of science that leads to problems.
” Crazy is not expecting anyone like Anthony Watts or Steve McIntyre to appear when you started down this road. Crazy is thinking that you have made a strong enough scientific case to cause western democracies to cripple their economies with trillions of dollars in taxes. Crazy is thinking that the never ending arrogance and contempt shown towards us by the likes of The Team, Tamino, Romm and the rest of you haters would actually help to Save the World.”
[snip]
All this debate brings to mind the following:
WHY MOST PUBLISHED RESEARCH FINDINGS ARE FALSE, by John P. A. Ioannidis.
Find the paper at:
http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.0020124
At the link, near the mid/lower right of the page, are links to papers that build on the above author’s paper.
“My colleagues and I are working to develop methods that are capable of expressing robust evidence of climate changes using tree-ring data”
Sounds to me like Briffa’s saying “we’re working on a means to ignore all other data, which would then make the selected data favor our bias”. Either that, or wants to make a merely good story. I was kind of hoping debunking would be a little more challenging than that…
Bret:
“Why does tree-ring based temperatures having any use in the 20th century except as a sanity check on whether or not trees can ever predict temperature?”
As I understand it, that’s the precise point. The sanity check fails in all but a handful of trees.
By cherry picking a tiny number of trees Briffa found the hockey stick shape which he and the warmists wanted (to suggest that recent temperatures are exceptional) but only by ignoring the vast majority of trees in the area which showed little or no similarity to recent temperatures.
The fact that so many trees don’t match recent temperatures suggests strongly that trees are a poor, at best, way of gauging past temperatures.
If trees are a poor indicator of past temperatures then their use as such in numerous AGW-supporting papers is indefensible and much of the “evidence” for AGW crumbles.
(Please correct me if I am wrong, folks.)
Bravo, Ken Hall! Your arguments get to the core of what is wrong with the ACW fiasco. There are so many urgent environmental problems that are being exacerbated by the political choice to focus on a non-existent problem. Overfishing and the balanced use of marine resources especially need more scientific attention, but some fisheries scientists have attempted to deflect criticism from poor management decisions by appealing to unforeseen climate change as the cause of recent fish stock collapses. “Global warming” or “climate change” offer a scientific “cop out” for other problems we are facing. Somehow, we have to get the focus back on the real
challenges that are facing humanity and our earthly home. So many of the proposed measures are only going to increase our true “environmental footprint”, and at what a cost to human life!
Briffa and his ilk need to consider the consequences of their use of shoddy techniques in support of their current paradigm. A sample size of ten trees! I think we learned better as science undergrads. Thank you Steve McIntyre for your persistence in pursuing the evidence and revealing what actually was done.
brazil84 12:20:50
Oh, no, I meant Scott Mandia was projecting.
===========================
There seems a lot of personal dishonesty, fraudulent in it’s intent.
What happened to President Trumans “The buck stops here”. Though in England it might just be a bucket of urine!
Here here Ken Hall !!! well said.
@Bret (14:24:18) :
“I’m lost…
I can’t imagine why this seems like a big deal to everybody (both sides). It makes no sense to me.”
At this point, and I mean no disrespect to any of the major players in this situation, this is a scientific contest of wit of the purest kind. The effects on our understanding of climate due to any form of resolution of this issue will be so minor as to be meaningless. This is true in most sciences when arguments get to this point, so again my apologies to anyone who feels I’m peeing on their interesting work, I really am not trying to do so.
The reason this is a big deal is simply and plainly because one group of people made claims. These people published in scientific journals and in official government reports while being paid with taxpayer dollars. Some of them even became outright activists esposing their views that their research was supposed to back up with evidence… However, it is now clear that the scientific backing for any claims made by these people is unknown at best, and outright fraud at the unthinkable worst. Presuming that it is simply an unknown, then there is still scientific misconduct going on because if you are truly a scientist and you make claims, you are honor-bound to share and discuss your data and methods for making said claims. These sorts of fencing battles between minds occur in many fields in science when there is something that is truly unprovable, and they generally resolve themselves when more data becomes available.
Again, as far as our understanding of climate is concerned, this is almost a non-issue. However, as far as accurate representation of available data is concerned particularly in the highly-publicized IPCC reports, this is huge. This is frankly a battle over propaganda fought with the rapier of scientific method. I don’t know of many times in history when this has happened in such a public fashion. The battle over evolution in schools was one, Copernicus’ fight over his work on a heliocentric solar system was another.
Dr Svalgaard has a point about Dendrochronology and the use of such data for temperature proxies. Even at the point of collection, the radial sample cores may not give a complete picture of tree ring growth because very few trees appear to have perfect tree ring symmetry. Even averaging out a great many samples would still leave a very wide margin for error.
I’m also pretty dubious as to how tree rings can translate to an accurate measure of temperature to 0.1 of a degree. Surely you get maximum tree ring growth under what are ideal conditions for a particular species, but those ‘ideal’ conditions cut across a fairly wide gradient of rainfall / environment / temperature and do not correlate well to temperature alone.
someone please enlighten me – didn’t steve exclude the briffa 12 and get a serious drop in late term growth to below average – and didn’t steve then also do another graph with the briffa 12 added back in that yielded a flatline?
if so then isn’t the briffa accusation about removing them rather hollow – not just totally hypocritical????
Bottom line is that the entire dendro scheme is highly questionable at the very best and downright fraudulent at the worst. With this team, I expect the worst.
Isn’t it just amazing that the entire field of climate change was resting on just 10 or 12 trees! The whole temperature record for the last half of the 20th century was a few trees, and now we know it’s all wrong!