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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I have been designing and building dams for more than 40 years, so I have an obsessive understanding of recent “climate”:
I am an engineer, like many CA and WUWT readers. Most engineers, look for proof, justification, evidence, logic, common sense, etc. As Steve Mc says, this is the engineering method
If I understand Lief 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.
The reason I take the time to comment on this is that so many people (even engineers) accept at face value the publicised claims based on very tenuous science.
In general, engineers are the most honest and cautious members of any society.
We have an obligation to keep ourselves informed and to speak our minds
Step one: denial
Step Two: Anger
Step three: negotiation
Step Four: Depression
Step Five: Acceptance
The AGW `s are in the second step …
have to give time to them …
Leif:
We seem to agree, but given that the going in assumption is that old tree rings are acceptable as temperature proxies isn’t transparency needed in order to determine the validity of pre-instrumental trees as thermometers? The measurement issue is their value in estimating trees before thermometers relative to other proxies.
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.
Leif; while I agree that over the full period, all of the trees show an increase. However, 4 of them show a peak temp prior to 1950, while three of the remaining show peak temp prior to 1970. Further, over the last 50 years, very little actual trend can be inferred from any of them; even the most extreme example demonstrates that it was warmer at the beginning of the period than it was in 1990, and didn’t get significantly warmer during the interim.
Further, only one of the ten shows temperatures at 1990 were above the highest temp from 1900 to 1950. Only six of the ten show temps at 1990 above all temps prior to 1900, a period that concluded what is commonly regarded as the little ice age.
If we’re not arguing about AGW as caused by CO2 emissions, if this is only climate change we’re discussing, then the whole debate needs to end, so it can begin anew, without an agenda, and without a predetermined root cause, and without the fascist power grab that is IPCC, without cap & trade, and without the impending EPA and state regulation of what is, after all, the life breath of plants, and the normal and very natural byproduct of animal life.
Whatever effect a CO2 increase has on temperature, it’s most significant during winter and in the coldest places on earth. At other times, and in other places, the amount of energy absorbed by CO2 is not only small compared with the total energy flux, but is also swamped by water vapor.
So I ask you, Prof Briffa, why summer temperatures?
The frustration dripping from the RC rebuttal is funny. If they were so sure it’s “irrelevant” they wouldn’t have to resort to putting up a lot of uncorrelated pictures. Apparently there are so few usable graphs that even a graph showing CO2 over last thousands of years is needed to discuss the hockey stick that is supposedly present in temperature the last few decades …
The hockey stick is a marketing ploy. It helps people believe they are responsible themselves. You can try to stretch the dramatic rise as much as you want eventually it either needs to be really noticeable or people will drop the faith. It’s like how several religions predict the end of the world, you can “delay” it a few times but it soon becomes rather obvious that it’s not gonna happen.
Mike Bryant – I’m with you all the way and would value an explanation of why proxies are used for recent times.
I understand why temperature proxies are of value when looking at the past before real measurements were available, but what is the reason for using temperature proxies for the last couple of decades when the real thing exists.
OK, we have had many discussions here about the possible inaccuracies of modern temperature measurement, but surely they are likely to be more accurate, almost by definition, than proxies, since I assume that at some point in time actual temperature measurements are used to attempt to”calibrate” tree ring data.
And why choose trees in Siberia? Has Siberia become a proxy for the whole world.
Wikipedia says about reconstructing a temperature record of the last 1000 years ” A reconstruction is needed because a reliable surface temperature record exists only since about 1850. ” So what possible justification can there be for using proxies after this date.
Forgive me if this is too simplistic but my brain is hurting.
It seems to me that, at the moment, the entire edifice of US and European environmental and economic policy if balanced precariously on a few Siberian treestumps.
I know the ‘hockey stick’ issue is important……but I can’t help thinking it might have been better if the tree-ring research had been carried out on cherry trees somewhere in Surrey…..at least then, ‘cherry-picking’ would have been an acceptable part of the investigation…even expected! With the added bonus of an abundance of hockey sticks in the local vicinity.
Oops.
One key element here is that Dr. Briffa did not archive the data for 9 years until he was cornered to. Why? Once archived for all to see, the limitation of the data (picked by the Russians, small subset etc…) would have become readily apparent, not only to their “nemesis” but most importantly to ANY OTHER Paleoclimatology research group. Therefore the focus of RC reply on McIntyre is indeed misplaced imo.
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Bob Kutz (12:10:47) :
Yamal peninsula is really quite near the location where the ‘Tsar Bomba’ was detonated on October 30, 1961.
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Hmmm … it seems there would be some sort of isotopic signature in the rings.
As you all know by now, the crew at Real Climate are in a rage. But Gavin posted a response to Steve McIntyre and in the comments section he made the comment that everyone was getting all of the data that they needed. So in response to his comment I submitted this comment.
http://2.bp.blogspot.com/__VkzVMn3cHA/SsUMIzGbPXI/AAAAAAAAAFI/3o4j7swEoDA/s1600-h/Briffa_Yamal_RC_screen3.JPG
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.
Bob Kutz (12:10:47) :
Very interesting, and it’s yield was sustained for 30 seconds.
What were the other trees around YAD061 like? New trees, dying trees, diseased trees, burned trees, logged trees , etc?
A tree in a grove that suddenly has access to the the majority of the resources can take off.
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.
I am guessing that he is hiding behind the “not yet published” data because they have not managed to discover any more magic trees yet.
“My science is robust dammit and as soon as I find another 10 trees that back up my religion, I will publish!!!”
He asks why did McIntyre remove those 10 trees?
WHY? well that rates a deserved “well DUH!”
How arrogant and indifferent to your fraud do you have to be to not realise that he did not publish them because they are NOT a representative sample and they falsely skew the results of the temperature record. They are anomalous. They are a fix. They are a CON!
I was waiting for a serious and substantive rebuttal. I should have known better.
Carbon induced climate catastrophe is a serious fraud. Let us all stop wasting incredibly precious time, money and energy attacking the production of an essential trace gas that is necessary for life to flourish, and start, finally, to get a solution to the real and serious environmental catastrophes in deforestation, habitat destruction and wanton chemical pollution. We need to clean up the “trash island” in the Pacific. We need to stop hunting and fishing species to extinction and we need to stop cutting down huge tracts of ancient historic and irreplaceable forests.
It is sickeningly perverse that the Urang-utang is on the very cusp of extinction because climate alarmists and environmentalists have boosted the demand for bio-oils that are planted where these magnificent animals used to have a habitat. It is gut wrenchingly hypocritical of them and I am incensed to a level of frustrated fury every time I think of it. How DARE they lecture and legislate and waste billions of dollars pushing a lie, when the environment is being raped in so many places? Often BY THEM!
Environmentalists are some of the worst environmental vandals in the world and they are desperate to keep us distracted with the fraud, the rubbish that is carbon alarmism.
We should have NONE of it!
Go sick ’em Anthony and Steve. Sick ’em good and proper!
Nice hair style Keith, like it!
Bob Kutz (12:53:04) :
Leif; while I agree that over the full period, all of the trees show an increase. However, 4 of them show a peak temp prior to 1950
which was a warm period,1930-40s…, so in that respect the proxy doesn’t look that bad…
Peter Plail (13:09:14) :
As much of the tree ring data I have looked at where there is a record back 2000 years, what shows most is the precipitation, and the temp is inferred from there (uncertainty rises).
Comparing such record to the instrumental data, one comes away with the impression that tree ring is generalized for precipitation, and over very long timespans give a rough impression of temperature.
What stands out in tree ring data are the exceptional years, like deluges and hard droughts, and they line up nicely with instrumental.
As for eras, long periods such as LIA and MWP, RWP are in evidence.
Scientist are getting good at sounding like politicians. To bad I seek out science to take a break from politics.
“And why choose trees in Siberia? Has Siberia become a proxy for the whole world.”
I think that choice is defensible. Harsh conditions (high altitude, far north) are good for producing old trees. Sparser trees, less fire, less diseases, less parasites. Also, when you use fossile trees from near the tree line and on south flowing streams, you have less chance of having a tree wash in from another location.
Dr Briffa says,
“He offers no justification for excluding the original data”
This is desperation. I strongly suspect Briffa knows that the original data was excluded because it was the basis of several of his publications claiming to show a hockeystick effect and excluding it is a reasonable way to determine if he may have cherry picked data in such a way as to create a hockeystick. His response is bluster.
“My colleagues and I are working to develop methods that are capable of expressing robust evidence of climate changes using tree-ring data.”
Did he really mean to say this?
Would others in this field of science agree that this is an appropriate objective?
Am I living on an alternate planet where logic and reasoning is distorted beyond my comprehension?
This may be off topic but the Chinese must be laughing their heads off, and, shaking their collective heads in utter disbelief as the free world unravels over the readings of basically one tree. Here they carry most of the States dept, are on the verge to put man on the moon, are fast becoming the worlds number one super power while the free world may go into a financial death spiral chasing tap and trade and green energy.
North America could be energy self sufficient, but blocked by an unproven science, just amazing!
Leif Svalgaard (10:51:04) :
hmmmm (10:01:51) : and others
I’d guess because people want to replicate the damned study and keep getting stonewalled.
It would seem that the effort should be directed towards the general utility of trees. If it can be shown they are no good [“hundreds of other reasons”], then the various stonewalling etc doesn’t matter anyway.
The STonewalling does matter because it is the modus operandi of a clique which seeks to advance it’s cause and ‘move on’ before it’s suspect data practices are discovered. Having moved on they can tell us ‘it doesn’t matter’. Thus we are led in a Gish Gallop towards the final destination – the self policed parade of carbon sinners in atonement.
However, I agree that showing that allegedly good treemometers are a rare species which don’t tell us anything beyond the coincidence of their growth pattern and the instrumental record would be a good move.
More Yamal tree ring temperature data: this data is flat as roadkill
After that post I’d be very fairly certain that whatever tree growth rings measure, it isn’t temperature. Certainly not without being confounded by other variables.
I only ever met one tree growth ring expert and that was back in 1976 or 77. He was using them as a proxy for rainfall. The issue under discussion was the Boulder dam which was justified on 40 years’ worth of data. After the dam was complete the quantity of water has never since matched the prediction. His tree growth rings showed that the 40 years were the wettest in the last 400 in the catchment.