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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Scott Mandia 11:11:39
Man, Scott, didya notice I gave you a big clue at the Examiner, that this is not a conspiracy, but a ‘Popular Delusion and a Madness of the Crowd’?
======================================
I believe we’ve discovered an answer to the ancient question, “Does a bear crap in the woods?”
Ans: “Right at the base of YADO61!”
Briffa wrote;
“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.”
My own response;
Erm, so the 20th century temperature highs recorded in the mid to late 1930’s didn’t happen then? Put in historical context there appears nothing unusual enough in the late 20th century temperature record to justify the postulation of runaway global temperature rise.
“I did not say EVERY reconstruction is a hockey stick. :)”
You pretty much implied it when you claimed that “the hockey stick shape keeps appearing regardless of proxy and study author”
The fact is that the hockey stick DOES NOT keep appearing regardless of proxies and study authors.
“BTW, I do not drive a BMW nor do I live in a big house. 🙂
Most of the researchers are just like me regarding demographics”
Again you are attacking a strawman. The fact is that climatologists are receiving enhanced funding, attention, and prestige as a result of concerns over CAGW. This is true even if they are not getting fancy cars or big houses.
£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
Wow – over a million bucks for nonsense “research”.
“BIG OIL” is not paying me nearly enough!
brazil84 11:31:48.
You think warmist strawman, and I think projection. Hey, we’re both right.
brazil16, too, for the symmetry. er, summitry.
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Tim Clark (10:58:14) :
But the statistical contortions leading to erroneous conclusions drawn from a few scrawny trees really [snip] me off. These people have no concept of any facet of plant physiology.
And that is my point. One can lament the cherry picking and the sloppy stats [can find some of that on both sides of the fence], but the public will see that as bickering rather than science. To make a scientific point one has to attack the base of it all: that assumption that tree-rings are a good proxy for temperatures.
DonK31 (11:15:09) :
The problem, to me is that those trees are the justification for trillions in increased taxes and increased control of the people by their “betters” in government.
And that is even more reason for doing the ‘attack’ right.
Bernie (11:15:49) :
I saw the data the same way Leif did: All 10 trees show a warming trend – though YAD06 appears as an outlier in this very small sample. […] I think Steve’s whole argument is that a lack of transparency with respect to data and methods is bad for climate science.
Transparency is a must, but if it is true that tree-rings are a lousy proxy then transparency doesn’t matter. I can photograph the tea-leaves I use for sunspot prediction and produce the photograph for all to see and even send in the leaves to an independent lab for verification that these are genuine tea-leaves.
The ‘attack’ must [also, and primarily] be on whether trees are any good for this.
Really interesting;
Yamal peninsula is really quite near the location where the ‘Tsar Bomba’ was detonated on October 30, 1961. Some 450 km (and maybe 1000 km at it’s farthest point) from the Yamal Peninsula, Novaya Zemlya was the sight of what has been described as the “most physically powerful device ever utilized throughout the history of humanity” (Wiki). The bomb was detonated at a height of 4 km, creating a fireball some 8 km in diameter. It is stated that some 5.25 x10^24 watts (yottawatts) of energy were released, a figure equivalent to more than 1% of the sun’s power output.
At a distance of some 500+km, the radiation would’ve been largely (though not entirely) dissipated, but significant fallout as well as physical effects would’ve reached Yamal, especially on hills with an easterly exposure. Above ground testing at the site began in 1954, ended prior to the test ban treaty in 1963, although subsequent underground testing took place at the site. Seismic activity attributed to this underground testing set off an avalanche which blocked a stream, creating a lake 2 km long.
Now, I’m not saying that Tsar Bomba created mutant growth trees, hell I’m not 100% certain whether the trees being looked at were on the Yamal Pen., or if they were in Yamalia, a bit futher away. What I would say is that if these trees were on the Yamal Pen., they certainly felt the effects of this if not many more bombs. The effects were felt as far away as Helsinki. Flash heat could’ve created glacial pools, or otherwise created an improved water supply, there could’ve been other ecological effects as well. This could’ve been the most unique ‘UHI’ ever to effect the surface T record.
To that end, why did this one tree take off about the same time the above ground testing started? Is there ‘meta-data’ on the actual tree? Grid coordinates, elev. and facing, exposure data, etc.?
Just a wild hare when I realized where this Yamal Peninsula really is, knowing full well where Novaya Zemlya was.
Curious.
jlc (11:55:11) :
What’s your point, Leif?
See my comment (12:09:52)
“Lucy Skywalker (11:35:30) :
Michael (10:03:34) : 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, we are all sheeple to some extent… until we go and investigate for ourselves.”
Lucy,
I admit I am a sheeple on many issues, that’s why I stand open to be corrected with the facts presented to me. That’s also why I believe nothing I read and half of what I see without much thought and scrutiny. I’m a slow reader for a reason.
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
OK, Leif – I see your point and I apologize.
Sometimes you’re a bit too subtle for me.
jlc 11:55:11
Heh, I’ll bet Leif understands the significance of all this. He’s got two bob both ways because his neutral status insists upon it. It would not be consistent to bet otherwise.
====================
(and yes, I was being intentionally obtuse with regard to the use of the term ‘meta-data’, so go ahead and consider me crazy, and even simple, but at least recognize my wry wit rather than assume ignorance)
Here we see the artful application BS using science laden language. BS should be the call letters of our times. The news today should shout when BS is not used to explain “fill in the blank.” Lots of verbiage but no key question addressed. What a genius.
“You think warmist strawman, and I think projection. Hey, we’re both right.”
I’m not sure what your point is. 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.
So what’s there to project?
rain tends to bring the temperature down and during long hot summers, aridity can cause a drought problem. Saying that higher temps correlates to temperature is quite a simplification. Tree growth responds very well to c02 on the other hand. The most important factors to tree ring growth are nutrients, c02, temperature, competition, and water. If you have high atmospheric c02 and plenty of water with moderate/average temperature, then you have greater tree growth than high temperature, low c02, (which is what the pre-industrial average is supposed to be) and drought/aridity
Gavin trots out the line about peer-review despite having ridiculed the peer review process in a very recent post because something was published that he didn’t like. Always the double standards. At least peer review of Steve’s work is actually possible whether published or not. It wasn’t possible with Briffa’s work.
And Leif, the tree-based hockey stick is only important because it keeps being trotted out in IPCC impacts or FAQ publications to scare the public: Not the newer HS by Mann with the MWP, nor the spaghetti graph HS of the main IPCC reports. It’s always that utterly discredited MBH98 they use again and again. Gavin even drags up in his latest post, despite it being superceded by Mann’s own latest work. If they’d just disown it then we could all move on.
Just started reading “The farce of Physics”: A good reminder that climate science isn’t exactly alone with this poor behavior. In fact they are highly representative of mainstream scientific practice.
addendum mistake: “Saying that high temperatures correlates greater precipitation”
My opinion of Briffa’s rebuttal – http://www.di2.nu/200910/01a.htm – not too disimila methinks
jlc (12:13:23) :
OK, Leif – I see your point and I apologize.
Sometimes you’re a bit too subtle for me.
Perhaps just a bit less emotional about it [since we are not on the topics of barycenters and non-cosmological redshifts 🙂 ]
addendum: mistake. should read: saying that greater temperatures means greater precipitation
Leif:
“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.”
I think that we would all accept a result that showed a small rise. It’s the sharp rise that results from the methodolgy and the one tree that are the issue.
Leif, if you are still here, I’m dying to get your take on the Svensmark cosmic ray theory. Pretty please with sugar on it!
Leif:
“Transparency is a must, but if it is true that tree-rings are a lousy proxy then transparency doesn’t matter. ”
Completely agree. Briffa’s own notes on the divergence problem of the second half of the twentieth century are an indication that he knows also. What I don’t understand is why he thinks that the problem is only limited to the second half of the twentieth century and only to the northern hemisphere. My guess is that that kind of divergence can happen anywhere at any time.
Then there is the question of the other proxies. It seems like the tree rings have recieved the most scrutiny. Can the proxies that have not recieved that level of scrutiny be trusted?
Leif,
the raw data and processing would greatly help in showing whether it is viable or not, wouldn’t it?
Leif,
Big picture I do agree with you. But I do see this as useful to that endpoint.