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.
Sponsored IT training links:
Guaranteed success in NS0-154 exam with help of 650-177 practice test and up to date 642-515 exam dumps.
Listen guys, if you have some personal vendetta against Briffa then fight it out, I do not care. But this does nothing to further the discussion. I mean, “so what?” It does not make a bit of difference to the accumulation of evidence that points to a significant increase in warming during the past part of the 20th Century. THAT is what we need to address. If he made a mistake in his paper then do what everyone else does. Put yer money where you mouth is and publish; not on a blog (however worthy) but in a good journal where good brains can also dissect your work. In short, if you want to play with the big boys, play by the same rules.
Supercritical (01:14:41) :
1. Re Nasif’s post, can anybody explain how Dendrochronolgists correct for this presumably parabolic characteristic , i.e. that tree-ring widths can indicate both very high and very low insolation, and hence temperature, at the same time?
There is not a methodology for doing the distinction, nor for knowing if the less growth was due to high insolation (more than 50%) or to poor insolation (below 50%).
At boreal regions there are good days of insolation (near 50%) but cold (less than 23 °C). The treerings would widen, but not by the effect of temperature, but by the amount of insolation. Then, the graphs of temperature wrongly plotted from treerings always show off even temperatures. If the grapher add the instrumental data, the result is always a Hockey Stick.
I combined four databases from different proxies, including China and Russia databases, and the result was in accordance to MWP and LIA. The graph revealed that the warming in the last decade (1990-1999) was not relevant in the whole picture.
You know this is a big deal by the amount of AGW cheerleaders coming on here to defend Briffa (this is the most I’ve personally seen on any one comment thread).
Apparently, Briffa has been at the center of an influential group of AGW scientists.
It must be felt that if Briffa is found guilty of “cooking the books” in the court of public opinion, the whole “science” of climate modelling will be thrown into doubt.
Yes, “holding up the scoundrel” in the course of conversation is a good “show stopper”.
Well here’s my two pennethworth. I do not know Mr Briffa, I am sure he is a decent person with good intentions. I hope he is feeling better soon.
However he has put himself in a rather silly position, so I offer some words of caution. The secret of confidence trickery,[snip], is to never tell the whole truth, & never tell a complete lie. One must intersperse these two enemies equally. That way, your gullible victim will be spending so long figuring out what is what that in the meantime you walk away with the prize! It is just the same in science I fear, by withholding evidence significantly long enough to allow crucial decisions to be made without thorough analysis of said evidence, after which release of evidence becomes pointless & literally, academic. I believe such action is illegal in most countries where the law is concerned?
As a scientists myself, I am comfortable to withhold judgement until the details have been thoroughly flushed out.
Steve’s analysis has brought up a significant question. The question itself is not near as important as the answer. To Briffa’s credit, he says he and his collegues have not had a chance to view Steve’s methods. Suffice it to say, I have a feeling that noone in the skeptic camp has either, but instead, just accept what Steve is saying based on a preconditioned stance.
In Science, it is not becomming of us to take sides in an issue. Steve’s methods, and what he did, deserve as much scrutiny as Briffa’s. Steve has shown to be an straightup kinda guy, and always makes his methods and data available, which is a plus for him. While the team has not been as forthcomming, the “team” is allowed to defend their methods as well. However, I will agree, it is not the “teams” place to also be the judge.
In the end, the real issue for me as a scientists is the issue of transparency. It’s refreshing to see that pertinent data is finally being made public and available to scientific scrutiny. Hopefully Jones will take a cue and cooperate in the future as well.
In reading Steve’s original post, and as pointed out by Briffa, Steve’s analysis was not intended to slap down Briffa, but instead, was a reanalysis that generated questions. We call it “real science”! There are uncertainties to be discussed, methods to be flushed out, which as always, generates more questions. Don’t get me wrong, I’m well aware of the bias that exists in the AGW camp, but we on the other side need not stupe to their level.
*************************
Deanster (07:47:13) :
As a scientists myself, I am comfortable to withhold judgement until the details have been thoroughly flushed out.
***********************
I’m OK with withholding judgment also, as long as climate legislation is put on hold as well.
************************
Steve’s analysis has brought up a significant question. The question itself is not near as important as the answer. To Briffa’s credit, he says he and his collegues have not had a chance to view Steve’s methods.
****************************
Without Steve’s question, there would be no need of an answer. Steve laid out what he did already. It was pretty simple. What other information is there to be had?
**************************
In the end, the real issue for me as a scientists is the issue of transparency. It’s refreshing to see that pertinent data is finally being made public and available to scientific scrutiny. Hopefully Jones will take a cue and cooperate in the future as well.
*************************
Ten years is a long time. Why didn’t the R.S. catch this before it was pointed out to them? Why have journals become so sloppy?
Peter (13:00:51) : So I ask you, Prof Briffa, why summer temperatures?
My guess is that summer is the growing season, so whatever influences growth happens in the summer. Briffa is exposing his temperature fixation as the only possible ’cause’ for enhanced growth.
I think what he did was get data that supported his hypothesis going in and so he simply didn’t question it enough. Now he is stuck defending it or admitting he screwed up major and with the financial and political cost of admitting the mistake he just isn’t willing to do it.
Scientific method have a tough fight when a man’s family and their well being are on the line.
Scott A. Mandia – Scott, you mentioned bore holes. In looking at your reference to the sunysuffolk borehole_3, why do I not see any correlation to long term temperature data (250+ years), say from east England, Uppsala, etc.?? Here is a hint to look:
http://rimfrost.no/
In fact if you average up a lot of those long term temps you come up with a relatively flat curve, with the usual ~60 year cycle.
As far as talking down to “non scientists”, I happen to have graduate degrees in engineering, along with several patents in thermal systems. This includes modeling in non-steady state conductive, convective and radiation effects.
The fact the “hiding” (not making it available) of data to get you view across is the point of this series of posts. Try not sharing data in many companies and you will end up out the door in short order. The secondary part is that if we look at the tree ring data, it looks pretty flat, aside from what appears to be normal bump and grinds.
At least at this site all comments are posted. Try going against the grain at RC, and you don’t even get a voice. If AGW is all that settled, why try to “muzzle” those who question it?
Anthony asked me to make an apology and that is why I am posting this comment.
There has been serious cancer in my family (father-melanoma, brother – cat 3 brain cancer, mother – brain tumor) so I am well aware of the issue. I chose cancer as the ailment because it is a well known serious condition that must be treated immediately. That seems to me to be an appropriate analogy to the dangers of climate change and the various choices we face.
IN NO WAY WAS THIS INTENDED TO BE INSENSITIVE TO DR. BRIFFA’S CONDITION. I SINCERELY APOLOGIZE TO HIM OR TO ANYBODY ELSE THAT WAS OFFENDED.
Now I ask for fair play. To Anthony W, Steve M, and everybody else who has been directly or implicitly calling Dr. Briffa a cheat or a fraud while he was too sick to respond to these false allegations, you owe him a public apology.
Step up to the plate, folks.
Scott Mandia hasn’t yet replied on the TWO different versions of the Yuang & Pollack papers yet. In the original they inferred from heat based borehole data that the MWP was warmer than today. This was later revised, and is the version that he posted earlier in which the authors merged the instrumental temperature record with the borehole data.
they also mention the limitations of borehole data for temperature proxies. ie: one cannot super-add proxies to a temperature record
Also, the graph he extracted was fig2 from the paper. Fig 1 shows something else entirely with the same data set, but different time series.
In the original paper of 1997, the did not merge instrumental termperature records from the 20th century and came to an entirely different result for present-past temperature proxies
Scott Mandia, Maybe you could comment on this quote from the authors of the recent Woods Hole SST reconstruction from the Indonesian warm pool:
“The more interesting and potentially controversial result is that our data indicate surface water temperatures during a part of the Medieval Warm Period that are similar to today’s,” says Oppo. NH temperature reconstructions also suggest that temperatures warmed during this time period between A.D. 1000 and A.D. 1250, but they were not as warm as modern temperatures. Oppo emphasizes, “Our results for this time period are really in stark contrast to the Northern Hemisphere reconstructions.”
http://www.whoi.edu/page.do?pid=7545&tid=282&cid=59106&ct=162
anna v (06:01:25) :
Scott A. Mandia (03:31:13) :
I refer you again to the icecore record: temperatures during the holocene are oscillating within +/- 1C on a slightly downward/cooling slope. Oscillating behavior allows rates to change too, on the upside and on the downside. example: Take a sine curve . The derivative is a cosine curve, and that is the rate of change, which is not constant of course and can be as big as the maximum change.
Dear Anna V., That figure is too short. The oscillations during the Holocene are within +/- 3 °C for a total oscillation of 6 degrees.
If indeed the generations of chronologies since Briffa’s Yamal all have the same DNA, it would seem we’ve been swindled, and some industrious journalist need to dig out all the details for someone like Bishop Hill to summarize for laymen (such as myself) and all policymaker to read. Meanwhile, as we wait for the political shakeout, there are plenty of us who are actually quite curious about the science.
Since there are clearly two distinct, equally capable “sides” to this issue (Briffa and McIntyre), and both disagree about the efficacy of what the other spliced onto the sub-fossil record, how about the following experiment: “teams” from both sides select an acceptable subset of trees from any northern Urals or Yamal forest, have an “approved” dendro expert accompanied by Steve or Anthony, (any sceptics with time on their hands) to the Yamal (can’t wait?); gather an approved number of new rings. Analyzed them in an approved setting using an agreed-upon method, making all data available online. Splice them onto the old record with an agreed-upon method. Publish. Make headlines. “Staunch adversaries come together to form unprecedented compromise…” and all that.
This controversy will not kill off dendrochronology, much to the disgruntlement of treemometrites. But one might hope for some better dendro records and practices as a consequence.
Don’t know if anyone will read this far down, but here is my take
Briffa was attempting to dazzle readers with complex statments that most of us will not understand rather than actualy stating why he used only 10 (or is it 12?) trees. Thankfully we have people like SM to set the record strait.
I think Briffa’s reference to “the unusually high summer temperatures in the last decades of the 20th century” is meant to mean that these trees have responded to increased “degree-days” by growth increases.
This is intenable on a number of reasons, some plant physiological;
1)8-sigma increases are simply unbelievable. Van’t Hoff’s rule states that a biological process approximately doubles for each 10C rise in the physiological range
2) No evidence presented of LOCAL summer temperature increases. Any advance on a 30C increase?
and some statistical- as Steve M has so ably shown.
Scott A. Mandia:
Yes, that’s the average, which includes the periods when the temperature decreased. Take away those periods and the rate is much higher.
And how can you be so sure that the current rate is exceptional? Do you know what the rate was for the period 998AD to 1024AD? Or even 1820 to 1840?
I would have doubts about any system that selects such a small subset. Is it less that 50% of the data samples, I haven’t seen a clear statement of how many tree the 10/12 were selected from?
Once Dr Briffa discloses the method to select trees that match a pattern I think a good test would be to see if one can get similar numbers of matching trees (~10) from other patterns using the same method, e.g. can you find 10 trees in this set that match the stock market, price of carbon credits, flu deaths. If you can match 10 trees out of N to any arbitrary graph (or a significant number) then surely it would show they are not suitable as a temp proxy.
@Scott Mandia
“Wrong.”
Wow, that’s quite a rebuttal. The fact is that for some authors and some proxies, you don’t get a hockey stick. I’m happy to give you examples if you like.
Scott A. Mandia:
Can you name, or even number, the scientists who are really telling the world that? And do you really know what the rest of them think?
Scott A. Mandia:
**************************
Scott A. Mandia (08:45:04) :
Now I ask for fair play. To Anthony W, Steve M, and everybody else who has been directly or implicitly calling Dr. Briffa a cheat or a fraud while he was too sick to respond to these false allegations, you owe him a public apology.
Step up to the plate, folks.
***********************
I am certainly sorry to hear Dr. Briffa is ill and I wish him the best and that he gets well soon.
Other than that, I don’t see why anyone owes him an apology over the tree ring articles. He still hasn’t stated why/how he selected the 12 cores and excluded a bunch more. If anyone did call him a fraud, they jumped the gun and should take it back. But let’s see the methodology before we get to any apologies.
Scott. it is a perfectly inappropriate and cruel analogy. You apologise then try to milk it again for every nuance. Lets not go there.
If you’d like to address some of the anomalies in proxy v temperature records and the inviability of superimposing proxies on temperature records instead.
Dr. Briffa is ill and we all wish him a speedy and complete recovery.
That said, he has not, to my knowledge, been too sick for the last 10 years to release his data.
@ur momisugly P Wilson,
http://www.geo.lsa.umich.edu/~shaopeng/2008GL034187.pdf (2008 paper)
Fig. 1 and Fig. 2 use the same data and present day temps are hard to see in Fig. 1 because of the 20,000 year x axis. Fig. 2 just looks at the past 2,000 years so it is easier to see the record. There is nothing sinister here.
In science, it is typically understood that progress is made with subsequent papers and that a paper in 2008 will likely have a greater value than one on the same topic from 1997 assuming the same authors.
I was confused why you would give greater weight to the 1997 paper so I wonder if you are trying to steer toward the “conspiracy” that these authors changed their papers so that they would match the hockey stick. Have you read the link below?
http://motls.blogspot.com/2007/03/borehole-paleoclimate-reconstructions.html
I am guessing you have and that is why you are pressing this issue with me. Of course, if you believe in conspiracies there is nothing I can do to dissuade you that a paper in 2008 by the same authors on the same subject is considered superior. Scientists do learn over time. 🙂