Response from Briffa on the Yamal tree ring affair – plus rebuttal

First here is Dr. Keith Briffa’s response in entirety direct from his CRU web page:

Dr_Keith_Briffa
Dr. Keith Briffa of the Hadley Climate Research Unit - early undated photo from 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.

Dr. Keith Briffa in 2007
Dr. Keith Briffa in 2007 from this CRU web page: http://www.cru.uea.ac.uk/cru/people/photo/keith2007b.jpg

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.

Yamal-Hantemirov-Shiyatov-0_2000_zoomed2
Zoomed to last 50 years - click for larger image

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.

Briffa_single_tree_YAD061
10 CRU trees ending in 1990. Age-adjusted index.

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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pwl
October 1, 2009 8:45 pm

“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.”
Right on target. That’s what I’ve been wanting to know.
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.“
“… was intended to better represent …”
What? That sounds like manipulation. This isn’t a movie or a novel where you get to cherry pick the “representation”, it’s science and you must not use trickery Briffa dude. Besides how the heck are you supposed to know what a “better representation” is anyhow?
I think by represent Briffa might mean to “better allow us to present our biased point of view so that people freak out”, or that seems to now be the effect.

richcar
October 1, 2009 8:45 pm

I really feel that this discussion has been too focused on the validity of arctic tree rings as temperature proxies for or against the Hockey Stick. Although I am a sceptic I feel RC and Scott Mandia are rightfully trying to turn the discussion to the various other methods used in reconstructions on more of a global basis. My definition of the hockey stick is whether the sum of all these proxies really convince me that today’s climate is exceptional or is similar to temps during the MWP. What concerns me the most is that the hockey stick presented in the media does not even closely represent what these scientists are showing us.

Patrick Davis
October 1, 2009 8:45 pm

“bill (20:26:05) :
Patrick Davis (18:45:15) :
For goodness sake have a look at how the CRU is funded. Check how many of the staff are salaried by the UEA. All grants go to pay for researchers and other non salaried staff”
Are you suggesting the CRU, and sub-groups (CCPR), some of which are sub-groups of The Met Office, isn’t, since at least the mid-1980’s, Govn’t funded? That’s a good one Bill, I needed a laugh to start the w/e off. Cheers!
“£226,981: Quantitative applications of high resolution late Holocene proxy data sets: estimating climate sensitivity and thermohaline circulation influences”
Represents about 15 years salary when I last worked in the UK. That’s what I call a good wicket.

savethesharks
October 1, 2009 8:57 pm

John A (20:31:07) : “If Keith Briffa had not replied because of his health problems, I would have understood. But the fact that he could respond so quickly while ill throws a spotlight on his obstructive and uncooperative behaviour over the last ten years while healthy.”
The cold, hard truth. Wishing Dr. Briffa health and wellness….but this inconsistency is unavoidable.
Especially when your research is leveraging the entire world right now [even though Carbon Credits are not looking too good right now on the CBT].
Chris
Norfolk, VA, USA

savethesharks
October 1, 2009 9:03 pm

richcar (20:45:19) : “Although I am a sceptic I feel RC and Scott Mandia are rightfully trying to turn the discussion to the various other methods used in reconstructions on more of a global basis.”
No.
“Rightfully trying to turn” in this case…is seen as an excuse for creating a strawman.
They need to produce the evidence of those “reconstructions.”
Chris
Norfolk, VA, USA

Jeremy
October 1, 2009 9:13 pm

Caleb,
Nice post – thanks. Sometimes it takes someone without a lifetime dedicated to academic sophistry to state the darned obvious: “the emperor has no clothes”.
In one foul swoop, Dr Briffa has killed the “science” (if it can be called that) of tree ring reading deader than a dead dog’s bone buried down a blind alley off a dead-end street in a ghost town!
Hip Hip Hooray Tree Cheers for Dr Briffa.

Pragmatic
October 1, 2009 9:19 pm

If we use the recent crashed Carbon Credit Market price of 10 cents per ton of CO2 – as a proxy for acceptance of Anthropogenic Global Warming – AGW is in serious trouble.
The plummet in CO2 “pollution” pricing is a strong indicator of a lack of belief in man-made global warming. One need not cherry pick at this proxy to confirm that the climate change threat is proving to be a motivational bust.
But all is not lost. We are moving forward with global electrification of transport. Big oil companies are seriously at work on alternative fuels. The urgency to end foreign oil imports is clear. And there is a healthy awareness of the need to balance development against the resources that allow it.
If only warmists hadn’t been so misanthropic in their zeal – and a lot less catastrophic in their performance – AGW may have done more good.

denny
October 1, 2009 9:29 pm

Mike Bryant (10:24:25) :
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
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
You’re not missing anything Mike…unlike some others who “responded” to
you…I understood exactly what you were asking. That’s probably because I’m
a retired long haul trucker, and not an Academic. The temp record should discredit
the dendro BUT….they do a lot of hand waving and mumbling of magic scientific
stuff that Plumbers, Truckers, and other common mortals aren’t capable of understanding….and that’s supposed to make it OK.
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Leif you hit the nail on the head as Mike had alluded to before.
Leif Svalgaard (12:09:52) :
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.
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
The problem with Leif’s suggestion as it concerns Steve Mc in particular and other Academics as well, is this….. He/they seemingly have ABSOLUTELY NO INTEREST in
whether or not tea leaves, chicken guts or tree rings are a proper metric for ascertaining ANYTHING. Their concerns are seemingly academic and procedural
in nature. It would seem that as long as the sampling and math is done correctly they don’t have a major problem with it.
Why in the hell would you be overly concerned with Ice Cores,when the glacier you’re
drilling on keeps spitting out VEGETATION indicating that the freeze line was
higher in the past. Or tree rings when, tree lines exist higher or further north than
the ones you’re sampling. It is completely beyond me as well….. but then I don’t
have a Diploma from a University. (Think the Wizard of OZ talking to the Scare Crow
here)
Dennis Dunton

bill
October 1, 2009 9:33 pm

Patrick Davis (20:45:26) :
http://www.cru.uea.ac.uk/cru/about/history/
Today, CRU is still dependent upon research grant income to maintain the size and breadth of our research and student communities. The European Commission of the European Union (EU) provides the largest fraction of our research income under the Environment and Climate Change Programme. …. Although EU funding is very important, we also endeavour to maintain the diverse pattern of funding reflected by the research described in this “history of CRU” and in the list of Acknowledgements below.
Since 1994, the situation has improved and now three of the senior staff are fully funded by ENV/UEA and two others have part of their salaries paid. The fact that CRU has and has had a number of long-standing research staff is testimony to the quality and relevance of our work. Such longevity in a research centre, dependent principally on soft money, in the UK university system is probably unprecedented. The number of CRU research staff as of the end of July 2007 is 15 (including those fully funded by ENV/UEA).
£226,981 is for the period:
01-Jul-03 30-Jun-08
£45,400/year.
The recipients are:
Prof K.R. Briffa
Prof P.D. Jones
Dr T. Osborn
Dr S. Tett
Thats about £11k each. assuming that no money is spent on research.
Keep real.

Jeremy
October 1, 2009 9:35 pm

£106,423: ECOCHANGE…
£125,000: Climate Change – Fellow 1 -modelling of the Earth’s climate…
£123,789: Process-based methods…
£121,880: To What Extent Was The Little Ice Age A Result Of…
£226,981: Quantitative applications of high resolution late Holocene…
£3,732: Statistical callibration of Eurasian tree ring records.
£1,000: ARC (Academic Research Collaboration) :Long tree ring….
Aha! It looks like the Briffalump has been at the Honey Jar!
Briffalumps love Honey!
“What have you decided, Steve “Pooh” Mcintyre?”
“I have decided to catch a Briffalump.”
Pooh nodded his head several times as he said this, and waited for Piglet to say “How?” or “Pooh, you couldn’t!” or something helpful of that sort, but Piglet said nothing. The fact was Piglet was wishing that he had thought about it first.
“I shall do it,” said Pooh, after waiting a little longer, “by means of a trap. And it must be a Cunning Trap, so you will have to help me, Piglet.”
“Pooh,” said Piglet, feeling quite happy again now, “I will.” And then he said, “How shall we do it?” and Pooh said, “That’s just it. How?” And then they sat down together to think it out.
Pooh’s first idea was that they should dig a Very Deep Pit, and then the Briffalump would come along and fall into the Pit, and—-“Why?” said Piglet.
“Why what?” said Pooh.
“Why would he fall in?”
Pooh rubbed his nose with his paw, and said that Briffalump might be walking along, humming a little song, and looking up at the trees, wondering about Global Climate (Briffalumps worry about these things you know), and so he wouldn’t see the Very Deep Pit until he was half-way down, when it would be too late.

AEGeneral
October 1, 2009 9:44 pm

Excellent rebuttal, Anthony. Keep the heat on ’em — no pun intended.
The mere presence of debate works in our favor, even if the media ignores it (which admittedly is frustrating). But at least this week’s revelations are on permanent record on the internet for all to see.
Debate: It’s not just for breakfast anymore.

October 1, 2009 9:46 pm

Tom Jones (20:15:48) :
1. Global temperatures have been rising in parallel with industrial development.
2. The rise in temperatures correlates well with CO2 in the atmosphere.
3. The rising temperatures are controllable by controlling CO2 in the atmosphere.
4. The rise in temperatures can be predicted by the climate models of the IPCC.
5. The rise over the rest of this century will be so large that it is incumbent on society to do whatever it takes to limit production of CO2.

Lets see if i understand this correctly as a “simple” person.
1. Yup, but a correlation is still not a cause. And this because in the past there have been periods when the average temperatures have been as warm or even warmer as it is now. There are several hundreds of publications backed by solid evidence that show a MWP and a LIA, the burden of proof is in your AGW-camp to show that this was caused by CO2. If you leave room for natural variation than i could suggest that a least part of the current warming is caused by natural factors, your task is to disprove this. Even the IPCC admits that at least a part of the warming is caused by natural factors.
2. No it does not. Especially on long periods of time in our past. But on a shorter timescale, the last 10 years do not correlate at all.
3. Unproven theory, because we only know how this works on a small scale in a laboratory, we still have no clue how this work on a global scale with a lot more natural and artificial factors (land-use, UHI and so on) thrown in, this is also the reason why modelling fails as a prediction tool.
4. No it can not, the margin of errors are to wide to make a sensible prediction. If you are to pick a number out of 100 than you should not choose 25 to 75 in the hope that you are correct somewhere in the next 9 decades.
Still its only a prediction, Lehman Brothers believed in AGW yet no one did predict that the bank would go belly-up within a year. Why should i trust those longterm predictions with so much unknown factors if shortterm economic predictions fail even if we know almost all factors that are in play?
5. Not very likely at all since all models did not predict the current decline in average temperatures. When does this thermageddon take off, now, in 10 years time, at the end of the century or perhaps never? And by how much? And what of that much is caused by artifical factors and what is cause by natural factors?
My question is, how much A is there in AGW (or ACC), it can’t be 100% nor can it be 0%, the current rise in temperature since 1850 is about 0.75 degrees celcius, if the factor A is 50% than 0.5 x 0.75 would result in 0.375 degrees. And my guess is that this factor A is even lower than 50%.
How much is factor A? The trees don’t tell us, thats for sure.

Pofarmer
October 1, 2009 10:00 pm

Some of the problems with bore hole measurements.
http://www.kilty.com/pdfs/t-d.pdf

Noelene
October 1, 2009 10:03 pm

Leif set me off googling tree rings indicate global warming,to see how much publicity there was about the subject.I came across a video on You Tube by a dendochronologist(he he I learnt a new word)

As a member of the unwashed masses(that phrase amuses me,it’s just so wrong )this lady is very convincing.The only part I wondered about was where she states that temperatures are warmer over the last couple of decades than they have been for a thousand years.Is there a thousand years of tree ring data?The video was uploaded in 2007,I don’t know what year it was made,but as a member of the public,with no interest in science,I have no reason to doubt this lady,why would I?I will see a lot of documentaries by educated people saying AGW is a problem,who am I(as a member of the unwashed masses)to challenge that?For me,my conclusion to all this
scientists are not as smart as they think they are,they have hoodwinked the public into believing they are smarter than they are.I am not saying all scientists,but it seems to me the majority have been corrupted.Time for a new broom,and accountability.

October 1, 2009 10:19 pm

Noelene (22:03:05) :
Is there a thousand years of tree ring data?
12,000 years or so.

James F. Evans
October 1, 2009 10:20 pm

“The Nobel Prize goes to the first person that can show why we are all wrong about _________.”
This statement is made many times by consensus scientists and their acolytes when others challenge them about a particular proposition or dogma.
It is an empty statement because they know that if the dogma is sacred enough, no amount of evidence will persuade the diehards that the dogma is wrong…that’s why it’s called dogma.
And they know who controls the voting for the Nobel Prize…those that maintain and enforce the dogma…

October 1, 2009 10:23 pm

Noelene (22:03:05) :
scientists are not as smart as they think they are
“You’ll probably find
that it suits your book
to be a bit cleverer
than you look.
Observe that the easiest
method by far
is to look a bit stupider
than you are.”
Piet Hein, scientist and poet

Gene Nemetz
October 1, 2009 10:37 pm

High speed internet connection : $35.00 a month.
Core duo computer, and monitor : $600.00
Time to read the post : 10 minutes.
The feeling of victory over Briffa and the Hockey Stick : Priceless.

Gene Nemetz
October 1, 2009 10:42 pm

Scott A. Mandia (18:12:27) : Here is an image from that article (striking isn’t it?):
http://www2.sunysuffolk.edu/mandias/global_warming/images/borehole_3.gif

It sure is!

anna v
October 1, 2009 10:43 pm

Scott A. Mandia (11:11:39) :
What bothers me the most about this story and appears to be a running theme here at WUWT is that somehow there is this massive conspiracy among scientists to delude the public for no other reason than we do not wish to look wrong. We certainly are not getting rich by taking the pro-AGW position. It is just silly.
It is not a matter of conspiracy in the political sense. It is in the sense of group think delusion, and yes, it happens to scientists. I have seen it happening in my field, particle physics, and, because people are really scientists and because there is not general publicity or world policy hanging on the scientific sidetracking, the system self corrects. It happens, i have experienced it,where a few scientists are gathered, and it happens where thousands are deluded by video and movies as is the recent case with this AGW morphed to CH “scientific” fad. Unfortunately the great opportunity of disseminating information, good or bad, has attracted politicians and politics to the reasonable controversy of methods used in measuring temperatures, who do have a vested money and other interest ( taxes, “this is the day of complete control”, etc) .
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. If so, then why bother trying to understand the past?
The hockey stick shape comes only with the dendro misuse of data.
Nobody that I know thinks that there has been no warming since the little ice age. It is evident and clear that there has. When you plot it, as with boreholes, on dramatic diagrams as in your http://www2.sunysuffolk.edu/mandias/global_warming/images/borehole_3.gif link, you are not doing a favor in your cause. As with changing from “global warming” to “climate change” it is a sleight of hand. In your link there is a rise of 1 C the last century?
So? We are coming out of the little ice age, on a downward slope from the maximum of the holocene with oscillation of the order of 1C http://en.wikipedia.org/wiki/File:Vostok-ice-core-petit.png
What is dramatically different in your borehole plot?
I am sorry but I think you are using sleight of hand/plot to defend the indifensible.

Gene Nemetz
October 1, 2009 11:02 pm

Caleb (18:59:33) : I’ve worked outside since I was a small boy in the 1950’s, and have cut down hundreds of trees. I always check out the rings, for every tree has its own story….Dr. Briffa should spend less time gazing at computer screens, and actually get out and associate with trees more. At the very least, it might be good for his health.
Caleb,
My grandpa was a lumberjack for most of his life. He was outside all day. He understood nature like you. In hunting season he was always the first to get his deer. He knew all about fertilizers for gardens. He knew the best day to plant crops—and boy, was he certain to plant them on those days! He could eye crops and know when they were ripe for picking. He seemed to know something about everything in nature. And he made it all seem so simple.
He never went to college.
Mr. Briffa would do well to sit and listen to people like you and my late grandpa.

Gene Nemetz
October 1, 2009 11:05 pm

James F. Evans (19:14:33) :
Liar, liar, pants on fire.
No, no more pants on fire. They burned up long ago. The Hockey Stick crowd is walking around in underwear.

October 1, 2009 11:23 pm

Nobody has said it, but bristlecone pines follow a C3 photosynthetic pathway. This is very important because the results of this characteristic on assessing the paleotemperatures could flaw any comparison with modern instrumental records. C3 plants do not respond to the intensity of solar irradiance in the same way that C4 plants do it. C3 plants prosper better in cold regions with a low incidence of solar radiation. Generally, C3 plants grow better in regions where the solar luminosity is about 50% of the total incident solar radiation. At higher proportions of luminosity, the photosynthetic process begins to decay and acquires the low original indexes at 100% of solar luminosity. The latter means that the growth of the treerings is delayed at high luminosities.
If some researchers intend to derive temperatures from this proxy, their results would be invariably flawed because the maximum temperature inferred from the maximum treerings growth will not be above 23 °C, always. If an increase of temperature occurs above 23 °C, the treerings growth would give the appearance of low temperatures. On the other hand, if the luminosity is higher than the 50% of the total luminosity, the treerings would widen less, giving a flawed result of high temperatures, when actually it was the excess of luminosity which caused the effect on the growth of the treerings. Assessing the other side of the coin, if the luminosity is higher than 50%, the treerings would not widen; however, when the luminosity gets back to values of 50% or less, the treerings would grow as if the temperature was higher, when in reality it is lower. The calibration is useless in these cases because we would never know when the slow growth was due to higher or to lower luminosity indexes.
Notice why I said the treerings are not good proxies for temperature, but for incident solar irradiance; nevertheless, there would be grim problems also if we take treerings seriously even for getting information about the incident solar irradiance.
That treerings are reliable sources of paleotemperatures is not true.

Tom P
October 2, 2009 12:14 am

Cross posted from Climate Audit:
October 1st, 2009 at 11:24 am
Steve McIntyre:
“The salient comparison here is between the CRU Archive and Schweingruber Variation.”
Tom P:
“specifically that portion used in your sensitivity analysis which was for live cores.”
Steve McIntyre:
“Are you seriously suggesting that CRU archive is more homogeneous in age distribution than the Schweingruber Variation?”
Tom P:
“It’s the duration of the tree cores that’s important to extract a long term signal. The CRU archive during the overlapping period with the Schweingruber series has much older trees in it, as you have already pointed out.
“Your sensitivity analysis replaces longer- with much shorter-lived tree cores and hence obscures the longer-term signal.”
Steve McIntyre has up to now been prompt in his response to my criticisms.

BobP
October 2, 2009 12:30 am

Let us have a look at the peers who do or did the reviews.
Who were the peers of e.g. Briffa 2000? Did they have any conflicting interests? How could they review e.g. Briffa 2000 without the data? Why did they not ask for the data? What did they review? Are there any written remarks, papers which document their reviews? I am sure that among the peers group there are some with rather sloppy working habits (as of course everywhere). Is there a check list of items peers have to look at? Is there a code of ethics which forbids to review papers of “friends”?
What about a map of the relations between all the peers and authors, which could serve as a demonstration of the non-existance or existance of a self-reference system? The term “Peer Reviewed” is in danger of becoming a cuss-word, as it is used so often to hide and not to clarify.
Why not a list of journals of premiere quality, journals which care about data (like The Royal Society) and journals with lower claims for quality, those which do not care about that. What are the journals’ criteria for selecting peers?
Bankers are greedy for money, scientists are greedy for reputation. Scientists who are hiding their data (+ their peers and journals) should be under attack from this point of view.
We need clarity and transparency in science.

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