For those that don’t read a lot of the WUWT comments closely, there has been a scholarly argument going on between Tom P of the UK and several WUWT commentators over the methodology Steve McIntyre used to illustrate the “breathtaking difference” between the plot of the hand picked set of 12 Yamal trees and the larger Schweingruber tree ring data set also from Yamal. Tom P. reworked Steve’s R-code script (which he posted on WUWT) to include both the 12 excluded and the Schweingruber and thought he found “insensitivity to additional data”, saying “There is no broken hockeystick”.
Jeff Id audited the auditor of an auditor and found that Steve’s work still holds up “robustly”. – Anthony
Just a short post tonight I hope. Tom P, an apparent believer in the hockey stick methods posted an entertaining reply to Steve McIntyre’s recent discoveries on Yamal. He used R code to demonstrate a flaw in SteveM’s method. His post was on WUWT, brought to my attention by Charles the moderator and is copied here where he declares victory over Steve.
Steve McIntryre’s [sic] reconstructions above are based on adding an established dataset, the Schweingruber Yamal sample instead of the “12 trees used in the CRU archive”. Steve has given no justification for removing these 12 trees. In fact they probably predate Briffa’s CRU analysis, being in the original Russian dataset established by Hantemirov and Shiyatov in 2002.
One of Steve’s major complaint about the CRU dataset was that it used few recent trees, hence the need to add the Schweingruber series. It was therefore rather strange that towards the end of the reconstruction the 12 living trees were excluded only to be replaced by 9 trees with earlier end dates.
I asked Steve what the chronology would look like if these twelve trees were merged back in, but no plot was forthcoming. So I downloaded R, his favoured statistical package, and tweaked Steve’s published code to include the twelve trees back in myself. Below is the chronology I posted on ClimateAudit a few hours ago.
TomP' s plot. Click to enlarge Source: http://img80.yfrog.com/img80/1808/schweingruberandcrud.png
The red line is the RCS chronology calculated from the CRU archive; black is the chronology calculated using the Schweingruber Yamal sample and the complete CRU archive. Both plots are smoothed with 21-year gaussian, as before. The y-axis is in dimensionless chronology units centered on 1.
It looks like the Yamal reconstruction published by Briffa is rather insensitive to the inclusion of the additional data. There is no broken hockeystick.
Jeff Id’s version of TomP’s graph – Click to expand
I spent some time tonight looking at his results. Time planned for analyzing Antarctic sea ice. I found that essentially the only difference in the operating functions of the code is the following line.
.
Steve M —- tree=rbind(yamal[!temp,],russ035)
Tom P —– tree=rbind(yamal,russ035)
.
The !temp in Steve’s line removes 12 series of Yamal for the average while Tom’s version includes it. I’m all for inclusion of all data, but I am a firm believer that Briffa’s data is probably a cherry picked set of trees to match temp or something. Therefore by inclusion of the sorted Briffa Yamal version, we have an automatic exclusion of data which would otherwise balance the huge trend. However, this is not the problem with Tom’s result. The problem lies in this plot, also created by Tom P’s code.
Tom P’s Yamal Reconstruction – Count per Year. Click to Expand
Here is the zoomed in version:
Above we can see that everything in TomP’s curve after 1990 is actually 100% Briffa Yamal data.
So the question becomes – What does the series look like if the Yamal data doesn’t create the ridiculous spike at the end the curve?
I truncated the black line at 1990 below.
The black line is truncated at the end of the Schweingruber data and it looks pretty similar to the graph presented in the green line by Steve McIntyre again below.
Don’t be too hard on Tom P, he honestly did a great job and took the time to work with the R script which is more than most are willing to. Steve is a very careful worker though and it’s damn near impossible to catch him making mistakes. Trust a serious skeptic, it’s not easy to find mistakes in his work and some of us check him just as I spent over an hour checking Tom’s work. In my opinion Tom deserves congratulations for his efforts and checking, this way we all learn.
I’ve now been all the way through SteveM’s scripts from beginning to end and can’t find any problems with the script, maybe others can!
There are 252 distinct series in the CRU archive. There are 12 IDs consisting of a 3-letter prefix, a 2-digit tree # and 1-digit core#. All 12 end in 1988 or later and presumably come from the living tree samples. The nomenclature of these core IDs url (POR01…POR11; YAD04…YAD12; JAH14…JAH16 – excluding the last digit of the ID here as it is a core #) suggests to me that there were at least 11 POR cores, 12 YAD cores and 16 JAH cores.
It is “possible” that they skipped ID numbers, but this is a farfetched theory even for Tom. As surmised here, the missing ID numbers are “evidence” of at least 39 cores and that the present archive is not only too small, but incomplete.
I am online too much, but I am not online 24/7. I’ve been out playing squash. Surely I’m allowed to be offline occasionally without a poster commenting adversely on this.
While I was out, CA crashed as well. Thus, it was “quiet.
Contrary to Tom’s speculations and misrepresentation of my statements, it is my opinion that there is considerable evidence that the 12 cores are not a complete population i.e. that they have been picked form a larger population. Rather than quote form actual text, Tom puts the following words in my mouth that I did not say:
Steve McIntyre said they may well have been just the most recent part of Hantemirov and Shiyatov’s dataset and no selection would have been made.
This is not my view.
The balance of Tom’s argument is:
No, they are the twelve most recent cores. There’s been no evidence provided to suggest they are in any way suspect. ..There is no obvious reason to exclude them.
I disagree. I do not believe that they constitute a complete population of recent cores. As a result, I believe that the archive is suspect. There is every reason to exclude them in order to carry out a sensitivity as I did. The sensitivity study showed very different results. I do not suggest that the sensitivity run be used as an alternative temperature history. Right now, there are far too many questions attached to this data set to propose any solution to the sampling conundrum. It’s only been a couple of days since the lamentable size of the CRU sample became known and it will take a little more time yet to assess things.
Reasons why I “suspect” that a selection was made from a larger population include the following. A field dendro could take 12 cores in an hour. We took a lot more than that at Mt Allegre and a field dendro could be far more efficient. Thus, it seems very unlikely that the entire population of cores from the Yamal program is only 12 cores and on this basis, it is my surmise that a selection was taken from the cores. Standard dendro procedures use all crossdated cores and definitely use more than 10 cores if they are available.
This doesn’t “prove” that a selection was made, but it is reasonable to “suspect” that a selection was made and to ask CRU and their Russian associates to provide a clear statement of their protocols. There’s no urgency to do anything prior to receiving a statement of their sampling protocols. For this purpose, it doesn’t matter a whit whether the selection was made by the Russians or at CRU or a combination. In my first post on this matter – which Tom appears not to have read, I canvass the limited evidence for and against. There is certainly evidence supporting the idea that the 12 cores were among 17 selected by the Russians, but in other parts of the data set, the CRU population is larger than that used in the Hantemirov and Shiyatov chronology. The construction of the CRU data set is not described in any literature; the description in Hantemirov and Shiyatov has something to do with it, but doesn’t yield the CRU data data set. Some sort of reconciliation is required.
In addition, the age distribution of the CRU 12 is very different than the age distribution from the nearby Schweingruber population. In my opinion, the uniformly high age of the CRU12 relative to the Schweingruber population is suggestive of selection – in this respect, perhaps and even probably by the Russians. Again this isnt proof. Maybe they were just lucky 12 straight times and, unlike Schweingruber, they got very long-lived trees with every core. Without documentaiton, no one knows. In any event, this doesn’t help the Briffa situation. If these things are temperature proxies, the results from two different nearby populations should not be so different and protocols need to be established for ensuring that the age distribution of the modern sample is relatively homogeneous with the subfossil samples (and they aren’t.)
The prevailing dendro view is that an RCS chronology requires a much larger population than a “conventional” standardization. Thus, even if the data set had been winnowed down to 10 cores in 1990 and 5 cores at the end, this is an absurdly low population for modern cores, which are relatively easily obtained. Use of such small replication is inconsistent with Briffa’s own methodological statements.
Tom also misses a hugely important context. There is a nearby site (Polar Urals) with an ample supply of modern core. Indeed, at one time, Briffa used Polar Urals to represent this region. My original question was whether there was a valid reason for substituting Yamal for Polar Urals. The microscopic size of the modern record suggests that there was not a valid reason. However, this tiny sample size was not known to third parties until recently due to Briffa’s withholding of data, not just from me, but also to D’Arrigo, Wilson et al.
Until details of the Yamal selection process are known, my sense right now is that one cannot blindly assume – as Tom does – that what we see is a population. Maybe this will prove to be the case, but personally I rather doubt it. A better approach is to use the Polar Urals data set as a building block.
As to Tom’s argument that none of this “matters”, the Yamal data set has a bristlecone-like function in a number of reconstructions. While the differences between the versions may not seem like a lot to Tom, as someone with considerable experience with this data, it is my opinion that the revisions will have a material impact on the medieval-modern difference in the multiproxy studies that do not depend on strip bark bristlecones.
Tom P can’t do it. Lorax brings nothing but querelousnous. Scott Mandia is stuck in group think. Keith Briffa mumbles under his breath. The ‘Bulldog’ Tamino is hors de combat, and his commenters are their usual disgusting selves. Real Climate is a horror show. God’s in his Heaven; all’s right with the world.
==============================
Tom P
October 2, 2009 12:39 am
Jeff Id (12:49:49) :
Why Steve McIntrye’s analysis is injecting noise into any long term trends is conceptually simple:
As I posted on CA:
Trying to discern a centennial or multicentennial trend using noisy samples less than one hundred years long is next to impossible.
Here’s a simple example. Imagine a noisy, gently upwards trending signal one thousand years long. Chop that signal into one-hundred year segments and set the average of each of these segments to zero. It is very difficult to then recover the initial trend by then stitching together the segments.
To see Steve McIntyre is injecting noise you only have to look at his own plot here: http://www.climateaudit.org/wp-content/uploads/2009/10/age_yamal1.gif
The age of the samples Steve is using is the green line in the plot.
Although Steve promised a graphical rebuttal to my points yesterday morning, this has yet to appear.
Layman Lurker (13:02:30) :
I’ve popped no champagne corks. I actually find this episode rather sad. Steve McIntyre’s failed sensitivity analysis has been used by a much wider audience to undermine the Yamal hockey stick. This blog may move on to other matters, but damage has been done.
Dodgy Geezer
October 2, 2009 4:55 am
“..Tom P, don’t you wonder where the principal ‘peers’ involved in this train wreck are? Now, I know one of them is physically sick; are the others sick at heart? Why are you the lone voice disputing an apparently killer argument from Steve?..”
kim
I don’t think that we can repeat too often that real science is about disputation. It is CRITICALLY IMPORTANT that we have lone voices disputing apparently killer arguments. A moments though will remind you that this describes Steve as well as Tom P.
There is no point in people who agree with each other starting a mutual admiration society. It may give them a warm feeling, but it cannot arrive at the truth. Tom P is testing Steve’s hypothesis as hard as he can – if it survives it will come out much stronger. Tom should be praised for this – if he cannot disprove Steve he really is helping to make the case against the Briffa 12.
And he may succeed. If so, I assume that all Climate Audit readers would want to know the truth, rather than sit in a fabriacted world of their own invention?
So what Tom P is doing gets my vote. I wish more AGW supporters would address the real issues in the way that he is doing….
Jack Simmons
October 2, 2009 5:07 am
In the language of its indigenous inhabitants, the Nenets, “Yamal” means “End of the World”.
kim
October 2, 2009 7:05 am
Well, sure DG, I can’t argue with what you say. My point to Tom P was to get him to wonder why there seemed to be no other support for his dissent. The answer was short in coming; there are others now joining in the attack on McIntyre’s point, but as is painfully obvious, none of them have much relevant to say.
My lesson to Tom P stands. McIntyre has made trenchant criticism, so far unanswered by anyone.
================
Dodgy Geezer
October 2, 2009 7:39 am
“…My point to Tom P was to get him to wonder why there seemed to be no other support for his dissent…”
kim
For the record, I believe that Tom P is wrong. But your position seems to me to be exactly the same as those who say that ‘the consensus’ of science is pro-AGW, so protestors should withdraw. This is not only wrong, but dangerous to the sceptic position and science generally.
So long as the two sides stay in mutually opposing camps, each hurling insults at the other, there is no chance of a proper debate. Frightening away opponents who are willing to engage in debate will retain that division, and maintain a situation where Briffa and Tamino can just ‘ignore’ McIntyre. We believe we are right, and we NEED a debate so that we can win it. At the moment we have each side saying that the other is so misguided/evil/criminal that there is no need for a debate.
This is like a boxing match where the opponents talk big before the event, then circle each other in the ring but never come to blows. Tom P has just stepped up. Don’t duck, weave and then back off…
kim
October 2, 2009 8:21 am
I said I don’t disagree with your point, DG.
But now, look, Steve has moved the whole Lorax diversion in the Briffa thread at CA to unthreaded. There is a dynamic, at which McIntyre is a master, at editing a thread to keep it on a specific track, and McIntyre’s masterliness leaves most threads at CA scientifically intact and highly useful to the serious participants(I speak as being generally a member of the McKitrick described ‘Peanut Gallery’).
The key points in this whole brouhaha are these: 1. Ten is too few to analyze via RCS. 2. Briffa must explain his selection criteria of those ten.
I attacked Tom P initially because he had a wrong and unscientific point. He still has. There’s a difference between honest scientific rhetoric and that which is not. I will defend to the death his right to say what he likes, but also will I my right to respond as I see fit.
Er, all subject to the Will of the Moderators, of course. Thank you, My Overlords.
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Layman Lurker
October 2, 2009 8:26 am
re: Tom P (00:39:34)
Tom P. you have not demonstrated anything let alone shown that Steve’s case collapses. It is another strawman. Briffa’s reconstruction is flat pre-insturmental with an MWP uptick. Are you suggesting that the centennial scale signal in Schweingruber is so different from CRU that it conceals a dramatic MWP? What kind of positive 100 year linear slope would it take to do that? Either there is not enough difference to affect the MWP comparison or the 100 year trends of the two data sets are seriously different. Either way their is a serious problem.
Tom P
October 2, 2009 8:29 am
kim (07:05:50) :
“McIntyre has made trenchant criticism, so far unanswered by anyone.”
Wrong way round. I am waiting for a response from McIntyre that all his sensitivity test amounts to is contaminating the data with noise.
Dodgy Geezer (07:39:11) :
I have defined on Climate Audit a non-biased sensitivity analysis of the CRU data for Steve McIntyre:
“…a sensitivity analysis based on recalculation of the Briffa Yamal plot only using trees with ages above a certain value. It would be very useful to see how sensitive the shape is tree age – we’d see how the snake bends as its bones grow older…”
The hockey stick might hold up as the shorter cores are removed from the entire record. On the other hand we might see a medieval warm period emerging.
I have no idea what will be the result, but I am impatient to see it. This is potentially publishable work.
McIntyre’s original sensitivity test, which was effectively throwing short cores in to the end of the record to suppress the blade of the hockey stick, had no validity, even if it created a stir. This new sensitivity test will really tell us if the original Yamal hockey stick holds up.
Dodgy Geezer
October 2, 2009 9:00 am
“(I speak as being generally a member of the McKitrick described ‘Peanut Gallery’)…”
kim
I wish I could apply for the peanut gallery. But that’s far too advanced for me….
“..There’s a difference between honest scientific rhetoric and that which is not. I will defend to the death his right to say what he likes, but also will I my right to respond as I see fit…”
kim
No problem whatsoever with your right to say anything you like. I am in there fighting alongside you on that. What I am questioning is the wisdom of responding as you see it – ‘like for like’. I believe we should be dragging the argument to a higher level, and, it appears, Tom P agrees.
I am not sure if Tom’s proposal:
“…I have defined on Climate Audit a non-biased sensitivity analysis of the CRU data for Steve McIntyre:…This new sensitivity test will really tell us if the original Yamal hockey stick holds up…” TomP
is a valid one or not – he is moving in regions of dendro statistics which are out of my depth – but I am sure Steve will consider his point and either rebut it or address it. I don’t think that “no support for his dissent” is a valid reason to reject it – if we say that we are no better than Real Climate…
Tom P
October 2, 2009 9:14 am
Layman Lurker (08:26:37):
“Are you suggesting that the centennial scale signal in Schweingruber is so different from CRU that it conceals a dramatic MWP?”
The Schweingruber data only goes back to 1782 – your point I’m afraid only shows that you’ve not really been keeping up.
TomP
Good stuff. It is important that the auditors are audited and held to account if they are wrong. It is a shame this particular game was not played out a decade ago and the archive material made available.
Keep up the good work even if I’m not on your side.
tonyb
Layman Lurker
October 2, 2009 12:55 pm
Let me correct an error in my last post. My references to the “MWP” should have read “CWP”. My bad.
Tom Here’s a simple example. Imagine a noisy, gently upwards trending signal one thousand years long. Chop that signal into one-hundred year segments and set the average of each of these segments to zero. It is very difficult to then recover the initial trend by then stitching together the segments.
This is not what happens in the Yamal standardization. All core samples are divided by the same value for each year. There is no centering (setting average to 0) of individual series for the mean.
Tom P
October 2, 2009 4:09 pm
Jeff Id (13:09:11) :
You’re right, my example was oversimplified. In fact it is the trend that is squashed in each individual segment by an RCS chronology, so the continuous trend becomes a staircase.
Using shorter rather than longer cores will still distort the chronology and suppress trends. The best way to see how this might affect the data is to do a sensitivity test just as I suggest.
I know you are skilled at R. Would you be willing to give it a go?
kim
October 2, 2009 8:04 pm
DG 09:00:40
Touche. I’ve been sensitized by too much close combat. Yes, I’m a thug. I’ve actually dialed back lately, because I recognize there are more effective voices.
Tom P. 08:29:28
I regret accusing you of not being scientific. But here’s my objection. The two key points in this brouhaha are 1) Briffa used too small a sample for the RCS methodology, and 2) He must, and has not yet, explain how the choice of this sample was made. You have a relatively irrelevant objection about Steve’s choice of sample. You can make that objection because you know how Steve chose that sample. Can we say the same about Briffa’s choice?
So that’s why the inappropriate snark about science. Your not getting it seemed unscientific, though your objection is plenty quantitative.
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kim
October 2, 2009 8:16 pm
Heh, DG, have you just audited me? Perhaps I can learn from you. I’ve already said that I hope this ends in ridicule and not anger, but of course, respectful mutual understanding is far better. Bender has published a clue, over on CA from a Briffa 2006 paper, suggesting that really what happened is that this coterie of climatologists was just naive about statistics. They really didn’t understand that it was inappropriate to compare their samples with the temperature record.
I’ve also remarked that it is very difficult to really pinpoint those with evil intentions among the climate alarmists; the scientists, the journalists, and the politicians. This really has been a ‘Popular Delusion, and the Madness of Crowds’.
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Tom P
October 3, 2009 12:07 am
kim (20:04:11) :
“1) Briffa used too small a sample for the RCS methodology”
I don’t believe so. Looking at figure 7 of this reference http://www.treeringsociety.org/TRBTRR/TRRvol60_2_77-90.pdf
which models the statistics for the reliability of RCS chronology, even a small number of trees (15 to 20 total) with sufficient overlap can discriminate a high enough amplitude signal.
This figure also shows that 12 records at any one time (the CRU 12) is not below a statistical threshold of validity. As good coherence can be obtained for as few as 15 trees of average age 550 years distributed over 2000 years, the threshold can be as few as 4 trees at any one time.
“2) He must, and has not yet, explain how the choice of this sample was made.”
From Briffa’s response:
“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).”
The Hantemirov and Shiyatov were processing the data in 2002 so that long-term trends were not apparent (the WUWT article “More Yamal tree ring temperature data: this data is flat as roadkill” rather misses this point), so there could have been no attempt to create a hockey stick by any selection they made.
There is no reason to think there has been any misconduct going on here. In fact Steve McIntyre has written: “I did not say or imply that Briffa had “purposely selected” individual cores into the chronology and clearly said otherwise.”
What there may have been, and what my proposed sensitivity test will show, is an inadvertent bias introduced by the number of shorter fossil records making up the earlier part of the record. I don’t think this is a selection bias, just that the fossil trees are more often found as shorter records. But this might affect the chronology.
Tom P,
I’m not sure if you saw it, but Roman M posted a chart showing the age of the chronologies used in Steve’ s graph. it shows that the 12 CRU are, at their longest, about 400 years old. It also shows that several of the cores from the other study are of about the same length. And both also have shorter time series included. Does this help or hurt your argument? http://statpad.files.wordpress.com/2009/10/yamaltrings1.jpg
I won’t be able to reply for the rest of the day. Have a long gig, (singin and playin bass and having a grand time at a car show), then when I get back from that, have a dinner theater engagement with the in-laws. Will check back late tonight.
Man, gotta tell ya, I’m learning more about the nature of these studies than I have in the ten years I’ve been following the AGW debate.
Mike
OK… I see you are still following that thread. I’ll check that one tonight too.
Tom P
October 3, 2009 8:44 am
I’m afraid I lost my patience and have kludged Steve McIntyre’s code to do my sensitivity analysis (code is posted on Climate Audit).
First, here is the chronology without YAD061: http://img515.imageshack.us/i/oyad06.pdf/
Whatever that tree was drinking, it looked like it shared the round.
Now for the sensitivity analysis for the CRU archive:
1) Removing the cores less than 72 years old – the drooping tail at the end of the distribution I posted on CA: http://img406.imageshack.us/i/cru72.pdf/
As I suspected, these cores don’t contribute much to the chronology.
2) Removing the cores less than 100 years old: http://img25.imageshack.us/i/cru100.pdf/
Not much difference.
3) Removing the cores less than 150 years old: http://img156.imageshack.us/i/cru150.pdf/
Still not much of a shift.
4) Removing the cores less than 200 years old: http://img59.imageshack.us/i/cru200.pdf/
This has removed YAD06 amongst other cores, but the profile remains the same. The noise is increasing but the shape is till clear. There are now 64 cores left, with an average age of 262 years, or an average of 8 cores at any one time.
5) Removing the cores less than 250 years old: http://img202.imageshack.us/i/cru250.pdf/
Now there are just 32 cores left with an average age of 303 years, or just four cores at any one time. The hockeystick has finally been broken, but only by removing so many cores that the noise has finally overcome the signal.
Briffa’s result appears robust to a very demanding test. I await Steve McIntyre’s response to this.
Tom P
October 3, 2009 9:34 am
Moderator: the first link in my post above is broken. Please add a slash.
kim
October 4, 2009 6:12 am
Tom P 00:07:30
Heh, your figure 7 supports my argument, not yours. It says if the signal is of high enough amplitude, a small number of trees may suffice. Tell me the signal supposedly being found, temperature response, is of ‘high enough amplitude’? Not.
Secondly, Briffa chose from among the sample that the Russians picked for an entirely different methodology, corridor standardization. Briffa must explain his choices.
Frankly, as I’ve previously said, what McIntyre does or does not demonstrate is almost irrelevant, as are your criticisms of it. The ball would be in Briffa’s court to justify his methodology even if Steve had never seen it. The ball is in Briffa’s court, despite your running laps in an entirely different stadium. You are not even wrong, my friend.
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Tom P
October 4, 2009 8:17 am
Kim,
The increase in the index in the Yamal series seen in the twentieth century is more than 100%, from an index of 1 to over 2.
Briffa uses the same series as the Russians and applied a different methodology, RCS, to identify the long-term climate signal. There’s no choice to be explained.
Read Briffa’s papers and explain your criticisms of his methodology. I agree, though, that MacIntyre’s invalid analysis is irrelevant.
kim
October 4, 2009 5:53 pm
YAD06 with an 8 sigma is warranted is a series this small. You’ve not answered my objection, that the temperature signal was too small to be found with significant confidence by such a small sample. These are two sides of the same coin; that the sample is too small for analysis by RCS. Nevermind that he was also naive enough at statistics to not know that he shouldn’t have compared the sample with temperature, whether he actually did this or not. Over on CA, Bender documents his naivete, and apparently that of other Briffa co-authors, in that elementary statistical principle.
=============================
For those that don’t read a lot of the WUWT comments closely, there has been a scholarly argument going on between Tom P of the UK and several WUWT commentators over the methodology Steve McIntyre used to illustrate the “breathtaking difference” between the plot of the hand picked set of 12 Yamal trees and the larger Schweingruber tree ring data set also from Yamal. Tom P. reworked Steve’s R-code script (which he posted on WUWT) to include both the 12 excluded and the Schweingruber and thought he found “insensitivity to additional data”, saying “There is no broken hockeystick”.
Tom P’s Yamal Reconstruction – Count per Year. Click to Expand
![rcs_merged_rev[1]](http://noconsensus.files.wordpress.com/2009/09/rcs_merged_rev11.gif "rcs_merged_rev[1]")
Tom P can’t do it. Lorax brings nothing but querelousnous. Scott Mandia is stuck in group think. Keith Briffa mumbles under his breath. The ‘Bulldog’ Tamino is hors de combat, and his commenters are their usual disgusting selves. Real Climate is a horror show. God’s in his Heaven; all’s right with the world.
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Jeff Id (12:49:49) :
Why Steve McIntrye’s analysis is injecting noise into any long term trends is conceptually simple:
As I posted on CA:
Trying to discern a centennial or multicentennial trend using noisy samples less than one hundred years long is next to impossible.
Here’s a simple example. Imagine a noisy, gently upwards trending signal one thousand years long. Chop that signal into one-hundred year segments and set the average of each of these segments to zero. It is very difficult to then recover the initial trend by then stitching together the segments.
To see Steve McIntyre is injecting noise you only have to look at his own plot here:
http://www.climateaudit.org/wp-content/uploads/2009/10/age_yamal1.gif
The age of the samples Steve is using is the green line in the plot.
Although Steve promised a graphical rebuttal to my points yesterday morning, this has yet to appear.
Layman Lurker (13:02:30) :
I’ve popped no champagne corks. I actually find this episode rather sad. Steve McIntyre’s failed sensitivity analysis has been used by a much wider audience to undermine the Yamal hockey stick. This blog may move on to other matters, but damage has been done.
“..Tom P, don’t you wonder where the principal ‘peers’ involved in this train wreck are? Now, I know one of them is physically sick; are the others sick at heart? Why are you the lone voice disputing an apparently killer argument from Steve?..”
kim
I don’t think that we can repeat too often that real science is about disputation. It is CRITICALLY IMPORTANT that we have lone voices disputing apparently killer arguments. A moments though will remind you that this describes Steve as well as Tom P.
There is no point in people who agree with each other starting a mutual admiration society. It may give them a warm feeling, but it cannot arrive at the truth. Tom P is testing Steve’s hypothesis as hard as he can – if it survives it will come out much stronger. Tom should be praised for this – if he cannot disprove Steve he really is helping to make the case against the Briffa 12.
And he may succeed. If so, I assume that all Climate Audit readers would want to know the truth, rather than sit in a fabriacted world of their own invention?
So what Tom P is doing gets my vote. I wish more AGW supporters would address the real issues in the way that he is doing….
In the language of its indigenous inhabitants, the Nenets, “Yamal” means “End of the World”.
Well, sure DG, I can’t argue with what you say. My point to Tom P was to get him to wonder why there seemed to be no other support for his dissent. The answer was short in coming; there are others now joining in the attack on McIntyre’s point, but as is painfully obvious, none of them have much relevant to say.
My lesson to Tom P stands. McIntyre has made trenchant criticism, so far unanswered by anyone.
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“…My point to Tom P was to get him to wonder why there seemed to be no other support for his dissent…”
kim
For the record, I believe that Tom P is wrong. But your position seems to me to be exactly the same as those who say that ‘the consensus’ of science is pro-AGW, so protestors should withdraw. This is not only wrong, but dangerous to the sceptic position and science generally.
So long as the two sides stay in mutually opposing camps, each hurling insults at the other, there is no chance of a proper debate. Frightening away opponents who are willing to engage in debate will retain that division, and maintain a situation where Briffa and Tamino can just ‘ignore’ McIntyre. We believe we are right, and we NEED a debate so that we can win it. At the moment we have each side saying that the other is so misguided/evil/criminal that there is no need for a debate.
This is like a boxing match where the opponents talk big before the event, then circle each other in the ring but never come to blows. Tom P has just stepped up. Don’t duck, weave and then back off…
I said I don’t disagree with your point, DG.
But now, look, Steve has moved the whole Lorax diversion in the Briffa thread at CA to unthreaded. There is a dynamic, at which McIntyre is a master, at editing a thread to keep it on a specific track, and McIntyre’s masterliness leaves most threads at CA scientifically intact and highly useful to the serious participants(I speak as being generally a member of the McKitrick described ‘Peanut Gallery’).
The key points in this whole brouhaha are these: 1. Ten is too few to analyze via RCS. 2. Briffa must explain his selection criteria of those ten.
I attacked Tom P initially because he had a wrong and unscientific point. He still has. There’s a difference between honest scientific rhetoric and that which is not. I will defend to the death his right to say what he likes, but also will I my right to respond as I see fit.
Er, all subject to the Will of the Moderators, of course. Thank you, My Overlords.
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re: Tom P (00:39:34)
Tom P. you have not demonstrated anything let alone shown that Steve’s case collapses. It is another strawman. Briffa’s reconstruction is flat pre-insturmental with an MWP uptick. Are you suggesting that the centennial scale signal in Schweingruber is so different from CRU that it conceals a dramatic MWP? What kind of positive 100 year linear slope would it take to do that? Either there is not enough difference to affect the MWP comparison or the 100 year trends of the two data sets are seriously different. Either way their is a serious problem.
kim (07:05:50) :
“McIntyre has made trenchant criticism, so far unanswered by anyone.”
Wrong way round. I am waiting for a response from McIntyre that all his sensitivity test amounts to is contaminating the data with noise.
Dodgy Geezer (07:39:11) :
I have defined on Climate Audit a non-biased sensitivity analysis of the CRU data for Steve McIntyre:
“…a sensitivity analysis based on recalculation of the Briffa Yamal plot only using trees with ages above a certain value. It would be very useful to see how sensitive the shape is tree age – we’d see how the snake bends as its bones grow older…”
The hockey stick might hold up as the shorter cores are removed from the entire record. On the other hand we might see a medieval warm period emerging.
I have no idea what will be the result, but I am impatient to see it. This is potentially publishable work.
McIntyre’s original sensitivity test, which was effectively throwing short cores in to the end of the record to suppress the blade of the hockey stick, had no validity, even if it created a stir. This new sensitivity test will really tell us if the original Yamal hockey stick holds up.
“(I speak as being generally a member of the McKitrick described ‘Peanut Gallery’)…”
kim
I wish I could apply for the peanut gallery. But that’s far too advanced for me….
“..There’s a difference between honest scientific rhetoric and that which is not. I will defend to the death his right to say what he likes, but also will I my right to respond as I see fit…”
kim
No problem whatsoever with your right to say anything you like. I am in there fighting alongside you on that. What I am questioning is the wisdom of responding as you see it – ‘like for like’. I believe we should be dragging the argument to a higher level, and, it appears, Tom P agrees.
I am not sure if Tom’s proposal:
“…I have defined on Climate Audit a non-biased sensitivity analysis of the CRU data for Steve McIntyre:…This new sensitivity test will really tell us if the original Yamal hockey stick holds up…” TomP
is a valid one or not – he is moving in regions of dendro statistics which are out of my depth – but I am sure Steve will consider his point and either rebut it or address it. I don’t think that “no support for his dissent” is a valid reason to reject it – if we say that we are no better than Real Climate…
Layman Lurker (08:26:37):
“Are you suggesting that the centennial scale signal in Schweingruber is so different from CRU that it conceals a dramatic MWP?”
The Schweingruber data only goes back to 1782 – your point I’m afraid only shows that you’ve not really been keeping up.
TomP
Good stuff. It is important that the auditors are audited and held to account if they are wrong. It is a shame this particular game was not played out a decade ago and the archive material made available.
Keep up the good work even if I’m not on your side.
tonyb
Let me correct an error in my last post. My references to the “MWP” should have read “CWP”. My bad.
Tom
Here’s a simple example. Imagine a noisy, gently upwards trending signal one thousand years long. Chop that signal into one-hundred year segments and set the average of each of these segments to zero. It is very difficult to then recover the initial trend by then stitching together the segments.
This is not what happens in the Yamal standardization. All core samples are divided by the same value for each year. There is no centering (setting average to 0) of individual series for the mean.
Jeff Id (13:09:11) :
You’re right, my example was oversimplified. In fact it is the trend that is squashed in each individual segment by an RCS chronology, so the continuous trend becomes a staircase.
Using shorter rather than longer cores will still distort the chronology and suppress trends. The best way to see how this might affect the data is to do a sensitivity test just as I suggest.
I know you are skilled at R. Would you be willing to give it a go?
DG 09:00:40
Touche. I’ve been sensitized by too much close combat. Yes, I’m a thug. I’ve actually dialed back lately, because I recognize there are more effective voices.
Tom P. 08:29:28
I regret accusing you of not being scientific. But here’s my objection. The two key points in this brouhaha are 1) Briffa used too small a sample for the RCS methodology, and 2) He must, and has not yet, explain how the choice of this sample was made. You have a relatively irrelevant objection about Steve’s choice of sample. You can make that objection because you know how Steve chose that sample. Can we say the same about Briffa’s choice?
So that’s why the inappropriate snark about science. Your not getting it seemed unscientific, though your objection is plenty quantitative.
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Heh, DG, have you just audited me? Perhaps I can learn from you. I’ve already said that I hope this ends in ridicule and not anger, but of course, respectful mutual understanding is far better. Bender has published a clue, over on CA from a Briffa 2006 paper, suggesting that really what happened is that this coterie of climatologists was just naive about statistics. They really didn’t understand that it was inappropriate to compare their samples with the temperature record.
I’ve also remarked that it is very difficult to really pinpoint those with evil intentions among the climate alarmists; the scientists, the journalists, and the politicians. This really has been a ‘Popular Delusion, and the Madness of Crowds’.
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kim (20:04:11) :
“1) Briffa used too small a sample for the RCS methodology”
I don’t believe so. Looking at figure 7 of this reference
http://www.treeringsociety.org/TRBTRR/TRRvol60_2_77-90.pdf
which models the statistics for the reliability of RCS chronology, even a small number of trees (15 to 20 total) with sufficient overlap can discriminate a high enough amplitude signal.
This figure also shows that 12 records at any one time (the CRU 12) is not below a statistical threshold of validity. As good coherence can be obtained for as few as 15 trees of average age 550 years distributed over 2000 years, the threshold can be as few as 4 trees at any one time.
“2) He must, and has not yet, explain how the choice of this sample was made.”
From Briffa’s response:
“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).”
The Hantemirov and Shiyatov were processing the data in 2002 so that long-term trends were not apparent (the WUWT article “More Yamal tree ring temperature data: this data is flat as roadkill” rather misses this point), so there could have been no attempt to create a hockey stick by any selection they made.
There is no reason to think there has been any misconduct going on here. In fact Steve McIntyre has written: “I did not say or imply that Briffa had “purposely selected” individual cores into the chronology and clearly said otherwise.”
What there may have been, and what my proposed sensitivity test will show, is an inadvertent bias introduced by the number of shorter fossil records making up the earlier part of the record. I don’t think this is a selection bias, just that the fossil trees are more often found as shorter records. But this might affect the chronology.
Tom P,
I’m not sure if you saw it, but Roman M posted a chart showing the age of the chronologies used in Steve’ s graph. it shows that the 12 CRU are, at their longest, about 400 years old. It also shows that several of the cores from the other study are of about the same length. And both also have shorter time series included. Does this help or hurt your argument?
http://statpad.files.wordpress.com/2009/10/yamaltrings1.jpg
I won’t be able to reply for the rest of the day. Have a long gig, (singin and playin bass and having a grand time at a car show), then when I get back from that, have a dinner theater engagement with the in-laws. Will check back late tonight.
Man, gotta tell ya, I’m learning more about the nature of these studies than I have in the ten years I’ve been following the AGW debate.
Mike
OK… I see you are still following that thread. I’ll check that one tonight too.
I’m afraid I lost my patience and have kludged Steve McIntyre’s code to do my sensitivity analysis (code is posted on Climate Audit).
First, here is the chronology without YAD061:
http://img515.imageshack.us/i/oyad06.pdf/
Whatever that tree was drinking, it looked like it shared the round.
Now for the sensitivity analysis for the CRU archive:
1) Removing the cores less than 72 years old – the drooping tail at the end of the distribution I posted on CA:
http://img406.imageshack.us/i/cru72.pdf/
As I suspected, these cores don’t contribute much to the chronology.
2) Removing the cores less than 100 years old:
http://img25.imageshack.us/i/cru100.pdf/
Not much difference.
3) Removing the cores less than 150 years old:
http://img156.imageshack.us/i/cru150.pdf/
Still not much of a shift.
4) Removing the cores less than 200 years old:
http://img59.imageshack.us/i/cru200.pdf/
This has removed YAD06 amongst other cores, but the profile remains the same. The noise is increasing but the shape is till clear. There are now 64 cores left, with an average age of 262 years, or an average of 8 cores at any one time.
5) Removing the cores less than 250 years old:
http://img202.imageshack.us/i/cru250.pdf/
Now there are just 32 cores left with an average age of 303 years, or just four cores at any one time. The hockeystick has finally been broken, but only by removing so many cores that the noise has finally overcome the signal.
Briffa’s result appears robust to a very demanding test. I await Steve McIntyre’s response to this.
Moderator: the first link in my post above is broken. Please add a slash.
Tom P 00:07:30
Heh, your figure 7 supports my argument, not yours. It says if the signal is of high enough amplitude, a small number of trees may suffice. Tell me the signal supposedly being found, temperature response, is of ‘high enough amplitude’? Not.
Secondly, Briffa chose from among the sample that the Russians picked for an entirely different methodology, corridor standardization. Briffa must explain his choices.
Frankly, as I’ve previously said, what McIntyre does or does not demonstrate is almost irrelevant, as are your criticisms of it. The ball would be in Briffa’s court to justify his methodology even if Steve had never seen it. The ball is in Briffa’s court, despite your running laps in an entirely different stadium. You are not even wrong, my friend.
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Kim,
The increase in the index in the Yamal series seen in the twentieth century is more than 100%, from an index of 1 to over 2.
Briffa uses the same series as the Russians and applied a different methodology, RCS, to identify the long-term climate signal. There’s no choice to be explained.
Read Briffa’s papers and explain your criticisms of his methodology. I agree, though, that MacIntyre’s invalid analysis is irrelevant.
YAD06 with an 8 sigma is warranted is a series this small. You’ve not answered my objection, that the temperature signal was too small to be found with significant confidence by such a small sample. These are two sides of the same coin; that the sample is too small for analysis by RCS. Nevermind that he was also naive enough at statistics to not know that he shouldn’t have compared the sample with temperature, whether he actually did this or not. Over on CA, Bender documents his naivete, and apparently that of other Briffa co-authors, in that elementary statistical principle.
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