Open Thread

I have closed several comment threads which were the recipients of the bulk of recent "spam" comments - it's pretty annoying weeding through all that stuff, so hopefully this will simplify my life a little.

Several people have asked me for my further views on the Hockey Stick, particularly given the recent extensive discussion at RealClimate. I've definitely felt enlightened by some of the discussion that's taken place in threads here. I have downloaded and started to read through Mann's 2008 paper and look at some of the associated data, but my personal comfort level with the science is still too low to make any really substantive comment. From what's been said by both sides it does seem to me that Mann has been careless in a rather long series of particular examples, but again my comfort level with the state of data handling in this field is still much too low to say whether he was abnormally careless, or simply facing the usual levels of befuddlement we all do when looking at complex collections of information. Steve McIntyre's recent Make a Stick article might be useful too - but once again I find his actual conclusions very hard to pull out from the vagueness and unreferenced allusions.

Anyway, given that some of the closed threads had recent non-spam comments, feel free to continue raising issues under this thread, which I will moderate very lightly if at all (as per the title, pretty much everything's on topic). Thanks.

[Update - 40 hours later and still 0 comments on the approval queue - sorry I closed the older threads, but this is a huge improvement with all the garbage I'd been seeing!]

[Update 2 - just had to wait a couple of days - spam as bad as ever. I closed some more threads, we'll see.]

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Arthur, you have now closed

Arthur, you have now closed the three recent Tiljander-related threads, notwithstanding that productive discussion was continuing on the latest one, "Michael Mann's errors." Per your remarks on the Hockey Stick, I would like to reference my earlier comment, "Arthur, you conclude your...". That brings up items that you might want to address when the moment is right, given your original "terms of reference" for these posts.

Regarding Tiljander, I also refer you to my website, which contains complete (or nearly so) compilations of literature, data archives, and blog posts on the matter of the use of the Tiljander proxies in Mann08 (PNAS).

AMac, any chance any of my

AMac, any chance any of my comments will get through on your site?

MikeN, I'm mystified.

MikeN, I'm mystified. Blogger says that my blog's comments are unmoderated and open to all, requiring only the completion of a word-verification step. There's no record of rejected or deleted comments, and no queue. Can you email your remarks to AMac.contact at gmail dot com for me to post?

In other news, Gavin Schmidt has a productive exchange with Keith Kloor and, to a previously-unheard-of extent, with dissenters from the AGW Consensus position. Gavin's Perspective. My Tiljander For Beginners summary is at spot #127.

My initially testy exchange with 'scientist' at ClimateAudit's thread The No-Dendro Illusion has turned very productive. Some other commenters have contributed some gold, as well, including PDFs of two recent paleolimnology dissertations from Finland, and a recent analysis of multi-century varved sediment records from another Finnish lake.

I am now harboring doubts that any of the Tiljander03 data series can be shown to be suitable for use as paleotemperature proxies, even the pre-1720 portions. Assuming those doubts turn out to be justified, defenders of Mann08 should think through the implications before breaking out the champagne. Such a finding would not be exculpatory in regards to the authors' conduct. It would further highlight the defects in their underlying science, including the aspects that Gavin alluded to at RealClimate.org last week, in the comments to the Tamino HSI review thread.

I just noticed your comment

I just noticed your comment on EIV Martin. I wasn't saying the code itself is a mess, but the analysis of the results.
Apparently, the EV method ends up with the same proxy having negative and positive weights at different periods of time.

Mike, the EIV method is

Mike, the EIV method is significantly more complex than CPS. Weights may well be positive or negative depending on other proxies present. There is no obvious interpretation for these coefficients individually.

I suggest you read Tapio Schneider, to get a "feel" for the method.

Arthur, I the discussion of

Arthur,

I the discussion of my mistake I made it clear that I preferred to do my defense at ClimateAudit, where I had assurances that my comments would always make it through.

Your rejoinder to me was that I had no basis for fearing censorship at other sites, such as your site. I find it odd therefore that you should close threads where we are asking you simple questions.

Um, your hero closed the

Um, your hero closed the thread that attacked me. I feel no compunction about managing this blog to my own satisfaction. You may ask questions, I may perfectly happily choose not to answer any of them. Hope you're ok with that.

My recollection is that

My recollection is that McIntyre closed that thread due to an escalating back-and-forth dispute in the comments that had nothing to do with you, Arthur. "Skeptics" arguing with one another--a negative example, but a predictably common occurrence for a fractious bunch.

And I agree that you should have the ability to respond to criticisms, preferably there. You got a fair number of licks in, and have this site as well, fortunately.

"Hero"? I dunno. McIntyre's activities would be unnoticed and superfluous, if paleoclimatology followed the normal customs of a physical science, rather than indulging in postmodern practices.

Defending the faux calibration of four uncalibratable proxies in the fifth-most-prominent peer-reviewed journal with an idea such as "I don't know, and it doesn't matter"? C'mon.

I don't believe I've

I don't believe I've "defended" it, or said "I don't know, and it doesn't matter". You're referring to Gavin, perhaps? My attitude is that I don't know whether it matters or not. Some people claim it does, some claim it doesn't. I need to understand the issue for myself, which will take some time and effort, an endeavor which I have already commenced on thanks to your persistence. But don't overdo it or I may get ticked off and give up.

> You're referring to Gavin,

> You're referring to Gavin, perhaps?

Gavin Schmidt and toto at Collide-a-scape, and Martin Vermeer, here.

> But don't overdo it or I may get ticked off and give up.

As you wish, it's your call. I've appreciated the opportunity to see if there are opposing issues on the subject of Mann08's uses of the Tiljander proxies that I hadn't considered.

Actually, the thread was

Actually, the thread was closed largely due to me posting in defense of Arthur Smith. The exchanges which followed were rather unsightly, a sort I have rarely seen at ClimateAudit.

After the thread was closed, the subject was basically left to rot. To this day, Steve McIntyre has not offered any correction for what he said. A number of false claims raised by other posters have not been retracted (my last post discussing them never appeared due to the spam filter, and I didn't bother remaking it).

While the affair is nowhere near on par with things done by Mann and his supporters, it is oddly reminiscent of them.

McI is a funhouse mirror

McI is a funhouse mirror version of Mann. Moderation excesses. Refusal to answer questions. Voice of God commentary. Equivocation.

But at least Mike publishes. At least Mike puts down his ideas and stands before them. Not just a blog full of high fiving and "lab notebook writing" for 5 years.

Abnormally careless? Arthur,

Abnormally careless?

Arthur, was I abnormally careless for a comment made on a blog? Seriously, I love the way you move the goal posts.

So if the whole field was careless and made basic math errors you would not have an issue with it?

Guess what, if mann was not abnormally careless then you damn the whole field.

Steve, your illogical

Steve, your illogical negative interpretation of anything I say does you a great disservice.

The two legs of climate "skepticism" are fundamentally the assertion that climate scientists are either fraudulent or incompetent. Various of you have made a case that sounds very close to fraud against Michael Mann, but then seem to keep backing away from it. I asked for the strongest example, and we have Tiljander, so I'll look into that. That's one set of goalposts - the "fraud" goalposts, shall we say. The implication is deliberate error: repeated, consequential, even after the error having been clearly communicated to the perpetrator.

The second set of goalposts concerns incompetence. Perhaps one, or many, of the researchers involved are particularly error-prone or simply clumsy or stupid in their handling of data. I haven't established to my mind exactly what criteria would clearly identify such a case, but that seems to be the one you are making now. Is that correct?

> Various of you have made a

> Various of you have made a case that sounds very close to fraud against Michael Mann, but then seem to keep backing away from it.

Arthur, be specific. Not "various of you," but actual names (okay, pseudonyms). You have repeatedly alluded to fraud, so you can be one. Don't count me in. This is a charge I have not made, and therefore have not backed away from.

So, who?

I know I for one have

I know I for one have consistently avoided the term "fraud." It seems too associated with "scientific fraud," something far more severe than anything I am willing to claim.

That said, I have been perfectly consistent with my accusations. I freely say Michael Mann has done shoddy work. I say issues arising from this show a fundamental problem in his work. I say he has intentionally withheld information showing problems with his work (verification statistics). I say he has lied about this information.

Now then, I'm sure I've said a number of other negative things about Michael Mann as this list isn't meant to be comprehensive. You can say what I describe amounts to "fraud" if you want. It doesn't matter to me. I think the accusations are perfectly damning no matter how you describe them.

Martin: Everyone may not like

Martin:

Everyone may not like to admit fault, but I don't think this is an equal trait. I think well over half of people on the net have a VERY hard time admitting wrong, and many scientists do as well. But they shouldn't.

When you do finally figure something out and realize you are wrong, you should be ABSOLUTELY clear to correct yourself and inform others of the new and changed position. Making opaque statements is unhelpful and mildly disengenuous. Note: I'm not slamming Mike in particulare...I've seen the same from Steve and others as well. But I consider it a real failing.

I agree that impact is important and I can ask for it when I want it. There is a value in asnwering the quesiton asked though. There's also a benefit of disaggregating issues. Maybe Clinton had sex with Monica (yes/no) and maybe it was OK (right/wrong). But they are two different issues. Responding on one, when the other is in question is non-helpful. If I do a mathematical modeling and have a question about one area, the issue of the IMPACT on the final answer is a different on ffrom the issue of the is the equation in the area off. You can actually evaluate both of those concepts. But responding on B, when A is in debate is just frustrating and happens all the time with idgit debaters on all sides of the INternet (left and right) and just makes the whole thing tiring and stupid.

You seem like a more straightforward type yourself.

I had typed up a response in

I had typed up a response in a thread earlier, only to find it closed when I hit "Submit." This thread wasn't around at the time, so I didn't get to post it. It seems worth posting now, even if it is a little late. From the rather lengthy post Arthur Smith made at RealClimate:

The fundamental foundation of all of that has to return to the one question that can be answered by science here: “is the hockey stick an illusion”? If you want a scientific discussion, that is the only question of relevance. And Tamino addressed precisely that question in his review here. The answer is, No.

I have two parts to my response to what Arthur Smith said. The first is, "You are wrong." Obviously, you cannot simply take Tamino's post as gospel. This is true of everything. One should always apply at least a little critical analysis when one reads. Unfortunately, if one does so, they will find Tamino's post is unreliable. I don't think anyone here wants to sidetrack things into a discussion of his post, but I think an example is needed. In that post, Tamino said:

As another example, Montford makes the claim that if you eliminate just two of the proxies used for the MBH98 reconstruction since 1400, the Stahle and NOAMER PC1 series, “you got a completely different result — the Medieval Warm Period magically reappeared and suddenly the modern warming didn’t look quite so frightening.” That argument is sure to sell to those who haven’t done so.

Tamino is making this up. Montford never made this claim. McIntyre discusses this here. The claim Tamino accuses Montford of making is in fact a claim Michael Mann made, and it is only selective quoting which allows Tamino to criticize Montford.

In other words, Tamino "cherry-picked" a quote, took it out of context, and misrepresented it. He then did an analysis of the claim he falsely accuses Montford of making, and disparaged him on the bogus issue. The only person who could fairly be criticized on this issue is Michael Mann, the one Tamino is seeking to defend.

My second part of my response to Arthur Smith's post is, "But so what?" Does it matter if Tamino's post was bogus? Does it even matter if the hockey stick is an illusion? No. Climate change isn't going to vanish if the hockey stick goes away. Carbon dioxide is still a greenhouse gas, and humans are still warming the planet. The hockey stick may be a powerful image for PR purposes, but as far as the core science goes, it means little.

The issue of the hockey stick isn't about science. Tamino's post isn't about science. Gavin's continued defense of Mann's work isn't about science. It is all about PR. Saving face. Looking good for the cameras. If any of it was about science, these people wouldn't be able to make bold claims which are obviously untrue, yet go unquestioned. Science cares about being accurate, about being correct. The hockey stick is about being "right."

How many times will these people be allowed to make things up before things change?

Goodness, Brandon, have you

Goodness, Brandon, have you read the PDF that McIntyre links to, referred to as Mann et al from November 2003 (response to M&M)?

MM do not list the number of indicators in their putative revision of the MBH network (which is
based on a complicated combination of original data from MBH98 and data substituted from
other sources). The reader must do a considerable amount of detective work, based on scrutiny of
the Tables in their pages 20-23 and the indicated data links, to determine just what data have
been eliminated from the original MBH network.

What McIntyre is posting is a graph that MBH made to try to recreate what McIntyre had done in the M&M article - it is certainly not a "reconstruction" in any normal sense of the word. Montford's interpretation and McIntyre's gloating over the whole affair, as far as I can tell, entirely justifies Tamino's commentary on this.

Have you got anything else that was actually wrong in Tamino's review?

I do not understand your

I do not understand your response. How does anything you said relate to Tamino falsely saying Montford made a claim? Why Mann made the figure he made doesn't matter. The point was he was the one who made it. The text in Montford's book makes it perfectly clear Mann was the source for it. This means Tamino grossly misrepresented Montford in his review.

It is simple:

1) Montford clearly said something.
2) Tamino claimed Montford said something else, possible only through selective quoting.

I can't see how anything in your post addresses either of these simple points. Do you actually dispute either of them?

Tamino quoted Montford. It's

Tamino quoted Montford. It's hardly "selective". Mann's pdf makes no mention of "Medieval Warm Period" or anything resembling the text Tamino quoted. Rather it says, on this subject:

deletion of key early proxy information produces anomalous warming in
the 15th century at odds with the reconstructed cold conditions of the period by MBH98 and
virtually all other published Northern Hemisphere temperature reconstructions.

The question is 15th century warming. The 15th century is well after what's generally considered the end of the MWP (to 1250 AD), and a bit before the start of the Little Ice Age. To claim that Montford's phrasing, that "the Medieval Warm Period magically reappeared" was what Mann intended in that document is a gross distortion of the facts. I find it astonishing you cling to this claim. Find something better, please, if you really think Tamino was wrong about anything.

The phrasing is found on pp

The phrasing is found on pp 103 of HSI. Apparently this was McIntyre's claim. Montford seems to say that Mann claimed it was a combination of incorrect method and dropping of the two PC's. McI (as told to Montford) then claims that only the dropping of the two proxies was necessary to get his results.

I also always found it rather odd that McI was looking for a MWP in a paper which went only to the 15th century. Did anyone else ask themselves this question?

Mann response to McIntyre

Mann response to McIntyre included making a figure. Montford said of it:

Without realising that he’d done it, Mann had inadvertently shone a little light on another murky corner of his famous paper. To McIntyre, what made Mann’s response most interesting was not the fact that Mann had used an undisclosed methodology, but the fact that if you left out just two of the proxy series – the Stahle and NOAMER PC1s – you got a completely different result – the Medieval Warm Period magically reappeared and suddenly the modern warming didn’t look quite so frightening. What this meant was that Mann’s result – that the Medieval Warm Period didn’t exist – seemed to rest on just a tiny fraction of his data.

Tamino said:

As another example, Montford makes the claim that if you eliminate just two of the proxies used for the MBH98 reconstruction since 1400, the Stahle and NOAMER PC1 series, “you got a completely different result — the Medieval Warm Period magically reappeared and suddenly the modern warming didn’t look quite so frightening.” That argument is sure to sell to those who haven’t done so. But I have. I computed my own reconstructions by multiple regression, first using all 22 proxy series in the original MBH98 analysis, then excluding the Stahle and NOAMER PC1 series.

The claim Tamino discusses, that removing the Stahle and NOAMER PC1 series causes the MWP to reappear is Mann's work. Mann made the figure showing it. Neither Montford nor McIntyre made the claim. They simply discussed what Mann himself claimed. It makes no sense to fault Montford for something Mann claimed.

Now then, you can disagree with Montford using the phrase "Medieval Warm Period magically reappeared" because the MWP was actually earlier than the what he is discussing. Quite a few people do the same thing, and it might be an issue worth discussing. However, it has no bearing on this issue. This issue is simple, only requiring us look at two questions:

1) What did Montford say?
2) What did Tamino claim Montford said?

Tamino quoted Montford's

Tamino quoted Montford's exact words, it's what he said. Montford did not put those words in any sort of quotation marks to indicate they were somebody else's words. He did not preface or follow up with a statement that the claim represented by those words was wrong. The statement is Montford's. If it was supposed to be "what Mann himself claimed", then it is a clear misrepresentation of what Mann did in several ways:

* Mann was not talking about the Medieval Warm Period
* Mann et al's figure was intended to try to reproduce MM's figure, it was not a "result" promoted by Mann - in fact later on the PDF explains exactly why that section of the graph in those conditions is entirely unreliable.
* As far as I can tell, Mann's PDF did not state the figure was generated just by leaving out "two of the proxy series – the Stahle and NOAMER PC1s" - for one thing it referred to *three* different data sets that were different, not two, and I'm not clear on what the relationship is between "NOAMER PC1s" and "the entire dataset of 70 Western North American (WNA) tree-ring series available between 1400 and 1600" which Mann refers to.

The words are Montford's, not Mann's. The claim is Montford's, not Mann's. And Tamino showed Montford's claim to be false.

This response will be in two

This response will be in two parts. The first will deal with who said what, while the second will deal with questions of whether what was said was correct. With that stated, let's look at what Montford said:

To McIntyre, what made Mann’s response most interesting was not the fact that Mann had used an undisclosed methodology, but the fact that if you left out just two of the proxy series – the Stahle and NOAMER PC1s – you got a completely different result – the Medieval Warm Period magically reappeared and suddenly the modern warming didn’t look quite so frightening.

Clearly Montford is not the source of this claim. He is discussing the results in a figure created by Mann. It does not matter if quotation marks were used. It does not matter if the words involved were from Montford. Tamino quoted Montford mid-sentence, starting at "if." Look at what immediately preceded it:

To McIntyre, what made Mann’s response most interesting was not the fact that Mann had used an undisclosed methodology, but the fact that...

He is repeating what Mann himself showed (through the figure). The worst you can fault him for is he accepted Mann's figure as accurate, when apparently it was not. He accurately described the result shown in Mann's figure. He did not create it.

Now then, if Tamino wanted to criticize Montford for repeating an incorrect claim, that is fine. If Tamino were to say, "Montford uncritically parroted an inaccurate result shown in a figure created by Mann," there would be little problem. However, that is not what he did. He said Montford made the claim, criticized Montford, and never once mentioned the fact Montford was only discussing what Mann himself showed.

Montford's immediately

Montford's immediately preceding phrase is "the fact that". But his "fact" was wrong, on at least several counts. It was his paraphrase, and his responsibility to determine whether what he stated was a "fact" was indeed a fact. Nobody else has been going around making this particular statement in public - certainly Mann has not. The claim is Montford's, nobody else's.

Mann made a figure. The

Mann made a figure. The figure was wrong. Montford discussed the figure. You blame Montford for his discussion being wrong. You can take that route if you want, but I don't think you will convince many people Tamino criticizing Montford's discussion while hiding the fact the source for it was Mann's own work shows Tamino's post is reliable. The best you can hope for is maybe disingenuous. It certainly shows you cannot simply take Tamino's guest post at face value, which is the point I was making. The quote of yours I was discussing was this:

The fundamental foundation of all of that has to return to the one question that can be answered by science here: “is the hockey stick an illusion”? If you want a scientific discussion, that is the only question of relevance. And Tamino addressed precisely that question in his review here. The answer is, No.

Now then, I had simply been intending to show this comment was untenable as Tamino's post wasn't reliable. However, it seems impossible to get anyone to admit any fault on Mann's part, including something like, "Mann's figure was wrong." So I am going to try a more direct tactic. Let's discuss science:

People say the hockey stick is an "illusion" because it depends entirely upon very small amounts of data, data which isn't even trustworthy due to problems with it. In reference to the original MBH works, they say the conclusions rest entirely upon a small amount of tree ring data. In your post at RealClimate Arthur Smith, you claim Tamino shows the hockey stick is not an "illusion." So tell me, what in his post shows the criticism of the original MBH works are wrong?

Tamino says if you remove Stahle and NOAMER PC1, you still get a hockey stick. The critics don't care. They weren't talking about Stahle. They were talking about Gaspe all along. They say if you remove Gaspe and NOAMER PC1, you don't get a hockey stick. What in Tamino's post shows this is untrue? Or how about Mann's 2008 paper, where people say if you remove those tree rings and Tiljander, you don't get a hockey stick. What in Tamino's post shows this is untrue?

I was trying to just get you to apply some critical thinking to Tamino's post, but apparently it didn't work. So now I am challenging you directly. You made a bold factual claim. You claimed the hockey stick isn't an "illusion." If you are going to hold Montford to the standards you discuss, I think it is time you hold yourself to some too.

But remember, Gavin already admitted the hockey stick goes away when you remove the questionable data.

This is something of a

This is something of a tangent, but I want to throw this out there because it can catch people up. When people talk about the removal of Gaspe and NOAMER PC1, there is an important point lost. Gaspe is included in NOAMER PC1 (as cana036). However, MBH also used Gaspe as an individual proxy (as treeline11.dat). It is obviously wrong for Gaspe to be double counted like that, but it was.

Anyway, It is worth remembering when discussing what is kept and what is removed.

Well, if this is true, this

Well, if this is true, this again tells against Montford's interpretation that just 2 series were removed in Mann's figure. Mann said they had removed "the entire dataset of 70 Western North American (WNA) tree-ring series", which by your claim here, must have also included the Gaspe data.

It seems to me that you are simply parroting what McIntyre and Montford have been saying without actually understanding it for yourself. If you're just going to quote McIntyre, provide a url to the relevant page and be done with it. If you are actually going to provide some original thinking of your own on the matter, that of course is welcome. I don't see a lot of it on this subject yet.

I absolutely agree "Mann's

I absolutely agree "Mann's figure was wrong" if by that you are referring to the figure that McIntyre posted that seems to be from some response Mann et al sent based on MM 2003. I don't believe that figure was published anywhere - was it? Mann doesn't even stand by that figure in the text of the PDF, he states specifically why it was bogus (RE statistics were terrible).

But if somebody anywhere says "the fact that ..." they are clearly standing by the factuality of the statement they make, irrespective of the source of the claim. Montford was making a public claim that Mann's work, removing two proxies, showed a "Medieval Warm Period". It does no such thing.

Sure, Tamino didn't discuss the full context of Montford's claim - but that has no bearing on whether Montford was right or not. Montford was, plainly, wrong, as we've now found on more than just the count Tamino demonstrated.

Did Montford's book discuss removing "Gaspe and NOAMER PC1"? If not, how was Tamino supposed to address a claim that wasn't in the book? Who are these "critics" who say what you claim, before McIntyre's post that came *after* Tamino's review? And Tamino did discuss the Gaspe data later in his post; was his discussion of the dating issue not based on what Montford wrote?

And where did "Gavin already admit[...] the hockey stick goes away when you remove the questionable data?" You're doing just like Montford, putting words in other people's mouths. Reference your claims, be precise, and specific. The vague accusations and excuses need to end.

Here is the second part of my

Here is the second part of my response. Accepting that Mann was the source of the results discussed by Montford, three questions are raised on the accuracy of his comments. The first thing I will note is none of these issues are raised in Tamino's guest post at RealClimate. As such, none of them could possibly justify anything he said. I am discussing them because they are issues worth covering, not because somehow they would justify trusting Tamino's post. Nothing in this part of the exchange has any relevance to the other part, and it is important to keep that in mind.

Before discussing the issues, I want to correct something. I accept my wording earlier may have been less clear than it should have been, and it is possible to take my comments as saying Mann endorsed what Montford said. I did not mean to suggest this, and I do not think it is true. My only intention was to show Montford's claims were discussing the results shown by Mann. With that said, the first issue raised:

* Mann was not talking about the Medieval Warm Period

I agree. It is an unfortunate truth in the blog world that many people inaccurately refer to a (supposed) warm period around 1400-1500 as the Medieval Warm Period. This is incorrect, and the conflation is regrettable. While it is a relatively minor error, it is an error nonetheless.

* Mann et al's figure was intended to try to reproduce MM's figure, it was not a "result" promoted by Mann - in fact later on the PDF explains exactly why that section of the graph in those conditions is entirely unreliable.

Nobody has said otherwise. Montford never claimed removing those series created a good reconstruction. He never said it was a better result. He certainly did not say Mann endorsed this as a valid reconstruction.

Montford simply said Mann's response showed removing the two proxies created a warm period (which he incorrectly referred to as the MWP) equitable with the modern warming shown in Mann's work. Whether or not you get good validation scores after removing that data is completely irrelevant to what he said.

* As far as I can tell, Mann's PDF did not state the figure was generated just by leaving out "two of the proxy series – the Stahle and NOAMER PC1s" - for one thing it referred to *three* different data sets that were different, not two

The third series referred to in the caption of Mann's figure was a series which didn't "come into play in the 1400 step," as mentioned by Steve McIntyre. The series in question only goes back to 1500, so it obviously cannot have an effect on the elevation shown prior to 1500.

and I'm not clear on what the relationship is between "NOAMER PC1s" and "the entire dataset of 70 Western North American (WNA) tree-ring series available between 1400 and 1600" which Mann refers to.

This isn't really a question of the accuracy of Montford's claims, but it is an understandable confusion. Quite simply, they are referring to the same thing.

You say they are referring to

You say they are referring to the same thing. Please provide a reference that explains this. The Mann PDF refers to more than one PC associated with the "Western North American tree-ring series", so that sounds like more than one proxy series (evidently it's 70 series in original form...)

Further to this, your claim

Further to this, your claim that:

Montford simply said Mann's response showed removing the two proxies created a warm period (which he incorrectly referred to as the MWP) equitable with the modern warming shown in Mann's work. Whether or not you get good validation scores after removing that data is completely irrelevant to what he said.

is again really really stretching things. In scientific terms, if a piece of data does not have "good validation scores" it is essentially meaningless. Specifically, the numerical uncertainty associated with the data has to be considered if you are using it for any sort of comparison. As you say, Montford was explicitly comparing the bogus results in Mann's figure (mischaracterizing along the way) to modern warming. But it is not comparable because the uncertainty in that non-reconstruction is so huge. I don't know what the numerical uncertainty level would be, but Mann's RE statistic indicated an order of magnitude problem, so the actual value of the curve if you remove whatever they did relative to modern temperatures cannot be determined, according to what I understand Mann to be saying there, to many Celsius degrees. It could be the "real" value would be 5 degrees colder than modern, or 10 degrees warmer, if the uncertainty is that large. So Montford's explicit claim about what Mann had shown was false on these grounds as well.

If Montford wanted to talk about what Mann had done in the response to M&M, he could have:
(a) directly quoted Mann's text, for example:

"we have confirmed that elimination of the critical datasets (1)-(3) alone from the MBH98 network, which account for the overwhelming majority of proxy data used during the interval AD 1400-1500, yields the spurious result obtained by MM."

Nobody could possibly have complained if that full quote had been used.

(b) selectively quoted from Mann's text to give a differing impression:

"we have confirmed that elimination of the critical datasets [...] yields [...] anomalous warm values during the 15th century"

and Tamino in that case ought to have pointed out the problem with the selective quoting, rather than the problem with the claim which is still presumably correct in whatever context Mann meant.

(c) paraphrased Mann's text using his own distortions, but prefacing with "Mann said" for example:

... Mann said that if you left out just two of the proxy series – the Stahle and NOAMER PC1s – you got a completely different result – the Medieval Warm Period magically reappeared and suddenly the modern warming didn’t look quite so frightening.

which Tamino in that case ought to have pointed out that was not what Mann said at all.

(d) or, as he did, prefacing his distortion with "the fact that".

By choosing (d), Montford made the claim his. Tamino's response was perfectly reasonable, and if that's the worst complaint you have about what Tamino covered, I consider it extremely weak.

I left this comment on

I left this comment on Tiljander and Mann08 in the current Climate Audit thread:

Mann08′s authors’ self-inflicted bind

The last criteria in Arthur

The last criteria in Arthur Smith's fraud definition is whether the mistake was repeated even after pointed out, or did they not do it again. In general, Mann seems to accept Steve's criticisms while denying that Steve is correct. We don't see decentered PCs, Climategate emails warning against using PC analysis at all, and now more code release.
However, in the 2009 Mann et al, we see that Tiljander proxies passed both correlations, as shown in the 1209 proxynames.xls file. Still looking for the code for the paper.

Looking at the code for Mann

Looking at the code for Mann 09, at first glance it appears that the code is 'blind to the sign of the predictor.' The proxy should still not be used due to contamination issues.

Hello Arthur, May I just add

Hello Arthur,

May I just add my thoughts on the Tiljander kerfuffle. I have come to the conclusion that a mistake was made by Mann et al in the 08 paper. They simply did not follow the procedure as described. An essential part of the method was the screening of the proxies prior to calibration and reconstruction. They are quite clear that the particular test is dependent on a priori knowledge of the sign of the correlation between the proxy values and the temperature. In the case of the Tiljander varves the only source of a priori knowledge comes from the original Tiljander paper which has never been contested in any literature that I am aware of.

As far I know Tiljander assigned a positive correlation to Darksum, a negative correlation to Lightsum and X-ray density. No correlation was given for Thickness. Clearly, Mann et al were quite free to contest these assignments if they wished to, and use other correlations for the screening tests but I cannot believe that they would have done this without any discussion in the paper. It certainly seems from the code that all these varves were actually given the test appropriate for a positive correlation and I can only conclude that this was an accidental mistake. Had the only known a priori tests been applied correctly the Lightsum and X-ray density would have failed screening and excluded from further consideration. The correct test for Thickness would have been the two sided one but it would have passed that anyway.

Everything else then follows from this initial error in the screening procedure. Of course, all four varves did turn out to have a positive correlation during the instrumental period and so all four were included in the construction using the positive correlation leading to all the chatter about them being upside down.

As I am just a retired electronics type I cannot offer any informed opinion about the correctness or otherwise of the original Tiljander correlations or the extent to which the acknowledged contamination during the instrumental period may have led to faulty calibration, including sign, of some of the proxies.

It would certainly be valuable to find out whether subjecting all four proxies to the screening test for positive correlation was an accident or intentional but unexplained.

Regards,

Jorge

My guess (perhaps someone who

My guess (perhaps someone who has looked at the data files can verify) but my understanding is that proxies classified as lake varves were considered to have an a priori positive correlation. If this is true then lightsum and XRD should have been classified as something else. Seems like a simple mistake to make.

That is how they are

That is how they are classified, and there is another classification available for a priori negative correlation.

Simple mistake to make, not so simple is the response given by Mann when Steve published on the point.

The claim that ‘‘upside down’ data were used is bizarre. Multivariate regression methods are insensitive to the sign of predictors. Screening, when used, employed one-sided tests only when a definite sign could be a priori reasoned on physical grounds.

While there is a separate contamination issue, even without that, the plain reading of this response is that there is no way data could be used upside-down except for screening with one-sided tests, not used in this case.

Tiljander in fact does use one-sided test, which makes the last sentence useless. Perhaps the second line refers to EIV processing, but otherwise it is also not responding to the charge, as in the case of Tiljander, his code is not blind to the sign of the predictor.
What type of response is this to an accusation of upside-down usage?

I think all the varves were

I think all the varves were in the ID4000 category. The ID number was used in the code to determine which of the screening tests to employ, so anything with an ID of 4000 was checked for positive correlation.

I really don´t want to speculate on how all the Tiljander proxies came to be lumped together, but not placing Lightsum and X-ray density in a separate subgroup for screening seems to have been the root cause of all the claims that they were used upside down.

In reply to such claims Michael Mann replied "The claim that ‘‘upside down’ data were used is bizarre. Multivariate regression methods are insensitive to the sign of predictors. Screening, when used, employed one-sided tests only when a definite sign could be a priori reasoned on physical grounds. Potential nonclimatic influences on the Tiljander and other proxies were discussed in the SI, which showed that none of our central conclusions relied on their use."

This is, of course, all true but seems not to cover the possibility that the wrong one sided screening test was used. By wrong I mean that it was not consistent with the a priori physical basis as given by Tiljander. By using a sceening test that is inconsistent with Tiljander, the door is left open for a reconstruction that is indeed upside down with respect to the Tiljander interpretation.

As things stand Mann et al have produced a reconstruction for these two proxies that is upside down with respect to Tiljander. I find it curious that this upside down argument has been going on since the 2008 paper was published without any resolution. There is endless room for debating the merits of the data or its interpretation but this particular question could be settled in minutes if Mann et al would say it was a simple error and the two reconstructions will be removed or would explain their reasons for disagreement with the physical basis put forward by Tiljander. The latter may be more difficult as Kaufman has recently issued a correction to a paper using these varves that brings the physical interpretation into line with that of Tiljander.

Okay, there are too many

Okay, there are too many separate threads of conversation now. All I wanted was to show was pointing to Tamino's post as some sort of gospel response to criticisms of the hockey stick was a bad thing to do. I gave a simple example without realizing it would turn into some huge mess. Tamino criticized Montford for something Mann showed, which Montford discussed. Montford's took Mann's figure at face value, and now he is being criticized for it (due largely to a stupid semantic point). Personally, I think this shows Tamino's review is unreliable, as the best I think it could be called is disingenuous. If someone can look at this point and feel no hesitance when reading Tamino's post, so be it. I don't think anyone could do so without being rather biased, but perhaps people would just say the same of me. In any event, this started because of the comment:

The fundamental foundation of all of that has to return to the one question that can be answered by science here: “is the hockey stick an illusion”? If you want a scientific discussion, that is the only question of relevance. And Tamino addressed precisely that question in his review here. The answer is, No

I have no idea what the basis for this claim was supposed to be, and Arthur Smith certainly hasn't said it. Tamino's post doesn't address the primary criticisms of the hockey stick, so it certainly could not show them wrong. Presumably this means Smith has something other than Tamino's post to go on, though I am at a loss for what it is. My suspicion upon reading that comment was the basis for his claim was faith in the people supporting the hockey stick, which is why I tried to show that sort of faith is unfounded. I now regret my approach. It seems impossible to reach any agreement on that point, and as such I am going to drop it as a source of irreconcilable differences.

So instead I am going to switch tactics. I'm going to focus on the science. I will outline a few basic points, some fundamental criticisms of the hockey stick. We can discuss these specific points, and see where we agree and disagree. If the hockey stick is not just an illusion, an artifact of bad science, these points would need to be shown false.

With that said, I accept I have a responsibility to support the things I said on the previous subject, even if I no longer wish to pursue the subject itself. Given the spread out nature of the exchange, I'm not sure of all the issues which require my attention. I will make an effort to support the things I said. If there are any issues I miss which anyone would like covered, just let me know.

You say they are referring to

You say they are referring to the same thing. Please provide a reference that explains this. The Mann PDF refers to more than one PC associated with the "Western North American tree-ring series", so that sounds like more than one proxy series (evidently it's 70 series in original form...)

This didn't seem like an important point so I didn't put much thought into it (it was years ago, and there isn't any reason to doubt what was done now, if there ever was). In re-reading my post, I see I misspoke. NOAMER is made up of 70 sites (it stands for North American tree rings), and NOAMER PC1 is created from it through principal component analysis. You asked after NOAMER PC1, not NOAMER, a distinction I didn't pay attention to at the time. I apologize for the slip-up, but I really don't handle multiple threads of dialogue well.

Anyway, that should clarify the relation between *NOAMER PC1* and the "Western North American tree-ring series." Mann was referring to NOAMER, of which NOAMER PC1 was a subset. If you really want a references for this, or more detail, I can track down whatever you need. Mann's data files are (now) available, as is his code, so we can go into as much detail as we need.

Did Montford's book discuss removing "Gaspe and NOAMER PC1"? If not, how was Tamino supposed to address a claim that wasn't in the book? Who are these "critics" who say what you claim, before McIntyre's post that came *after* Tamino's review? And Tamino did discuss the Gaspe data later in his post; was his discussion of the dating issue not based on what Montford wrote?

Unfortunately, I do not possess Montford's book, so I cannot say exactly what is and is not discussed. However, I can answer your second question. If Tamino's post was only discussing Montford's book, and if Montford's book never discussed removing "Gaspe and NOAMER PC1" (something I doubt), then there was nothing technically wrong with not discussing the removal of those two. However, I was not raising the issue of whether or not Tamino's post was wrong on this issue. I was pointing out Tamino's remarks did nothing to disprove specific criticisms of the hockey stick.

As for the issue of removing Gaspe and NOAMER PC1, the issue has been discussed many times in many different venues, even at Tamino's blog.
It has been discussed in peer-review literature, including work cited by authors at RealClimate. In other words, anyone looking into whether or not the hockey stick is an "illusion" would be expected to have come across the issue. A quick browse of my saved pages produced this page as an example, and I can dredge up more if you need.

And where did "Gavin already admit[...] the hockey stick goes away when you remove the questionable data?" You're doing just like Montford, putting words in other people's mouths. Reference your claims, be precise, and specific. The vague accusations and excuses need to end.

Would you please stop accusing me of making "vague accusations"? I have been more than willing to provide you specific details to my accusations each time I have made them, a point you know fully well. Any time I have been vague, I have been willing to provide any details or information needed to back up what I say.

In this case, I assumed you knew what I was talking about because it has been discussed on this site. With how little traffic there is to your blog, I assumed you had read this or this post. Both of those posts refer to Gavin's inline response to this comment. Gavin says Mann's 2008 work does not validate back more than 500 years if you remove the questionable data. The hockey stick requires a flat shaft going farther back than that, thus Gavin's comment means the hockey stick doesn't validate without the questionable data. In other words, it goes away.

As always, if there is anything I have said anywhere which needs clarification or support, let me know and I will provide it. I'm sure I missed some things here.

Brandon, perhaps the

Brandon, perhaps the fundamental issue is I do not understand what your definition of "the hockey stick" is. You say:

The hockey stick requires a flat shaft going farther back than [500 years]

and yet MBH 1998, which I thought was the whole origin of this discussion, only goes back 600 years. So MBH 1998 was not showing a "hockey stick"? Or it was not "the hockey stick"?

If we could at least agree on what "the hockey stick" is, perhaps we'll get somewhere. It would certainly be interesting to me to find out that MBH 1998 had nothing to do with "the hockey stick"!

To me, a "hockey stick" refers to any graph that may meander up and down a bit but that ends in an upward (or perhaps downward!) accelerating slope with a final value clearly above the earlier "meander" range. It could be a graph of just a few hundred years, or a graph of hundreds of thousands of years. It could be a graph of temperatures or of human population or of CO2 levels. "The hockey stick", well, I'm really not sure what that is. I thought we were talking about MBH98, but apparently not?

When I say "the hockey

When I say "the hockey stick," I am referring to the one popularized in climate science. It originated from work by Michael Mann and coauthors in a 1998 temperature reconstruction. This reconstruction went back to 1400. A paper published the next year (1999) extended the previous reconstruction back to 1000. These papers are referred to as MBH98 and MBH99, or collectively referred to as MBH. This hockey stick received a great deal of notice due to its inclusion in the IPCC Third Assessment Report, where it was said:

[T]he rate and duration of warming of the 20th century has been much greater than in any of the previous nine centuries. Similarly, it is likely that the 1990s have been the warmest decade and 1998 the warmest year of the millennium.

This is what started the hockey stick controversy. That is "the hockey stick." You say:

To me, a "hockey stick" refers to any graph that may meander up and down a bit but that ends in an upward (or perhaps downward!) accelerating slope with a final value clearly above the earlier "meander" range.

I agree with this, though I feel "clearly above" deserves emphasis. Gavin told us removing Tiljander and tree rings "doesn't matter," pointing to this figure. However, the slope at the end of that figure (for the line with the data removed) does not end "clearly above the earlier" values. In fact, it ends below them. From this, we (I presume) both agree it is not a hockey stick. However, it seems Gavin does not. I'm not sure how he reaches his conclusion, but it doesn't seem to be based on the definition you and I are using.

With all of those points

With all of those points covered, hopefully we can discuss some of the core issues. Most of what is at issue with the hockey stick is actually pretty simple. Here are three claims raised against the hockey stick which are pretty fundamental to understanding the hockey stick controversy.

1) The conclusions of Mann's original works (MBH 98/99) depend entirely upon a limited amount of tree ring data.
2) The conclusions of Mann's 2008 paper depend entirely upon the inclusion of Tiljander and tree ring data.
3) The correlation between the data referred to in points 1 and 2 and global temperatures is questionable.

These are simple and clear criticisms which have been leveled against the hockey stick. You said the hockey stick is not an illusion. To maintain that position, you must dispute those criticisms. I can provide any information you need on any of those points (or on a number of other points), but it still comes down do a simple question.

Do you dispute those three points?

On 2), the central

On 2), the central irreconcilable problem of Tiljander remains.

* Mann08's methods require that every data series be calibrated to the 1850-1995 instrumental record, but:

* Since any climate-related information in these data series has been overwhelmed by massive contamination due to local land use and water pollution, it is impossible to calibrate the Tiljander proxies to the 1850-1995 instrumental record.

* Therefore, the Tiljander proxies must be removed from Mann08's analysis. If the employment of the Tiljander proxies in any way seems to strengthens Mann08's analysis, then that analysis must have big, big problems.

Defenders of the vigor and rigor of Mann08's science will sing, and they will dance. They will not forthrightly consider facts. They will not apply the tools of logical inquiry to this question. They cannot: if they do, they will cease to be defenders of Mann08. It can only be upheld on advocacy and policy grounds. The science is indefensible.

Latest example: Gavin Schmidt, again.

Yes, I dispute all three

Yes, I dispute all three points. I am not well-versed in "the hockey stick", in fact I was not even willing to let it be discussed here (I deleted comments on the subject) until AMac convinced me to discuss the Tiljander issue. However, from what I have read now, your points are simply wrong:

1) MBH98/99 did not depend on a "limited amount of tree ring data", but rather a *substantial quantity* of tree ring data. That was the bulk of their analysis, as outlined in the PDF McIntyre pointed to. 70 datasets (plus ?). That's not "limited".

2) As Gavin Schmidt pointed out in the quotes you have referenced, Mann's conclusions back to year 1500 are solid independent of Tiljander and tree rings. The conclusions to earlier dates are not. So the claim that all his conclusions depend *entirely* on those datasets is wrong. The conclusions about early times do, yes - obviously because you are removing a substantial portion of the early proxy data by removing those datasets. It is not a "limited amount" of data that is being removed in doing these, it is the bulk of the relevant data. Nobody would expect conclusions to hold under those conditions. That hardly makes those conclusions an "illusion"!

3) The correlation of Tiljander with temperature is certainly questionable, I agree, and I'm putting some effort into understanding that. The correlation of tree-ring data with temperature, however, is as far as I can tell extremely sound. Anybody can "question" it, so by that definition I suppose it's "questionable", but in general I'd stake a lot more trust in those who rely on tree ring data than in those who "question" it, and I've found nothing in the discussion so far to shake that opinion.

1) This point is wrong

1) This point is wrong several counts. First, you say "70 datasets." This is incorrect. There is only one dataset here, NOAMER. It contains 70 series. In the paper you reference it says, it refers to "the entire dataset of 70 Western North American (WNA) tree-ring series available between 1400 and 1600." We are only talking about one proxy here, and it is only one of a number of proxies used by MBH.

Second, you rely upon a comment in that PDF for your information on what criticisms are talking about. Going solely on Mann's description of criticisms would be a bad idea, but it is even worse when you consider he said, "MM appear to eliminate...." This is not a statement of what was done. At best, it is an "impression." Unsurprisingly, it isn't correct.

There are 70 series in the NOAMER network. Principal component analysis was used to group these 70 series into a smaller number of series (PCs). How those PCs are calculated (non-centered or centered) changes how the PCs get grouped. Once the tree ring series are grouped into PCs, a certain number of them are kept for the actual analysis. In the MBH, two PCs were kept (PC1 and PC2). Those two series were combined with 20 other series to create MBH's final work. That means there were 22 series, of which NOAMER contributes to two (other series come from things like ice core samples). Now then, if you remove PC2, the results don't change. Things only change if you remove PC1. If you remove PC1, you get high 15th century temperatures. Keep it in and you don't.

This means the hockey stick shown in MBH relies entirely upon PC1. But we can be more detailed than that. Rather than looking at PCs, we can look at the series themselves. If we do that, we find of the 70 series in the NOAMER network, only 20 matter. If you remove those 20 tree ring series (commonly referred to as "bristlecones"), you don't get the hockey stick. If you are really curious, a list of which series matter can be found here.

To be clear, MBH's conclusion relies entirely upon 20 tree ring series. That's all. And as though that wasn't bad enough, MBH98 even said, "On the other hand, the long-term trend in NH is relatively robust to the inclusion of dendroclimatic indicators in the network...."

2) We are talking about the validity of the hockey stick. The abstract of Mann's 2008 paper ends with:

Recent warmth appears anomalous for at least the past 1,300 years whether or not tree-ring data are used. If tree-ring data are used, the conclusion can be extended to at least the past 1,700 years, but with additional strong caveats. The reconstructed amplitude of change over past centuries is greater than hitherto reported, with somewhat greater Medieval warmth in the Northern Hemisphere, albeit still not reaching recent levels.

What interests me is, "Recent warmth appears anomalous for at least the past 1,300 years whether or not tree-ring data are used." We now know this is only true if you include Tiljander, something which cannot be justified. If you remove Tiljander, this conclusion listed in the abstract is no longer true. Word it however you want, that is the point at hand. If you want me to use a different wording due to semantics, I can. However, it doesn't seem important. Finally, you make a remarkable claim:

It is not a "limited amount" of data that is being removed in doing these, it is the bulk of the relevant data. Nobody would expect conclusions to hold under those conditions.

You made a similar claim about MBH's original work (which specifically claimed to be robust to the removal I discuss). Unfortunately, in neither case did you provide any support for what you said. It seems to contradict Gavin's remark, who said it "doesn't matter" if you remove that data. He seemed to expect what you say nobody expected. Personally, when I hear 1,209 data series were used in Mann 2008, I don't expect to find out the conclusions listed in the abstract go away when you remove something like 30 data series.

How do you think people would react if they read in an IPCC report, "We conclude recent warming is anomalous over the last millennium based upon a handful of trees and some data which was grossly misused"? Because that's what we have here.

3) I'm too tired from typing up the rest of this to go into detail on this point right now. For now, I am just going to list two points. The first point is tree ring series used to create the hockey stick do not (necessarily) correlate to local temperatures. Tree rings are commonly included regardless of their correlation to local temperatures. You have to realize while tree rings can be correlated to local temperatures, they can also be correlated to many other things (especially water supply).

The second point is trees like bristlecones can get spurious growths due to things like recovering from damage. Even if the tree rings were correlated to temperature, you could get large spikes due to things like this. These spikes would be interpreted as elevated temperatures, even though they had nothing to do with temperature.

Incidentally, I just remembered an NAS panel said, "[S]trip-bark’ samples (bristlecones) should be avoided for temperature reconstructions" back when it and the Wegman report were commissioned.

There is *way* too much

There is *way* too much detail in your comment that I am simply not interested in investigating. I'm sorry I don't trust what you say on this, but I don't. McIntyre pointed to a PDF in support of his and Montford's claims, but as far as I can tell that PDF contradicted what McIntyre said. Here you appear to be simply spouting McIntyre-speak (once again without providing *any* references) that it doesn't look like you've really investigated or understood for yourself. I'm sorry, but I just do not trust it, given my previous experiences with McIntyre's misrepresentations, and what seems to be a clear misrepresentation in this case as well.

You will not convince me of anything further on this without clear, specific and brief summaries, backed up by references. My only interest in MBH98 was in regard to Tamino's discussion of Montford's book, based on your criticism of it which was a pure echo of McIntyre (and which McIntyre repeated recently at Keith Kloor's blog, without actually answering my questions). Now that we know that essentially everything Montford stated in that paragraph as a "fact" was false, I'm really not interested in further wiggling and self-justification from that crowd. Sorry. What limited trust I had left has been further played out.

Brandon Shollenberger covered

Brandon Shollenberger covered three points in his comment headed "1) This point is wrong". I can only comment on one part of his second point: the question of whether the inclusion of the Tiljander proxies "matters" to the interpretation of Mann08.

I believe that Brandon has stated that issue correctly.

If there are particular Tiljander/Mann08 issues that I might helpfully weigh in on, please state them. I will try to do so.

By the way, DeepClimate became the first prominent pro-AGW Consensus blogger to straightforwardly acknowledge that Mann08's use of the Tiljander proxies isn't justified, saying (in a comment in "Open Thread #4') --

Do I think the [Tiljander] proxies can be usefully calibrated to the instrumental record? No.