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 Smith, I am perfectly

Arthur Smith, I am perfectly fine with dropping this subject. Quite frankly, I dislike posting on blogs. I never meant to post as much as I have. However, I have to say something. Over at RealClimate you said (in part):

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.

This quote is obviously wrong in that Tamino's post didn't address the core criticisms of the hockey stick. As we have seen here, it is also wrong in that you don't even know the material being discussed. You had absolutely no basis for this statement. You chose to make a bold claim you couldn't support.

You can choose not to trust me if you wish. I have a standing offer to provide evidenciary support for anything and everything I have posted, so the only excuse you have is apathy. If you want to choose not to trust McIntyre, that is fine. If you don't want to take the time to figure out the issues, that is fine. Just stop acting like you know what you are talking about. I find it funny you say:

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.

My explanations of the issues covered in this topic have been the most clear and concise explanations I have seen. I can see nothing in my comments to suggest I don't understand what I am talking about, and the sheer level of factual information I have discussed would seem to suggest otherwise. I certainly cannot see anything to suggest I am some uninformed shill, mindlessly spouting off what other people have said. On the other hand, you clearly haven't investigated or understood a great number of things. In addition to the quote which started this exchange, I would point to:

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.

This comment had no basis in reality. You flat out made it up, and it directly contradicts what the authors said in their published work (which despite how you portray me, I both quoted and referenced).

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.

Again, this is completely untrue. The only way "the bulk of relevant data" is being removed is that the conclusions rely on a small portion of the data used. Only a fraction of the overall data is being removed. If removing only a fraction of the data being used removes "the bulk of relevant data," we have the obvious question, "What is the rest of the data doing there?" Regardless, everybody should expect conclusions derived from a multiproxy temperature reconstruction to hold true even if you remove one or two proxies.

This all started because you made a bold factual claim you couldn't support. You have since made several factual claims which are flagrantly untrue. That is unacceptable. Ignorance and apathy are perfectly acceptable responses to a question. Making things up is not. If you don't know or care about the hockey stick, fine. Just don't talk about it.

Brandon, all I know is what

Brandon, all I know is what I've read, much of which I have grave doubts about, and I agree that's limited. However, the PDF McIntyre pointed to from Mann in 2003, specifically stated:

... elimination of the critical datasets (1)-(3) ... from the
MBH98 network, ... account for the overwhelming majority of proxy data used during the
interval AD 1400-1500

which neither you, nor McIntyre, nor anybody else I've asked about this has responded with any answer on how they reconcile this with the Montford/McIntyre account that only 2 series were removed. Until somebody addresses that fundamental discrepancy between the paraphrases of what Mann said and what he actually said I see no reason to even think about this any further.

As to my claims about the hockey stick not being an illusion, as I said above, we seem to have different definitions of "the hockey stick". There seems to be no question that the period from 1500 to the present is perfectly adequately resolved in paleo-climate reconstructions, with or without tree rings (and Tiljander is irrelevant to that period). And that curve looks very much like a hockey-stick to me. There is no illusion about that. Agreed?

Regarding reconstructions to earlier times, either you trust tree rings, or you don't. If you don't, then you can't really say anything about temperatures at earlier times to within about 1 K or so, as far as I can tell from the latest discussion. We don't know if they went up around 900-1200, or down, or stayed about the same. But if you do trust tree rings, then there is a small Medieval Warm Period resolved, and some other ups and downs of that sort. Either way, the "trusted" part of the temperature reconstruction sure looks like a hockey stick to me. Calling it an illusion requires some real chutzpah.

Arthur Smith, I cannot

Arthur Smith, I cannot continue an exchange with you if you are going to continue the way you have thus far. This latest response of yours is pure garbage. You say:

neither you, nor McIntyre, nor anybody else I've asked about this has responded with any answer on how they reconcile this with the Montford/McIntyre account that only 2 series were removed.

This is completely untrue. You raised this issue here. I answered you here. My response even provided this link, as well as a quoted phrase which would let you find the exact text in which McIntyre discusses what you claim nobody had discussed. And to be sure there can be no doubt you read my response, you replied here and here. At that time you offered no question on the explanation, and you have offered none since. It is ridiculous to now act as though you have never been given an answer to your question. It is even more ridiculous to say:

As to my claims about the hockey stick not being an illusion, as I said above, we seem to have different definitions of "the hockey stick".

The controversy being discussed has been going on for something like a decade. While you are welcome to have some personal definition of "the hockey stick" based on whatever arbitrary lexicography you want, you have no right to expect anyone else to subscribe to your delusional ramblings. You certainly cannot dismiss people's criticisms because you willfully misread what they say.

Regarding reconstructions to earlier times, either you trust tree rings, or you don't.

Here you flat-out contradict what I have already said without even acknowledging what I have said. None of the papers I have discussed require trusting "tree rings." Instead, they require trusting a handful of tree rings as tracking global temperatures even though the majority do not show the same results. You massively reframe the argument here without any justification. You would have the question be, "Do you trust tree rings?" The real question would be something more like:

Do you trust a handful of tree rings (which an NAS panel said should be avoided in temperature reconstructions) accurately reflect global temperature trends while the larger number of tree rings do not?

So if you, or anyone else wants to discuss the details of criticisms of the hockey stick (many of which I have had to gloss over), I am more than willing to discuss them. However, I am not going to stay and post if all I am to do is spend all my time correcting willful delusions and flagrant misrepresentations.

Your link to McIntyre, and

Your link to McIntyre, and your previous comments, make no mention of the words "overwhelming majority of proxy data " which Mann used to describe this. Why did Mann use these words? That is the explanation I require. Otherwise what McIntyre says on the subject makes no sense, because he is basing it on what Mann said, but Mann used those specific words "overwhelming majority". I don't trust McIntyre's or anybody else's interpretation of Mann if they do not address the use of those specific words to describe the deletions that are in question.

Brandon, this is my blog, and you're accusing me of willful delusions and flagrant misrepresentations. Please moderate your own tone, and try to respond to the actual questions I raise, preferably with original thoughts of your own or links to sources *other than Steve McIntyre* (or your own regurgitations of McIntyre), who I have no reason to trust on this or any other matter.. I also do not want you to keep repeating your nonsense. If you continue to choose not to respond in a reasonable manner I am sorry but I will be forced to put you on moderation.

Depends on a limited amount

Depends on a limited amount of data could mean just sensitive to a few series.

That MBH98 only goes aback to 1400 or 1500 does take away a great deal of its hockeystickness. Hockey sticks are only primarily disputed with regard to comparing medieval warm period vs present. Mann's first paper had the problem of the little ice age disappearing. MBH99 I think goes back further

You have to remember.... That

You have to remember....

That MBH99 is only a NH recon. It is also true that the early MBH method tended to underestimate long term variability. Mann himself, among others, wrote papers comparing his methods with pseudoproxies looking for a better method. This is how he arrived at his current method. But yeah, of course this is how science progresses. Taking valid criticisms into account and investigating new methods/data.

Arthur wrote: "The

Arthur wrote: "The correlation of tree-ring data with temperature, however, is as far as I can tell extremely sound."

Is it? The point is heavily contested and at a level of detail which is simply frightening. However, were I to spend a bit of time rounding up the links and the evidence which is contra the tree ring to temp correlation would you accept that the two pillars upon which the hockey stick rests have collapsed?

[And, on a side note, being Canadian I have a pretty clear idea what a hockey stick looks like and how it is used: two foot shafts make hockey sticks pretty useless no matter how long the blade.]

If I can clarify things for

If I can clarify things for you, the answer is "yes", I do discuss Gaspe and NoAmer. The MM05 (EE) paper tested the sensitivity of MBH98 to Gaspe and NoAmer, and I give this part of the study quite a lot of airplay.

Really though, it would help if you read the book. You could buy a second-hand copy if the thought of paying me a pound of a royalty was too painful for you.

Arthur, You have penned some

Arthur, You have penned some eloquent comments recently, giving your view of the overall state of climate science. In your essays, you describe how the science has come to its consensus positions from the ground up. Among other reasons that we can be sure that the big ideas are mostly right, is that the widely-accepted building blocks are mostly good science, done right.

Here's a link to your synopsis on the marathon RealClimate "Tamino - HSI Book Review" thread, at #512.

Here's a link to a comment on the "The Chasm" thread at Collide-a-scape, at #45. You've also issued extensive challenges to Judy Curry on the basis for many of her remarks in the "Gavin" and "Curry" threads, regarding both arcane details and overall perspectives.

In that regard, it seems fair to inquire about the use of the Tiljander proxies by Mann08 (and Mann09 and Kaufman09). It's one of the little building blocks of a recent, heavily cited paper in a top-tier peer-reviewed journal.

We might conclude that Mann08's use of these data series was proper--even if a case to that effect has yet to be made.

Or, our conclusion might map to that of pro-AGW Consensus blogger DeepClimate, who recently wrote, "Do I think the proxies can be usefully calibrated to the instrumental record? No."

(Does DeepClimate's comment mean that the AGW edifice is crumbling? "Of course not.")

Ari Jokimatti started to look at this narrow issue, in his June 2010 post Tiljander. In the comments, it seemed that it was just too distasteful for him to contemplate agreeing with Steve McIntyre about anything. And so the matter has lain fallow for more than a month, as he moves on to other questions.

Could a similar dynamic be taking place here?

AMac, Based on MikeN's quoted


Based on MikeN's quoted head post at your blog, I can see a reason to exclude Lightsum and XRD from the CPS reconstruction. Both Darksum and Thickness satisfied the standard interpretation of varve proxies and passed Mann's screening procedure. He investigated the impact of including these proxies in the SI and explained why he included them. He might have made an error in his choice, but it had little impact on the results as reported in the paper.

Why don't you run an analysis which deletes the Lightsum and XRD (just delete them from the input file) and run it. The Matlab code is there and you can get a free Matlab interpreter from the intertubes. Run it and see what happens.

I also fail to see what your obsession with reconstructions which do not include dendro information is. Clearly the paleo community still sees dendro chronologies as providing important information. I strikes me that Mann was trying to anticipate attacks on his work that would come from McI and friends when he did his "no dendro" recons. The thing is that including dendro chronologies, which are considered to be the best source of accurate long climatic information (no matter what McI says, they are still good) gives a better idea of what has been going on than just geological proxies. Even the corrected Lohle recon (when properly calibrated to the instrumental record) still shows unusual 20th warming, and the corrected Lohele recon still has huge problems, much more than the Mann08 "no dendro" recons have (eg, no areal weighting and dating problems associated with geologic proxies)

Have fun, and let us know when you have an argument better than "I don't like the choice he made".

AMac - your expectations of

AMac - your expectations of my expenditure of time on this are unrealistic. I have a full time job, a big family, and many other commitments. It will probably take me at least a year of spare time to understand the problem sufficiently to draw much in the way of conclusions, given the mess that's been made out of it all. And like I said, if you push too much, I may just not care enough to spend the time at all. Let me tell you what I have done so far on this, and what I feel I still need to do, to make an assessment. If you don't like the way I'm doing it, you can go talk to somebody else. I suggest you talk to those who have already invested time in it - there have surely been many experienced outside scientists who have delved into the "hockey stick" - the NAS review, the various commissions and reviews of Climategate, etc.

What I have done so far:
* read many of AMac's comments on this (including Jokimatti, discussions with Gavin various places, etc.)
* downloaded Mann 2008 paper and some related papers
* read Mann 2008 twice - many things I still don't understand
* read a small number of background papers (including MBH 98, IPCC report discussions on paleo)
* downloaded Mann's supplementary info
* downloaded Mann's code and data

What I still need to do:
* understand Mann 2008 - that means:
* reading more background papers for the context of what they're doing
* reading and understanding the code they used for CPS and EIV calculations (I'm getting the feeling the EIV was more critical to Mann 2008, CPS was there just to provide some context for previous results)
* looking at the proxy data in some detail - graphing it, comparing it etc.
* Understand the Tiljander data in particular - that means:
* reading Tiljander's Boreas paper and any other documentation on it that's available
* looking at the data itself, again, graphing, comparing to other proxies
* understanding Mann's use of Tiljander; the degree of importance to his reconstructions
* possibly this may require running some version of Mann's code, or a simplified version, to compare
* As I understand it, the central issue is not the reconstructed temperature, but the degree of uncertainty in it - these are statistical issues that I am not at all personally familiar with, and again will require some background study to understand.

At this point, all I have on all the above are essentially anecdotes from, as far as I can tell, people who have not done anywhere near the work actually required to understand what Mann did. I want to understand it before I pass judgment. From the anecdotes, it sounds like there was a problem. But Mann does not admit one. If he admitted one, the question would be simple - both sides agree. Since two sides seem to disagree on the central questions, real expertise is demanded to pass judgment. I do not have that expertise. I am in the process of trying to acquire it, but it will take some time. Don't push me, please.

I just beat Amac up a bit and

I just beat Amac up a bit and then he spoonfed me.

I would read in this order
-McI's post about notability in M08 (treeless recons were touted, were a major part of what made the paper additive over previous)
-Mann08 (once, not a skim, but not a day long endeavor either)
-Tiljander Boreas paper (cool shiznet, not that great a study, but interesting mud)
-Amac's pictures of the data

Then I would just engage and ask questions.

> AMac - your expectations of

> AMac - your expectations of my expenditure of time on this are unrealistic.
Arthur, huh!? This is a hobby. You expressed your interest in the subject and opened the floor for discussion. I haven't -- and couldn't -- and don't particularly want to -- push you.

> I have a full time job, a big family, and many other commitments.
Understood. Me, too.

> I may just not care enough to spend the time at all.
You should do what you are motivated and interested to do. I would only expect particular results on a schedule if I was paying you. Alas, I am not in a position to do so, in any event.

As far as looking at the Tiljander data, the post The Tiljander Data Series: Data and Graphs may be useful.

Hmm, I just dug up the paper

Hmm, I just dug up the paper and printed it and found this little bit o' heaven:

When tree-ring data are eliminated from the proxy data
network, a skillful reconstruction is possible only back to A.D. 1500
by using the CPS approach but is possible considerably further back,
to A.D. 1000, by using the EIV approach.

Looks like tossing Tiljander didn't really change anything, since the whole damn argument seems to revolve around CPS, but removing Tiljander seems to leave the conclusions in the same place. No real difference.

"No real difference." See

"No real difference."

See Gavin's remarks in the RealClimate thread "The Montford Delusion" on this point. He refers to the SI of Mann09, which is a bit unusual, but there it is. You can get to the key points from McIntyre's post "The No Dendro Illusion."

AMac, Was that the thread


Was that the thread where he ran only the proxies back to 1000 (w/o any other proxies, those being the ones which ran back in years previous to, newer, than 1000? That seems like a bit of a strawman, since Mann, as quoted above, only claims skill with no dendro evidence back to 1500. Mann never made a claim about no dendro skill back to 1000 w/o dendro evidence in the CPS method. RegEM/TTLS/EIV is a different issue, but as far as I can see, McI has never addressed the RegEM/TTLS methodology. He is full of, excuse me, hot air.

Prove your claims or leave us alone. You do have your own blog afterall. Let us know when you have a finding rather than an opinion.

The issues raised in "AMac,

The issues raised in "AMac, was that the thread" were all considered under "Michael Mann's errors," in the sub-thread that begins with John Sully's comment "Except, it I understand the". My comment to that post "The "Tiljander" argument" is responsive to the more general issue of whether these questions matter.

Who is the "us" that I am to leave alone? Arthur Smith opened the post "Michael Mann's errors" to examine scientific matters arising with Mann08's use of the Tiljander proxies. All my comments have been on-topic and in accord with the facts as they have developed. It seems to me that readers who are interested in engaging in this topic should do so, while those who are not, should not.