The Main Hindrance to Dialogue (and Detente)
Today I received an email from Gavin Schmidt, who said he was having trouble posting a comment. (Darn this new system which I’m alternately loving and hating.)
Rather than plop Gavin’s comment into the thread, I believe what he says warrants highlighting in a stand-alone post. In particular, I hope readers take up Gavin’s main issue (reflected in the headline I chose for this post), which relates to why he thinks scientists don’t engage more in blog comment threads. Be advised: I’m not interested in readers rehashing the “Tiljander” argument in this thread. Please be polite and stay on topic.
From Gavin Schmidt:
One of the pathologies of blog comment threads is the appearance of continual demands that mainstream scientists demand retractions of published work or condemnations of specific scientists for supposed errors or other sins. Most often the issue in question has been discussed dozens of times previously and is usually based either on an irrelevancy, or was acknowledged clearly in the original or subsequent paper or is based on some misperception of the science. [See Mann et al (2008) paper.]
Nonetheless, these demands are being used as some kind of litmus test for the kind of scientist one can respect and they clearly resonate with people who don’t know anything about the subject. However, for those that do, it serves only to signal that there is no reason to engage since the first explanation should have dealt with the issue. How many times do you need to correct someone’s misperception of a point of science? If they were sincerely looking for truth, the answer would be once. If instead they are trying to find issues with which they can bash scientists for another reason, the answer is apparently infinite. No scientists have time for that, and this kind of continual low-level insinuation is simply too tiresome to deal with.
I think the correct answer is: In principle, exactly once. But it's important to understand this answer can only apply when all of the following are true:
a) someone actually has a misperception,
b) you correctly identify what someone is perceiving and can pinpoint what precisely is wrong with their view,
c) your correction is responsive to the actual misperception,
d) your answer is clear and convincing and does not contain any holes,
e) readers can tell you actually addressed a misperception harbored by someone, somewhere, rather than merely rebutting a watered down point that might appear similar to you,
f) your answer doesn't send people down blind allies by suggesting that the question was answered in a blog post addressing another subject. (This red herring tactic will often make people stop reading, preventing them from ever noticing the convincing arguments that might be contained in later portions of the post.)
g) the answer is provided in a forum read by people actually who harbor the misperception you address
h) your responses to their arguments does not appear to contain slams insinuating that people asking you questions are not seeking the truth.
If your correction fails on any of these points you will almost certainly need to repeat your attempt to correct their misperception. You will feel like you keep repeating the same thing over and over.
When this happens to you, it might be worthwhile if you paused to identify whether what you are writing is addressing notions people actually harbor or answers questions they really have.
One way to assure yourself you have addressed their notions would be to actually quote what they said, link to articles where you think the misperception appears and encourage a two way discussion. My impression is that this is not the standard practice at your blog.
I should also note that in practice, the population of the world is large. You will likely find that even if you clarified one person's misperception a different person sharing the same misperception may come along. In this case, you may have to repeat your answer; of course, you may be able to convince the second by linking back to the answer you gave the first. However, if, owing to failure to listen, you are mistaken about the precise nature of the 2nd persons misperception, you will find complaining that you have already answered their question and sending them to a post that they think discusses a different topic will only cause the second person. This is a violation of point "f" above and you will find that you must repeat what you consider to be the same arguments over and over and over.
In any event, it is a fact that in practice, you will have to repeat even the best sounds arguments more than once because the public consists of many people. The number you need to address something you consider to be a misperception is not infinite, but it is rather large.
Gavin, many thanks for your comment. You say:
Could you point out where the problems with the Mann et al (2008) paper are "based either on an irrelevancy, or was acknowledged clearly in the original or subsequent paper or is based on some misperception of the science." I don't find, for example, that the use in that paper of the bristlecones, or the use of upside-down Tiljander proxies, fit any of those criteria.
Thanks,
w.
Gavin, I agree with your comments in the context of the known knowns, such as the recent "skepticism" regarding the Stefan Boltzmann Law and black body radiation (you and I recently shared the "spotlight" on this one at http://www.canadafreepress.com/index.php/article/… I'm with you on that one). However, with regards to Mann et al. (1998), this is clearly in the frontiers of knowledge category, well within the range of scientific debate. To lump critics of the Stefan-Boltzmann Law (quackology, basically) with serious criticism of Mann et al. (2008) is counter productive. Engaging in dialogue on the frontiers of knowledge category, basically on the edge of ignorance, is essential for scientific progress. Pretending that Mann et al. (2008) is established on the same level as say the Stefan-Boltzmann Law just won't pass muster. Apart from the challenges by McIntyre et al., see also this interesting post over at Der Klimazweibel by Bo Christiansen http://klimazwiebel.blogspot.com/2010/05/guest-po…
Note, the chief bunny is also commenting on this issue at Rabbett Run http://rabett.blogspot.com/2010/06/progress-is-el…
Willis apparently you missed Keith's bit about Tijander…
Just so that the context is clear for the above comment, the 'tiljander' issue that commenter 'Amac' has brought up on dozens of blogs without paying the least heed to the responses he has got from many people, is answered as follows:
Given the methodology used in that particular paper (Mann et al, 2008) (weighting based on a local calibration to temperature in the modern period), the 'tiljander' proxies can only be used one way. If there is a contamination in the modern period by non-climatic influences (which the originating authors suggested there might be), then they just can't be used. This issue was clearly acknowledged in the M08 paper and both of these possibilities (with and without 'tiljander') were shown (it made almost no difference to the final reconstruction).
Supp. Fig. S8a
(Note that figure also shows the difference dropping all the tree-ring data makes, and what happens when the neither the tree ring data nor the Tiljander proxies are not used).
Thus we have the authors of a synthesis paper taking into account caveats mentioned by the data originators, testing the robustness of their reconstruction to the inclusion or not of these proxies and even going further to explore how different classes of proxies interact. Not only that, but all of the code and data are online and so any of the people who are still not satisfied can simply run the code themselves to see what difference any of their points make. This is not to state that M08 is the last word on anything, but this particular criticism just does not stand up to scrutiny.
Now, the above content has been repeated on RC, Deltoid, Stoat and perhaps other places, yet the same commenter brings it up here again. For whatever reason, the "scientist's" answer has not been convincing, was not clear enough, or has just not been read.
However, since that answer isn't going to change, there is a limit to how many times it will be repeated.
Thus we have an impasse. Further repetition of the 'talking point' will simply drive away frustrated scientists, so if that is what is wanted, this tactic works well. Harassing the few scientists who bother with these blogs with the same question wherever they comment will have the same effect.
If on the other hand the aim is to engage people constructively, people have to do something else. For instance, they can either agree to disagree and discuss some other topic on which resolution might be possible, or (wonder of wonders) actually try and understand why the scientists make the point they do (and no, the answer is not because they are a paid-up member of some conspiracy).
The fact is, there *does* appear to be a desire on the part of some to really engage scientists directly for, presumably, the insight and context that only they can provide. But the use of litmus tests like these are completely antithetical to that desire.
So, people need to choose one way or another. But they can't claim that they sincerely want to engage at the same time they continue to try and play 'gotcha'. Everyone is just too busy for that kind of thing.
This is probably the main issue in communicating between different “camps”. Michael Tobis made a very similar argument at CA ( http://climateaudit.org/2010/06/04/losing-glacier… )
“It comes down to a fundamental question. Are you interested in improving the world’s and your own understanding the climate system as a physical system, a problem which in principle really ought to be at least partially resolvable? Or are you interested in demeaning and undermining the people who have made the most effort toward doing so?”
And Lucia’s reply hints to the problem being that people have very different perceptions of who have serius questions vs those who just want to derail. Undoubtedly both kinds of people exist (and of course not in such a black and white way, but rather in a continuum of dark-light grey).
So how is a scientist supposed to evaluate if somebody is sincerly interested in improving their understanding of the climate system, vs interested in scoring points against the scientific consensus?
(cont'd)
In engaging with people, I usually start off with giving them the benefit of the doubt (unless it's overly conspiratorial). After a while I start making up my mind whether a person is worth engaging further or not, to avoid falling into a bottomless pit of lost effort. I don't always succeed in avoiding this trap, and likewise I may have 'given up' on people who actually are sincere, but merely strongheaded and misguided (which is probaby the shade of grey that is most common, and hardest to place, since they would rightly be offended if it is insinuated that they're not sincere or ideologically motivated, yet engaging them still has a very high chance of of not leading to any learning of either 'side'.
Bart, I think it was Judith Curry who recently advised (I think at MT's site or at CA) that it was necessary to engage with the people who you felt were serious and not with those are just looking to score points or derail a conversation. I think I reached that conclusion independently not too long ago but she helped reaffirm it for me.
Because I found myself repeatedly falling into that bottomless pit with the most vocal commenters on all sides of the climate debate.
Gavin, thanks for your reply. There is an oddity about the Mann2008 paper. It uses both the bristlecones and the upside down Tiljander proxies. As you point out, if you take out either one of these, you still get the same result.
But that is not a sufficient test. Neither set of proxies should be used. And if you take both of them out, you don't get the hockeystick.
See here for a discussion of the issues, and the comment here for the sources of the hockeystick. Out of all of the proxies, the majority do not show any hockeystick shape at all. It is entirely contained in the bristlecones, the Tiljander proxy, and (to a lesser extent) Briffa's "adjusted" Tornetrask proxies. All three of these are known to have problems. In addition, the Tornetrask proxies are unarchived. Problems with these proxies have been widely discussed in the literature, yet Mann2008 uses all of them.
You seem to be impressed that removing one of the three proxy groups known to have problems doesn't make much difference. All that shows is the weakness of the test. Take them all out, and it makes a huge difference.
Although these are a minority of the proxies, the others average out, and as a result, we get a hockeystick.
w.
PS – It is curious that you neglected to mention the bristlecones, after I specifically asked about them. Your comments on that, on the Tornetrask issue, and on the use of unarchived datasets would be welcome.
Gavin —
I never dreamed that I or anyone else would be talking about the Lake Korttajarvi proxies (I avoided the "T" word), eight months after I first heard of the subject while browsing Roger Pielke Jr.'s blog (Comment #35). A lot of technical things are complex, and require expert knowledge and context. Much of climate science–a very broad and complicated field–is that way.
The use by Mann08 of these four proxies isn't. To the contrary, it's an issue that is accessible to any scientifically-literate lay reader. I thought then that it would be "put to bed" in a matter of days or weeks.
Mann08 screened and used various records (proxies) for temperature in order to construct a global temperature anomaly stretching from 200 AD to 1850. To qualify for either of the authors' methods (CPS or RegEM), each proxy had to be calibratable to the instrumental temperature record, 1850-1995.
The four records derived from the Lake Korttajarvi lakebed sediments are not. In their 2003 description in the journal Boreas, the authors explained why: the local effects of farming and roadbuilding contaminated the record, 1720-on.
Mann08's authors considered this caution, decided they could show that it didn't apply, and proceeded to incorporate the four proxies in their analyses. This is explained in the paper's Supplemental Information.
This was an honest mistake–but still a mistake. Bad data went into the analyses.
As I said, interested lay readers who are scientifically literate can follow this reasoning for themselves. I've linked all the information known to me — pro and con — in two posts, primary literature and blog posts.
Of course there are subtle, complex arguments to be made, as you have done at RealClimate, and as you do in more detail in the earlier comment on this thread, beginning "Just so that the context is clear for the above comment".
But there is an earlier, simpler, easier yes-or-no question that is obvious.
"Are the Tiljander proxies calibratable to the instrumental temperature record, 1850-1995?"
That question–originally asked by Steve McIntyre–has yet to be answered. By Prof. Mann, by his co-authors, by RealClimate co-bloggers, by William Connolley… by any climate scientist.
This issue is very relevant to the points made by Lucia, above, in her comment above that begins, "I think the correct answer is: In principle, exactly once."
In closing: The basic issue was simple but unaddressed in September 2008 (when Mann08 was published), and in October 2009 (when I first learned of it). It remains simple, today.
Thank you, Dr. Schmidt, for taking the time to set forth your views on the subject. Your frustration is evident, but perhaps some forward movement can come from a resolution that focuses on the scientific issues in question.
Amac/Willis:
As I said, I'm really not interested in getting lost in this thicket. I'm sorry if that frustrates you. Can we set your technical questions aside and address the larger issue that Gavin raises?
Perhaps you can't go there until the matters you raise in your own comments are addressed to your satisfaction. So be it. Gavin believes they have been addressed. So where do we go from there? What's the meeting ground where other dialogue can take place?
So much for not rehashing Tiljander.
Figure S8 takes out 7 proxies — including all four Tiljander proxies — and the current temps still exceed the previous maximum.
Figure S7 takes out *all* of the dendro proxies; the previous maximum is now higher (and occurs prior to 500AD a period where 'reconstructions are not skillful") — but the current temps *still* exceed the previous maximum.
As Mann et al note:
"Fig. S7. …..The point of this comparison is simply that the anomalousness of recent warming in the long-term context of the reconstructions does not depend on whether or not tree-ring data have been used.]"
Doesn't that matter more than how much the 'hockey stick' approximates a real hockey stick? It could look more like a sea serpent with its head way out of the water — the key message would be the same: It's likely warmer now than any time in the last 2000 years.
Stephen,
Can't you see that I'm trying to avoid that without directly editing anybody? I understand this is like a reflux reaction for many of you, and I'm well aware that by calling this offlimits I may be stifling debate.
So I'm asking you all: can we get around this by agreeing to disagree and move on to another issue of contention?
Keith,
As far as I can see, the difficulty is that Gavin believes he has responded to the ‘perpetual question”. However, it appears that it does not address the perpetual question Willis and Amac are asking. This perpetual question related to the content in the 2nd sentence in Willis’s comment:
Basically, Gavin is explaining, and I believe has re-explained the point in the first sentence many times. But few are questioning that point– AMac and Willis don’t. They are making the second point, and their questions are related to the second point.
Now, I have no idea if the claim Willis makes in his second sentence is true. But I can tell the claim in the 2nd sentences is not the same claim as in the first sentence. I’m pretty sure Gavin’s answer related to the first question. This means that AMac and Willis may not mispercieving anything, or if they do, Gavin has incorrectly identified what they misperceive. Certainly, with regard to what AMac and Willis claim or ask, Gavin’s response has holes– because he doesn’t address their actual question or claim.
I realize that Gavin believes he has addressed Willis and Amac’s issue. But seems to me he has not.
If Gavin does not return to address the question of what happens if you take both flawed proxies out, (either telling Willis or Amac pointing to where a paper where this specific issues has been addressed or admitting that it has not been addressed and that Willis and Amac may well be correct), then this issue will be raised over and over again at blogs.
As far as I can see, the difficulty with Gavin’s response to the perpetual question is that it’s possible he has never addressed it. But if my impression is wrong, it might be wise for him to explicitly state what happens if both flawed proxies are removed, and to point to the paper that discusses this.
"reflux reaction"
That's a little too evocative for my taste, Keith. Stick with "reflex." 🙂
Amac:
"The four records derived from the Lake Korttajarvi lakebed sediments are not. In their 2003 description in the journal Boreas, the authors explained why: the local effects of farming and roadbuilding contaminated the record, 1720-on.
"Mann08's authors considered this caution, decided they could show that it didn't apply, and proceeded to incorporate the four proxies in their analyses. This is explained in the paper's Supplemental Information.
"This was an honest mistake–but still a mistake. Bad data went into the analyses."
This evinces a really key misunderstanding. What the people who collected the proxy data do or don't think about how it ought to be used is in and of itself meaningless. What somebody else did with it might be wrong, although that would have to be proven via analysis, but it's not in any sense a "mistake" simply because the original authors seem to be saying that.
Steve, I understand that you feel compelled to respond to Amac, but this is precisely the sort of back and forth I wanted to avoid. It can just go on ad naseum.
But I'm willing to consider that Lucia may be on to something with all this mutual misperception stuff and I'm hoping that maybe Gavin can take that up and we can move on from there.
Steve Bloom —
Reasonable response. I think that means that your answer to
"Are the Tiljander proxies calibratable to the instrumental temperature record, 1850-1995?" is "Yes."
But this is Keith's site, he's said he doesn't want discussion of the issue, so I'll stop here.
Lucia,
The question you ascribe to me is certainly a good one, and one I find relevant and important. But I've tried to start at the beginning. Thus, instead, for now, I focus on the very simple Yes/No question, "Are the Tiljander proxies calibratable to the instrumental temperature record, 1850-1995?"
Keith,
> Can we set your technical questions aside and address the larger issue that Gavin raises?
It's your blog, so the answer is "Yes." (Mea culpa, my responses just now to Steve Bloom and Lucia were cheats (but short, anyway)).
That said, your request is on its face unreasonable. Your correspondent Gavin has framed his issue in terms of the technical issue of Tiljander. Aside from Tiljander, he's made a series of statements about my posts and me, and cited one of my recent posts here as an example of a "pathology". That comment was, yes, about Tiljander.
You could have written back to Gavin, "How about if you make your point without making particular accusations surrounding a particular technical issue, which are sure to be seen as straw-man arguments and ad hominem attacks? I don't want this post to end up getting lost in the Tiljander thicket, so how about it?"
Then we could talk about the general, and I wouldn't even know that the bloggers at RealClimate even read my comments at a few websites, much less elevate them and their author to pathologies.
But you're the host here, I'll honor your request. Let's hope that the thread goes in the direction that Judith Curry would hope, in terms of finding areas of agreement, increasing respectful substantive communication, and decreasing tribalism.
Lucia's points strike me as steps along that pathway.
Apart from the nuanced issues related to proxies (personally, my eyes glaze over at this stuff, even though i know it is of some importance), this exchange does illustrate some general points re communication. Its easier to answer your own question than somebody else's (and occasionally its just difficult to figure out exactly what the question is). So people continue to answer the question that wasn't asked, and then get perturbed when people keep asking the same question that never gets answered.
If I know anything at all about dendro, its that the whole issue of tree ring proxies is very much open for debate. The onus is really on the people or wrote the papers (or by proxy their blogospheric defenders) to address the questions. The questions being asked are technical ones, and Steve Mc's activities have spawned a real cottage industry of expertise in dendro proxies. The CA crowd and others that have been spawned from CA know a heck of a lot more than I do about dendro (even tho I am a "card carrying" climate researcher.) So these are not stupid questions from flat earth types, they are serious questions from educated people that have dug into the subject (lets face it, dendro isn't rocket science). If a scientist can't convince such a group of people, then I'm not sure who they can expect to convince, other than by "appeal to authority" arguments. The blogosphere is a brave new world that is enabling nontraditional groups to develop expertise and challenge the "elite" science conducted by academic and government researchers. This is good for science, and its good for policy to have a populace that is educated in these matters. Lets figure out how to put this energy and expertise to productive use, rather than dismissing it.
Keith, I hope it is ok to talk here about the social psychology of dendrochronology (I've avoided the technical issues).
Judith, that seems fair enough to me. I suppose I'm just dubious that both sides can navigate around the landscape of mutual hostility and suspicion that this debate has come to inhabit.
And that is why I have been ardently trying to plow new ground (with a huge assist from you) for people to step on and have exchanges in good faith.
So I'm with you a 100 percent on trying to "figure out how to put this energy and expertise" of the blogosphere to productive use." I just think we need to see if we can establish some common ground before tackling these major bones of contention.
All that said, Amac is right to note that "Gavin has framed his issue in terms of the technical issue of Tiljander."
Amac also is right to say: "You could have written back to Gavin, 'How about if you make your point without making particular accusations surrounding a particular technical issue, which are sure to be seen as straw-man arguments and ad hominem attacks? I don't want this post to end up getting lost in the Tiljander thicket, so how about it?'"
But if Gavin didn't do that, he would have had to provide another example to make his point, so damned if you do, damned if you don't. He just happened to use an example that is sure to stir passions on all sides and it's those passions that I fear will overwhelm rational debate. I guess that's another way of me saying we have to bring the emotional level down a few notches before going head to head on this.
That's why I'm puzzled on how to get around this little predicament and am thinking that Lucia has offered a pathway. What do you think?
Keith, You are surely right that new approaches are needed. So, see where this goes, with all parties forgoing mention of the T*******r p*****s. One way of phrasing this hope: As the general issues are addressed and common ground is discovered, specific issues will come to be seen in a new, more tractable light.
By the way, I recall that Steve McIntyre has claimed that he proposed an "armistice" with James Annan, to lead to a joint publication laying out their areas of agreement and disagreement. That didn't gain traction, then. Maybe it's time for something like that?
Judith, just to clarify: yes, it is totally fine to discuss "the social psychology of dendrochronology" here. Additionally, courtesy of Lucia, here is what I wondered what might serve as a useful entry for Gavin to address in a one-stop fashion the outstanding issues that Amac/Will et al can't get past. From Lucia upthread:
"If Gavin does not return to address the question of what happens if you take both flawed proxies out, (either telling Willis or Amac pointing to where a paper where this specific issues has been addressed or admitting that it has not been addressed and that Willis and Amac may well be correct), then this issue will be raised over and over again at blogs."
"As far as I can see, the difficulty with Gavin's response to the perpetual question is that it's possible he has never addressed it. But if my impression is wrong, it might be wise for him to explicitly state what happens if both flawed proxies are removed, and to point to the paper that discusses this."
What do you think of this request by Lucia? Not having followed these wars in detail, is it a repetitive request or a reasonable query?
Of course, ideally, Gavin could weigh in with what he thinks of it, too.
Ok. I thought both you and willis were making the same point — which was not being addressed. So, instead it appears you each ask different questions, neither of which is addressed by Gavin's narrative. Am I mistaken?
Lucia,
Answering my question would likely narrow and simplify the answer to Willis' question: If calibration is not possible, it seems to me that they would therefore need to be removed from the
RegEMEIV and CPS reconstruction procedures.Answering Willis' question would help resolve a deeper issue with the paper, allowing a much clearer interpretation of the Fig. S8a that Gavin links to, supra. That would be very helpful, though it would not imply an answer to the calibratability question.
Keith,
A lot of the argument is based on a sense of perspectives on both sides. Some feel that some things are urgent, others not so important (and the 2×2 combinations in between).
Not to get into the "thicket" or "weeds", but the "quality of data" disregard is an <bold>extreme</bold> put off by people that work in the modern controlled manufacturing and quality managed environments (hi-tech, medical, etc), and this "research scientist" versus "application engineer" divide is huge. Simply saying something is cost prohibitive to put systems in place causes "pie eyes". I suppose I will step away from the BP current events.
ISO standards and quality management systems have been around longer than computers, and yes, they are a pain in the butt to manage, but they give more creditability to organizations that use them. If you use these systems, you willing open yourself to the "audit" of an outside person or organization. "Continual Improvement" is the mantra, nobody in their right mind likes it, it is your trial for certification.
Anyhow, until this rift between the "science" and the "engineering" is settled, their is always going to be the "sniper-shots" and the concealment of systematic "flaws" (Manufacturing term is much stronger in language).
Just an opinion, but I do like the attempt to shake out the politics. Good luck!
Keith says
" I suppose I'm just dubious that both sides can navigate around the landscape of mutual hostility and suspicion that this debate has come to inhabit. "
I would point out this has been done. For an example of how this should be accomplished, check out the Science of Doom website. My impression is that Science of Doom is both highly scientific and is a strong believer in AGW. He seems to keep a firm hand to keep the thread centered on target and does the work to actually mutual understanding of the scientific principles in play. An effort is made to actually explore and answer the questions that are honestly ask on the blog.
Yes, some questions tend to get ask over and over (though not so much by the most common posters) and he deals with this by gently referring folks to threads where the questions are actually dealt with. I also note that this mean threads that really deal with the subject matter, not a quick brush off to a thread that contains reframed questions that the site owner feels are more "politically correct".
I tend to have "lukewarmer" sympathies, but I would make the point that I "trust" Science of Doom even though we have differing viewpoints. He presents the data in a scientific fashion and I have confidence that everything is on the table and no inconvenient data is being swept under the rug for political purposes.
If you really want to convince me of AGW, dump the RealClimate methods and personalities and embrace the more scientific methods and arguments in a fashion much like Science of Doom.
As expected, the pathological dynamic worked it's magic again. I say pathological advisedly because in both of the responses Amac and Willis both simply regurgitated points they've made before without bothering to read what I said, and without clicking on the link (where, if they had cared to look, a reconstruction without both tree rings *and* the Tiljander proxies is shown – and yes, it looks similar to the others). Secondly, the 'issue' is boiled down to a demand that I answer some 'simple' question and denounce the original paper as 'a bad mistake'.
But here is where the problem lies. It is *never* a mistake to ask questions. What would the reconstruction look like with those proxies? What would it look like without them? Asking questions in a paper is not 'a mistake'. (Mistakes are when people confuse the standard error on an estimate of a mean with the expected spread (cf. Douglass et al), or when someone uses the raw Mg/Ca ratios in a temperature reconstruction instead of the actual temperatures (cf. Loehle) or when invents their own version of what the IPCC projections were (cf. Monckton). )
Asking questions of data is what scientists do. A demand that I denounce the asking of a question is not 'skepticism' or 'constructive criticism', it is an attack on science itself. Of course other questions could be asked – and other scientists are certainly doing so – and they yet may end up improving our understanding of the past climate. But trying to reduce the whole issue of paleo-climate reconstructions to a simple yes or no question about a single set of proxies is disingenuous. Why? Because the answer is either yes or no; if yes, they can be useful in the Mann et al method, and if not, they can't – but both possibilities were *already* presented in the paper. For any actual practical purpose the question posed is moot. It simply doesn't matter. If you don't like those proxies, use the reconstruction without them (and without the tree rings as well if you want), and if you do like them, then use the reconstruction that includes them. The differences are minimal. As stated above, the code and data are all available, so just go ahead and knock yourself out.
This is actually a very typical dynamic. There is a focus on a very specific point – that does in fact have a very easy resolution – but one which has no actual import. Discussing something that doesn't matter is by definition a waste of time, and so scientists will disengage. Indeed, it is precisely the role of scientists to distinguish between questions that do or do not matter – and pursue the former at the expense of the latter. Continually focusing on issues that do not matter is a classic diversionary tactic in any debate and this is evident in almost all of these blog conversations.
At this point, someone will say that my declaration that something 'doesn't matter' is just my opinion, and that in their opinion it does! In which case they are fully at liberty to discuss it – but just don't expect any input from the scientists.
Keith, please allow me a short excursion through the Mann 2008 sensitivity analyses, because they have great implications for the subject of this thread. I will have to split it into two parts because your blog won't allow long posts, so this is part one. Gavin, you say:
Sadly, this is not true. Contrary to Gavin's claim, Figure 8a does not show the situation when neither the tree-ring nor the Tiljander proxies are used. The caption for Figure S8a says:
The "seven potentially problematic series" are the four Tiljander series, along with three others. Here is the entirety of what the Mann2008 SOI says about the sensitivity analyses they conducted:
Note that, contrary to Gavin's claim, they first looked at the "full global proxy network" both with and without tree rings (Fig. S7). Then they separately looked at the "full global proxy network" with and without the Tiljander and other problematic proxies (Fig. S8). In no case did they look at the situation without both groups, much less without the equally problematic Tornetrask proxies.
Post, Part 2:
So that is the situation regarding Tiljander. Now, let me return to how this relates the subject of the thread. This discussion of Tiljander, and Gavin's willingness to answer, shows the great value of climate scientists engaging those of us outside of mainstream climate science who also study these issues. It allows everyone to see whose claims are supported by the data. In this case, we can all see that, despite his fervent belief that this issue has been decided and settled, Gavin's claims are wrong … which is how science progresses.
I applaud Gavin for his willingness to discuss this question here, and I encourage other climate scientists to do the same. Yes, the blogs are a rough-and-tumble kind of place … but the mainstream scientists are losing the battle for the public (and hence the political) support for their ideas. I believe that in large part this is because most of the mainstream scientists are unwilling to publicly discuss and debate the issues. Various reasons are given for this unwillingness, some of which are excellent reasons. Others of the reasons, such as Gavin's claim that the issues have already been settled, may or may not be valid.
But the net result is that we all lose when mainstream climate scientists are unwilling to publicly defend their results. The public loses because they don't get to hear the mainstream views. The skeptics lose because whatever erroneous claims we might have don't get corrected.
But the mainstream climate scientists lose triple. First, erroneous skeptical views go unchallenged. Second, erroneous mainstream views (such as the idea that Mann2008 looked at the effect of removing both bristlecones and Tiljander) do not get corrected. But the greatest loss is that the public looks at the blogs and says "Well, if the mainstream scientists won't show up to defend their views, maybe they're not really sure about them, maybe there's something they don't want us to find out."
I don't think that's true … but it is certainly the impression that the public is left with.
So I am grateful to both Keith and Gavin for providing both a theoretical subject and an practical example to discuss these issues.
My regards to all,
w.
Dr. Gavin, thanx for your contribution. We are scared. If you and the rest of the "team" is right with your dire predictions, then humanity may have commited a mass suicide, just as we were starting to see great things from technology.
This is the fight: Intellectually, I understand and respect your work. Emotionally, you have to be wrong.
There is your customer, how you square that circle, I am sorry, I can offer you no help.
Ah but Willis, it is a double edged sword that you propose. I can't count how many times I have read something like, "and wats with the guy Scmidt, using my tax dollars while at work to post things on his blog?" They can't win Willis. You can keep on hammering at this Mann08 thing, or whatever the pleasure of the day, all you want. You either accept Gavin's/whichever scientists answer, or just state at his blog, "sorry mate, I think your wrong and here's why". Then you gotta move on……. or publish.
Ah but Dr. Bart, even after hitting my thumb with my hammer for the fortieth time, I still learn something new, it may be as trivial as a new way of spouting my cuss words, but still….
:)~
Actually, Keith, I was addressing a misperception rather than a science issue. Oddly, amac misunderstood me. I'll try again since I think it's pertinent, but feel free to not let it through if you disagree.
amac, I think Keith wasn't clear on the point I was trying to make.
I wasn't addressing the question of what the appropriate use of those proxies might be (I have no idea and won't spend time on it since IMHO late Holocene paleoclimate is mostly interesting for historical reasons rather than scientific ones), but rather whether a mistake has been made if another scientist subsequently decides to put the proxies to a use the original authors deem inappropriate. In short, no it doesn't. Such a use may or may not actually be a mistake, but that would have to be demonstrated by something more than an opinion.
Judy, people in dendrochronology seem to think physical intuition is important. I suspect that's true in your field(s) as well. Lacking it, and it seems to me it's awfully hard to acquire outside of the grad school/postdoc grind, I would say the expertise of McI and his cohort would have to be deemed incomplete. Since they came to the science with a political agenda, this lack makes it very difficult to convince them of anything and leads to the syndrome Gavin describes.
W. You're joking right? The public is riveted to your debate over tree rings? Come on, that's ….well not very likely now is it?
This 'debate' looks like an effort to some how find a way that humans are not responsible for climate change. Is some of the data and analysis flawed? Maybe but so what? There is clear evidence CC is underway — the Arctic is melting etc — so what are we going to do about it?
Steve, this is the kind of poisonous speculation that I want to avoid on this blog: "since they came to the science with a political agenda…"
If you want to rebut Judith (or anyone you disagree with), do it with without speculating vaguely and broadly about motive. That is poisonous to constructive debate.
As the subject of Gavin's comment that was the impetus for this post, I will respond to his comment upthread that begins
1. In my opinion, Gavin's comment makes many claims that merit a technical rebuttal. His comment also includes a substantial number of straw-man arguments, non sequitors, and gratuitous insults. In the spirit of Keith's request, I'll forgo addressing these here.
2. One approach to a complex and contentious problem is to look for component issues that might be resolvable. Ideally, such a component can be expressed as a plainly-worded and easy-to-understand question that (if answerable) has the promise of simplifying the overall problem. Sometimes this is not possible. Instead, a series of If/Then premises have to be considered in sequence, or simultaneously.
While this approach is successful for individuals tackling advanced suduko, it isn't preferred. A better way to solve a hard suduko is to begin by identifying the easier parts of the puzzle, and filling them in. Keeping things holistic and complex is a strategy that is particularly ill-suited to occasions where participants bring different skill sets to the table. And where people have strong preferences as to the outcome. And where trust is low and emotions run high. All these caveats apply to Mann08.
3. I've distilled my concerns about the use of the Tiljander proxies in Mann08 to one question.
"Are the Tiljander proxies calibratable to the instrumental temperature record, 1850-1995?"
To date, to my knowledge, this question has never been directly answered by an author of Mann08, or by a working climate scientist, or by a prominent AGW Consensus advocate.
In his comment supra, Gavin says
His grammar is elliptical, but it appears that Gavin's "very specific point" is the "Calibratable? question" that I repeated just now.
If so, Gavin's following words are helpful in moving towards a resolution of the controversy surrounding Mann08.
3a. "that does in fact have a very easy resolution" would indicate that Gavin believes that the "Calibratable? question" is easily resolved. Point of agreement.
3b. "but one which has no actual import. Discussing something that doesn't matter is by definition a waste of time" would indicate that Gavin believes that the "Calibratable? question" is trivial. In contrast, I think that Mann08's methods absolutely demand the calibratability of all of the proxy series that are used in producing the paper's key results: the CPS and the EIV paleotemperature reconstructions. Point of disagreement clarified; the discussion is advanced.
4. Question to Gavin: Is my interpretation in #3 a fair and accurate representation of the point you intended to make?
Steve, I accept that you don't find late Holocene paleoclimate to be an interesting scientific subject. The authors of Mann08, and I, obviously feel differently. There's a discussion to be had about the pros and cons of people's enhanced ability to form virtual communities around the subjects that most interest them; I'll forgo that for now.
It is possible that Mann08's authors intentionally used the Lake Korttajarvi varve proxies in a way that the original authors deemed inappropriate.
If so, it would have been good practice for the authors to have made this point explicit in the Methods, where they spend considerable time discussing these proxies.
And effective peer-review would have led to PNAS' editors insisting that the authors address this issue (if it is an issue).
However, to my knowledge, the authors of Mann08 have not made this claim: in the paper, or the SI, or their 2009 Reply to McIntyre and McKitrick, or elsewhere.
I explored one aspect of "inappropriate" use of a proxy in a blog post about a hypothetical "Jarvykortta River" data series, here.
This thread is an instructive example of how the two sides of the debate are talking past each other. Contra W, Gavin is correct that the link he provides does show the reconstruction without Tijlander and tree rings. It is the reconstruction labeled "NH CPS minus 7 w/o tree rings". However, he is being misleading when he says: "This issue was clearly acknowledged in the M08 paper and both of these possibilities (with and without 'tiljander') were shown (it made almost no difference to the final reconstruction)."
On the contrary, this graph (showing the elimination of both) was published by Mann as a supplement over a year after the original paper. And it was done in a way that admitted no error in the original. It is also not true to say that this makes no difference to the reconstruction – note the elevated MCA. If this graph had been published with the original paper, it would have muted the visual impact.
Gavin is again correct than Mann did discuss potential problems with Tijlander in the original paper. But that does not mean that the use was still not a mistake. Above Steve Bloom errs in saying: "This evinces a really key misunderstanding. What the people who collected the proxy data do or don't think about how it ought to be used is in and of itself meaningless." This would be bad scientific / statistical practice. One of the core principles in statistical analysis is that you test an ex ante hypothesis, otherwise you are just data mining and any correlations you get are likely to get are spurious. If Mann believed that the correct correlation between the sediment data and temperature was different to Tijlander's interpretation, it was incumbent on him to discuss and explain why. I see no evidence that he did so. As a result, the sediment series should have been rejected and supp fig 8a should have been in the original paper.
So what is the apparent dynamic here? Mainstream climate scientists make an honest mistake. It appears they realize the mistake and want to correct the record. But the atmosphere is so polarized and the reactions from the skeptic side are likely to be so triumphal that instead of labeling the revision as a correction, it is a clarification and supplemental data. The journalistic term for this is a rowback.
Just click on the link – really, it won't bite. And then apologise.
In science for policy (as opposed to pure curiosity driven research on the frontier of science), scientists have an obligation to address the relevant issues that the public is interested in. And these issues may not be the key issues that link directly into the decision making process, but may arise for a range of reasons, ranging from gee whiz curiousity, a debate that gets publicized in the media, loss of trust arising from a scandal (climategate comes to mind), and something that is simply perceived as basic.
Let me give another example that is currently raging among a group that I would characterize as political skeptics that are nevertheless very concerned about junkscience (my main engagement with this group is through email, and blog posts on this tend to be on political rather than technical blogs). They are interested in the CO2 greenhouse effect (direct effect). The correctly state that this is not explicitly addressed in any of the IPCC reports (CA did a thread on this a few years ago http://www.climateaudit.org/?p=2570)
This debate is being fueled by the identification of this document on the NASA website for highschool students http://canadafreepress.com/index.php/article/2384…
See Figure 1; the greenhouse effect is missing from the earth's energy balance. This is being interpreted as NASA quietly removing the greenhouse effect from its documents. As far as i can tell, this doc had to be written sometime 1988-1995, given the affiliations of the authors. Gavin, need your help in removing this doc from the NASA website (I emailed a few people, no reply).
So what should scientists do about this? This is obviously an issue to be concerned about (erroneous doc at NASA website, no documentation in IPCC). Skeptics are turning out much quackology on this subject, but some physicists are now entering the dialogue and raising what may be some valid points. And in my own investigation of this issue, the definitive paper on this seems to be published in 1998, Myhre et al. (1998) http://folk.uio.no/gunnarmy/paper/myhre_grl98.pdf. Since then, there have been improvements to linebyline radiative transfer codes (notably in the water vapor rotation band), these calculations should be redone. Such calculations can give us the downwelling IR flux, but how does that actually translate into a global surface temperature change? Requires some pretty complex surface temp models (for land, snow/ice, ocean). So it can be argued convincingly that this problem has not been adequately addressed.
Researchers in a community are subject to groupthink, which is a form of intellectual laziness whereby we think that certain problems are already solved, and we focus on a few scientifically trendy issues. But being poked by the public can help us see our scientific problems in a new light, and i think we need to embrace this.
Gavin–
Which link do you want people to click? The one too
Mann et al?
I clicked. The case light blue "NH CPS minus 7 WO tree rings" shows much, much larger variability in the reconsruction, including excursions to -1.4C and +0.7C. In contrast, the original NH CPS rarely rises above 0.2 and never below 1.0C.
How can you characterize this as "(it made almost no difference to the final reconstruction). " Since the purpose of the reconstruction is to find out temperature in the past, I should think this is a notable difference.
On the other hand Willis– is that figure relevant to your question. Because the "wo both" part sure as heck does have a hockey stick.
Perhaps you can't go there until the matters you raise in your own comments are addressed to your satisfaction. So be it. Gavin believes they have been addressed. So where do we go from there? What's the meeting ground where other dialogue can take place?
Surely the next step should be for the critics (if they feel that their points are actually substantive) to publish a scientific paper which shows the effect of their criticisms on the Mann08 results.
Sadly, this is not true. Contrary to Gavin's claim, Figure 8a does not show the situation when neither the tree-ring nor the Tiljander proxies are used.
Look at the light blue line labelled "NH CPS minus 7 w/o tree rings". Then think about how this demonstrates Gavin's point about having to explain things again and again and again and again and again…
All,
The polarized dynamic that scac identifies (and which we all can agree on) is precisely why I've discouraged people from debating Tijlander in this particular thread. The issue has a Groundhog Day quality to it that Bill Murray would appreciate.
That said, I appreciate that everyone has remained civil, and can understand why the differing parties have a hard time accepting the other's explanation.
I think Judith Curry's latest comment raises some interesting related issues which I would encourage people to engage with. It would be great if Gavin could stick around and discuss with Judith this aspect of the debate.
scac,
With respect to the two sides talking past one another: I am making a good-faith effort to adhere to the host's request to not focus on the technical aspects of the use of the Tiljander proxies in Mann08. What Gavin, Willis, and others do is obviously beyond my control.
This necessarily means that my comments will appear to be non-responsive to some of the points that Gavin and others raise.
As far as your interpretation of the reconstruction labeled "NH CPS minus 7 w/o tree rings" — You make an excellent point in highlighting this result (as Gavin did at RealClimate, I believe, and also earlier in this thread). It indeed seems that non-tree ring proxies yield similar reconstructions to the tree-ring-including reconstruction (black line), whether theTiljander proxies are included (dark blue line) or excluded (light blue line).
Three remarks.
1. The Fig. S8a that we are discussing is the third version that has been posted by Prof. Mann. It isn't present at the PNAS website, nor is it linked. People who work from the SI downloaded from the PNAS website will be unable to follow this exchange.
2. The fact that Fig. S8a needed two corrections highlights that the calculations behind these reconstructions are complex, and errors are possible.
3. There are subtler problems with this result, if indeed the Tiljander proxies are uncalibratable. It would strongly suggest that the addition of invalid data leads to a reconstruction that is nearly as good as one that is built on valid data. This ought to be a red flag, in my opinion.
Another point, before i tune out for the morning. Steve Bloom raised the issue of deep expertise and intuition amongst the "professional" researchers. The intuition can be developed only with experience and over time. The intuition is especially valuable in understanding where the "frontier" is and posing good scientific questions to pursue in research. But intuition is no guarantee at all of technical expertise in addressing a problem or making a coherent and logical scientific argrument. Meteorologists, geographers and some geologists have strong intuition but can be weak on technical skills and deficient in making scientific arguments. So the difference between the "elite" and citizen scientists (the distinction between scientists employed in universities/govt in climate research vs the others) is that the citizen scientists often have deep technical skills and good understanding of logical arguments, and this makes them very effective as "auditors", if not producers of original research on the topic.
Judith,
Whether it's good for climate science to have legions of well educated people delve into very specific details of one aspect of the science all depends. It looks like many of them have a deep felt contempt for climate science and often miss the forest for the trees. That makes it very hard to see their energy as positive to the scientific and policy related discussions.
I agree that it would be very worthwhile to figure out how to put this energy and expertise to productive use, rather than A) dismissing it and B) rather than it being put to destructive use, as a lot of it currently is.
Judith,
This is an excellent point about the value of "citizen scientists." I learned about this first hand during my years as an editor at Audubon magazine. In fact, I wrote a number of "citizen science" related stories, esp about extraordinary birders who had keen identification skills and a deep knowledge of a species history, and who participated in conservation initiatives. Here is one story where the main character and talented birder is a pharmacist http://www.audubonmagazine.org/features0212/citiz…
Of course, anyone familiar with Audubon's annual x-mas day birdcount http://www.audubon.org/bird/cbc/getinvolved.HTML
or Cornell's ornithology citizen science program
http://www.birds.cornell.edu/netcommunity/page.as…
will know what I'm talking about.
Lastly, let me also point out that official recognition of the contributions from citizen science is at hand: http://www.nyas.org/publications/Detail.aspx?cid=…
Very, very true, DeNihilist.
The original supplementary material included reconstructions with and without the Tijlander proxies (addressing Amac's point). The additional test (removing tree rings and Tijlander at the same time) was added later (addressing willis's point), after claims (from CA and repeated here) that this was somehow a deliberate omission. Use of whichever proxies you like are a matter of judgment – in Mann's case, he tested both with and without Tijlander precisely because of the questions raised by the data originators. It made no difference. Other authors (and indeed 'auditors') can make different judgments and use the code and data that are online to enable them to do so. None of them apparently have, preferring instead to rehash issues over and over again in order to tie up conversations – including this one.
Ken–
Gavin wrote a claim. He assures us we can verify the claim if we click the link. We click the link to see the image with the blue line you are suggesting we examine. If we look at that blue like and re-read Gavin's claim that that ""(it made almost no difference to the final reconstruction). ", it appears the figure Gavin told us to examine contradicts his claim.
I think this explains why Gavin has to explain things again, and again and again. His first explanation contains a big glaring hole.
Willis–
I just realized this question pointed at you was wrongheaded:
Hockey sticks need both the uptick and the flat shaft. By virtue of no having a flatish shaft, the "wo both" is not a hockey stick. So, clicking on the link to the figure Gavin provided appears to support your point that the analysis "wo both" is not a hockeystick.
As I already noted: it appears to contradict Gavin's statement regarding analysis "wo both" (i.e. "(it made almost no difference to the final reconstruction). ")
Presumably, Gavin can explain his view of what it means for something to "make no difference".
Upthread, scac wrote
As a Reply to that comment, Gavin made some interesting remarks. (Note that the current software implementation requires one to click on the "reply" triangle at the end of scac's comment to see them.)
Gavin wrote,
Gavin,
Both Lucia and Judith Curry have pointed out that climate scientists may believe that they have adequately responded to a question posed by a member of the public, while leaving that question unanswered.
This is the case here.
The question I have posed is,,
"Are the Tiljander proxies calibratable to the instrumental temperature record, 1850-1995?"
Contrary to Gavin's assertion, neither the original supplementary materials nor the twice-revised Figure S8a address this point. "Addressing this point" would take the following form:
"Yes, the four Tiljander proxies employed in Mann08 are calibratable to the instrumental record."
Or,
"No, the four Tiljander proxies employed in Mann08 are not calibratable to the instrumental record."
In my comment upthread that begins
I said,
That comment's point #3 is a good-faith effort to interpret those words. This is followed by
Gavin's words were helpful, with respect to the Calibratable? Question. A follow-up from him on point #4 would be a further positive development, I think.
The link provided to supplemental 8a was directly below the comment "This issue was clearly acknowledged in the M08 paper…" No technical misstatement, but it is misleading.
It is not always correct to say that what proxies you like are a matter of judgment. Basic statistical practice says you need an ex ante hypothesis. If you deviate from the standard hypothesis, you have to justify why. This was not done in the paper, so the proxy should have been excluded. This is not a judgment call.
We clearly differ as to whether the removal of both tree rings and Tijlander makes a difference to the reconstruction. That is a matter of judgment.
"The link" that Gavin supplied is to the modified Figure S8a that is located on Prof. Mann's website at Penn State. Clicking on it should bring up a PDF.
Here it is again, copied from Gavin's comment, since it's devilishly hard to navigate among comments with the current C-a-s threading implementation.
Nov. 2009 version of Fig. S8a.
Note that the Supplemental Information at the PNAS website contained an earlier version of this figure, last time I checked. That could confuse matters, as both the reconstruction traces and the color schemes vary among the different versions.
Gavin
Could you clarify by answering this:
* When you claim " The differences are minimal. ", are you referring to the difference between the light blue trace (wo both) and the black with yellow trace (with both) in the figure provided in the link you referenced in an earlier comment:
>Supp. Fig. S8a
<img src="http://rankexploits.com/musings/wp-content/uploads/2010/06/MannFigure.jpg" width="300">
(I hope the image shows so people don't have to click.)
If that is the figure you intended to link the following discussion is germane.
In the lined figure, the blue trace ("wo both") indicates much warmer temperatures in the the earths' more or less recent history. It appears to indicates that natural variability could explain temperature anomalies exceeding to 0.7C sometime between 600-800. This is almost as high as the highest values in the thermometer record, which, at least in the figure, is shown to be about 0.8C.
In contrast the black trace ("with both") indicates temperature no higher than 0.2C. This would suggest that current anomalies far exceed those that occurred during recent history.
To my mind, these are very different conclusions– particularly in the context of the purpose of paleo-reconstructions.
My current reading is that it very difficult to square the appearance of that graph with your claim that dropping both Tijander and Bristlecne pines makes very difficult with the appearance of that figure . In contrast, the figure appear just as willis said: If you drop both, ther eis no hockey stick. (I understand Willis's view is a hockeystick requires both the blade and the flat shaft. Lacking the flat shaft from 400-1900 is "not a hockey stick.)
Have explained why my interpretation is incorrect somewhere? If not, then I suggest that the reason people continue to question you on this topic is that it appears the evidence you link to support your claim not only fails to support it but actually contradicts it.
You could solve the communication problem that frustrates by by either:
a) Elaborating to explain how you define "The differences are minimal." Quantifying might be useful.
b) Adjust your claim.
c) Get in the habit of linking to evidence that will clearly support your claim, rather than linking to evidence that appears to contradict your claim.
LOL, 'reflux reaction'. I'm gonna borrow that.
Stepping back for just a second, there are some basic observations that I'd like to make.
It's a sign of where the debate is today that there are so few neutral sites for this type of conversation. Gavin has one of the most highly-trafficked weblogs available as a forum. It's pretty easy for me to volunteer reasons why this dialogue isn't happening there (moderation policy, reputational risk, prior bad experiences felt by those he wishes to engage with, etc.), but I'd be interested in Gavin's opinion on this.
Keith, you did a good job of laying down the rules of the road for this, and once again I'd like to compliment you on how you're approaching this overall, and I am not just referring to this thread.
I still think a wiki with a charter agreement framework where people can sign on as agreeing to specific points by invitation would produce a map of what is still left to debate. Those still in question could be unpacked still further, a process we see above in this thread.
I'm not saying we all would start singing Kumbaya together, but I really think that there are a lot of points still bandied about the blogosphere that are actually no longer in dispute by the veterans, and that taking an issue like the case study used here and breaking it down to a bullet point list would clarify issues under discussion.
The link provided to supplemental 8a was directly below the comment “This issue was clearly acknowledged in the M08 paper”¦” No technical misstatement, but it is misleading.
Well, “This issue” in Gavin’s post clearly referred to the Tiljander series alone, not to the effects of removing Tiljander+trees. So I don’t see anything misleading here – the original S8 figures did contain reconstructions both with and without Tiljander, which showed the lack of effect of removing this series and other “uncertain” proxies.
Gavin’s post at #54 explains the origin of the later “S8a” figure (which includes the “neither Tiljander nor trees” curve) – namely, further accusations of dishonesty from certain influential skeptics.
Amac: “Are the Tiljander proxies calibratable to the instrumental temperature record, 1850-1995?”
I think that people have been trying to give you the following answer:
“We don’t know, because it depends on whether the modern anthropogenic effects in Tiljander’s data actually erased the temperature signal – something that is very possible, but not certain. Things being so, we can do either of two things – use the series, or not. Being wary of a priori decision, we do both. Turns out, it doesn’t change much concerning the exceptional status of late 20th century warming.”
Apparently, you and scac don’t find this answer very satisfying. That’s fine.
Keith, although I understand your concerns about going over Tiljander once again, it seems to me that this thread has somehow turned into the perfect example of how scientists can reach out to doubters as long as civility and assumption of honesty are maintained. Importantly, most of the Tiljander “talking points” that haunt the blogosphere have been put forward, and addressed (satisfactorily IMHO – YMMV). So ironically this thread may well turn out to be the One True Final Tiljander Thread. Certainly I could see myself linking to it in the future.
Lucia writes re the updated fig 8a:
"In the lined figure, the blue trace ("wo both") indicates much warmer temperatures in the the earths' more or less recent history. It appears to indicates that natural variability could explain temperature anomalies exceeding to 0.7C sometime between 600-800. This is almost as high as the highest values in the thermometer record, which, at least in the figure, is shown to be about 0.8C."
*Almost* as high as the current period (once, circa 700AD), and occurring in a region of *much greater short-term variability* on the graph, than the current period.
Is the blue proxy curve circa 700AD as accurately reflective of actual temps as it is post 1900?
Are we to adduce from it that natural variation is a 'likely' explanation for the recent behavior of the curve(s), or a 'possible' explanation, or perhaps just a 'not impossible' explanation?
Toto,
Given the display of civility and the seeming forward motion of the Tiljander line of questioning–and Gavin's willingness to engage on some of these questions, I'm going to cease trying to dampen the dialogue. Some people seem to think this thread has the potential to advance the ball, so let's let it play out.
I'm doubtful Gavin agrees with this assessment but he's been kind enough to stop by and step into it a bit, even if just to reiterate his main point that there's nothing to respond to anymore. If y'all want try to convince him otherwise, knock yourselves out. Just please continue being polite.
But if this thread turns into tit-for-tat waged by proxies, I'm pulling up the carpet.
As an editor and writer I live by the maxim: is this advancing the story, or in this case, is this advancing the debate. Whether we can collectively succeed with this thread should become apparent very soon.
Tom Fuller, thanks for the compliments, but if we want make all parties feel welcome here, let's try and avoid even backhanded digs at others. I happen to think RC is as a valuable scientific forum that also serves a public interest. Does it work to everyone's liking? No, of course not. And being a tribal member of the journalistic establishment, I've taken a few potshots at them in recent months. But I'm not weighted down with any baggage regarding RC.
So in the spirit of making all parties feel welcome here, let's not dwell on one's one negative experiences with a member of said party.
Lastly, please note that I will be in a long NYU mtg from 4-7 (EST) and will be unable to approve comments that require moderation during this time. I'm still being held hostage to this comment software and am at my wits end with it. So bear with me for the next few days as I figure a better way towards improving this system or a return to the old one. Thanks, Keith
Hi Keith, no disrespect for RC intended. I gave Gavin my blogger of the year award for heroic performance right after the email leak, actively moderating and responding to 2,000 comments on two posts in about 72 hours.
I disagree with them on many points as well, but meant no offense.
Gavin: Thus what we have is not scientists refusing to engage with serious questions, it is the critics refusing to accept the answer.
Or actively distorting the answers they receive: http://deepclimate.org/2010/06/15/mike-hulme-sets…
I'd love to state that at his blog, DeNihilist … but I am ruthlessly censored there … science at its finest.
toto, in the upthread comment beginning "The link provided to supplemental 8a was directly below the comment…, you wrote
I agree that "whether the modern anthropogenic effects in Tiljander's data actually erased the temperature signal" is a potentially useful way to get at my Calibratable? Question. Let's look.
Here are some reasons to think that the non-climactic signal has overwhelmed the climate-related signal, beginning around 1720 and getting progressively worse through the 20th century. It may be helpful to get a picture of the proxies, either as Mann08's Supplemental Figure 9, or as they are presented in Tiljander's original Boreas, 2003 paper. Both are linked here.
1. Tiljander et al. caution that this is the case. Page 572:
Page 575:
It is possible to discern the effect of the 1967 bridge construction as a spike in all four of the Tiljander proxies (Mann08, Fig. S9).
… Continues in Part 2 …
… Continuation from Part 1 …
2. Tiljander et al provide interpretations of the meaning of three of the proxies in the pre-1720 period when climactic influences predominated.
2a. lightsum is a measure of mineral material in each varve. The authors claim that higher lightsum is associated with wet, cold winters that produce more winter snowpack, so that more inorganic silt is carried into the lake during the spring melt.
2b. darksum is a measure of organic material in each varve. The authors claim that higher darksum is associated with with warmer, wetter summers, where streams carry more organic material into the lake.
2c. xraydenseave (XRD) is the X-Ray density of each varve. This is in a sense a mix of lightsum (very dense) and darksum (not very dense). The authors claim that higher XRD is associated with a colder, wetter climate.
2d. thicknessmm is the thickness of each varve in millimeters. The authors do not assign a meaning to this proxy.
Thus, according to Tiljander:
Higher lightsum, Colder
Higher darksum, Warmer
Higher XRD, Colder
Higher thickness, No assignment.
Contrast this with the way that these proxies are oriented in Mann08, for both the CPS and the EIV reconstructions.
Higher lightsum, Warmer
Higher darksum, Warmer
Higher XRD, Warmer
Higher thickness, Warmer
Mann08's interpretations are Inconsistent, Consistent, Inconsistent, and (possibly) Inconsistent with the detailed interpretations offered by Tiljander et al.
The text of the paper and of the SI do not discuss these inconsistencies. (In my opinion, the authors were not aware of it: an honest mistake.)
In his Reply to McIntyre and McKitrick's Comment in PNAS in 2009, Prof. Mann does not acknowledge these inconsistencies.
Neither the paper's authors, nor Gavin, nor any other climate scientist, nor any AGW Consensus advocate has, to my knowledge, asserted that the authors of Mann08 affirmatively chose their unconventional interpretations. Eli Rabbett (at Stoat) and Steve Bloom (earlier in this thread) have claimed that the authors could have, and might have, done so.
That is indeed correct. However, it seems to me that in that case (a) the authors should have explicitly so stated, and that (b) rigorous peer-review should have led to the Editor's insistence that the authors explicitly explain their unconventional interpretations.
3. In a 2009 Science paper, Darrell Kaufman and co-authors pre-published a draft paper with one of the Tiljander proxies in its inverted orientation. Upon learning of Steve McIntyre's criticism, Kaufman et al. corrected their manuscript so that the proxy was used in the orientation proposed by Tiljander. This episode is mentioned in a couple of Climategate emails.
In conclusion, I have laid out a case for a one word answer to the question
"Are the Tiljander proxies calibratable to the instrumental temperature record, 1850-1995?"
No.
A detailed discussion of the inverted XRD proxy is presented in the post The Newly-Discovered Jarvykortta Proxy — II.
What is the strongest case for “We can’t tell?” What is the strongest case for “Yes”?
In my opinion, deducing that the answer must be “We can’t tell” or “It doesn’t matter” from the tracings in the twice-corrected SI Fig 8a is a very weak argument.
Willis, remember I asked that the personal grievances be checked at the door.
Gavin, my apologies. I had clicked on your link, saw it looked nothing like the Figure 8a in the Mann2008 paper and didn't say Figure 8a, saw it was not published until 2009, assumed your link was incorrect, and went back to the paper. You had said that:
However, both of the possibilities were not shown in the M08 paper as you claimed, so I fear your claim was far from clear. To avoid confusion you might have mentioned that this was a revision from a year later, not (as you claimed) what the paper originally said.
You are correct, they later published a figure which looks nothing like 8a. However, their figure (without both sets of proxies) totally substantiates my claim. Taking out both the bristlecones and the Tiljander proxies makes a very large difference in the early years of the reconstruction. With the bristlecones and the Tiljander proxies, the most recent proxy values were equal to or higher than historical values.
Without them, however, things are very different. The historical values dwarf the current values, and lead to a very different conclusion than the one drawn in the original paper.
Which was my point.
Lucia, the "wo both" only contains a hockey stick if we include the instrumental data. I see no theoretical basis for that inclusion, nor is one presented in the paper. In general, proxy and instrumental data cannot be compared directly.
For example, note the almost 0.4°C difference between the "wo both" reconstruction and the instrumental data around 1960. Given those differences, we cannot simply add the instrumental data to the mix.
I don't think it matters much which of your 3 explanations is best, unless we are trying to prove that AGW does not exist (which I doubt anyone here is trying to do). What seems most important to me is to have data and analysis that is as clear and valid as possible.
Also of some importance is an understanding of how much variation in temperature the biosphere has tolerated in the past. That provides some information on balancing mitigation and adaptation strategies.
I am career computer programmer and businessman, and have spent some time at multiple sites watching these dialogues.
For what its worth, as long as people like Gavin think it is ok to brush off serious questions from serious questioners, there will not be closure on the basic issue. Perhaps it is their perception that the questioners are somehow stooges of the oil companies, or are folks without the ability to change embedded opinions, or maybe there is another explanation.
A simple response to questions posed by Lucia or Willis would be a courteous and positive way to move forward. Continued vague references to clicking a link that everyone has clicked is just another way to not make any progress and continue wasting time here and elsewhere.
I sure hope Gavin has time to address Lucia's last comment above. She raises issues that are substantive and important. Understanding why Gavin and Lucia reach such divergent conclusions based on the same graph would be (I think) remarkably informative.
The way that this thread has avoided the Tijander proxies is nothing short of hilarious. I hope people who are not active in the debates about climate science can see it for what it is.
AMac withdrew from participation on my blog when I refused to take a position on the matter. Just by virtue of being a climate scientist and agreeing with the consensus in no way requires me to have an opinion on this matter. It is, in fact, unambiguously unimportant, as are most of the matters the naysayers bring up. (If 'denialist' is perhaps too harsh, 'skeptic' is too generous.)
agw_skeptic's allegation that these are 'serious questions' and that providing links to answers is inadequate is a common flavor of prolonging the agony. As I said before, asking questions is cheap and answering them effectively is expensive. The people in a position to answer are greatly outnumbered by the people in a position to ask, and indeed most have many other tasks at hand.
To additionally insist that links to prior efforts are off limits is simply another arbitrary handicap added to the ones that are unavoidable. It's simply part of the double filibuster; first, to make life unpleasant and unproductive for climate scientists, providing a disincentive for non-ideological participants; second, to delay policy discussions on the grounds that the "science is not settled", when in fact the crucial core issue is quite clear.
Human activity dominates contemporary climate change. In particular, continued net carbon emissions are risky. These are not topics under active investigation, nor should they be. To be sure, the public must get a much better grasp of the outlines of the problem, but please, let's not mistake argument for argument's sake as being helpful. This mistakes legalistic argumentation for scientific argumentation.
The people harping on Tijander see themselves as being in a contest that they want to win. The people who would like to move on see twenty years of policy delay, leading to a necessity for large decisions on short time scales, and resent this crucial conversation being dragged down by obvious minutiae.
Michael,
You're waging the proxy battle with several assumptions: that "people harping on Tijander see themselves as being in a contest that they want to win." And on the other side, the people like you, who "resent this conversation taking place" on the assumption that it leads to additional policy delay.
Why can't this just be a science question unencumbered with people's assumed motives and unrelated to the policy equation? It may not be a science question you or Gavin feel is worth addressing anymore, but if it has no "import" to the larger AGW case, then what's the harm?
Keith,
Yup, this seems to me to be a simple case where Gavin looks at a line of a graph graph and sees one thing, while Lucia looks at the same line on the same graph and sees something quite different. Since both are experienced readers of graphs, and assuming both are saying what they honestly believe, sorting out how they reach such different conclusions would be most informative.
Keith, the censorship at RealClimate is central to the theme of this thread. How is my comment out of line? I am glad to restate it in its most factual form:
I'd love to state that at his blog, DeNihilist, but I am censored there, so I cannot do so …
How's that? No personal anything, just the facts.
MT, you say
This is not quite correct. I started commenting at Only In It For The Gold, but that drew to a close. An on-topic comment of mine failed your moderation. Then an OIIFTG "regular" offered an insult to me. My civil, issue-oriented response also failed moderation.
All of which is fine. OIIFTG is your blog, and you put up some excellent posts. I read it sometimes, but will write in only rarely.
"Why can't this just be a science question unencumbered with people's assumed motives and unrelated to the policy equation?"
If that's a serious question, Keith, it is seriously naive.
Of course, there's no harm in discussing anything among people who actually find it intrinsically interesting.
There's harm in refusing to discuss anything else until this is settled, demanding insistently that other people take "a stand" on it, refusing to accept links to reliably sound scientists who have already examined it, and insistently beating dead horses about it.
There's harm in using a technical controversy (never mind a drummed up one) in deliberately polarizing the conversation.
I think it's stipulated by those who raise the issue that if there were no policy consequences of climate science, nobody would care about bristlecone pines and such. This means that they want people to conclude that what we think about this issue has policy consequences. And clearly, these are the people who (incorrectly) insist that the less we know about climate, the weaker the justification for policy.
It's almost a loyalty oath sort of thing. If you don't "denounce" Mann's use of the suspect proxies (or whoever or whatever minor issue they choose to focus on in a given day) you are quickly cast as a suspicious character.
As for people who think there is nothing incriminating in the CRU emails and refuse to utter their ludicrous name for the relevant controversies, it goes beyond suspicion to certainty of collusion in some awful dark conspiracy having something to do with Al Gore, windmills, and a resurgence of Stalinism…
Look, this isn't what actual scientific controversies look like or feel like. Scientific controversies are energizing, exciting, morale building things. They lead to eager efforts at calculations, experiments, trips to the dusty back shelves of the library, even expeditions.
This is just snarking and hairsplitting.
To a certain extent I agree with Michael Tobis about the overall place of Tiljander proxies in the scheme of things. (Not entirely, as it affects trust in high profile scientists.)
However, that is the case study we were given and it says so on the label. If Michael thinks this is a waste of time, he can go hang out at Bart's or Lucia's. I am interested in how this turns out.
I am more interested in state of play assessments on sensitivity, what we are learning about the interplay of CO2 and heat between the atmosphere and oceans, and what we are learning about clouds and their net effect on warming.
To the extent that we focus on an issue that, rightly or wrongly, is not likely to see signficant movement (is it realistic to think anyone will experience a Damascene conversion on this subject?), I think KK is correct in suggesting that we set the issue aside and turn to others of (perhaps) even greater substance.
Repeating what I said in email at the time:
I didn't purge your position because I want to misrepresent you. I did
so because the technical issue on which you are focused is not
important to me. I believe it has little enough importance in the
grand scheme of things that I don't want to get tangled up in it.
I don't plan to denounce Mann, and I don't care whether you do or not,
but to do so on my blog has become repetitive, and to use Mann as some
sort of test for my (or others') bona fides is a criterion I do not
accept.
I was, just the same, disappointed that you wandered off. I appreciate
intelligent criticism.
For what it's worth, I have on occasion purged (named regular's) postings. I am sure the case in which he insulted you (which I don't actually recall) was marginal at best. I try to maintain a cordial atmosphere.
I rarely judge matters off topic but I have pretty much eschewed the whole dendrochronology business. The things I think about are so remote from
extracting a scalar signal of modest importance from a noisy record of complex provenance that I don't think I have anything to add. People I respect seem to disagree with your point of view, and I don't think there's any requirement that I sit in judgment on the issue.
If you would like to participate on matters other than dendrochronology, your input would be welcome. Whether there is or isn't a conspiracy is a matter of definition. If you'd like to convince me that you aren't part of some coordinated campaign, discussion of matters other than dendrochronology would help. Of course you are under no more obligation than I am obligated to state an opinion on Mann's work, something which, to my recollection, I have never done.
Probably unsaid, but an important factor here, is that if/when a mainstream climate scientist (other than an author of the Mann paper) makes any substantial comment it could be interpreted as a criticism of the authors. As Judith Curry and others have pointed out, members of the community of card carrying climate scientists just don’t do that .
There are so many new things to work on, and no need to incur the hard feelings that the commenter would experience from publicity about the comment. Look at the way Judith Curry has been allegorically tarred and feathered for even opening a conversation on a skeptic’s blog.
Gavin has not openly stated reluctance to criticize as the reason for not answering the simple questions, but maybe we are supposed to read between the lines.
Another way to say this is that perhaps current rules for civilized behavior amongst the PhD set preclude give and take with anyone except through the medium of peer reviewed papers.
The ivory tower residents may occasionally deem it worthwhile to state that the bloggers can’t or won’t be able to understand the weighty matters of interest to the community of scientists, or even to offer explanations so we can better understand the implications of their publications, but there simply cannot be any give and take on matters of substance.
Perhaps this theory also helps explain why the corrections are seldom acknowledged. Once weather data sets have been used to publish anything, a correction might lead to increased work by the authors on already published work.
There are no brownie points in the publish-or-perish world for retracting or fixing already published papers. No lines are added to the list of peer reviewed paper, the funding for the paper has long been used up, and new work is where the interest and the money are focused.
Well for starters Gavin is a climate scientist and Lucia is not so that they see something different in a graph about a historical climate analogue is hardly surprising.
And it may take Gavin hours of explanation for those of us not trained in climate physics to understand his reasoning. Assuming of course we really want to learn and not defend a point of view.
The real question here: Should Gavin be obligated to spend all that time giving helping us understand all the nuances of climate science?
If so then should I insist my surgeon train me to do the surgery before I let him perform my life-saving operation?
I think you misunderstood agw_skeptic's post — he wasn't against providing links, just saying that once the intended audience had visited those links and had additional questions, the more trenchant the responses, the better.
Regarding the second part of your post, there are folks out there (and I am one of them) who enjoy the nitty-gritty details of the science, want to know what exactly the data supports, and see climate policy as a separate conversation that need have no bearing on the basic science.
agw… You are misinterpreting Curry I think – scientists are a bitchy lot and only agree with each other reluctantly. But in any case your points have already been addressed several times in this thread including my take below:
Well for starters Gavin is a climate scientist and Lucia is not so that they see something different in a graph about a historical climate analogue is hardly surprising.
And it may take Gavin hours of explanation for those of us not trained in climate physics to understand his reasoning. Assuming of course we really want to learn and not defend a point of view.
The real question here: Should Gavin be obligated to spend all that time giving helping us understand all the nuances of climate science?
If so then should I insist my surgeon train me to do the surgery before I let him perform my life-saving operation?
http://blogs.discovermagazine.com/2010/06/16/the-mai…
Stephan, did you visit the link to the jpg of the graph in question? Does it really take more time to refuse to discuss the picture than to comment on whether blue lines are materially different than black lines on a graph? My eighth grader may be able to help. She noticed that the blue lines do indicate wider variances than the black lines.
It seems obvious to me that if Gavin wanted to move forward and stop endless questioning on this specific matter, he would simple confirm the obvious that removing the proxies in question does produce materially different results.
Doing so would amount to confirming that errors exist in the Mann paper and might then obligate someone from the Mann author set to actually acknowledge and correct the error. Providing credibility to a non-scientist and explicitly criticize a mainstream scientist’s work product appear to be far outside the bounds of the rules of the game.
To my original posts: if the mainstream decides as a group that it is to their advantage to dialogue, then they will do so. To go down that road alone means loss of grant money, prestige, and exclusion from the club, maybe even ostracism.
And the benefit of dialogue is the enjoyment of blogging for free with people who visit these blogs. The benefit of winning public support for their policy recommendations might be out there, but that is at best a group benefit and why would Gavin want to reap the penalties as an individual?
I have to disagree with much of what you say. If Gavin would offer *any* explanation for why he concludes that two (apparently) different graphs are in no significant way different, then most any reasonable scientist or engineer (or person!) would be willing to listen to what he has to say. The puzzle for me (and it really is a puzzle) is that two educated scientists, both of whom I am certain are quite smart, could come to such divergent opinions. I have worked in science for >35 years, in a range of fields, with hundreds of scientists and engineers, and I can remember not a single instance where two people completely disagreed about something as simple as whether two graphs are similar or substantially different, and where one refused to discuss why. In addition, I have never encountered a specialist in any field (outside climate science) who could not offer a brief but lucid explanation of a concept in that field, or who suggested anyone who has not intensively studied the field is incapable of understanding that brief explanation.
I completely agree with Gavin that removal of only the lake sediment proxies OR the bristlecone pine proxies changes the results of the reconstruction very little. But removal of both of these series sure seems to me (and I am sure many others) to cause quite a large change in the resulting reconstruction. I would not ask for nor expect any large investment in time from Gavin, but he could certainly provide at least a brief justification for a conclusion which seems so surprising to many. Gavin should of course do as he wishes, but I think investing 15 minutes to explain his conclusion would be a real contribution.
With regard to my surgeon, I would (and have) questioned him closely about exactly why an operation is required, exactly how that operation will be conducted, his rational for using a certain procedure as opposed to a different one, and the relative risks and benefits involved. I sure hope you will do the same if you are contemplating surgery.
Climate science is clearly a broad field with many parts, some of which are only distantly related, but all of which are connected though well known physical science. There are lots of competent and experienced scientists and engineers who understand that well known physical science, and who are quite capable of handling the concepts needed to analyze complex physical systems. To suggest that they are incapable of fathoming a brief technical explanation about climate science strikes me as very strange indeed.
Michael,
Can you identify who you are addressing your comment to, i.e. the person or people who exhibit these objectionable behavors? Thanks.
Michael,
Can you identify who you are addressing your comment to, i.e. the person or people who exhibit these objectionable behaviors? Thanks.
This comment by Judith Curry was made on another thread but strikes me as much more appropriate for this one. http://blogs.discovermagazine.com/2010/06/13/tom-joe…
It seems we perhaps should be talking about this in conjunction with Gavin's original claim.
"confirm the obvious that removing the proxies in question does produce materially different results."
Thus you demonstrate precisely why there is no value in engaging with you. To a scientist, or even a well-informed amateur like me, your interest in this doesn't regard the science at all but rather the extent to which you can find support for conclusions you've already decided to draw. The problem, BTW, is that even if you find a notably warm spot in the last 2,000 years all it would mean is that there's a greater potential for warming in the near future than currently anticipated. That's it, sorry.
Judith,
Good point that scientific intuition doesn’t necessarily translate in good technical skills, and that in plenty of cases there may be citizen-scientists with superior technical skills. But I’d wager that scientific intuition and broad background knowledge of the field is very important in placing results in context and therefore also in making a coherent scientific argument. These (esp the former, the forest-and-trees problem) are what’s missing in many (not all) of the citizen scientsts efforts, and yet, the conclusions are often uncritically taken to be of paramount importance for the field as a whole (eg talk of paradgim shift, Galileo and stuff like that).
Keith,
I don’t think it’s an “assumption” that it (endless and fruitless debates about dendrochronology details) leads to additional policy delay. At the least, I ‘d call it an observation that it’s being used to attempt said delay. (Whether that’s successful is another story)
The problem is that it has no great import to the large AGW case, yet it’s being portrayed and used as if it is. That’s what makes scientists resentful of this dynamic.
All,
My apologies for the continued problmes with the comment software. There were fixes made last night but obvious glitches remain and they are being work on now. I should have them fixed by mid-morning.
Lucia: ” I am looking at this from the point of view of evaluating the truth of Gavin’s main claim which is that he explains things over and over, but the issue won’t go away.”
Well, he was referring to specific accusations, which were indeed repeated in this very thread (“the Tiljander series are contaminated and they didn’t know it” or “they didn’t show the effects of removing both Tiljander and tree ring data”). He pointed out that both accusations have indeed been adressed – in the former case, in the paper itself! So, regarding this particular claim, I believe he made his point.
YMMV.
Lucia,
I am interested to know if, according to experts, the Mann 2008 dataset(s) tells us anything important about what is causing the current warming.
Compared to that question, parsing whether Gavin meant ‘mostly the same’ or ‘the same’ and whether his definition of those meets yours, seems maddeningly trivial.
“Thus you demonstrate precisely why there is no value in engaging with you. To a scientist, or even a well-informed amateur like me, your interest in this doesn’t regard the science at all but rather the extent to which you can find support for conclusions you’ve already decided to draw. The problem, BTW, is that even if you find a notably warm spot in the last 2,000 years all it would mean is that there’s a greater potential for warming in the near future than currently anticipated. That’s it, sorry.”
It is interesting that you think you can read my mind and draw these amazing conclusions. I simply read the comments posted here about whether a simple JPG graph with blue and black lines shows essentially the same numeric result using only the blue or only the black lines. Several other posters have asked the same question the same way. The blue and black lines do have meaning to the paper in question, and several posters have commented that the meaning has not been addressed in the paper in question, nor has Gavin’s statement addressed the obvious visual difference.
I have seen no one except you draw the inference that the difference has momentous implications concerning the world’s warming potential. I am amazed that one who calls himself a well informed amateur can read these posts and stray so far from the clearly stated questions and answers.
Reading these deep dark assumptions about the beliefs and motives of a blog poster into simple basic questions goes back to the original topic of how to have a dialogue. Dialogue at Science of Doom (for example) works because the host patiently and courteously refers questions from the less well informed to well written informational text that actually addresses their questions. Attributing motives to questioners and refusing to dialogue, and to discourage that behavior, appears to be the topic of this thread.
agw-skeptic :
“Probably unsaid, but an important factor here, is that if/when a mainstream climate scientist (other than an author of the Mann paper) makes any substantial comment it could be interpreted as a criticism of the authors. As Judith Curry and others have pointed out, members of the community of card carrying climate scientists just don’t do that .”
That’s nonsense and I doubt JC meant it as you have. Scientists make substantial comments about each others’ work all the time in the press (scientific journals and mainstream) and out of it.
Maybe we are defining ‘substantial’ differently?
agw_skeptic, most scientists — and I daresay at this point, even most ‘skeptics — aren’t skeptical that AGW is happening. That bus moved on long ago. The issues now are entirely about magnitude of both its effects and our responses to it. So your very name puts you way , way out on the fringe. Perhaps that’s why you aren’t seeing responses from scientists that seem ‘substantial’? You aren’t likely to hear responses hinting at malfeasance, fraud, and collusion in a massive conspiracy.
” Dialogue at Science of Doom (for example) works because the host patiently and courteously refers questions from the less well informed to well written informational text that actually addresses their questions. Attributing motives to questioners and refusing to dialogue, and to discourage that behavior, appears to be the topic of this thread.”
Yes, this is certainly the right approach to take.
However, dendrochronology is not a core issue of most branches of climate science, and the criticisms being repeated constantly here and elsewhere are not intrinsically consequential. So the responses may not be as deep or as polished as with radiative transfer. But it’s not as if nobody has made any effort.
So, why the continuing hostile barrage of questions?
Counterattacks like “I have seen no one except you draw the inference that the difference has momentous implications concerning the world’s warming potential. ” or “Can you identify who you are addressing your comment to, i.e. the person or people who exhibit these objectionable behavors? Thanks.” sound reasonable, but they are invitations for mud-wrestling, and divert the question from “what is the importance or relevance of these matters”, which is a crucial one.
Any of us who have accepted these invitations and attempted to get into detail like this find our lives sucked up into astonishingly tedious and childish arguments with people who seem to have a lot of time for this sort of thing. (The CRU email hacking has, tragically, not only bolstered the approach in the particular but has made a general case for politics by felony. I doubt we’ve seen the last of this.)
If anyone not already in the thick of these discussions happens to read this far (an unlikely event to be sure) I’d invite them to have a look at the overall tone of discussion on the “skeptic” sites. It’s easy to see the overall impression that readers of these sites come away with.
The fault may not be easy to attribute to any individual contributor: the “sciencey” ones have cultivated a demeanor of reason, and will claim that the extreme accusations common on the same lists are from others whom they do not deign to censor. But they are acting as lawyers playing to a jury. And the jury happily responds, because the opposition can’t afford good lawyers.
The whole idea is to cast a whole “innocence/guilt” question over a continuum of “what’s the climate sensitivity likely to be, what are the plausible worst cases”? These are the sensible questions, along with “how do we cope with uncertainty?”, that the public should be addressing, and most the efforts of the “skeptics” are aimed at diverting the public’s attention from these really important matters toward petty arguments and personal resentment.
Does this filibustering technique work? I would claim that this thread amply demonstrates that it does.
Not everyone who participates on the skeptic sites is part of the effort to filibuster, and the availability of genuine talent is real. So I commend and support Dr. Curry’s efforts to heal the breech and engage people other than funded climate scientists in efforts that are actually scientific in flavor. Indeed, there are some signs of progress in certain quarters.
But we can’t forget that there is systematic manipulation of the opinions of the public and the press and the policy sector going on here that emphasizes hostility and suspicion and totally diverts from the substantial policy situation as revealed by the science. There is no sign of that manipulation going away, and that is the larger issue that I would like the press to examine.
This thread began with Gavin Schmidt’s frustration about my questioning the validity of the Tiljander proxies as used in the Mann08 paleotemperature reconstructions. He cited <a href=” http://blogs.discovermagazine.com/2010/06/14/our-uncivil-climate-debate/comment-page-1/#comment-7465“>a recent C-a-s comment</a> as an example of this pathology, where I demand retractions and condemn specific scientists for supposed errors or other sins. My view of Tiljander is based on an irrelevancy, and ignores clear acknowledgements in the peer-reviewed literature, and is based on a misperception of the science. If I was sincerely looking for truth, the first time my misperception was corrected (at <a href=”http://amac1.blogspot.com/2009/12/stoat-s-first-debate-on-use-of-lake.html”>Stoat</a> or <a href=”http://www.realclimate.org/?comments_popup=2019#comment-143841″>RealClimate</a>) would have ended the matter. But people like me are looking to bash scientists for another reason. This is why scientists tire of engaging with lay critics, and why the prospect of actual dialogue is limited.
My perspective is different.
Mann08 is a recent effort to reconstruct the history of the Earth’s temperature over the past 1,800 years. The article was published in <i>PNAS</i>, a top-ranked peer-reviewed publication (<a href=”http://en.wikipedia.org/wiki/Impact_factor”>One method</a> places <I>PNAS</i> at position #5, out of over 11,000 scholarly journals.) Prof. Mann and his team are arguably the most prominent paleoclimate researchers in the world.
Both of the reconstruction methods used in Mann08 (CPS and EIV) <i>require that proxy series be calibratable to the instrumental temperature record, 1850-1995.</i> In the Supplemental Information under “Potential data quality problems,” the authors devote 150 words to potential pitfalls with the Tiljander records. Thus, the Mann08 authors and I agree that (1) There is a possibility that the Tiljander proxies might be compromised, and (2) The issue is important.
I’ve distilled my concerns into this question:
<i>”Are the Tiljander proxies calibratable to the instrumental temperature record, 1850-1995?”</i>
Upthread, Gavin <a href=”http://blogs.discovermagazine.com/2010/06/16/the-main-hindrance-to-dialogue-and-detente/comment-page-1/#comment-7517”>strongly asserts</a> that this issue has been fully addressed.
<blockquote>[The answer] has been repeated on RC, Deltoid, Stoat and perhaps other places, yet [AMac] brings it up here again. For whatever reason, the “scientist’s” answer has not been convincing, was not clear enough, or has just not been read.</blockquote>
Gavin’s answer:
<blockquote>Given the methodology used in that particular paper (Mann et al, 2008) (weighting based on a local calibration to temperature in the modern period), the ’tiljander’ proxies can only be used one way. If there is a contamination in the modern period by non-climatic influences (which the originating authors suggested there might be), then they just can’t be used. This issue was clearly acknowledged in the M08 paper and both of these possibilities (with and without ’tiljander’) were shown (it made almost no difference to the final reconstruction).
<a href=”http://www.meteo.psu.edu/~mann/supplements/MultiproxyMeans07/NHcps_no7_v_orig_Nov2009.pdf”>Supp. Fig. S8a</a></blockquote>
Further along the thread, toto <a href=”http://blogs.discovermagazine.com/2010/06/16/the-main-hindrance-to-dialogue-and-detente/comment-page-1/#comment-7683″>offered</a> a more cogent version of the same reasoning.
<blockquote>We don’t know, because it depends on whether the modern anthropogenic effects in Tiljander’s data actually erased the temperature signal ““ something that is very possible, but not certain. Things being so, we can do either of two things ““ use the series, or not. Being wary of <i>a priori</i> decision, we do both. Turns out, it doesn’t change much concerning the exceptional status of late 20th century warming.</blockquote>
I’ll summarize the Gavin/toto answer to “Are the Tiljander proxies calibratable?” as, “Maybe, and it doesn’t matter.”
<b>I think “Maybe” is a dodge.</b>
If “Maybe” means “No,” then Gavin and I are in accord.
If “Maybe” allows for the possibility of “Yes,” then further thought is required. In that case, Mann and co-authors <i>agreed with Tiljander</i> on the meaning of one proxy while <i>opposing Tiljander</i> on the meaning of two proxies.
Mann08’s authors do not acknowledge the issue. Nor have the authors (or anyone else) made a case for their exceptionally unconventional stance on this point. Details in <a href=”http://blogs.discovermagazine.com/2010/06/16/the-main-hindrance-to-dialogue-and-detente/comment-page-1/#comment-7705″>Comment 70</a>.
<b>I think “It doesn’t matter” is a dodge</b>
Firstly, the authors of Mann08 thought it mattered.
Secondly, “It doesn’t matter, on the strength of Fig. S8a” raises a new set of questions, as discussed upthread. Comparison of the light-blue trace to the dark-blue trace in (the twice-revised, non-peer-reviewed version of) Fig. S8a doesn’t allow for clear-cut deductions on the importance of the Tiljander proxies. Reasonable people differ sharply to the correct interpretation.
<b>Summary</b>
This thread kicked off with Gavin Schmidt’s frustration that a basic question about the Tiljander proxies keeps getting asked.
As it draws to a close, climate scientists and AGW Consensus advocates have still failed to forthrightly tackle that question.
<i>Are the Tiljander proxies calibratable to the instrumental record?</i>
For the comment I just submitted (currently #106), I used standard html . This worked for the commenting system that was in use yesterday.
It is essentially unreadable under the current system. My apologies.
All, I have reverted back to the old comment system, which is much easier to use. To embed links, highlight the text in your comment, then click on the third icon from the right in the tool bar.
Note that I have also stopped threading comments (too confusing to follow). Additionally, all comments are numbered in chronological order and there is a permalink.
Thanks for bearing with the previous experiment.
“As it draws to a close, climate scientists and AGW Consensus advocates have still failed to forthrightly tackle that question.
“Are the Tiljander proxies calibratable to the instrumental record?”
Note all the assumptions being made or implied: 1) that “climate scientists” have some responsibility for answering the question 2) that the question has some importance 3) that the question has any impact on the AGW consensus 4) that the question is well posed and 5) that no efforts have been made to engage on this matter.
All these implications are highly dubious at best.
See also:
http://shewonk.wordpress.com/2010/06/14/tricks-hiding-declines-and-other-sleights-of-hand/
also available at http://is.gd/cUlnu
Technical note:
My only complaint with the older comment system (visible as I write) is that it eats paragraph breaks and makes long postings tedious to read. Regular contributors adjust by putting an extra break between paragraphs, which will look peculiar when the new comment system kicks back in.
I **much** prefer that all the comments appear on a single screen. It otherwise becomes awkward to refer to prior comments in the thread.
Michael,
There’s no way any comment system will please everyone. But comments on the old system do all appear on one page. And people will simply have to be mindful of the spacing. Most of us get it right.
Lastly, I suggest people who are prone to write long comments work on cutting down. Brevity is a good thing.
Quick (hopefully brief) response to MT’s numbered points:
1) that “climate scientists” have some responsibility for answering the question?
I believe so.
2) that the question has some importance.
To current discussions of future warming? No. To the credibility of those wishing to lead the discussion? Yes.
3) that the question has any impact on the AGW consensus
Yes. Amac thinks that Gavin is stonewalling and evasive. This issue is preventing two people who believe in many of the same things and desire many of the same policy responses to resolve a difference.
4) that the question is well posed
I understand the question, and the possible answers that would resolve AMac’s dilemma.
and 5) that no efforts have been made to engage on this matter.
I believe efforts have been made to engage. In fact, I don’t recall anyone saying otherwise. But the issue has not been resolved.
Gavin could go point by point through AMac’s post. He evidently has time to engage with us here. I can’t believe it would take that much time to do so. If AMac asks question A and Gavin answers question B, it’s easy to see why AMac would feel frustrated and wonder if he should be suspicious.
I also understand Gavin’s frustration–this need for a paper trail and proper chain of evidence procedures is being imposed post facto.
But we do want to change the world, don’t we? That is what this is all about, isn’t it?
Dr. Bart says – {The problem is that it has no great import to the large AGW case, yet it’s being portrayed and used as if it is. That’s what makes scientists resentful of this dynamic.}
Dr. Bart, I respectfully submit to you, that this is a problem brought about by the AGW proponents. The hockey stick was used deliberately because the effect of the image is powerful. Cover of TAR. Mr. Gore’s movie, even highlighted during the Academy Awards, etc.
I believe the term used is unintended consquences. Through the use of this image, the greatest jump in the polls supporting AGW action was attained. As you state, CS do not see much value in the graph, I say lay people who have spent time learning realize this fact now. But as I stated before, the main part of the audience, just gets snippets, and will never hear about the updates. The hockey stick is a cultural icon now, and unfortunately for AGW progress, in the minds of most lay people, has been debunked.
I would characterize the whole HS phenomonem in poker terms, as a bluff that got called.
Comment #106, re-formatted.
This thread began with Gavin Schmidt’s frustration about my questioning the validity of the Tiljander proxies as used in the Mann08 paleotemperature reconstructions. He cited a recent C-a-s comment as an example of this pathology, where I demand retractions and condemn specific scientists for supposed errors or other sins. My view of Tiljander is based on an irrelevancy, and ignores clear acknowledgements in the peer-reviewed literature, and is based on a misperception of the science. If I was sincerely looking for truth, the first time my misperception was corrected (at Stoat or RealClimate) would have ended the matter. But people like me are looking to bash scientists for another reason. This is why scientists tire of engaging with lay critics, and why the prospect of actual dialogue is limited.
My perspective is different.
Mann08 is a recent effort to reconstruct the history of the Earth’s temperature over the past 1,800 years. The article was published in PNAS, a top-ranked peer-reviewed publication (One method places PNAS at position #5, out of over 11,000 scholarly journals.) Prof. Mann and his team are arguably the most prominent paleoclimate researchers in the world.
Both of the reconstruction methods used in Mann08 (CPS and EIV) require that proxy series be calibratable to the instrumental temperature record, 1850-1995. In the Supplemental Information under “Potential data quality problems,” the authors devote 150 words to potential pitfalls with the Tiljander records. Thus, the Mann08 authors and I agree that (1) There is a possibility that the Tiljander proxies might be compromised, and (2) The issue is important.
I’ve distilled my concerns into this question:
“Are the Tiljander proxies calibratable to the instrumental temperature record, 1850-1995?”
Upthread, Gavin strongly asserts that this issue has been fully addressed.
[The answer] has been repeated on RC, Deltoid, Stoat and perhaps other places, yet [AMac] brings it up here again. For whatever reason, the “scientist’s” answer has not been convincing, was not clear enough, or has just not been read.
Gavin’s answer:
Given the methodology used in that particular paper (Mann et al, 2008) (weighting based on a local calibration to temperature in the modern period), the ’tiljander’ proxies can only be used one way. If there is a contamination in the modern period by non-climatic influences (which the originating authors suggested there might be), then they just can’t be used. This issue was clearly acknowledged in the M08 paper and both of these possibilities (with and without ’tiljander’) were shown (it made almost no difference to the final reconstruction).
Supp. Fig. S8a
Further along the thread, toto offered a more cogent version of the same reasoning.
We don’t know, because it depends on whether the modern anthropogenic effects in Tiljander’s data actually erased the temperature signal ““ something that is very possible, but not certain. Things being so, we can do either of two things ““ use the series, or not. Being wary of a priori decision, we do both. Turns out, it doesn’t change much concerning the exceptional status of late 20th century warming.
I’ll summarize the Gavin/toto answer to “Are the Tiljander proxies calibratable?” as, “Maybe, and it doesn’t matter.”
I think “Maybe” is a dodge.
If “Maybe” means “No,” then Gavin and I are in accord.
If “Maybe” allows for the possibility of “Yes,” then further thought is required. In that case, Mann and co-authors agreed with Tiljander on the meaning of one proxy while opposing Tiljander on the meaning of two proxies.
Mann08’s authors do not acknowledge the issue. Nor have the authors (or anyone else) made a case for their exceptionally unconventional stance on this point. Details in Comment 70.
I think “It doesn’t matter” is a dodge.
Firstly, the authors of Mann08 thought it mattered.
Secondly, “It doesn’t matter, on the strength of Fig. S8a” raises a new set of questions, as discussed upthread. Comparison of the light-blue trace to the dark-blue trace in (the twice-revised, non-peer-reviewed version of) Fig. S8a doesn’t allow for clear-cut deductions on the importance of the Tiljander proxies. Reasonable people differ sharply as to the correct interpretation.
Summary
This thread kicked off with Gavin Schmidt’s frustration that a basic question about the Tiljander proxies keeps getting asked.
As it draws to a close, climate scientists and AGW Consensus advocates have still failed to forthrightly tackle that question.
Are the Tiljander proxies calibratable to the instrumental record?
Toto-
<blockquote>(“the Tiljander series are contaminated and they didn’t know it” or “they didn’t show the effects of removing both Tiljander and tree ring data”). He pointed out that both accusations have indeed been adressed ““ in the former case, in the paper itself!</blockquote>
I think you are misunderstanding both the questions people are asking Gavin, and also the criticisms of his answer. I might suggest that you are assuming that people asked the questions Gavin says they asked, and that Gavin’s answer to their questions is adequate because Gavin tells us his answer is adequate.
I think what willis was saying is <i>not</i> that the effect of both being removed was not examined <i>in the paper</i>. What he was saying had two prongs:
a) the first answer Gavin posted <i>here</i>, which Keith ran as the “blog posts”, does not mention what happens to the proxy reconstruction if both are removed, and
b) willis claims that if Gavin extended his answer to discuss that effect, he would have to admit the the effect on the reconstrucion is <i>not</i> minimal.
So, basically, Gavin’s answer <i>posted here</i> was avoiding an important point about the results in Mann08.
As far as I can say, what willis said was correct on both points:
a) Prior to willis’s question, the wording of the ‘answer’ Gavin posted <i>here</i> initially did not not discuss the issue of removing both and
b) If Gavin extended his answer to discuss that effect, it appears Gavin <i>should</i> have to admit the effect on the reconstructions is not minimal, it is <i>substantial</i>.
After this, Gavin returned. He fired out a torrent of complaints which I think are unjustified but not worth discussing. Then if I understood Gavin correctly, made this claim: If you remove the effect of both, the effect on the reconstructions is minimal providing a link to a figure as evidence. That is to say, he contradicts Willis’s claim (b).
Now, <i> in principle</i> this answer from Gavin should put the issue to bed.
The only difficulty is that if one clicks the link and examines the figure Gavin provided as proof to demonstrate the effect on the reconstructions is minimal, it appears Gavin’s claim is simply incorrect. Inspection of the figure supports — in fact appears to prove– Willis’s point (b).
To my way of thinking, unless Gavin comes back to further explain why Willis’s point (b) is incorrect , we have an example where Gavin continue to be asked questions, because his answer was worse than merely weak, it appears his basic claim may be flat out wrong.
So let’s go back to Gavin’s closing complaint:
<blockquote>Thus what we have is not scientists refusing to engage with serious questions, it is the critics refusing to accept the answer.</blockquote>
What seems to have happened in comments here is a scientists gave what appears to be an answer so flawed that people of good faith could easily consider it to be flat out wrong. Critics refuse to accept the answer given by Gavin– a scientist– because the asnwer appears flat out wrong. People who support Gavin are suggesting the critics refusal to accept the answer somehow reflects badly on the critics. We await to see if Gavin returns to explain why his critics should not consider his answer to willis point (b) either flat out wrong or at best, highly misleading. Because currently, Gavin’s claim appears to be contradicted by the evidence he gave to support it.
http://blogs.discovermagazine.com/2010/06/16/the-main-hindrance-to-dialogue-and-detente/#comment-7820
Steven Sullivan’s text:
“But we can’t forget that there is systematic manipulation of the opinions of the public and the press and the policy sector going on here that emphasizes hostility and suspicion and totally diverts from the substantial policy situation as revealed by the science. There is no sign of that manipulation going away, and that is the larger issue that I would like the press to examine.”
Steven. How is your current approach working for you? Are you seeing a new massive public acceptance of your concerns and policy recommendations? I changed my post name to address your comment from agw to cagw_skeptic99 because it is the catastrophic part of your belief set that hasn’t been convincing to me. Everyone with an elementary understanding of the physics will agree that increased atmospheric CO2 causes less energy to leave the earth and thereby warms the atmosphere when compared to the same circumstances and less CO2.
Want to get this community to work with you rather than against you? My opinion, supported possibly by only me, myself, and I, is that you won’t get there by slandering “systematic manipulation” those who question your science. I regularly post questions about the certainty, data quality, computer models, and even the motivations of those on your side of the spectrum. After all, there is far more money pouring into the mainstream side than anyone has ever found on the skeptic side.
My own believe is that unless climate science decides to open its data to auditing by folks outside your circle of true believers, the public trust will continue to erode from its already low level.
If you goal is truly to change behavior, maybe more of the same isn’t the best way to achieve your goal.
For example, instead of your community belittling and opposing Anthony Watt’s surface station project, how about welcoming it with open arms and applauding his efforts to improve the quality of the climate data? Several of you have asserted that it won’t matter, won’t change anything, etc. Has anyone thought through the consequences of actually acting like you care about data quality and maybe didn’t have the money to do what he is doing and thanking him and his volunteers (I am not one) for their efforts? That would be a step towards getting the press and the public on your side, but then that might be too much like an Irish Catholic blessing his daughter’s marriage to a Protestant.
Your community’s angry reactions to the criticism and refusal to engage in meaningful ways, as evidenced here over and over again about simple blue and black lines on a graph, are blocking your own stated goals. Which is more important to you?
I’ve been enjoying the dialogue on this thread (among others), but haven’t contributed, as any points I might make are being well presented by others. But I wanted to pick up on a comment by mtobis which hasn’t been addressed:
“And clearly, these are the people who (incorrectly) insist that the less we know about climate, the weaker the justification for policy.”
Am I reading this correctly, that Mr Tobis’ claim is that it doesn’t matter how certain we are of our climate knowledge?
MT says:
“Note all the assumptions being made or implied:
1. that “climate scientists” have some responsibility for answering the question.”
Well, that depends doesn’t it. I completely admit that individuals within the climate science establishment can choose to answer the question as they see fit. I am not going to go stand in Gavin’s office and pester him if he fails to answer it. On the other hand, reframing questions such that they instead answer issues that Gavin decided he would rather discuss instead of what the questioner is actually asking is not going to do a whole lot of convincing. If you just want to whine that the skeptics aren’t taking your assertions of relative importance on faith, you are doing well. If you are actually trying to convince someone not predisposed to a specific faith, you are failing badly.
MT says:
2. that the question has some importance
Are you then asserting that you are the ultimate arbiter of what is important ? It has some importance to me. Now, this is pretty small potatoes in the general argument and I do believe it tells me next to nothing about the general warming effects of CO2. What it does do, is allow me to calibrate my “network of trust”. How do I rationally decide which voices I listen to and which I regard with skepticism ? One of the best ways is to closely watch the argument patterns and data presented by the opposing sides. If someone is in spin mode on items I can personally inspect, the chances of me taking anything else they say on faith are remote.
MT says:
3. that the question has any impact on the AGW consensus
Contrary to your incorrect assumption, I have no interest in the tribal consensus. I am motivated mostly by the interesting physics and secondarily by the psychology on display.
4. that the question is well posed
Argue by assertion much ? As far as I can tell, “not well posed” means, I don’t want to answer that, or I believe you shouldn’t be asking that question because it does not fit in with the story I am trying to sell. Linguistically, I assure you that the question is meaningful. Also, it is worth noting that there is an underlying question attached to this one. “Can I trust you to answer a question that is politically inopportune in a straight forward and honest fashion ?”. This helps me decide whether you are fish or foul: politician or scientist. If you are in political mode, I am probably going to ignore anything further you say.
While this probably doesn’t matter to you at all, I would note that if you are going to complain about being utterly unable to convince skeptics perhaps there is a correlation here ?
MT says:
5. that no efforts have been made to engage on this matter.
Well, apparently your efforts are not succeeding. Perhaps if you addressed the question actually being ask instead of the one you wanted to answer you might actually convince someone ?
Keith, I understand you are working on your reply software. That’s good, because what you are using now makes the thread almost impossible to follow (and I know the subject well).
For starters, you desperately need software that lets the poster preview his/her post. Poster children abound above, sigh.
I hope you take the time to repost some of this cleaned up, ruthlessly pruning trolls, spin & BS. There’s some cool stuff here, that might even advance our understanding.
Kind regards,
Peter D. Tillman
Consulting Geologist, Arizona and New Mexico (USA)
Peter D. Tillman
Poster children abound above, sigh.
I resemble that remark! I assumed I can type in html. You could in the old system, but not in this one.
HaroldW:
“”And clearly, these are the people who (incorrectly) insist that the less we know about climate, the weaker the justification for policy.”
Am I reading this correctly, that Mr Tobis’ claim is that it doesn’t matter how certain we are of our climate knowledge?”
The less we know, the less we can rule out worst-case scenarios, such as, say, a 6C rise by 2100.
Dear Gavin,
You really think you are a scientist, and that we are morons, don’t you?
Dhogaza!
The very master of 5th dimension physics is also here! What a party! Lets go back to radiative forcing and the SB models. Whow!
Dhogaza,
Or even more worst case a 6C decline by 2100? How worst do you want to go?
Lucia: The only difficulty is that if one clicks the link and examines the figure Gavin provided as proof to demonstrate the effect on the reconstructions is minimal, it appears Gavin’s claim is simply incorrect. Inspection of the figure supports “” in fact appears to prove”“ Willis’s point
I believe Gavin claimed that dropping the lake proxies has minimal effect on the reconstruction but of the no-tree-rings-no-dodgy-proxies (cyan) line he wrote only that it ‘looks similar, a subjective judgement, that I happen to agree with.
When it is claimed that the no-tree-rings-no-dodgy-proxies ‘makes no difference’ I read that as meaning that the conclusions of the paper are still supported by that version. To recap these were :-
Our results extend previous conclusions that recent Northern Hemisphere surface temperature increases are likely anomalous in a long-term context. 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.
Personally I see no contradiction between these conclusions and the cyan line. Do you?
As one of the illiterate I offer the following.
The “question” is political now. This allows the uneducated, like myself, a point of view. I may/do not understand the science but I do understand “bulldust”. To live at my level it is a life skill.
A question unanswered or avoided raises the “bull” level. Believe me “I am qualified” raises it higher.
Why is my opinion relevant? Because I vote and if you don’t convince me I will vote for the people who will cut your funding or fire you.
Now does my opinion matter? Two years ago maybe not but now I think we “illiterate” are paying more attention and you are correct in assuming there are more of “us” than “you”.
Phil Clarke #125 — I see three issues with the Gavin/toto assertion that the similarity of the light blue line and the dark blue line in Fig. S8a vindicates Mann08’s use of the four Tiljander proxies.
The least important but most ironic one is this: the Fig. S8a in question is not the Fig. S8a in the peer-reviewed paper that was published by PNAS in September 2008. It is, instead the second of two amendments of the original figure, put up without fanfare at Prof. Mann’s Penn State University website in November 2009. In other words, this is “blog-science,” for better or worse.
Second, Gavin and toto are trying to validate a data series by arguing that the results of a series of complex and arcane calculations generate results that are “very” similar, whether or not the Tiljander proxies are used. Gavin and I both think that the light blue and dark blue lines are largely superimposable. But Lucia thinks that the two lines have important differences. Who’s right? What is the extent of similarity that supports the notion that the Tiljander proxies are valid, or “don’t matter”? If McKitrick and Michaels had made a similar argument about measuring latitude in degrees instead of radians, would that have justified a refusal to correct their published findings?
Lastly, let’s stipulate that Mann08’s use of the Tiljander proxies was indeed valid. Unfortunately for Mann08’s authors, this leads directly to a follow-up question. In their 2003 Boreas paper, Tiljander et al. assign these values to their measures (#70 upthread) —
Higher lightsum = Colder / Higher darksum = Warmer
Higher XRD = Colder / Higher thickness = Not assigned
Mann08 uses the following assignments —
Higher lightsum = Warmer / Higher darksum = Warmer
Higher XRD = Warmer / Higher thickness = Warmer
See the differences? Suppose Tiljander had reported, “Mild winters cause earlier opening of pussy willow buds and earlier blossoming of cherry trees,” but Mann08 used their proxies so that mild winters correlated with earlier opening of pussy willow buds and later blossoming of cherry trees.
That would be a remarkable switcheroo, and in fact Mann08’s use of the Tiljander proxies does include two remarkable switches.
The paper is completely silent on this issue. The inverted use of two data sets are not described and not justified.
The supporters of Mann08’s use of the Tiljander proxies — including Gavin and toto — are also silent on this issue.
Why?
Keith wonderful thread. I would like to point out some problems with MT’s and others’ claims concerning paleo. It contradicts AR4. I have included some relevant points, there are many others. If you use a wire and frame model approach to Chapter 9 AR4, one cannot claim the reconstructions do not matter. As Tebaldi and Knutti have pointed out in the literature, a model prediction of 100 years may take up to 130 years to determine its correctness. They also agree to, and Knutti may have influenced the italicized quote below.
From the summary at p683 Chapter 9 Attributing Climate Change.
P 683 The Summary “”When driven with estimates of external forcing for the last millennium, AOGCMs simulate changes in hemispheric mean temperature that are in broad agreement with proxy reconstructions (given their uncertainties), increasing confidence in the forcing reconstructions, proxy climate reconstructions and models. In addition, the residual variability in the proxy climate reconstructions that is not explained by forcing is broadly consistent with AOGCM-simulated internal variability. Overall, the information on temperature change over the last millennium is broadly consistent with the understanding of climate change in the instrumental era.””
P 640 of the IPCC AR4 report, at the end of section 8.6, which is entitled “Climate Sensitivity and Feedbacks” explains the necessity of such presentations in AR4:
“A number of diagnostic tests have been proposed”¦but few of them have been applied to a majority of the models currently in use. Moreover, it is not yet clear which tests are critical for constraining future projections (of warming). Consequently, a set of model metrics that might be used to narrow the range of plausible climate change feedbacks and climate sensitivity has yet to be developed.“ “”
AR4 P600 Chapter 8
There is considerable confidence that climate models provide credible quantitative estimates of future climate change, particularly at continental scales and above. This confidence comes from the foundation of the models in accepted physical principles and from their ability to reproduce observed features of current climate and past climate changes. Confidence in model estimates is higher for some climate variables (e.g., temperature) than for others (e.g., precipitation). Over several decades of development, models have consistently provided a robust and unambiguous picture of significant climate warming in response to increasing greenhouse gases.
Models’ ability to represent these and other important climate features increases our confidence that they represent the essential physical processes important for the simulation of future climate change. (Note that the limitations in climate models’ ability to forecast weather beyond a few days do not limit their ability to predict long-term climate changes, as these are very different types of prediction-
AR4 P601 Chapter 8
A third source of confidence comes from the ability of models to reproduce features of past climates and climate changes. Models have been used to simulate ancient climates, such as the warm mid-Holocene of 6,000 years ago or the last glacial maximum of 21,000 years ago (see Chapter 6). They can reproduce many features (allowing for uncertainties in reconstructing past climates) such as the magnitude and broad-scale pattern of oceanic cooling during the last ice age. Models can also simulate many observed aspects of climate change over the instrumental record. One example is that the global temperature trend over the past century (shown in Figure 1) can be modeled with high skill when both human and natural factors that influence climate are included. Models also reproduce other observed changes, such as the faster increase in nighttime than in daytime temperatures, the larger degree of warming in the Arctic and the small, short-term global cooling (and subsequent recovery) which has followed major volcanic eruptions, such as that of Mt. Pinatubo in 1991 (see FAQ 8.1, Figure 1). Model global temperature projections made over the last two decades have also been in overall agreement with subsequent observations over that period (Chapter 1).
Or take this support of Willis and Lucia:
AR4 P466 Chapter 6
The first (Mann et al., 1999) represents mean annual temperatures, and is based on a range of proxy types, including data extracted from tree rings, ice cores and documentary sources; this reconstruction also incorporates a number of instrumental (temperature and precipitation) records from the 18th century onwards. For 900 years, this series exhibits multi-decadal fluctuations with amplitudes up to 0.3°C superimposed on a negative trend of 0.15°C, followed by an abrupt warming (~0.4°C) matching that observed in the instrumental data during the first half of the 20th century.
Amac: The supporters of Mann08’s use of the Tiljander proxies “” including Gavin and toto “” are also silent on this issue.
I think you meant “supporters of Mann08’s use and non-use of the Tiljander proxies”.
I think this is the crucial point of disagreement: in your opinion, evidently, producing the reconstructions both with and without said proxies, and pointing out that both versions support the conclusions of the paper, amounts to “a dodge” and does not constitute a proper handling of the issue.
By contrast, a lot of people seem to think that it does properly address the issue – by proving it irrelevant. That includes me, and obviously the reviewers of the paper. I’ll be so bold as to assume that it also includes a large majority of publishing scientists.
This is why I think we are facing a fundamental difference of opinion, rather than a communication problem. This is also why I do not predict significant progress on this particular issue among the unconvinced.
Also: What Phil Clarke said. One of the conclusions of the paper is that the CPS reconstruction is unreliable before AD 1000, even using all proxies. The “no-dendro-no-Tiljander” reconstruction largely agrees with the previous one right to that period – including, importantly, the controversial MWP that led to so much heat in previous discussions.
So I think Gavin’s comments are indeed supported by the graph. However I agree that it would be useful to add in a qualifier, such as “for the period that covers the paper’s conclusions”, which might prevent unnecessary confusion.
Phi-
Personally I see no contradiction between these conclusions and the cyan line. Do you?
Sure I do.
I see a contradiction inside the paper and with what Gavin claims. The contradiction in the paper itself arises because conclusion you quote can only be made based on a reconstruction and its associated uncertainty intervals and the cyan line presented to the reader contains no uncertainty intervals.
With respect to the cyan (i.e. wo both line) readers are forced to guesstimate the size of the uncertainty bands on the light blue (cyan) trace are likely to guess the computed uncertainties on the light blue trace would comparable to those surrounding the black line and shown in yellow (assuming that’s what those are). Those bands appear to easily be ±.2C and possibly ±0.3C — with the larger excursions seen in locations where the temperature exhibits local max or mins.
So, many readers are likely to either conclude that you can’t conclude this “Recent warmth appears anomalous for at least the past 1,300 years whether or not tree-ring data are used.” based on the figure Gavin linked. The reason you can’t is that the a) figure doesn’t present the reader sufficient information and b) if the reader tries to guestimate to fill in the information, they are likely to conclude the opposite of what is claimed in the paper.
In contrast, the figure appears to provide uncertainty intervals for the black line, (with both proxies, uncertainties shown in yellow). So, you can make the quoted claim applies correctly to the results for the black line.
But as far as I can tell, based on the figure gavin provides, it appears one can believe that the two reconstructions may well result in substantively different conclusions than those provided in the paper itself.
Of course a reader might do a passel of work to make up for the deficiencies in Mann’s figure and possibly come to the same conclusion he did. Or not. I don’t know. In context of Gavin’s complaint that Mann and others keep presenting answers but people are finding them deficient, I’m just looking at the actual answers and figures provided.
Out of curiosity, did Mann provide any illustration of the “cyan wo reconstruction” with uncertainty intervals? I’d be interested in seeing that, and no, I don’t want to recompute everything myself.
Because for the time being, based on information in images and papers linked here, I’m still seeing a hole in the argument used to support Mann’s conclusion which you, Phil Clarke, quote.
toto
That includes me, and obviously the reviewers of the paper. I’ll be so bold as to assume that it also includes a large majority of publishing scientists.
I’d bet dollars to donuts that the vast majority of publishing scientists have no opinion on the tijander dispute. Paleo climatology being a small field, the number of published scientists who actually have an opinion on this specific issue is likely rather small.
This is why I think we are facing a fundamental difference of opinion, rather than a communication problem. This is also why I do not predict significant progress on this particular issue among the unconvinced.
I agree with you here.
Returning to the difficulty: Gavin is characterizing this difference of opinion about as a misperception of the science and insinuates that people asking questions must not be seeking the truth.
As far as I can see, the discussions fall in the normal range for any question that might arise after a paper is published. I find it very odd to read Gavin’s complaints.
Toto #123 —
Firstoff: we disagree, but you’ve been willing to look at a narrow technical matter without jumping to conflate it with questions about my motives, or the implications for the IPCC, or the effect of a discussion on policy prescriptions. This is refreshing. Before dipping a toe into the Climate Change pool, I had thought this was the generally-accepted approach to handling technical issues, common to all the physical sciences. The exception that AGW Consensus climate scientists have created for their own specialty is troubling, in my view.
On to the substance. You describe the Mann08 authors’ “use and non-use” of the Tiljander proxies. But the authors did screen them. The screen validated them. The SI text includes a 150-word discussion of their possible shortcomings. The proxies are used in the calculations of paleotemperature anomaly traces shown in Figs. 2 (a,b,c,d), 3 (both parts), S2, S4 (8 of 12 parts), S5 (4 of 6 parts), S6 (4 of 6 parts), S7 (a,b), S8 (original and both revisions), S10 (both parts), S11 (both parts), S14 (both parts), S15 (both parts), and S16 (both parts). So in plain English, Mann08’s authors used the Tiljander proxies.
The question that arose is, “are the Tiljander proxies used correctly in Mann08?” In particular,
“Are the Tiljander proxies calibratable to the instrumental temperature record, 1850-1995?”
It’s a simple, direct question about the validity of a data series. I think the best answer to this type of query is also simple and direct.
One simple answer is “No.” That’s the case I’ve presented.
Another simple answer is “Yes.” Nobody — not even the authors or their most ardent defenders — is offering that answer. Curious!
A more complicated answer is “we can’t tell, and it doesn’t matter.” For all the ink that has been spilled on this matter, it took your Comment #63 to give it a succinct phrasing (which was very helpful).
As Gavin (#5, #54) and you (#63) say, this argument relies on comparisons of “with Tiljander” and “without Tiljander” tracings in “Temperature anomaly vs Time” graphs. In particular, the graphs in the original Fig. S8a and the twice-corrected and twice-amended Fig. S8a.
Why rely on a subtle interpretation of the results of a series of complex and opaque calculations that involve the integration of dozens of proxy series, in order to answer a simple question about data integrity? We know errors can creep in to these calculations: Fig. S8a itself required corrections!
If Mann08’s use of the Tiljander proxies was valid, they necessarily were used in an extraordinary fashion. That is, in agreement with the original specialist authors for darksum, but in contradiction to the original specialist authors’ interpretations for lightsum and XRD. See my Comment #127.
This highly unconventional challenge to the relevant scientific subspecialty (paleolimnology) is not mentioned in Mann08. Since it’s unmentioned, it is not justified.
Mann08’s authors didn’t take the chance to address the issue in their 2009 Reply in PNAS. To my knowledge, they have never tackled it.
To my knowledge, none of Mann08’s defenders have ever offered an explanation — preferring silence.
Simple questions deserve simple answers. If complicated answers are required (e.g. “Fig. S8a shows…”), they’ll likely raise additional questions.
Such as, in this case: “Is it acceptable scientific practice for Mann08’s Methods section to be silent on their highly unconventional uses of the Tiljander proxies?”
Once more, a simple question that deserves a simple answer!
@ G. Schmidt, #5
…or (wonder of wonders) actually try and understand why the scientists make the point they do (and no, the answer is not because they are a paid-up member of some conspiracy).
Yeah…well…welcome to our world, chief.
http://www.exxonsecrets.org/index.php?mapid=831
http://www.ucsusa.org/news/press_release/ExxonMobil-GlobalWarming-tobacco.html
http://scienceblogs.com/deltoid/2010/03/naomi_oreskes_on_merchants_of.php
“Special interests have blocked transition to our renewable energy future. Instead of moving heavily into renewable energies, fossil companies choose to spread doubt about global warming, as tobacco companies discredited the smoking-cancer link. Methods are sophisticated, including funding to help shape school textbook discussions of global warming.
“CEOs of fossil energy companies know what they are doing and are aware of long-term consequences of continued business as usual. In my opinion, these CEOs should be tried for high crimes against humanity and nature.”
James Hansen
I thought the point was:
– Mann used a method that mined for hockeystick shapes and gave them undue emphasis in the final curve
– Mann used “hockeystick” series of (a) trees AND (b) Tiljander, which drove his official “include all” output
– Mann claimed that his method was robust because you could remove either one of the above and still get a hockeystick.
– The problem is that applies only if you remove just ONE. If you remove BOTH simultaneously then the result looks significantly different (e.g. MWP). This admission had to be dragged out of him and was not part of the main paper (hence the ad-hoc link given by Gavin).
– another problem I heard is that Mann’s PC method gave a strong _positive_ weight to trees (correlate well with instrumental temperatures) and would have given a strong _negative_ weighting to another series that was the mirror image. The PC method certainly seems a strange form of averaging, if it doesn’t matter if you invert a series! Or did I misunderstand something?
I’m a PhD engineer and my training leads me to think that the main “include all” black line in the graph linked to above is significantly different to the light blue one from removing both trees and Tiljander. But YMMV…
S
Keith wonderful thread. I would like to point out some problems with MT’s and others’ claims concerning paleo. It contradicts AR4. I have included some relevant points, there are many others. If you use a wire and frame model approach to Chapter 9 AR4, one cannot claim the reconstructions do not matter. As Tebaldi and Knutti have pointed out in the literature, a model prediction of 100 years may take up to 130 years to determine its correctness. They also agree to, and Knutti may have influenced the italicized quote below.
From the summary at p683 Chapter 9 Attributing Climate Change.
P 683 The Summary “”When driven with estimates of external forcing for the last millennium, AOGCMs simulate changes in hemispheric mean temperature that are in broad agreement with proxy reconstructions (given their uncertainties), increasing confidence in the forcing reconstructions, proxy climate reconstructions and models. In addition, the residual variability in the proxy climate reconstructions that is not explained by forcing is broadly consistent with AOGCM-simulated internal variability. Overall, the information on temperature change over the last millennium is broadly consistent with the understanding of climate change in the instrumental era.””
P 640 of the IPCC AR4 report, at the end of section 8.6, which is entitled “Climate Sensitivity and Feedbacks” explains the necessity of such presentations in AR4:
“A number of diagnostic tests have been proposed”¦but few of them have been applied to a majority of the models currently in use. Moreover, it is not yet clear which tests are critical for constraining future projections (of warming). Consequently, a set of model metrics that might be used to narrow the range of plausible climate change feedbacks and climate sensitivity has yet to be developed.“ “”
AR4 P600 Chapter 8
There is considerable confidence that climate models provide credible quantitative estimates of future climate change, particularly at continental scales and above. This confidence comes from the foundation of the models in accepted physical principles and from their ability to reproduce observed features of current climate and past climate changes. Confidence in model estimates is higher for some climate variables (e.g., temperature) than for others (e.g., precipitation). Over several decades of development, models have consistently provided a robust and unambiguous picture of significant climate warming in response to increasing greenhouse gases.
Models’ ability to represent these and other important climate features increases our confidence that they represent the essential physical processes important for the simulation of future climate change. (Note that the limitations in climate models’ ability to forecast weather beyond a few days do not limit their ability to predict long-term climate changes, as these are very different types of prediction-
AR4 P601 Chapter 8
A third source of confidence comes from the ability of models to reproduce features of past climates and climate changes. Models have been used to simulate ancient climates, such as the warm mid-Holocene of 6,000 years ago or the last glacial maximum of 21,000 years ago (see Chapter 6). They can reproduce many features (allowing for uncertainties in reconstructing past climates) such as the magnitude and broad-scale pattern of oceanic cooling during the last ice age. Models can also simulate many observed aspects of climate change over the instrumental record. One example is that the global temperature trend over the past century (shown in Figure 1) can be modeled with high skill when both human and natural factors that influence climate are included. Models also reproduce other observed changes, such as the faster increase in nighttime than in daytime temperatures, the larger degree of warming in the Arctic and the small, short-term global cooling (and subsequent recovery) which has followed major volcanic eruptions, such as that of Mt. Pinatubo in 1991 (see FAQ 8.1, Figure 1). Model global temperature projections made over the last two decades have also been in overall agreement with subsequent observations over that period (Chapter 1).
Or take this support of Willis and Lucia:
AR4 P466 Chapter 6
The first (Mann et al., 1999) represents mean annual temperatures, and is based on a range of proxy types, including data extracted from tree rings, ice cores and documentary sources; this reconstruction also incorporates a number of instrumental (temperature and precipitation) records from the 18th century onwards. For 900 years, this series exhibits multi-decadal fluctuations with amplitudes up to 0.3°C superimposed on a negative trend of 0.15°C, followed by an abrupt warming (~0.4°C) matching that observed in the instrumental data during the first half of the 20th century.
As an addendum to this thread, a new (and developing) twist: I just looked back on some September 2008 work by skeptical blogger Jeff Id.
It makes me think that I’ve been wrong to believe that the Tiljander proxies make an outsized contribution to the earlier parts of the Mann08 reconstructions. Jeff Id’s findings are directly relevant to the second part of the “I don’t know, and it doesn’t matter” answer to the Calibratability Question.
To be clear, I’m saying that Gavin and toto may be correct to assert, “it doesn’t matter.” (To the shape of the paleotemperature reconstruction, that is.) This is sketched out further in this comment at Arthur Smith’s post “Michael Mann’s errors.”
As a second addendum: Steve McIntyre has walked through the methods involved in emulating the third version of Mann08’s Figure S8a (the key evidence Gavin linked to with respect to the Tiljander proxies “not mattering” to the paper’s reconstructions, earlier in this thread at #5 and #43).
McIntyre’s post raises doubts about the trusworthiness of that figure. If so, the role of the Tiljander proxies in Mann08 becomes a more open issue, again.
Gavin wrote:
One of the pathologies of blog comment threads is the appearance of continual demands that mainstream scientists demand retractions of published work or condemnations of specific scientists for supposed errors or other sins. Most often the issue in question has been discussed dozens of times previously and is usually based either on an irrelevancy, or was acknowledged clearly in the original or subsequent paper or is based on some misperception of the science. [See Mann et al (2008) paper.] ”
I think Gavin overstates the case here and selecting the Tiljander case provides a poor example. I’ll focus on another example. One that requires No scientific knowledge. Only knowledge of a Map.
Start Here:
http://climateaudit.org/2008/09/22/the-mystery-in-kenya/
http://climateaudit.org/2008/11/09/the-rain-in-spain/
So what we have here is a mistake made by Mann. A mistake found by Steve McIntyre.
Over the course of time I have repeatedly asked people to make the following simple factual statements.
1. Mann made a mistake
2. Mcintyre found it.
3. Mann fixed the mistake.
4. Mann did not give credit to Steve for finding the mistake.
5. The mistake was .5C for the SH over a period of time
Now, I ask people to make these simple comments. They can read the papers and the SIs and follow the trail and see that these are the simple facts. No one, not a single person is able to repeat these 5 factual statements. Gavin, cannot come here and repeat those 5 factual statements. The practical consequence of this is that people will continue to ask the question. Did Mann make this mistake? Did he or did he not fix it? Did he or did he not fail to acknowledge Steve McIntyre?
People will respond.. “it doesnt matter, other studies show, why should he credit steve? steve was mean he deserves no credit, the .5C mistake doesnt matter. “But no one is ABLE to repeat those 5 factual statements. I find that odd. This inability to state facts simply is not isolated to those of us who believe in AGW. Skeptics have the same difficulties agree to simple facts or answering simple questions. I’m waiting for somebody to prove me wrong. To read the links and the papers and to come back and say 5 simple facts.
If history is any guide people will not be able to do that. They will have to change the topic, make some comment about me, or about Mann or about McIntyre. But No one ( ok maybe Amac will) is able to read those posts and the papers and the SI and make 5 little definitive statements. So those questions will get repeated over and over again. Skeptics are not the only ones in denial of the facts. And here is the Odd thing. Skeptics deny important facts. Gavin can’t state 5 little factual statements that make no real impact on the science as a whole or policy. THAT is seriously weird.
Here is an interesting comment from the comment from the Mystery in Kenya Tanzania:
http://climateaudit.org/2008/09/22/the-mystery-in-kenya/#comment-163344
It does not completely answer Steven Mosher’s point. But I surmise it might provide a good start.
Willard,
Your opinion is so 2009.
You are an example of someone who has invested time and resources into this issue and can’t begin to even look for the truth about AGW with all of the Schmidt in your eyes.
Love,
Joe
Times are a changing son.
AMac, Mann did address the issue in his reply in PNAS. He denied the use of Tiljander upside-down.
I think this is also a useful question. Did Mann use the Tiljander proxy upside-down?
Regardless of a debatable proxy issue, people can’t seem to admit that the proxy is used upside-down.
Steven Mosher,
I fear the issue is a bit more complicated than that. But before discussing the complications, it might be helpful to try this experiment. I’ll make these comments:
Mann made a mistake; Mcintyre found it; Mann fixed the mistake without crediting Steve; unless proven otherwise, the mistake was .5C for the SH over a period of time.
Now, let’s see what will be the practical consequence of this. People should stop to ask the question, now that one person (i.e. me) made the claims you think no one has.
Perhaps, by making the claims, I do not belong to what is referred as “person” anymore.
Perhaps also, now that the claims have been made, the questioning will lead to a never ending reminder, along the lines of “well, you already admitted that such and such”, in about every future thread in about any popular climate blogs.
Perhaps, finally, this will replace the usual “yes, but Climategate”, or “yes, but RC moderation”?
Sorry: “people”, not “person”.
MikeN #141 — Mann08’s authors did not explicitly deny that they used certain Tiljander proxies upside-down — although that would be the plain meaning of their words. Mann08’s champions delight in moving the conversation to a “What is the meaning of the word ‘is’?” exercise.
While cumbersome, it is useful to specify exactly what is meant by “upside-down,” “inverted,” and like terms. I have done so in a comment at Arthur Smith’s post on the subject of Tiljander.
[…] that Gavin’s arguments didn’t make any sense, a position summarized by Lucia on June 18, 2010 as follows: So let’s go back to Gavin’s closing complaint: Thus what we have is not scientists refusing […]
In the body of this C-a-s post, Gavin Schmidt opined on a comment I had submitted to a prior C-a-s thread.
— begin quote —
One of the pathologies of blog comment threads is the appearance of continual demands that mainstream scientists demand retractions of published work or condemnations of specific scientists for supposed errors or other sins. Most often the issue in question has been discussed dozens of times previously and is usually based either on an irrelevancy, or was acknowledged clearly in the original or subsequent paper or is based on some misperception of the science. [See Mann et al (2008) paper.]… How many times do you need to correct someone’s misperception of a point of science? If they were sincerely looking for truth, the answer would be once. [“continual demands’ link updated]
— end quote —
Recent remarks by Gavin in the RealClimate.org “The Montford Delusion” thread provide significant new information on the significance of the Tiljander proxies to paleotemperature reconstructions in Mann08 (PNAS), and also in Mann09 (Science).
In comment 171, Gavin repeats what he claimed in this post and thread: ” The Tiljander stuff is moot since the Mann et al (2008) paper showed both with and without and found no material difference.”
In comment 414, there is a sea change: “the no-dendro/no-Tiljander sensitivity test is also part of the SI in Mann et al (2009) (figure S8), where it is noted that it doesn’t validate prior to 1500 AD.”
Comment 525: “Since the no-dendro CPS version only validates until 1500 AD (Mann et al (2008) ), it is hardly likely that the no-dendro/no-Tijl CPS version will validate any further back… Note too that while the EIV no-dendro version does validate to 1000 AD, the no-dendro/no-Tijl only works going back to 1500 AD (Mann et al, 2009, SI).
In Comment 529, Nicholas Nierenberg remarks, “Under either method (CPS or EIV) it is not possible to get a validated reconstruction to before 1500 without the use of tree rings, or the Tijlander sediments.” Gavin responds, “That appears to be the case with the Mann et al 2008 network.”
My emphasis, in all cases.
Without the (incorrect) calibration and use of the (uncalibratable) Tiljander proxies, Gavin has now allowed that no-treering reconstructions in Mann08 and Mann09 fail validation prior to 1500. In other words, the oft-cited twice-revised, non-peer-reviewed Fig. S8a that shows no-treering-reconstructions from 400 AD through 1995 is only valid in a 350-year interval (1500 to 1849) in the absence of the Tiljander proxies.
This makes it difficult to support the notion that the use of the Tiljander proxies in the paleotemperature reconstructions by the Mann research group “doesn’t matter.” Until now, that has been the central claim of pro-AGW Consensus scientists and advocates. I responded to the “I don’t know, and it doesn’t matter” position in this thread’s Comment #114; those remarks stand.
This topic is discussed more comprehensively by Steve McIntyre at the ClimateAudit post “The No-Dendro Illusion“.
AMac, the problem is that it isn’t correct to evaluate Mann 2008 in a form that excludes both the Bristlecone Pines AND the Tiljander proxies. Because if you do then the paper is not correct, and we all know and must acknowledge that the paper is correct. It is correct for two main reasons, first because it IS getting hotter all the time and therefore the result is RIGHT regardless of the data or methods, and secondly because it was written by Michael Mann, who is never wrong (unless it “doesn’t matter”).
Therefore your protestations are pointless, the paper MUST be right and it cannot be gainsaid.
Well Keith you might note that there has been movement on the whole tiljander episode which Gavin declared closed.
Apparently, according to gavin, the deletion matters.
Comments drawing attention to this are being blocked at RC. Supporters ( arthur smith for example) have also closed relevant threads
Most of the climate scientists participating in these blogs are doing so to mold public opinion, not to advance climate science. They are (mostly) not interested in the opinions of skeptics and wish they would go away. Climate scientists are insulted that their authority is challenged. Climate scientists don’t see any scientific value in the skeptics poking holes in climate science papers/theories. Climate scientists do not consider skeptics worthy adversaries.
Skeptics, on the other hand, really want the climate scientists to answer their technical questions and feel that these blogs are a means to advance the science.
It seems obvious why it is so difficult to have a constructive dialog between climate scientists and skeptics.
If a climate scientist did agree that it was useful to have a paper reviewed by skeptics in a blog setting, there need to be some rules established a priori. Long ago, IBM did quite a bit of work about how to most productively conduct a review of a document/software/design/etc. IIRC, it was called “structured walkthrough”. A moderator is assigned to run the show. The author (in this case, the climate scientist) produces a set of deliverables for the review and commits to the process. The reviewers are selected and commit to the process. A recorder is selected to record the results of the review. Personal pronouns, insults, filibusters, distractions are all forbidden in the review. The set of documents being reviewed should contain all the material necessary to be self explanatory. Reviewers ask questions and the author points out where this is answered in the document. At the end of the review, minutes are produced, action items assigned and, if rework is necessary, the next review may be scheduled. Alternatively, the document may be blessed.
Last but not least, arguing from authority is a well known logical fallacy (i.e. is not persuasive).