Mann at the NAS Panel

This post got deleted in the server crash. I typically post up from written text, but usually do a final edit as I input onto the blog, so the present note will probably differ a little from what I posted up yesterday, but probably not materially.

Mann did not present anything germane that had not already been presented at realclimate or Ammann-Wahl. As a result, in my opinion, we had fully anticipated and dealt with all his points in our presentation the previous day. Certainly, he said nothing that caused me any concern about the validity of our points. Perhaps the most surprising aspect of his presentation was his response to a question about the verification r2 statistic, in which he denied ever calculating the statistic as that would have been "silly and incorrect reasoning". Given that we’d presented specific evidence that he had calculated this statistic, this seemed to me to be an unpromising line of defence for him.

Mann did not attend any of Thursday”s presentations. As I mentioned before, I did not have an opportunity to meet him as he had “moved on” before the Friday morning session even ended. I have reasonable notes on his presentation, but I am not a great note taker and there are definitely gaps in my notes. [Update: Mann PPT here]

His first slide was a figure showing the location of MBH98 proxies on a world map, based on a similar figure in MBH98. He said that “we have come a long way in 10 years”. As an editorial comment, while people often say this, mostly as a means of distancing themselves from MBH98, I’m a little puzzled as to what the exact advances are: what exactly are the advances? Hockey Team studies mostly are types of averages of small subsets of proxies chosen without any reported selection criteria“ where’s the advance even from Bradley and Jones 1993?

Mann then said that the current emphasis was to reconstruct spatiotemporal patterns and then showed a pretty animation from the Mann et al [2000] interactive presentation, which showed world temperature maps from from 1750-1980 based on about half a dozen reconstructed EOFs from 1750 on. (SM: 6 EOFs do generate pretty pictures. However, in the early portions of MBH98 and in MBH99, there is only one reconstructed EOF and thus no reconstructed spatiotemporal pattern. Whether the EOFs are stationary is a big question. The pretty pictures from 1750 on have nothing to do with the controversial periods. I barely paid any attention to this anomation since I knew that it was irrelevant to any issue in dispute. But some observers thought it was very slick.)

While he presented the animation, Mann said the calculation of the NH average was “scientifically the least interesting”, replicating an ennui about NH mean temperature that we’d previously heard from Alley and Hughes. I’m sure that any policy-maker, or even any civilian, on the panel would have wondered at the disconnect between their pronouncements of NH mean temperature (in, say, press releases) and the present ennui. Nobody on the panel questioned this ennui (nor did they for Alley or Hughes).

Mann then said that it was “specious” to say that IPCC was based on the hockey stick. Soon we started to get the full panoply of Mannian vocabulary “silly”‘?, “incorrect”‘?, “completely wrong”‘?, “not legitimate”‘? were soon to follow, plus at least one more "specious". I think that he missed “spurious”‘?, but I could be wrong.

Mann then reported that MBH was the first reconstruction to describe “self-consistent errors”‘?, a point that we had made in somewhat different terms, as we had described the calculation of confidence intervals in MBH98 as one of its main selling points, contributing to the impression of new levels of statistical accomplishment relative to other multiproxy studies.

Mann went on to say that the “error bars were based on the spectrum of calibration residuals”‘?. My notes show that he then said “that would be completely wrong”, which is a very Mannian turn of phrase, but my notes don’t say what precisely was “completely wrong”. He mentioned that the residuals were “fairly red”‘? and in some cases “significantly red”‘? using a 95% CI. This presumably refers to the discussion of confidence intervals in MBH99. I’ve posted up on this before, reporting that the calculations are incomprehensible (not just to me, but to a time series specialist who asked to look at the matter, and also, as reported to the NAS panel, incomprehensible to von Storch.) MBH99 contains no statistical reference for their confidence interval calculations. I would be surprised if any reviewer of MBH99, either for GRL or for IPCC TAR, understood what he meant and the matter has accordingly been glossed over so far. Anyway no one on the panel asked what Mann to explain this methodology or provide a reference, which is too bad, because it would be nice to know what he actually did.

Mann then turned to an increasingly frequent talking-point (one raised on this blog a few days ago by Tas). He said that IPCC WG1 did not conclude that late 20th century temperatures were “very likely“ only “likely”‘? i.e. 60-70% confidence. The premise of this observation is that, if IPCC elsewhere made claims that exceeded the WG1 confidence, then the scientists of WG1 could not be held responsible for that. I’m not sure that this is correct, but that’s not the issue that interests me. My question is whether WG1 could even claim that Mannian confidence intervals were "likely" – for example, MBH99 confidence intervals were calculated using calibration residuals (using an overfitted methodology) , while the confidence intervals based on verificaiton residuals would presumably be larger (since the verification r2 is directly related to standard error in the residuals). We had already drawn the panel’s attention specifically to this point, but no one on the panel asked Mann about this.

Mann showed the Wiki spaghetti graph. He observed that Esper and Moberg were saying almost opposite things about centennial results. No one on the panel followed up to inquire what this inconsistency between Esper and Moberg at centennial scale meant about suggestions that the spaghetti graph demonstrated some sort of broad consistency. Mann pointed out that Oerlemanns’ results from glaciers suggested a less cold LIA than some of the other spaghetti graphs (supporting the MBH low-amplitude reconstruction.)

Mann said that the Wiki results demonstrated that the HS was not an artifact of tree ring network. Cuffey observed that there was some substantial sharing among networks. Mann replied that Moberg doesn’t share. (This is not strictly true, as there is overlap between Moberg and, for example, Mann and Jones or Crowley.) However, Moberg is relatively independent. (SM: Moberg undeservedly received relatively little criticism. Moberg contains no explicit criteria for proxy selection and is based on a tiny sample of 11 proxies, not all of which are well-chosen. As I’ve posted elsewhere, if you apple-pick a small subset, instead of cherry-pick, you can get a high MWP from the proxy population.)

One of the panellists asked Mann what was the reconstruction tolerance in 1000? Mann said that the scatter is 0.4 deg; “assume”‘? that the results are independent; thus, the tolerance had to be 0.4/sqrt (df) i.e. smaller than 0,.4 deg C for the NH average. Mann was asked: don’t you have to consider error bars in the reconstructions? Mann: only one that has them is Esper (SM: I don’t understand this comment and my note here may be inaccurate). Mann said that the jackknife uncertainty was les than 0.4 deg C.

Cuffey noted that the reconstructions were mostly based on tree rings except Moberg, and wondered again about 20th century divergence.

Mann presented a graphic showing reconstructions from forcing. He pointed out that the von Storch results were an outlier and said that he would recommend leaving out the VS simulation.

Applying a talking-point recently used by Bradley, Mann said that they were extremely aware of the uncertainties in MBH99 – that’s why they used the word in the title. He then showed a slide with the title of MBH99 – which included the word “Uncertainties”‘?. He said that they had emphasized the uncertainties of MBH99 all along, implying that, if others did not, then MBH could harly be blamed. As an editorial note here, I would merely observe that the press release that was issued for MBH99 was hardly a model of caution. (In business, you are responsible for promotional language in press releases, even if more cautious language is used in a prospectus.) The original MBH99 press release, which was widely disseminated (e.g. by AGU), said:

1998 was warmest year of millennium, climate researchers report
AMHERST MA — Researchers at the Universities of Massachusetts and Arizona who study global warming have released a report strongly suggesting that the 1990s were the warmest decade of the millennium, with 1998 the warmest year so far”

"Temperatures in the latter half of the 20th century were unprecedented," said Bradley.

The latest reconstruction supports earlier theories that temperatures in medieval times were relatively warm, but "even the warmer intervals in the reconstruction pale in comparison with mid-to-late 20th-century temperatures," said Hughes.

Read in its entirety, MBH99 used their confidence interval calculations to get to the result that 1998 was the warmest year of the millennium. They calculated 2-sigma error bars from reconstructions (the error bars being incorrectly calculated in my opinion) and then observed that 1998 was above the level of any prior year – thus the conclusion that it was warmest year. (Note that there was no comparison to proxies for 1998, as the proxies had not been brought up to date.)

Mann then said (perhaps in reply to a query about bristlecones – my notes are unclear) that the western US was important to the EOF1; it was a “sweet spot”‘? for estimating NH mean. No one on the panel asked for a further explanation of this. I checked this and was unable to confirm this claim; indeed, my calculations show the opposite. 5 of 6 EOF1 coefficients for the 6 gridcells from 112.5 to 122.5 W and 37.5-42.5N are less than the median (which includes the California bristlecone/foxtail sites) and the sixth is barely above the median. A “sweet sport”‘? is at 7.5N; 52.5-67.5E. The lowish weights in this area are observable in the color-coded diagram in MBH98 itself.

Mann then proceeded to showed a new reconstruction graphic (which as I recall was based on 7 series cherry-picked from Mann and Jones, 2003]. It had a somewhat high MWP, but, as always, the MWP levels are just below corresponding modern levels. Turekian asked: “would you sign your name to this? Mann said that he couldn’t decide between this and MBH: I like chocolate and I like mint.

There was some discussion of a mixed temperature/precipitation signal, but my notes are unclear.

Mann said that he was “more than aware”‘? of CO2 fertilization issues. He said that D’Arrigo and Jacoby et al was “remarkably consistent” up to 1800 with the North American tree ring PC1, which was “adjusted to remove CO2.”‘? On the previous day, we had presented a graphic showing that there was no adjustment to MBH98 figures. No one on the panel asked Mann about the adjustment. We had also showed a graphic from Biondi et al [1999] in which the bristlecones up to 1800 were said to be remarkably consistent with Biondi’s Idaho reconstruction, which, unlike D’Arrigo and Jacoby, did not go up in the 20th century (but which was not selected by Mann for comparison.) No one asked why one was chosen and not the other. No one asked about the physical basis for the adjustment – Mann’s adjustment implies that CO2 fertilization at 3000 m kicks in at about 160 ppm and is saturated at about 175 ppm. [This is from memory of some calculations that I did and I’ll check and edit.]

Mann then said that Ammann and Wahl had showed that MM were “without statistical or climatological merit”‘?, were “completely specious, not legitimate” and that results excluding “key proxies”‘?, “completely fails verification.”‘? He must have been going through withdrawal, as by this time, he’d gone about 20 minutes without saying “specious”‘?. However, he made up for this in very short order.

No one on the panel challenged his interpretation of our results. This was frustrating as we had explicitly stated on the previous day that we had NOT presented an alternate reconstruction, but had shown the impact of various alternatives, in particular, the effect of excluding bristlecones or reducing their impact by centered PC calculations. Draw a deep breath and consider for a moment what Mann (and Ammann) are actually saying: an MBH98-type reconstruction without bristlecones is "without statistical or climatological merit". You know what – we agree with that. Except that we ask: if a reconstruction without bristlecones is "without statistical or climatological merit", what does this imply about MBH98-type reconstructions and all the other proxies? It suggests to me that either the reconstruction method is no good or the proxies are no good or both. Of course, we also say that an MBH98-type reconstruction additionally using bristlecones is "without statistical merit" – a conclusion which is not rebutted by Mann observing that the reconstruction without bristlecones is also without statistical merit. We had explicitly raised this issue and also explicitly stated that the issue was not whether the reconstruction without bristlecones passes or fails an RE test, but whether the MBH98 reconstruction passes an r2 test, citing in addition Bürger and Cubasch on the inappropriateness of using an RE test (supposedly reserved for verification) as a means of choosing between models. The panel let Mann’s observations pass and did not ask him about these issues.

Mann went on to say that you “get same answer if you use a full data set”or if you use “correct PC retention”‘?; “if you don’t use PCA, you get the same”‘?; “as long as you use all the data”‘?. He said that the bristlecones were in the PC4, which needed to be kept using “objective selection rules”‘? (Preisendorfer’s Rule N). He said that MM “eliminate key proxy data”‘?. In keeping with realclimate practice, everything is in code words – “bristlecone”‘? is not mentioned in this context; it’s always “key data”‘?. On the previous day, we had explicitly discussed all these issues, noting the inconsistency between MBH claims of robustness to presence/absence of dendroclimatic indicators and the lack of robustness to bristlecones. Again, no one on the panel raised any questions here and Mann forged on.

Christy did ask Mann: “Did you calculate R2?” ‘? Mann’s answer was: “We didn’t calculate it. That would be silly and incorrect reasoning”‘?. Whenever I hear this statement in my mind, the following phrase runs through my mind: "I did not have r2 with that statistic, Miss Lewinsky".

We had discussed the verification r2 issue in considerable depth on the previous day, even showing a graphic in which Mann had shown verification r2 for the AD1820 step. However, no one on the panel challenged Mann either about his claim that they did not calculate the r2 statistic or why it would be “silly and incorrect reasoning”‘? to calculate the r2 statistic – a point which is not only not self-evident, but incorrect. Perhaps the non-statistical panelists were reluctant to step into an area where they were not experts, given Mann’s aggressive and dismissive response to Christy. However, Nychka and Bloomfield, as statisticians, should have stepped here. I’ve pointed out Nychka’s association with Ammann (he is acknowledged in Wahl and Ammann [2006]); Nychka is a decent guy, but he should have made way for an independent statistician.

Cuffey asked Mann about the divergence problem – is it possible that the proxies are nonlinear and at a threshold? Mann responded by showing 3 series with high late 20th century values (probably from Osborn and Briffa, I’m not sure) and said that these showed no threshold, thus this was evidence that we were not yet at a threshold. No one challenged him on whether these were unrepresentative series, picked from a larger population (as of course they were), although cherry picking had been raised as an issue on the previous day.

Cuffey asked: Do you know the temperature a thousand years ago within half degree? Mann said that it was known “within 0.1-0.2 degree on a century scale.”‘? He was far more optimistic about confidence intervals than anyone else.

My notes show that Mann then said that the RE statistic was “favored by most statisticians; that statisticians don’t use r2″‘?. I don’t have notes on the question. Neither Nychka nor any other panelist challenged him on this point, although statisticians (and the panelists) use the r2 statistic all the time.

Roberts observed that the pre-1000 proxies were sparse.

My next notes are sparse. I show Mann as now discussing the RegEM method, saying that the “RegEM method”‘? was “not subjective”‘?; that Rutherford et al [2005] (using RegEM) did what Bürger and Cubasch asked. We’ve had a little discussion on the blog about RegEm, but the panel was not in a position to contest any of this. At some point, Mann said that they had stopped using the MBH98 method more than 5 years ago and were now using RegEM (as Science mentioned). It should be noted that RegEM has nothing to do with tree ring PC calculations – it’s simply an alternative to the multivariate method in which the proxy network is regressed against the temperature PCs. As an editorial note, Rutherford et al [2005] applied RegEM to the exact same network as MBH98, thus with the flawed PC series.

RegEM is a different multivariate method; its statistical properties are unknown in the sense of ability to estimate confidence intervals. I’ve not parsed through this yet, but I’m certain that they use calibration residuals again, if they calculate confidence intervals. I’ve pointed out that Rutherford et al [2005] incorrectly collated the instrumental record into its calculations. It’s interesting that the methodology is so “robust”‘? that it’s insensitive to whether the instrumental record is collated correctly.

My notes show that Mann then said that he calculated the RE and CE statistics; that the r2 statistic was not “good”‘?, “not sensible”‘?. No one challenged him on this. He continued by saying: “I don’t claim to be a statistician”‘?.

In passing, MBH98 did not report CE results either. It fails the CE test, as well as the r2 test as we had pointed out the previous day. No one on the panel asked about this.

My notes shows that Mann once again said that you had to “look at spectrum of unresolved variance”, but I didn’t record the question. Unfortunately no one asked him for a statistical reference for this procedure, as I’d like to see what the procedure is and what the reference says about it.

North concluded the session by saying:”Thanks, Mike”‘?.

So where were we after this? For anyone familiar with our work, Mann didn’t lay a glove on us. I thought that the previous day’s evidence from Alley and Schrag was unhelpful to the Hockey Team, with some surprising admissions. I thought that D’Arrigo’s musings about cherry picking and cherry pie were an image that must surely trouble the panel. The issue of the Divergence Problem grew legs and clearly did trouble the panel. Hegerl was hard to understand, but admitted that confidence intervals for low-correlation recosntructions went from the "floor to the ceiling". Von Storch was severely critical on many counts, especially replication. Our presentation was severe as well.

And yet soemone like Kerr perceived the proceedings differently. He reported that there were two reconstructions that supported Mann (D’Arrigo and Hegerl) and that Mann had moved on from MBH98 methods over 5 years ago.

Who knows what the panel will ultimately report. I doubt that the panel will end up really drawing a line in the sand against the Hockey Team, but, based on the record of the presentations that I saw, I see only downside for the Hockey Team.


  1. Posted Mar 16, 2006 at 8:29 AM | Permalink

    Those who want to see the original article before the crash, including the comments, click here:

    Feel free to use it in any way you want.

    Best wishes, Lubos

  2. Steve McIntyre
    Posted Mar 16, 2006 at 8:35 AM | Permalink

    I wish I’d known an hour ago. I’ve just spent an hour and a half re-doing the post.

  3. Posted Mar 16, 2006 at 8:42 AM | Permalink

    Sorry, Steve. I could have found it 2.5 hours ago but I just did not look at Climate Audit early enough. Your patience is nevertheless admired. But frankly speaking, when I occassionally lose hours of writing – because of internet browser crash; or an error in re-saving an old version of a paper in the office (which happened to me recently), I usually redo the work, too. 🙂 Next time you should ask whether someone has a backup in the cache, and wait for 1 hour. Of course, exactly this thing will never happen to you again.

  4. Doug L
    Posted Mar 16, 2006 at 8:45 AM | Permalink

    According to Dr. Mann, M&M are still “completely specious”. There’s not much emphasis of uncertainty there!

    I have to believe that the panel is going to discredit Dr. Mann, perhaps with a euphemism like “poor marketing” in place of the word “hype”.

    If they go too easy, perhaps that gives Joe Barton a license to ask the unanswered questions.

    agree with #3 [from posting before the crash ]on the embarrassment factor. [something to the effect that questions were likely not asked to avoid unnecessary? embarassment.]

  5. Posted Mar 16, 2006 at 8:51 AM | Permalink

    Some characters above are corrupt because I have Central European character set by default. The correct UTF-8 encoding of the page is here (it’s the same file with a different header):

  6. fFreddy
    Posted Mar 16, 2006 at 9:02 AM | Permalink

    And yet someone like Kerr perceived the proceedings differently. He reported …

    Sorry, who’s he ? And where did he report ?

  7. fFreddy
    Posted Mar 16, 2006 at 9:03 AM | Permalink

    Preview appears to be AWOL …

  8. Posted Mar 16, 2006 at 9:53 AM | Permalink

    Dear fFreddy, Richard Kerr is a staff writer at Science. I agree that the preview function has disappeared from this blog. I am not sure whether it’s Kerr but Science magazine on NAS made a few words here:

  9. sc
    Posted Mar 16, 2006 at 10:15 AM | Permalink

    Re 1 and 5, Lubos thanks for helping but your link is to the M&M post and comments for 13 March and not the original Mann post and comments. Do you have a link to these also?


  10. Posted Mar 16, 2006 at 10:21 AM | Permalink

    Mea Culpa, I totally missed the difference.

  11. fFreddy
    Posted Mar 16, 2006 at 11:05 AM | Permalink

    Re #8, thank you.

  12. Kenneth Blumenfeld
    Posted Mar 16, 2006 at 12:36 PM | Permalink

    Way back in February there were a couple NAS threads. Everybody was getting all worked up about Cuffey, yet now it sounds like he was one of the toughest panelists. Any comments?

  13. JerryB
    Posted Mar 16, 2006 at 1:30 PM | Permalink

    Re #12,


    In comment #4 at Steve mentioned:

    BTW I told North that I withdrew my concern over Cuffey. Cuffey went to the effort on Thursday of identifying me before we presented and re-assuring me that he distinguished between the issue of the validity of the multiproxy studies and the larger issue of GW and AGW and would not let his opinions on the one prevent a proper evaluation of the other. He then proved to be the most lively questioner and a real force on the panel.

  14. fFreddy
    Posted Mar 16, 2006 at 2:29 PM | Permalink

    Re #12, Kenneth Blumenfeld
    Given how tame and reactive this panel appears to have been, "one of the toughest panelists" is hardly a terrific recommendation.

    On another issue:
    When you first posted here, you referred to the arguments between the warmers and the sceptics in terms of jocks arguing in the locker room, or some such. I assumed that you were new to the subject, and not familiar with the issues, so I ignored your rather (snip) tone.
    However, you have now been coming here for a while. I would have thought that, given your apparent confidence in your intellectual and moral superiority, you would have used this time to educate yourself about the issues, and to come to some understanding of why passions tend to run high among the scientifically literate readers here. (snip)

    So, my questions to you :
    1. Do you feel you understand the problems with multi-proxy reconstructions ?
    2. Are there any areas which you would like to see better explained, to help your further understanding ?

    Steve– c’mon fFreddy – be polite.

  15. John Lish
    Posted Mar 16, 2006 at 3:45 PM | Permalink

    Thanks Steve, an interesting perspective on the workings of the NAS panel. A couple of thoughts come to mind: first, it sounds as though the panel was passive throughout the two days and I wouldn’t assume from that impression that the report will be also (the tactic of letting people hang themselves comes to mind). Secondly, as mentioned elsewhere in this blog is the issue of Boehlert’s request and their subsequent interpretation by Ciceroni as terms of reference for the panel.

    It will be interesting to see how the tensions upon this inquiry are resolved. Not just the external pressures of Capital Hill but professional standings as well. Any idea of a timeline re the production of the report?

  16. fFreddy
    Posted Mar 16, 2006 at 4:09 PM | Permalink

    Yes. Sorry.

  17. Steve McIntyre
    Posted Mar 16, 2006 at 4:31 PM | Permalink

    #15. I mostly agree.

    Probably the main reason for the seeming passivity is that they were chosen not to be intimately involved in the field and there’s got to be a learning curve. No matter how smart you are, it’s hard to see the pea move under the thimble. Most of them were coming pretty cold to the detailed issues. I’m sure that they will come up to speed.

    A second reason is probably that they are pretty nice people and probably don’t like direct confrontations. However, being academics, their pens will sharpen up when they get home and I’m sure that there will be no lack of indirect confrontation. I’m saying this analytically, not as a form of criticism.

    I have no idea what they will report. It would be fun if they became a “runaway jury” and actually brought the Hockey Team back to earth, but the probability is that they will report something in line with what Ciccerone wants.

  18. jae
    Posted Mar 16, 2006 at 4:36 PM | Permalink

    There is SO much wrong with the hockey stick stuff that I gotta believe that science will triumph and the NAS Panel will not end up whitewashing the problems. I can’t see how any impartial observer with a basic understanding of science would not be shocked at phrases like, “you have to pick cherries to make cherry pie.” And I’ll bet there are a lot of scientists (and politicians) watching this saga.

  19. Paul
    Posted Mar 16, 2006 at 4:53 PM | Permalink

    You obviously weren’t watching the BBC the other night. The Hockey Stick had centre stage as undeniable evidence that despite what we may think about past climate, we are presently experiencing the highest temperatures, ever.

  20. Steve Sadlov
    Posted Mar 16, 2006 at 5:30 PM | Permalink

    Mann, based on the description given here, strikes me as one heck of a slippery guy.

    Above and beyond the academic debate, I simply would not trust the man.

    I generally reserve these sorts of judgments but in this case, the level of being ethically challenged in the case of this individual is overt. The emperor has no clothes. But is there courage among the orthodoxy to point it out?

  21. Spence_UK
    Posted Mar 16, 2006 at 5:35 PM | Permalink

    Re #19

    I wonder if the BBC licence fee makes a good proxy for historical temperature?

    Sorry, Steve. Off topic again 🙂

    I take it there is no sign of Mann’s presentation on the internet?

  22. Rod
    Posted Mar 16, 2006 at 5:40 PM | Permalink

    Re: 19 – I assume that was the programme fronted by Paul Rose. One thing I was intrigued by and not previosly aware of were the bronze age settlements on Dartmoor. It was stated that it was likely much hotter than today confirmed by the nature of the plant remains. No explanation was offered for this. Localized climate I guess 🙂

  23. James Lane
    Posted Mar 16, 2006 at 6:22 PM | Permalink

    New Scientist has an article on the Hocey Stick debate. Anyone with a subscription want to give us a precis?

  24. Armand MacMurray
    Posted Mar 16, 2006 at 6:39 PM | Permalink

    Re: #15
    IIRC, the panel website estimated about 4 months to produce the report.

  25. Greg F
    Posted Mar 16, 2006 at 7:08 PM | Permalink

    I couldn’t help but notice some interesting parallels between the NAS panel hearing Steve described and a court case I was involved in some years ago. As a process the two are very similar. The purpose of the process is to provide a forum where the evidence can be examined as objectively as is humanly possible.

    For the case I was involved in there was an issue that required me to hire an expert witness to counter the opposition’s expert witness. With all the witnesses, not just the experts, the judge would occasionally ask questions to clarify some points (it wasn’t a jury trial). Of the opposition expert, the judge asked few questions, mostly to clarify a date or location, but nothing of substance in relation to his expertise. The whole time this expert was testifying I was absolutely livid! To put it politely, their expert was full of bovine excrement. His facts didn’t mesh (he got caught lying) and he contradicted himself logically on several occasions. Meanwhile, I am sitting there dying to ask my lawyer why the judge is not taking this guy to the woodshed. My lawyer afterwards reassured me in the same way you were reassured Steve. He told me “the judge is a smart guy, believe me he noticed’. In sharp contrast, when my expert testified, the judge asked a number probing questions, on both the substance and logic of his testimony. When the judge wrote his ruling he referred to my witness as credible and convincing. He cited questions he had asked and elaborated on why he found the answers to be both logical and convincing. His opinion of the oppositions expert was short. He called him “not credible”. No mention of the lie he was caught in or the contradictions in his testimony.

    The NAS panel’s job is not unlike that of a judge. Viewing it this way, being adversarial or embarrassing a witness would serve no purpose. The panel would also run the risk of not being seen as objective. In contrast consider how politicians conduct hearings. The politicians attack dog technique often has the appearance of being partisan. The panels job is to listen and allow each expert make their case. If they do probe a witness it is to find a possible weakness or more detailed understanding of the argument. There would be little point in probing a witness whose argument is lacking to begin with. The panel will insert their opinion with the report much like a judge inserts his opinion with his ruling.

    PS It was not a criminal trial and I am not writing this from a jail cell. I am not a crook! [shakes jowls]

  26. Suggestion Guy
    Posted Mar 16, 2006 at 7:45 PM | Permalink

    “You obviously weren’t watching the BBC the other night. The Hockey Stick had centre stage as undeniable evidence that despite what we may think about past climate, we are presently experiencing the highest temperatures, ever.”

    My first experience with the BBC was their coverage of a lawsuit on which I worked.

    To say the Beeb’s coverage stunk was an insult to septic tanks covers everywhere. Their first article described, among other things, four motions. It got, not only the mechanisms, but also most of the substance, completely wrong on all four. Incredibly consistent, at least.

    In fact, it really got the subject of the entire suit wrong, blending it with a semi-related political issue involving one of the parties. Which actually favored our client, but it was just ridiculous.

    I thought maybe this was isolated garbage. But I’ve seen it repeated on several other legal matters on which I’ve worked.

    Overall, in terms of accuracy, I’d put the BBC below your average U.S. junior high school weekly. All sorts of broad-based generalizations, lots of melodrama on substantively boring issues and a simply horrible understanding of anything that’s the slightest bit complex.

  27. Terry
    Posted Mar 16, 2006 at 8:53 PM | Permalink

    Mann then said that it was “specious” to say that IPCC was based on the hockey stick.

    This can’t be true. The IPCC prints the graph and discusses it, but it isn’t based on it?

    Are you sure he didn’t say that the IPCC wasn’t based SOLELY on the hockeystick or something like that?

    I just can’t believe he would say something so obviously false.

  28. James Lane
    Posted Mar 16, 2006 at 9:18 PM | Permalink

    OK, I’ve read the New Scientist article (it’s in the current print edition).

    It’s pretty much what you’d expect from NS. It starts and concludes with the assertion that the HS debate is a “sideshow” because other evidence for AGW is incontrovertable.

    Discussion of the HS itself is pretty superficial, and recycles the usual talking points. M&M’s work consists of “obscure” statistical arguments. Von Storch and Huybers concluded that the statistical problems in MBH “don’t matter”.

    Whal & Ammann deliver the death blow: “They found that the reason for the kink M&M graph was nothing to do with their alternative statistical method; instead, it was because they had left out certain proxies, in particular tree-ring studies based on bristlecone pines in the south west of the US”.

    [Wow, just as well A&W “found” that out. Otherwise we never would have known.]

    Then we’re told about the bristlecone growth spurt “at the end of the 19th century” and that Mann corrected for it.* Anyway, replicability is what science is all about, hence the spaghetti graph.

    The conculsion is basically “nothing to see here, move on folks”, although it ends with an observation from Briffa that if the world really was warmer 1000 years ago it would suggest even greater climate sensitivity to forcings: “Greater past variations imply greater future climate change”. I don’t recall seeing that twist before.

    There are some interesting quotes from Jacoby, Gavin Schmidt, Wally Broecker and Briffa, all of whom appeard to have been interviewed for the article.

    *BTW Steve, you promised ages ago to write something about Mann’s “correction” for Bristlecone fertilisation in MBH99.

  29. Posted Mar 16, 2006 at 9:24 PM | Permalink

    Claiming that any of M&M’s arguments are based upon “obscure statistical arguments” is a load of bunk.

    My understanding of statistics is limited to knowing how to calculate a mean and standard deviation, yet I can understand all but the most technical aspects of what they say. How hard is it to understand that any algorithm which gives a meaningful result if fed random numbers has serious issues? I don’t care how complex the mathematics is, something is wrong.

    Their demonstration of the lack of robustness to the presence or absense of certain proxies are also unrelated to anything obscure and statistical. It’s just common sense. Have these people no shame?

  30. Paul
    Posted Mar 16, 2006 at 9:59 PM | Permalink


    They’ve all “moved on”! Didn’t you know that? 😉

  31. Kenneth Blumenfeld
    Posted Mar 17, 2006 at 1:50 AM | Permalink


    Thanks, Jerry B, I missed that.

    #14: Hi fFreddy. Wow, you got the “(snip)” three times! I sure wish I could see what you said. Shucks.

    In answer to your questions:
    1) Did you mean on a scale of 1-10? I’d give it about an 8. I am really much better with small series and GEV stats than with these big messy sets. If I were a dendro guy, I would have lost at least a few key chronologies by now, and Steve would be after me and everybody here would think I was conspiring to influence policy and I would have to spend the rest of my career trying to convince people that I am actually *totally disorganized* rather than dishonest. I would probably be very depressed.
    2) Thanks for asking. I did ask a few days ago how tropospheric phenomena, like thunderstorms, can heat the upper-atmosphere through convection even though the bouyant energy required to release the latent heat as sensible heat does not make it past the tropopause (which is not the upper atmosphere). Steve took a crack at it, but I never followed up to ask what he meant by “upper atmosphere,” and other explanations were not directly confronting convection, or the transfer of heat through adiabatic processes. So that question lingers, even though it is off-topic. Can you enlighten me?

  32. Rod
    Posted Mar 17, 2006 at 4:10 AM | Permalink

    re: #28 It might be worth downloading the New Scientist podcast which should be available sometime today – to see if there are any interviews with the Hockey Team. BTW did you read the editorial?

  33. fFreddy
    Posted Mar 17, 2006 at 6:09 AM | Permalink

    Re #31, Kenneth Blumenfeld

    Ref 1) The problems with the reconstructions are dodgy maths and dodgy data. From your answer, I assume you are happy with the maths issues. Regarding the data issues, there is a third option: if you have lost the data, then don’t publish work based on it. If you only find out after publishing that you have lost the data, then withdraw the publication until you can go and regenerate the data.
    You may say that’s all very well in theory, but it’s not how the real world works. Well, maybe so for small issues. But any scientist in this field must be aware of how the political activists have been using their work. It is less than satisfactory for (supposed) scientists to act with anything less than the highest standards in this instance.
    I think that one of the most annoying things in Steve’s report of the NAS panel is the way that all the other presenters (except Mann), when put on the spot, said that they did not believe in the supposed accuracy of the millenial reconstructions. These people were from the AGW-friendly end of the spectrum. So where the hell were they when the activists were screaming about a complete scientifc consensus that the 1990s were the warmest decade of the millenium, the debate is over for rational people, etc. ad nauseam ?
    Scientists hold a special position of trust in our society, and quite rightly so. But that is a two-way obligation, and these people have failed to hold up their end.

    Hmph. /Rant off.

    Ref 2) – sorry, beyond my competence. My suggestion in the other thread about sprites was only semi-serious : although they are a major energy transfer across the tropopause, I have no idea if they are of the right order of magnitude to be relevant.

  34. fFreddy
    Posted Mar 17, 2006 at 7:31 AM | Permalink

    Ref #19, #22
    I dunno, I found myself strangely cheered by that program.
    I think the first half was the best presentation I have seen (on the BBC) of past climate variability. The Dartmoor Bronze Age site (new to me too, Rod) was shown as good evidence of a period 3,500 years ago when it was warmer than today.
    (Peter Hearnden, isn’t that your neck of the woods ? Are you familiar with that site ?)
    Similarly, looking at detailed pictures of the Thames freezing in the Little Ice Age, the presenter was pointing out how much it looked like what he was used to seeing in Greenland.
    Then, as you say, it brought up the hockey stick and rapidly spun off into that ridiculous million monkeys thing.
    It just seemed to me that, if you were coming to this with no previous knowledge of the subject, the disconnect between the first half of the program and the hockey stick was so great that it would have to raise questions in your mind.
    Or maybe I’m an optimist.

  35. John Lish
    Posted Mar 17, 2006 at 7:51 AM | Permalink

    #34 – it was a tad incongruous though fFreddy – after all Paul Rose was selling himself as a skeptic yet did he apply one ounce of skepticism towards the Hockey Stick? I agree that the images in the programme were blindingly at odds with the flatness of the Hockey Stick yet Rose accepted the shaft without objection. As for the metaphor with golf balls…

  36. kim
    Posted Mar 17, 2006 at 9:09 AM | Permalink

    That little soupcon Briffa twists into the mix, as James L. points out, may be the coming meme: that the balance is so delicate that even a little anthropogenic forcing is magnified and potentially catastrophic. Humans’ vast need and ability to assume guilt is on display. Hide and watch like the bird sitting in his woven feedback camera and scream like a cat.

  37. Peter Hearnden
    Posted Mar 17, 2006 at 9:24 AM | Permalink

    Re #34, I’m familiar with Dartmoors bronze age (?) hut circles – they’re everywhere here (as are, for that matter, flint artifacts). I do think they say’s more about the inhospitability of lower down than it does warmth (though I suspect it was warm, the Dartmoor tops, even if a degree or two warmer than now, aren’t going to be exactly nice (or even Nice) in the winter) becuase it would HAVE to be warmer lower down. Thick forest at low levels was the reason life up top became attractive? Or perhaps the best bits lower down had been taken and people HAD to move up? I don’t know, but, again, it HAD to be warmer lower down, so ‘up top’ isn’t going to be a first choice.

    Re the rest I’m running the experiment (and very interesting it is too), but, clearly, not running it makes people far more expert about it than actually watching it all happen…

    Re golf balls & Paul Rose, well he didn’t go around as if he knew better than the experts – silly him, just how respectful and polite can you get!

  38. Armand MacMurray
    Posted Mar 17, 2006 at 5:39 PM | Permalink

    From the NYT:

    WASHINGTON, March 17 “¢’‚¬? Representative Sherwood L. Boehlert of New York, a centrist Republican who became a national science advocate while looking out for his upstate district, announced today that he would not seek re-election…

    So, he will give up his chairmanship of the House Science Committee at the end of the year, about 4 months after the panel report, if it comes out on schedule.

  39. Hans Erren
    Posted Mar 17, 2006 at 5:59 PM | Permalink

    So Michael Maan doesn’t show up until the last moment for a meeting organised to discuss one of his publications, where people from outside the us have been flown in.

    He doesn’t attend other presentations, he gives his own presentation and disappears without a debate…

    Say no more.

  40. Doug L
    Posted Mar 17, 2006 at 6:07 PM | Permalink

    RealClimate’s apparent reaction to NAS panel:

    The debunking of a wild theory on global warming!

    A press release announced that a Russian scientist had submitted the theory to an obscure non peer reviewed journal. The idea is that the 1908 Tunguska meteor event in Siberia may be the cause of Global Warming.

    Part of a Lubos comment:

    “The author of the Tunguska theory, Vladimir Shaidurov, is the winner of the most prestigious scientific award in Russia for 2004, the State Prize, and he is the director of the Computer Modelling Institute of the Russian Academy of Sciences “

  41. Peter Hartley
    Posted Mar 17, 2006 at 6:11 PM | Permalink

    From #28: “if the world really was warmer 1000 years ago it would suggest even greater climate sensitivity to forcings”

    It would not suggest greater sensitivity to CO2 forcing, however, but just the opposite. The concentration of CO2 in the atmosphere over this period follows a “hockey stick” shape. If average temperature does not, that implies that CO2 forcing cannot be very large. It also implies that natural changes are large relative to what we have seen in the 20th century. This implies in turn that it will take much larger changes before we can conclude unambiguosuly that average temperatures are definitely anthropogenic in origin. I don’t think any “spin” can make the death of the Mann hockey stick a positive for the AGW thesis.

  42. Hans Erren
    Posted Mar 17, 2006 at 6:20 PM | Permalink

    re 40:
    The only part that wasn’t censored….

  43. Willis Eschenbach
    Posted Mar 17, 2006 at 6:55 PM | Permalink

    Re: #40, I read the paper about the tunguska theory … the depressing part of the study was, guess what the authors used to show how Tunguska had changed things in the 20th Century?

    For those of you that answered, “the original, never-to-die Hockeystick from MBH98”, go to the head of the class. The Hockey Team may have moved on, but there’s still lot’s of folks out there who haven’t gotten the news. Including, apparently, Vladimir Shaidurov …

    RealClimate missed out on the opportunity to comment on Shaidurov’s use of the Hockey Stick, though. The original post, and 50 different comments, and nobody said a word about the use of the Hockey Stick by Shaidurov to buttress his argument … probably just an oversight on their part, I guess …


  44. Paul Penrose
    Posted Mar 17, 2006 at 7:40 PM | Permalink

    One of the things that people like Peter H. pound on is that it’s wrong to question the work of the “experts” if you yourself are not one of the recognized “experts”. What a bunch of bunk. I’ve seen plenty of smart people make stupid mistakes, and it does not take a genius to find them (the mistakes). In the final analysis the most important thing is to correct the errors so that truth and science moves forward.

  45. Terry
    Posted Mar 17, 2006 at 9:33 PM | Permalink


    Figure 2 in your writeup (page 10 in the PowerPoint presentation) is just devastating. If a result ain’t in the simplest analysis, it probably ain’t there at all.

    This suggests another way to think about the MBH analysis. Perhaps all it is doing is forcing the reconstruction to have an upward slope in the 20th century.

    When you fit the reconstruction to an upward trend in the 20th century, the reconstruction will have an upward trend in the 20th century — duh. The rest of the reconstruction is just garbage tacked on to the beginning of the 20th century trend, and your simple average plot explains why: in the aggregate, with nothing to force it one way or the other, the proxies are just noise.

    Further, MBH probably get their alleged skill only because the proxies have enough persistence that when you pick proxies with a localized trend, they retain some of that trend in nearby windows, so your model appears to have some skill in predicting the nearby trend.


  46. Rod
    Posted Mar 18, 2006 at 2:04 AM | Permalink

    Re: #32 – the New Scientist podcast featured an interview with Fred Pearce only. Pretty much the same as the article.

  47. kim
    Posted Mar 18, 2006 at 9:00 AM | Permalink

    Mann has a big problem. He’s the ‘Boy Who Cried Wolf’, and he’s in trouble whether the Wolf shows up or not.

  48. The Knowing One
    Posted Mar 18, 2006 at 1:28 PM | Permalink

    Tunguska is a bit off-topic for this blog, but if anyone is interested, what seems to be a good explanation for it was published by Walter Kundt in Current Science [2001].

    Very briefly, there was a large (natural) leak of natural gas. The gas rose up until it reached equilibrium density with the atmosphere, then it was blown horizontally downwind—into a thunder storm. The storm’s electricity ignited the gas. The flame’s path followed the path of the gas: first horizontally, then vertically, to the source of the leak. Then BANG.

    Kundt describes how this explanation fits virtually all details that are known about Tunguska. Yet not everyone has accepted the explanation, seemingly because it is not as exciting as most prior speculations.

  49. Doug L
    Posted Mar 18, 2006 at 2:24 PM | Permalink

    This is also OT but breaking news on a scientific controversy and perhaps even relevent. The sighting of the Ivory Billed Woodpecker which was caught on film is now under dispute .

    From a National Geographic article:

    “For their part, the original team that identified the bird as an ivory-bill dismisses the challenge to their finding in a response also published in tomorrow’s Science”


    “But David Sibley says the burden of proof is on the Cornell-led team. It’s up to them, he says, to show that the species is not a pileated woodpecker. ”

    Now if only Science and others would apply that standard to AGW! 🙂

  50. Neil Fisher
    Posted Mar 20, 2006 at 3:29 PM | Permalink

    Re: New Scientist article. I’ve read the print version. Coupla things. They note that Steve works in the “oil industry”. They suggest that UNIPCC TAR supports Manns work, but fail to acknowledge that Mann is the lead author. No mention of the cutoff of the proxy data that doesn’t fit (A&W). No mention of finding a hockey stick using red noise as input to the Mann method.

    But despite all that, you have to give them this: they published something on it, which is more than most. Pity it’s full of mistakes.

  51. Mark
    Posted Mar 20, 2006 at 4:32 PM | Permalink

    I had a subscription, but cancelled it due to continued… well, if you live in the US and subscribe to NS, you’ll understand. Anyway, I think the subscription ran out last week so I can no longer access the article to verify comments in here.

    However, that they would note Steve works “in the oil industry” is no surprise. Late last year, they had an article on the religious supression of science, primarily targeted at the Bush administration. The editorial made a few great points then rambled into the GW/Kyoto affair. I’m not sure what the latter has to do with religion, but it was apparent there was an ideological axe to grind.


  52. Posted Jan 28, 2008 at 8:29 AM | Permalink

    Mann then said (perhaps in reply to a query about bristlecones – my notes are unclear) that the western US was important to the EOF1; it was a “sweet spot”’? for estimating NH mean. No one on the panel asked for a further explanation of this. I checked this and was unable to confirm this claim; indeed, my calculations show the opposite. 5 of 6 EOF1 coefficients for the 6 gridcells from 112.5 to 122.5 W and 37.5-42.5N are less than the median (which includes the California bristlecone/foxtail sites) and the sixth is barely above the median. A “sweet sport”’? is at 7.5N; 52.5-67.5E. The lowish weights in this area are observable in the color-coded diagram in MBH98 itself.

    There is also interesting cold spot at Western Greenland (Mann’s grid point 969, 72.5 N 27.5 W), a place that responds negatively to the warming trend (described by TPC1). Can’t find data for that grid point from HadCRUT3. I’d like to find recent data for that grid, as you note

    Whether the EOFs are stationary is a big question.

    (Of course, any nonstationarity is likely to be a response to some kind of recent anthropogenic forcing)

  53. Skiphil
    Posted Mar 18, 2014 at 10:17 AM | Permalink

    Might be interesting for someone with the requisite expertise to compare what is required for physicists to consider a “5 Sigma” level of confirmation vs. what prevails in climate science. I was wondering about this comparison after watching this brief video of a leading astrophysicist getting what seems to be a high level of empirical confirmation of his mathematical exposition of the “inflationary” theory of the “Big Bang” ….. great short video anyway, on the joys of science:

    • Posted Mar 18, 2014 at 2:27 PM | Permalink

      Yes, I was struck by the question Andrei Linde says he has asked himself all these years: What if I am tricked?. Would it have ever been in Mike’s Nature to do the same? 🙂

      • Skiphil
        Posted Mar 18, 2014 at 3:04 PM | Permalink

        yes, “What if I am tricked” ….. matters greatly to Andrei Linde but not to Mannian CliSci

        btw, I did not know WUWT already had a thread on this or I would have done a h/t….. I actually found the video when searching on more news about the announcement…..

2 Trackbacks

  1. By The Mann Report « Climate Audit on Feb 3, 2010 at 4:48 PM

    […] the panelists sat there like bumps on a log. My contemporary post on Mann’s presentation is here and noted: Christy did ask Mann: “Did you calculate R2?” ‘? Mann’s answer was: “We […]

  2. […] is the passage from The Hockey Stick Illusion and McIntyre’s blog: He [McIntyre] explained to the panel how Mann had reported in MBH98 that he had calculated the R2 […]

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