Ammann at AGU: If You Had One Question..

Ammann made a presentation at the same AGU session as me, spending a considerable amount of time criticizing us — though with nothing new to say that we haven’t already rebutted here and in print. There was time for one question (AGU is fanatical about schedules) and I was recognized. So here’s my question to you: if you had one question to ask Mann or Ammann on such an occasion, what would you ask? Think about it before reading my choice. (Interestingly. Ross, under different circumstances, independently made the same suggestion).

Here was my choice: what is the cross-validation R2 statistic for the 15th century MBH98 reconstruction? It’s not that I don’t know the answer. The answer is ZERO (well, 0.02). I just wanted him to say it out loud, in front of his professional colleagues.

You’re going to have to wait to see what his answer was, because I’m first going to take you through the history of previous requests for this information (or equivalent information from which it can be obtained i.e. the residual series for the 15th century reconstruction.) When I started writing this post, I thought that this would be a short detour, but the detour has taken on a life of its own, as the request has made to Mann himself directly, to N.S.F., through Climatic Change in 2004 in connection with reviewing a submission by MBH, to Nature, by Natuurwetenschap & Techniek to Mann, by the House Energy and Commerce Committee to Mann, by Climatic Change in 2005 to Ammann. It’s an interesting chronology and raises many interesting questions about journal practices. This history is in parallel to requests for source code, but it raises many of the same issues in even sharper focus as the (weak) arguments for non-disclosure of source code cannot be extended to the withholding of cross-validation statistics and/or the residual series from which they are generated.

I also invited Ammann out to lunch at AGU after the session and I’m going to eventually describe an interesting offer that I made to him after I get through the R2 request (and its seeming outcome).

Mann and N.S.F. – 2003
I’d lost track of how long I’ve been attempting the Hockey Team to produce residual series from which the cross-validation statistics could be calculated and just how many evasions have taken place. So before getting to Ammann’s most recent evasion, you’ll have to indulge a review of the bidding. I’ll move it along a little faster after today’s account of 2003 events.

We began our request for residual series as early as December 2003. These requests were distinct from concurrent requests for source code and other issues, which were then in controversy. So to put the residual requests in context, I also have to note the source code debate. The next stages won’t be as prolix.

Mann had claimed remarkable statistical “skill” for his reconstruction — claims that were not made for other multiproxy reconstructions and which undoubtedly led to the wide acceptance of Mann’s work. The IPCC even said

Averaging the reconstructed temperature patterns over the far more data-rich Northern Hemisphere half of the global domain, they [MBH98] estimated the Northern Hemisphere mean temperature back to AD 1400, a reconstruction which had significant skill in independent cross-validation tests. Self-consistent estimates were also made of the uncertainties. [my bold]

Despite the boldness of these claims, we made no attempt in our 2003 paper to test these claims. One of the reasons was simply that the focus of our 2003 paper was fairly narrow. First, we wanted to demonstrate the remarkable lack of data quality control in MBH98, including the use of obsolete data. Most of the issues raised there still remain unanswered, such as, for example, the amusing use of precipitation statistics from Paris, France in the New England gridcell (an issue dodged in the Corrigendum).

Second, we wanted to show the problems in the principal component calculations. At the time, we were unable to identify exactly what was wrong with the PC series in the data set at Mann’s FTP site — other than there was obviously something seriously wrong. We had identified the problem by simply trying to verify the PC calculations. We had re-collated hundreds of tree ring series from WDCP and made fresh PC calculations and compared the explained variance of the MBH series to the explained variance of the fresh calculations — showing that the MBH explained variance was much lower. Later we were able to determine that there were three different problems: they used a previously undisclosed stepwise method and in the archived data set, values from different steps were spliced — a nonsensical procedure (the stepwise procedure itself was not initially reported and is by no means a common, proven or well-understood statistical procedure); in addition to the incorrect splicing, the series were collated incorrectly, which we’d noticed from the bizarre identify of 1980 values; finally, they used the bizarre and undisclosed short-segment centering. Interestingly, the illustration in our 2003 article was actually from the Australia network (where stepwise issues were not a factor), and not the North American network about which so much has been written. Mann claimed that the splicing occurred only in the collation archived at his FRP site and not in MBH98 calculations themselves. He blamed this incorrect collation on our supposed request for an Excel spreadsheet (which we had not requested) and claimed that the incorrect collation had been prepared especially for us (it had not, as it was dated much earlier on the FTP site; Mann deleted the file and this date evidence). The source code archived last summer indicates that MBH98 itself probably did not use incorrectly collated or spliced PC series; however, the use of incorrectly centered series is definitely proven.

Thirdly, in our 2003 article, we wanted to show the impact of freshly calculated PC series and non-obsolete data (and, as it turned out, non-manipulated data) on the final NH temperature reconstruction. Now we had thought that we had made it completely clear that we had not offered an “alternative” reconstruction.

Without endorsing the MBH98 methodology or choice of source data, we were able to apply the MBH98 methodology to a database with improved quality control and found that their own method, carefully applied to their own intended source data, yielded a Northern Hemisphere temperature index in which the late 20th century is unexceptional compared to the preceding centuries, displaying neither unusually high mean values nor variability. More generally, the extent of errors and defects in the MBH98 data means that the indexes computed from it are unreliable and cannot be used for comparisons between the current climate and that of past centuries, including claims like “temperatures in the latter half of the 20th century were unprecedented,” and “even the warmer intervals in the reconstruction pale in comparison with mid-to-late 20th-century temperatures” (see press release accompanying Mann et al 1999) or that the 1990s was “likely the warmest decade” and 1998 the “warmest year” of the millennium (IPCC 2001).

Since we did not present an alternative reconstruction, but simply an implementation with freshly calculated PC series and updated data versions, it did not occur to us that cross-validation statistics were relevant to what was essentially an argument demonstrating that MBH98 results were not robust. In retrospect, BàƒÆ’à‚⻲ger and Cubasch [2005], who refer approvingly to our work, have substantially expanded this approach. They point out that there are many methodological choices available within an MBH98-type algorithm (they describe them as “flavours”, identifying 64 different ones), with results differing between “flavours”. In fact, the list of methodological issues canvassed by BàƒÆ’à‚⻲ger and Cubasch does not include most of the methodological issues discussed in MM03, and the number of flavours increases exponentially. BàƒÆ’à‚⻲ger and Cubasch make the neat point that, if the RE statistic is used to choose between “flavours”, it cannot also be used as cross-validation. It’s a neat argument that should be kept in mind as we review the subsequent history.

After our first E&E article in October 2003, Mann immediately made public through David Appell the claims that we’d used the “wrong data”. The David Appell website no longer exists, but the claims are archived here. Suddenly at Mann’s FTP site there materialized a previously private data directory that differed from the data set at his FTP site to which we’d previously been directed and which Rutherford had been unaware. Mann claimed that we’d used the “wrong data”. (For the lugubrious early story, the correspondence with Mann prior to MM03 is here see and our contemporary assessment of this dispute is here

Concurrently, Mann made a less absurd response on the internet here. He claimed that we had incorrectly implemented his algorithm (not mentioning that he’d refused to respond to previous requests for a more adequate methodological description.)

This article also discusses cross-validation statistics (and I’ll return to this shortly and get this narrative off the ground a little better). But our first reaction was not on the cross-validation front, but simply to try to figure out what Mann was doing based on these comments. For example, he said that our emulation was flawed because we didn’t use 159 series — now 159 series was never mentioned anywhere in MBH98 or elsewhere. So we asked him for a listing of the 159 series and concurrently we asked for a copy of the source code, pointing out in quite reasonable and civil terms that we had no interest in pointless controversy over methodological details and this seemed like an effective way for us to reconcile any such methodological discrepancies. We made the requests here , reiterated here . Mann refused.

Not having any luck with Mann, we tried Bradley here, also without success

Having no luck with either, we tried with NSF on source code here and filed a Materials Complaint with Nature on a variety of questions. (We never did get any answers on these matters from Nature. We later re-iterated the request to Nature in August 2004, more on which tomorrow.

The source code dispute has received a lot of public attention. N.S.F. refused immediately on the basis that it was Mann’s personal property; Nature also refused. Mann told the Wall Street Journal that he would not be “intimidated” into disclosing his algorithm, but later produced source code for the House Energy and Commerce Committee that was inoperable with any existing data sets. Again this story has been discussed elsewhere.

Anyway, in December 2003, we turned our attention to the matter of the residuals, as a result of certain claims made in Mann’s Internet response here , where MBH countered that their reconstruction had significant skill (which they measured by an RE statistic), while “ours” didn’t, as follows:

MBH98 employed the standard statistical tool of cross-validation to verify the skill of their reconstructions. MM describe no such tests. Since increasingly sparse networks are used progressively farther back in time, a series of cross-validation experiments have to be performed to estimate the skill for different time intervals. For the AD 1400-1500 period, this involves, in MBH98, performing the reconstruction over the interval 1400-1901 based on calibration against the instrumental record over the interval 1902-1980, using the specific network of proxy indicators available for the AD 1400-1500 period. The reconstruction is then independently compared against the instrumental record over the interval (1854-1901) not used for calibration. The skill can be described (see MBH98) by a ‘Reduction of Error’ statistic (RE), which is bounded by negative infinity and positive one, with substantially positive numbers indicative of predictive skill. The mean expected value for a random estimate is -1.

For the reconstruction with the data eliminated in a manner similar to that implicit in the MM approach, the RE score (-6.6) is far worse than even a typical random estimate, and such a result would have been discarded as unreliable based on the cross-validation protocol used by MBH98. The anomalous warm values during the 15th century are the artifact of an entirely unreliable statistical estimate. By contrast, the MBH98 reconstruction indicates an RE of 0.42 for the 1400-1500 interval, indicative of significant predictive skill during that time interval.

This is one of the earliest attributions of an “alternative” reconstruction to us – something that is done both by right-wing commentators and Mannians for different purposes– a somewhat unholy alliance. We had thought that our disclaimer in the text had been very clear that we were not proffering an "alternative" reconstruction. However, for greater certainty, we provided the following additional statement in the FAQ to MM03:

Your graph seems to show that the 15th Century was warmer than today’s climate: is this what you are claiming?

No. We’re saying that Mann et al., based on their methodology and corrected data, cannot claim that the 20th century is warmer than the 15th century — the nuance is a little different. To make a positive claim that the 15th century was warmer than the late 20th century would require an endorsement of both the methodology and the common interpretation of the results which we are neither qualified nor inclined to offer.

You’d have thought that these two statements were pretty clear and we’ve continued to make similar statements. Most recently, after the Wall Street Journal editorial page incorrectly attributed an alternative reconstruction to us, Ross published a letter at the WSJ disassociating ourselves from having made an alternative reconstruction. It’s one thing to have journalists mis-interpret your statements, but it is far more pernicious when academic commentators like Mann or Ammann, who actually know better, nevertheless perpetuate the canard that we have made an “alternative” reconstruction, presumably because it provides a completely diversionary tactic. More on this later.

We started our consideration of verification statistics in December 2003 by a request to Mann for the residual series in the 15th century (and other steps), which had not been archived even at the new FTP directory. (The residual series, aside from being helpful in benchmarking replication, are obviously essential in doing statistical tests and necessary to validate any claims to statistical “skill”.) Now Mann had already refused to provide source code or to identify the 159 series, so I did not actually expect him to provide the residual series, but unless you ask, they can always use that as an excuse. Dan Verardo of NSF (from whom I’d sought assistance on source code was copied. )

Before Mann himself refused (which I expected but I still had to ask), Verardo wrote that Mann was not obligated to provide this information on the grounds that I was “free to [my] analysis of climate data and [Mann] is free to his.” Needless to say, Mann did not send the requested information.

So as early as December 2003, Mann and NSF had refused requests for residual series, necessary for verifying cross-validation statistics. I’ll proceed to discuss subsequent events with Nature, Climatic Change, Natuurwetenschap & Techniek and the House Energy and Commerce Committee with respect to Mann and then Climatic Change and AGU with respect to Ammann. I’ll try to move the segments along a little faster, but no promises. (The downside of blogging is that these notes are not highly edited. )


  1. ET SidViscous
    Posted Jan 9, 2006 at 3:50 PM | Permalink | Reply


    Is there going to be a part two or something. Nothing on Ammann’s answer or this lunch, inquiring minds wnat to know.

  2. John A
    Posted Jan 9, 2006 at 4:07 PM | Permalink | Reply

    Steve watches soap opera thrillers like “24″ and it shows.

  3. Steve McIntyre
    Posted Jan 9, 2006 at 4:19 PM | Permalink | Reply

    Sure, there will be a few more parts. The fabrications back then get under my skin and I go on a bit too much about them, so indulge me a little.

    Nice that you mention 24. Its season premiere is on Jan. 15th. Finally. Hooray.

    Speaking of entertainment, yesterday, I went with my wife and mother (82) to see Good Night and Good Luck – the George Clooney movie about Edward R. Murrow versus McCarthy. What a good movie it was. Clooney deserves a lot of credit for this. Movies about courage are always inspiring and I was glad the movie also recognized the courage of the CBS executives, e.g. Paley, as well as Murrow and Friendly. It’s remarkable how eloquent Murrow’s words were. Additionally, the cultural images were very authentic and reminded me of my childhood – the formality of the attire, the smoking.

    #1, You’ll have to wait for a few more installments to get to the punch-line (or maybe I’ll slip it in along the way.)

  4. ET SidViscous
    Posted Jan 9, 2006 at 4:25 PM | Permalink | Reply

    Ahh I don’t mind waiting. You just didn’t put up a part 1 or something so I had no idea.

    I just figured you got all worked up ala John Belushi on his Weekend Update rants and just we’re freaking out around the house and forgot we were waiting for the punchline.

  5. Ray Soper
    Posted Jan 9, 2006 at 4:26 PM | Permalink | Reply


    re: “The fabrications back then get under my skin and I go on a bit too much about them, so indulge me a little.”

    Don’t worry about it at all. There are new people coming to this site all of the time, and it is useful for them (and the rest of us) to be made aware of some of this history.

    But certainly I (and many others) are looking forward to the unfolding of this intriguing story!

  6. John A
    Posted Jan 9, 2006 at 4:46 PM | Permalink | Reply

    It’s remarkable how eloquent Murrow’s words were. Additionally, the cultural images were very authentic and reminded me of my childhood – the formality of the attire, the smoking.

    As a child, you smoked while wearing a suit? Bizarre!

  7. joshua corning
    Posted Jan 9, 2006 at 4:55 PM | Permalink | Reply

    You’ll have to wait for a few more installments to get to the punch-line (or maybe I’ll slip it in along the way.

    thanks now i can freak out with worry and antisipation…thanks alot steve. :P

    Oh yeah about the Clooney movie…i find it intellectually dishonest…McCarthy was no saint but the movie fails to point out McCarthy’s source of power which was Stalin. Without pictures of starvation and genicide it is hard to put McCarthy’s crusade into context of the fear that spawned it.

    Anyway it is only a movie and it is from hollywood so i shouln’t really expect better.

  8. muirgeo
    Posted Jan 9, 2006 at 8:56 PM | Permalink | Reply

    If I had one question for Dr Amman at the AGU meeting?

    Dr. Ammam, there have been many…er several… one or two persistent critics of the paleoclimatic literature who claim to have found fault with each and every single paper ever written on the subject. Why do you think none of them….err..uh.. either of them….has taken time out of their very busy schedule criticizing to the finest detail the fault in every one else’s work and instead just gathered what they feel are the most reliable existing proxy data and publish their very own multi-proxy peer reviewed paleoclimate study to see what results they get?…Why Dr Amman?

  9. Steve McIntyre
    Posted Jan 9, 2006 at 9:13 PM | Permalink | Reply

    #7: in terms of 20th century villains, I agree that McCarthy was pretty small beer, but he was still a bully and a villain.

    In terms of context, as someone growing up in the 1950s, my recollection is that the fear and hatred of Russia did not derive from starvation or genocide. My recollection is that we usually associated starving with people in India or China, not Russia – “Eat up your food, there’s starving children in India [China]“.

  10. Pat Frank
    Posted Jan 9, 2006 at 9:58 PM | Permalink | Reply

    Mao’s agricultural reforms of the 1950′s killed nearly 40 million people, Steve. Maybe the cultural adage of starving Chinese children referred to that. Stalin’s main murder spree of about 30 million was mostly over by 1938. That rampage would not have been lost on government policy-makers of the 1950′s, however. Maybe in the absence of the WWII diversion, kids of the 1940′s would have been scolded in terms of starving Russian or Ukranian children. Ho Chi Minh was also murdering about 100,000 North Vietnamese in his reforms during the 1950′s, but in view of China, HCM’s murders were probably under the public’s radar.

  11. Steve McIntyre
    Posted Jan 9, 2006 at 10:37 PM | Permalink | Reply

    I was a child in the 1950s so my perspective is limited. But I was aware of things – I remember doing a class speech on potential successors to Stalin, so I was already choosing boring topics. But I don’t remember the Chinese and Russian holocausts (much less Ho Chi Minh) as being issues being used to scare people (and I’m sure that they would have been if the politicians thought that they would scare people.) I’m not sure that people even knew about them in the 1950s. The scaring came from intercontinental missiles and nuclear bombs. At school in Toronto in the late 1950s, we practised evacuations in case of a nuclear attack. That was what was on people’s minds, not inhumanity to peasants in Russia and China. Travel to China was then virtually impossible and knowledge of China was surprisingly sketchy. It’s hard for someone growing up today to appreciate. I suspect that many people would have viewed reports of so many deaths as propaganda. I’m not sure when the size of the killings dawned on people, and it’s funny that I can’t remember, but I suspect that it would be in the 1970s rather than the 50s or 60s.

    I visited Cambodia in 1968 while the Vietnam War was on, travelling to Angkor Wat, which was spectacular. Not surprisingly, there was hardly anybody there at the time. It is an extraordinary puzzle to me how this seemingly quiet nation should have spawned the murderous Pol Pot regime.

  12. Dave Dardinger
    Posted Jan 9, 2006 at 10:54 PM | Permalink | Reply

    re #8,

    George, if you’d have read some of the discussion on various threads here where various warmers have asked the same question of Steve, you’d know that the problem is largely of on there not being many /any proxies which are reliable enough. IOW, when you chuck out the Bristlecone Pines and the other proxies Steve has shown problems with, the remaining proxies either have no statistical validity or they don’t show AGW.

    And anyway, if you really knew the scientific method you’d know that there’s no reason disproving a theory, (or at any rate showing that it’s not been proven), has to or even should be accompanied by a new theory to replace the old one.

  13. John S
    Posted Jan 10, 2006 at 12:03 AM | Permalink | Reply

    If someone is making mud-pies in a pig-sty and an outside observer says “You are making mud-pies in a pig-sty”, it is not usually relevant to state “Let’s see you make better tasting mud-pies in this pig-sty”. Sensible people will stop making mud-pies in the pig-sty.

  14. muirgeo
    Posted Jan 10, 2006 at 12:57 AM | Permalink | Reply

    RE # 12

    So not only have they disproved all the multiproxy paleoclimate studies but they have also shown ALL of the paleoclimate data to be useless. We can also say nothing about present climate since we know the surface data is completely useless because of the urban island heat effect and the satellite data used to be good but now it is also useless….just because. Finally, the future climate is unknowable because the GCM’s used to predict it use the source code GI=GO and thus cannot be relied on. Wow that’s the Triple Crown….climate past, present and future is unknowable. Shoot we can just sweep all the useless evidence under the rug and hope mother nature’s not watching. And that’s what makes you sleep a little better at night Dave? You bold seeker of truth you….So again why do you NOT want global warming to be true or at least knowable? Really Dave why don’t you?

  15. muirgeo
    Posted Jan 10, 2006 at 1:01 AM | Permalink | Reply

    Re #13

    John S,

    Oops I think you miss posted. Silly…the Lemony Snicket board is just a little further down on your favorites drop down list.
    Here we were trying to find out how to best get an accurate representation or the best representation of the recent holocene climate trends. Something you’re probably not too interested in.

  16. IL
    Posted Jan 10, 2006 at 1:39 AM | Permalink | Reply

    #14,15 Muirgeo, insteead of making ad hominem attacks on people who do not agree with you, why not try arguing scientifically and from evidence. There has been lots of discussion and evidence in this site from proper journal papers showing that the reconstructions in multi-proxy studies are flawed both mathematically and from scientific procedural issues (tree rings respond not only to temperature but to CO2, fertilization, rainfall, etc etc, nor are any of these relationships linear as assumed).

    Surface temperature measurements are contaminated by UHI and we can argue about exactly how much – the satellite temperature measurements do show a very small increase but nothing like as much as the surface temperatures – that’s the real question, why is there that big difference?

    And so even if we accept that the global temperature is increasing how much is AGW and how much of it is due to the Earth emerging out of the Little Ice Age over the last 150 years?

    So for goodness sake, if you want to be taken seriously, argue about evidence rather than argue from absurdity (#14). Start with Bristle Cone pines, these are central to almost all the multiproxy studies, if they are removed from MBH98 the whole story changes (if you don’t know why or how, do some reading on the very accessible posts on this site). Why in your view are these a good proxy? How do you counter the criticisms made of the methodology?

    Get a grip on the issues rather than extrapolating to absurdity and automatically dismissing everyone who is not comfortable with the evidence presented for AGW as the dominant forcing for global climate as fools or ‘deniers’.

  17. Anders
    Posted Jan 10, 2006 at 1:50 AM | Permalink | Reply


    who said paleoclimate data is useless? You will certainly find no such claim at this website (apart from the one you make yourself). Paleoclimate data are very useful, however, what is shown on this webiste is that they do really have issues when it comes to understanding their connection with specific attributes such as temperature. What this site shows is that we really need to do much more work on the proxies to understand better how well they represent the climate.

  18. stephan harrison
    Posted Jan 10, 2006 at 3:03 AM | Permalink | Reply

    Re number 16 and the contamination of the surface record by UHI. I think that the recession of mountain glaciers in remote regions (away from the influence of UHI) suggests strongly that warming is global in extent. I also beleive that the attribution of this warming appears to be reasonably settled, although I’m aware that many of the posters to this site would disagree with me. Happy New Year everyone.

  19. per
    Posted Jan 10, 2006 at 3:07 AM | Permalink | Reply

    re: #9
    Dear muirgeo, if you google trenberth, cohn and lins, von storch, burger and cubasch on this site, you can read about their peer-reviewed publications, all of which raise substantive issues about climate reconstructions. The idea that it is just M&M who raise questions is wrong.

    One substantive point about their arguments is that some of the proxies used are not reliable indicators of temperature. Again, google for graybill on this site. The bristlecone pines do not show a good relationship with temperature over the time when we have thermometer records. If they don’t show a good relationship over the last ~century, why should we trust them to determine the temperature a thousand years ago ?

    There are numerous problems with the reconstructions which can be shown here. The PC analysis mines for hockey sticks. The temperature record shows autocorrelation, a statistical phenomenon which must be taken account of.

    Quite simply, it is not a measure of science to make your own proxy reconstruction. There are other useful ways to contribute; one such way is demonstrating that the proxy reconstructions so far, are not adequate as measures of temperature.

  20. muirgeo
    Posted Jan 10, 2006 at 10:55 AM | Permalink | Reply

    Re #16
    Get a grip on the issues rather than extrapolating to absurdity and automatically dismissing everyone who is not comfortable with the evidence presented for AGW as the dominant forcing for global climate as fools or “deniers’.

    Comment by IL “¢’‚¬? 10 January 2006 @ 1:39 am


    Do you think the glaciers in Glacier National Park were ever completely melted in the last 1000 years? How about the Ice Cap of Mt. Kilimanjaro? Do you think it was ever completely melted in the last 1,000 years?

    There is good evidence that both ice features have consistently existed for well over 1,000 years and there is very good evidence they will be completely gone (actually most of Glaciers glaciers are gone) in our children’s lifetimes.

    Am I extrapolating to absurdity or am I an unreasonable person to look at all the peer reviewed paleoclimate studies that we see in the spaghetti graph and the trends we see at Mt K and Glacier NP and to assume that Mann et al are basically right in spite of the large error factors involved in using proxy data?

    I suggest what we see here from the supporters of M&M IS extrapolating to absurdity. The basic argument here is that so much of the climate data is imperfect ( well DUHH!) and thus it is useless. That my friend is extrapolating to absurdity.

  21. Dano
    Posted Jan 10, 2006 at 11:15 AM | Permalink | Reply

    One substantive point about their arguments is that some of the proxies used are not reliable indicators of temperature.

    I believe the issue is their starting point may be contaminated by noise, making working backwards problematic. But since you are so non-specific, it is hard to address your er, point.

    Just to clear up any misunderstanding, mind you per. I’m sure you compose your posts to ensure there are no misunderstandings, right? As in,

    Quite simply, it is not a measure of science to make your own proxy reconstruction.

    Sure it is, despite whatever your phrasie-phrase is supposed to mean. Not-science is not following the scientific method when making the reconstruction. Just to clear up any misunderstanding, mind you per. I’m sure you meant to say that, right?



  22. muirgeo
    Posted Jan 10, 2006 at 11:26 AM | Permalink | Reply

    re #17

    If you look at the Hockey Stick graph and assume that the widest error bars represent the true range of climate for the last 1,000 years I still see cause for concern. The net temperature change from the peak warmth of the MWP to the trough coldness of the LIA is at best 1.3 C occuring over 200 years. We know there were significant societal effects with these relative climate extremes. What will be the effect when the temperature rises another 2 C in just 100 years and is well beyond anything civilization has experienced. Look at that graph and extend the Y-axis to include +/- 2 C of temperature change. Then the effect is even more dramatic. So even in the widest error margins of the Mann study I’d say we have some climate issues to deal with. If the mean of Manns study is close to accurate then it’s all the more true.

  23. per
    Posted Jan 10, 2006 at 11:40 AM | Permalink | Reply

    Dear Dano

    I believe the issue is their starting point may be contaminated by noise,

    well, as I said to Muirgeo, google Graybill on this site. What I said was correct; I make no warranty as to whether there is a temperature signal “contaminated by noise”, or just no temperature signal.

    despite whatever your phrasie-phrase is supposed to mean

    well, I am amused, since muirgeo is rehashing your argument. Producing a reconstruction is not a measure of the quality of your science; you can do climate science without doing reconstructions; pointing out the problems with reconstructions is good science. Take your pick.

  24. Posted Jan 10, 2006 at 11:56 AM | Permalink | Reply

    RE: #17

    Both the Greenland ice cap and Antarctic ice cap are thickening (on average).

  25. Posted Jan 10, 2006 at 12:04 PM | Permalink | Reply

    Re #14,

    I am rather sceptic about the predictive skill of GCM’s and about the weight that is given to some types of proxies (like tree rings) over others (like coral and stalagmites), be it that each type of proxy has its own problems. Despite that, I am very interested to see a highly reliable temperature reconstruction of the past millenia. That is crucial if one wants to know the real impact of GHGs in the (near) future. If the MBH98 reconstruction was right, then the influence of natural causes (~0.1 K volcanic, ~0.1 K solar in the pre-industrial period) on climate is weak and thus the influence of GHGs high (if one want to fit the instrumental temperature record) and GCMs will make projections at the high end of the IPCC-range. If the reconstruction shows far more variation (like Esper, Moberg, bore holes – the latter ~0.1 K volcanic, ~0.9 K solar), then the influence of GHGs is much lower and the projections will end at the low side of the IPCC range. That makes the difference between a benign warming and a probable disaster.

    Thus we desparately need reliable reconstructions, but I fear that tree rings are not the best items to get that goal…

  26. Dano
    Posted Jan 10, 2006 at 3:59 PM | Permalink | Reply

    It’s great, per, that you want to rehash others’ arguments, but (huh) the way you rephrased it changed the meaning.



  27. Terry
    Posted Jan 10, 2006 at 7:55 PM | Permalink | Reply

    Why aren’t the proxies showing abnormal readings currently?

  28. Steve McIntyre
    Posted Jan 10, 2006 at 8:42 PM | Permalink | Reply

    #23: that’s an excellent choice as well.

  29. Paul
    Posted Jan 10, 2006 at 9:18 PM | Permalink | Reply

    Steve… you are quite the tease…

  30. Ed Snack
    Posted Jan 10, 2006 at 10:58 PM | Permalink | Reply

    Well, it’s Dan again. Care to make the claim that Mann published his R2 statistics (in that well known paper of course), in this thread ? Or are you prepared to admit that it appears that he only published those parts of the statistical test, the parts that supported the conclusion he apparently wanted to come to. Do you believe it is OK to publish just those parts of the statistical tests that support your desired outcome and suppress those unfavourable ?

  31. Paul Penrose
    Posted Jan 10, 2006 at 11:32 PM | Permalink | Reply

    I’m really getting tired of the people that blow in here and claim that it’s somehow insulting or unprofessional to point out errors in published works, like MBH98, especially when an alternative study is not proffered. What utter BS. There was a time when the consensus of the experts was that the earth was flat and the sun revolved around the earth. Even questioning this was heresy – how could you be such an idiot. Sounds all to familar. The search for the real truth only happens after people question the status quo and are brave enough to point it out when the emperor has no clothes.

    If M&M’s analysis of MBH98 is wrong or flawed, then lay out your case. Stick to the facts and leave the logical fallacies at the water cooler. If you can’t show that M&M is wrong, then maybe you should take a closer look at the entire issue and consider whether it’s wise to just trust the consensus. Study, understand, and make up your own mind.

  32. Steve McIntyre
    Posted Jan 10, 2006 at 11:37 PM | Permalink | Reply

    Can anyone locate any of the following supposed supplementary informations; I can’t locate them anywhere, but sometimes they block me:

    Rutherford et al. [J Clim 2005] article here refers to top url. Others are from old notes.

    Mann et al [J Clim 2005] article here refers to:

  33. Steve McIntyre
    Posted Jan 10, 2006 at 11:41 PM | Permalink | Reply

    #31. Part of the difficulty that people have with not offering an alternative is that they don’t understand the idea of an audit. A comparison that I used to try, but it didn’t seem to get through was this: supppose that you’d given a sell recommendation on Enron with reasons; should you mix up your sell recommendation with a buy on some other stock, when you were certain of the one, but not the other. The MBH issue has been difficult enough by itself without introducing a whole other set of new variables and issues.

  34. muirgeo
    Posted Jan 11, 2006 at 12:37 AM | Permalink | Reply

    RE #31

    If M&M’s analysis of MBH98 is wrong or flawed, then lay out your case.

    Comment by Paul Penrose “¢’‚¬? 10 January 2006 @ 11:32 pm

    My case is simply this. First I admit I am in no way qualified to claim I understand the statistics well enough to make a decision about M&M’s case based on the statistics alone. Likewise I have to think that many here who have decided to side with M&M over Mann are like me unable to claim they understand the statistics well enough to make a decision based on them alone.

    My point is this. It’s great for people to question the methods used by Mann but what would really impress me is for M&M to point to one valid multi-proxy study that does exist or to do one of their own AND publish it in a peer reviewed journal. Until I see that happen I’m on the side of the spaghetti graphs.. since none other exist. The multiplicity of supporting peer reviewed paleostudies that complement Mann, the lack of absolutely NO contrary peer reviewed multi-proxy compilation and the factual evidence seen from Mt K and Glacier N P are the logistical pinnings which formulate my opinion on the matter.

  35. John S
    Posted Jan 11, 2006 at 1:38 AM | Permalink | Reply


    Your argument seems to boil down to bad data is better than no data. But that is a position that many, including myself, would argue against – there is a pithy aphorism “The only thing worse than no data is bad data.”

    One point that M&M are trying to make is that the existing studies are both methodologically and practically flawed. Wouldn’t it then be contradictory to endorse that flawed methodology by using it to create a marginally less bad reconstruction? It will still be a bad reconstruction.

    And, FYI, I understand the statistics well enough to make an independent decision that MBH is methodologically flawed.

  36. Armand MacMurray
    Posted Jan 11, 2006 at 3:48 AM | Permalink | Reply

    Re: #32
    Steve, all except the last ( show up for me. Perhaps you need to use some anonymous browsing software? I’ll email you the simple files, but some links are to non-trivial directory trees.

  37. James Lane
    Posted Jan 11, 2006 at 5:12 AM | Permalink | Reply

    muirgeo, I understand the statistics, and Steve’s case against MBH is a done deal.

    Your position is hard to understand. Are you saying “I’ll believe in crap, until someone produces some better crap”?

  38. Armand MacMurray
    Posted Jan 11, 2006 at 5:21 AM | Permalink | Reply

    Re: #34
    Muirgeo, you say:

    Likewise I have to think that many here who have decided to side with M&M over Mann are like me unable to claim they understand the statistics well enough to make a decision based on them alone.

    What’s the evidence behind your assertion? Like other recent posters, I don’t fit your statement.

  39. Steve McIntyre
    Posted Jan 11, 2006 at 7:21 AM | Permalink | Reply

    A couple of you have emailed me to say that you can access the Rutherford website. It looks like Rutherford has blackballed me from the site, just as Mann prevented me from accessing his FTP site at the University of Virginia after I started examining it. It is difficult to conceive of a pettier bunch of rascals.

    Last year I corresponded with Andrew Weaver, editor of Journal of Climate, about the then unavailability of this SI. I think that I’ll file a complaint about this. If authors are going to use grey archives as repositories for public access, then they should not be able to able to blackball people.

  40. Spence_UK
    Posted Jan 11, 2006 at 7:28 AM | Permalink | Reply


    I have sufficient grounding in statistics to follow the details of Steve’s claims and can vouch for the fact his arguments are well reasoned and quite valid.

    Although I wasn’t particularly familiar with PCA as a technique prior to looking into this, I didn’t simply take Steve’s word for it, I went out, read up on the technique, coded a segment of the MBH technique in MATLAB (my preferred stats tool, similar to R in many ways), and confirmed some of Steve’s assertions independently. (I suppose I kind of “audited the auditor” in some ways)

    Of course, Steve’s work has also passed peer review by (presumably) people competent to review the work.

    The spaghetti graphs show little beyond the fact that (1) it is warmer today than a couple of hundred years ago (hardly surprising as the instrumental record tells us this anyway) and (2) much before this, the multi-proxy studies so far disagree by pretty much the entire proxy calibration range (e.g. compare Moberg and MBH). We also know from von Storch (see comment at prometheus and thread on this blog) that the high profile of MBH probably caused publication bias. I would be cautious as to how much weight you give the spaghetti graphs. They should not be viewed as independent samples for a number of reasons (also discussed elsewhere on this blog).

  41. Dave Dardinger
    Posted Jan 11, 2006 at 7:43 AM | Permalink | Reply

    I think the thing to be considered when talking about statistical ability is whether a person can follow a statistical argument. If that hurdle can be met, the next one is whether or not people from an opposing position are willing to present the opposing view in an understandable way. In the particular case of M&M vs Mann et al. the problem is that while Steve is very willing to make his statistical case clearly, the M&M side won’t engage at all. AFAIK not one warmer / hockeyteam member has argued against Steve on the merits. This doesn’t prove him right, but it sure is a strong indication.

  42. per
    Posted Jan 11, 2006 at 8:11 AM | Permalink | Reply

    re: #31
    dear muirgeo
    the original mbh98 paper is basically a statistical paper, providing a method of using multiple proxies to reconstruct temperature. If you refuse to look at statistics, it seems that you can’t accept MBH as either true or false; but that you do not understand the basis for it. Nonetheless, there are some very funny bits and pieces about MBH98 which should be accessible to you. If you remove a very small number of records (some pines, cedars), which were known to be bad temperature indicators, from the MBH reconstruction, the entire shape of the reconstruction changes. MBH also apparently did statistical tests on their data, and some of them turned out to show that they had a problem, the R2 tests. They didn’t publish this data; and this is an ethics issue for scientists.

    Anyway, the MBH reconstruction is essentially a thermometer. But we know that thermometers are only good under certain circumstances; a mercury or alcohol thermometer will not work at -100 C, or at 500C. One of the really important questions that is posed, is whether the thermometer is working. If the thermometer is not working, it doesn’t matter how many reconstructions you do, they are all rubbish.

    And this brings me to one of the things that non-scientists find difficult. It doesn’t matter how good your intentions are, or indeed, how evil. You simply have to provide data that answers the questions, to do good science. Having a reconstruction might enable you to champion a very worthy cause; but the more tedious question is still appropriate; is the reconstruction meaningful ?

  43. jae
    Posted Jan 11, 2006 at 10:31 AM | Permalink | Reply

    Muirgeo: If you are in over your head, best not open your mouth.

  44. Jean S
    Posted Jan 11, 2006 at 10:56 AM | Permalink | Reply


    Mt. Kilimanjaro
    Glacier National Park

  45. Paul
    Posted Jan 11, 2006 at 11:37 AM | Permalink | Reply


    Unfortunately, it seems that World Climate Report doesn’t qualify as a “valid” source for many warmers, no matter if what it reports is true.

  46. Steve McIntyre
    Posted Jan 11, 2006 at 12:11 PM | Permalink | Reply

    Re Kilimanjaro: if glaciation recurred in the White Mountains CA and engulfed some of the very high subfossil bristlecones (from 7000 BP – treelines were then higher than at present) and then later receded disgorging the 7000 BP radiocarbon-dated bristlecones, would then mean that the glacier had originated before 7000 BP? Of course not. The presence of some old organics in the glacier only means that the glacier is not older than those organics rather than Thompson’s crazy opposite conclusion. Thompson completely ignores some rather young organics very deep in the glacier, which seem to me to require an explanation, which he does not provide.

    The Kilimanjaro glacier is only 50 m thick. The Quelccaya glacier to which an age of only 1500 years is attributed is nearly 3 times as thick. I haven’t seen any Kilimanjaro evidence that shows conclusively to me that it is older than Quelccaya. It might even be younger.

  47. ET SidViscous
    Posted Jan 11, 2006 at 12:21 PM | Permalink | Reply

    On the point of Ice, and Steve’s post just reminded me of it. I apologize in advance if I’m repeating myself here.

    Many of you will recall a certain doomsday scenario from a couple of months back where Russian permafrost was melting. The claim was that this melting permafrost would allow the frozen peat to decompose, releasing more CO2, runaway global warming and all (insert sarcastic arm waving here).

    Not a few people made the point to me that this was PERMAfrost. As in permanently frozen, since it was melting this was evidence of GW and AGW as it had never melted before. I would then make the point that since this PERMAfrost was peat, and peat is dense plant matter, and since plants don’t grow very well in frozen soil, like permafrost, the PERMA of permafrost was not to be taken too literally for timescales beyond a hundred years or so. Obviously it had been warmer in the distant past as here was actual evidence of plant matter growing in what is now a frozen wasteland.

    I’ve not seen any carbon dating of the peat to determine exactly when this plant matter grew, because obviously this would be interesting information.

  48. John G. Bell
    Posted Jan 11, 2006 at 1:53 PM | Permalink | Reply

    That is a great idea. If someone wanted to make a mark, checking the age of peat in “permafrost” around the world would be a great way to do it. Think how much that could tell you. It would be a fine use of grant money. You’d have something of real value in the end.

  49. Armand MacMurray
    Posted Jan 11, 2006 at 2:00 PM | Permalink | Reply

    Re: #39
    Steve, while I can certainly believe that Rutherford has blocked you from his site, I would suggest that this is one of those accusations that requires solid proof that the problem is intentional, rather than a technical issue. Perhaps you already have such proof, or perhaps John A can get some; I’m just concerned that filing a complaint without it might allow Rutherford to claim a PR victory without settling the matter.

  50. Paul Penrose
    Posted Jan 11, 2006 at 7:23 PM | Permalink | Reply

    While it is true that a number of papers have been published that basically agree with MBH98 (and subsequent MBH papers), they are all from a small group of people that are co-authors and/or friends of Mann. They are also mostly peer reviewed by the same small group. This kind of situation will always produce unintended, if not intended, bias every time. I find it very interesting that most of the criticism of MBH98 originates from well outside this circle of friendly researchers.

    I myself have struggled to understand all the statistical issues raised by M&M, and while I can’t claim to have complete mastery of them, I can say that I have a pretty good idea. This has raised a lot of questions in my mind about the validity of some of Mann’s data and techniques, and perhaps even the useful signal-to-noise ratio of any temperature signal in these proxies. Mann’s repsonses to these questions is even more troubling and makes me wonder if the situation is even worse than it appears. Whenever anybody avoids direct questions and resorts to Ad Hom attacks you have to wonder what they are hiding. Maybe they are not hiding anything, maybe they just like being contentious, but it’s generally not a good sign.

    Maybe I’m just silly, but I just can’t see spending billions of dollars and maybe even changing the course of civilization as we know it based on science that has so many questions. In this case “trust the experts unquestionably” just don’t cut it for me. Sorry if that sounds harsh, but anything less sounds pretty irresponsible to me.

  51. muirgeo
    Posted Jan 11, 2006 at 10:46 PM | Permalink | Reply

    RE # 46

    Re Kilimanjaro: if glaciation recurred in the White Mountains CA and engulfed some of the very high subfossil bristlecones (from 7000 BP – treelines were then higher than at present) and then later receded disgorging the 7000 BP radiocarbon-dated bristlecones, would then mean that the glacier had originated before 7000 BP? Of course not. The presence of some old organics in the glacier only means that the glacier is not older than those organics rather than Thompson’s crazy opposite conclusion. Thompson completely ignores some rather young organics very deep in the glacier, which seem to me to require an explanation, which he does not provide.

    Comment by Steve McIntyre “¢’‚¬? 11 January 2006 @ 12:11 pm


    If a 7,000 year old tree were engulfed by a glacier the inner most core of the tree would carbon date to 7,000 years plus the age of engulfment. The outer recently living tissue of the tree as with any other surrounding carboniferous recently living tissue would date to about the age of the engulfment. In other words when you date a glaciers advancement date you look for the youngest carbon dates to estimate the dates.

    Your calling Lonnie Thompson crazy are you? He is an incredible man and a great scientist. He’s lived a life most of us could just fantasize about. And I’m quite certain his ideas about dating glacier advancements the “crazy” ones.

  52. muirgeo
    Posted Jan 11, 2006 at 11:00 PM | Permalink | Reply

    Re #47

    Wow! Sid I’m lovin this. You guys are apparently great at statistics but some basic flub ups like Steves above and this one of yours Sid make me wonder if after I took a short course in statistics I would be finding similar glaring errors in your use of statistics to “debunk” Mann et al.

    Do you really believe that NO vegetation grows on the permafrost with the annual thaw? Here….. maybe a picture will help.

  53. ET SidViscous
    Posted Jan 11, 2006 at 11:04 PM | Permalink | Reply

    Then it wouldn’t exactly be permenantly frozen. It would be thawed (your word), now wouldn’t it.

  54. muirgeo
    Posted Jan 11, 2006 at 11:10 PM | Permalink | Reply

    Re # 35

    Your argument seems to boil down to bad data is better than no data.

    Comment by John S “¢’‚¬? 11 January 2006 @ 1:38 am


    There is a big difference between bad data and imprecise data. In paleoclimate studies we have imprecise data like listening to a radio station when the signal is week. You can here enough through the static to tell what they are talking about. Bad data is like being able to only get static or so few words as to not be able to comprehend anything they are talking about.

    If you want to claim the data is “bad” you’ll need to put it into writing, submit it and get it accepted to a respectable peer reviewed journal before I’m convinced you might have a point….same for M&M.

  55. Armand MacMurray
    Posted Jan 11, 2006 at 11:23 PM | Permalink | Reply

    Re: #52
    Muirgeo – it seems that you are confusing “permafrost” with “tundra.” The photo in your link shows lots of tundra and a small amount of permafrost underneath the seated gentleman’s shoes, where some tundra has been excavated down to beneath the permafrost. As ET points out, the permafrost is the subsoil that never thaws, underneath the top layer of the tundra. The top layer thaws seasonally and thus can support plant growth.

  56. Armand MacMurray
    Posted Jan 11, 2006 at 11:31 PM | Permalink | Reply

    Re: #51
    Steve said:

    Thompson completely ignores some rather young organics very deep in the glacier, which seem to me to require an explanation…

    Muirgeo said:

    …when you date a glaciers advancement date you look for the youngest carbon dates to estimate the dates.

    which agrees with what Steve said. How does Muirgeo turn that into

    basic flub ups like Steves above


  57. muirgeo
    Posted Jan 11, 2006 at 11:52 PM | Permalink | Reply

    Re # 50

    Maybe I’m just silly, but I just can’t see spending billions of dollars and maybe even changing the course of civilization as we know it based on science that has so many questions. In this case “trust the experts unquestionably” just don’t cut it for me. Sorry if that sounds harsh, but anything less sounds pretty irresponsible to me.

    Comment by Paul Penrose “¢’‚¬? 11 January 2006 @ 7:23 pm

    Absolutely Paul……I don’t trust those “experts”. Those “experts” who say it will cost billions and billions of dollars and ruin our economy to reduce our emissions. In fact, at some point we will need to switch over to other fuels. I live in America. We used to have a can do attitude. Need an A-bomb? No problem let’s do a Manhattan project. Need to land on the moon? No problem!!! Let’s do the Apollo project. Need to end are dependency on foreign oil? Need to end the fossil fuel industries grip on our democracy? Need to cut down on air pollution and kids with asthma? Need to avert an impending energy crisis? Need to show world leadership meant for the only existing superpower? Need to improve our national identity? Need to create vast new technologies we can sell the world over? Need to supercharge are economy with investments in our newest high tech endeavors? Need to change the course of civilization…in a good way? Tired of Bill Gates being the richest man in the world? Oh yeah and….need to respond to what a consensus of scientist call the worlds most urgent environmental problem even if some miners and economist say it isn’t? NO PROBLEM let’s do a ……humm what shall we call it…maybe…… the Edison Project.

  58. muirgeo
    Posted Jan 12, 2006 at 12:02 AM | Permalink | Reply

    re # 56


    Do you think Lonnie Thompson doesn’t understand this concept….as Steve is implying.

  59. muirgeo
    Posted Jan 12, 2006 at 12:13 AM | Permalink | Reply

    Re # 55


    I believe the tundra lies over the permafrost and the peat in the permafrost is likely a decomposition of the overlying tundra. Not a relics of a time when the surrounding environs were necessarily warmer.

    But maybe Sid is right and there might be a way to show definitively that the tundra has not thawed so in say60 or 500 or 6,000 or 50,000 years. That would help settle the debate about protocols and proxies and 2r’s. Armand, what would be your guess as to the last time the tundra thawed so? The 1930′s? The MWP? The middle holocene? The last interglacial?

  60. Armand MacMurray
    Posted Jan 12, 2006 at 12:47 AM | Permalink | Reply

    Re: #58/59
    I didn’t take any inference about Thompson other than that his data didn’t fully support his conclusion; there are many possible explanations for this(which don’t really interest me), but as I don’t see that any involve a “flub up” by Steve, I remain puzzled.

    The tundra is the whole shebang — the biome. The fact remains that organic material does not migrate into frozen soil, and certainly does not grow there. Thus, any organic material in the permafrost must have been there before the last time the permafrost froze. If you have a theory as to how subsoil that is currently permafrost could thaw without the surrounding environs being warmer, I’d like to hear it, but that’s the only explanation I can think of. As for timing, I don’t have any evidence, so there’s not much point in guessing.

  61. Ray Soper
    Posted Jan 12, 2006 at 2:26 AM | Permalink | Reply

    Sorry if this sounds disparaging George. I don’t doubt your sincerity or conviction, but surely you can’t be the best representative that the Hockey Team can put forward to argue their points for them? Can you?

  62. John S
    Posted Jan 12, 2006 at 3:04 AM | Permalink | Reply

    “If you want to claim the data is “bad” you’ll need to put it into writing, submit it and get it accepted to a respectable peer reviewed journal before I’m convinced you might have a point….same for M&M.”

    No need. It’s already been done. Graybill and Idso (1993), from their abstract “The growth-promoting effects of the historical increase in the air’s CO2 content are not yet evident in tree-ring records where yearly biomass additions are apportioned among all plant parts. When almost all new biomass goes into cambial enlargement, however, a growth increase of 60% or more is observed over the past two centuries. As a result, calibration of tree-ring records of this nature with instrumental climate records may not be feasible because of such growth changes.”

    You should read the paper to be absolutely clear that “may not be feasible” is a typically mild academic understatement.

    There’s more. Are you prepared to listen?

  63. Hans Erren
    Posted Jan 12, 2006 at 3:34 AM | Permalink | Reply

    re 61

    Armand, George isn’t sent, he is here on his own initiative.
    And he isn’t a sock puppet either.

  64. Armand MacMurray
    Posted Jan 12, 2006 at 4:00 AM | Permalink | Reply

    Hans, that was Ray Soper, not me. For now, I’m just waiting for the exciting conclusion of Steve’s story in Part 3!

  65. stephan harrison
    Posted Jan 12, 2006 at 5:01 AM | Permalink | Reply

    Re the postings about permafrost. The upper layer (a metre or so) always thaws in the summer and refreezes in the autumn and is called the active layer. It lies above the uppermost part of the permafrost (called the permafrost table). The permafrost itself never melts and can be 1km deep or so. The permafrost is deepest in Siberia which wasn’t covered by continental ice sheest during the LGM and therefore is probably a relic from those times. North American permafrost shows a distinct correlation with latitude and therefore may be younger than LGM.

  66. Steve McIntyre
    Posted Jan 12, 2006 at 5:59 AM | Permalink | Reply

    #51: George, you aid:

    If a 7,000 year old tree were engulfed by a glacier the inner most core of the tree would carbon date to 7,000 years plus the age of engulfment. The outer recently living tissue of the tree as with any other surrounding carboniferous recently living tissue would date to about the age of the engulfment. In other words when you date a glaciers advancement date you look for the youngest carbon dates to estimate the dates.

    First, while bristlecones are long-lived, I’m not talking here about living bristlecones, I’m talking about subfossil bristlecones i.e. ones that lived and died thousands of years ago. For example, a stump that lived from 7000 BP to 6000 BP. The bristlecones from this period are higher than modern bristlecones so it is possible that a glacier could engulf older bristlecones without engulfing modern bristlecones.

    Thompson has had a remarkable career, but that does not mean that he can’t oversell his points or jump to crazy conclusions. I have a particular bone to pick with Thompson because of his refusal to archive data for his widely cited Himalayan ice cores, but that’s a different story. I didn’t say that he was crazy, but that his argument for dating Kilimanjaro was crazy. There’s a huge difference. At the Chicago economics workshops that have been praised here or other such vigorous exchanges, I’m sure that people say that ideas are crazy without in any way demeaning or deprecating the author.

    This type of dating argument is very familiar in archaeology, in which I’ve done a lot of reading. If you have a young object in a stratum which is not an intrusion, then the stratum can be no older than the young object. A Coke bottle in a destroyed house would imply that it was modern rather than Middle Bronze Age. If you found a coin from the period of Alexander the Great (which are fairly common) in a destroyed house, all you could say without further evidence is that it’s more recent than Alexander the Great – you can’t conclude that it’s from the period of Alexander the Great, since it could be an heirloom (and archaeologists spend a lot of time disentangling this.)

    If you examine Thompson’s argument from this approach, his reasoning is extraordinarily weak (and, in fairness, it would probably have been preferable if I’d expressed my point in more measured terms like this.) But it’s really frustrating to see supposedly eminent people make arguments that wouldn’t pass muster from an undergraduate archaeologist (or even common sense).

    Your own counter-example completely fails so don’t accuse me of a “flub” here. You also failed to name any “blatant mess-ups” in my “books” or “papers”.

  67. Posted Jan 12, 2006 at 7:21 AM | Permalink | Reply

    Re #59
    Muirgeo, permafrost was more thawned anyway than today in the preceding interglacial (the Eemian), with forests (some 600 km) more north, where now tundra is in Alaska. See: (and look for Eemian). Arctic ice may have been melted completely in summer and winter ice in the Bering Street was some 800 km more north… Al without the help of humans…

  68. Dave Dardinger
    Posted Jan 12, 2006 at 8:20 AM | Permalink | Reply


    I’m glad Steve was able to set you straight, so I don’t have to. But one technical thing. You really need to learn to use the block-quote. It’s on the line about the message box in which you type replies. You can either insert ‘b-quote’ at some point in you pre-existing message by pressing the button, in which case the button turns to a ‘/b-quote’ button which you can insert whereever you want to end the quote, or you can just highlight a section of text you want to have block-quoted and press the button and both the ‘start b-quote’ and ‘end b-quote’ tags will be inserted.

    This is an example of a b-quote

    You’ll note it lets you tab and ‘highlight’ at the same time.

    Generally here, all quotes which are more than a few words should be block-quoted.

  69. Michael Jankowski
    Posted Jan 12, 2006 at 9:34 AM | Permalink | Reply

    What a shame that South Korean researcher took such a hit for his fraudulent stem cell work. To think that NONE of his critics and skeptics submitted new stem cell lines to replace his fraudulent ones. Isn’t that how it should have gone, George? Especially after his work made it through peer-review and was so widely accepted…

  70. per
    Posted Jan 12, 2006 at 9:35 AM | Permalink | Reply

    re: #54

    If you want to claim the data is “bad” you’ll need to put it into writing, submit it and get it accepted to a respectable peer reviewed journal before I’m convinced you might have a point….same for M&M.

    that would be like cohn and lins showing that much paleoclimate data is autocorrelated ? That would be like Graybill’s paper showing that the tree-ring width data doesn’t correlate well with temperature ? Von Storch’s paper showing that MBH’s method does not detect variability ? The Cubasch paper showing problems with the MBH reconstruction ? M&M’s papers showing further defects in MBH98 ?

    This seems to be a one-sided conversation where you are not paying attention to any information you get. And here is me thinking you are an open-minded scientific sort :)

  71. jae
    Posted Jan 12, 2006 at 10:48 AM | Permalink | Reply

    George: MBH’s reconstructions don’t even show the LIA or MWP. Considering this and all the other literature, and the fact that Mann won’t even release all his information, how can you possibly continue to defend all this tree ring proxy nonsense? You must have some type of religious belief in global warming. It simply does not make sense to spend trillions of dollars to try to “fix” a problem, when it is so uncertain that there is even a problem.

    Indeed, I am amazed that so many scientists put so much stock in tree ring data. Tree growth is affected by so many things (rainfall timing and amount, solar intensity, competition from neighboring vegetation, nutrient avaliability, fires, etc.) that any temperature effects would almost certainly be lost in the “noise.” Even a simple thunderstorm during the growing season can greatly affect growth by adding some nitrogen.

  72. Terry
    Posted Jan 12, 2006 at 8:08 PM | Permalink | Reply


    Your posts are excellent … by far the best of the pro-AGW folks who post here.

    Your point about there being so much evidence in favor of AGW is quite good. This basically is the main pro-AGW point for non-scientists and is the main perception that RealClimate seeks to prove or create. To seriously doubt the purported consensus, therefore, requires a theory of how so many people and journals could believe as they do. You need some sort of publication-bias theory coupled with some sort of theory about how academics tend to herd along party lines because it is advantageous to do so. Personally, I think this is possible, because there have been many cases of scientific fields and professions that have maintained consensus positions that were wrong well after there was good evidence it was wrong. (Freudian psychology comes to mind.) On the other hand, there are many scientific fields where certain things are well established despite there being a few cranky contrarians. (Intelligent design comes to mind.)

    My personal take is that there is enough science behind AGW to believe that it might be true, and that the odds of AGW are likely greater than 50-50. However, a lot of very unconvincing junk is getting a free pass as long as it is pro-AGW, so I think it is likely that the “concensus” exaggerates both the certainty and the severity of
    AGW. While I wouldn’t be surprised if AGW leads to a 1.5 degree warming this century, I also wouldn’t be surprised if it turns out to be essentially irrelevant and overwhelmed by other heretofore-unknown factors that drive climate. I also wouldn’t be surprised if it is actually beneficial.

    A suggestion. If you can’t understand the statistics of MBH, try carefully investigating one thing you can. Then use what you learn to judge the evidence as a whole.

    Perhaps hurricane severity, or the disappearing frogs is a good place to start. Start with one of Patrick Michaels rebuttals, say for the frogs, or for hurricanes (see also

    Then read RealClimate’s take. For hurricanes, see (pay special attention to Stickerey’s comments #16 and #20 which I thought were quite trenchant), and (I haven’t waded through all the comments); see also Landsea’s (one of the most respected hurricane researchers) comment on Emanuel at … note especially Figure 2 and the related discussion.

    Decide for yourself if the AGW folks are accurately representing the strength of the evidence or if they are overstating the case for AGW and understating the uncertainties and counter evidence. Then, assume that the rest of the evidence is equally correct or overstated.

    Hope this helps.

  73. Steve Bloom
    Posted Jan 13, 2006 at 1:44 PM | Permalink | Reply

    Let’s see, Terry, first you cherrypick a couple of narrow examples that you obviously think have particular problems, then you say “assume that the rest of the evidence is equally correct or overstated.” Now there’s your scientific method in action. You should recommend the same approach to all the solar-philes who frequent this site.

    BTW, Emanuel is a more respected hurricane researcher than Landsea.

  74. John A
    Posted Jan 13, 2006 at 1:58 PM | Permalink | Reply

    Re #73

    Ah yes, when you can’t rebut the citations, accuse them of cherrypicking them.

  75. muirgeo
    Posted Jan 13, 2006 at 9:09 PM | Permalink | Reply

    Re #72


    Thanks for the compliment. I don’t get too many of those here.

    Anyway I do read both sides of the debate. I probably spend more time on boards and with literature that might counter my views versus that which supports my views. My assessment is that the overwhelming majority of the evidence supports the general consensus found in the IPCC. I suspect they are pretty much spot on. No they are not 100% accurate. To the contrary they admit too much uncertainty but I believe the answers are found with in their “error bars”. With each year that passes the accumulation of new data and trends seems to consistently add to the case made by the IPCC. Look at the satellite data. Also it’s interesting that the hurricane discussions you linked to were mostly in the spring and early summer. Much new data has blown in just since then.

    Looking at the CRU graph on global temperature trends I find the consistent march of the trend very convincing. I just wonder how many more up ticks on the y-axis it will take before some skeptics also become believers. If I couldn’t real off 30 some odd climate trends that confirm/ support the surface data I too might be a skeptic.

  76. per
    Posted Jan 13, 2006 at 10:13 PM | Permalink | Reply

    Anyway I do read both sides of the debate. I probably spend more time on boards and with literature that might counter my views versus that which supports my views…

    How delightful. I am glad you have looked at all the evidence.

    Are you going to be able to tell us about any specific item of this evidence ? After all, you have made some pretty specific claims about “blatant errors“, and it would be nice for us to learn from you :)

  77. Willis Eschenbach
    Posted Jan 13, 2006 at 10:23 PM | Permalink | Reply

    Muirgeo, either answer the questions or go home. I have no use for your drive-by shooting style, you come in, you p*ss on the roses, and then you talk about anything but backing up your scurrilous claims.

    Turns my stomach,


  78. muirgeo
    Posted Jan 13, 2006 at 11:04 PM | Permalink | Reply

    Re # 77


    I already did answer this and I am already at home.
    Sorry about your stomach…really I am. However, you might want a little Pepto Bismol before reading this;

    Those were roses I watered…looked like nettles to me. Maybe it has to do with the tint of your glasses.

  79. Steve McIntyre
    Posted Jan 14, 2006 at 12:01 AM | Permalink | Reply

    George, you have still not identified any "blatant errors" or even any errors in McIntyre and McKitrick.

    Ross made a programming error in a paper that I had nothing to do with, concerning the format for cosine latitude calculations. It was identified promptly because Ross made code available; Ross promptly acknowledged and corrected. What light does this shed on whether Mann might also have made computer programming errors? I would submit that, far from this being evidence that Mann didn’t make errors, it shows the opposite – that people make errors and that it’s a good idea to make code available for scrutiny.

    All of us make errors. There’s a saying that I like: "Good judgment is the product of experience, which is the product of bad judgment". I’ve made lots of errors in my life. However, so far, touch wood, I’ve been pretty lucky in avoiding clangers in our climate papers (notwithstanding what you may think). There’s been far more time and effort spent trying to find fault with my work than ever went into testing MBH98 in the first place. The fact that I’m still standing should tell you something.

    Bcause we’re all human and everyone can make errors is sufficient to show the importance of "full, true and plain" disclosure, proper archiving of data and methods and adequate due diligence.

    Ironically, in addition to the many problems that we identified, Mann also made an error in respect to cos latitude (identified by von Storch). There is an amusing debate at Wikipedia (Connolley’s involved naturally) in which Connolley tries to justify why Ross’ cos latitude error should appear in Wikipedia, but Mann’s should not. Connolley has distrubingly tried to make it appear as though I was involved in the cos latitude.

    I also completely deny a "flub up" our 2003 E&E paper as you allege. The actual claims made in the paper have stood up very well, despite the restrictions on the material that we had access to. (see the Scorecard that I wrote earlier this year).

    Let me make it perfectly clear that all the original data was included in our E&E paper. We carried out a huge recollation of hundreds of tree ring series to ensure a clean data set, unlike the data archived at Mann’s FTP site. What remains uncertain is why the flawed data set at Mann’s FTP site was developed and how it was used (Mann’s assertion that it was prepared for us is simply false as could be determined by the date long prior to our request.)

    There has been an evolution in our views as more information has become available, but I would deny that the "goal posts are being moved". It’s rather that Mann keeps trying out different ways of wiggling out of the situation, so that you have to respond in different ways.

    In the 2003 paper, we pointed out problems with the principal components calculations. At the time, we could not explain what was wrong with his PC series, but we were able to fully explain it in the 2005 papers. In our 2003 paper, we pointed out the impact of using updated series versions. By using archived data, we inadvertently discovered the impact of Mann’s "editing" of the Gaspe data, but the quantification of this effect only came later.

    The identification of the bristlecones came through following the impact of the flawed PC method. Their impact on the reconstruction was shown indirectly in the 2003 reconstruction; the identification of their role in the situation came through further analysis of the 2003 results, but in no way represents a resiling or moving the goal posts.

    In many forensic situations, it is surprising how often they start with fairly small quality control issues. Auditors are very sensitive to telltales, which often are symptoms of deeper problems. Even Hwang started with some small issues – which he, like Mann, attempted to explain as resulting from the supply of the "wrong" data. The response of stem cell researchers was that it was simply not possible for a researcher to supply "wrong data" for such an important study and that this meant that everything needed to be looked at, which the Korean bloggers started doing. This led to a full-scale university audit of Hwang. But prior to the full-scale university audit, I think that fewer and less serious problems had been raised with Hwang than we’ve raised with Mann.

    The issues of disclosure and due diligence are not a change of focus, but merely something that I coulc not avoid remarking on. The withholding of adverse information is a serious offence in a prospectus and I’m surprised that climate scientists don’t seem to be troubled by it.

  80. nanny_govt_sucks
    Posted Jan 14, 2006 at 12:04 AM | Permalink | Reply

    However, you might want a little Pepto Bismol before reading this;

    Are you accusing Steve of making an error in Ross’s paper? Perhaps you have Ross and Steve confused.

  81. Kenneth Blumenfeld
    Posted Jan 14, 2006 at 12:45 AM | Permalink | Reply


    I have noticed that all topics eventually converge to one or two common threads. For balance, it happens at realclimate and climatescience too. Just an “obs.”

  82. Terry
    Posted Jan 14, 2006 at 1:03 AM | Permalink | Reply


    Anyway I do read both sides of the debate. I probably spend more time on boards and with literature that might counter my views versus that which supports my views.

    It shows, that is why your posts are often good. It is very important to actually engage the other side of a debate.

    A tip. Try avoid responding too much to the more provocative posts. Threads tend to descend into name-calling when that happens. (The thread about browsing undergraduates has descended to near-kindergarten levels.) It is too easy to respond to the weakest and most outrageous comments. Engaging the best ones is the hard part.

  83. Terry
    Posted Jan 14, 2006 at 1:08 AM | Permalink | Reply


    Please continue to post … it raises the average level of discourse.

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