Quick Reaction to the NRC Hockey Stick Report

June 22nd, 2006

Posted by: Roger Pielke, Jr.

My reading of the summary of the report and parts of the text is that the NAS has rendered a near-complete vindication for the work of Mann et al. They report does acknowledge that there are perhaps greater uncertainties in temperature reconstructions, reducing Mann et al.’s claim of warmest decade/year in 1,000 years down to 400. Nonetheless, I see nothing in the report that suggests that Mann’s research is significantly flawed, nor any calls for release of his data or algorithms, though the report does say in very general terms that such release is a good idea. I am not a climate scientist, but my reading of the section that deals with criticisms of Mann et al.’s work (starting at p. 105) is that while these critiques raise some interesting points, they are minor issues, and the committee find’s Mann et al.’s original conclusion to be “plausible.” I’d bet that the word “plausible” will be oft invoked as one of the take home messages of the report.

So what to make of this? The NRC has come to the conclusion that the hockey stick debate is much ado about nothing, and make the further point that this particular area of science is not particularly relevant to detection and attribution of human caused climate change. I am certain that research on this subject will continue, but hopefully this NAS report will allow the rest of us to focus on the policy debate rather than this particular issue of science.

I would have liked to see the report get into far more detail on science policy questions, such as release of data, methods, code, etc. and mechanisms of peer review, and IPCC authors reviewing their own work. However, I recognize that these issues may have been interpreted as outside their charge and the committee was not empanelled for this purpose.

Is this the final word on the “hockey stick”? My guess is that for most people, yes, especially if Representative Boehlert, who requested the report, is satisfied with the answers to his questions.

45 Responses to “Quick Reaction to the NRC Hockey Stick Report”

  1. Roger Pielke, Jr. Says:

    The AP also shares my interpretations:

    “The National Academy scientists concluded that the Mann-Bradley-Hughes research from the late 1990s was “likely” to be true, said John “Mike” Wallace, an atmospheric sciences professor at the University of Washington and a panel member. The conclusions from the ’90s research “are very close to being right” and are supported by even more recent data, Wallace said.”


  2. 2
  3. jfleck Says:

    My take on the importance of the report is that, for folks like you and I – non-scientists who have need to understand and apply the science – the report is invaluable. It provides the sort of expert review that we’ve needed to ground our discussions of what we know and don’t know about the paleo record.

    I harbor no illusions, though, that this will settle the tribal climate wars tussle.

  4. 3
  5. Roger Pielke, Jr. Says:

    Rep. Boehlert speaks out on the NAS report:

    “June 22, 2006

    Statement by Science Committee Chairman Sherwood Boehlert (R-NY) regarding the National Academy of Sciences Report, Surface Temperature Reconstructions for the Last 2,000 Years:

    “I think this report shows the value of Congress handling scientific disputes by asking scientists to give us guidance. The report clearly lays out a scientific consensus position on the historic temperature record. One element of that consensus is that the past few decades have been the hottest in at least 400 years. There is nothing in this report that should raise any doubts about the broad scientific consensus on global climate change – which doesn’t rest primarily on these temperature issues, in any event – or any doubts about whether any paper on the temperature records was legitimate scientific work. The report does show, unsurprisingly, that scientists need to continue to work to develop a more precise sense of what global temperatures were between the beginning of the last millennium and about 1600. Congress ought to let them go about that work without political interference.”

  6. 4
  7. Roger Pielke, Jr. Says:

    Sorry, forgot link to Boehlert statement:


  8. 5
  9. Indur Goklany Says:

    Roger — I was unable to access the report itself. However, assuming that your precis is accurate.I must note that from the policy perspective, there is quite a difference between warmest-in-400 years and warmest-in-1,000 years, particularly when much of the first portion of the 400 yr period is approximately coincident with the Little Ice Age. I would not say, based on this that the hockey stick is, therefore, much ado about nothing. Clearly, many must have thought it a big deal for the 1,000 yr hockey stick diagram to be reprinted ad infinitum in debates dealing with CC. [It might be useful to go back and review the hype surrounding the 1,000-yr diagram at the time it was published.]

    Second, I must note that many things are scientifically plausible without necessarily being true. In fact, that’s one way I would define “plausible”. [BTW at what level of significance is something deemed "plausible"? I doubt that even the biggest skeptic of GHG-induced warming would say that it is not plausible.]

    I do believe that in order to be of use to policy analysts and policy makers, reports such as the IPCC’s or the NAS’, should go beyond telling us what is “plausible.” They need to say whether it is “probable,” and to objectively quantify that probability.

    Finally, the real issues are (among other things) the extent to which recent warming is due to GHG-induced warming (as opposed to anthropogenic warming from all causes), and the extent to which they are outside the bounds of natural variability. So from that point of view, one could always have held that the hockey stick — not to mention the debate about it — was much ado about the wrong thing.

  10. 6
  11. Roger Pielke, Jr. Says:

    Indur- Thanks.

    Your write: “one could always have held that the hockey stick — not to mention the debate about it — was much ado about the wrong thing.”


  12. 7
  13. James Bradbury Says:

    Hi Roger,

    Good post…. made complete by an appropriate response from Rep. Boehlert (too bad his time is up at the House Science Committee). Thanks for the link.

    As you said, “…hopefully this NAS report will allow the rest of us to focus on the policy debate rather than this particular issue of science.”

    Here, here!

  14. 8
  15. James Bradbury Says:


    I think your list of questions is apt, judging by the fact that the same basic issues were raised and addressed at the press briefing, following the release of the report. I recommend that you have a listen:


    (You’ll also find links to the report and other info at the same website)

    Best, James

  16. 9
  17. Roger Pielke, Jr. Says:

    Boston Globe:

    “A signature piece of evidence for global warming — a chart showing that a sharp rise in temperatures made the late 20th century the warmest period in at least 1,000 years — is most likely correct, a national panel of scientific experts concluded today.”


  18. 10
  19. Dario Says:

    I find it interesting that “plausable” has already morphed in to “likely”.

  20. 11
  21. Benny Peiser Says:


    You ponder whether the NRC report will be the final word on the “hockey stick.” Well, as far as Senator Inhofe is concerned, Mann’s hockey schtick is broken beyond repair. Inhofe clearly feels that his scepticism has been vindicated, as he makes clear in his press release below:


    Washington, D.C.-Sen. James Inhofe (R-Okla.), Chairman of the Committee on Environment and Public Works commented on today’s congressionally commissioned review by the National Academy of Sciences that shows that Dr. Michael Mann’s “hockey stick” study was flawed, specifically refuting some of its most often-cited conclusions.

    The National Academy of Sciences’ “Surface Temperature Reconstructions for the Last 2000 Years” noted in their summary that there were “relatively warm conditions centered around A.D. 1000 (identified by some as the ‘Medieval Warm Period’) and a relatively cold period (or ‘Little Ice Age’) centered around 1700.” The hockey stick constructed by Mann and his colleagues purported to show temperatures in the Northern Hemisphere remained relatively stable over 900 years, then spiked upward in the 20th century.

    “Today’s NAS report reaffirms what I have been saying all along, that Mann’s ‘hockey stick’ is broken,” Senator Inhofe said. “Today’s report refutes Mann’s prior assertions that there was no Medieval Warm Period or Little Ice Age.”

    The NAS report also stated that “substantial uncertainties” surround Mann’s claims that the last few decades of the 20th century were the warmest in last 1000 years. In fact, while the report conceded that temperature data uncertainties increase going backward in time, it acknowledged that “not all individual proxy records indicate that the recent warmth is unprecedented…’

    In addition, the NAS report further chastises Mann, declaring “Even less confidence can be placed in the original conclusions by Mann et al. (1999) that ‘the 1990’s are likely the warmest decade, and 1998 the warmest year, in at least a millennium …’”

    “This report shows that the planet warmed for about 200 years prior to the industrial age, when we were coming out of the depths of the Little Ice Age where harsh winters froze the Thames and caused untold deaths.

    “Trying to prove man-made global warming by comparing the well-known fact that today’s temperatures are warmer than during the Little Ice Age is akin to comparing summer to winter to show a catastrophic temperature trend.”

  22. 12
  23. Indur Goklany Says:

    If I were a headline editor, my headline would read: “hockey stick handle shortened 60 percent”. I dunno — is that broken?

  24. 13
  25. Benny Peiser Says:


    What do you get when you shorten a hockey stick by 60%? A boomerang …. :-)

  26. 14
  27. kevin v Says:

    isn’t it amazing that Sen. Inhofe’s staff of non-scientists can take a conclusion of technicians/scientists and completely turn around their original meaning? I love politics.

  28. 15
  29. Lubos Motl Says:

    We must have studied very different sources. The sources I studied, including the press conference, confirm every single criticism that was ever raised against works like Mann et al.

    Let me quote some points in the audio, as described at


    The confusion who is responsible for overselling MBH98 and MBH99 and creating a feeling of certainty where there is no certainty is discussed at 19:20 of this

    * real audio from the press conference.

    If you go to 25:30 of this audio, a distinguished NAS scientist explains that the belief that Mann’s results were definitive were not Mann’s fault but rather the community’s fault. I can’t believe he’s serious. Is he talking about the same Mann who established his own propagandistic blog to promote his weird speculations, deny all criticism, and describe the critics as corrupt people? Of course that it was also a fault of the climate community because it is mostly a lousy one, but indicating that Mann is innocent is just crazy.

    At 35:00 into the audio, they discuss Mann’s flawed usage of the principal component analysis. At 37:30, they discuss why the bristlecone pines are not good temperature proxies. At 50:00, a panel member answers “Yes” to the question whether he is saying that the odds than Mann is right are around 2:1 – which means “almost completely uncertain”.

    At 53:40, a desperate activist / journalist tries to criticize the NAS panel that they used the word “plausible”. How could this have happened? ;-) The same crazy journalist even says that there is no evidence for string theory but we can say it’s “plausible”. I assure this comrade that string theory is much more plausible than a catastrophic global warming. ;-) Around 54:30, they also agree with your humble correspondent that quantitative estimates of “Bayesian” confidence levels in this context (and similar contexts) are meaningless and the real uncertainty can’t be quantified. Around 1:03:00 into the audio, it is being discussed how much money is being wasted for climate research whose insights are ever more murky and questionable. At 1:06:30, they say that the variability – and thus also the uncertainty – is higher than thought previously.

  30. 16
  31. John Lish Says:

    I also love politics, especially when a report effectively substantiates all the criticisms about the lack of robustness of the MBH98 study yet covers these through the use of hand-waving. There is nothing more political than that.

    Roger, I suggest you take a closer look at the criticism in chapters 9 & 11 and then consider Hans Von Storch’s press release about the findings of the report where he states that the Mann et al study is statistically meaningless.

  32. 17
  33. per Says:

    there is a good deal of “spinning” going on, but you have to look at the science. MBH made the claim that, within defined 95% error bars, they could reconstruct temperatures back for a millenium. The NAS panel has concluded that you can only go back 400 years, and that beyond that, the nature of the unquantifiables is such that you cannot really assign rigorous probabilities to temperature reconstructions. That is a fairly stark difference.
    Just on the issue of “plausible”, I would recommend you use a dictionary, e.g. “apparently reasonable”. Since when did “plausibility” count as an endpoint of scientific proof ?
    The report also has some fairly severe analysis of some the issues raised by MBH, such as problems with the statistical analysis, and problems with reliance on bristlecone pines, which they conclude to be not reliable temperature indicators.
    I appreciate it is nice to be able to focus on policy, with the science being settled. However, it should be readily apparent that this report requires much retrenching of previously held beliefs, and may further undercut much of the temperature reconstructions. I do not see how you can see that this report settles the science.

  34. 18
  35. Roger Pielke, Jr. Says:

    Lubos, John, Per-

    Thanks much for your comments. But I don’t see where you disagree with my post chracterizing the report.

    But let’s cut to the chase — So what?


  36. 19
  37. Steve Hemphill Says:

    So, it’s now warmer than anytime since the Little Ice Age? Duh. Most of the warming is anthropogenic, but only some of that is GHG’s? Nothing new there to those not under the influence of the Church of IPCC.

    The big thing though, is that the National Academy of “Sciences” didn’t call for the release of the algorithms nor data – therefore condoning the dilution of science, since a major tenet of science is repeatability – isn’t it?

    It used to be…

  38. 20
  39. per Says:

    “I see nothing in the report that suggests that Mann’s research is significantly flawed,”
    they have chucked out his conclusions re: 1000-1600, and describe them as merely “plausible”, or apparently reasonable. That means they have accepted several of the methodological arguments about MBH, and that they are not “minor”, but substantively change the conclusions drawn from this work.
    “The NRC has come to the conclusion that the hockey stick debate is much ado about nothing,”
    yes; so why have a whole report on this ? I don’t think the report substantiates this comment.
    “this particular area of science is not particularly relevant to detection and attribution of human caused climate change.”
    It strikes me that you should evaluate the evidence, rather than simply accepting on faith. I can show that your statement is simplistic.

    Consider these two scenarios; that we have perfect knowledge of global temperature for the last five millenia. (1) temperature is essentially invariant, and starts to rise drastically only post-1850 (2) temperature jumps about all over the place, and temperatures warmer than today are common.
    Can you really consider that the information in these alternative scenarios would not impact on the confidence we give our (non-empirically tested) models ?

    “so what ?”- the science isn’t settled. Makes it difficult to derive policy based on a settled science.
    cheers :)

  40. 21
  41. Roger Pielke, Jr. Says:

    Per- Thanks. I did say that the research will continue, clearly the MBH studies weren’t the last word. However, we disagree when you write:

    “the science isn’t settled. Makes it difficult to derive policy based on a settled science.”

    We had a conversation here a while back with the various folks involved in this debate, and Steve Mc., Ross Mc., and a couple RC guys agreed that the HS debate wasn’t relevant to climate policy, but was relevant to some questions of research policy. The NRC seems to agree. So while you may think that the HS debate is climate policy relevant, I don’t see it.


  42. 22
  43. Richard Stewart Says:

    I agree with Benny that this report refutes Mann more than it supports him. It only agrees with him for the first 400 years back; almost everyone agrees with that anyway. To go back 1000 years, it is merely “plausible”. As someone pointed out in an earlier post, that only means it could be true, not that it is or even is “likely”. Once again, a panel has written a report and panel members have immediately been quoted in the paper stating a different conclusion than the report says. There is a huge difference between plausible and likely.

    Furthermore, the panel said that Mann’s claim that the 90’s was the warmest decade and 1998 the warmest year could not be supported by the data. I have also read in reference to “An Inconvenient Truth” that 2005 was the hottest year in the last 1000 years. No doubt this cannot be supported by the historical data either.

    The Hockey Stick itself may not be relevent, but many people are using it to deny MWP and LIA and this report supports the existence of both these.

  44. 23
  45. e. ou Says:


    In the interest of the public is it possible to have a parallel analysis of the NAS report from both sides of the debate. I went through the realclimate and the climateaudit website, with both sides quoting and claiming their positions were correct. I dont know who is “cherry picking” and up to what extent.

    Is there a site which is an “honest broker”?

  46. 24
  47. Jim Clarke Says:

    For years, those who have said the GCMs have no skill because we can not predict the future state of a coupled, complex, non-linear system with mathematical equations, have often recognized ‘pattern recognition’ as a legitimate way to predict such future states. Today, the NRC report seems to be saying that there is no way to know what those historical patterns are with any accuracy.

    If both statements are true, we are left with a profound ignorance of climate change, whether natural or man-made!

    That sounds just about right!

    All we have left are real-world observations, which according Roger Pielke Sr. and his references at Climate Science, indicate that about 1/4 of the warming over the last 150 years may be due to CO2 emissions.

  48. 25
  49. Jim Clarke Says:


    Since the late 1990’s, there have been only 2 main reasons to believe that CO2 is the primary driver of recent climate change, the GCMs (i.e. AGW theory) and the Hockey Stick. If you take away the Hockey Stick, you are left with a much weaker argument.

    I am not sure how you can claim that it is not relevant to the policy debate. It seemed to be very relevant 8 years ago!

  50. 26
  51. Andrew Dessler Says:


    I agree with your assessment of the report. However, expecting the hockey conspiracists to agree with your assessment is as likely as having your kid say after an argument, “you’re right, dad, I now see your point of view and it’s clearly more reasonable than mine.” Ain’t gonna happen. Ever. Much like dysfunctional families that require therapy, this argument is the glue that holds their community together. Without it, they’re lost.


  52. 27
  53. Roger Pielke, Jr. Says:

    White House Press release on the NRC report:

    Contact: Ben Fallon (202) 456-6098 bfallon@ostp.eop.gov

    Statement of Dr. John H. Marburger, III on the National Academies of Sciences Report “Surface Temperature Reconstructions for the Last 2,000 Years”

    WASHINGTON — Dr. John H. Marburger, III, Science Advisor to President George W. Bush and Director of the White House Office of Science and Technology Policy (OSTP), issued the following statement today regarding the release of a National Academies of Sciences report titled, “Surface Temperature Reconstructions for the Last 2,000 Years”.

    “The report released today by the National Academies is consistent with their 2001 report that was commissioned by the Administration, and with recent reports issued by the Administration’s Climate Change Science Program. The President has made clear his view that, while resolving scientific uncertainties is important, we need to concentrate on practical, technology-based actions at home and abroad that will cut greenhouse gas emissions — actions such as implementing the President’s Advanced Energy Initiative and full implementation of last year’s energy bill. That bill contains billions in research and development dollars and tax incentives, requirements for appliance efficiency, new fuel economy requirements and new processes to bring more zero- emission energy and renewable fuels on line. The U.S. is leading in greenhouse gas reduction technology investments for the long term.”

    President Bush is Addressing Climate Change

    Ambitious Goal: In February 2002, President Bush committed to cut U.S. greenhouse gas intensity — how much we emit per unit of economic activity –by 18% through 2012.

    Real Progress: U.S. greenhouse gas intensity declined by 2.0% in 2003 and by 2.5% in 2004, well ahead of the President’s goal. Demonstrated Action: Our energy policies foster investment in technologies that improve energy security and reduce pollution and greenhouse gases. 

    Energy Policy Act of 2005 and other law – $5B in tax incentives over five years for clean energy systems and highly efficient vehicles; mandatory renewable fuel and energy efficiency standards 

    Advanced Energy Initiative – 22% increase in DOE research funding to help make alternative energy technologies practical and affordable, including ethanol, wind, solar, geothermal, clean coal, nuclear energy, hydrogen, and fusion.

    Strong at Home: Between 2001-2006, $25 billion in spending on climate change programs, by far the most in the world.  Climate Science Program – nearly $2 billion/year  Climate Technology Program – nearly $3 billion/year Leading the World: The U.S. has partnerships with countries that represent over 70% of global greenhouse gas missions. 

    Asia-Pacific Partnership on Clean Development and Climate 

    Methane-to-Markets – 17 countries working to capture 50 million tons (MTCE) of methane emissions to provide clean, affordable energy 

    International Partnership for Hydrogen Economy, Carbon Sequestration Leadership Forum & Global Nuclear Energy Partnership.

  54. 28
  55. Andrew Dessler Says:

    Holy cow! I hadn’t realized everything George Bush is doing for the environment. He’s pretty much got that whole “global warming” thing whipped (Reductions in GHG intensity! That’s as good as actual emissions reductions, right?). I guess it’s time for me to invent and then hype another environmental catastrophe in order to insure continued funding.

  56. 29
  57. eduardo zorita Says:


    perhaps the connection between the Hockey-stick and climate policy that you are looking for is embodied
    in the recent Nature paper by Hegerl et al. (2006) where the authors try to estimate climate sensitivity from paleo-reconstructions. Depending on which reconstruction you focus, this parameter looks quite different.
    Of course, there have been other lines sof research of estimating climate sensitvity but millennium climate reconstructions were expected to help reduce uncertainties here.

  58. 30
  59. hans von Storch Says:

    Our group (Eduardo Zorita, Fidel Gonzalez-Rouco and myself) have issued this statement: “We welcome the National Research Council’s Report, which clarifies that the discussion about the technical qualities of the hockeystick-methodology is insignificant for the overall conclusion that the presently ongoing warming is likely related to elevated greenhouse gas concentrations in the atmosphere. We are pleased to read that the NRC shares our view that the methodology behind the hockeystick is questionable. We stick to our view that the methodology was not sufficiently described when published and independently tested thereafter.” On my web-page (http://w3g.gkss.de/staff/storch/Media/NRC-conclusion.hvs+ez.0606.doc) this statement is explained in some more detail.
    The problem of “detecting” ongoing climate change as (partly) non-natural and “attributing” human causes to this change, is based on the speed of temperature change, i.e, it is mainly an analysis of trends. To this end, the hockey stick was never really relevant, but it was “made” relevant by interested scientists, often detached from the debate about “d&a” (detection and attribution) and the public, who is unable to deal with the intricacies of d&a.
    The analysis in Rybski, D., A. Bunde, S. Havlin, and H. von Storch, 2006: Long-term persistence in climate and the detection problem. Geophys. Res. Lett. 33, L06718, doi:10.1029/2005GL02559 examines how the detection effort depends on what we assume the right historical temp reconstruction would be. That is the most recent trend from instrumental data were compared with “historical noise levels” from a series of reconstructions, namely Mann, McIntyre, Esper, Jones and Moberg. In all cases, the result was the same – independently of the assumed temp history of the last 1000 years, the recent changes are beyond the range of historical “evidence” (whichever you chose to opt for).
    In my opinion, the significance of the hockeystick debate is not with the question of d&a, but with the scientific culture of openly discussing concepts, of sharing data, of describing methodologies so that third parties, also hostile third parties, can examine the claims.

  60. 31
  61. Indur Goklany Says:

    The precise statement in the IPCC TAR Summary for Policy Makers stated the following (footnotes omitted):

    “New analyses of proxy data for the Northern Hemisphere indicate that the increase in temperature in the 20th century is likely to have been the largest of any century during the past 1,000 years. It is also likely that, in the Northern Hemisphere, the 1990s was the warmest decade and 1998 the warmest year (Figure 1b). Because less data are available, less is known about annual averages prior to 1,000 years before present and for conditions prevailing in most of the Southern Hemisphere prior to 1861.”

    It seeme to me that in light of the NAS report’s Exec Summary that would have had to be modified thus:

    “New analyses of proxy data for the GLOBE indicate that IT IS PLAUSIBLE THAT the increase in temperature in the 20th century is the largest of any century during the past 400 years. It is also PLAUSIBLE that the 1990s was the warmest decade and 1998 POSSIBLY the warmest year. Because less data are available, less is known about annual averages prior to 400 years before present.” [NEW TEXT IN CAPS, EXCEPT FOR THE "400". UNFORTUNATELY DELETIONS NOT SHOWN.]

    To me, the latter statement is a lot less definitive, and much less compelling although it does extend the area of coverage from the NH to the globe. I say this because of the shorter time span, the fact that by 1600 the world had already slipped into the Little Ice Age, and the world of difference between “likely” and “plausible”.

  62. 32
  63. per Says:

    “agreed that the HS debate wasn’t relevant to climate policy, but was relevant to some questions of research policy. The NRC seems to agree. So while you may think that the HS debate is climate policy relevant, I don’t see it.”
    Dear roger
    the HS debate is not about our models of global climate; so everyone can agree. But our models of global climate are very difficult to test empirically.
    If it were to transpire that there is large scale and routine variation in global temperatures “naturally”, then the factors that control this would have to be built in to global climate models. You would have to be able to exclude natural causes of temperature rise, to prove anthropogenic; you would have to know what the basis of natural variation is as a fundamental. It is not clear that this fundamental would be satisfied.

  64. 33
  65. per Says:

    “So while you may think that the HS debate is climate policy relevant, I don’t see it.”
    if you truly think so, why did you write
    “this NAS report will allow the rest of us to focus on the policy debate rather than this particular issue of science” ?
    if the HS report was so irrelevant, then the outcome of the report (near-vindication according to you) must have been completely irrelevant anyway ?
    from page 103 of the NAS report:
    “Current climate models have been tuned to optimize their ability to simulate the present
    climate and exhibit a range of climate sensitivities associated with different treatments of processes such as those associated with clouds and snow and ice (Webb et al. 2006, Winton 2006).”
    So even the NAS panel seems to think that calibrating models against temperature history is kind of important.

  66. 34
  67. Roger Pielke, Jr. Says:


    Thanks much for this context. According to at least several of the NRC committee “plausible” = “likely” (as defined by IPCC). But if this is indeed a main point of the report, I’ll stand by my initial reactions!

    Your edited IPCC paragraph should be viewed as a lesson in the fine line between selling and overselling science.


  68. 35
  69. Roger Pielke, Jr. Says:

    Hans- Thanks for sharing this statement. I agree with you 100% when you write: “The significance of the hockeystick debate is not with the question of d&a, but with the scientific culture of openly discussing concepts, of sharing data, of describing methodologies so that third parties, also hostile third parties, can examine the claims.”

    However, some clearly want to make it an issue of D&A [detection and attribution].

    It does raise very interesting science policy questions.

  70. 36
  71. Roger Pielke, Jr. Says:


    Thanks much. However, I am not optimistic that unceratinties about the distant climate future can be reduced, or if they can, how certain we can actually be. SO from a policy perspective, I am already sold on the notion that deicsions must be made under fundamental uncertainty. This need not precluse effective climate policies.


  72. 37
  73. Roger Pielke, Jr. Says:

    Thanks for these further comments. You write: “if the HS report was so irrelevant, then the outcome of the report (near-vindication according to you) must have been completely irrelevant anyway ?”

    Exactly, with respect to cimate policy. See Hans von Storch’s comments on this thread.

    From the standpoint of climate science policy issues, the report is more relevant, however, the committee did not engage these issues.


  74. 38
  75. Steve Hemphill Says:

    Too much apples and oranges on this. Was MBH98 science or alarmism – that’s the question. The fact a site was set up to defend alarmism, and the simplistic explanations and censoring of posts evident there are surely consistent with shoddy “science”. – somebody has an agenda. Could it be the “Oil for Food” guys????

    One would think the UN would want to heavily investigate the potential for increased food supply from enhanced flora food in the atmosphere, instead of just dismissing the possibility.

  76. 39
  77. per Says:

    “They report does acknowledge that there are perhaps greater uncertainties in temperature reconstructions, reducing Mann et al.’s claim of warmest decade/year in 1,000 years down to 400.”
    I also note that you didn’t attempt to justify your claim that this is a “near-complete vindication” of Mann’s work. Given that the NAS committee do not explicitly rely on Mann’s work for the 400 year claim, I would suggest that this is anything but vindication.

  78. 40
  79. KenGreen Says:

    I have to agree with those who’ve seen the recent NAS report as a repudiation of Mann’s work and the utility of the hockey stick. I think the summary has some very telling points.

    First, they expressed “very little confidence” that temperatures can be estimated prior to about 900 A.D. and “even less confidence” in claims made about the decade of the ‘90s, and the year 1998 in particular as having been the hottest in 1000 years. They do, however, suggest that there was indeed a medieval Warm Period around 1000 AD, and a Little Ice Age around 1700. That’s a serious crack at the hockey stick chart.

    Second, and I think more important from the standpoint of the public debate over climate change, is the fact that they admit such reconstructions are not of much use with regard to assigning attribution to people, observing that they are “not the primary evidence.” that humanity is causing climate change.

    Third, they stated at the briefing that Mann et al. under-represented the uncertainties relevant to the early proxies, and expressed the sentiment that the IPCC probably gave too much visibility to what was then a new, untested study.

    Finally, when asked at the briefing what they meant by “plausible,” they basically said that their research couldn’t say whether Mann’s full claim was or wasn’t correct beyond 400 years, but that it’s “plausible” simply because other climate dynamics suggest a linkage between GHG concentrations and temperature. I think this was simply a bone thrown to Mann et. al. (along with conspicuous avoidance of the names of Ross McKitrick or Steve McIntyre) so that he could save face, and claim that at least a major part of his original thesis was valid.

    As for the way the media is carrying this, I’m simply aghast at how badly some outlets are covering the issue, having *completely* missed the key finding of the NAS report, which is that you can say very little about the climate more than 400 years ago with any significant certainty. I think one of the guys at the press briefing (Cuffey) used the word “murky” more than a dozen times in that hour to refer to anything earlier than 1600 AD.


    Ken Green

  80. 41
  81. Carl Christensen Says:

    So now that it was all “much ado about nothing” — the “climateaudit cheerleaders” will screech that it’s spin, coverup, a conspiracy between all scientists, etc. We already see on the blogs that “climate-scientists-by-blogger-reputation-only” like Benny & “per” & Lubos are infuriated that their faux-contrarian right-wing views aren’t vindicated enough.

    I mean, really, was it worth all the invective, character assassination, attempts to ruin MBH’s reputations & careers just to whittle down that, at most, maybe the peak temps of the Medieval Warm Period were higher than the past decade?

  82. 42
  83. Benny Peiser Says:


    I did a google search today on the media coverage of the NAS report

    The spin and deceiptive headlines are staggering:

    Backing for ‘hockey stick’ graph
    BBC News, UK – 23 Jun 2006

    Prestigious scientific panel backs global-warming data
    Seattle Times, United States – 23 Jun 2006

    National panel supports ‘98 global warming evidence
    Boston Globe, United States – 23 Jun 2006

    US Panel Backs Data on Global Warming
    Los Angeles Times, CA – 23 Jun 2006

    US scientists back manmade warming claim
    Guardian Unlimited, UK – 22 Jun 2006

    Scientists believe world is at its hottest for 2,000 years
    Scotsman, United Kingdom – 22 Jun 2006

    Earth is hottest it’s been in 2,000 years, study says, and humans are to blame
    Canada.com, Canada – 22 Jun 2006

    Research: Earth Running a Slight Fever
    ABC News – 22 Jun 2006

    Science Panel Backs Study on Warming Climate
    New York Times, United States – 22 Jun 2006

    Earth Hottest It’s Been in 2,000 Years
    Forbes – 22 Jun 2006

    Earth has a ‘fever’
    Advertiser Adelaide, Australia – 22 Jun 2006

    Earth’s Temp May Be at 2,000-Year High
    ABC News – 22 Jun 2006

    Earth is hottest now in 2,000 years
    Ireland Online, Ireland – 22 Jun 2006

    Report backs global warming claims
    Boston Globe, United States – 22 Jun 2006

    Study: Earth is hottest now in 2,000 years; humans responsible for much of the warming
    USA Today – 22 Jun 2006

    Now, compare the cant listed above with the ingenuous WSJ headline: “PANEL STUDY FAILS TO SETTLE DEBATE ON PAST CLIMATES”

    It would appear that the Wall Street Journal is one of the few media outlets to have covered the NAS report in an even-handed manner (see below). No wonder that the interested public has been losing trust in global warming campaign journalism in much of the traditional media.


    The Wall Street Journal, 23 June 2006


    An expert panel called on to resolve a politically charged scientific debate said that the key conclusion of a widely cited study of past temperatures is “plausible” but not proved.

    The report by the 12-member committee of the National Research Council was prepared after a political fight broke out over the “hockey stick,” a reconstruction of past temperatures from tree rings, buried ice and other records.

    Far from resolving the debate, the panel’s findings yesterday drew widely different reactions among climate experts and on Capitol Hill, where the hockey-stick graphic has long been a lightning rod in the debate over global warming.

    The graphic, created in 1998 by climatologist Michael E. Mann and colleagues, gets its name from the rapid, blade-like rise of recent temperatures compared with past centuries. The hockey stick became a prominent scientific symbol after it appeared in an influential 2001 United Nations report. Citing the work of Dr. Mann and others, the U.N. concluded there was a 60% to 90% chance that temperatures in the 1990s had been the warmest since 1000, and that 1998 was the warmest single year.

    Panel chairman Gerald R. North, a climatologist at Texas A&M University, said his committee’s findings couldn’t support that claim. Dr. North said the limited data available on ancient climate means that scientists can say with high confidence only that the “last few decades” of the 20th century were the warmest period in the past 400 years, and with “less confidence” that they were the warmest in the past 900 years.

    Skeptics of global warming yesterday embraced the panel’s findings. Sen. James Inhofe, an Oklahoma Republican who has called global warming a “hoax” and is opposed to limits on greenhouse gases, said in a written statement that the report proved “the hockey stick is broken.”

    However, the study also noted that there was very little evidence to suggest that Dr. Mann’s claim wasn’t correct, leading others to take an opposite view. Roger Pielke Jr., head of the University of Colorado’s Center for Science and Technology Policy Research, called the study a “near-complete vindication” of Dr. Mann’s work and reputation.

    Thermometer measurements have shown a more than one-degree rise in temperature over the past century, and the rise has been linked by other research to man-made greenhouse gases, primarily the carbon dioxide produced by burning coal or gasoline.

    Scientists predict the planet will warm between two and more than 10 degrees more this century, a development that many fear will prove disastrous.

    Some skeptics think the danger of global warming is overstated. The hockey stick became a special focus of criticism after an amateur Canadian mathematician and petroleum consultant, Stephen McIntyre, published articles charging serious flaws in the work.

    Texas Rep. Joe Barton, the Republican head of the House Energy and Commerce Committee, launched a probe of the hockey stick last July. That probe is continuing, according to the committee.

    Mr. Barton’s investigation drew criticism from scientific groups, as well as fellow Rep. Sherwood Boehlert (R., N.Y.), who called on the National Research Council, a private, nonpartisan advisory group, to carry out the study published yesterday.

    Mr. Boehlert said the report shows scientists still have work to do understanding ancient temperatures. “Congress ought to let them go about that work without political interference,” he said in a prepared statement.

  84. 43
  85. Bernd Stroeher Says:


    As Mann’s hockey stick methodology is to a great deal statistics, other scientists, like economics, will be able to enter the discussion and to evaluate the results of the North Panel and surely will be surprised how data are used and handled in some parts of climate science.

    What Barton will think when he reads Von Storch’s co-author” Eduardo Zorita’s comment on McIntyre’s web-side : Hopefully he will call his specialists on statistics and will ask them “what critical position is right , not only possible”.

    Zorita’s comment

    Eduardo Zorita’s take posted up below was:
    in my opinion the Panel adopted the most critical position to MBH nowadays possible. I agree with you that it is in many parts ambivalent and some parts are inconsistent with others. It would have been unrealistic to expect a report with a summary stating that MBH98 and MBH99 were wrong (and therefore the IPC TAR had serious problems) when the Fourth Report is in the making. I was indeed surprised by the extensive and deep criticism of the MBH methodology in Chapters 9 and 11 .

    Bernd Ströher

  86. 44
  87. Francois Ouellette Says:


    It is hard to agree with you that “this is a near-complete vindication of Mann’s work”, especially after the release of the Wegman report. Quite the contrary, the Wegman report combined with the NAS report are a complete vindication of Steve McIntyre’s work.

    Now you may retreat behind the claim that this has no policy implications, but the implications are very serious. In this debate, the policy choices are based on the scientific findings. If the scientific process has been hijacked by a “clique” of scientists with an ideological bias, then clearly the policy makers will not have access to all the relevant information.

    There are by now many indications that the IPCC process, behind its veil of openness and objectivity, is basically flawed. The frantic search for a “consensus” inevitably means that dissident views are hidden under the rug. Scientists do not normally seek for a consensus. The consensus that emerges time and time again in the scientific practice is a state of fact, when competing theories run short of arguments, but that can take many years, decades or even centuries (e.g. darwinism). Furthermore, a scientific consensus is never a “hard” one, as some would like it to be. The science is never “settled” as is often proclaimed in the global warming debate. The scientific consensus, whenever it occurs, is a soft one. It can be reversed overnight by new and significant results. But for that to happen, dissident views must have enough room to be heard, especially in the peer reviewed litterature, but also must be able to find support from grant agencies.

    The hijacking of the climate debate by a group of ideologically biased scientists à la Jim Hansen or Michael Mann has meant that it is very difficult for competing theories to be heard. The acrimonious politicization of the debate serves the ideologists on both sides, who inevitably use it to question the political motives of competing, but scientifically honest, research. Objective science loses on all counts, and so do policy makers.

    Roger, you have read the NAS report from a non-scientist point of view, and have missed its true significance. Can’t you read between the lines? The NAS panel was composed of climatologists who were themselves too intimidated to openly criticize members of their own community. But a careful reading of the whole report shows clearly how they all had to agree with Steve McIntyre’s analysis. It’s in there for all to read, and no doubt the scientists involved will have understood, as shown by Drs. Zorita and Von Storch’s reaction. The Wegman committee is composed of statisticians, who are independent of that community, and their assessment is far more objective, and quite blunt. But to me both reports say the same thing about the science.

    This may be a turning point in the debate. Turning points are not always obvious, and are only recognized in hindsight. But what Steve McIntyre has accomplished, and only a total outsider like him could do it, is to expose the weakness of the scientific process that has so far guided the policy debate. If the hockey stick was poorly audited, what can be said of the rest of the IPCC report? There is a clear need to reassess the way policy makers get their facts from the scientific community. The demand for a consensus doesn’t work: it just reinforces biases. Should we look more closely at the idea of a “scientific court”, where both sides are exposed to an panel of “independent” judges? Maybe. But one way or another, climate science has to find a way out of this political polarization, and regain the serenity required for real scientific progress.


    François Ouellette

  88. 45
  89. Mark Bahner Says:

    Hi Francois,

    You write, concerning the NAS report, “It is hard to agree with you that ‘this is a near-complete vindication of Mann’s work’,…”

    Yes, I was extremely surprised to see that quote attributed to Roger. I thought he must have been misquoted…but apparently not. I don’t see how a report that observes that this is the warmest time since 1600 (the start of the “Little Ice Age”), and that it’s “plausible” that this is the warmest time in the last 1000 years, constitutes a “near-complete vindication.”

    You also write, “Now you may retreat behind the claim that this has no policy implications, but the implications are very serious. In this debate, the policy choices are based on the scientific findings.”

    However, there is something much larger that clearly *does* have policy implications: that is the “projections” in the IPCC TAR (e.g. “1.4 to 5.8 degrees Celsius warming” from 1990 to 2100).

    The IPCC TAR (Third Assessment Report) “projections” are completely pseudoscientific nonsense. In fact, the IPCC itself acknowledges this to be so, when they write in the IPCC TAR:

    “Scenarios are images of the future or alternative futures. They are neither predictions nor forecasts.”

    If the IPCC TAR scenarios are NOT “predictions or forecasts” then they can NOT be falsified (shown to be incorrect) by future events.

    An absolutely bedrock foundation of science is that it involves FALSIFIABLE predictions of future events.

    It’s remarkable to me that Roger Pielke Jr. has never really explored this issue…instead seemingly accepting the “1.4 to 5.8 degrees Celsius” range as somehow valid. It clearly is not!


    P.S. I wonder how in the world Roger Pielke Jr. can give his upcoming Congressional testimony on “Climate Change: Understanding the Degree of the Problem”…without addressing the massive and blatant scientific fraud in the IPCC TAR “projections”?