National Post: Re-visiting the Stick

I have a lengthy op ed in today’s National Post go here summarizing some of the debate since publication of our 2005 articles. The article is on page FP19. Update: The link is now offline. Here is the text as I submitted it to National Post; it may differ a little, but not much.

The much-vaunted “hockey stick diagram” became famous a few years ago when the Intergovernmental Panel on Climate Change (IPCC) used it to argue that the “1990s were the warmest decade in the millennium and 1998 the warmest year”. These sound bites were used in speeches advocating Kyoto; the Government of Canada promoted the “hockey stick” interpretation of temperature history on its web site, sent it to schools across the country and quoted its conclusion in pamphlets mailed out to all Canadians.

The “hockey stick” theory overturned the view in the first IPCC report that there had been at least equivalent warmth in the “Medieval Warm Period”, when, for example, Vikings had settled in Greenland. Recently, it has been reported that one of the leading scientists in the field wanted to “get rid of the Medieval Warm Period”. The hockey stick was how they did it. Quite apart from the MWP, climate during most of geological history was warmer than at present.

In two peer-reviewed articles published this past winter, Ross McKitrick and I showed that there had been no due diligence on the hockey stick calculations by the IPCC and that there were serious problems in the calculations. Our main article was published in the same scientific journal that published the hockey stick graph used by the IPCC

What has been the public reaction? The story has been reported around the world. Coverage began in the National Post and the Dutch science magazine Natuurwetenschap & Techniek. Since then articles have appeared in, among others, Nature, Science, The Economist, and a front page feature (Feb 14) in The Wall Street Journal. The story has been reported on the BBC and Global, as well as German and Dutch television. My website has received over 250,000 hits since mid-February.

What has been the reaction from climate scientists? It varies.

Richard Muller of Berkeley likened our contribution to removing a piece of a jigsaw puzzle that was in the wrong place so that investigation about climate history can resume with a clean slate. Hans von Storch, a famous German climate scientist, said that Mann’s error was material, that it was “good that debate about the temperature history of the last millenium can be resumed again without reservations”, and that we are entitled to “thanks” for this contribution. On the other hand, Andrew Weaver of the University of Victoria, a prominent Canadian climate scientist, said that our original paper should have been “rejected” and that he believed that giving equal space to both sides in a dispute can be dangerous, particularly when applied to scientific matters.

One claim has been pretty well universally accepted: we showed that an unreported step in the Mann calculations mines datasets for hockey-stick shaped series. We showed that we could produce hockey sticks even from random data. This observation has been verified by others and we would say that this claim is not argued by anyone other than perhaps the original authors.

What of our other main claims?

We showed that this obviously unsatisfactory statistical method had really bad results on actual data as well: we showed that the bad method mined for bad data creating a “perfect storm”. It turned out that their results depended on the inclusion of a controversial set of US bristlecone pine tree ring series, which had a hockey stick shape. However, the specialists who studied bristlecones had explicitly stated that the hockey stick shape was not due to temperature, but to fertilization. We showed that the original authors had known their results fell apart with the removal of these series and that they had not only failed to disclose these adverse results, but claimed the opposite in a later commentary on their own work.

We also showed that the original authors withheld vital data (certain verification statistics), which showed their conclusions were statistically insignificant, and that the procedure for benchmarking the one verification statistic that they did report was incorrect.

To date, none of these claims has been challenged. This is not to say that these claims have been accepted or that our work has not been challenged. There has been a concerted effort by climate scientists to show that the errors in the hockey stick calculations “do not matter”. In fact, there has been much more effort by climate scientists to try and disprove our results than ever went into checking the original hockey stick. We made the process easy by publishing all our computer code, unlike the hockey stick authors who still refuse to release theirs even seven years after the original publication. They told the Wall Street Journal that to show the code they used to produce their results would be “giving in to intimidation.”

We know of 5 submissions thus far to academic journals commenting on our most recent results (in addition to 2 submissions last year on our 2003 results). In the United States, the mere submission of two papers criticizing our results prompted the University Corporation for Atmospheric Research (UCAR), a prominent, federally-funded institution that receives hundreds of millions of dollars for climate research to issue a nation-wide press release declaring our work is without merit. One of the two papers was shortly thereafter rejected by the journal (the other is still undergoing review), but the original press release remains on the UCAR web site. Coincidentally, the journal Nature recently attacked the use of press releases to announce research results before they are accepted at journals. They denounced the practice in the case of stem cell research, but did not criticise the UCAR.

Without getting into particulars beyond what has been publicly disclosed, none of them actually contest any of our specific findings. None dispute the nature of the undisclosed computational step. None contest the unacceptable dependence of the results on the bristlecone pines; none try to argue that bristlecone series are a valid “proxy” for temperature history. None address the failure of the hockey stick to pass simple verification tests.

One style of comment does not test the impact of the erroneous method on the hockey stick itself but on completely different data sets or on unrelated computational problems. Our reply to these responses is more or less: So what?” As far as we can see, the only place to test the impact of errors in the hockey stick method is on the calculation of the actual hockey stick.

Another type of response is to show that a hockey stick can be produced even without the erroneous method by, for instance, increasing the number of principal components used to represent the North American tree ring network. But every such permutation that we have seen boils down to a back-door method of allowing the bristlecone series to dominate the final results. Once you know of the role of these defective proxies in the hockey stick, you can’t simply ignore them. But this is what is being attempted. Further, these salvage attempts fail common statistical verification tests. However, in every example that we have seen this information is withheld from the reader (as it was in the original article). This is the case for the papers cited in the UCAR press release, for example.

A third type of response has been to mischaracterize our work. As Muller and others have clearly understood and as we have explained on many occasions, our work to date has been entirely critical. We are not advocating our own reconstruction of climate. We are simply arguing against “flawed intelligence” which is not backed by the data. If this re-opens debate for other interpretations, including those held by the IPCC in the pre-Mann era, then that would be a welcome outcome.

What has been the reaction from the government and IPCC? Not once have we been contacted by Environment Canada or any other Canadian government ministry dealing with climate research to discuss our work. I had contacted Canada’s Chief Climate Science Advisor during Kyoto negotiations (Henry Hengeveld) last fall and took him to lunch to explain our work. He shrugged it off and never followed up. Environment Canada has a comment on their website dismissing our work, based only on a claim by the original authors that the errors did not matter. A reader from Manitoba forwarded to us an email from Environment Canada responding to his question about why they still promote the hockey stick. Apparently they have dismissed our research on the basis of some unpublished and fallacious commentary they found on the internet, without ever asking for our input. We have had no contact from IPCC either.

Our efforts to promote the concept of auditing important climate studies prior to usage in public policy is getting increased attention. We have learned that people have the wrong idea about journal peer review. Users of scientific research for policymaking generally assume that when an article is published in a peer-reviewed journal it means that someone checked the data, checked the calculations and checked that the stated conclusions are supported by the evidence presented. But peer review does not guarantee any of this. Influential papers in climate research can go for years without the data or methods even being disclosed, let alone independently checked, even as huge policy investments are made based on them. So we have urged policymakers to put in place formal processes to ensure complete disclosure of data and methods for any scientific work that is being used to drive policy debates. We urge the development of audit procedures to verify compliance with such requirements. We believe such innovations would be good for science and good for the policymaking process, even if a few more scientific icons get broken as a result.

One of the first places that we would recommend such procedures is the temperature data set used by the IPCC. Other researchers have tried without success to get access to the supporting data. One of them shared with us the response he received from the principal author of the dataset: “We have 25 years invested in this work. Why should we let you look at it, when your only objective is to find fault with it?”


  1. Posted Jun 17, 2005 at 8:26 AM | Permalink | Reply

    … or you could just go here.

    Steve: Thanks for this. I’ve edited the post to use your link.

  2. Posted Jun 17, 2005 at 9:06 AM | Permalink | Reply

    In some computers (mine, at least) the National Post page does not fit nor read very well. I’ve tried another link and it works:

    By the way, very interesting and informing article, and very indicative of how (bad) scientific discussions go these days.

  3. Peter Hartley
    Posted Jun 17, 2005 at 3:06 PM | Permalink | Reply

    At least Environment Canada feels the need to discuss your work. I just noticed the following US Government site

    that presents the Mann-handled data without comment.

  4. Doug L
    Posted Jun 17, 2005 at 4:15 PM | Permalink | Reply

    No doubt the hockey stick graph is a poorly conceieved thing from a scientific point of view. So why might it not matter?

    Could at be that what they are arguing about lately on RealClimate be what matters? They are discussing bets about the projections. How much affect does the hockey stick graph have on the projections?

  5. John A
    Posted Jun 17, 2005 at 5:29 PM | Permalink | Reply

    …and the response will be “ignore McIntyre and he will go away”.

    Great article.

  6. Ed Snack
    Posted Jun 17, 2005 at 6:20 PM | Permalink | Reply

    Excellent article, sadly it is unlikely to gain wide publication. John A has hit the mark, the tactic now seems to be to attempt to just ignore the inconvenient facts and stick with the fabrications.

  7. John A
    Posted Jun 17, 2005 at 8:04 PM | Permalink | Reply

    Re: #4

    But Doug, they are calibrating their models using the Hockey stick as a baseline. That’s the problem.

  8. Posted Jun 17, 2005 at 10:39 PM | Permalink | Reply

    A great response to the “smoking gun” article in USA Today a few days ago!

  9. Louis Hissink
    Posted Jun 18, 2005 at 4:52 AM | Permalink | Reply


    Good op-ed.

    Hang in.

  10. Doug L
    Posted Jun 18, 2005 at 10:07 AM | Permalink | Reply

    Re: #7

    John A,

    I’m a little surprised the Hockey stick graph is an important factor in the projections. It would be interesting to see exactly in the TAR where it is used as the baseline so that its importance can be gauged.

    Is it possible to see if the position of this baseline affects the slope of the projections? Are they concealing this? Perhaps there’s a way to come up with a graph to show how much the hockey stick graph is distorting the picture.

    Perhaps such a graph could get cool name, Anti-Hockey Stick Graph? Misconduct Penalty Graph? Slashing Cross Checking Graph? Hmmm. Cross Checking, Auditing get it?

  11. Doug L
    Posted Jun 18, 2005 at 11:54 AM | Permalink | Reply

    More Anti Hockey Stick Graph Name Ideas:

    Perhaps a series of graphs is needed, you could start out with a complex “Drawing Blood Graph”, simplify things with a “Two (or three) Line Pass Graph”, or a “Pulling the Goalie Graph”, then throw in the “Cross Checking Graph” and maybe the “Ten Year Misconduct Penalty Graph”, the knockout punch could be delivered with an “Icing on the Cake Graph”.

  12. Roger Bell
    Posted Jun 18, 2005 at 12:07 PM | Permalink | Reply

    There have been a number of issues about “global warming” discussed in the Washington Post recently. Blair has been trying to pressure Bush into signing the Kyoto Treaty and has also tried to enlist US Senators in helping with this. There have also been complaints that someone in the White House has been “diluting” reports about global warming. I sent email to Fred Hiatt(, who has responsibility for the editorial page, complaining about the discussion of global warming. I said that the science was by no means settled, and discussed your work with Ross on the Hockey Stick. He said that he would look into it.
    Steve,I’m sure you know the Post is regarded as being a pretty significant paper , not least because of the city it is published in, and so I wondered if you would be interested in contacting Fred Hiatt with a view to writing an article for it? Would it be possible for you to send him a copy of the article you wrote for the National Post as an example of your science?
    Another newspaper which might be interested is the Daily Telegraph, at least one of whose correspondents took umbrage about the stupid remarks made about “global warming” by Royal Society luminaries.
    All best
    Roger Bell

  13. Roger Bell
    Posted Jun 18, 2005 at 3:53 PM | Permalink | Reply

    Re #10,
    The hockey stick of Mann et al. is THE GRAPH as far as the IPCC is concerned. Ross McKitrick has a splendid article about this -see his talk at the Canberra meeting of sceptics – see Ross says that the hockey stick diagram appears 6 times in the 2001 IPCC Third Assessment Report. The report writers feel obliged to mention the weather satellite data , which doesn’t have the shape of the Hockey Stick. So they show this tropospheric data in a small diagram in black and white while the hockey stick is shown as a BIG diagram in COLOUR etc etc. It is pure deceit.

  14. Doug L
    Posted Jun 19, 2005 at 9:36 AM | Permalink | Reply

    Re: # 13

    Roger Bell,

    Figure 9 of the TAR shows greenhouse gas having a positive forcing of over 2W/m squared. I’m no scientist and have trouble seeing how this is affected by the hockey stick graph. None the less, I am highly skeptical of alarmist projections as the same table shows a large negative forcing by aerosols of similar magnitude.

    Previously I mentioned some ideas for anti hockey stick graphs. Since then, I became “carried away” and found a way to elaborate on what they might contain and placed it on a web page.

    There are no actual graphs but there are descriptions, it’s all done humorously, it lists the top ten reasons why climate scientists don’t want their funding pulled in the “Ten Year Misconduct Penalty Chart”, and how to construct a “Pull The Goalie Apart Chart”. The punchline is found on an “Icing the Puck” Video.

  15. Michael Jankowski
    Posted Jun 19, 2005 at 1:49 PM | Permalink | Reply

    Steve – are you allowed to give any details about the “rejected” paper criticizing your work?

  16. Ross McKitrick
    Posted Jun 20, 2005 at 8:17 AM | Permalink | Reply

    Re #10: You can see a graphical example of using the hockey stick as a baseline for global warming projections by going to the Summary of the IPCC Synthesis Report at Scroll down to page 34. Re #13, the appearances are Figures 2-20 and 2-21 in Chapter 2 of the Working Group 1 Assessment Report, Figure 1b in the Working Group 1 Summary for Policymakers, Figure 5 in the Technical Summary, and Figures 2-3 and 9-1B in the Synthesis Report.

  17. Doug L
    Posted Jun 20, 2005 at 12:02 PM | Permalink | Reply

    Re: #16
    Ross McKitrick,

    Thanks for the pointers to the figures. The hockey stick on the last page of the summary for policy makers does indeed show it used as a baseline for the projections. So perhaps it gives the projections a head start, also the trajectory at the end matches the trajectory of the projections. This gives the illusion of supporting the projections, so in effect giving our runner not only a head start, but a running start.

    Still, I would expect them to swear on a stack of Bibles that their projections don’t depend on the hockey stick. They’ve got all kinds of wiggle room here. They seem to have painted themselves into a corner, but it’s a big corner they can stand in for possibly decades, in my completely amaturish opinion.

  18. T J Olson
    Posted Jun 20, 2005 at 8:11 PM | Permalink | Reply

    A robust set of comments about this valuable restatement from readers.
    More alarming, of course, is how cirticism has been marginalized in a way that would have the late Karl Popper rolling in his grave! How have we come to this?

  19. Posted Jun 27, 2005 at 6:55 AM | Permalink | Reply

    Steve, the links to “Re-Visiting the Stick” don’t work. Please provide a good link as I would like to point some friends to it.

    Best regards, Ben

  20. Steve McIntyre
    Posted Jun 27, 2005 at 10:28 PM | Permalink | Reply

    Ben – as you see, I’ve inserted the text as I sent it to National Post. Steve

  21. TCO
    Posted Sep 19, 2005 at 9:44 PM | Permalink | Reply

    Maybe one good effect you all have had, has been more attention to methodology and sharing of code. Even as people battle to find fault in your work, they are digging into the issue of how choices in method affect answer and they are seeing your code is available and sharing their code in return.

  22. S.Sternhell
    Posted Dec 28, 2007 at 2:32 AM | Permalink | Reply

    Dear Steve,
    As a professional scientist and an academic of very long standing, I have always been conscious of the central role of integrity in all scientific research. Science is full of mistakes, misinterpretations, incompleteness and even plain stupidity. However, deliberately misleading work is as rare as it is reprehensible. I have noticed before that the global warming alarmists use data selectively or brush inconvenient facts (including basic spectroscopy) aside, but you seem to have produced the best piece of evidence so far for something more serious. In my opinion, the continuing use of the hockey stick after your demolition of it is even worse that its original introduction, which might have just possibly been an honest mistake. Just as bad, has been the disappearance of the hockey stick from bits of publicity (without affecting the conclusions) even though it formed a central plank of the alarmist’s case. How about revisiting the various “X hottest years since Y” claims – they strike me as prone to selective data mining.

  23. Posted Aug 24, 2008 at 7:54 PM | Permalink | Reply

    I agree with 22 S.Sternhell comments and point of view. Chris

  24. W.NICHOLSON ,brisbane
    Posted Sep 29, 2009 at 7:46 PM | Permalink | Reply

    As a non scientist I would be pleased to get the Global Surface Atmospheres annual temperature year by year from 1990 to 2009. Who would have these?
    When 7 day weather forcasts are often wrong I am lead to wonder the accuracy of predictions for 10 years or 100 years. Bill.N

  25. NancyN
    Posted Nov 5, 2009 at 7:37 PM | Permalink | Reply

    FYI, my daughter is enrolled in “Environmental Geology” [Fall 2009 class]. The book used is Geology and the Environment 5th ed. by Bernard Pipkin et al, copyright 2008. On page 333, the “hockey stick” is used in support of global warming.

Post a Comment

Required fields are marked *



Get every new post delivered to your Inbox.

Join 2,882 other followers

%d bloggers like this: