11 Ammann Mentions in Mann's Barton Letter

As I was writing up my note on Ammann at AGU, I re-read Mann’s reply to Barton, which mentions "ammann" no fewer than 11 times, usually as an "independent"
scientist confirming his results. I’ve collected the mentions here, which make for some merry reading. Then I’ll discuss exactly how "independent" Caspar Michael Ammann (should we call him C. Michael Ammann?) is of his realclimate associates – his former mentor Bradley and his frequent coauthor and collaborator, Mann.

Here’s a typical statement by Mann:

As a result of our willingness to share our research with others, an independent team of scientists has used the research data my colleagues and I have made public to replicate our research and confirm the reliability of our findings. See Wahl, E.R., Ammann, C.M., Robustness of the Mann, Bradley, Hughes Reconstruction of Surface Temperatures: Examination of Criticisms Based on the Nature and Processing of Proxy Climate Evidence, Climate Change (2005) (forthcoming) and associated website: http://www.cgd.edu/ccr/ammann/millennium/MBH_reevaluation.html.

Their "willingness to share research" – give me a break. Here are other "ammann" mentions in the letter:

Moreover, independently-derived source codes for implementing our algorithm, and all required input data, have been posted on the website of the National Center for Atmospheric Research. See http://www.ucar.edu/ccr/ammann/millennium/CODES_MBH.html…

an independent group has replicated our original methods and results (See Wahl, E.R. and Ammann, C.M., Robustness of the Mann, Bradley, Hughes Reconstruction of Surface Temperatures: Examination of Criticisms Based on the Nature and Processing of Proxy Climate Evidence, Climatic Change (2005) (forthcoming)).

The various claims of McIntyre and McKitrick “including the ones repeated in your question ” have been exhaustively examined by two different groups of climate researchers who have found their objections to be unfounded.(5) See also National Center for Atmospheric Research, Media Advisory: The Hockey Stick Controversy New Analysis Reproduces Graph of Late 20th Century Temperature Rise (May 11, 2005) (available at: http://www.ucar.edu/news/releases/2005/ammann.shtml).

(5) See, e.g., Rutherford, S., Mann, M.E., Osborn, T.J., Bradley, R.S., Briffa, K.R., Hughes, M.K., Jones, P.D., Proxy-based Northern Hemisphere Surface Temperature Reconstructions: Sensitivity to Methodology, Predictor Network, Target Season and Target Domain, Journal of Climate (2005) (in press, to appear in July issue); Wahl, E.R. and Ammann, C.M., Robustness of the Mann, Bradley, Hughes Reconstruction of Surface Temperatures: Examination of Criticisms Based on the Nature and Processing of Proxy Climate Evidence, Climatic Change (2005) (forthcoming).

Our conclusions have been confirmed by Wahl and Ammann (see above).

Moreover, Wahl and Ammann demonstrate that the climatologically improbable results obtained by McIntyre and McKitrick, which would suggest that the Northern Hemisphere was unusually warm during the 15th century (the middle of the so-called “Little Ice Age”), are statistically meaningless, and an artifact of both their exclusion of key proxy data (as discussed above) and the use of a flawed implementation of the Mann et al. 1998 method. See http://www.cgd.ucar.edu/ccr/ammann/millennium/CODES_MBH.html ) (chart at the bottom of the page). …

As noted above, in contrast to the work of Mann et al. 1998, the results of the McIntyre and McKitrick analyses fail verification tests using the accepted metric RE. This is a key finding of the Wahl and Ammann study cited above. It is for these reasons that Wahl and Ammann have concluded that McIntyre and McKitrick’s results are “without statistical and climatological merit.”

The European Geophysical Union wrote to the Barton Committee also citing Ammann and Wahl:

the results of the study by Mann et al. (1998) have been confirmed by an independent team of scientists with freely available computer code and data (Ammann and Wahl, 2005). http://www.ucar.edu/news/releases/2005/ammann.shtml

Let’s now look at Ammann’s connections with Bradley and Mann to see exactly how "independent" he is of these two men.

First, all three are co-proprietors of realclimate.org.

Second, Ammann’s c.v. (not up-to-date) shows that he studied under Ray Bradley for over 5 years at the Univesity of Massachusetts.

January 1997-2002 : University of Massachusetts, Department of Geosciences, Ph.D. program in Paleoclimatology with R.S. Bradley

His c.v. lists his experience as including associations with Bradley and Mann as follows:

Experience: Research Assistant Univ. of Massachusetts, Department of Geosciences with Raymond S. Bradley: Modeling of climate impact of explosive Volcanism. Further interaction with: M.E. Mann (Paleoclimate Reconstruction), J. Brigham-Grette (Quaternary Geology), M. Leckie (ODP), W.D. McCoy (Loess), M. Abbott (Paleolimnology) and E.A. CoBabe (Biogeochemistry) (1997-present).

His team/collaborators at UCAR are said to include Mann:

Team/Collaborators: E. Wahl, C. Ammann (NCAR), N. Graham (Scripps and HRC), D. Nychka (NCAR), M.E. Mann (University of Virginia)

While this supposedly "independent" work was being done in 2005, Ammann and Wahl were co-authoring with Mann the following publication for Journal of Climate:

Mann, M.E., Rutherford, S., Wahl, E. and Ammann, C., 2005, Testing the Fidelity of Methods Used in Proxy-Based Reconstructions of Past Climate, Journal of Climate.

as well as collaborating with Bradley on the following:

Ammann, C. M., J. T. Kiehl, C. S. Zender, B. L. Otto-Bliesner, and R. S. Bradley (2005), Coupled simulations of the 20th century including external forcing, In Press in Journal of Climate.

In the development of their code, they were not dealing just with the public record as Wahl and Ammann also noted in one of their articles that:

Dr. Mann also answered clarifying questions concerning a few details of the method.

Previous coauthorships between Ammann and Mann and/or Bradley include the following:

Ammann C.M., M.E. Mann and R.S. Bradley, 1999: Explosive Volcanism and ENSO: Search for a Relationship in a Multicentury Global Climate Reconstruction. EOS, Transactions, Vol. 80, No. 46, supplement, AGU 1999 Fall Meeting, F220
Ammann C.M., B.L. Otto-Bliesner, J.T. Kiehl and R.S. Bradley, 2002: Krakatau 1883: Problems with the "Reference Eruption". Chapman Conference, Volcanism and Climate, Santorini, June 17-21 2002. A. Robock (Convener).
Mann, M., Ammann, C., Bradley, R., Briffa, K., Jones, P., Osborn, T., Crowley, T., Hughes, M., Oppenheimer, M. and others, 2003 “On past temperatures and anomalous late-20th century warmth.” EOS 84, 256-257
Mann, M., Ammann, C., Bradley, R., Briffa, K., Jones, P., Osborn, T. and others., 2003 “Response to Soon et al’s comment on ‘On past temperatures and anomalous late-20th century warmth’.” EOS 84, 473-474
Adams J.B., M.E. Mann, C.M. Ammann, 2003: Proxy evidence for an El NiàƒⰯ-like response to volcanic forcing. Nature, 426, 274-278.

As I’ve mentioned before, one of the most extraordinary things about the Ammann-Wahl emulation of MBH98 is that it’s pretty much identical to ours. I reconcile our results and Ammann-Wahl to 9 digits; neither of us "exactly" replicate MBH, although both of us can reproduce the main features. It’s interesting to see that Mann, in his testimony, unlike Houghton, did not mention the GRL article, just the Climatic Change article, which was then under review. (I don’t know its status). So Mann undoubtedly had been informed of the rejection of the GRL article and was careful not to mention it.

Anyway, Ammann is obviously not "independent" of Bradley or Mann and any study by Ammann and Wahl, regardless of its merits, is not an "independent" study, contrary to the evidence of Mann to the House Energy and Commerce Committee.


  1. Kenneth Blumenfeld
    Posted Jan 14, 2006 at 12:57 AM | Permalink


    I think you might want to clarify what you think Mann meant when he said “independent,” and contrast that with what you assume the term to mean. I expect you will find some differences there. From my view, I see two different definitions.

  2. Paul
    Posted Jan 14, 2006 at 3:28 AM | Permalink

    We never hear from Hughes on all this. What is his view?

  3. Posted Jan 14, 2006 at 10:12 AM | Permalink


    That’s quite a funny reply (I mean, the Mann letter). I can’t imagine why he wouldn’t disclose the source code, especially in view of the controversy. I understand the Intellectual Property argument, but can this kind of software have any sort of commercial value? If not, what does he lose by making it public? On the other hand, refusing to release it just makes the whole thing look even more suspicious. I’ve written many pieces of software in my scientific carreer, and I can’t think of one that I would not have made public if someone had asked (nobody ever asked…well, I’m a lousy programmer).

    I also don’t like his personal attacks. This is not a way to defend science. To counter your arguments by saying that you have no training in climatology is absurd, because this is all about statistics. The call to the “overwhelming consensus” is also a very weak argument, as always. And finally, you’re absolutely right that former graduate students are not “independent”, especially if they have co-authored papers in the recent past.

    Unfortunately for me, I can’t really understand the debate yet, not knowing enough about RE and R2 in this context to judge who is right and who is wrong, and I doubt rep. Barton can understand that either. A really fair and independent assessement would compare the results from both methods, and objectively analyze the pros and cons (I’m sure this is not a black and white issue). I don’t see why this causes such a fuss.

  4. Steve McIntyre
    Posted Jan 14, 2006 at 11:04 AM | Permalink

    #3. Francois, I don’t think that Mann even has clear title to the code. Surely it belongs to the applicable university and Mann has, in law, “converted” the code by claiming it as his own property. I’ve read a lot of the source cases on conversion torts in connection with a legal dispute – don’t get me going on that – look at my post on the topic, it’s amusing.

    My training in mathematics and statistics is obviously adequate for what I’m doing and both are relevant disciplines. I’d even submit that something as simple as accounting is relevant to multiproxy studies – as many problems in MBH are more like sharp accounting – and experience in busienss accounting is highly relevant to the study. This is something that many people don’t understand.

    As to RE and R2, if you read Barton carefully, they are dealing entirely with disclosure matters – this can be dealt with independently of the statistics – and are within the range of lawyers. Their questions are very measured and have been misunderstood and mischaracterized.

    I don’t understand the climate science hysteria at all. At some point, they have to convince people like Barton and, in their shoes, I’d welcome any oportunity to have an audience with adversaries rather than contenting myself with warm fuzzies from the like minded.

  5. Brooks Hurd
    Posted Jan 14, 2006 at 3:49 PM | Permalink


    In Hockey speak, the term “indepenent”, as defined by their usage of the term, is simply someone other than the authors of a paper. I had always thought that in science “independent” meant a disinterested third party. I guess that I am wrong.

  6. Steve McIntyre
    Posted Aug 7, 2008 at 4:05 PM | Permalink


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