Overpeck’s “Hammer”

One of the curious aspects of IPCC peer review procedure is that the ultimate authority for accepting or rejecting comments by peer reviewers rests with the IPCC authors, as opposed to the Review Editors. Review Editors are supposed to see that authors respond to Review Comments, but don’t follow up to see that it’s actually done.

Here’s a strange example in the AR4 Medieval Warm Period Box – the one which Overpeck (483. 1105978592.txt) described in January 2005 as follows:

Hi all – attached is Keith’s MWP box w/ my edits. It reads just great – much like a big hammer. Nice job.

Overpeck liked the metaphor and in a June email (537. 1119924849.txt) talked of using the MWP Box “to hammer in one more nail” and again in July (550. 1121686753.txt) talked of “hammering home” their MWP message – language that caused even Briffa (551. 1121721126.txt) to worry about Overpeck’s intonations.

One of the blocks in Overpeck’s beloved MWP Box was Hughes and Diaz (1994), who had challenged the concept of a MWP early on. The MWP Box cited Hughes and Diaz 1994 favorably as follows:

A later study, based on examination of more quantitative evidence, in which efforts were made to control for accurate dating and specific temperature response, concluded that it was not possible to say anything other than “… in some areas of the Globe, for some part of the year, relatively warm conditions may have prevailed” (Hughes and Diaz, 1994).

However, there were some important issues about whether Hughes and Diaz 1994 actually proved their point – in particular, whether their tree ring chronologies preserved any centennial variance. Remarkably, Jan Esper and I, in our capacity as AR4 reviewers were in complete agreement on this point.

Esper commented on this language in the AR4 First Draft as follows:

6-1281 A 28:21 28:24 I guess, I am a bit skeptical about the Hughes and Diaz (1994) paper, since it is conceptually similar to the Soon and Baliunas study, and even more importantly, the paper was published before the whole discussion on the preservation of low frequency trends in long tree-ring records really started. An evaluation of detrending techniques applied to tree-ring data and the consequences on retained low frequency variations would likely alter the main conclusions of the Hughes and Diaz paper. So, I think that the paper is in some sense outdated. [Jan Esper]

IPCC (i.e. Briffa) stated that they “in large part accepted” the observation:

Noted – and in large part accepted. Will considered amending text to reflect this.

I made essentially the same point as follows:

6-1282 A 28:21 28:23 Hughes and Diaz [1994] uses proxy series which do not capture centennial trends. It is not usable. [Stephen McIntyre]

While they “in large part accepted” the point as made by Esper, with me that merely said that the point was “taken into account”:

Taken into account – will elaborate

Despite these undertakings, the language in the Second Draft was word-for-word identical to the language in the First Draft, reading as follows:

A later study, based on examination of more quantitative evidence, in which efforts were made to control for accurate dating and specific temperature response, concluded that it was not possible to say anything other than “… in some areas of the Globe, for some part of the year, relatively warm conditions may have prevailed” (Hughes and Diaz, 1994).

Esper didn’t submit comments on the Second Draft. I re-iterated the comment from the First Draft, this time citing Esper’s First Draft comment as additional authority:

6-1139 B 28:56 28:56 Nearly all of the Hughes and Diaz [1994] proxy series have been processed in a way which do not capture centennial trends e.g. the Guiot series and the Serre-Bachet series, the Polar Urals version of Graybill and Shiyatov. In his comment on the FOD, Esper also pointed out that he was “skeptical” about the Hughes-Diaz paper for the same reason. It is irrelevant and should not be used as supposedly refuting Lamb. [Stephen McIntyre (Reviewer’s comment ID #: 309-35)]

This time the comment was rejected out of hand.

Rejected – the citation is a correct one and uses considerably more (and more recent) data than the reviewer refers to. It is not irrelevant.

The issue was whether the Hughes-Diaz chronologies had any centennial variance: they don’t. IPCC’s answer is unresponsive to the criticism – which remains valid.

In the final AR4 report, the language was word for word identical to the First Draft:

A later study, based on examination of more quantitative evidence, in which efforts were made to control for accurate dating and specific temperature response, concluded that it was not possible to say anything other than ‘… in some areas of the Globe, for some part of the year, relatively warm conditions may have prevailed’ (Hughes and Diaz, 1994).

15 Comments

  1. justbeau
    Posted Apr 11, 2010 at 10:28 PM | Permalink

    Peck hammers mortal blows.

    He sounds as subtle as Mickey Spillane. I, the IPCC Jury.

  2. Manfred
    Posted Apr 12, 2010 at 2:18 AM | Permalink

    I can’t see any of these authors in the next IPCC report.

    • Neil Fisher
      Posted Apr 12, 2010 at 5:04 PM | Permalink

      … even if we have to re-define author!

      Sorry, couldn’t resist.

  3. stan
    Posted Apr 12, 2010 at 6:54 AM | Permalink

    After a long successful career as manager of the NY Yankees, Casey Stengel managed the expansion 1962 NY Mets, the worst team in the history of baseball. His famous quote after watching his Mets produce a comedy of errors seems appropriate for this ‘team’ — “Can’t anybody here play this game?!”

  4. John Murphy
    Posted Apr 12, 2010 at 8:27 AM | Permalink

    I know this is OT, but I can’t resist. I just spoke by phone to Osborn at the CRU. During the conversation he told me, apparently seriously, that he knew nothing about any of the Climategate emails. These people can’t tell the truth if telling a lie is even a remote possibility.

  5. Craig Loehle
    Posted Apr 12, 2010 at 8:53 AM | Permalink

    Ah, the 60’s, sitting around the camp fire singing “If I Had a Hammer!” … what? This hammer isn’t about peace and love? Overpeck isn’t hammering out justice?

    Kudo’s to Steve for putting the pieces of the puzzle together.

  6. Bernie
    Posted Apr 12, 2010 at 10:14 AM | Permalink

    Steve:
    Nice follow up on the “hammer” motif. Has Jan Esper commented on this issue or responded to the continued reliance on the 1994 Hughes and Diaz paper? His criticism seems pretty unequivocal.

  7. EdeF
    Posted Apr 12, 2010 at 11:51 AM | Permalink

    There is so much hammering, nailing, hammer blows that I wonder if they filled out one of these:

    http://www.cncbuildingcontrol.gov.uk/cms/assets/CNC_BN_v27_01_10.pdf

  8. Shallow Climate
    Posted Apr 12, 2010 at 1:01 PM | Permalink

    “One of the curious aspects of the IPCC peer review procedure…”: Mr. McIntyre, you’re being way too kind, or is this but another example of your trenchant irony? Now if I, dullard that I am but devoted (I hope) to telling the truth, were composing this, I would have said, “One of the blasphemous aspects of the IPCC review procedure…”. It is absolutely indefensible that IPCC authors have the final say on reviewers’ comments. Any dolt can discern that. I am not Ozymandias, but I have spoken.

  9. LearDog
    Posted Apr 12, 2010 at 1:03 PM | Permalink

    Steve – interesting way that you’ve put the pieces all together. But I don’t think that it had anything to do with IPCC editorial policy. I think that 1) they just don’t like you and 2) were using any means to get back at you.

    Perhaps it was a childish ‘nyaah, nyaah, nyaah’ kind of thing, or perhaps more of a concern about the optics of agreeing with you and thereafter having to defend to “The Team’?

    • Steve McIntyre
      Posted Apr 12, 2010 at 1:46 PM | Permalink

      Re: LearDog (Apr 12 13:03),
      But in this case, Esper and I were on the same side. In the First Draft responses, the authors ignored both of us equally. And the point here is not just that they ignored us – it’s that they led the Review Editor to think that they had taken the comments on board and then did what they wanted to do anyway.

      • Dr Iain McQueen
        Posted Apr 12, 2010 at 3:31 PM | Permalink

        Re: Steve McIntyre (Apr 12 13:46), How could you you possibly be on the same side? Don’t be ridiculous! We have to be rude, offhand and hostile to McIntyre, and that has absolute precedence over all else. It is IPCC policy.

  10. Mike Davis
    Posted Apr 12, 2010 at 3:10 PM | Permalink

    But the Hughes and Diaz statement is as valid for current climate as it was for the MWP.

  11. Posted Apr 12, 2010 at 6:04 PM | Permalink

    It seems really odd that the response was: “the citation is a correct one and uses considerably more (and more recent) data than the reviewer refers to.”

    Neither McIntyre nor Esper questioned the amount or newness of the data. They both noted that the way in which the data had been analyzed made the results less probative, if not invalid.

    Did the IPCC authors really not understand the difference between data and analysis?

  12. Geoff Sherrington
    Posted Apr 12, 2010 at 8:28 PM | Permalink

    It seems inarguable that the release of new data since AR4 and the ongoing look at the CRU emails will make some earlier papers invalid. For example, if a future reconstruction shows that global temperature has changed at a far different rate in the instrumented period than is currently assumed, the calibration of many temperature proxies will need to be re-written.

    On Steve’s theme above, “it should have been changed but it was not”, I have not noticed (m)any retractions of, or corrections to, a host of papers which are now under a cloud through either CRU emails or recent measurements like sea level change. Honest science would have picked this up and the revised publications should now be appearing. Have you seen any?

    It is not a solution to delete and forget (as in the Yamal divergence). Science should not entertain the progression of myths by inaction.

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