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Fudge Swirl

May 15, 2010

There’s a kinda interesting/kinda repetitive discussion going on over at Roger’s blog about whether Mike’s “nature trick” to “hide the decline” attempt was either a face-saving fudge or a fraud. It’s a response to this Der Spiegel article, which appears to suggest that the climate science was compromised. Lots to say about this article, but let’s just look at the fudge/fraud issue.

Roger’s on the fudge side. Some of his readers are on the fraud side. I guess I’m on a side similar to Roger’s–that is, I see it as a fudge–but I disagree that it’s a “face-saving” fudge. A face-saving fudge would involve some attempt to save face, or some attempt to look good given other statements or claims that may have been made previously. I can’t imagine that that was what was going on when the climate scientists sought to hide the decline.

More likely to me, and more defensible in many ways, is that Mann and others were fudging the findings in order to “smooth them out” so that they were easier to read, so that their findings would not be misinterpreted by a lazy and apathetic press, so that an anomalous line wouldn’t distract from the overarching observation, which is that there is persistent change. Moreover, I assume that they could provide a moderately plausible argument for this, since the instrumental record was also in place and widely viewed to be more reliable. It’s not like, after all, we turn to ice core studies, or dendro studies, for most of our 20th century climate information.

What makes this hide the decline move problematic is that it flies in the face of what can sometimes be the insistence from the climate community that they are not being political. If my read is correct–and frankly, I think it is the most charitable read–smoothing out findings and hiding the decline is, without question, a move that is taken with political considerations in mind. Seems to me that climate scientists would do better just to acknowledge that this is a deeply political issue and to do so publicly. It won’t undermine the science.

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6 comments

  1. I’m afraid it very much would undermine the science. Plus it would make RP Jr. orgasmically happy, right? BTW, here he is in Sunday’s Boston Globe being typically “helpful” (quote at top of page two).

    Re “hide the decline,” the most recent post at Deep Climate exposes a key element of the disinformation campaign that Roger’s been so happy to cooperate with. The simple fact is that there was nothing that could be described as a fudge. Several of the tree-ring series went askew post-1960 because other environmental factors began to affect them.

    Via DC, this is the “smoking gun” comment from the TAR drafting process (Tim Osborn writing to Mike Mann and another author):

    Keith [Briffa] has asked me to send you a timeseries for the IPCC multi-proxy reconstruction figure, to replace the one you currently have. The data are attached to this e-mail. They go from 1402 to 1995, although we usually stop the series in 1960 because of the recent non-temperature signal that is superimposed on the tree-ring data that we use.

    So now it’s a fudge to include data that’s known to be contaminated?


    • Steve:

      Why doesn’t the fact that “several of the tree-ring series went askew post-1960 because other environmental factors began to affect them” render tree-ring data as invalid as a proxy for temperature over their entire period?

      At least until we know what is causing the divergence.

      How do we know these other factors were not present during other periods in the tree ring data period?

      What were these other factors? CO2? Drought? Acid rain? To much rain? Volcanic activity?

      I certainly don’t think we can conclude the data is contaminated.

      The tree-ring data is what it is.

      Science needs to determine what is causing the divergence, and whether that cause could have influenced the tree-ring data at other periods over the last 2000 years.

      If there is one or more non-temperature signals imposed onto the tree-ring data, in addition to temperature, we have to tease those out and determine what they are – not ignore the data because it is “contaminated”.


      • That was quite lawyerly of you, Rick. You have no idea what the facts of the matter are, but have the gall to construct an argument anyway. I’d tell you to go read the scientific literature, but that’s not going to happen.


  2. […] like Howard Beale, thinks the press is easily manipulated. An environmental ethics philosopher is sympathetic to “Hide the Decline” climate scientists because…well, you read (emphasis added): […]


  3. “More likely to me… is that Mann and others were fudging the findings in order to ‘smooth them out’ so that they were easier to read, so that their findings would not be misinterpreted by a lazy and apathetic press, so that an anomalous line wouldn’t distract from the overarching observation, which is that there is persistent change.”

    People seem to conflate different events under rubrics like “hide the decline.” What, specifically, are you referring to here?

    It seems likeliest that you mean the way the “Divergence Problem” was described in the IPCC Third Assessment and 4th Assessment reports. This is the phenomenon first noted by Briffa et al (Nature, 1998), where the correlation between tree-rings and temperature worsened after about 1960 in many places.

    If that is what you mean, then Rick4 raises some good points. ‘Carrot Eater’ and I discussed related issues from about Comment #43308, most of the way down a lengthy “Blackboard” thread.

    The Divergence Problem is easy to grasp, on the surface: in the 1960s, many tree ring series showed less sensitivity to temperature.

    How this observation can be incorporated into paleoclimate reconstructions seems far from easy and far from obvious. AR4 WG1 Ch. 6.6 says, ““In their large-scale reconstructions based on tree ring density data, Briffa et al. (2001) specifically excluded the post-1960 data in their calibration against instrumental records, to avoid biasing the estimation of the earlier reconstructions.”

    What’s the basis for claiming that excluding post-1960 data avoids the biasing of estimates? When the step is taken, how does that change the calculation of 95% confidence intervals for the reconstructed temperature series?


  4. […] like Howard Beale, thinks the press is easily manipulated. An environmental ethics philosopher is sympathetic to “Hide the Decline” climate scientists because…well, you read (emphasis […]



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