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Myles Allen has written here blaming Bishop Hill for “keeping the public focussed on irrelevancies” like the Hockey Stick:

My fear is that by keeping the public focussed on irrelevancies, you are excluding them from the discussion of what we should do about climate change

But it’s not Bishop Hill that Myles Allen should be criticizing; it’s John Houghton who more or less made the Hockey Stick the logo of the IPCC. Mann was told that IPCC higher-ups wanted a visual that didn’t “dilute the message” and they got one: they deleted the last part of the Briffa reconstruction – Hide the Decline. If, as Allen now says, it’s an “irrelevancy”, then Houghton and IPCC should not have used it so prominently. And they should not have encouraged or condoned sharp practice like Hide the Decline.

In the run-up to AR4, I suggested that, if the topic was “irrelevant”, as some climate scientists have said, then IPCC should exclude it from the then AR4. Far from trying to keep the topic alive in AR4, I suggested that it be deleted altogether. I guess that there was a “consensus” otherwise. If Allen wants to complain, then he should first criticize IPCC.

Bishop Hill links to a presentation by Myles Allen to a 2011 conference on Climategate, which like every other such handwringing introspection by climate “communicators”, notably failed to invite any of the major CRU critics – people who might actually have given them some insight into Climategate. In his presentation to climate communicators, Allen gave his own version of Hide the Decline. Allen showed the graphic below, sneering that the entire effect of Climategate was 0.02 deg C in the 1870s.

Needless to say, Allen’s graph has nothing to do with Hide the Decline and the Climategate dossier. Allen’s graph shows the CRUTEM temperature index from 1850, not the 1000 year reconstructions in which Hide the Decline occurred. CRUTEM was only mentioned a couple of times in the Climategate dossier. Climategate was about the Hockey Stick, though this point was misunderstood by Sarah Palin and now, it seems, Myles Allen.


Figure 1. Allen in front of temperature history.

In contrast, here’s a graphic from Richard Muller’s 2011 lecture. Unlike Allen, Muller understood Hide the Decline, which is shown here in one of its manifestations. (This is the WMO graphic; the more important Hide the Decline was in the IPCC Third and Fourth Assessment reports.) Hide the Decline is not 0.02 deg C in the 1870s; it was Briffa, Mann and Jones deleting the inconvenient portion of the Briffa reconstruction after 1960. And it wasn’t a microscopic difference. This difference is large enough that it might well have “diluted the message” that Houghton and others wanted to convey.

Figure 2. Muller in front of WMO hockey stick – a 1000 year reconstruction. Left – Hide the Decline; right – actual data.

While one would hope and expect that Myles Allen would have had a better factual grasp on Climategate issues than Sarah Palin, it seems that we’ve been disappointed.

Allen’s decision to show temperature data rather than Hockey Stick reconstructions cleverly draws attention away from the problems of those reconstructions. The Climategate emails have a apt phrase for Allen’s technique. Showing an unrelated dispute about a temperature graphic rather than the decreasing Briffa reconstruction is itself just another …. trick to hide the decline. :)