Climate Audit

We took another try at Nature corrspondence. In their news report on the Mann graph discussed here , they stated:

In its report, released on 22 June, the NAS committee more-or-less endorses the work behind the graph.

They published a whining letter about the NAS panel and news conference by Mann et al, where they claimed that it was "hard to imagine" how they could have disclosed uncertainties more fulsomely. Of course, it was very "easy to imagine" and we sent in a letter to Nature, which they refused to print.

Now obviously whatever else the NAS Panel did, they did not "more or less endorse the work behind the graph". So we sent the following letter tracking the form of language of the Mann et al letter to some extent:

Your News story “Academy affirms hockey-stick graph”‘? (Nature 441, 1032; 2006) states that the US National Academy of Sciences (NAS) panel “more-or-less endorses the work behind the [Mann et al hockey stick] graph”‘?. This conclusion was not stated in the NAS report itself nor by any of the panellists at the NAS panel press conference releasing the report.

Many specific findings of the NAS panel show that they did not endorse the work behind the hockey stick. The NAS report stated that the Mann et al decentered principal components methodology should not be used; that temperature reconstructions should avoid the use of strip-bark bristlecones and foxtail proxies; that the Mann et al reconstruction was strongly dependent on these problematic proxies; that their reconstruction failed important verification tests; and that they had incorrectly estimated uncertainties in their reconstruction.

At the press conference, panel chairman North said that he agreed with the “substance”‘? of the Mann et al reconstruction. However, this language is nowhere used in the report itself, where the panel expressly referred to the reconstruction merely as “plausible”‘? and specifically withheld any attribution of confidence intervals for the period before 1600.

Nature, who seem to have abandoned any attempt at an even-handed treatment of the issues, even where they have themselves inaccurately reported on a matter, replied:

Thank you for your Correspondence submission, which we regret we are unable to publish. Our news story was indeed citing North’s comments at the press conference, which as they say "substantially" support Mann et al., and which is clear from the text of the news story.Thank you again for writing to us.

For comparison, once again, here is the letter from Mann et al which was published:

Your News story “Academy affirms hockey-stick graph”‘? (Nature 441, 1032; 2006) states that the US National Academy of Sciences (NAS) panel “concluded that systematic uncertainties in climate records from before 1600 were not communicated as clearly as they could have been”‘?. This conclusion is not stated in the NAS report itself, but formed part of the remarks made by Gerald North, the NAS committee chair, at the press conference announcing the report.

The name of our paper is “Northern Hemisphere temperatures during the past millennium: inferences, uncertainties, and limitations”‘? (Geophys. Res. Lett. 26, 759″€œ762; 1999). In the abstract, we state: “We focus not just on the reconstructions, but on the uncertainties therein, and important caveats”‘? and note that “expanded uncertainties prevent decisive conclusions for the period prior to AD 1400″‘?. We conclude by stating: “more widespread high-resolution data are needed before more confident conclusions can be reached.”‘? It is hard to imagine how much more explicit we could have been about the uncertainties in the reconstruction; indeed, that was the point of the article!

The subsequent confusion about uncertainties was the result of poor communication by others, who used our temperature reconstruction without the reservations that we had stated clearly.