Dear Ms. Cotter,

 

In January 2004, we submitted a Communications Arising on a paper by Mann, Bradley and Hughes (MBH98). You sent this to Professor Mann for a response, and there was a subsequent round of submissions thereafter. It is our understanding that our submission was confidential and that Professor Mann could not use it for any purposes other than to respond to the submission, under the Nature policy stated below:

 

The responders (defined as the authors of the published contribution that is the subject of the comment, and no-one else) must keep the comment confidential and must not use it for their own research or for any other purpose apart from replying to the comment, nor can they distribute it without first obtaining Nature's permission.

Our analysis received favourable reviews, and we were asked to respond to reviewer comments as well as those of Professor Mann. We were then asked to reduce the length to 800 words which we did, and re-submitted on April 9, 2004.

 

Because of Nature’s embargo policy, we have been unable to respond to many questions concerning our analysis of Mann et al. (1998), which are covered in our Communications Arising. We have notified you of this and have sought an update from you on several occasions as to the status of our submission.

 

On July 1, 2004, Nature published a Corrigendum to MBH98 by Professor Mann dealing with numerous data errors in his original article. We are writing to protest a breach of the embargo on the Communications Arising contained in the Corrigendum and its Supplementary Information.

 

In our Communications Arising, we showed that a data transformation prior to calculation of principal components has a material impact on the results of MBH98. In the Supplementary Information to the Corrigendum, posted on Nature’s website, Mann et al. state:

 

All predictors (proxy and long instrumental and historical/instrumental records) and predictand (20th century instrumental record) were standardized, prior to the analysis, through removal of the calibration period (1902-1980) mean and normalization by the calibration period standard deviation. Standard deviations were calculated from the linearly detrended gridpoint series, to avoid leverage by non-stationary 20th century trends. The results are not sensitive to this step (Mann et al, in review).

(emphasis added). The last sentence is a direct reference to the very issue highlighted in our Communications Arising, and cites Professor Mann’s submission to Nature in response to our Communications Arising. Professor Mann’s arguments on this matter were not accepted by the peer reviewers of our original submission. His insertion of this statement thus attempts to pre-empt our Communications Arising, and does so in a manner that breaches Nature’s confidentiality policies. We therefore ask that this claim be removed from the Nature website.

 

We are especially concerned because several weeks ago we provided notice to Nature that the above claim had been posted up on Professor Mann’s own FTP site and requested that Nature take steps to have this statement removed until the Communications Arising was published. Nature has not only ignored this request, but has astonishingly placed the claim on its own website.

 

We are also extremely concerned about the last sentence in the published Corrigendum, stating that the various errors, omissions and misrepresentations in MBH98 do not “affect” their results. In March 2004, we were shown page proofs of the Corrigendum, which did not contain this sentence. It appears that it was inserted after the review process had closed. Like the above sentence on the Nature web site, we have shown in our Communications Arising that it is untrue. By publishing it while the Communications Arising is under embargo, Professor Mann has attempted to pre-empt our submission and has breached the embargo under which we continue to withhold our own material. This sentence is not merely incidental; it is already being cited and circulated by Professor Bradley and perhaps others.

 

While we understand that the editors responsible for the Corrigendum may not have co-ordinated with you, the overall result is very unsatisfactory. We are within our rights to formally ask for a retraction of this sentence and may do so. But the best way to resolve this matter would be to deal promptly with our Communications Arising, which has been pending for almost 3 months, and let readers weigh both sides of the discussion and decide for themselves.

 

Yours truly,

 

Stephen McIntyre

Ross McKitrick