July 20, 2004

Dear Dr. Cotter,

Thank you for your reply to my email. I appreciate your consideration and would like to clarify a couple of lingering matters.

You mentioned that a misunderstanding had arisen because you had not received our request asking Nature to approach Mann et al. to remove a claim pertaining to our submitted Communications Arising from their website and were not aware of this request. We submitted this request to Karl Ziemelis on June 14, 2004 (see attached email) and he responded June 24 (also attached) making reference to the forthcoming Corrigendum.

Additionally, when we were first informed of a forthcoming Corrigendum by Heike Langenberg in March, we sent the following comment in reply:

"We are concerned that Professor Mann may use the occasion of a printed response to engage in controversy with our previous criticism of MBH98, as he has done in his response to you. Obviously, such controversy is distinguishable from corrections of inaccuracies in MBH98. We would like an opportunity to reply to any such controversy."

Dr Langenberg responded (March 14):

"Please be assured that the Correction will contain no mention of the controversy between yourselves and Mann et al; it will be a plain correction stating the errors in the original Supplementary Information, and their correction".

We were shown the uncorrected page proofs of the Corrigendum prior to its publication, and it corresponded to Dr Langenberg's description. In particular, it did not contain the claim that the errors do not affect previous results. This claim goes beyond the "plain correction" as promised by Dr Langenberg; indeed it is at the very heart of the controversy. It appears to have been inserted at the proof-correction stage after the review process had finished and, in any case, after we had had an opportunity to comment.

In our Communication Arising, we had already presented evidence that shows the Corrigendum sentence to be wrong and peer reviewers of our submission did not accept Professor Mann's response. Indeed, their rejection of Professor Mann's response was an important factor in their recommendation of our submission for publication.

I am sure that you can understand our current bewilderment regarding the publication of the highly controversial last sentence of the Corrigendum, in light of the previous peer review comments and Dr. Langenberg's undertaking, especially when this sentence is now being circulated by Professor Bradley and others as Nature's position on the issues involved.

We appreciate your suggestion that we could highlight this disagreement in a revision of the Communications Arising. However, we don't know when or even if our Communications Arising will be published and are obliged to respond to the situation as it currently stands. From its previous review of our Communications Arising, Nature is (and has been) in a position to know that Professor Mann's defence of the position represented by the controversial final sentence of the Corrigendum was not accepted elsewhere by Nature's referees. Accordingly, we request that the final sentence of the Corrigendum be retracted together with the offending section of the SI referred to in our previous email.

The introduction of new material on the tree ring data was in response to comments by referees and Professor Mann and was important in ensuring that the analysis was complete. Had we known that it would require recruitment of a new referee, we would have suggested candidates whose work we have studied and who are not collaborators with us or with Mann, Bradley and Hughes. If a name is still needed please advise.

Again, we appreciate your consideration in these matters and regret that we are troubling you with these matters.

Yours truly,

Stephen McIntyre and Ross McKitrick

[INCLUSION: June 24, email]