www.uoguelph.ca/~rmckitri/research/fallupdate04/update.fall04.html
first part concerned the provenance of the data used for our analysis and was released in November 2003. We can now update this process, starting with the latter item first.
short article to Nature, arguing that the shape of the MBH98 hockey-stick depended on: transforming each tree ring proxy prior to calculating principal components (PCs) by subtracting its 1902-1980 mean rather than subtracting the mean of the length of the PC itself (e,g, 1400-1980 for AD1400 calculation step), as would be done in usual software and the duplicate use of the same Gasp tree ring series in two locations in the MBH98 data base, and, in one of its duplicate uses, an extrapolation at the beginning to make the series available in AD1400 step calculations, while incorrectly listing the first available date as AD1400, thereby concealing the extrapolation. Although MBH98 claimed great "robustness" for its reconstructions, even claiming robustness to the exclusion of all tree ring data, we showed that its results were not robust to seemingly slight changes in these aspects of the methodology. We also showed that, once these issues were remedied, our results held up even when we included the NOAMER PCs back to AD1400, which had been a specific methodological difference earlier. Our cover letter outlined the purpose of our submission, recognizing that it did not fit neatly into Nature's submission categories, which classify submissions as "Letters", "Articles" and "Communications Arising". "Letters" and "Articles" are reports on "original" work and have longer word limits than "Communications Arising", which may be criticisms. We thought that the submission could be construed as a "letter", although of an unusual type. Our submission was a comment on a publication, but represented a great deal of original work, which obviously no one else had done. Although the content was critical in nature, the topic was of extreme international importance and we stated explicitly that we were open to guidance on editorial format and asked that the submission be valued on its merits.
favorable revise and resubmit, at which time we were asked to add additional material in order to respond to referee comments (our paper then standing at 1910 words).
Referee #2 stated: The technical criticisms raised by McIntyre and McKritrik (MM) concerning the temperature reconstructions by Mann et al (MBH98), and the reply to this criticism by Mann et al is quite difficult to evaluate in a short period of time, since they are aimed at particular technical points of the statistical methods used by Mann et al, or at the use of particular time series of proxy data. A proper evaluation would require to redo most of the calculations presented in both manuscripts, something which is obviously out of reach in two weeks time. Furthermore, both manuscripts seem to contradict each other in some basic facts. Therefore, my comments are based on my impression of the consistency of the results presented, but there is a wide margin of uncertainty that could be resolved only by by looking in detail into the whole data set and the whole software used by the authors. In general terms I found the criticisms raised by McIntyre and McKritik worth of being taken seriously. They have made an in depth analysis of the MBH reconstructions and they have found several technical errors that are only partially addressed in the reply by Mann et al. We had pointed to the overwhelming weighting given to one hockey stick-shaped North American tree ring series (Sheep Mountain CA) as a result of the subtraction of the 1902-1980 mean. which we found interesting was that their PC1 did not just depend on Sheep Mountain, but 14 other sites had at least 25% of the contribution of Sheep Mountain.
re-submitted in late March, adding a new paragraph showing that these 14 highly weighted sites in the PC1 were all from a group of specialized and controversial high-altitude bristlecone pine series, studied by Graybill and Idso (1993), exhibiting an anomalous 20th century growth spurt, which yields hockey-stick shaped growth series. Graybill and Idso stated that explicitly that the 20th century growth could not be explained by local or regional temperature; co-author Hughes in Hughes and Funkhouser (2003) said that the anomalous growth was a "mystery".
NOAMER/BACKTO_1400-CENSORED subdirectory at Professor Mann's FTP site. The PC1 in this subdirectory proved to be virtually identical to the one we calculated using standard PC methods on the entire North American network. Carrying these PCs forward into an NH temperature index led to a reconstruction almost the same as ours! Nature then asked us to reduce the paper down to 800 words.
final version was within the 800-word limit and was submitted on April 9 We did not hear the results of the re-submission for four months. When we inquired about delays, Nature said that they had not heard back from reviewers. It turns out that Nature had added a third reviewer, which may have contributed to the delays.
The main reason was that the issues raised are too technical to resolve in the now 500 word space available: In the light of this detailed advice, we have regretfully decided that publication of this debate in our Brief Communications Arising section is not justified. This is principally because the discussion cannot be condensed into our 500-word/1 figure format (as you probably realise, supplementary information is only for review purposes because Brief Communications Arising are published online) and relies on technicalities that do not bring a clear resolution of the underlying issues. This decision primarily reflected the views of the new reviewer, who stated: Generally, I believe that the technical issues addressed in the comment and the reply are quite difficult to understand and not necessarily of interest to the wide readership of the Brief Communications section of Nature. I do not see a way to make this communication much clearer, particularly with the space requirements, as this comment is largely related to technical details. This reviewer did not object to any of our findings per se. Readers may share our surprise that the matters raised are "too technical" for consideration in a science journal; additionally, whether or not the matters were of interest to a "wide readership" (and we believe that they are), potential defects in MBH98 affect Nature's publication record and require disclosure. Our old referees again commented on the difficulty of resolving who was right and who was wrong. Referee #2 (Referee #1 of the first round) remained sympathetic, and stated: The amount of material, often contradictory, is simply too complex and lengthy to resolve all the rights and wrongs in a realistic length of time" Only a reader with several days to spare (longer if they are unfamiliar with the area), to chase references and probably the authors, could hope to come close to a full understanding of the arguments. I started my original review by saying that I found merit in the arguments of both MBH & MM To rewrite this, I believe that some of the criticisms raised by each group of the other's work are valid, but not all. I am particularly unimpressed by the MBH style of 'shouting louder and longer so they must be right'. However, Referee #3 (Referee #2 of the first round) was impressed by some of the new arguments of Mann et al. In his new comments, he expressed concern about whether the points could be made within the space limitations and stated: I see some merit in MM04 and I would encourage them to pursue their testing of MBH98, and by the way other reconstructions. As I wrote in my first evaluation, this should be a normal and sound scientific process that should not hampered. For instance, questions that seem to be quite critical, such as the sensitivity of the MBH98 reconstructions in more remote periods to changes or omissions in the proxy network or the dependency of the final results to the rescaling of the reconstructed PCs, have become clearer to me now. At the moment, my opinion is that the present MM04 manuscript could be of interest just for the bunch of specialist working exa...
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