From	Michael E. Mann	Date	Fri, 31 Oct 2003 05:37:03 -0500
To	Tim Osborn, Phil Jones, ray bradley, Tim Osborn, Keith Briffa, Tim Osborn
CC	Malcolm K. Hughes
Subject	RE: CLIMLIST
Thanks very much Tim, I was hoping that the revisions would ally concerns people had. I'll look forward to your comments on this latest draft. I agree w/ Malcolm on the need to be careful w/ the wording in the first paragraph. The first paragraph is a bit of relic of a much earlier draft, and maybe we need to rethink it a bit. Takinig the high road is probably very important here. If *others* want to say that their actions represent scientific fraud, intellectual dishonesty, etc. (as I think we all suspect they do), lets let *them* make these charges for us! Lets let our supporters in higher places use our scientific response to push the broader case against MM. So I look forward to peoples attempts to revise the first par. particular. I took the liberty of forwarding the previous draft to a handfull of our closet colleagues, just so they would have a sense of approximately what we'll be releasing later today--i.e., a heads up as to how MM achieved their result... look forward to us finalizing something a bit later--I still think we need to get this out ASAP... mike SAt 03:01 AM 10/31/2003 +0000, f055 wrote: Dear all, I've just finished preparing a detailed response offline, only to log on to send it to you all and find new versions from Mike plus more comments and information. Well, I don't have time to change my message now, so will paste it below this message. But bear in mind that the new draft may well have allayed many of my concerns - in particular, a quick glance shows the figure to be much more convincing than the one Mike circulated earlier, indeed it seems to be utterly convincing! I'll reply again on Friday morning once I've had time to read the new draft. In the meantime, here is my message as promised. ************************************************************ Dear MBH (cc to CRU), The number of emails has been rather overwhelming on this issue and I'm struggling to catch up with them! But I will attempt to catch up with a few things here... (1) The single worst thing about the whole M&M saga is not that they did their study, not that they did things wrong (deliberately or by accident), but that neither they nor the journal took the necessary step of investigating whether the difference between their results and yours could be explained simply by some error or set of errors in their use of the data or in their implementation of your method. If it turns out, as looks likely from Mike's investigation of this, that their results are erroneous, then they and the journal will have wasted countless person-hours of time and caused much damage in the climate policy arena. (2) Given that this is the single worst thing about the saga, we must not go and do exactly the same in rushing out a response to their paper. If some claims in the response turned out to be wrong, based on assumptions about what M&M did or assumptions about how M&M's assumptions affect the results, then it would end up with a number of iterations of claim and counter claim. Ultimately the issue might be settled, but by then the waters could be so muddied that it didn't matter. (3) Not only do I advise against an overly rushed response, but I'm also wondering whether it really ought to be only from MBH, for three reasons. (i) It is your paper/results that are being attacked. (ii) It is difficult to endorse everything that Mike has put in the draft response because I don't know 100% of the details of MBH and the MBH data. Sure, I can endorse some things, but others I wouldn't know. Sure, I accept Mike's explanation because he's looked at this stuff for 4 days and I believe he'll have got it right - but that's different to an independent check. That must come from Ray or Malcolm if possible. (iii) If it does come to any independent assessment of who's right and who's wrong, then it would be difficult for us to be involved if we had already signed up to what some might claim to be a knee-jerk reaction to the M&M paper. If that happened, then you would want us to be free to get involved to make sure the process was fair and informed. This sounds like a cop out, but - like I say - I'm not sure about point (3) so feel free to try to convince me otherwise if you wish. Anyway Keith or Phil may be happy to sign up to a (quick or slow) response, despite my reservations above. I really advise a very careful reading of M&M and their supplementary website to ensure that everything in the response is clearly correct - precisely to avoid point (2). I've only just started to do this, but already have some questions about the response that Mike has drafted. (a) Mike, you say that many of the trees were eliminated in the data they used. Have you concluded this because they entered "NA" for "Not available" in their appendix table? If so, then are you sure that "NA" means they did not use any data, rather than simply that they didn't replace your data with an alternative (and hence in fact continued to use what Scott had supplied to them)? Or perhaps "NA" means they couldn't find the PC time series published (of course!), but in fact could find the raw tree-ring chronologies and did their own PCA of those? How would they know which raw chronologies to use? Or did you come to your conclusion by downloading their "corrected and updated" data matrix and comparing it with yours - I've not had time to do that, but even if I had and I found some differences, I wouldn't know which was right seeing as I've not done any PCA of western US trees myself? My guess would be that they downloaded raw tree-ring chronologies (possibly the same ones you used) but then applied PCA only to the period when they all had full data - hence the lack of PCs in the early period (which you got round by doing PCA on the subset that had earlier data). But this is only a guess, and this is the type of thing that should be checked with them - surely they would respond if asked? - to avoid my point (2) above. And if my guess were right, then your wording of "eliminated this entire data set" would come in for criticism, even though in practise it might as well have been. (b) The mention of ftp sites and excel files is contradicted by their email record on their website, which shows no mention of excel files (they say an ASCII file was sent) and also no record that they knew the ftp address. This doesn't matter really, since the reason for them using a corrupted data file is not relevant - the relevant thing is that it was corrupt and had you been involved in reviewing the paper then it could have been found prior to publication. But they will use the email record if the ftp sites and excel files are mentioned. (c) Not sure if you talk about peer-review in the latest version, but note that they acknowledge input from reviewers and Fred Singer's email says he refereed it - so any statement implying it wasn't reviewed will be met with an easy response from them. (d) Your quick-look reconstruction excluding many of the tree-ring data, and the verification RE you obtain, is interesting - but again, don't rush into using these in any response. The time series of PC1 you sent is certainly different from your standard one - but on the other hand I'd hardly say you "get a similar result" to them, the time series look very different (see their fig 6d). So the dismal RE applies only to your calculation, not to their reconstruction. It may turn out that their verification RE is also very negative, but again we cannot assume this in case we're wrong and they easily counter the criticism. (e) Claims of their motives for selective censoring or changing of data, or for the study as a whole, may well be true but are hard to prove. They would claim that their's is an honest attempt at reproducing a key scientific result. If they made errors in what they did, then maybe they're just completely out of their depth on this, rather than making deliberate errors for the purposes of achieving preferred results. (f) The recent tree-ring decline they refer to seems related to tree-ring-width not density. Regardless of width of density, this issue cannot simply be dismissed as a solved problem. Since they don't make much of an issue out of it, best just to ignore it. (g) [I'm rambling now into an un-ordered list of things, so I'll stop soon!] The various other problems relating to temperature data sets, detrended standard deviations, PCs of tree-ring subsets etc. sound likely errors - though I've got no way of providing the independent check that you asked for. But it is again a bit of a leap of faith to say that these *explain* the different results that they get. Certainly they throw doubt on the validity of their results, but without actually doing the same as them it's not possible to say if they would have replicated your results if they hadn't made these errors. After all, could the infilling of missing values have made much difference to the results obtained, something that they made a good deal of fuss about? (h) To say they "used neither the data nor the procedures of MBH98" will also be an easy target for them, since they did use the data that was sent to them and seemed to have used approximately the method too (with some errors that you've identified). This reproduced your results to some extent (certainly not perfectly, but see Fig 6b and 6c). Then they went further to redo it with the "corrected and updated" data - but only after first doing approximately what they claimed they did (i.e. the audit). These comments relate to random versions of the draft response, so apologies if they don't all seem relevant to the current draft. I don't have these in front of me, here at home, so I'm doing this from memory of what I've read over the past few days. But nevertheless, the point is that a quick response would ultimately require making a number of assumptions about what they did and assumptions about whether this explains the differences or not - assumptions that might be later shot down (in part only, at most, but still sufficient to muddy the debate for most outsiders). A quick response ought to be limited to something like: --------------------------------------------- The recent paper by McIntyre and McKitrick (2003; hereafter MM03) claims to be an "audit" of the analysis of Mann, Bradley and Hughes (1998; hereafter MBH98). MM03 are unable to reproduce the Northern Hemisphere temperature reconstruction of MBH98 when attempting to use the same proxy data and methods as MBH98, though they obtain something similar with clearly anomalous recent warming (their Figure 6c). They then make many modifications to the proxy data set and repeat their analysis, and obtain a rather different result to MBH98. Unfortunately neither M&M nor the journal in which it was published took the necessary step of investigating whether the difference between their results and MBH98 could be explained simply by some error or set of errors in their use of the data or in their implementation of the MBH98 method. This should have been an essential step to take in a case such as this where the difference in results is so large and important. Simple errors must first be ruled out prior to publication. Even if the authors had not undertaken this by presenting their results to the authors of MBH98, the journal should certainly have included them as referees of the manuscript. A preliminary investigation into the proxy data and implementation of the method has already identified a number of likely errors, which may turn out to be the cause of the different results. Rather than repeating M&M's failure to follow good scientific practise, we are witholding further comments until we can - by collaboration with M&M if possible - be certain of exactly what changes to data and method were made by M&M, whether these changes can really explain the differences in the results, and eventually which (if any) of these changes can be justified as equally valid (given the various uncertainties that exist) and which are simply errors that invalidate their results. ----------------------------------------- Hope you find this all helpful, and despite my seemingly critical approach, take them in the spirit with which they are aimed - which is to obtain a strong and hard hitting rebuttal of bad science, but a rebuttal that cannot be buried by any minor innaccuracies or difficult-to-prove claims. Best regards Tim ______________________________________________________________ Professor Michael E. Mann Department of Environmental Sciences, Clark Hall University of Virginia Charlottesville, VA 22903 _______________________________________________________________________ e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137 [1]http://www.evsc.virginia.edu/faculty/people/mann.shtml References 1. http://www.evsc.virginia.edu/faculty/people/mann.shtml