Mann oh Mann. Tom Nelson continues to wade through the 5000+ Climategate 2 emails. I’ve selected a few he’s highlighted in the vein of behind the scenes discussion of Dr. Michael Mann’s infamous “hockey stick” which claimed we were living in a period of unprecedented warmth.
It seems though, that the stick isn’t nearly as robust as we have been led to believe, such as it isn’t consistently replicable by the team itself and Briffa admits the trees are more precipitation sensitive (told ya so), and besides, Mann says it all big oil’s fault anyway.
The triggering issue was the “divergence” problem as raised by Rosanne D’Arrigo, that a spatially and temporally complex difference has arisen between many of the long tree-ring records and the instrumental record more recently than the calibration period in many cases. This has been in the literature for a while, as you know much better than I do, and was not highlighted by Rosanne in her talk, but some committee members jumped on it in questions, and she was not convincing that trees were thermometers when it was warm a millennium ago but are not thermometers when it is warm now.
…(I’m happy to go into details as to why the arguments were not convincing, insofar as I captured the arguments, but they were not convincing to me, and looking around the committee room, I don’t think they were convincing to important members of the committee.) …I don’t want to stir up trouble, I don’t want to piss off the tree-ring people yet again, but I do think that the tree-ring workers (and by association, all of us who do climate change) have a serious problem, and have not answered it very well yet. If better answers are out there, I hope that they come out soon.
date: Wed Feb 15 15:49:58 2006 from: Keith Briffa subject: Re: Science paper to: Henry Pollack
thanks Henry – sorry also about the ridiculous way the Paleo chapter is being rushed. I have found loads of errors /typos that crept in
Email 4853, Keith Briffa, Nov 2006: “dropped the inference of direct, positive association with temperature, because we added in sites that Mike in particular had used because of their inverse sensitivity – ie they were really more precipitation sensitive”
cc: email@example.com date: Mon, 06 Nov 2006 12:26:25 +0000 from: Keith Briffa subject: TSU Figure label to: Jonathan Overpeck , Eystein Jansen
..Tim has just pointed out to me that the caption to the current TS-20 contains the words “locations of temperature sensitive proxy records..”. In the revision of the Figure ( showing the 3 maps ) as presented in the Chapter , we refer to sites ” used to reconstruct temperature” and dropped the inference of direct, positive association with temperature, because we added in sites that Mike in particular had used because of their inverse sensitivity – ie they were really more precipitation sensitive . It would be better to amend the TSU caption to show the latter wording to account for this also. cheers Keith
Email 4854, Oct 2003, Phil Jones: “It is rather odd that the email said [M&M] had rerun his (Mann’s) exact analysis and got quite different results. I know I couldn’t do this, as when Keith, Tim and me wanted to do some comparisons with MBH98 a few years ago a few of the series could not be made available.”
subject: Re: CONFIDENTIAL
Thanks Phil, Got your email just as I sent off my latest. I agree fully with what you say–it is very difficult to repeat such an analysis exactly, and the real point here is, who knows what this guy (Steven McIntyre–I don’t know who the supposed 2nd author is) actually did. The Mann et al ’99 paper was clear that the results were sensitive to a small number of skillful predictors prior to AD 1400, and that non-climate biases had to be corrected for in some of the longer series to get a skillfully cross-validated reconstruction. Without knowing what the guy did, I’m guessing that he doesn’t even demonstrate that his alternative “reconstruction” passes cross-validation. If not, its all moot… But more fundamentally, this wasn’t submitted to a legitimate peer-reviewed scientific journal. Its a social science journal, and one that has shown a disdain for peer review (e.g. in publishing the Soon et al Climate Research paper essentially in its original unedited form–and see the recent documented comments of the editor). I agree this might blow over, but the folks in DC, such as McCain and Lieberman, who are fighting to represent what the legitimate scientific community has to say, need to be prepared in case the special interests try to use this. Hence, the short response I sent out. [Mike Mann]
[Phil Jones] Mike, Depending exactly on what it says I suggest we should do our best to ignore it. E&E is edited ( a very loose use of the word) by Sonia Boehmer-Christiansen, who’s generally involved, in some way, in all skeptic stuff here in Britain. It is rather odd that the email said the two had rerun his (Mann’s) exact analysis and got quite different results. I know I couldn’t do this, as when Keith, Tim and me wanted to do some comparisons with MBH98 a few years ago a few of the series could not be made available. I’m not trying to make any sort of point here, just to state that repeating an analysis with exactly the same data is normally very difficult.
Email 4758, UEA’s Tim Osborn, Oct 2000: “how can we be critical of Crowley for throwing out 40-years in the middle of his calibration, when we’re throwing out all post-1960 data ‘cos the MXD has a non-temperature signal in it, and also all pre-1881 or pre-1871 data ‘cos the temperature data may have a non-temperature signal in it! “
Because how can we be critical of Crowley for throwing out 40-years in the middle of his calibration, when we’re throwing out all post-1960 data ‘cos the MXD has a non-temperature signal in it, and also all pre-1881 or pre-1871 data ‘cos the
temperature data may have a non-temperature signal in it! If we write the Holocene forum article then we’ll have to be critical or our paper as well as Crowley’s!
But here’s the kicker, it’s all big oil and big coal’s fault:
Mann calls the hockey stick “an obscure graph”; other unnamed people have stripped the error bars away, “making it appear more definitive than it was ever intended”; “the entire apparatus for propelling this manufactured scandal on to the world stage was completely funded by the fossil-fuel front groups”
Mann believes the theft of the emails was not the work of a random hacker, but part of a sophisticated campaign. “It was a very successful, well-planned smear campaign intended … to go directly at the trust the public had in scientists,” he insists. “Even though they haven’t solved the crime of who actually broke in, the entire apparatus for propelling this manufactured scandal on to the world stage was completely funded by the fossil-fuel front groups.”…Climate contrarians argued that Mann and his colleagues were concealing their research methods because they had something to hide. In reply, Mann insists that he has been as open as he can about data and methodology, but the aim of these requests has more to do with intimidation than openness. “What they are trying to do is to blur the distinction between private correspondence and scientific data and methods, which of course should be out there for other scientists to attempt to reproduce.
“I think it’s intentional and malicious. It’s intended to chill scientific discourse, to intimidate scientists working in areas that threaten these special interests,” he says. “It’s the icing on the cake if they can also get hold of any more private correspondence that they can mine and cherry pick. It’s a win-win for them.” Why an obscure graph published in a scientific journal should enrage so many people has been the subject of much internet conspiracy (or genuine scientific debate, depending on your point of view).
The original 1998 hockey stick study by Mann and his colleagues did in fact emphasise the tentative nature of estimating past temperatures before the invention of accurate thermometers.
…”When we first published our Nature article in 1998, we went back six centuries,” Mann says. “A year later we published a follow-up going back 1,000 years with quite a few caveats. In fact, the caveats and uncertainties appeared in the title, and the abstract emphasised just how tentative this study was because of all the complicating issues.
“It’s frustrating that to some extent all of that context had been lost and the result has been caricatured. Often the errors bars are stripped away, making it appear more definitive than it was ever intended.”