First, Montford’s book clarifies three weaknesses in the paleoreconstructions, from MBH 98/99 through Mann et al., 08. These include problems with tree rings, the centered PCA analysis, and the R2 issue.
[Response: Really? This is it? The PCA analysis is completely moot as has been shown in the literature Wahl and Amman (2007) and von Storch et al. (2005) and above. And you think this is a big issue in 2010? Please. The 'R2' issue similarly -- the NAS Chapter 9 deals with the issues there very clearly. The basic point is that when you get to the relatively sparse networks further back, the reconstructions don't have fidelity at the year-to-year variability. If that is something you care about (i.e., whether 1237 was warmer or cooler than 1238), then you are out of luck. If instead you are interested in whether the 13th Century was cooler than the 12th C, it's not the right metric to be using. And finally, 'tree rings'? A whole community is just dismissed in your mind? The community that actually pioneered community-wide data sharing in climate science? A community moreover in which the literature has openly dealt with the many issues that arise in dealing with the nature of trees and tree rings -- they are the 'problem'? Again, really?
The points are even more bizarre when you actually look at the latest work that shows that reconstructions without tree rings or off-centre PCA give good reconstructions back centuries and that they aren't grossly different to the ones using tree rings. What more do you want? - gavin]
[Response: This is simply insulting. You have absolutely no evidence that this was the case. The RE/CE statistics are perfectly fine at describing what the authors thought were relevant and have a long history in that field (Fritts, 1976) and as we have seen the PCA issue is moot. The idea that people went looking for 'bad statistics' to fix their results is without merit whatsoever. Please withdraw that claim.]
1. The high level of confidence ascribed to the hockey stick inferences in the IPCC TAR, based upon two very recent papers (MBH) that, while provocative and innovative, used new methods and found results that were counter to the prevailing views. Plus the iconic status that the hockey stick achieved in the TAR and Al Gore’s movie.
[Response: You are misreading the IPCC reports. The relevant claims in the SPM and Chapter 2 in TAR were that 'the increase in temperature in the 20th century is likely to have been the largest of any century during the past 1,000 years. It is also likely that, in the Northern Hemisphere, the 1990s was the warmest decade and 1998 the warmest year'. "Likely" in TAR speak was 66%-90% chance, thus better than 2 in 3, but not as good as 9 in 10. Your characterisation of 'prevailing views' is simply wrong -- the paleo community had long been aware that the medieval period had been very heterogenous (Hughes and Diaz 1994, for instance) and that the peaks did not line up in different records. 'Likely' was the appropriate distinction for the 20th C warming being greater than any century-scale warming in 1000 years, since there wasn't (and isn't) any evidence to the contrary and plenty in support. The only issue that one could reasonably have is the statement about 1998 or the 1990s. Those claims were based on the fact that 1998 was by far the warmest year in the warmest decade in the instrumental record, but without direct evidence that other very warm years in perhaps not quite as warm decades did not match or exceed it. Thus I would have been happier if that part of the statement had been downgraded to 'more likely than not'.
In AR4, the relevant statement was: Average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than during any other 50-year period in the last 500 years and likely the highest in at least the past 1,300 years.. Thus the statement for the last 500 years has been strengthened (which is appropriate given the increase in multiple lines of evidence for that period), and the longer term statement has been lengthened to 1300 years at the same level of confidence as before. Again a reasonable and supportable position. The differences are in the characterisation of the 20C rate of warming, and mainly the highlighting of a specific year in a millennial context. Instead, there is Eleven of the last twelve years (1995–2006) rank among the 12 warmest years in the instrumental record of global surface temperature (since 1850), indicating a move towards a (correct) realisation that the relative warmth of individual years are harder to assess. In toto, I do not see this as a significant downgrading of the conclusions -- you may disagree, but this is not the stuff of conspiracy theories.
In terms of 'iconic' status, showing the results in the SPM seems fair enough, but MBH are not to blame for how images get used or discussed in the media. At all times when the authors themselves were interviewed I have yet to see any statements that were not justified. And as for the AIT, the hockey stick only got a brief mention, and that was by mistake (he used the wrong panel from a Lonnie Thompson paper). This is irrelevant.]
[Response: Science is reproducible and this science was. Mann et al. did not generate the underlying data themselves, they got it from public archives and from asking colleagues -- and that was made public when the previously unpublished work was published. Wahl and Ammann replicated the code (as did McIntyre). There were minor errors in the data listing at Nature, but that was fixed when it was pointed out. Scientists are not obligated to hand-hold people trying to reproduce their results, especially when they have already gone public with a farrago of misstatements in non-peer-reviewed papers (try actually reading MM2003). However, you are making a big error in characterising the culture that existed in 1998. I guarantee I will not find complete public archives for every climate paper that appeared in Nature that year -- are none of those papers 'science'? Nonsense. Replication is not about repetition -- it's about finding new ways to address the same problem. Two ice cores are better than two teams measuring the same one.]
[Response: This is simply not true. There are no 'very likely' conclusions in the relevant sections of TAR (I quoted them above). The only thing they pointed out was in regards to the relative warmth of 1998 and the 1990s in the millennial context which I agree with. They did state with a 'high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries' -- this is equivalent to the strengthening of the statements made in AR4 concerning the last 500 years. They went on to say that the 'committee finds it plausible that the Northern Hemisphere was warmer during the last few decades of the 20th century than during any comparable period over the preceding millennium' -- and in further questions, clarified that plausible was equivalent to 'likely' in IPCC-speak (i.e., less confidence than the statement about the last 500 years). The statement about 1998 and the 1990s was that "Even less confidence can be placed in the original conclusions by Mann et al. (1999) that “the 1990s are likely the warmest decade, and 1998 the warmest year, in at least a millennium” because the uncertainties inherent in temperature reconstructions for individual years and decades are larger than those for longer time periods and because not all of the available proxies record temperature information on such short timescales" which is true enough. Of course, now it is likely that the 2000s were the warmest decade.]
[Response: Again, this is not true. AR4 did in no way 'essentially retract' much of what said in TAR -- for anything substantial concerning the nature of late 20th C warmth the conclusions both in the NAS report and the AR4 report strengthened the TAR conclusions (see the statements above). Perhaps you think that the 'essential' thing is the position of 1998 as the single warmest year? Well, in that case I strongly disagree, this is not 'essential' in anything very much. Much more important in actually understanding the climate are the relations between forcings and responses both globally and spatially over this period, and none of that relies on rankings of individual years. And as for IPCC changing conclusions this has happened many times -- Lindzen used to point to statements about upper tropospheric water vapour for instance that became less confident from the 1990, 1995 and 2001 reports, similarly uncertainty in aerosol indirect effects has clearly grown over time.]
[Response: This is nonsense. The conclusions in the Wahl and Amman papers, and their published code had been public since 2005, so there was no doubt about their results. Steve Schneider was exceptional in many ways, but his journal is not the speediest in terms of turnaround of manuscripts. Weird editorial decisions with respect to the responses to the MM05 GRL paper also did not help. But the authors of the IPCC chapter knew full well that the their statement in the first draft about MM05 was not right -- there weren't any unanswered questions about the impact of PCA centering on the results of MBH98. The WA07 paper was accepted in time for this to be cited (and it was an IPCC-wide decision to decide on the cutoffs, not Keith Briffa's), and it was (no IPCC deadlines were violated). If it hadn't been, it would not have been the end of the world, and I don't see how anything subsequently would have changed. McIntyre has had 5 years to write a comment or a new paper on the subject and he hasn't. As for Briffa talking to Wahl during the final drafting stage, I see nothing problematic with that in the slightest. The idea put forward by McIntyre and Montford that IPCC authors are supposed to sit in purdah while writing the reports has absolutely no basis in fact or in practice. Many people were talked to and many people made suggestions where their expertise was required. The fact is that the AR4 statements in the final version were more correct than in the first draft and that is something people should be happy about.]
[Response: Long well-resolved paleo records are rare -- I doubt that is a surprise to anyone. Should people not use what has been published to get the best characterisation of past climate change? Methods can be independent though, and since your earlier comments seem to revolve around methods, I don't quite get what point you are making.]
[Response: Absolutely untrue in all respects. No, really, have you even read these papers? There is no PCA data reduction step used in that paper at all. And this figure shows the difference between reconstructions without any tree ring data (dark and light blue) compared to the full reconstruction (black). (This is a modified figure from the SI in Mann et al. (2008) to show the impact of removing 7 questionable proxies and tree ring data together). In addition, there are many papers that deal with issues raised by MM -- Huybers (2005), von Storch et al. (2005), Rutherford et al. (2005), Wahl and Amman (2007), Amman and Wahl (2007), Berger (2006), etc.
Judith, I implore you to do some work for yourself instead of just repeating things you read in blogs. (Hint, not everything on the Internet is reliable.)]
[Response: The divergence problem is well known. And I absolutely disagree that the IPCC graphs are 'misleading.' How perchance were you misled? The picture on the 1999 WMO report cover has nothing to do with IPCC, and frankly was completely unknown until November last year. Yet an incomplete caption on a report that no-one knew about is the biggest scandal in climate science? Get real. I'm with Muir Russell on this one. There is nothing wrong per se in splicing records together to get a continuous series -- for instance, I have just done the exact same thing in creating a series of solar forcing functions for climate model runs -- but these things should be clearly explained. The divergence issue is predominantly an issue for the tree ring density measurements (Briffa et al.), and while there is some reason to think that is a unique phenomena, it remains unresolved. So, feel free to ignore the Briffa et al. curve if you want. This is not a general issue and doesn't affect the MBH and Mann et al. (2008) conclusions at all.]
[Response: Oh please. Why didn't the first multi-proxy paper deal with all issues and try all methodologies and come to all the conclusions? Because that is not the way science works. People try new things, issues arise, issues are dealt with and a more sophisticated understanding emerges. Some data is used, more data is gathered and more complete pictures arise. No single paper is ever perfect -- and I'm sure if any of your papers (or mine, for that matter) got the attention that has been paid to MBH98 there'd be all sorts of potential issues as well. But you are again overstating the conclusions of those early papers, and there have been no extraordinary efforts to defend them. It is quite the contrary, there have been many and multiple extraordinary attempts to discredit them (unless you think Congressional review is 'ordinary'). No one is against efforts to learn from outside statisticians -- that is just a strawman. People are against politically-driven hack jobs purporting to be analyses but that don't even bother to work out what the consequences of any different choices might be. All of the data in Mann et al. (2008) is online, as is all the code -- where are the outside statisticians who are clamouring to have their ideas heard? They are welcome to try and do a better job.]
[Response: The reason this has become 'contentious' has nothing to do the MBH and everything to do with people not wanting climate change to be a problem. Icons that arise for whatever reason attract iconoclasts. Noise in the blogosphere does not correlate to seriousness in climate science. As your comments make abundantly clear, you have very little knowledge on this issue and have done no independent investigation of the wild claims being made. Yet the more smoke there is, the more you appear to want to blame MBH for the fire. A 'certain amount of spin'? Seeing conspiracies everywhere you look is not 'spin,' it is paranoia. Real scientific controversies get resolved in the literature for the people who actually care about getting things right. For those that don't, continued repetition of long debunked talking points seems to be their only tactic. I, for one, am pretty tired of that and heartily bored of pointing them out.
The fact of the matter is that we are far beyond the point where people need to either s*** or get off the pot. Continuing to whine about what selection rules were used in a PCA analysis 12 years ago without coming up with any constructive alternative, continuing to complain about a centering convention that makes no difference whatsoever, continuing to moan about error analyses being inadequate without doing a single stitch of work to improve them... enough, already! Science moves forward because people do actual work. Nothing happens when people just sit in a room and [edit] complain about the state the world. The people who are actually publishing in this field are doing all of the things you seem to think are being ignored, while they people whose work you are reading are doing nothing but complain about how they are being ignored. I’m very confident about which group will make the most progress in future. – gavin]
185
Gavin, the post I made in #167 was a summary of Montford’s book as closely as I can remember it, sort of a review. I did not particularly bring in my personal opinions into this, other than the framing of montford’s points. So asking me to retract a point made in a book in a review of that book is, well, pointless. your attempt to rebut my points are full of logical fallacies and arguing at points i didn’t make. As a result, Montford’s theses look even more convincing. Once you’e in a hole, you can try to climb out or keep digging. Well keep digging, Gavin. My final words: read the book.
[Dear Readers, Gee, I do so wish those were really her final words, but the chances of that are slim to none, I would imagine.]
[Response: Thanks for passing by. In future I will simply assume you are a conduit for untrue statements rather than their originator. And if we are offering advice, might I suggest that you actually engage your critical faculties before demanding that others waste their time rebutting nonsense. I, for one, have much better things to do. - gavin]
190
I encourage people to read Judith Curry’s comment #185 two or three times.My jaw drops closer to the floor on each re-reading.
Let’s see … since Dr. Curry was only regurgitating Montford’s arguments without stating that she agrees with them (bad news for Judith – the intranets are all hooked up like altogether like and you *have* supported his points elsewhere), Gavin’s responses are invalid because he addressed them to Judith rather than Montford.
Therefore Montford’s argument is strengthened. This is an ad hom argument – Judith attacks Gavin’s style, not substance, and without addressing a single factual point made by Gavin, claims victory for Montford as a result.
Meanwhile, though she insists she’s not stating whether or not she agrees with Montford’s points, she tells people “read the book.” Why, Judy, unless you think Montford’s claims are true?
Meanwhile my response to Judy … read your point #7. Then read Mann ‘08. Then re-read your point #7 and, if it’s still not clear to you why Montford’s lying, repeat until it sinks in.
Thank you.
205
To Peter Webster,To repeat, Judith Curry first states that Tamino’s review contains (IN HER OWN WORDS) “numerous factual errors and misrepresentations, failure to address many of the main points of the book.”
Now some, not Eli, he hastens to add, would think that an eminent scientist, expert in closely related matters, making such an accusation would have an excellent grasp of the background material.
And indeed, when challenged Prof. Curry provides a list of many points, which most, not Eli, he hastens to add, would think were her views of what these factual errors are. Indeed, she characterized her actions by “so I am taking a few moments to clarify the weaknesses in Tamino’s review”
Yet, when challenged, Prof. Curry demurrs that none of these reflect her personal opinion but were rather points that Montford made in his book, on which, of course, she has no opinion, but since gavin and tamino chose to rag on the rich dish she put on their plate, why, of course, Montford must be right.
And, you, of course, chime in saying that Gavin was mean.
Sorry Peter, but that is a bit much. There comes a point at which the dissembling is no longer amusing, and Prof. Curry is rapidly approaching that point. Were Eli Gavin, which he is not, both hasten to add, he would not have withdrawn a word.
[You gotta love Eli!]
Link: http://www.realclimate.org/index.php/archives/2010/07/the-montford-delusion/comment-page-4/#comments
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