2011-09-29 21:43:26McIntyre's new target
grypo

gryposaurus@gmail...
173.69.6.13

Not sure if anyone realizes it, but the statisical super geniuses at CA have picked a new target.  Andrew Dessler.

I count 8 threads since earlier this month.  Unfortunately, most people (including myself) have no way to check the validity of these (also Troy_ca's) arguments.  Nor do I know how to understant Nick Stokes' rebuttals (or even if they are rebuttals) within the comment section.  Part of Mcintyre's magic, is his ability to take his statistical ability (whether right or wrong) and transfer that into rhetoric that the normal person can understand.  Because this is all pretty much all un-reviewed and unfocused, it is the kind of thing that hurts people's understanding of the science, and more importantly, works to undermine the experts in the field in favor of continous math exercises on the internet.   While I doubt any of this will make much of a dent in the real science, it effects the public understanding and can be very damaging.  As an aside, even if I were a skeptic, I would find this method of 'doing science' to be completely unacceptable.  I cn't see how it would further anyone's knowledge.

 

We've seen the effect McIntyre can have on the debate.  He's pretty much ruined people's understanding of paleo.  So I'm not sure how this can go ignored.  The last thing the world needs is for the public to reject all cloud science and scienctists when we are getting really close to having a better understnading of it.

2011-09-29 22:04:30
nealjking

nealjking@gmail...
84.151.44.222

Isn't this sort of thing Tamino's bailiwick?

2011-09-29 22:14:42
grypo

gryposaurus@gmail...
173.69.6.13

I'm not sure.  To be honest, it's a complete mess.  The arguments need to be disentangled.  The only one I can understand is the choise of using all Ceres series instead of including ERA clear sky.  To an onlooker, this just looks like "Anything but what Dessler says!"

 

I can't see how anyone looking at this, even those from a techinical background, can be anything but thoroghly confused.

2011-09-29 23:18:30
grypo

gryposaurus@gmail...
173.69.6.13

I was thinking someone who knows the data sets and cloud literature would help people understand this better.  Otherwise it's just another person doing math on the internet.  The idea would be create a narrative based on reality and expert knowledge.  Otherwise the truth gets lost in piles of nonsensicle blog posts.  People can just pick whichever one they fancy because they don't understand them.  Probably Dessler would be the best.  Or Perhaps Chris Colose knows the lit?

2011-09-29 23:42:21comment
Robert Way

robert_way19@hotmail...
134.153.162.53

McIntyre is a tough person to target... Even for the experts. The fact of the matter is that a lot of the points he brings up are valid the challenge is that he associates them with too much skepticism. He finds a mistake and suddenly its a conspiracy whereas a normal person would call it a reasonable mistake. But I wouldn't want to go up against that group, between them there is a lot of statistical power to manipulate and make the data say what it needs to say.

2011-09-29 23:48:17
nealjking

nealjking@gmail...
84.151.44.222

Real data and statistics are a subtle subject.

I try to stay away from both, as far as possible.

2011-09-30 02:31:14
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Make no mistake, there is some social networking going on here behind the scenes (does that group who hack mega corporations also hack emails of people like McIntyre?).  Roy and McIntyre have been in touch by email, Spencer says as much on his blog-- so who knows exactly how much discussion has occurred between them, probably a lot.  

Recall that Dessler recently dessimated Lindzen in a debate, overturned a skeptic paper that claimed tropospheric water vapour is decreasing (it isn't)  and now he has had the temerity to use observations to show that the cloud feedback is likely positive.  The last one is key, that is their last stand, that and this mythical internal forcing mechanism that changes cloud cover.  So yes, they are pissed.

They went after Trenberth a while ago, but they soon lost interest on that one, not enough stats involved probably.  But Dessler's new work does involve stats.

Now as we all know stats can be manipulated.  What I find ridiculous is that McIntyre et al. are not real auditors, that is just a sham, a PR stunt.  More importnantly though and more ridiculous is that they insinuate (dog whistle, feeding fodder to skeptics) or make accusations of mendacious behaviour by those they audit.  But recall that McIntyre has a history of shall we say playing loose with the facts-- for example, seeking out those chronologies (cherry-picking) that showed a HS and then claiming that Mann's method prodiced a HS from red noise-- i..e., it was designed to produce a HS.

As for the claims being disorganized, no surprise there, they are doing it on the fly and throwing as much mud in the hopes that something, anything sticks.  But the more disorganizd and confused they are all the better for the good guys.

But going by Roy's cocky letter of encouragment to Dessler, they may have found something-- not Spencer, but some sharp people with a propensity to twist stats to character assasinate people like Dessler and Mann.

AGAIN, THIS IS SO NOT ABOUT THE SCIENCE

2011-09-30 07:06:28
grypo

gryposaurus@gmail...
173.69.6.13

I actually think taking these people on directly is NOT the way to go either.  They will just double down on their blogging.  Nothing accomplished.  I just fear that they will take over the debate and apply the same narrative that they did to paleoclimatology.  So I do think some response early on is necessary.  It surprizes me that Dessler hasn't yet.  He's not shy about showing up on blogs and seems to have a clue about public perception.   

2011-09-30 07:35:50
Rob Honeycutt

robhon@mac...
98.207.62.223

In•sid•i•ous: adj.  treacherous; crafty.  See: McIntyre

2011-09-30 12:33:50
Alex C

coultera@umich...
67.194.28.202

>>>does that group who hack mega corporations also hack emails of people like McIntyre?

Typically groups like Anonymous hack those they see as threats to sharing of information (they're highly sensitive about censorship).

Well, Anonymous is like that anyways.  Many other groups are more cynical, though whether they'd go after small fries like McIntyre is beyond my ability to predict.

2011-09-30 12:58:24
jyyh
Otto Lehikoinen
otanle@hotmail...
85.76.182.106

Imho, they seek the personal scientific weaknesses of a writer of a paper on climate change and attack those. F.e., if one is poor at net security, they attack on this...

My experience of McIntyre was short but telling and that's where I got one of the standard responses of the deniers: "I'm not interested in auditing papers that are doubtful of the consensus view on climate change", but perhaps it was not in just those words. Then the discussion was diverted into Lysenkoism. It seems to me the people who audit papers in there take differenent attitudes while doing that, they treat the papers either as engineers, frequentists, bayesians, and use the approach that makes their target paper look the worst possible, sometimes even taking the 'controversy' to the level of spectroscopic quantum effects so one better be ready to prove (with quantum physics) that CO2 absorption of IR is transferred to other molecules in the atmosphere, the spectral broadening, and the spectres of individual CCN elements (the work started at the CLOUD experiment), and their effects on cloud albedo (on a natural environment). Their approach is that measurements made in a natural environment are not enough for climatology to be called a science, they want to start with the first principles (which they would likely twist if thay could.) All crooked and skilled, yes.

2011-09-30 13:49:40Out of curiousity...
John Hartz
John Hartz
john.hartz@hotmail...
98.122.98.161

How do McIntyre et al explain away the multiple lines of evidence such as the melting of the Arctic Ice Cap, the northward migration of the pine beetle, the melting of North America's alpine glaciers., etc. ? 

Perhaps "lines of evidence" is their soft underbelly? 

2011-09-30 14:18:26John Hartz
jyyh
Otto Lehikoinen
otanle@hotmail...
85.76.182.106

I'd guess one approach they could use would be to treat them individually f.e. in this style:

1)melting of the Arctic Ice Cap,

Please show that the microwaves by satellites do not effect the brittleness of the ice so that it breaks more easily (show a study in which a slightly salted ice is radiated minutely and prove it doesn't melt quicker (statistically almost impossible), while also proving the ice breakers won't disturb the natural development up there (impossible)

2)the northward migration of the pine beetle,

Please prove the population currently outbreaking northwards hasn't experienced a mutation affecting its cold tolerance (take a sample of historical 1950's collection, sequence the whole genome of that one, prove that the mutations aren't affecting the cold tolerance (impossible since one cannot prove which individual had the assumed mutation first))

3)the melting of North America's alpine glaciers

Please show the temperature records around the glaciers eversince they have melted and prove humans have affected it (impossible since good temperature records around glaciers are absent in the 1950s), or please prove increased winds are not affecting (moving goalpost)

2011-09-30 15:18:20
Ari Jokimäki

arijmaki@yahoo...
192.100.112.202

McIntyre and his bunch don't even try to explain the whole thing. They only want to show that science is not to be trusted. Doubt is their product.

2011-09-30 15:19:36
Ari Jokimäki

arijmaki@yahoo...
192.100.112.202

Well, actually they don't even want to show that science is not to be trusted - they just want to make it look like that.

2011-09-30 16:36:52Dessler the next Mann
Glenn Tamblyn

glenn@thefoodgallery.com...
121.216.197.108

So how do we prevent Dessler from becoming the next Michael Mann. And when I say we I don't mean just SkS. This perhaps needs a coordinated response from the Dessler, the Rapid Response Team, RealClimate, Tamino and other gun statisticians. People who can take McIntyre on at his own game. Too often we end up like the guy sticking his fingers in the dyke without realising that the dyke has so many holes because a team of sappers is undermining the dyke. This smells like that. And if we want to avoid a repeat of the disaster of the Hockey Stick - and it was a disaster - then everyone needs to act quickly. Time for the pro's to make McIntyres life miserable.

John C, Time to get those emails flying.

2011-09-30 16:45:29
nealjking

nealjking@gmail...
91.33.125.150

Principally, Dessler has to take them on. Everything else is secondary.

2011-09-30 16:59:12
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.32.23

I followed Grypo's link and they're still droning on about "Yamal" and the "Hockeystick." Pathetic. 

2011-09-30 17:22:06
Glenn Tamblyn

glenn@thefoodgallery.com...
121.216.197.108

I disagree Neal. Although Dessler is the target, it needs a coordinated response. Have we learned nothing from the HS Affair. Termites can undermine your house. When the termites are intelligent, motivated and coordinated, that is actually scary. We keep underestimating how well the black-hats actually 'get' media/PR/psychology etc. Because they are MOTIVATED to get it. For us opposing them is a somewhat academic exercise in polemics. For them it is deeply psychologically visceral. Deep down we think they are charlatans. Yet as time goes by I am becoming more convinced that they are deeply passionate about this. Passion based on delusion perhaps - thats what denial is. But passionate nonetheless. While Dessler is busy at his day-job of climate science, for the Black Hats, this IS their day job. And their passion.

This sort of thing is potentially just as serious - the next cause celebre, the next tactic for another decade. The problem 'our side' - I hate that sort of thinking - face is that deep down we still think that right will triumph.

Well tell Gulliver that, lying there on that beach, captured by the Lilliputians. Or the mighty US Army, taking on the mere Viet Cong. Unfortunately, the enemy determines the battleground, because deep down we don't think we are in a war. And as Sun Tsu may have said (I'm sure he would have if I hadn't thought of it first), 'if your enemy chooses the field of combat, your cause is lost'.

Sometimes wars are won by the recognition that you need to bring overwhelming firepower to destroy one target, then move on to the next target. Nice guys don't win wars, bastards do.

2011-09-30 17:24:51
nealjking

nealjking@gmail...
91.33.125.150

You're not going to make much progress if Dessler doesn't get into it.

2011-09-30 21:02:13
grypo

gryposaurus@gmail...
96.253.55.56

At some level Dessler is necessary, just for the fact that the choice of data sets is being questioned, so he would need to defend it.  In essence, he is being accused of cherry-picking, without those words being used (by McIntyre), but that's the narrative.

Dessler 2010 made the curious decision to combine ERA clear-sky with CERES all-sky to get a CLD forcing series. This obviously invites the question about the impact of using CERES clear-sky in combination with CERES all-sky to calculate the CLD forcing series. One would have thought that this is the sort of thing that any objective peer reviewer would ask almost immediately. Unfortunately, as we’ve seen, climate science articles are too often reviewed by pals. Nor, to my knowledge, has the question been raised in the climate community.

2011-09-30 21:48:11
jyyh
Otto Lehikoinen
otanle@hotmail...
85.76.170.250

cross-validation of the clear sky datasets would be a reason to do it so, possibly Dessler has done that but not included it (maybe there wasn't space in the paper)

2011-09-30 22:05:26
Steve Brown

brownsg@gmail...
91.220.25.25

Beyond publishing another myth rebuttal relating to anything McI comes up with, I don't think SkS should need to do any more.  It is Dessler's duty to defend his own work.  If any McI accusations find its way into the mainstream media then SkS can take a more active role in challenging them.

At the end of the day, the overwhelming majority of the planets population couldn't care less about Climate Audit, let alone try and follow the tortuously anal debate that goes on there.

2011-09-30 22:39:19
grypo

gryposaurus@gmail...
96.253.55.56

jyyh

 

There is no indication of another validation test in the paper, I believe Dessler defended the use in the paper by citing other work on why using both CERES sets isn't as useful.  For whatever reason, they believe troy_ca's postings dispute this.  i can't figure out why.  This is where the confusion begins and high statistical content dominates the debate.

 

Steve,

At the end of the day, the overwhelming majority of the planets population couldn't care less about Climate Audit, let alone try and follow the tortuously anal debate that goes on there.

Very true.  But McIntyre's magic is in forming narratives that permeate through to the mainstream.  I agree SkS has limited ability to do anything about this.  Just brainstorming here.

2011-10-01 01:09:22What the heck is wrong...
John Hartz
John Hartz
john.hartz@hotmail...
98.122.98.161

with John Cook sounding out his peers on this matter?

2011-10-01 01:26:44comment
Robert Way

robert_way19@hotmail...
134.153.162.53

Rob said: I followed Grypo's link and they're still droning on about "Yamal" and the "Hockeystick."



I don't mean to be the pessimist of the group here but Mc brought up some very good points about the original hockeystick. The confidence affirmed to it by many on our side of the debate was vastly overstated and as has been shown in the recent literature greater variability on the centennial scale exists than was shown. The statistical methodology used by Mann did rely too much on tree rings which still are in debate over their usefulness to reconstruct temperature and particularly their ability to record low-frequency temperature variations. I've personally seen work that is unpublished that challenges every single one of his reconstructions because they all either understate or overstate low-frequency variations. My personal experience has been that Moberg still has the best reconstruction and his one does show greater variability. That's why I don't like to talk the HS stuff, because I know a lot of people who have doubts about the accuracy of the original HS. Just like we complain about skeptics like Pielke and Christy etc letting their work be miscontrued, Mann et al stood by after their original HS and let others treat it with the confidence that they themselves couldn't assign to it. They had just as much of a responsability to ensure their work was used to promote properly just as Christy et al do. It is a tight rope we must all walk afterall.

2011-10-01 01:36:05Robert Way
John Hartz
John Hartz
john.hartz@hotmail...
98.122.98.161

The plot thickens. Thanks for the insights.

2011-10-01 02:15:14
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Robert,

I agree, but only to a point.  McIntyre was not the only one who saw issues with that seminal work, so please do not give him all the credit (and also do not forget that his papers have isues too).  First and foremost it was a semial work remember.  One cannot expect it to be perfect.  You and I both know that even when the weaknesses and problems were addressed, the impact was for all practical purposes trivial. Indeed, the HS shape has been found in many other paleo reconstructions using different methods and data.  And Mann et al were quite responsive, MBH98 was followed by Mann et al. 1999, and there have been several publications refining the data and techniques by Mann et al since then. Nobody really references MBH98 anymore (except those of us who are still stuck in 1998), as the science has moved on, but had MBH98 not been written science now would not have advanced as much.

You and I know what McI's game is-- it is not advancing the science or the pursuit of truth. Do you disagree with this post at RC Robert?

As for the allegation about "Mann et al stood by after their original HS and let others treat it with the confidence that they themselves couldn't assign to it."  I canot speak to that, but that is certainly not my perception.  Their papers are loaded with caveats.  They did address concerns raised by the investigations.  MBH98 paper has been under attack form the get go by those in denial and by "skeptics".

 

 

From Wikipedia

 

2011-10-01 02:20:09
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Robert,

"They had just as much of a responsability to ensure their work was used to promote properly just as Christy et al do. It is a tight rope we must all walk afterall.

On that I agree, but drawing parallels between Christ and Spencer and Mann et al. is stretching the analogy too far; they really are very different in terms of the quality of science and their pursuit of truth and how they conduct themselves.

Dessler is now Stevie's new target-- this is just plain ridiculous character assassination and feeding the "skeptics" foddder by McIntyre and his supporters (which inlcudes Mosher, no?). Dessler may have erred, but what McI is doing is most definetly not how one addresses problems in science!

2011-10-01 02:38:11
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

Yeah the big difference between Spencer/Christy and Mann et al. is that the former trumpeted their results as proof that the surface temp record and AGW theory were wrong.  I don't think the 'hockey stick' was trumpeted nearly as much by its authors.  I've only seen it referenced as one small piece of evidence, except by fake skeptics, who want to believe the entire AGW theory hinges on the hockey stick (when ironically, were the hockey stick correct, it would infer low climate sensitivity).

2011-10-01 03:24:03
grypo

gryposaurus@gmail...
96.253.55.56

Robert, why Moberg?

 

And I'm not actually arguing whether McIntyre or Troy_ca is correct or not.  What I am arguing is how a small group of non-expert skeptics frame the debate around an entire branch of science wthout any real expert review system to seperate out the crap .  THese guys did the same thing to Steig about the Antarctic temps.  In that case, they turned out a paper that will make a difference, and as it turns out with Steig as a reviewer, but the aftermath was a disgusting assault on his character.  It didn't seem at all like they cared they'd just added to the knowledge base.  It seemed like they wanted to influence the public opinion, certainly not expert opinion.  In short, right or wrong, this is bad for science and the debate.

 

As for what McIntyre found in the original Mann paper (not that I want to rehash this), reviewers for the paper - Huybers said that M&M overstate the problems with PC1 hockey stick mining.  Von Storch said something similar.  This comes up again in the recently released reviews of the Wegman Report shows another stats guy rejects the more egregious accusations of statisical malfeasance by Wegman (based on evidence that looks exactly like McIntyre's original paper.  Fancy that.)

2011-10-01 05:36:52
Robert Way

robert_way19@hotmail...
134.153.162.53

I don't think making a direct comparison to Pielke et al was correct because they're clearly not equal and opposites. Mann's science is mostly good and I certainly think that his papers have discussed most of the caveats. However his reconstruction failed certain statistics (can't remember if it was r2 or RE) and even his newest reconstruction doesn't validate past 1400 if you don't include disputed series (which I have no idea why he's including them at all). Lets make this clear. There is a hockey stick shape in the data, but the original hockey stick still used the wrong methods and these methods were defended over and over despite being wrong. Just because a better analysis (Wahl and Amman 2007) using the same data shows very little difference doesn't change the fact that the technique was wrong. PCA isn't the best choice anyways... but that's irrelevant.

This is where my problem lies:

From RC

“Contrary to MM’s assertions, the use of non-centered PCA is well-established in the statistical literature, and in some cases is shown to give superior results to standard, centered PCA… For specific applications of non-centered PCA to climate data, consider this presentation provided by statistical climatologist Ian Jolliffe who specializes in applications of PCA in the atmospheric sciences, having written a widely used text book on PCA. In his presentation, Jollife explains that non-centered PCA is appropriate when the reference means are chosen to have some a priori meaningful interpretation for the problem at hand. In the case of the North American ITRDB data used by MBH98, the reference means were chosen to be the 20th century calibration period climatological means. Use of non-centered PCA thus emphasized, as was desired, changes in past centuries relative to the 20th century calibration period.”

I. T. Jolliffe, Principal Component Analysis, Springer-Verlag, New York, 1986.

Comment by Dr. Jolliffe at Tamino’s
“…It has recently come to my notice that on the following website, http://tamino.wordpress.com/2008/03/06/pca-part-4-non-centered-hockey-sticks/ .. , my views have been misrepresented, and I would therefore like to correct any wrong impression that has been given… In reacting to Wegman’s criticism of ‘decentred’ PCA, the author says << that Wegman is ‘just plain wrong’ and goes on to say ‘You shouldn’t just take my word for it, but you *should* take the word of Ian Jolliffe, one of the world’s foremost experts on PCA, author of a seminal book on the subject. He takes an interesting look at the centering issue in this presentation.’ >>
It is flattering to be recognised as a world expert, and I’d like to think that the final sentence is true, though only ‘toy’ examples were given. However there is a strong implication that I have endorsed ‘decentred PCA’. This is ‘just plain wrong’.

…(my talk)…It certainly does not endorse decentred PCA. Indeed I had not understood what MBH (Mann 1998) had done until a few months ago. Furthermore, the talk is distinctly cool about anything other than the usual column-centred version of PCA. It gives situations where uncentred or doubly-centred versions might conceivably be of use, but especially for uncentred analyses, these are fairly restricted special cases. It is said that for all these different centrings ‘it’s less clear what we are optimising and how to interpret the results’.

I can’t claim to have read more than a tiny fraction of the vast amount written on the controversy surrounding decentred PCA (life is too short), but from what I’ve seen, this quote is entirely appropriate for that technique. There are an awful lot of red herrings, and a fair amount of bluster, out there in the discussion I’ve seen, but my main concern is that I don’t know how to interpret the results when such a strange centring is used? Does anyone? What are you optimising? A peculiar mixture of means and variances? An argument I’ve seen is that the standard PCA and decentred PCA are simply different ways of describing/decomposing the data, so decentring is OK. But equally, if both are OK, why be perverse and choose the technique whose results are hard to interpret? Of course, given that the data appear to be non-stationary, it’s arguable whether you should be using any type of PCA.

I am by no means a climate change denier. My strong impressive is that the evidence rests on much much more than the hockey stick. It therefore seems crazy that the MBH hockey stick has been given such prominence and that a group of influential climate scientists have doggedly defended a piece of dubious statistics. Misrepresenting the views of an independent scientist does little for their case either. It gives ammunition to those who wish to discredit climate change research more generally.

[THIS IS THE EPITOME OF HOW I FEEL-Robert Way]

…distinguishing between the hockey stick and the MBH hockey stick is the key issue. The latter is where the problem lies because of what I deemed ‘dubious statistics’. It is this one particular paper, and in particular the defence of the technique used as recently as this year, which has caused so much grief…

The only reason I got involved is because the ‘dubious statistics’ were still being defended this year and my name was being used in support. “

Ian Jolliffe, PH.D Statistics

I. T. Jolliffe. Principal component analysis. In: Encyclopedia of Statistics in Behavioral Science, (eds. B. S.Everitt and D. C. Howell), Vol. 3, 1580-1584, Wiley, New York, 2005.

Tamino
"Dr. Jolliffe has convinced me that applying decentered PCA invalidates the selection rules which are applied when choosing which PCs to include in one’s model. But the “relevant” (hockey-stick shaped) PC would have been included anyway, applying valid selection rules to centered PCA. And the PCs which are omitted (because they’re suppressed by the method rather than the statistics) don’t seem to correlate with temperature in the calibration interval. Therefore it seems to me that the method is flawed, but the flaw has little or no impact on the final result."


With respect to Steig,
I think he didn't handle the whole issue well at all. He fed the fire. Truth is that his method did spill over some of the warming into places where it wasn't. JeffID and them had their method prolly reduce the warming a bit. At the end of the day Steig really fed the fire with those posts at RC and so on... These guys really go for blood.

2011-10-01 05:59:24
nealjking

nealjking@gmail...
91.33.125.150

- I don't follow all the details, but my impression is that Mann and buddies have sometimes gone out on a limb when that was unnecessary and ill-advised. My impression is that Mann, for all his technical ability, is sometimes his own worst enemy.

- Similarly, with regard to "hiding the decline" in Climategate, I am left with the impression that the real question is, Why would you believe the tree-ring proxies at earlier times when you KNOW that they didn't work properly in the 1990s? I guess there is a good answer to that, but no one has ever given it to me.

I believe a good 50% of the game is being able to avoid booby traps. Because the science is at the edge of ignorance, mistakes WILL be made. The question is, How do you avoid putting your foot in the traps? I think Mann (and maybe Steig) are examples of how NOT to proceed.

2011-10-01 06:00:50Onto other stuff
Robert Way

robert_way19@hotmail...
134.153.162.53

So responding to other stuff.

Mann 2008 CPS

"As an exercise assume you start with 1000 sets of random very noisy set of data which swings up and down by 4 degrees C and you average them.  You should get a relatively flat line with wiggles of a magnitude much smaller than any of the individual peaks.

If you take the same random data, calibrate its endpoint to today’s temperature (offset it so the end matches today’s temperature) and then sort it (throw data out) so that only data which correlate to a temperature rise at the end 5% of the dataset remains. Then you average the remaining data you would get a relatively flat line with an upward spike at the end. The averaged data would have an end spike which would almost certainly be of greater magnitude than the rest of the curve"

This is from JeffIDs site and although I do think he's a douche he does bring up a good point. Even with a hockey stick in the dataset the method will result in excluding datasets which support the hockey stick the least.


I think that the challenge in this whole debate is that Mc et al are looking to find any excuse they can to distort the truth and milk and manipulate it as best as they can. Mann et al (and Steig et al) gave them excuses to quite often. Kill them with kindness or kill them with your brilliance, don't leave yourself open to criticism when people are watching.

Re Moberg:

See his 2008 paper:
Analysis of Moberg et al (2005) hemispheric Temperature reconstruction. Climate Dynamics.
"Hence, the M05 approach does not routinely inflate low-frequency variance. In our experiment, the M05 approach performs better in the spectral domain than CPS when applied to forced climate model simulations. The results underscore the importance of evaluating the variance spectrum of climate reconstructions."

From Moberg and Brattstrom (2011)
"The often used calibration approach of regressing the instrumental data on the proxy data (here called DOLS) leads to a climate reconstruction with noticeably less temporal variability than the calibration target data. This attenuation will affect variability on all time scales, and this is certainly not desirable. Underestimation of past climate variability would, if reconstructions are used, e.g., in subsequent studies aimed at empirically estimating the climate sensitivity to external forcing, lead to attenuated estimates of this sensitivity. Performing the regression ‘the other way around’, i.e. regressing proxy on instrumental data and then inverting the slope (IOLS), will instead exaggerate the reconstructed climate signal amplitude in proportion to the level of noise in the instrumental climate data."

There is also unpublished work (submitted and retracted for a practical reason) that has shown me that most climate reconstructions have either over estimated or under estimated centennial scale climate variability. Moberg's performed the best on that scale.


I agree with Neal on this issue.

2011-10-01 06:08:41
Steve Brown

brownsg@gmail...
80.177.115.133

I saw McI in action last year at the Guardian Climategate debate (Tim Lambert was gracious to turn my review into a post at Deltoid).  He came across as quiet, softly spoken and nervous.  He stated during the debate that if he was in government he would certainly be promoting the regulation of greenhouse gas emissions because the evidence of its impact is there.  He's undoubtedly a very bright bloke who could make a positive contribution.  Unfortunately, he seems to have enveloped himself in some sort of grudge match against a few individuals.

2011-10-01 06:16:17
nealjking

nealjking@gmail...
91.33.125.150

Steve,

Your story supports one of my views on life: "90% of all decisions are made for political reasons; 90% of the remainder are made for fiscal/budgetary reasons; the remainder are made for other (long-term benefit, short-term benefit, esthetic, etc.) reasons. Unfortunately, the last is only 1%."

2011-10-01 06:26:35
Rob Honeycutt

robhon@mac...
98.207.62.223

Steve...  Jeez!  Let's get McIntyre a job in government!  Quick!!

2011-10-01 06:34:26
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Hi Robert,

Gee, I am kinda grouchy today (maybe has somethingt o do with our youngest being up for hours last night convinced that there was a monster in the house)...

Anyhow, you might be surprised to know that we are in agreement on quite a few things.  We also have to try and put ourselves in Mann et al's shoes-- the constant attacks, the constant innuendo, the insinuations, the antagonism from McI et al. is truly astounding.  How well would your or my work have withstood such ridiculous and unrelenting scrutiny Robert? 

I have no doubt that Mann and especially Steig (yes, he did nto deal with the entire Anarctic fiasco well, but then neither did Condon and the lead author Ryan O’Donnell, in fact Ryan behaved the worst of all of them), have made mistakes and, undere duress and pressure,  have on occasion either made poor choices or said stupid things.  I don;t want to defend that, but I can't imagine that you or I would deal with that kind of unrelenting pressure as well as they have. 

I think that is where the stubborness on Mann et al's part has come in-- if people are being constructive, have a genuine interest in advancing the science and are not duplicitous with you, then you are much more likely to accept their critique. 

McIntyre has failed on all those counts.  He has in fact defamed and some might even say libeled Briffa and Mann and Hansen, and recently Trenberth and Dessler, amongst others.  I am sick of his games, ego trips and mendacity and insiduous actions, and so are many others.

You wrote a lote in your posts, and I do not have time to respond to it all now. Regarding

"I think that the challenge in this whole debate is that Mc et al are looking to find any excuse they can to distort the truth and milk and manipulate it as best as they can. Mann et al (and Steig et al) gave them excuses to quite often. Kill them with kindness or kill them with your brilliance, don't leave yourself open to criticism when people are watching."

I agree, but I'm afraid in the real world actually having to be the person who is responsible for doing that is infinitely more difficult than typing it here. We really ave to try hard to remember that.

2011-10-01 06:52:32
nealjking

nealjking@gmail...
91.33.125.150

Albatross,

I think all of us here at SkS are on Mann's side, not McI's.

Nonetheless, it is necessary, if you want to improve, to admit that it is your own side that is sometimes falling down. Insisting on results that you cannot back up 100% is "leading with the chin". One CANNOT do that sort of thing: One must pay McI et al. the acknowledgement that they will detect that error and go for the throat.

2011-10-01 08:20:52Robert Wray
Tom Curtis

t.r.curtis@gmail...
112.213.153.232

1)  I agree you (and Michael Mann) that there are problems with the statistical procedures in MBH98, but I also agree with Michael Mann that:

a)  Their effect was significantly overstated by McIntyre; and

b)  The statistical procedures recommended and implimented by McIntyre are far more dubious than those used by Mann.  In particular, truncating the analysis to the first two principal components clearly leaves out relevant data, and McIntyre's reconstruction prepared in critique of Mann is simply absurd as a result.

(b) is a very relevant point.  Mann was not just being criticized for using a particular technique.  His primary result was being challenged by a clearly flawed method.  Early in the controversy he was not being placed in a position where he could stop using his technique and use a better one, but being challenged for not using a worse technique.

Further, MBH98 was opening up a new field of research.  Anytime that happens mistakes are made.  Scientists recognise those mistakes, improve their techniques and move on.  Idealogues stick with the flawed techniques, or continue attacking them long after they have been abandoned.

 

2)  JeffID's criticism of is in fact irrelevant.  It assumes that it is a reasonable supposition that most of the proxies vary randomly with respect to temperature.  Using CPS on a set of proxies containing a genuine consistent signal will reproduce that signal.  IF some of the proxies are arbitrary with respect to the signal, that will cause the resultant reconstruction from composition to be too flat, but scaling will largely eliminate the problem.  As the proxies are chosen for a known, physically based covariance with temperature, the basic suposition of jeffID's critique is therefore void.  That is in fact shown by the fact that Mann et al 2008 did not produce a flat reconstruction.

 

3)  I am inclined to agree with you on Moberg.  In my case this is because their reconstruction has a surprising similarity to the concentrations of CO2 in the atmosphere as revealed by Antarctic core samples.  I believe that with caution (due to land use changes) the pre-industrial atmospheric CO2 is a good proxy for global SST.

2011-10-01 09:35:31
grypo

gryposaurus@gmail...
96.253.55.56

Interesting conversation.  Although we are getting away from my intended problem.  As an aside, I think the Steig incident was handled fine by Steig.  His RC posts were not inflammatory, he told it like he thought it was (as shown by his reviews later on), and the return serve was disgusting.  They pretty much tried to ruin the guy.  The reaction had been building and likely planned at the first opportunity as Neilsson-Gammon published an email he received from McIntyre asking about how to "out" a reviewer well prior to the paper's acceptance.

 

I tend to agree with Tom Curtis' on this (his version concurs with someone I trust on this), with a mix of emotions related to Mann's foolishness.  The problem is that we basically give the douche bags a pass because they're d-bags and kinda-sorta get some minor points correct, while we expect angelic behavior and perfect foreknowledge on how to deal with PR from scientists, which certainly isn't a nerd's forte.

 

But this is all besides my point.

 

I'm wondering how to fix it.  I'm wondering how to prevent these guys from stealing the narrative and framing the debate with crappy science on blogs, while damaging scientists.  We can sit here and blame Mann and Steig all we want, but we are still in the same position on the issue at the end of the day.  We know it'll happen again, and we know the result, and we know what the ramifications are of that.

 

When you invite them to submit, you end like Steig.  When you try and fight it, you end up like Mann.  I imagine they'll find a chink in Dessler and use it dishonestly.  That's just how I see it.

2011-10-01 09:52:39Comment
Robert Way

robert_way19@hotmail...
142.162.205.112

Grypo and Tom Curtis,

"The problem is that we basically give the douche bags a pass because they're d-bags and kinda-sorta get some minor points correct"

I don't think these are minor points. I think they get major points correct. MBH98 was not an example of someone using a technique with flaws and then as he learned better techniques he moved on... He fought like a dog to discredit and argue with those on the other side that his method was not flawed. And in the end he never admitted that the entire method was a mistake. Saying "I was wrong but when done right it gives close to the same answer" is no excuse. He never even said that but I'm just making a point. What happened was they used a brand new statistical technique that they made up and that there was no rationalization in the literature for using it. They got results which were against the traditional scientific communities view on the matters and instead of re-evaluating and checking whether the traditional statistics were valid (which they weren't), they went on and produced another one a year later. They then let this HS be used in every way possible (including during the Kyoto protocol lead-up that resulted in canadian parliament signing the deal with many people ascribing their final belief in climate change being assured by the HS) despite knowing the stats behind it weren't rock solid. Of course someone was going to come along and slam it. In the defense of the HS method they published things on RC like what I showed above where they clearly misrepresented the views of the foremost expert on PCA in atmospheric sciences who basically says that Mann's stats were dubious.

<> Mcl didn't actually provide a reconstruction. They were just showing the difference with a different set of rules applied. They didn't have the balls to do one themselves. Either way 2 pcs was probably too few but rationalizing the 5 that would have to be kept to get the HS shaped PC is also an interesting topic.

"As the proxies are chosen for a known, physically based covariance with temperature,"
<>  In mann 2008 the relationship with temperature in the overlapping period that was used for a cutoff was r2 > 0.1

Do you think that only having 10% of the variance in a proxy explained by temperature changes is an appropriate cutoff? I really think that's not exactly a "physically based covariance with temperature" that I would trust.

2011-10-01 11:21:29
Tom Curtis

t.r.curtis@gmail...
112.213.153.232

Robert Wray:

 MBH98 was not an example of someone using a technique with flaws and then as he learned better techniques he moved on... He fought like a dog to discredit and argue with those on the other side that his method was not flawed. And in the end he never admitted that the entire method was a mistake.

I am very far from convinced that "the entire method was a mistake".  To quote (you quoting) Tamino, "...the method is flawed, but the flaw has little or no impact on the final result."  The history of science is full of examples of important results discovered by what are later found to be flawed methods.  It is also full of examples of scientists showing too much attachment to personal ideas or techniques.  That Mann should have been hard to convince when his most open critic was misrepresenting data, presenting as superior a clearly inferior method (PCA with 2 PCs), and fairly openly insinuating fraud just shows him to be human and has no bearing on the overall issue.

 

As far as I am concerned, there are only three important questions about the Hockey Stick controversy:

1)  Did MBH have good reason to think the method was flawed before the post publication critique?

2)  Did the flaw significantly effect the result?

3)  Do climatologists still use the technique now that it is known to be flawed?

 

So far as I can tell, the answer to all three questions is no.

 

"Mcl didn't actually provide a reconstruction."

Whatever he called it, it was a reconstruction and it showed MWP level temperatures in the seventeenth century.  Note that that result is the result he claims MBH should have got with the proxies they used.  As to whether having only 2 PCs is a major flaw, the test of PC analysis is how well it reproduces the information contained in the original data.  Mann's method passes that test, while McIntyres conspicously fails.

 

""As the proxies are chosen for a known, physically based covariance with temperature,"
<>  In mann 2008 the relationship with temperature in the overlapping period that was used for a cutoff was r2 > 0.1 "

 

I'm sorry, but you appear to misunderstand the method of Mann 2008.  Mann selected proxies which where predicted for reasons of physics, chemistry, biology, or geology to covary well with temperature.  He then applied a filter designed to exclude any proxy for which the predicted covariance was falsified.  It was not the statistical analysis that predicts the covariance, but the known facts about the proxy.  A low r^2 is required for the falsification step because for all the proxies there is a significnat random component, and by chance that could dominate in the validation period in an otherwise reliable proxy.  The cut off was, of course, not decided in a vacuum, but based on the experiments conducted for "Robustness of proxy-based climate field reconstruction methods" Mann et al, 2007

http://www.meteo.psu.edu/~mann/shared/articles/MRWA-JGR07.pdf

 

I think McIntyre (and JeffID) have been very busy finding small issues that can be beaten up completely out of proportion if you are not scrupulous.

2011-10-01 12:06:53
grypo

gryposaurus@gmail...
96.253.55.56

And in the end he never admitted that the entire method was a mistake. Saying "I was wrong but when done right it gives close to the same answer" is no excuse.

This below is closer to his argument.  While it would be nice if he had come out and said the method was flawed so we can all get beyond this, the issue is more complicated

 

The claims of McIntyre and McKitrick, which hold that the “Hockey-Stick” shape of the MBH98 reconstruction is an artifact of the use of series with infilled data and the convention by which certain networks of proxy data were represented in a Principal Components Analysis (“PCA”), arereadily seen to be false , as detailed in a response by Mann and colleagues to their rejectedNature criticism demonstrating that (1) the Mann et al (1998) reconstruction is robust with respect to the elimination of any data that were infilled in the original analysis, (2) the main features of the Mann et al (1998) reconstruction are entirely insensitive to whether or not proxy data networks are represented by PCA, (3) the putative ‘correction’ by McIntyre and McKitrick, which argues for anomalous 15th century warmth (in contradiction to all other known reconstructions), is an artifact of the censoring by the authors of key proxy data in the original Mann et al (1998) dataset, and finally, (4) Unlike the original Mann et al (1998) reconstruction, the so-called ‘correction’ by McIntyre and McKitrick fails statistical verification exercises, rendering it statistically meaningless and unworthy of discussion in the legitimate scientific literature.

So did his ego get in the way?  Is this as close as we get to admittance?  It sounds like that but it also looks like he wants people to realize that the situation can't get boiled down to "I was wrong".  The method doesn't get used anymore, so I can't really see him defending this method in any scientific sense.

 

So how to we avoid this kind of thing?  Get every scientist to allow McIntyre to drive the narratives and avoid his lashing tongue?  I'd very willing to bet this is already the case.  Very unfortunate.

2011-10-01 12:11:48
nealjking

nealjking@gmail...
91.33.125.150

Having been involved in technical swordplay, I know that you have to be clear on what you must defend and what you must be ready to drop. If you make a mistake, you have to:

a) admit it quickly; and

b) isolate it's impact on the rest of the paper.

It's my impression that Mann et al. spent too much time defendinig what was incorrect, and allowed the totality of the argument to become "infected" by the fight. There is a rhythm and pace to these arguments: If you get on the wrong footing, you can be technically correct and still go down in flames.

2011-10-01 13:13:09
jyyh
Otto Lehikoinen
otanle@hotmail...
193.64.27.103

Is it this one?

http://geotest.tamu.edu/userfiles/216/dessler10b.pdf

I haven't read it yet. Could it be that Dessler used two different (reanalysis?) sets to get a larger error in the results, so the result is less robust than it could be? Is this dataset of cloud forcing? he's starting to create one of the first of its kind? This could be an initial paper on  some larger effort to use all available data to build a gridded set of historical cloud data and as such be used to f.e. disprove the 'iris hypothesis'.

Looking at table 1 on the paper there seems to be some comparisons made between observed (all-sky) vs. reanalysed (clear-sky, but I'd have to confirm that) and the same values in climate models, so I can see why McI and other extremely/excessively skeptical people are interested in finding faults on this one.

2011-10-01 15:08:46
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Grypo, Robert and Tom,

Sorry for going off topic.  I suggest people read the NRC report about MBH98.  The Wikipedia page on this is pretty good.  It is my understanding that Mann et al. were very repsonsive to the NRC report and inlcuded the report's recommendations?   Correct?

The following statement by Tom really resonated with me and if correct might explain a lot about how Mann et al. reacted to Mcintyre et al.:

"Mann was not just being criticized for using a particular technique.  His primary result was being challenged by a clearly flawed method.  Early in the controversy he was not being placed in a position where he could stop using his technique and use a better one, but being challenged for not using a worse technique."

And that is where the person who is playing games and loose with the facts and who is engaging in hyperbole and rhetoric has the advantage.  Make a lot of noise in the hopes that the scientists, who probably ultimate wants to advance the science, is intimidated enough to capitulate, even if it means adopting an (even) inferior method.  

 

Robert, re Jolliffe.  You are probably referring to this:

"Ian Jolliffe, a noted principal components authority, has posted a comment at Tamino's, which repudiates Tamino's (and Mann's) citation of Jolliffe as a supposed authority for Mannian PCA. He wrote to me separately, notifying me of the posting and authorizing me to cross-post his comment and stating that we had correctly understood and described his comments in our response here"

http://www.climateaudit.org/?p=3601"

If I recall correctly that was primarily (not exclusively) a tiff between Tamino and Jolliffe which was actually sorted out quite quickly and amicably at tamino's place. From Eli's page (unfortunately that page of Tamino's is lost):

"tgibbs said...

Anonymous writes: "Lastly, read Taminos blog and see for yourself the nasty abuse he indulges in. Finally, I see you excused yourself from replying to the innevitable gotcha.<"

I did read Tamino's blog, and found an interesting and quite polite discussion in which Tamino apologized for his misunderstanding/misstatement of Jolliffe's views, followed by an informative and courteous discussion between Tamino and Jolliffe, among others. Notably, while critical of Mann's statistical analysis, Jolliffe also comments that "my view is that the chance of all the climate models having got things completely wrong and that by 2030 the Earth is cooler than in 1950 is of the same order of magnitude as the chance that the USA will decide that independence was a bad idea and ask to be taken back as a British colony by the same date"

 

There is no denying it though, this is quite a mess and could have been dealt with much beter by some ofnt he defense, but hindsight is 20/20.  Sorry if I sounded combative today Robert, tired and stressed and not particulalry interested in rehashing this all again, so please don't take offense.

To try and get back on topic Grypo, I do not know how one controls the message.  First one can't hand them stuff that is easy to critique.  Second, one has to be proactive and anticipate bs from the like sof CA and Condon.  Really, for them it is all about being on the offensive, all the time-- which in a weird way suggests that they are on the defensive and believe that offense is the best form of defense.  But it is hard to see it that way when one is putting out fires all the time.  

McIntyre need to go down, it is quite that simple.  He was likely implicated in the Wegman plagiarism scandal.  I am pretty confident that their emails will confirm that they were conspiring and perhaps also with Barton staffers.  IMHO, the best coverage on all of this this has been by DeepClimate-- he is cool, calculating and meticulous.  I know that he intimidates McIntyre....so much so that CA try their best to pretend he does not exist ;)  DC has been quiet for a while which usually means he has been hard at work on uncovering something big......

Anyways, Dessler has to fight his own fight and I'm sure that his colleagues are helping where they can if need be. Dessler's paper clearly has them spooked and must therefore be caste into doubt at all costs. So in the meantime, expect the dog whistling and insinuations and innuendo to continue unabated at CA.  

One possibility is if the dog-whistling at CA keeps up without actually proving any problems or intent to mislead, someone ought to have a post calling them on it, but SkS wuld probably not be the best venue for that, rather DC or RC or Tamino would be better suited to deal with that.  Actually someone needs to do to CA what Ben does with WUWT-- daily documenting the BS at CA, the false accusations, the innuendo etc. etc.  I guess Willard's "Neverending Audit" comes close.

Here are some examples from McIntyre at Willard's:

"Who expects accuracy from climate scientists"

"At the time, UEA only awarded undergraduate degrees in idiocy; Acton appears to have introduced graduate degrees."


2011-10-01 15:39:39
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
97.83.150.37

Tamino's "lost" post listed above is here:

http://web.archive.org/web/20080911215131/http://tamino.wordpress.com/2008/08/10/open-thread-5-2/

 

The Joliffe interchange thus begins here:

http://web.archive.org/web/20080911215131/http://tamino.wordpress.com/2008/08/10/open-thread-5-2/#comment-21873

 


Ian Jolliffe // September 8, 2008 at 9:36 am

Apologies if this is not the correct place to make these comments. I am a complete newcomer to this largely anonymous mode of communication. I’d be grateful if my comments could be displayed wherever it is appropriate for them to appear.

It has recently come to my notice that on the following website, related to this one, my views have been misrepresented, and I would therefore like to correct any wrong impression that has been given.
http://tamino.wordpress.com/2008/03/06/pca-part-4-non-centered-hockey-sticks/

An apology from the person who wrote the page would be nice.

In reacting to Wegman’s criticism of ‘decentred’ PCA, the author says that Wegman is ‘just plain wrong’ and goes on to say ‘You shouldn’t just take my word for it, but you *should* take the word of Ian Jolliffe, one of the world’s foremost experts on PCA, author of a seminal book on the subject. He takes an interesting look at the centering issue in this presentation.’ It is flattering to be recognised as a world expert, and I’d like to think that the final sentence is true, though only ‘toy’ examples were given. However there is a strong implication that I have endorsed ‘decentred PCA’. This is ‘just plain wrong’.

The link to the presentation fails, as I changed my affiliation 18 months ago, and the website where the talk lived was closed down. The talk, although no longer very recent – it was given at 9IMSC in 2004 - is still accessible as talk 6 at http://www.secamlocal.ex.ac.uk/people/staff/itj201/RecentTalks.html
It certainly does not endorse decentred PCA. Indeed I had not understood what MBH had done until a few months ago. Furthermore, the talk is distinctly cool about anything other than the usual column-centred version of PCA. It gives situations where uncentred or doubly-centred versions might conceivably be of use, but especially for uncentred analyses, these are fairly restricted special cases. It is said that for all these different centrings ‘it’s less clear what we are optimising and how to interpret the results’.
I can’t claim to have read more than a tiny fraction of the vast amount written on the controversy surrounding decentred PCA (life is too short), but from what I’ve seen, this quote is entirely appropriate for that technique. There are an awful lot of red herrings, and a fair amount of bluster, out there in the discussion I’ve seen, but my main concern is that I don’t know how to interpret the results when such a strange centring is used? Does anyone? What are you optimising? A peculiar mixture of means and variances? An argument I’ve seen is that the standard PCA and decentred PCA are simply different ways of describing/decomposing the data, so decentring is OK. But equally, if both are OK, why be perverse and choose the technique whose results are hard to interpret? Of course, given that the data appear to be non-stationary, it’s arguable whether you should be using any type of PCA.
I am by no means a climate change denier. My strong impressive is that the evidence rests on much much more than the hockey stick. It therefore seems crazy that the MBH hockey stick has been given such prominence and that a group of influential climate scientists have doggedly defended a piece of dubious statistics. Misrepresenting the views of an independent scientist does little for their case either. It gives ammunition to those who wish to discredit climate change research more generally. It is possible that there are good reasons for decentred PCA to be the technique of choice for some types of analyses and that it has some virtues that I have so far failed to grasp, but I remain sceptical.

Ian Jolliffe

[Response: I apologize for having misrepresented your opinion, but I hope you realize that it was an honest statement of my interpretation of your presentation, in no way was it a deliberate attempt to misrepresent you.

In your presentation you state: "It seems unwise to use uncentred analysis unless the origin is meaningful." I took this to mean that you endorse uncentered analysis when the origin is meaningful. If you disagree, I accept your disagreement, but it seems to me that I can hardly be blamed for thinking so. It also seems to me (and I'm by no means the only one) that the origin in the analysis of MBH98 is meaningful.

I certainly agree with this statement from your comment: "... the evidence rests on much much more than the hockey stick. It therefore seems crazy that the MBH hockey stick has been given such prominence ..."]


-The Keeper of the Archives

2011-10-01 15:56:39Comment
Robert Way

robert_way19@hotmail...
142.162.205.112

While this is all interesting discussion I do agree with others that we are perhaps rehashing over old debates and maybe should leave things be a bit. I think the Moberg and Brattstrom (2011) paper as well as Moberg's 2008 paper discuss nicely the disadvantage of Mann and others recent work and provide the framework for "the way forward".

I do however take issue with being said that I do not understand Mann 2008's method. In the Moberg and Brattstrom (2011) paper there is discussion of the r2 cutoff issue and they use Mann's 2007 work to say that a cutoff of 0.5 or less than 0.5 can work. That being said having looked through the R code for Mann's 2008 reconstruction it does bother me that despite having proxies that "should" covary well with temperature the cutoff was as low as 0.1. 

"A low r^2 is required for the falsification step because for all the proxies there is a significnat random component, and by chance that could dominate in the validation period in an otherwise reliable proxy."

For me, if local temperature explains 10% of the variance in a proxy during the validation period then we shouldn't include it nowmatter the physical reasoning. If that random component dominates during the validation period but not in other periods than you shouldn't be using it anyways...

2011-10-01 17:26:54
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.37.112

Rob Way - you are guilty of buying too much into the skeptics framing of the situation. My point was that the science has moved on from 1998, but McIntyre hasn't. He's a one-trick pony.

I don't really care if Mann and co. made a poor statistical choice, the evidence that current warming is greater than the MCA has only accumulated in the intervening years. Obsessing over minutiae is part and parcel of science but, as climate communicators, we can't let ourselves get sucked in.

 

2011-10-01 17:28:51
Tom Curtis

t.r.curtis@gmail...
112.213.153.232

Robert, I'll leave the matter there, except to note that had Mann 2008 used a higher cutoff, you can be certain they would have been immediately accussed of cherry picking.  Based on Mann 2007, the necessity is not that each proxy have a S/N ratio greater than 0.4, but that the S/N ratio of all proxies average at least 0.4, something acheivable with some proxies having a S/N ration as low as 0.1.  Hence the low cut off.  I look forward to reading Moberg and Brattstrom.

2011-10-02 04:14:56Comment
Robert Way

robert_way19@hotmail...
142.162.205.112

RobP,

I was just making a point. My opinion has been stated on a multitude of occasions and follows the same as Ian Jolliffe's

"I am by no means a climate change denier. My strong impressive is that the evidence rests on much much more than the hockey stick. It therefore seems crazy that the MBH hockey stick has been given such prominence and that a group of influential climate scientists have doggedly defended a piece of dubious statistics. Misrepresenting the views of an independent scientist does little for their case either. It gives ammunition to those who wish to discredit climate change research more generally."