For those who don’t know, Ross McKitrick of the University of Guelph co-authored the first paper with Steve McIntyre debunking Michael Mann’s first Hockey Stick paper, MBH98. Ross wrote this essay in today’s Financial Post, excerpts are below. Please visit the story in that context here and patronize their advertisers. – Anthony
Flawed climate data
Only by playing with data can scientists come up with the infamous ‘hockey stick’ graph of global warming
Ross McKitrick, Financial Post
Friday, October 2, 2009
Beginning in 2003, I worked with Stephen McIntyre to replicate a famous result in paleoclimatology known as the Hockey Stick graph. Developed by a U.S. climatologist named Michael Mann, it was a statistical compilation of tree ring data supposedly proving that air temperatures had been stable for 900 years, then soared off the charts in the 20th century. Prior to the publication of the Hockey Stick, scientists had held that the medieval-era was warmer than the present, making the scale of 20th century global warming seem relatively unimportant. The dramatic revision to this view occasioned by the Hockey Stick’s publication made it the poster child of the global warming movement. It was featured prominently in a 2001 report of the U.N. Intergovernmental Panel on Climate Change (IPCC), as well as government websites and countless review reports.
Steve and I showed that the mathematics behind the Mann Hockey Stick were badly flawed, such that its shape was determined by suspect bristlecone tree ring data. Controversies quickly piled up: Two expert panels involving the U.S. National Academy of Sciences were asked to investigate, the U.S. Congress held a hearing, and the media followed the story around the world.
The expert reports upheld all of our criticisms of the Mann Hockey Stick, both of the mathematics and of its reliance on flawed bristlecone pine data.
…
Most of the proxy data does not show anything unusual about the 20th century. But two data series have reappeared over and over that do have a hockey stick shape. One was the flawed bristlecone data that the National Academy of Sciences panel said should not be used, so the studies using it can be set aside. The second was a tree ring curve from the Yamal Peninsula in Siberia, compiled by UK scientist Keith Briffa.
…
But an even more disquieting discovery soon came to light. Steve searched a paleoclimate data archive to see if there were other tree ring cores from at or near the Yamal site that could have been used to increase the sample size. He quickly found a large set of 34 up-to-date core samples, taken from living trees in Yamal by none other than Schweingruber himself!Had these been added to Briffa’s small group the 20th century would simply be flat. It would appear completely unexceptional compared to the rest of the millennium.
Combining data from different samples would not have been an unusual step. Briffa added data from another Schweingruber site to a different composite, from the Taimyr Peninsula. The additional data were gathered more than 400 km away from the primary site. And in that case the primary site had three or four times as many cores to begin with as the Yamal site. Why did he not fill out the Yamal data with the readily-available data from his own coauthor? Why did Briffa seek out additional data for the already well-represented Taimyr site and not for the inadequate Yamal site?
Thus the key ingredient in most of the studies that have been invoked to support the Hockey Stick, namely the Briffa Yamal series, depends on the influence of a woefully thin subsample of trees and the exclusion of readily-available data for the same area. Whatever is going on here, it is not science.
Read the complete story at the Financial Post
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When will the apologies start coming for the offence caused to, and vilification of, all the “so called” climate deniers? When will George Bush Jnr. be deified for holding out for so long against signing the Kyoto Accord?
Don’t hold your breath. I can’t see it happening in my life time.
Enjoy.
“And, in fact, I have previously noted that the notion of ‘proof’ is reserved for a deductive enterprise like mathematics; science is necessarily inductive and can never prove anything”
This is a myth that alarmists like to fall back on when you point out that they have the burden of proof or find flaws in their proofs. Of course it’s possible to prove things in science — just not in a mathematical sense.
For example, has it been proven that cigarette smoking causes lung cancer? Of course it has. Not mathematically, but there is overwhelming evidence which points to only one reasonable conclusion.
EricH (03:06:52) : When will the apologies start coming for the offence caused to, and vilification of, all the “so called” climate deniers?
Who do you think should apologise, to whom, for what exactly?
I have a question for all the Believers(tm) here.
McKitrick said this:
“It turns out that many of the samples were taken from dead (partially fossilized) trees and they have no particular trend. The sharp uptrend in the late 20th century came from cores of 10 living trees alive as of 1990, and five living trees alive as of 1995. Based on scientific standards, this is too small a sample on which to produce a publication-grade proxy composite. The 18th and 19th century portion of the sample, for instance, contains at least 30 trees per year. But that portion doesn’t show a warming spike. The only segment that does is the late 20th century, where the sample size collapses. ”
Are these statements true? If so, you don’t really have much to stand on.
It may very well be that Briffa did not cherry pick, he just merely took what was given to him, saw what he wanted to see, and didn’t investigate further to see if what he was seeing was representative or not.
Intentional scientific [snip], your call. Neither one is acceptable when so much is on the line…
Humm? I heard a rumor that some people think there is a symbiotic relationship between CO2 and you know, those green things that grow, plants, trees and stuff, so I would think that a 100ppm increase in CO2, (even if every other factor was identical, soil, water, sun, teperature etc), would produce greater tree ring growth, so actually I am surprised to find so few trees show a hockey stick.
The expected effect of this 100 ppm CO2 increase should be about 15% greater growth, even if temperatures stay the same!!!!
The Yamal data set being from Russia – –
Don’t I recall that Russian scientists don’t seem to hold with AGW?
Whats up with that, hey we fertilised some trees, they grew faster ( a few of them) and we said that proved warming, we got our pictures taken and more OPIM (other peoples income and money.
And wtf, hey we covinced the western world to commit economic suicide, maybe even start WWIII, but we got our grants!!!
Joel Shore says “This tangent into feedbacks, by the way, was really initiated by ” Joel, your job, at this forum and others, is to educate the rubes. To do that you can put up a link or two or a small explanation in response to one tangent that you deem to be incorrect. Otherwise, try to keep on topic else you are just diverting attention and obfuscating the main issues.
Icarus says “Clearly we can’t compare this current warming to the climate of (say) the Mediaeval period by using data that doesn’t show the current warming.” I need to repeat this, but I wish I didn’t have to. Given a population of trees in an area M, you can choose a subset N such that N is much less than M, and it is always possible to find data that shows any signal, be that current warming or anything else. That discovery doesn’t mean anything since there are always going to be trees with the right changes in local conditions (shade, terrain, ground water, competition, parasites or lack thereof, etc) combined with an unknowable amount of local temperature changes to produce the right hockey stick or any other shape.
Without seeing all the raw data and knowing the selection process, the data is unusable. It seems clear (although the realclimate crowd censors the question) that the researchers using Briffa’s data did not use the raw data. It even appears that Briffa himself did not see all the raw data or know/understand the selection process. If that is the case, he is toast. He will be the cause of a lot of rework.
Jacob T…check out this website.
http://www.climate-skeptic.com/2009/09/ocean-acidification.html
Joel Shore (17:35:42) :
Agree, and that’s all and well in the hallowed halls of academe and chummy Gordon Conferences where the wheels or research can turn at their own pace, but when there are real-world consequences and real money to be spent, and there are those that demand “immediate action”, the rules change. In my long career, I’ve seen many “peer-reviewed” studies come along that garnered headlines. Occasionaly, the claimants had the misfortune of gaining so much attention that someone was actully fool enough to think it might be of commercial value.
Peer review, schmeer review, if it don’t work, it don’t work. You can let the world of peer review and sleepy editors work for relatively unimportant stuff. If there’s real world investments necessary, thruth and quick analysis is more important than drawn out peer-review guarded by well-trained attack dogs.
Icarus (16:54:35) :
That usually happens about the time the cow becomes spherical.
“Icarus (15:57:24) :
If Steve McIntyre’s analysis fails to show the signal of recent warming that we know about from many other kinds of data, that rather suggests that he’s doing something wrong, doesn’t it? How can you draw valid conclusions from an analysis that doesn’t reflect real-world observations?
”
real world observations? or real yamal region observations? In this overwhelming plethora of posts going on about the subject my not all that great memory tells me I read a post indicating that the yamal region has not had significant temperature variations measured during the time when the briffa twelve were showing the massive hockey stick blade. If that is the case then it would seem there is even more suggestive evidence that the briffa selection was to choose trees that reflected a predetermined conclusions which was not even valid for that region. In other words, so much for selecting trees that match the relevent instrument record on the part of briffa – not that such treemometer diddling actually guarantees anything other than maybe trees grow better in atmospheres with higher co2 levels.
philincalifornia says:
Is this a serious argument that you are making? That we have nothing to worry about because whatever damage was done during the PETM, it seems to have healed by 55 million years later!?! That’s incredible!
brazil84 says:
Well, you cite a good example given that there was a long period of time between when most scientists thought this had been shown and when a few scientists and cigarette companies stopped contesting the science. Did you see the heads of the cigarette companies go before Congress back in the ’90s and say that they thought nicotine was not addictive? And, as another example, have you seen people contest evolution? In fact, our past is rife with examples of how people continue to contest scientific conclusions long after there is a consensus by most scientists in regard to them…and how they can always trot out a few scientists who hold a different opinion.
And, it probably isn’t a coincidence that some of the people associated with contesting climate change (such as Steven Milloy of JunkScience.com and also Fred Singer [ http://www.sourcewatch.org/index.php?title=Fred_Singer ] and Frederick Seitz) [ http://www.sourcewatch.org/index.php?title=Frederick_Seitz ] had associations with the tobacco companies and the questioning of the science regarding cigarette smoking (especially, although I am not sure exclusively, second-hand smoke).
Icarus (01:52:58) : is that scientists are trying to use tree ring data (amongst many other kinds of data) to establish whether 20th/21st Century warming is anomalous in the context of the last one or two millennia. Clearly we can’t compare this current warming to the climate of…
There’s the fallacy. The assumption that the current warming [in the global context] is real. The current warming (and especially the AGW component) is the hypothesis, not the established fact. Some data analysis suggests that the warming is real. Some data analysis suggests that AGW is real. Some data analysis suggests that neither is true.
All Steve McIntyre is doing is subjecting published data analysis to rigorous review, and generally, for the data analysis he is reviewing, is finding it wanting. He simply continues to test the hypothesis, and insofar as the data he tests supports the assumption, no, it neither supports the assumption, nor the hypothesis. Simple, really.
http://www.spectator.co.uk/melaniephillips/5389461/the-great-global-warming-scam-ctd.thtml
Kurt says:
The NAS report weighs in on this point specifically ( http://books.nap.edu/openbook.php?record_id=11676&page=113 ):
jorgekafkazar says:
It just happens to be the facts of this case. And, I find it interesting that you are so sensitive to what you consider ad hominem attacks but have failed to notice that ad hominem attacks are completely central to the entire “skeptic” case. After all, how else are you going to argue against the fact the IPCC conclusions and the fact that practically ever major scientific organization on the planet that has weighed in on the issue of climate change has supported the IPCC conclusions? In fact, we are told that the entire climate science community can’t be trusted because they are corrupted by grants or what-have-you.
Trying to measure temperature with tree rings is like trying to measure your height by standing on the bathroom scales.
will says:
I hope you were citing that as an example of how desperately pathetic some of the arguments are to dismiss the concerns regarding CO2! Please tell me that this was your motivation! (The first two comments in response to that post are, by the way, dead on.)
“how else are you going to argue against the fact the IPCC conclusions ”
Very easily . . . by looking critically at the actual evidence and arguments on each side.
“hominem attacks are completely central to the entire ‘skeptic’ case.”
Nonsense. The skeptical case rests on actual evidence and arguments. (More precisely, a lack of evidence and solid, valid argument from the warmist side.)
By the way Joel Shore’s attitude reflects a typical warmist bias, in my opinion. When I have debated with warmists, they have constantly attempted to shift the discussion into a debate over who is authoritative, as opposed to a debate over the actual science.
To me, this bias itself is a red flag. Imagine you were trying to convince somebody that perpetual motion machines are impossible. Or that cigarette smoking causes lung cancer. Or that psychic phenomenon don’t exist. Or that the moon trip actually took place. In each case, the LAST argument you would make is the consensus argument — if you made it at all. Because in each case, there are solid arguments and/or evidence supporting your position on the merits. It’s not necessary to fall back on arguments from authority.
“After all, how else are you going to argue against the fact the IPCC conclusions and the fact that practically ever major scientific organization on the planet that has weighed in on the issue of climate change has supported the IPCC conclusions?”
This is the logical fallacy Appeal to Authority. Acronyms and social status do not insure correctness about an issue.
Andrew
Joel, since you an expert at maintaining tangential conversations, how about going back to RC where you are a contributor and ask them why they allow such tangential red herring rubbish through (to paint all skeptics as talking point readers) and not answer 303 with an explanation of how many other hockey players (use a more PC term) used Briffa’s data without examining his (just-released) raw data. Otherwise try to stay on topic here.
Obviously AGW-co-creators can keep their hypothesis in play based on technicalities.
Those whose minds are not carrying the hypothesis can step back and allow simpler broad generalities, seen in context, to be apprehended.
That was what happened with Wegman, where they were expertly reviewing the technicalities of what could and could not be said. AGWers clutched to the technicalities like a man clutching at straws, whilst everyone else noted that broadly speaking, the hockeystick didn’t tell us much of anything at all in practical terms.
Technically the other papers are independent, but in practice they are not. Technically the trees can be a proxy for temperature, but in practice, the samples used and the assumptions used are too finicky to be trusted. Technically, there is one line forming the graph, but in practice, the line is an illusion generated from unprecedented and idiosyncratic procedures, more akin to a person’s own signature than an obvious natural fact.
Joel Shore (19:38:15) states that “the Wegman panel was convened by the Republican majority who chose Wegman and the narrow charge that they gave the panel in order to get the answer that they wanted. ”
Is Mr. Shore claiming that Wegman and his panel participated in some kind of fraud? The statement above sure seems to denigrate the work of a truely outstanding scientist. Otherwise, why would Mr. Shore tarnish Mr. Wegman’s report by claiming he was chosen by a “Republican” majority?
brazil84: I’ve spent a lot of time discussing the science, but as the examples of cigarette smoking and evolution demonstrate, one is not going to be able to convince people on the basis of the science if they are sufficiently motived by their own biases not to believe it.
As for “appeals to authority”, while such appeals may not logically prove something to be true, it is generally true that scientific authorities are trusted more than just the “Average Joe” on scientific issues for very good reason. And, this is why “skeptics” tend to come up with grand theories to explain why all the scientific authorities are aligned against them.
No. Read what I said in context. They were chosen by the Republican majority to deal only with a narrow issue that most everyone now agrees with, namely, that the method used in the original Mann et al. work does have certain real problems that mean that it is not the recommended method. And, like I’ve said, it is hardly the first case where the pioneering work in a field used some methods that were later found to be problematic in some ways and superceded by better methods.
That being said, I think that Wegman showed poor judgment in going beyond his competency to address issues where he really did not have the background. (E.g., a year or so after he wrote his report, he signed onto a letter to policymakers disputing the basic science of AGW even though he showed himself to really not have the necessary background to evaluate any more than a tiny fraction of this science).