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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“Jacob T (08:56:16) :
Jacob, not to worry. There are adequate basaltic rocks rich in calcium and magnesium being weathered on land and errupting on the ocean floor (Hawaii and iceland etc) to buffer the carbolic acid from CO2 absorbed by the worlds oceans. This results in the formation of limestone and dolomite. I live on the Pacific Ocean and the clams and oysters on my beach are doing just fine (inspite of urban runoff!!! ) Sigourney Weaver may be an excellent actress but she mainly deals in fiction.
“Daryl M (11:34:38) :
Gordon Ford (08:20:51) :
PS – If the ruth were known Canadian Conservatives are probably to the left of American Democrats!
Gordon, as a “Canadian Conservative”, I take great exception to that remark. True there are some Canadian policies that are considered “left wing” by Americans, that does not place Canadian Conservatives to the left of American Democrats. America has its share of hard left wingers (i.e., ACORN).
Doug in Seattle (09:34:57) :
Gordon Ford (08:20:51) :
PS – If the (t)ruth were known Canadian Conservatives are probably to the left of American Democrats!
As someone who has lived in both countries I can confirm your hypothesis.
For instance you will not find many Canadians, even true blue Conservative, who want to revert to a private heath care system.
On the other hand Steve McIntyre at CA has made it a point over the years to remind his more conservative readers that he is fact a liberal.
This latter fact is unknown to most AGW supporters (and foes too) here in the US.
While I usually chuckle when I read some troll drool that links McIntyre with the far right, this attribution of skepticism to the right is way off base. I know of several people personally who are “red banner” lefties that don’t buy the AGW line but support it for political reasons. I even know a few who are vocally skeptical and don’t support it.”
Daryl, Doug:
Personnaly, my politics are to the right of Atilla the Hun. However I carefully evaluate the arguments of left wingers like McIntyre, and if logical accept them. I realize that us politically correct right wingers are not always correct when it comes to science.
Trapper
“I think that would contradict what we know about biology – no-one actually disputes that trees will *tend* to grow more when there is warmer weather and a longer growing season,”
I dispute it. Well, actually I am skeptical. Perhaps warmer weather helps trees to grow more densely, resulting in larger numbers of trees with thinner rings. Perhaps warmer weather encourages the spread of parasites which are injurious to trees. Perhaps warmer weather is better for young trees than old trees. Or vice versa.
“all other things being equal.”
When studying a complex system, it’s dangerous to assume that all other things are equal. Because there is interplay between and among different variables.
“A careful and thoughtful analysis of tree ring data would have to include ways of isolating the effects of climate change from other influences… agreed? ”
I don’t agree. A careful and thoughtful analysis might simply conclude that somebody else’s analysis is flawed.
Jacob T (08:56:16) :
Don’t worry a bit. The buffering capacity of the ocean is enormous, and to my knowledge there is no evidence that the ocean was heavily acidified 100-300 million years ago, when the atmospheric CO2 concentration was most probably 2000-3000 ppm, namely 5 to 8-fold higher than today.
tokyoboy says:
The way the buffering works is that CaCO3 (limestone) rocks dissolve and go into the oceans to restore the pH. However, the problem is not the atmospheric level of CO2 but the current rate of increase, which is overwhelming the rate at which the CaCO3 dissolved from the rocks can perform this process.
And, by the way, as I understand it, it is not in fact true that there is no evidence of acidification in the past. It is believed to have occurred during the PETM climate event 55 million years ago.
Icarus says:
“A careful and thoughtful analysis of tree ring data would have to include ways of isolating the effects of climate change from other influences… agreed? If McIntyre’s analysis isn’t able to do this, perhaps this suggests it is not a useful contribution to the science.”
Steve M. has been repeating your first statement for years, so there is no disagreement there. But your second statement implies that Steve M should travel to Yamal to inspect each of the 10 trees. It’s a lot simpler than that. If there are a million trees to choose from, there will be 10 that match anything, whether that is an instrument record, precipitation, CO2, the stock market or any other series you want. That is a statistical fact. The only question is how the 10 were selected. The Russians picked them seems to be the favorite answer right now.
Without even knowing how they were selected (and it does not appear to be random), there is a huge sample size problem using just 10 trees. It crosses the line into poor practices when there are other trees in the same area that were left out. Without seeing the 10 tree raw data, all subsequent use of Yamal cooked data is highly questionable. There was an implicit trust in that use and that trust has been broken.
marnot:
I’m not sure who those people are. I don’t see anyone arguing that his representation of the Wegman panel is misleading. However, 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. (The panel was asked just to answer some technical questions regarding the statistical method applied and not to look at the larger issues such as whether the problems with the method had any affect on the result. In fact, the panel didn’t really have the expertise to go beyond the narrow statistical issues since Wegman and those he chose to work with him knew essentially zilch about climate science in general or proxy temperature reconstructions in particular. )
The NAS panel, by comparison, was given a broader charge…and was actually run in the non-partisan way that the NAS is geared toward.
Joel Shore: that’s an interesting tangent into models and water vapor feedback (the sciencemag article). Reminds me of similar tangents on other forums. But the article is vastly oversimplified. Their article doesn’t talk about the primary problem which is that models are too coarse to adequately model WV feedback since it is largely a highly nonlinear function of meso-scale convection.
Joel Shore: thanks for clarifying the AGW mantra: “the procedure may be invalid but the results aren’t really affected”. Proxies abound for the MWP that point to a period, with variations, that was similar or warmer overall than today. One is sea level which was the same or higher. Another is glaciation that had receded in amounts similar to today (on a worldwide basis). Another is seasonal changes that people like you like to point to. They were accurately measured in the MWP as siimilar or warmer than today (most of those measurements were made in Europe).
People can know “zilch” about tree ring shenanigans and still come to the right conclusion with much simpler evidence. That conclusion is that today’s warming has MWP (and many more) precedents.
Joel Shore, The actual Wegman report is readily available online, enough of your mis-quotes and confusion.
Word for word from the Wegman report:
The debate over Dr. Mann’s principal components methodology has been going on for nearly three years. When we got involved, there was no evidence that a single issue was resolved or even nearing resolution. Dr. Mann’s RealClimate.org website said that all of the Mr. McIntyre and Dr. McKitrick claims had been ‘discredited’. UCAR had issued a news release saying that all their claims were ‘unfounded’. Mr. McIntyre replied on the ClimateAudit.org website. The climate science community seemed unable to either refute McIntyre’s claims or accept them. The situation was ripe for a third-party review of the types that we and Dr. North’s NRC panel have done.
While the work of Michael Mann and colleagues presents what appears to be compelling evidence of global temperature change, the criticisms of McIntyre and McKitrick, as well as those of other authors mentioned are indeed valid.
Where we have commonality, I believe our report and the [NAS] panel essentially agree. We believe that our discussion together with the discussion from the NRC report should take the ‘centering’ issue off the table. [Mann’s] decentred methodology is simply incorrect mathematics …. I am baffled by the claim that the incorrect method doesn’t matter because the answer is correct anyway.
Method Wrong + Answer Correct = Bad Science.
The papers of Mann et al. in themselves are written in a confusing manner, making it difficult for the reader to discern the actual methodology and what uncertainty is actually associated with these reconstructions.
It is not clear that Dr. Mann and his associates even realized that their methodology was faulty at the time of writing the [Mann] paper.
We found MBH98 and MBH99 to be somewhat obscure and incomplete, and the criticisms of MM03/05a/05b to be valid and compelling.
Overall, our committee believes that Mann’s assessments that the decade of the 1990s was the hottest decade of the millennium and that 1998 was the hottest year of the millennium cannot be supported by his analysis.
[The] fact that their paper fit some policy agendas has greatly enhanced their paper’s visibility… The ‘hockey stick’ reconstruction of temperature graphic dramatically illustrated the global warming issue and was adopted by the IPCC and many governments as the poster graphic. The graphics’ prominence together with the fact that it is based on incorrect use of [principal components analysis] puts Dr. Mann and his co-authors in a difficult face-saving position.
We have been to Michael Mann’s University of Virginia website and downloaded the materials there. Unfortunately, we did not find adequate material to reproduce the MBH98 materials. We have been able to reproduce the results of McIntyre and McKitrick
Generally speaking, the paleoclimatology community has not recognized the validity of the [McIntyre and McKitrick] papers and has tended to dismiss their results as being developed by biased amateurs. The paleoclimatology community seems to be tightly coupled as indicated by our social network analysis, has rallied around the [Mann] position, and has issued an extensive series of alternative assessments, most of which appear to support the conclusions of MBH98/99… Our findings from this analysis suggest that authors in the area of paleoclimate studies are closely connected and thus ‘independent studies’ may not be as independent as they might appear on the surface.
It is important to note the isolation of the paleoclimate community; even though they rely heavily on statistical methods, they do not seem to be interacting with the statistical community. Additionally, we judge that the sharing of research materials, data and results was haphazardly and grudgingly done. In this case we judge that there was too much reliance on peer review, which was not necessarily independent.
Based on the literature we have reviewed, there is no overarching consensus on [Mann’s work]. As analyzed in our social network, there is a tightly knit group of individuals who passionately believe in their thesis. However, our perception is that this group has a self-reinforcing feedback mechanism and, moreover, the work has been sufficiently politicized that they can hardly reassess their public positions without losing credibility.
It is clear that many of the proxies are re-used in most of the papers. It is not surprising that the papers would obtain similar results and so cannot really claim to be independent verifications.
Especially when massive amounts of public monies and human lives are at stake, academic work should have a more intense level of scrutiny and review. It is especially the case that authors of policy-related documents like the IPCC report, Climate Change 2001: The Scientific Basis, should not be the same people as those that constructed the academic papers.
Joel Shore (19:27:12) :
And, by the way, as I understand it, it is not in fact true that there is no evidence of acidification in the past. It is believed to have occurred during the PETM climate event 55 million years ago.
____________________________________
So, do us all a favor Joel, and go on to all the “corals are going to die” websites and educate them on the errors in their thinking …
…. please.
Jerry Haney says:
What misquotes are you talking about? You guys seem to prefer making up your own strawman arguments to respond to rather than responding to the actual arguments that I make.
Eric (skeptic) says:
I don’t understand what you are saying. They admit that the way that the models handle the transport of water vapor are pretty simplistic but the point is that the empirical data supports the results that they produce:
(This tangent into feedbacks, by the way, was really initiated by Jordan, not me.)
philincalifornia says:
I don’t understand…Do you think that catastrophic events that have caused harm to various lifeforms have never happened in the past? Here is the full quote about the PETM event (from “The Long Thaw” by David Archer, p. 116):
Joel Shore (17:51:27) : “…And, it is hard to argue against the ice-albedo feedback being positive…”
Not really. Some types of polar ice have poor reflectance, particularly when dirty or weathered. The albedo of seawater at high zenith angles, such as apply at the poles, overlaps the albedo of ice. Have you ever driven down to the ocean in the afternoon and seen the sun reflecting off the water so brightly you couldn’t look at it? That’s at a relatively low zenith angle. At polar latitudes, the reflectance of sea water is even greater. Also, the emissivity of sea water is about 0.993, considerably greater than ice. Thus polar sea water gets rid of heat faster than ice does (especially when you factor in the insulation coefficient for ice) and absorbs heat just about the same as ice. The feedback may actually be slightly negative over an annual cycle. There will always be ice at the poles in winter.
Some people are introducing a red herring in this debate by claiming that McIntyre has to prove this or that, or by focusing on Briffa’s intentions .
McIntyre simply provided a mathematical invalidation of Briffa’s hypothesis, he does NOT need to prove anything.
It is up to the proponent of the hypothesis to overcome the scientific objections. In his response, Briffa has acknowledged some “valid points” made by McIntyre.
As it stands now, the hypothesis has been invalidated pending Briffa’s scientific response, which must overcome the objections raised.
Good Luck Briffa!
Joel Shore (19:38:15) : “…the Wegman panel was convened by the Republican majority…”
Ad hominem. Ad ho-hum.
philincalifornia:
Here is an article from a few years ago on the PETM event: http://www.sciencemag.org/cgi/content/abstract/308/5728/1611
This paper and the list of papers that have cited it should provide you with plenty of reading about what is understood about the PETM event, its causes, and its consequences.
“Joel Shore (19:38:15) :
[T]he 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. (The panel was asked just to answer some technical questions regarding the statistical method applied and not to look at the larger issues such as whether the problems with the method had any affect on the result. In fact, the panel didn’t really have the expertise to go beyond the narrow statistical issues since Wegman and those he chose to work with him knew essentially zilch about climate science in general or proxy temperature reconstructions in particular. )”
This is an odd way of chartacterizing the issue. In that particular instance, the climate scientists were applying a complex statistical procedure to a set of data. The study at issue was essentially nothing more than applied mathematics, and when the Wegman panel (the statistical experts) evaluated the study, their conclusion was that the climate scientists didn’t know what they were doing. The NAS panel agreed with that assessment.
Determining whether the Mann paper used proper methodology is not a “narrow statistical issue.” It was the only relevant issue. Nor is there some distinct question of whether the flawed statistics affected the result, because the Wegman panel demonstrated that the result of the Mann paper was purely a function of the flawed statistics, i.e. the hockey stick shape was baked into the procedure and would result even from random data thrown into the methodology. Separating the result from the methodology that produced the result is nonsensical.
I would argue that the Wegman panel demonstrated that the climate scientists “knew zilch” about the mathematical procedure by which they were analyzing data. That’s a pretty damning assessment given that climate science is almost pure theory. When you get right down to it, the whole of the quantitative aspect of climate science, at least, rests on nothing more than an application of statistics, whether you are trying to infer past climate through temperature reconstructions or whether you are trying to validate mathematical models of climate. When, not only the authors of the Mann paper are shown to be clueless as to the statistical methods they were applying, but also when the IPCC along with every other climate scientist on the global warming bandwagon was defending the Mann methodology right up to the poinit when the IPCC and Wegman told them they were wrong and that McIntyre right, it doesn’t engender a lot of confidence in the climate scientists expertise when they fall back on the excuse that their collective ineptitude doesn’t matter because the result, they somehow divine, happens to be right anyway.
Joel Shore (20:26:04) :
philincalifornia:
Here is an article from a few years ago on the PETM event: http://www.sciencemag.org/cgi/content/abstract/308/5728/1611
This paper and the list of papers that have cited it should provide you with plenty of reading about what is understood about the PETM event, its causes, and its consequences.
__________
Fantastic Joel, and the corals made it through all that, and we can still see them and touch them ….
… but, after millions of years of this, they’re gonna die any second now !!!!
What happened on the Briffa debate – you get ill or something ??
Joel Shore (20:18:18) :
philincalifornia says:
So, do us all a favor Joel, and go on to all the “corals are going to die” websites and educate them on the errors in their thinking …
…. please.
I don’t understand…Do you think that catastrophic events that have caused harm to various lifeforms have never happened in the past? Here is the full quote about the PETM event (from “The Long Thaw” by David Archer, p. 116):
Carbon secreters were singled out for extinction in response to the acidification of the ocean during the PETM climate event 55 million years ago (Chapter 6).
_________________
…. which explains, to some extent, possibly, why we would have the corals we have now, some of those being more acid (or more technically), less alkaline-resistant.
So, go on, educate those less pompous masses about things that happened before 1950. I promise I will help with their education.
“I have been probing the arguments for global warming for well over a decade. In collaboration with a lot of excellent coauthors I have consistently found that when the layers get peeled back, what lies at the core is either flawed, misleading or simply non-existent. “
“The surface temperature data is a contaminated mess with a significant warm bias, and as I have detailed elsewhere the IPCC fabricated evidence in its 2007 report to cover up the problem.”
“Climate models are in gross disagreement with observations, and the discrepancy is growing with each passing year. “
“The often-hyped claim that the modern climate has departed from natural variability depended on flawed statistical methods and low-quality data.”
“The IPCC review process, of which I was a member last time, is nothing at all like what the public has been told: Conflicts of interest are endemic, critical evidence is systematically ignored and there are no effective checks and balances against bias or distortion.”
All salient points. McKitrick is worth quoting again and again.
Science is about the pursuit of truth. My how far we have come and “devolved” in the current AGW religious cult group-think.
Perhaps the future will be better.
Chris
Norfolk, VA, USA
Kurt,
Thanks for setting the record straight on the Wegman panel. Having read the entire story I was well aware of the omissions by others.
The shame of the story is that it took an “act of Congress” to get the facts on the table. As I recall the NAS were less than forthcoming on the issue until they were put under oath and forced to answer direct questions.
Unfortunately, This gives an insight into the integrity of those we are dealing with.
enduser (12:51:58) :
http://www.washingtonpost.com/wp-dyn/content/article/2009/09/30/AR2009093003569.html?sub=AR
________________________
Indiana, did you check out the comments on Mr. Will’s article? The unwashed Warmie masses are having a fit of apoplexy over it.
Yes, I’ve read some comments. Standard apoplexy. Defenders of cultist practice react this way – militant righteousness consumed with devotion. The appearance of a mainstream skeptic frustrates their scorched earth policies.
George however, is right. There should be a national review of climate evidence populated by qualified experts on both sides. But before that happens the Briffa “Hot Tree” episode may result in some long needed adjustments. The magnitude of the Hot Tree scandal is rapidly dwarfing Earth’s previous great science hoax: Piltdown Man.
Eric (skeptic) (19:35:17) : Icarus says:
“A careful and thoughtful analysis of tree ring data would have to include ways of isolating the effects of climate change from other influences… agreed? If McIntyre’s analysis isn’t able to do this, perhaps this suggests it is not a useful contribution to the science.”
Steve M. has been repeating your first statement for years, so there is no disagreement there. But your second statement implies that Steve M should travel to Yamal to inspect each of the 10 trees.
Well, no. The whole point of this issue, as many others have discussed here, 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 (say) the Mediaeval period by using data that doesn’t show the current warming. This pretty much goes without saying. McIntyre’s analysis, unlike Briffa’s, doesn’t seem to show the current warming, so it can’t tell us anything about the issue at hand – i.e. whether or not current warming is anomalous. I don’t know whether that is a problem with the data he’s using, or his methods, but that question is really beside the point. If McIntyre’s analysis can’t be used to tell us anything about the climate then it’s of no value to the science.
Agreed?
Scott A. Mandia (14:40:27) :
Go on, do comment on Bishop Hill. Your struggles will be good for a guffaw or two.