Roughly 20 years ago, climate scientist Michael Mann published his famous “hockey stick” graph that he says “galvanized climate action” by showing unprecedented global warming.
Mann used the 20-year anniversary of the graph to opine on the “industry-funded” attacks “to discredit the iconic symbol of the human impact on our climate,” which Mann claimed had withstood criticism.
“Yet, in the 20 years since the original hockey stick publication, independent studies, again and again, have overwhelmingly reaffirmed our findings, including the key conclusion: recent warming is unprecedented over at least the past millennium,” Mann wrote in Scientific American on April 20.
However, the two Canadian researchers who found serious flaws in the “hockey stick” study’s data and methodology disputed Mann’s characterization of the graph’s legacy.
“For everyone else, the debate was about data and statistical methods,” Ross McKitrick, an economics professor at the University of Guelph in Canada.
“For Mann, judging by his rant, it was all a giant political conspiracy against him and his heroic crusade to save the planet. He still won’t acknowledge the errors in his work,” said McKitrick who co-authored a 2003 study with mining executive Steven McIntyre that challenged Mann’s work.
Mann’s “hockey stick” graph, first published in 1998, was featured prominently in the U.N. 2001 climate report. The graph showed a spike in global average temperature in the 20th century after about 500 years of stability.
The “hockey stick” went viral and become a rallying cry for environmentalists and politicians who opposed fossil fuels and wanted climate policies. Former Vice President Al Gore even featured the “hockey stick” graph in his 2006 film “An Inconvenient Truth.” The graph also came under intense criticism, even sparking an investigation by GOP lawmakers.
Global warming skeptics were heavily critical of the “hockey stick” graph, especially in the wake of McKitrick’s and McIntyre’s 2003 study. Their study found serious flaws in the proxy data Mann relied upon to estimate temperatures going back hundreds of years.
The Canadians’ 2003 study showed the “hockey stick” curve “is primarily an artifact of poor data handling, obsolete data and incorrect calculation of principal components.” When the data was corrected it showed a warm period in the 15th century that exceeds the warmth of the 20th century.
Stephen McIntyre@ClimateAudit3/ in our papers, we did not take a position on modern warm period vs medieval warm period. We pointed out gross errors in Mann’s methodology, defects in the most critical proxies, and false claims about skill and robustness (what Mann called his “dirty laundry” in a CG email)
McIntyre and McKitrick also published a study on Mann’s “hockey stick” graph in 2005.
However, Mann wrote that “dozens of groups of scientists” had validated his 1998 study. Mann specifically pointed to a 2006 U.S. National Academy of Sciences (NAS) report that “affirmed our findings in an exhaustive independent review published in June 2006.”
Even McIntyre said subsequent studies have “produced somewhat hockey-stick-ish temperature reconstructions,” but added, “none (NONE) of our specific criticisms of Mann’s methods, proxies, and false claims has been rebutted.”
“The NAS report did not vindicate him, it said his methods were biased, and his results depended on faulty bristlecone pine records that shouldn’t be used by researchers,” McKitrick told The Daily Caller News Foundation by email.
“The NAS panel also cautioned against conclusions about warming more than 600 years back and said uncertainties were being underestimated,” McKitrick said. “That criticism applies to many subsequent studies as well.”
Indeed, the 2006 NAS reviewers agreed with the “substance” of Mann’s study but noted “claims for the earlier period covered by the study, from AD 900 to 1600, are less certain,” Nature.com reported at the time.
The NAS noted the uncertainties were “not communicated as clearly as they could have been” and “confirmed some problems with the statistics,” but those problems only had a minor impact on the overall finding, Nature.com reported.
However, NAS reviewers were extremely critical of the U.N. Intergovernmental Panel on Climate Change featuring the report so prominently in its 2001 assessment.
“The IPCC used it as a visual prominently in the report,” Kurt Cuffey, a NAS reviewer told Nature.com. “I think that sent a very misleading message about how resolved this part of the scientific research was.”
At the time, Mann said he was “very happy” with the NAS’s results and in the years since used his experience in defending the “hockey stick” to effectively label himself as a martyr for fighting global warming. Mann said attacks against him continued despite other researchers validating his results.
“There is no legitimate scientific debate on those points, despite the ongoing effort by some people and groups to convince the public otherwise,” Mann wrote in April as part of a screed against his critics.
Mann asks ‘What more noble cause is there than to fight to preserve our planet.’ How about the noble cause of not misleading readers with biased methods and bad data?” McKitrick said.
Read more at Daily Caller
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Ell Bee
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John O’Sullivan – In the first half of this post, you state that Dr. Mann and his lawyer, “are still pulling every trick in the book to prevent open court examination of his graph’s hidden r2 regression data.” You go on to say, “It is that ‘secret science’ element of the graph – those validation r2 regressions calculations – that can prove conclusively whether Ball’s words that Mann belongs in the “state pen, not Penn State” were an idle joke or a fair scientific appraisal.”
And then, in the second half of the article, you state,”…. McKitrick’s and McIntyre’s 2003 study. Their study found serious flaws in the proxy data Mann relied upon to estimate temperatures going back hundreds of years.”
You continue, “The Canadians’ 2003 study showed the “hockey stick” curve “is primarily an artifact of poor data handling, obsolete data and incorrect calculation of principal components.”
Does that not suggest that Dr. Mann’s data was already in the public domain since 2003? Otherwise, how could McKitrick and McIntyre do any valid critique of Mann’s work? It certainly begs the question, why was Tim Ball unable to access Dr. Mann’s data when Ross McKitrick and Steve McIntyre had been in possession of it since at least 2003? If what you say, concerning the Mann vs Ball suit and Mann’s missing r2 regression data is correct, then McKitrick and McIntyre have wasted 15 years chasing will-o’-the-wisps without it as well! However, if they were able to get it, why couldn’t Ball?
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Joseph A Olson
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“The Hockey Stick Illusion” by Andrew Montford
Three rings are useless measure of temperature. First factor in tree ring width is temperature, second is predation by diseases, insects, grazing animals and third is temperature, but temperature is a BELL CURVE, with TWO possible temperatures for any ring width other than optimum. In layman’s terms, ring widths are narrowed if it is TOO HOT OR TWO COLD.
Since precipitation and predation are not temperature dependent, and temperature has two possible values, choosing THREE TREES on the whole planet to wipe out one hundred years of LITTLE. ICE AGE RECORDS is unscientific.
“Hockey Sticker Doc” at CanadaFreePress, Feb 2010
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John O'Sullivan
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Ellbee, again you come on here spouting your ignorance. There is no conflict in the article – the conflict is in your lack of understanding. It is a matter of public record that Mann’s proxy reconstruction method was made by lining up his tree ring data with measured temperatures in the 20th century to calibrate the scale. In the process Mann used a statistic called the r-squared correlation coefficient.
Remember at school when the math teacher told you to show all your workings out? That ‘working out’ part of solving a statistical problem is the key. It reveals how you achieved your result – by fair means or foul.
We also know, from evidence in the public domain, that Mann found that over most of the reconstruction there was essentially no match (in other words the r-squared data was telling Mann his graph was junk).
We know Mann did, indeed, perform this important due diligence test because he let on that he got r-squared results for the one part of the data where there was a weak match. We also see it in the code he eventually was forced to publish.
McKitrick, McIntyre, Ball and myself all concur that Mann thereafter lied when he proudly boasted to journalists that his graph had passed the tests (it hadn’t).
He got away with that hubris for a while because he very carefully didn’t publish most of the r-squared numbers themselves. These original, unpublished r-squared numbers are what Tim Ball wants to see examined in open court and what Steve McIntyre and others have repeatedly asked Mann to release.
Instead Mann had his Penn State University employers spend upwards of a million dollars to pull every trick in the book to block open public access to his ‘workings out’ in the Virginia courts. Even Ken Cuccinelli, the Virginia AG could not prevail in getting Mann to release his hidden data. Google ‘Ken Cuccinelli Virginia versus Michael Mann (2010); or check this link: https://townhall.com/columnists/pauldriessen/2010/05/29/ken-cuccinelli-v-810-academics-n834760
Mann believed he could pull the same stunt when he sued Tim Ball in Canada.
But sadly, for Mikey different rules apply over the border. Under the vigorous and exacting ‘truth defense’ in British Columbia Ball is entitled to have open court examination of ALL Mann’s r2 regression numbers.
Mann signed an undertaking with Ball in February 2017 that in exchange for Ball giving Mann more time, in return Ball would finally get access to that data. But the crooked Mann breached that written agreement.
In fact, the r-squared numbers are what the ‘dirty laundry’ comment in the Climategate emails was about. Mann won’t release the r-squared data to Ball to pick apart in open court and would rather lose the case.
We say Mann chooses not to comply with court rules because if he did release the numbers he will be exposed for intentional fraud – a very profitable crime. McIntyre and McKitrick’s analysis shows Mann’s procedure was bad (ie it created hockey sticks whatever numbers were fed in, and Mann knew it).
In fact, statistics expert, Steve McIntyre and others have publicly demonstrated that Mann’s methods churn out ONLY hockey stick-shaped graphs whatever data is fed in. This is why every ‘scientist’ who follows Mann’s procedure also gets ‘hockey stick’ graphs. It’s ALL you get using Mann’s mendacious methodology. Mann covered up his crime to fleece millions in grants from the US federal government. He needs to spend a long time in jail.
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judy
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Mann asks ‘What more noble cause is there than to fight to preserve our planet. Independent scientists say it is more noble to save the people from extermination from Energy deprivation.COAL IS CLEAN AND RENEWABLE.. How many people have died as a result of this global scam Tim Ball is correct Mann should be in the State Penn
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