Mark Steyn has written a wonderful new book on Dr. Michael Mann’s hockey stick and the controversy surrounding it. It is difficult to overstate the significance or impact of Mann’s Hockey Stick (Mann, Bradley, Hughes (23 April 1998), “Global-scale temperature patterns and climate forcing over the past six centuries” (PDF), Nature 392 (6678): 779–787, Figure 5, the paper is often abbreviated as “MBH”). The Hockey Stick appeared in Figure 1 of the Summary for Policymakers of the third IPCC Assessment Report (called “TAR” published in 2001) and it was prominently displayed in Al Gore’s movie “An Inconvenient Truth.” As the book clearly shows, both the graph and the movie have been thoroughly discredited by hundreds of scientists who have attempted and failed to reproduce Michael Mann’s hockey stick using his data and other proxy data. Further, MBH attempts to overturn hundreds of papers that describe a world-wide Medieval Warm Period from around 900 AD to 1300 AD. The chapter devoted to Dr. Deming discusses this, for more information see here, here and here.
Professor Jonathon Jones of Oxford University:
“The hockey stick is an extraordinary claim which requires extraordinary evidence…the evidence is extraordinarily weak…its defenders were desperate to hide this fact…I’d always had an interest in pathological science, and it looked like I might have stumbled across a really good modern example…The Hockey Stick is obviously wrong. Everybody knows it is obviously wrong.”
As 1973 Nobel Prize winner Professor Ivar Giaever said “Global Warming has become a new religion – because you can’t discuss it and that is not right.”
Steyn’s book documents the problems with the hockey stick, its use by the IPCC without proper peer review or validation, and the attempt to cover up its problems. It does this artfully using the words of the scientists, both “alarmists” and “deniers” and those in between. The list of quoted scientists is huge and includes Mann’s co-authors and others who supported him even after the paper and his hockey stick were shown to be wrong and perhaps, fraudulent.
The hockey stick told us that the recent warming period (1950 to 1998) was unusual in the last thousand years and that this sort of sudden warming had (supposedly) never happened before and that man’s CO2 emissions were (presumably) the cause. After all, what else was unusual about that time period? Yet, all of these suppositions were wrong and the hockey stick was wrong. Carbon Dioxide is a greenhouse gas and it does cause warming of the atmosphere by trapping heat radiated from the ground and oceans, if everything else in the atmosphere remains equal, which it never does. The graph appeared to show that this Carbon Dioxide based warming was much more dominant in our climate than traditional paleoclimate studies, physics or chemistry would suggest. It was an extraordinary claim, yet it was accepted instantly without any validation. This had the effect of destroying the credibility of the IPCC and the previously respected publication Nature.
At the time that Michael Mann’s hockey stick was chosen to be Figure 1 of the TAR summary for policy makers, Mann had just received his PhD. As many in the book note, the ink was not yet dry on his diploma. Yet, in addition, he was made one of the lead authors of the very section of TAR that presented his hockey stick (see figure 2.20). As a result it was up to him to validate his own work. In the words of Dr. Rob Van Dorland, an IPCC lead author:
“It is strange that the climate reconstruction of Mann passed both peer review rounds of the IPCC without anyone ever really having checked it.”
The hockey stick was never validated, yet it became so famous that it was taught to young children all over the world in elementary schools. Many years later, in 2005, it was thoroughly debunked by Steve McIntyre and Ross McKitrick (often abbreviated M&M). They showed that using the statistical technique invented by Michael Mann even random number series (persistent trendless red noise, see M&M Figure 1) will generate a hockey stick. Basically, Mann had mined many series of numbers looking for hockey stick shapes and gave each series that had the shape he wanted a much higher weight, up to a weighting factor of 392! This was truly a case of selecting a desired conclusion and then molding the data to fit it. Prominent statisticians Peter Bloomfield, Dr. Edward Wegman and Professor David Hand said Michael Mann’s method of using principle components analysis was inappropriate and misleading and exaggerated the effect of recent global warming.
Mann’s notorious statistical exercise was not sufficient to build the entire hockey stick. Unfortunately for him, if his model was carried to the present day, it peaked in the 1940’s and then declined in temperature. So, he simply spliced actual estimated global temperatures to his proxy reconstruction and didn’t mention it in the article, this is the notorious and poorly understood “Mike’s Nature Trick“ scandal. More on the fraudulent parts of the hockey stick, including the Briffa “hide the decline” trick can be found here. These two links on “hide the decline” and “Mike’s nature trick” are the most balanced and informative I know of, one is by Professor Curry and the other by Steve McIntyre.
As you can see in the book many prominent scientists in the IPCC knew the hockey stick was “crap” to quote Professor Simon Tett, Chair of Earth System Dynamics, University of Edinburgh, formerly with Met Offices Hadley Climate Research Unit or CRU. And they knew it as early as 2001, but no one said anything. And, as we know from “climategate” emails, even though they knew it was “crap” they colluded to block Steve McIntyre and Ross McKitrick’s paper challenging the hockey stick. For years Dr. Michael Mann and Dr. Phil Jones (Hadley CRU) kept the supporting data for the hockey stick secret as well as the computer algorithms they used to generate the hockey stick. This very act would normally have invalidated their work and the hockey stick, but it was accepted by Nature and the IPCC anyway. A very sad period of time for science.
Dr. Kevin Vranes in 2005 said “Your [Dr. Mann’s] job is not to prevent your critics from checking your work; your job is to continue to publish…” “Why did the IPCC so quickly and uncritically accept the hockey stick?” asks Dr. Roy Spencer, “Because they wanted to believe it.” They needed it as a PR tool, they didn’t check it in any way they just ran with it.
One of the best critiques in the book is from Oxford Associate Fellow Jerome Ravetz:
“[The climate community] propounded as a proven fact, Anthropogenic Carbon-based Global Warming. There is little room for uncertainty in this thesis; it effectively needs hockey stick behavior in all indicators of global temperature, so that it is all due to industrialization. [This proposed “fact”] relied totally on a small set of deeply uncertain tree-ring data for the medieval period, to refute the historical evidence of a warming then; but it needed to discard that sort of data for recent decades, as they showed a sudden cooling from the 1960’s onwards!”
The problems encountered publishing the valid criticisms of Dr. Mann’s hockey stick are a serious indictment of the current peer review system, especially the systems at Nature and at the IPCC. Professor Hans Van Storch (University of Hamburg) went so far as to say “Scientists like Mike Mann, Phil Jones and others should no longer participate in the peer-review process.” Reform is needed and some suggestions by Professor Ross McKitrick are made here. The current peer review process can and has been used to suppress valid and important papers. This is why I applaud the internet and scientific blogs, they prevent self-serving and arrogant scientists from blocking the truth. One thing we have seen since the time of Copernicus and Galileo, no deception of this magnitude lasts forever.
Contrary to the myth that 97% of climate scientists believe we are headed toward a man-made climate doom, the truth is that a very small group of second rate climate scientists have captured the attention of some prominent political and media figures. They have also isolated themselves from the rest of the scientific community and suffer because of it. To quote Professor the Lord Oxburgh of Liverpool:
“We cannot help remarking that it is very surprising that research in an area that depends so heavily on statistical methods has not been carried out in close collaboration with professional statisticians. Indeed there would be mutual benefit if there were closer collaboration and interaction between CRU and a much wider scientific group outside the relatively small international circle of temperature specialists.”
“Given that the outputs of your work are being used to promote the largest revolution mankind has every contemplated, do you have any sense of the extent to which the quality control and rigour of approach must be of the highest standards in clear expectation of deep scrutiny?”
At this point, it is fair to ask what Dr. Mann and his colleagues have to say about all of this. The book does go there in some detail. Dr. Mann claims that his hockey stick has been replicated by others and this is true. But, they not only used the same data or similar data, but they used the same statistical techniques that have been shown to be critically flawed. One case in point is fairly typical of the others. Karoly and Gergis, in 2012, published their own hockey stick to rave reviews in the public media, especially in Australia. It claimed 95% certainty that the recent decades in Australasia were the warmest in 1000 years. They used similar proxies as Dr. Mann and used the same statistical techniques. Steven McIntyre went to work and blew it up in less than three weeks. He sent his statistical analysis to the authors. Dr. Karoly and Dr. Gergis, to their credit, recognized their error and withdrew their paper, even after the mainstream media praise. As Joanne Nova wrote, “In May it was all over the papers, in June it was shown to be badly flawed. By October, it quietly gets withdrawn.”
Just as Karoly and Gergis’s paleoclimate reconstruction disappeared, Mann’s seems to be disappearing as well. Professor Philippe De Larminat noted in 2014:
“The hockey stick curve, which ignores large climatic events, seems to have come straight from another world… This Chapter 5 [in the Fifth and latest IPCC report] in question does not make the slightest mention of the famous publication from Mann et al … neither in the text nor among the some 1,000 specific bibliographical references in this chapter. Given the extensive use that the IPCC made of it in the past (cited six times in the Third Assessment Report), and the controversy it still causes, this absence is peculiar.”
Let’s hope that hockey stick fiction goes away like the 97% consensus fiction has.
Professor Ian Plimer notes:
“In the next IPCC report, the Medieval Warming and Little Ice Age mysteriously reappeared. This suggests that the IPCC knew that the “hockey stick” was invalid. This is a withering condemnation of the IPCC. The “hockey stick” was used as the backdrop for announcements about human-induced climate change, it is still used by Al Gore, and it is still used in talks, on websites and in publications by those claiming that the world is getting warmer due to human activities. Were any of those people who view this graphic told that the data before 1421 AD was based on just one lonely alpine pine tree?”
So, the book shows that the hockey stick is dead to all scientists on all sides of the climate debate. What is the impact of this appalling chapter in the history of science? I think that Professor Judith Curry says it best:
“With regards to climate science, IMO the key issue regarding academic freedom is this: no scientist should have to fall on their sword to follow the science where they see it leading or to challenge the consensus. I’ve fallen on my dagger (not the full sword), in that my challenge to the consensus has precluded any further professional recognition and a career as a university administrator. That said, I have tenure, and am senior enough to be able retire if things genuinely were to get awful for me. I am very very worried about younger scientists, and I hear from a number of them that have these concerns.”
This is an outstanding and important book and I highly recommend it.