This is the legal brief our counsel filed today in the DC Court of Appeals in the lawsuit filed against NR by Professor Michael Mann.
As many of our donors have helped support our legal efforts, I thought you might wish to see our brief and be updated on the case.
Jack Fowler [Publisher of National Review]
Public criticism of the hockey stick
Since its initial publication, the hockey stick has been at the center of a firestorm of controversy and criticism. Two of the most prominent critics have been University of Guelph professor Ross McKitrick and retired mining engineer Stephen McIntyre, who published two peer-reviewed articles in scientific journals arguing that the hockey stick is spurious in both its methods and its conclusions. Other critics include academics such as Richard Lindzen, a distinguished professor in the Department of Earth, Atmospheric and Planetary Sciences at the Massachusetts Institute of Technology (MIT); Judith Curry, the former chair of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology; and John Christy, a climate scientist at the University of Alabama in Huntsville. Numerous books have been written criticizing the hockey-stick hypothesis, including most notably The Hockey Stick Illusion: Climategate and the Corruption of Science (2010), by A.W. Montford, and Taken By Storm: The Troubled Science, Policy and Politics of Global Warming (2002), by Ross McKitrick and Christopher Essex. In addition to the scientific criticism, the hockey stick remains deeply controversial in political circles. To take but one example, United States Senator James Inhofe has written a book entitled, The Greatest Hoax: How the Global Warming Conspiracy Threatens Your Future (2012). As described in the book’s promotional summary, the thesis is that “the entire global warming, climate-change issue . . . is an effort to dramatically and hugely increase regulation of each of our lives and business, and to raise our cost of living and taxes.”4
Critics of the hockey-stick graph have focused on what they believe to be four serious flaws in its underlying methodology. First, they have questioned the reliability of the graph’s underlying data. Because there are no thermometer records before the middle of the 19th century, the bulk of the hockey stick is composed of so-called “proxy” data, such as ancient tree rings, sedimentary pollen levels, and oxygen isotopes frozen in polar ice caps. Dr. Mann argues that these proxy data can be interpreted to provide an accurate record of global temperatures going back more than a thousand years. Some critics disagree. They argue, for example, that tree-ring formations cannot provide an accurate measure of global historical temperature trends—in part because temperatures fluctuate unevenly in different parts of the world, and in part because the relevant tree-ring characteristics are influenced not only by temperature changes but also by variable growth factors such as sunlight, water, and soil nutrients. In the eyes of critics, any statistical model that uses such data to reconstruct centuries of historical temperature trends is fundamentally flawed and misleading.
Second, critics have argued that the hockey stick relies on flawed statistical techniques, including a skewed Principal Components Analysis (“PCA”), producing an erroneous and misleading interpretation of the underlying data. For example, according to Professor David Hand, the former President of the Royal Statistical Society in Great Britain, “The particular technique [used by Dr. Mann and his co-authors] exaggerated the size of the blade at the end of the hockey stick. Had they used an appropriate technique the size of the blade of the hockey stick would have been smaller.”5 If one uses a better statistical method, “[t]he change in temperature is not as great over the 20th century compared to the past as suggested by the Mann paper.” Id.
Third, critics have argued that the hockey stick is misleading because it splices together two different types of data without highlighting the change: For roughly the first nine centuries after the year 1000 A.D., the graph shows temperature levels that have been inferred solely from tree-ring samples and other “proxy” data. But from about 1900 onward, the graph relies on readings from modern instruments such as thermometers. In the words of one review conducted by a panel of independent scientists, many consider it “regrettable” that temperature reconstructions “by the IPCC and others” neglected to emphasize “the discrepancy between instrumental and tree-based proxy reconstructions of temperature during the late 20th century.” J.A. 370.
Fourth, critics have contended that the hockey stick is misleading because it omits certain tree-ring data after the year 1960 that show a decline in global temperatures, and instead relies more heavily on thermometer readings that show an increase in temperatures during that period. The omission of these data gained widespread public attention after the leak of multiple e-mails from the University of East Anglia’s Climate Research Unit (“CRU”), prompting an uproar popularly known as “Climategate.” In one particularly controversial e-mail, CRU scientist Phil Jones wrote to Dr. Mann and two other scientists: “I’ve just completed Mike’s [i.e., Dr. Mann’s] Nature trick of adding in the real temps to each series for the last 20 years (i.e. from 1981 onwards) [and] from 1961 for Keith’s to hide the decline.”6 Dr. Mann himself has not denied the omission of certain proxy data after the year 1960, but has argued that the omission is legitimate: “[T]hese data should not be used to represent temperatures after 1960,” he explains, because “the density of wood exhibits an enigmatic decline in response to temperature after about 1960.”7 In other words, because temperature measurements from modern instruments show that these data points are not reliable, Mann contends that it is legitimate “not to show those data during the unreliable post-1960 period.” Id. Critics disagree, arguing that the hockey stick should have included the post-1960 proxy data to give a more full and accurate picture: since modern instruments have shown tree-ring proxies to be inaccurate after 1960, they say, this also calls into question the reliability of the proxy data from earlier years, where no thermometer readings are available to provide an independent check.
Based on these four separate criticisms, Dr. Mann and his detractors have engaged in a long-running public debate over the validity of the hockey stick and its underlying methodology. Dr. Mann and his defenders characterize the hockey stick as methodologically sound, contending that it gives an accurate picture of the dire threat global warming poses. Critics of the hockey stick characterize it as badly flawed, contending that its reliance on questionable statistical techniques and its method of data presentation render it false and misleading. In testimony before the United States Congress, Professor John Christy summarized the critical view by stating that “evidence now indicates . . . that an IPCC Lead Author working with a small cohort of scientists, misrepresented the temperature record of the past 1000 years by (a) promoting his own result as the best estimate, (b) neglecting studies that contradicted his, and (c) amputating another’s result so as to eliminate conflicting data and limit any serious attempt to expose the real uncertainties of these data.”8...
"For something to be considered libel, it must involve false statements knowingly presented as fact. In the United States, opinion is protected as a tenant of freedom of speech, and citizens retain the right to comment on public figures and entities, including government and officials. Entertainment, parody, editorials, and criticisms that may arguably misrepresent facts are not libelous so long as they are presented for amusement or stated as mere opinion. Public figures [like Mann] must also meet a higher standard for proving libel than private citizens. Private citizens need only prove negligence, while public figures must show malice."
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There He Goes Again, Version 5.0: Mann Claims His Hockey Stick was Affirmed by the NAS