Monday, December 5, 2011

There He Goes Again, Version 5.0: Mann Claims His Hockey Stick was Affirmed by the NAS

In a letter to the editor published today in the Wall Street Journal, climate fraudster Michael Mann continues to falsely claim the National Academy of Sciences affirmed his hockey stick, insists there is 'overwhelming evidence' supporting the climate hoax [what specifically?], and again makes the ridiculous straw man argument that climate realists are fossil-fuel industry shills using political tactics of the tobacco and lead industries.

"Climate Contrarians Ignore Overwhelming Evidence"

Every snowflake is unique, but attacks on climate science all seem the same. I should know. I've been one of the climate contrarians' preferred targets for years.

A recent op-ed on this page by blogger and climate-change denier James Delingpole attacked the "hockey stick" graph my co-authors and I published more than a decade ago with well-worn, discredited arguments ("Climategate 2.0," Nov. 28).

Our original work showed that average temperatures today are higher than they have been for at least the past 1,000 years. Since then, dozens of analyses from other scientists based on different data and methods have all affirmed and extended our original findings.

Contrarians have nonetheless painted a misleading picture of climate science as a house of cards teetering on the edge of a hockey stick. In reality, my research is just one piece in a vast puzzle scientists have painstakingly assembled over the past 200 years establishing the reality of human-caused climate change.

Does that mean that everyone should have to drive an electric car and adopt a polar bear? Of course not. Policy decisions must balance matters of economics, international diplomacy and ethics in a way that is informed, rather than prescribed, by science.

In 2006, then-Rep. Sherwood Boehlert (R., N.Y.) asked the National Academy of Sciences to look into studies like the hockey stick. It affirmed our conclusions.

In recent years, attacks on climate science have become personal. After my colleagues and I had our emails stolen and posted online in November 2009, attacks from climate contrarians were subsequently shot down by investigations from two universities, the National Science Foundation, two federal agencies and several media outlets. Contrarians declared that those institutions were part of an imagined global-warming conspiracy.

In April 2010, Virginia Attorney General Ken Cuccinelli demanded emails I sent or received from other scientists while at the University of Virginia. A judge concluded Mr. Cuccinelli hadn't demonstrated any good reason to see that correspondence. Shortly after that, the American Tradition Institute, a group with ties to fossil-fuel interests, asked for the same emails under the state's open records laws. The university rightly asserted that much of my private correspondence is just that and not subject to release.

Many fossil-fuel interests and their allies are following the same attack-the-science strategy that tobacco companies adopted to delay smoking regulation. Climate scientists can also find kinship with Dr. Herbert Needleman, who identified a link between lead contamination and impaired childhood brain development in the 1970s. The lead industry accused him of misconduct. Later, the National Institutes of Health exonerated him.

Mr. Delingpole ends his piece by saying the anonymous hacker or hackers who stole emails from me and my colleagues deserve thanks. What they deserve is to be brought to justice. But British police have not determined who stole the emails. Recent reports of police expenditures suggest they may be devoting far fewer resources to it than other similar investigations.

Celebrating theft is silly. We should respect the role science and scientists play in society, especially when scientists identify new risks. Whether those risks stem from smoking, lead exposure or the increasing use of fossil fuels, scientists will always work to increase knowledge and reduce uncertainty. And we all benefit from that work.

Prof. Michael E. Mann
Meteorology Department
Penn State University
Director, Penn State Earth System Science Center
University Park, Pa.


  1. Mann's hockey stick may have been approved by whoever, but it has not been approved by planet earth, because the tempersture is nowhere going to what Mann had predicted. It's just a sham, produced by a scammer, paid by our taxes who now refuses to show his arithmetic.

  2. Aren't you the same guys who criticised Phil Jones for saying that 13 years was too short a time (statistically speaking) to say it had warmed? Now you want us to use the same time period to say it hasn't warmed and you do this by starting with the biggest El Nino year on record (1998) and finishing with a 16-month period where the data points have only been 10% plotted. Will you print a retraction when more data points become available ant the graph ends with an upward spike?

  3. Oh please
    1. I never "criticised Phil Jones for saying that 13 years was too short a time (statistically speaking) to say it had warmed"
    2. I don't claim statistical significance anywhere
    3. The data points are not "10% plotted"
    4. The graph is updated in Feb of each year and the trend line at that time will be shown




    Morgan Mack, 9:05am March 15 2013

    The most important of the paleoclimate reconstructions produced by Dr Mann and colleagues was published in the prominent journal "Proceedings of the National Academy of Sciences of the USA" on Sept. 2, 2008 (doi: 10.1073/pnas.0805721105). An expanded version of this work appeared in the US's #1 science journal, "Science," on Nov. 27, 2009 (doi: 10.1126/science.1177303). Both articles are heavily cited in the peer-reviewed literature and the general press.

    The "hockey stick" shape of the reconstructions in these two articles is entirely dependent on the inclusion of a single data set: measurements of sediment cores from Lake Korttajarvi in Southern Finland that were reported by geologist Mia Tiljander in 2003 (doi: 10.1111/j.1502-3885.2003.tb01236.x).

    If the "Tiljander proxies" are excluded, none of the analytical procedures in Mann et al (PNAS, 2008) or Mann et al (Science, 2009) return a hockey-stick shape with statistical significance.

    Three points to consider. (1) Tiljander noted that her dataset was unsuitable for use as a climate proxy after about 1720, since land-use changes and water pollution overwhelmed any climate signals in the 19th and 20th centuries.

    (2) The PNAS and the Science papers used two of the Tiljander proxies in an inverted (upside-down) orientation, with respect to the interpretation that Tiljander gave to them. This ad hoc decision was likely the result of ignorance and carelessness on the part of Dr Mann and his coauthors.

    (3) In interviews, at his blog, and in his book, Dr Mann "neither confirms nor denies" the interpretations I have presented in this comment.