A Disgrace to the Profession by Mark Steyn

Author:Mark Steyn [Steyn, Mark]
Language: eng
Format: epub
Publisher: Stockade Books
Published: 0101-01-01T00:00:00+00:00

61

“Mann et al used a type of principal component analysis that tends to bias the shape of the reconstructions.”

DR GERALD R NORTH, PHD ET AL

Gerald North is Distinguished Professor of Meteorology and Oceanography at Texas A&M University. Franco Biondi is Associate Professor of Physical Geography at the University of Nevada, Reno. Peter Bloomfield is Professor of Statistics at North Carolina State University, Raleigh. John Christy is director of the Earth System Science Center at the University of Alabama in Huntsville. Kurt Cuffey is Professor of Geography at the University of California, Berkeley. Robert Dickinson is a professor at Georgia Institute of Technology’s School of Earth and Atmospheric Sciences. Ellen Druffel is Professor of Earth System Science at the University of California, Irvine. Douglas Nychka is a senior scientist at NCAR (the National Center for Atmospheric Research). Bette Otto-Bliesner is a scientist in NCAR’s Climate and Global Dynamics Division. Neil Roberts is the head of the University of Plymouth’s School of Geography. Karl Turekian is the Sterling Professor of Geology and Geophysics at Yale University. John Wallace is Director of the Joint Institute for the Study of the Atmosphere and Ocean at the University of Washington, Seattle.

The first investigation into Mann’s stick was published by the National Research Council of the National Academies in June 2006. In its report on Surface Temperature Reconstructions for the Last 2,000 Years, Professor North and his colleagues concluded184:

~It can be said with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries. This statement is justified by the consistency of the evidence from a wide variety of geographically diverse proxies.

~Less confidence can be placed in large-scale surface temperature reconstructions for the period from AD 900 to 1600…

~Very little confidence can be assigned to statements concerning the hemispheric mean or global mean surface temperature prior to about AD 900 because of sparse data coverage and because the uncertainties associated with proxy data and the methods used to analyze and combine them are larger than during more recent time periods.

So “less confidence” for the years 900-1600 and “very little confidence” for pre-900 AD. So the only part of the hockey stick to which the NRC was prepared to give “a high level of confidence” was that late 20th century temperatures were the highest of the preceding four centuries - ie, since the Little Ice Age. That’s not a breakthrough finding by Michael Mann: It was the conventional wisdom long before Mann got his PhD - indeed, long before he was born. So for the NRC to give a clean bill of health to the hockey stick for the years 1600-1998 is equivalent to declaring that the hockey stick tells us nothing.

Along the way, however, the NRC makes some very telling criticisms of Mann. Page 113:

Mann et al used a type of principal component analysis that tends to bias the shape of the reconstructions.

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