Fraser Forum Is the Climate Really Changing Abnormally?

• Main Author: Ross Mckitrick
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: ice core
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.184.7870; http://www.uoguelph.ca/%7Ermckitri/research/FFhockeystick.pdf

heard the striking claim that the 1990s were “very likely ” the warmest decade of the millennium, and 1998 was likely the warmest year. This claim was based on a “hockey stick” curve (see figure 1) from the 2001 Report of the UN’s Intergovernmental Panel on Climate Change (IPCC, 2001). The chart used temperature proxies, such as tree ring widths and ice core layering, to create a temperature index that appeared to slowly trail down for 900 years, then suddenly bend upwards around 1900. The graph was originally introduced by researcher Michael Mann and colleagues in 1998, and was extended in a subsequent paper (Mann et al., 1999). The hockey stick figure featured prominently in reports by the IPCC, appearing not only in figures 2.20 and 2.21 of the 2001 Working Group 1 Assessment Report, but also in figure 1 of the Summary for Policymakers, figure 5 of the Technical Summary, and twice (in figures 2-3 and 91b) in the Synthesis Report. Each time the figure is used it is large (sometimes more than half a page) and in bright colour. It is no exaggeration to say that the hockey-stick figure was the poster-child in the popular case against global warming. The Canadian government also made heavy use of this graph in its arguments for adopting the Kyoto Protocol. But is it true? That was the question that