Michael Mann faces off with foes on 'Hockey Stick' tour

USA Today: The "Hockey Stick" - the term given to a graph depicting the globe's average temperatures over the last millennium, looking like a flat shaft with a "blade" spiking upward at the end of the 20th Century - made Penn State's Mann and his colleagues into magnets for controversy among climate naysayers. Largely, they criticized the hockey stick's stark depiction, based for the most part on tree-ring data, of rising temperatures driven by global warming. The graph became famous after it appeared in a...

URL: http://www.usatoday.com/tech/science/columnist/vergano/story/2012-04-20/global-warming-climate-wars/54454322/1