As lead author of a paper produced in 1998 with co-authors Raymond S. Bradley and Malcolm K. Hughes , Mann used advanced statistical techniques to find regional variations in a hemispherical climate reconstruction covering the past 600 years . In 1999 the same team used these techniques to produce a reconstruction over the past 1,000 years ( MBH99 ) which was dubbed the " hockey stick graph " because of its shape . He was one of eight lead authors of the " Observed Climate Variability and Change " chapter of the Intergovernmental Panel on Climate Change ( IPCC ) Third Scientific Assessment Report published in 2001 . A graph based on the MBH99 paper was highlighted in several parts of the report , and was given wide publicity . The IPCC acknowledged that his work , along with that of the many other lead authors and review editors , contributed to the award of the 2007 Nobel Peace Prize , which was won jointly by the IPCC and Al Gore
2007 Nobel Peace Prize
2007 Nobel Peace Prize
Michael E. Mann