The IPCC Third Assessment Report showed a graph labeled `` Millennial Northern Hemisphere temperature reconstruction '' from a paper by Mann , Bradley and Hughes ( MBH98 ) often called the `` Hockey Stick Graph '' . The third assessment report ( TAR ) prominently featured a graph labeled `` Millennial Northern Hemisphere temperature reconstruction '' from a 1999 paper by Michael E. Mann , Raymond S. Bradley and Malcolm K. Hughes ( MBH99 ) often referred to as the `` Hockey Stick Graph '' .