 The Hockey Stick Controversy. The hockey stick controversy focused on some of the first millennial-scale paleoclimate reconstructions of the evolution of Northern Hemisphere mean near-surface temperature. These reconstructions, when joined with the instrumental temperature record, indicate a long, slow decline in temperature followed by a sharp rise beginning around 1900; their shape is reminiscent of a hockey stick (e.g., Mann et al. 1998, 1999). Such reconstructions featured prominently in the IPCC’s Third Assessment Report (Albritton et al. 2001) and constituted part of the evidence for the IPCC conclusion that “the 1990s are likely to have been the warmest decade of the millennium” (Folland et al. 2001: 102). Contrarian criticism in the published literature followed two main lines. One argued that there were problems with the data and statistical methods used in producing the reconstructions (McIntyre &amp; McKitrick 2003, 2005), while a second appealed to additional proxy data and alternative methods for their interpretation in order to challenge the uniqueness of late-twentieth century warming (Soon et al. 2003). Mainstream climate scientists offered direct replies to these challenges (e.g., Mann et al. 2003; Wahl &amp; Ammann 2007), and additional research has since produced new and longer reconstructions using a variety of proxies, which also support the conclusion that the late twentieth century was anomalously warm (Masson-Delmotte et al. 2013).  [6]  Contrarians, however, continue to criticize temperature reconstructions and the conclusions drawn from them, on various grounds; a recent target was Marcott et al. 2013. Book length accounts of the controversy from opposing sides include Montford 2010 and Mann 2012.