In 2003 , as lobbying over the 1997 Kyoto Protocol intensified , Soon and Baliunas published a paper claiming greater medieval warmth , and on this basis the Bush administration chief of staff Philip Cooney deleted references to climate reconstructions from the first Environmental Protection Agency '' Report on the Environment '' . The paper was quickly dismissed by scientists in the Soon and Baliunas controversy , but on July 28 , Republican Jim Inhofe spoke in the Senate speech citing Soon and Baliunas to claim " that man-made global warming is the greatest hoax ever perpetrated on the American people " . Later in 2003 , Stephen McIntyre and Ross McKitrick published disputing the data used in MBH98 paper . They were given extensive publicity , and met Inhofe as well as making a presentation sponsored by the George C. Marshall Institute and the Competitive Enterprise Institute . In 2004 Hans von Storch published criticism of the statistical techniques as tending to underplay variations in earlier parts of the graph , though this was disputed and he later accepted that the effect was very small . In 2005 McIntyre and McKitrick published criticisms of the principal components analysis methodology as used in MBH98 and MBH99 . Their analysis was subsequently disputed by published papers including and which pointed to errors in the McIntyre and McKitrick methodology . In June 2005 Rep. Joe Barton launched what Sherwood Boehlert , chairman of the House Science Committee , called a " misguided and illegitimate investigation " into the data , methods and personal information of Mann , Bradley and Hughes . At Boehlert 's request a panel of scientists convened by the National Research Council was set up , which reported in 2006 supporting Mann 's findings with some qualifications , including agreeing that there were some statistical failings but these had little effect on the result . Barton and U.S. Rep. Ed Whitfield requested Edward Wegman to set up a team of statisticians to investigate . The Wegman Report supported McIntyre and McKitrick 's view that there were statistical failings , but did not quantify whether there was any significant effect . It included an extensive network analysis which has been discredited by expert opinion and found to have issues of plagiarism . Arguments against the MBH studies were reintroduced as part of the Climatic Research Unit email controversy , but dismissed by eight independent investigations
Climatic Research Unit email controversy
Climatic Research Unit email controversy
Temperature record of the past 1000 years