Congressional Investigations
The increasing politicisation of the issue was demonstrated when, on 23 June 2005, Rep. Joe Barton, chairman of the House Committee on Energy and Commerce wrote joint letters with Ed Whitfield, Chairman of the Subcommittee on Oversight and Investigations, referring to issues raised by the 14 February 2005 article in the Wall Street Journal and demanding full records on climate research. The letters were sent to the IPCC Chairman Rajendra Pachauri, National Science Foundation Director Arden Bement, and to the three scientists Mann, Bradley and Hughes. The letters told the scientist to provide not just data and methods, but also personal information about their finances and careers, information about grants provided to the institutions they had worked for, and the exact computer codes used to generate their results.
Sherwood Boehlert, chairman of the House Science Committee, told his fellow Republican Joe Barton it was a "misguided and illegitimate investigation" into something that was not under the jurisdiction of the Science Committee, and "My primary concern about your investigation is that its purpose seems to be to intimidate scientists rather than to learn from them, and to substitute congressional political review for scientific review." Barton's committee spokesman sent a sarcastic response to this and to Democrat Henry A. Waxman's letter asking Barton to withdraw the letters and saying he had "failed to hold a single hearing on the subject of global warming" during eleven years as chairman, and had "vociferously opposed all legislative efforts in the Committee to address global warming .... These letters do not appear to be a serious attempt to understand the science of global warming. Some might interpret them as a transparent effort to bully and harass climate change experts who have reached conclusions with which you disagree." The U.S. National Academy of Sciences (NAS) president Ralph J. Cicerone wrote to Barton that "A congressional investigation, based on the authority of the House Commerce Committee, is probably not the best way to resolve a scientific issue, and a focus on individual scientists can be intimidating", and proposed that the NAS should appoint an independent panel to investigate. Barton dismissed this offer.
On 15 July, Mann wrote giving his detailed response to Barton and Whitfield. He emphasised that the full data and necessary methods information was already publicly available in full accordance with National Science Foundation (NSF) requirements, so that other scientists had been able to reproduce their work. NSF policy was that computer codes "are considered the intellectual property of researchers and are not subject to disclosure", as the NSF had advised McIntyre and McKitrick in 2003, but notwithstanding these property rights, the program used to generate the original MBH98 temperature reconstructions had been made available at the Mann et al. public ftp site. Following receipt of responses to the letters, Barton and Whitfield had their committee staff contact statistician Edward J. Wegman for advice on the validity of McIntyre and McKitrick's complaints, and Wegman formed an ad-hoc committee consisting of himself, David W. Scott and Yasmin H. Said.
Many scientists protested, with 20 prominent climatologists writing to Barton questioning his approach. Alan I. Leshner wrote to him on behalf of the American Association for the Advancement of Science expressing deep concern about the letters, which gave "the impression of a search for some basis on which to discredit these particular scientists and findings, rather than a search for understanding." He stated that MBH had given out their full data and descriptions of methods, and were not the only evidence in the IPCC TAR that recent temperatures were likely the warmest in 1,000 years; "a variety of independent lines of evidence, summarized in a number of peer-reviewed publications, were cited in support". Thomas Crowley argued that the aim was intimidation of climate researchers in general, and Bradley thought the letters were intended to damage confidence in the IPCC during preparation of its next report. A Washington Post editorial on 23 July which described the investigation as harassment quoted Bradley as saying it was "intrusive, far-reaching and intimidating", and Alan I. Leshner of the AAAS describing it as unprecedented in in the 22 years he had been a government scientist; he thought it could "have a chilling effect on the willingness of people to work in areas that are politically relevant." Benjamin D. Santer told the New Scientist "There are people who believe that if they bring down Mike Mann, they can bring down the IPCC."
Congressman Boehlert said the investigation was as "at best foolhardy" with the tone of the letters showing the committee's "inexperience" in relation to science. Barton was given support by global warming sceptic Myron Ebell of the Competitive Enterprise Institute, who said "We've always wanted to get the science on trial ... we would like to figure out a way to get this into a court of law", and "this could work". In in his Junk Science column on Fox News, Steven Milloy said Barton's inquiry was reasonable.
The July 2005 issue of the Journal of Climate published a paper it had accepted for publication the previous September, co-authored by Scott Rutherford, Mann, Osborn, Briffa, Jones, Bradley and Hughes, which examined the sensitivity of proxy based reconstruction to method and found that a wide range of alternative statistical approaches gave nearly indistinguishable results. In particular, omitting principal component analysis made no significant difference. In comments on MM05 made in October, Peter Huybers showed that McIntyre and McKitrick had omitted a critical step in calculating significance levels, and MBH98 had shown it correctly. In their comment, Hans von Storch and Eduardo Zorita examined McIntyre and McKitrick's claim that normalising data prior to principal component analysis by centering in relation to the calibration period of 1902–1980, instead of the whole period, would nearly always produce hockey stick shaped leading principal components. They found that it caused only very minor deviations which would not have a significant impact on the result.
In November 2005, Science Committee chair Sherwood Boehlert requested the National Academy of Science to arrange a review of the matter. The National Research Council set up a special committee to investigate.
Read more about this topic: Hockey Stick Controversy