It was disputed by various contrarians, and in the politicisation of this "hockey stick controversy" the New York Times of 14 February 2005 hailed a paper by businessman Stephen McIntyre and economist Ross McKitrick (MM05) as undermining the scientific consensus behind the Kyoto agreement.
On 23 June 2005, Rep. Joe Barton, chairman of the House Committee on Energy and Commerce, with Ed Whitfield, Chairman of the Subcommittee on Oversight and Investigations, wrote joint letters referring to issues raised by the Wall Street Journal article, and demanding that Mann, Bradley and Hughes provide full records on their data and methods, finances and careers, information about grants provided to the institutions they had worked for, and the exact computer codes used to generate their results.
[6] It broadly agreed with the basic findings of the original MBH studies, which subsequently been supported by other reconstructions and proxy records, while emphasising uncertainties over earlier periods.
[4] The report provided a summary and an overview, followed by 11 technical chapters covering the instrumental and proxy records, statistical procedures, paleoclimate models, and the synthesis of large scale temperature reconstructions with an assessment of the "strengths, limitations, and prospects for improvement" in techniques used.
[12] At a press conference, held on the same day, clarifications were given by three members of the NRC committee science panel: Gerald North, the statistician Peter Bloomfield and ice sheet/borehole specialist Kurt M.
This conclusion has subsequently been supported by an array of evidence that includes both additional large-scale surface temperature reconstructions and pronounced changes in a variety of local proxy indicators".
It said "Based on the analyses presented in the original papers by Mann et al. and this newer supporting evidence, the committee finds it plausible that the Northern Hemisphere was warmer during the last few decades of the 20th century than during any comparable period over the preceding millennium", though there were substantial uncertainties before about 1600.
[14] The report's overview section said that, despite the wide error bars, the hockey stick graph "was misinterpreted by some as indicating the existence of one 'definitive' reconstruction with small century-to-century variability prior to the mid-19th century".
Kurt Cuffey said the context was that the MBH work "...was really the first of its kind," and had generated debate in the normal process of science where ideas are put forward then challenged over time.
The IPCC 2001 report had been careful to give the two-year-old paper's conclusion fairly low confidence as "likely" at 2 to 1 odds, but use of the graph as a visual had created a misleading impression that this research was more resolved.
[9] Various criticisms of the MBH statistical methods were discussed in Chapter 11, in the context of more recent research that explored ways to address these problems, and showed greater amplitude of temperature variations over 1000 to 2000 years.
"[9] The U.S. House Science Committee Chairman Sherwood Boehlert issued a statement on the day of publication: "I think this report shows the value of Congress handling scientific disputes by asking scientists to give us guidance.
"[17] A group-authored post on RealClimate, of which Mann is one of the contributors, said "the panel has found reason to support the key mainstream findings of past research, including points that we have highlighted previously.
"[18] Similarly, Roger A. Pielke Jr. said that the National Research Council publication constituted a "near-complete vindication for the work of Mann et al.";[19] McIntyre's blog Climate Audit published a review of the report by Hans von Storch, Eduardo Zorita and Jesus Rouco, who said that it supported their view that the MBH methodology was questionable.
The original title of their 1999 paper (MBH99) was "Northern Hemisphere temperatures during the past millennium: inferences, uncertainties, and limitations", and it had concluded that "more widespread high-resolution data are needed before more confident conclusions can be reached".