Wegman Report

The Wegman Report (officially called the Ad Hoc Committee Report on the 'Hockey Stick' Global Climate Reconstruction) was prepared in 2006 by three statisticians led by Edward Wegman at the request of Rep. Joe Barton of the United States House Committee on Energy and Commerce to validate criticisms made by Stephen McIntyre and Ross McKitrick of reconstructions of the temperature record of the past 1000 years, in particular the reconstructions by Mann, Bradley and Hughes which had become the focus of the hockey stick controversy.

Background

Investigations of paleoclimate date back to the 1930s. but quantitative methods were slow to come into use. In the 1960s, Hubert Lamb generalised from historical documents and temperature records of central England to propose a Medieval Warm Period from around 900 to 1300, followed by Little Ice Age. This was the basis of a "schematic diagram" featured in the IPCC First Assessment Report beside cautions that the medieval warming might not have been global. The use of proxy indicators to get quantitative estimates of the temperature record of past centuries was developed, and Bradley & Jones 1993 introduced the "Composite Plus Scaling" (CPS) method used by most later large scale reconstructions.[1][2] Their study was featured in the IPCC Second Assessment Report, and in the United States House Committee on Science its findings were disputed by Pat Michaels.

In 1998 Michael E. Mann, Raymond S. Bradley and Malcolm K. Hughes developed new statistical techniques to produce Mann, Bradley & Hughes 1998 (MBH98), which showed global patterns of annual surface temperature, and included a graph of average hemispheric temperatures back to 1400 with shading emphasising that uncertainties (to two standard error limits) were much greater in earlier centuries.[3] Jones et al. 1998 independently produced a CPS reconstruction extending back for a thousand years, and Mann, Bradley & Hughes 1999 (MBH99) used the MBH98 methodology to extend their study back to 1000.[4][5] The term hockey stick was coined by the climatologist Jerry Mahlman, to describe the pattern this showed, envisaging a graph that is relatively flat to 1900 as forming an Ice hockey stick's "shaft", followed by a sharp increase corresponding to the "blade".[6][7] A version of this graph was featured prominently in the 2001 IPCC Third Assessment Report (TAR), which also drew on Jones et al. 1998 and three other reconstructions to support the conclusion that, in the Northern Hemisphere, the 1990s was likely to have been the warmest decade and 1998 the warmest year during the past 1,000 years.[5] The graph was featured in publicity, and became a focus of dispute for those opposed to the strengthening scientific consensus that late 20th century warmth was exceptional.[8]

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".[9]

Later in 2003, Stephen McIntyre and Ross McKitrick published McIntyre & McKitrick 2003 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.[10] 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 Huybers 2005 and Wahl & Ammann 2007 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.[11] Barton and U.S. Rep. Ed Whitfield requested Edward Wegman to set up a team of statisticians to investigate, and they supported McIntyre and McKitrick's view that there were statistical failings, although they did not quantify whether there was any significant effect. They also produced an extensive network analysis which has been discredited by expert opinion and found to have issues of plagiarism.

Congressional investigations

The increasing politicisation of the issue was demonstrated when,[12] 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.[13] 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.[14]

Sherwood Boehlert, chairman of the House Science Committee, told his fellow Republican Joe Barton it was a "misguided and illegitimate investigation" into something that should properly be under the jurisdiction of the Science Committee, and wrote "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.[15][16]

Mann, Bradley and Hughes sent formal letters giving their detailed responses to Barton and Whitfield. On 15 July, Mann wrote emphasising 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. [17]

Many scientists protested against Barton's investigation, with 20 prominent climatologists questioning his approach.[18] 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."[19] 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.[20] 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 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."[14] 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."[21]

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".[20] In his Junk Science column on Fox News, Steven Milloy said Barton's inquiry was reasonable.[22]

In November 2005, Science Committee chair Sherwood Boehlert requested the National Academy of Science to arrange a review of the matter, and its National Research Council set up a special committee to investigate and report.[23]

National Research Council Report

Main article: North Report

At the request of the U.S. Congress, initiated by Representative Sherwood Boehlert as chairman of the U.S. House of Representatives Committee on Science, a special "Committee on Surface Temperature Reconstructions for the Past 2,000 Years" was assembled by the National Research Council to quickly prepare a concise report. The NRC Committee, chaired by Gerald North, consisted of 12 scientists and statisticians from different disciplines. Its task was "to summarize current scientific information on the temperature record for the past two millennia, describe the main areas of uncertainty and how significant they are, describe the principal methodologies used and any problems with these approaches, and explain how central is the debate over the paleoclimate temperature record to the state of scientific knowledge on global climate change." [24] The NRC report went through a rigorous review process involving 15 independent experts.[25] 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.[26]

The NRC committee's report (the North Report) was published on 22 June 2006.[27] Committee member John Michael Wallace said that "Our conclusion is that this recent period of warming is likely the warmest in the last millennium", and added that "This doesn't change the scientific landscape in terms of the greenhouse warming debate".[28] In its summary, the NRC committee noted the development of large-scale surface temperature reconstructions, especially MBH98 and MBH99, and highlighted six recent reconstructions: Huang, Pollack & Shen 2000, Mann & Jones 2003, Hegerl et al. 2006, Oerlemans 2005, Moberg et al. 2005 and Esper, Cook & Schweingruber 2002. Its main findings were; 20th century instrumentally measured warming showed in observational evidence, and can be simulated with climate models, large-scale surface temperature reconstructions "yield a generally consistent picture of temperature trends during the preceding millennium", including the Medieval Warm Period and the Little Ice Age, "but the exact timing and duration of warm periods may have varied from region to region, and the magnitude and geographic extent of the warmth are uncertain." It concluded "with a high level of confidence that global mean surface temperature was higher during the last few decades of the 20th century than during any comparable period during the preceding four centuries", justified by consistent evidence from a wide variety of geographically diverse proxies, but "Less confidence can be placed in large-scale surface temperature reconstructions for the period from 900 to 1600", and very little confidence could be assigned to hemispheric or global mean surface temperature estimates before about 900.[29]

The NRC committee stated that "The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1,000 years. 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. It added that "Even less confidence can be placed in the original conclusions by Mann et al. (1999) that 'the 1990s are likely the warmest decade, and 1998 the warmest year, in at least a millennium' because the uncertainties inherent in temperature reconstructions for individual years and decades are larger than those for longer time periods and because not all of the available proxies record temperature information on such short timescales." It noted that "Surface temperature reconstructions for periods prior to the industrial era are only one of multiple lines of evidence supporting the conclusion that climatic warming is occurring in response to human activities, and they are not the primary evidence."[30]

At the press conference, North said of the MBH papers that "we do roughly agree with the substance of their findings. There is a small disagreement over exactly how sure we are."[31] All three from the NRC committee panel said it was probable, though not certain, that current warming exceeded any previous peak in the last thousand years.[23] When asked if they could quantify "less confidence" and "plausible", Bloomfield explained that their wording reflected the panel's scientific judgements rather than well defined statistical procedures, and "When we speak of 'less confidence' we're more into a level of sort of 2 to 1 odds, which IPCC, they interpreted 'likely' as that level, roughly 2 to 1 odds or better."[28][31]

Various criticisms of the MBH statistical methods were discussed in Chapter 11 in the context of more recent research which explored ways of addressing these problems, and showed greater amplitude of temperature variations over 1000 to 2000 years. Recent papers cited included Wahl & Ammann 2006 (in press). On McIntyre and McKitrick's criticism of principal component analysis as tending to bias the shape of the reconstructions, it found that "In practice, this method, though not recommended, does not appear to unduly influence reconstructions of hemispheric mean temperature", and reconstructions using other methods were qualitatively similar. Some of the criticisms of validation techniques were more valid than others, these issues and the effect on robustness of the choice of proxies contributed to the committee's view of increased uncertainties. They called for further research into methods and a search for more proxies for earlier periods.[32]

At the press conference the three NRC panellists said they found no evidence supporting the allegations of inappropriate behaviour such as data manipulation, or "anything other than an honest attempt to construct a data analysis procedure". Bloomfield as a statistician considered all the choices of data processing and methods to have been "quite reasonable" in a "first of its kind study". He said "I would not have been embarrassed by that work at the time if I'd been involved in it". In response to a question from Edward Wegman on the MBH use of principal components analysis, Bloomfield said this had been reviewed by the committee along with other statistical issues, and "while the issues are real, they had a very minimal effect, not a material effect on the final reconstruction."[31]

Committee on Energy and Commerce Report (Wegman Report)

Barton dismissed the offer of a joint investigation with an independent panel appointed by the U.S. National Academy of Sciences (NAS),[15] and on 1 September 2005 statistician Edward Wegman was contacted about giving testimony. Bardon's staffer then met Wegman, and explained that the United States House Energy Subcommittee on Oversight and Investigations wanted expert opinion on the validity of criticisms of the Mann, Bradley & Hughes 1999 reconstruction. Wegman set up a team of statisticians, and over the next nine months Barton's staffer provided them with material to review.[33] The team included Wegman, Yasmin H. Said who had been his graduate student, and statistician David W. Scott, all statisticians with no expertise in climatology or other physical sciences.[34] They were assisted by two others;[35] Wegman testified that one of his graduate students did the code for them,[36] and another of his graduate students provided a section of the report in draft, but was not an author of the report.[37]

Lacking Barton's agreement, Boehlert's Science Committee independently requested the NAS in November to commission the National Research Council Report. On 10 February 2006 the Wall Street Journal revealed Barton's contact with Wegman when it reported that "people familiar with the matter" said that Barton had already requested an analysis of the hockey stick from statistician Edward Wegman. It said that the deputy staff director for Barton's committee had made a statement that closer study was needed because of anticipated costs of mitigating climate change, and that Barton's concerns were "unlikely" to be fully addressed by the NAS.[38]

In an editorial dated 14 July 2006, the Wall Street Journal announced that a report commissioned by the Energy and Commerce Committee was due to be released that day. It gave a preview of the conclusions of the report, which had been prepared by three statisticians.[39] The committee chairman U.S. Rep. Joe Barton issued a press release giving a summary of the report's findings, with quotations from the report.[35][40]

The Wegman Report was not peer reviewed in the same way as the NRC Report, but was sent out to a number of referees before it was released. Wegman lacked the procedures and staff which the NRC had in place to organise peer review.[41] One of the referees, Grace Wahba, later said she was given the report only 3 days in advance, and her criticisms were ignored.[42]

Discussion and hearings

The Wegman Report was discussed at hearings of the United States House Energy Subcommittee on Oversight and Investigations under its chairman U.S. Rep. Ed Whitfield. The first hearing was held on 19 July 2006, five days after the report was announced and released.[39][43] Michael E. Mann was given only three days notice of the hearing and advised the committee that he was unable to attend on that date due to a commitment to look after his baby daughter, but the hearing went ahead with testimony from paleoclimatologist Tom Crowley who Mann recommended in his absence. The other scientists giving testimony were Gerald North, chairman of the National Research Council panel that had produced the NRC report, Tom Karl, director of the National Climatic Data Center, and Hans von Storch. Wegman and Steven McIntyre also testified at the hearing.[44][45]

A second hearing was arranged on 27 July 2006, and heard testimony from Mann, John Christy, a climate scientist at the University of Alabama in Huntsville, Ralph J. Cicerone, president of the National Academy of Sciences, and Jay Gulledge of the Pew Center on Global Climate Change. The hearing also heard testimony from Wegman and McIntyre.[45]

In an interview, North stated that the politicians at the hearing at which the Wegman Report was presented "were twisting the scientific information for their own propaganda purposes. The hearing was not an information gathering operation, but rather a spin machine."[41]

Issues raised by the Wegman Report

The report opened with a statement that its remit was to provide "an independent verification of the critiques" of MBH98 and MBH99 by McIntyre and McKitrick (MM), "as well as the related implications". They produced a social network analysis to imply problems of peer review not being independent, suggested that climatologists worked in isolation from statisticians, and alleged that there was inadequate sharing of methods and data.[47]

Critiques of MBH98 and MBH99 by McIntyre and McKitrick

Figure 4.5 p. 34 of the Wegman Report, "digitised" from "the temperature profile as presented in the IPCC Assessment Report 1990."

Peer review: social network analysis

Interactions between climatologists and statisticians

Sharing of data and methods

Plagiarism charges against Wegman

Wegman's institution, George Mason University, confirmed in October 2010 that they were investigating misconduct charges, following a March 2010 formal complaint by Raymond S. Bradley alleging plagiarism and fabrications in the Wegman Report. A 250-page study by computer scientist John Mashey, posted on the "Deep Climate" website, claims that 35 of the 91 pages in the Wegman Report were plagiarized, and "often injected with errors, bias and changes of meaning." Wegman responded that he was "very well aware of the report", but at the university's request would not comment further until all issues were settled.[72] Reviews by outside experts contacted by USA Today found plagiarism from textbooks which was obvious and inappropriate; the social network analysis section had also been partly copied from Wikipedia. Wegman said there was "speculation and conspiracy theory" in John Mashey's analysis, and said that "[t]hese attacks are unprecedented in my 42 years as an academic and scholar." He stated that the Wegman Report never "intended to take intellectual credit for any aspect of paleoclimate reconstruction science or for any original research aspect of social network analysis."[73]

Social network analysis paper

As an extension of the part of the Wegman Report which used social network analysis to suggest that there had been inappropriate close collaboration between some climate scientists, Wegman and Said published a paper (since retracted) in 2008 in the journal Computational Statistics & Data Analysis where they suggested "that certain styles of co-authorship lead to the possibility of group-think, reduced creativity, and the possibility of less rigorous reviewing processes". They concluded they had provided "insight into the why certain fields of study may have migrated into a more politically driven framework."[74] After computer scientist Ted Kirkpatrick of the Simon Fraser University read the "Deep Climate" website allegations of plagiarism, he made a formal complaint to the journal.[69] On 16 March 2011, Wegman sent an email to the journal saying that a student "had basically copied and pasted" work by other authors into the Wegman Report, and this text had been used in the journal paper without acknowledgement. He said that "We would never knowingly publish plagiarized material". In May 2011 the journal's editor, Stanley Azen of the University of Southern California, announced that the journal was retracting the paper, because it used portions of other authors' writings without sufficient attribution.[75] John Dahlberg of the United States Office of Research Integrity indicated that plagiarism could result in sanctions. A George Mason University spokesman declined to comment and said it was a "personnel matter".[69]

The manuscript of the paper had been submitted on 8 July 2007 and accepted for publication on 14 July 2007. Network analysis expert Kathleen Carley described it as an opinion piece which speculated that collaboration between scientists "leads to peer review abuse. No data is provided to support this argument". Wegman's student had attended a one-week course taught by Carley, thus becoming what Wegman described as the "most knowledgeable" of his contributors on the topic. Following the GMU inquiry, the student issued a statement that she had been "Dr. Wegman's graduate student when I provided him with the overview of social network analysis, at his request. My draft overview was later incorporated by Dr. Wegman and his coauthors into the 2006 report. I was not an author of the report." She had met with a GMU misconduct committee, and said that "My academic integrity is not being questioned."[37]

Disciplinary procedure

A Nature editorial commented on the implication that the plagiarised material in the retracted paper was likely to also be present in the earlier "infamous" Wegman Report, including allegations against Mann and his co-authors which had frequently been cited by climate-change sceptics. The George Mason University's policies indicated that its initial inquiry should have been completed within 12 weeks of the original complaint, and although 14 months had passed without this being resolved, there were loopholes for extensions. It said that the university should "take the initiative to move investigations along as speedily as possible while allowing time for due process. Once an investigation is complete, the institution should be as transparent as it can about what happened", especially where public funds were involved.[76]

George Mason University provost Peter Stearns announced on 22 February 2012 that charges of scientific misconduct had been investigated by two separate faculty committees, and that the one investigating the 2006 Wegman Report gave a unanimous finding that "no misconduct was involved". Stearns stated that "Extensive paraphrasing of another work did occur, in a background section, but the work was repeatedly referenced and the committee found that the paraphrasing did not constitute misconduct". He said that the 2008 social network analysis paper was investigated by a separate committee which unanimously found "that plagiarism occurred in contextual sections of the (CSDA) article, as a result of poor judgment for which Professor Wegman, as team leader, must bear responsibility", and Wegman was to receive an "official letter of reprimand". The investigation reports were to be sent on to federal authorities, but would not be made public. Bradley described the split result as "an absurd decision" which would encourage GMU students to think it acceptable to copy work without attribution.[77]

Notes

  1. ↑ Weart 2011c, Fingerprints (1990s-2000s)
  2. ↑ Jones et al. 2009.
  3. ↑ Wahl & Ammann 2007
  4. ↑ Weart 2011c, The Hockey Stick and Beyond
  5. 1 2 Folland et al. 2001, 2.3.2.2 Multi-proxy synthesis of recent temperature change
  6. ↑ Monastersky 2006, p. 10.
  7. ↑ BBC News, 16 July 2004.
  8. ↑ Pearce 2010_pt3 "Part three: Hockey stick graph took pride of place in IPCC report, despite doubts".
  9. ↑ Revkin, 5 August 2003 (NYT).
  10. ↑ The Decay of the Hockey Stick, Nature "Climate Feedback" blog post by von Storch. "... we do not think that McIntyre has substantially contributed in the published peer-reviewed literature to the debate about the statistical merits of the MBH and related method." (comment by von Storch & Zorita, May 7, 2007 07:35 PM, in response to multiple comments on their failure to acknowledge McIntyre and McKitrick's contributions)
  11. ↑ Pearce 2010_pt4, "Part four: Climate change debate overheated after sceptics grasped 'hockey stick'".
  12. ↑ Monastersky 2005.
  13. ↑ HCEC, 23 June 2005; Barton & Whitfield 2005.
  14. 1 2 Washington Post editorial, 23 July 2005, Hunting Witches".
  15. 1 2 Eilperin, 18 July 2005 (Washington Post).
  16. ↑ Waxman, 1 July 2005 (letter).
  17. ↑ Mann 2005; Schmidt & Rahmstorf 2005.
  18. ↑ Eilperin, 18 July 2005; Twenty scientists 2005.
  19. ↑ Leshner 2005. Leshner was CEO of the American Association for the Advancement of Science (AAAS) and Executive Publisher of the journal Science.
  20. 1 2 Pease, 18 July 2005 (BBC News).
  21. ↑ Pearce 2006
  22. ↑ Milloy, 31 July 2005 (Fox News).
  23. 1 2 Revkin, 22 June 2006 (NYT).
  24. ↑ North et al. 2006, pp. vii, Appendix C: Biosketches of Committee Members (142–146).
  25. ↑ North et al. 2006, pp. viii, xi
  26. ↑ North et al. 2006, pp. xiii–xiv, 28
  27. ↑ NAS press release, 22 June 2006.
  28. 1 2 Daley, 23 June 2006 (Boston Globe).
  29. ↑ North et al. 2006, pp. 1–3
  30. ↑ North et al. 2006, pp. 3–4
  31. 1 2 3 NAS press conference, 22 June 2006.
  32. ↑ North et al. 2006, pp. 112–116
  33. ↑ Said 2007
  34. ↑ Mann 2012, pp. 160, 357, Said 2005
  35. 1 2 3 HCEC "fact-sheet" 2006 (press release).
  36. ↑ HCEC Hearings, 19 July 2006, p. 750 (27 July).
  37. 1 2 3 Vergano, 16 May 2011.
  38. ↑ Regalado 2006a
  39. 1 2 WSJ editorial, 14 July 2006, Hockey Stick Hokum.
  40. 1 2 Wegman, Said & Scott 2006
  41. 1 2 North, interviewed by Monastersky, 6 Sept. 2006.
  42. 1 2 North 2006b, 22:10
  43. ↑ HCEC Hearings, 19 July 2006, p. 1.
  44. ↑ Mann 2012, pp. 166, 314–315
  45. 1 2 HCEC Hearings, 19 July 2006, p. III.
  46. ↑ 2006 Joint Statistical Meetings online program
  47. ↑ Wegman, Said & Scott 2006, pp. 1–5
  48. ↑ Wegman, Said & Scott 2006, pp. 4–5, 7
  49. ↑ Mongabay.com, 16 July 2006
  50. ↑ HCEC Hearings, 19 July 2006, pp. 697–698 (27 July).
  51. ↑ HCEC Hearings, 19 July 2006, p. 591.
  52. ↑ RealClimate, 19 July 2006.
  53. 1 2 Ritson 2006
  54. 1 2 HCEC Hearings, 19 July 2006, p. 769.
  55. ↑ HCEC Hearings, 19 July 2006, p. 258.
  56. ↑ Huybers 2005
  57. ↑ Mann 2012, pp. 131–136, 166–167, 315
  58. ↑ HCEC Hearings, 19 July 2006, pp. 212–213.
  59. 1 2 HCEC Hearings, 19 July 2006, p. 275.
  60. ↑ HCEC Hearings, 19 July 2006, p. 590.
  61. ↑ HCEC Hearings, 19 July 2006, p. 596.
  62. ↑ HCEC Hearings, 19 July 2006, pp. 698–700.
  63. ↑ HCEC Hearings, 19 July 2006, pp. 253–254.
  64. ↑ HCEC Hearings, 19 July 2006, pp. 700–702 (27 July).
  65. ↑ HCEC Hearings, 19 July 2006, pp. 84–85.
  66. ↑ HCEC Hearings, 19 July 2006, pp. 83, 98, 835–836.
  67. ↑ HCEC Hearings, 19 July 2006, pp. 63–64, 592.
  68. ↑ Quiggin 2006.
  69. 1 2 3 4 Vergano, 15 May 2011.
  70. ↑ HCEC Hearings, 19 July 2006, pp. 765–766.
  71. ↑ Mann & 2012 174–175, 318–319
  72. ↑ Vergano, 8 Oct. 2010; Vergano, 22 Nov. 2010.
  73. ↑ Vergano, 22 Nov. 2010 (USA Today).
  74. ↑ Said et al. 2008, pp. 2177, 2184.
  75. ↑ Kintisch 2011. See also the Elsevier retraction notice.
  76. ↑ Nature editorial, 26 May 2011 "Copy and paste".
  77. ↑ Vergano, 22 Feb. 2012.

References in chronological sequence

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1992

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1997

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External links

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