[15] In response to the controversy, the American Association for the Advancement of Science (AAAS), the American Meteorological Society (AMS) and the Union of Concerned Scientists (UCS) released statements supporting the scientific consensus that the Earth's mean surface temperature had been rising for decades, with the AAAS concluding: "based on multiple lines of scientific evidence that global climate change caused by human activities is now underway... it is a growing threat to society".
[8] An anonymous post from a Saudi Arabian IP address[24] to the climate-sceptic blog The Air Vent[21] described the material as "a random selection of correspondence, code, and documents", adding that climate science is "too important to be kept under wraps".
[31][32] The most quoted email was one in which Phil Jones said that he had used "Mike's Nature trick" when preparing a graph as a 1999 cover illustration for the World Meteorological Organization "to hide the decline" in reconstructions based on tree-ring proxy data post-1960, when measured temperatures were actually rising.
Historian Spencer R. Weart of the American Institute of Physics said the incident was unprecedented in the history of science, having "never before seen a set of people accuse an entire community of scientists of deliberate deception and other professional malfeasance".
[48] The Wall Street Journal reported that the emails revealed apparent efforts to ensure that the IPCC included their own views and excluded others, and that the scientists withheld scientific data.
[52][40] In this context, John Tierney of The New York Times wrote: "these researchers, some of the most prominent climate experts in Britain and America, seem so focused on winning the public-relations war that they exaggerate their certitude – and ultimately undermine their own cause".
[53][needs update] Climate scientists in Australia have reported receiving threatening emails including references to where they live and warnings to "be careful" about how some people might react to their scientific findings.
Michael Mann, director of Pennsylvania State University's Earth System Science Center, said that sceptics were "taking these words totally out of context to make something trivial appear nefarious"[19] and called the entire incident a careful, "high-level, orchestrated smear campaign to distract the public about the nature of the climate change problem".
[65] Kevin E. Trenberth of the National Center for Atmospheric Research said that he was appalled at the release of the emails but thought that it might backfire against climate sceptics, as the messages would show "the integrity of scientists".
[66] Tom Wigley, a former director of the CRU and now head of the US National Center for Atmospheric Research, condemned the threats that he and other colleagues had received as "truly stomach-turning", and commented: "None of it affects the science one iota.
[70] One of the IPCC's lead authors, Raymond Pierrehumbert of the University of Chicago, expressed concern at the precedent established by this incident: "[T]his is a criminal act of vandalism and of harassment of a group of scientists that are only going about their business doing science.
"[71] Another IPCC lead author, David Karoly of the University of Melbourne, reported receiving hate emails in the wake of the incident and said that he believed that there was "an organised campaign to discredit individual climate scientists".
"[56] In response to the incident, 1,700 British scientists signed a joint statement circulated by the UK Met Office declaring their "utmost confidence in the observational evidence for global warming and the scientific basis for concluding that it is due primarily to human activities".
"[65] Hans von Storch, who also concurs with the mainstream view on global warming,[73] said that the University of East Anglia (UEA) had "violated a fundamental principle of science" by refusing to share data with other researchers.
"[43] On 5 December 2009, however, the Met Office indicated its intention to re-examine 160 years of temperature data in the light of concerns that public confidence in the science had been damaged by the controversy over the emails.
[18] However, the reports urged the scientists to avoid any such allegations in the future, and to regain public confidence following this media storm, with "more efforts than ever to make available all their supporting data – right down to the computer codes they use – to allow their findings to be properly verified".
They included submissions from the University of East Anglia, the Global Warming Policy Foundation, the Institute of Physics, the Royal Society of Chemistry, the Met Office, several other professional bodies, prominent scientists, some climate change sceptics, several MEPs and other interested parties.
The panel was also stated that "Although we deplore the tone of much of the criticism that has been directed at CRU, we believe that this questioning of the methods and data used in dendroclimatology will ultimately have a beneficial effect and improve working practices."
[64] Speaking at a press conference to announce the report, the panel's chair, Lord Oxburgh, stated that his team had found "absolutely no evidence of any impropriety whatsoever" and that "whatever was said in the emails, the basic science seems to have been done fairly and properly."
Mann subsequently told The Guardian that the study had been examined and approved in the US National Academies of Science North Report, and described Hand's comment as a "rogue opinion" not meriting "much attention or credence".
Describing its report as "hugely positive", he stated that "it is especially important that, despite a deluge of allegations and smears against the CRU, this independent group of utterly reputable scientists have concluded that there was no evidence of any scientific malpractice.
The committee did not make a definitive finding on the final point of inquiry – "whether Dr Mann seriously deviated from accepted practices within the academic community for proposing, conducting, or reporting research or other scholarly activities".
The committee said that the earlier NAS inquiry had found "that Dr Mann's science did fall well within the bounds of accepted practice", but in light of the newly available information this question of conduct was to be investigated by a second panel of five prominent Penn State scientists from other scientific disciplines.
[38][105] The second Investigatory Committee reported on 4 June 2010 that it had "determined that Dr Michael E. Mann did not engage in, nor did he participate in, directly or indirectly, any actions that seriously deviated from accepted practices within the academic community."
"[116] In a statement issued on 29 July 2010, EPA Administrator Lisa P. Jackson said the petitions were based "on selectively edited, out-of-context data and a manufactured controversy" and provided "no evidence to undermine our determination.
[122] The Office of the Inspector General (OIG) of the National Science Foundation closed an investigation on 15 August 2011 that exonerated Michael Mann of Pennsylvania State University of charges of scientific misconduct.
Phil Jones of CRU announced that requests were being made to all the National Meteorological Organisations for their agreement to waive confidentiality,[129] with the aim of publishing all the data jointly with the Met Office.
Physicist Mark Boslough of the University of New Mexico noted that many of the attacks on scientists came from "bloggers, editorial writers, Fox News pundits, and radio talk show hosts who have called them liars and vilified them as frauds".
In June 2021, the BBC reported that Climategate would be the subject of a film entitled The Trick with actors Jason Watkins, George MacKay, Victoria Hamilton, Jerome Flynn and Adrian Edmondson.
A. Leiserowitz, Director of the Yale University Project on Climate Change, and colleagues found in 2010 that:[6] Climategate had a significant effect on public beliefs in global warming and trust in scientists.