On 17 November 2009, the University of East Anglia discovered that an external attacker had accessed a CRU server and copied about 160 MB of material, including more than 1,000 emails, roughly 2,000 documents and research source code covering 1996–2009. The files were distributed online on 19 November, shortly before the Copenhagen climate summit began on 7 December. Critics, including Senator Jim Inhofe and former Alaska governor Sarah Palin, presented selected passages as evidence that CRU director Phil Jones and colleagues had manipulated temperature records, suppressed dissent and concealed a decline in global warming.
Subsequent reviews found no evidence of fraud or scientific misconduct. Investigations examined the disputed “Mike’s Nature trick” reference, which concerned combining proxy and instrumental datasets while acknowledging the tree-ring divergence problem, not hiding a fall in measured temperatures. The University of East Anglia’s Independent Climate Change Email Review reported on 7 July 2010, and an independent Science Assessment Panel reported on 14 April 2010; in total, eight committees found no basis for the central misconduct allegations. Norfolk Police closed its criminal investigation on 18 July 2012, citing no realistic prospect of identifying or prosecuting the attacker and no evidence of insider involvement. The breach exposed weaknesses in CRU’s data-security and Freedom of Information practices, while scientists received threats and abusive messages after the selective publication of the emails.
