Climategate: Scientists Fabricated Climate Data (2009)

Introduction

In November 2009, a server at the University of East Anglia's (UEA) Climatic Research Unit (CRU) was hacked and approximately 1,000 emails and 3,000 other documents were leaked online. The timing — just weeks before the Copenhagen climate summit — was widely noted. Critics, primarily in conservative media and climate-sceptic blogosphere, argued that selected phrases from the emails proved that climate scientists had fabricated, manipulated, or suppressed data to create a false impression of global warming. The episode was quickly labelled "Climategate" by analogy with Watergate.

The core claim — that scientists falsified data — has been examined by five independent inquiries across two continents and found to be false. This page explains what the emails actually said, what the investigations found, and why the conspiracy framing fails.

The Leaked Emails: What Were the Phrases?

Two phrases attracted most attention:

"Mike's Nature Trick"

An email from CRU director Phil Jones referred to using "Mike's Nature trick" to "hide the decline." Critics presented this as an admission of deliberate deception. In context:

• "Mike's Nature trick" referred to a method published by Michael Mann in Nature in 1998: combining tree-ring proxy records with the modern instrumental temperature record (a standard, openly published technique for visualising multi-century temperature reconstructions).
• The word "trick" in scientific correspondence commonly means a clever analytic technique, not a deception.
• The technique was published and peer-reviewed, not concealed.

"Hide the Decline"

This phrase referred to a specific known problem in dendrochronology: tree-ring data from certain high-latitude and high-altitude sites shows an anomalous decline after approximately 1960, diverging from the instrumental temperature record. This "divergence problem" was openly discussed in published literature — it was not a secret. Jones's email discussed how to present the data clearly without the divergence artefact obscuring the modern temperature signal. The "decline" being hidden was a known proxy anomaly, not a decline in global temperatures.

The Five Independent Investigations

Following the leak, five independent panels investigated the allegations of scientific misconduct:

1. UK House of Commons Science and Technology Committee (March 2010)

The committee examined the emails and the conduct of CRU scientists. It found no evidence that Jones had manipulated data or acted improperly, though it criticised the university's response to Freedom of Information requests. It concluded that Jones's scientific reputation remained intact.

2. Independent Climate Change Email Review — Muir Russell (July 2010)

Sir Muir Russell, a former vice-chancellor, led a panel that reviewed the emails and interviewed scientists at length. The review found: "We saw no evidence of any deliberate scientific malpractice in any of the work of the Climatic Research Unit." It found that the rigour and honesty of the CRU scientists were not in doubt. It criticised the scientists for insufficient openness about sharing data and code, but explicitly distinguished this from scientific fraud.

3. Science Assessment Panel — Oxburgh Report (April 2010)

Lord Oxburgh chaired a review of the scientific work itself, examining eleven papers. The panel found no evidence of scientific misconduct or data manipulation. It concluded that the science was "conducted with integrity."

4. Penn State University investigation (July 2010)

Penn State University investigated Michael Mann (whose "trick" was cited in the emails). The inquiry found no credible evidence that Mann had engaged in, or participated in, falsification of research data, destruction of emails, misuse of confidential information, or deviation from accepted practices. Mann was cleared on all four charges.

5. NOAA Inspector General (February 2011)

The US National Oceanic and Atmospheric Administration conducted its own independent review of the temperature data itself. It found no evidence of impropriety or that NOAA's temperature records had been manipulated.

All five panels reached the same conclusion: no data fabrication, no scientific misconduct.

Why the Underlying Science Has Not Changed

The climate-sceptic framing assumed that the CRU temperature record was uniquely central to global warming evidence, and that discrediting it would unravel the science. This assumption was wrong for several reasons:

• Multiple independent datasets. NOAA, NASA GISS, the Japan Meteorological Agency (JMA), Berkeley Earth (an independent project funded partly by sceptic-affiliated sources), and others have all produced temperature reconstructions. They converge closely despite being derived from independent station networks and different methodologies.
• Berkeley Earth. Richard Muller, a physicist who had been publicly sceptical of the temperature record before 2012, led an independent reanalysis funded in part by the Koch-affiliated foundations. Berkeley Earth confirmed the warming trend. Muller subsequently stated publicly that he had been wrong to be sceptical.
• Post-Climategate observations. Every year since 2009 has confirmed continued warming: 2023 and 2024 were the two hottest years in the global instrumental record. 17+ years of post-Climategate observations have validated the projections.

What the Emails Did Reveal (The Legitimate Concerns)

The investigations were not exonerations without reservation:

• Insufficient data sharing. Multiple panels criticised CRU for resisting Freedom of Information requests and not proactively sharing raw data and code. This is a legitimate scientific-transparency criticism.
• Tone in peer review discussions. Some emails showed scientists discussing ways to prevent specific papers they considered poor quality from appearing in journal literature, raising questions about appropriate peer-review conduct.
• The divergence problem in public communication. Some panels noted that clearer public communication of the tree-ring divergence problem would have pre-empted some of the misrepresentation.

These criticisms are valid. They do not support the fabrication claim.

Why It Was Effective Disinformation

Climategate was a case study in effective selective quotation. The phrases were short, memorable, and superficially damaging when stripped of context. The rebuttals required understanding dendrochronology, proxy reconstruction methodology, and the history of atmospheric physics — technical knowledge the general public could not be expected to possess. The timing (weeks before Copenhagen) maximised political impact. The narrative was picked up internationally and continues to circulate despite the investigation outcomes.

Verdict

Debunked. Five independent panels cleared the scientists of data fabrication and misconduct. The specific phrases cited by critics had mundane professional meanings. Independent temperature datasets from NOAA, NASA GISS, Berkeley Earth, JMA, and others validate the underlying science. Post-2009 observations have confirmed continued warming. The most the investigations found was insufficient data-sharing transparency — a real criticism that falls far short of fabrication.

The May 2008 "Delete Any Emails" Message

One leaked message was not about scientific method at all but about conduct. On 29 May 2008, Phil Jones wrote to Michael Mann: "Can you delete any emails you may have had with Keith re AR4? Keith will do likewise ... We will be getting Caspar to do likewise." This is a genuine quote, and it is the single most damaging item in the archive: Times Higher Education reported that the UK Information Commissioner's Office (ICO) formally found UEA had broken the Freedom of Information Act over this period, with Deputy Information Commissioner Graham Smith stating the Act makes it an offence for a public authority to act so as to intentionally prevent disclosure of requested information. No prosecution followed, but only because the Act imposes a strict six-month limit for bringing charges, and that window had already closed by the time investigators identified the conduct — not because the underlying request to delete records was found to be innocent. UEA said no emails were actually deleted, and the later Penn State inquiry found Mann had preserved and produced his full AR4-era archive on request. Every inquiry treated this episode as a genuine FOI-compliance failure, distinct from the question this page addresses: whether the temperature data itself was fabricated or manipulated. On that specific question, none of the five inquiries found evidence of impropriety.

The "Redefine Peer-Review" Line

A second widely quoted line came from a 2004 Jones email discussing two papers he considered scientifically weak: "I can't see either of these papers being in the next IPCC report. Kevin and I will keep them out somehow — even if we have to redefine what the peer-review literature is!" Critics read this as an admission of a plan to rig the IPCC's assessment process. In fact, as FactCheck.org documented, both disputed papers were subsequently cited in IPCC Fourth Assessment Report working-group volumes, undercutting the claim that they were successfully suppressed. Jones later told Nature that the IPCC report "is an assessment, it's not a review," meaning lead authors are expected and required to weigh the quality of competing literature rather than cite it indiscriminately. The House of Commons and Muir Russell panels examined this and similar passages and did not find that the peer-review or IPCC assessment process had actually been corrupted, while still criticising the combative tone CRU scientists used toward papers and journals they disagreed with.

Reading the Real Quotes in Context

None of this changes the verdict. The most individually damaging-sounding lines in the archive — on deleting emails ahead of FOI requests, on keeping disputed papers out of an IPCC chapter, and on the tree-ring divergence problem discussed above — describe real disputes over transparency, tone, and journal politics that five separate inquiries examined in detail. Those inquiries drew a consistent line between legitimate criticism of institutional conduct and the specific conspiracy claim under review here, that scientists fabricated the underlying warming data. They found evidence for the former in places and no evidence at all for the latter.