---
title: "Climatic Research Unit email controversy"
chunk: 2/12
source: "https://en.wikipedia.org/wiki/Climatic_Research_Unit_email_controversy"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:22:41.916840+00:00"
instance: "kb-cron"
---

The material comprised more than 1,000 emails, 2,000 documents, as well as commented source code pertaining to climate-change research, covering the period from 1996 to 2009. According to an analysis in The Guardian, the vast majority of the emails were from or to four climatologists: Phil Jones, the head of the CRU; Keith Briffa, a CRU climatologist specialising in tree ring analysis; Tim Osborn, a climate modeller at CRU; and Mike Hulme, director of the Tyndall Centre for Climate Change Research. The four were either recipients or originators of all but 66 of the 1,073 emails, with most of the remainder of the emails being sent from mailing lists. A few other emails were sent by, or to, other staff at the CRU. Jones, Briffa, Osborn and Hulme had written high-profile scientific papers on climate change that had been cited in reports by the Intergovernmental Panel on Climate Change.
Most of the emails concerned technical and mundane aspects of climate research, such as data analysis and details of scientific conferences. The Guardian's analysis of the emails suggests that the hacker had filtered them. Four scientists were targeted and a concordance plot shows that the words "data", "climate", "paper", "research", "temperature" and "model" were predominant. The controversy has focused on a small number of emails with climate change denier websites picking out particular phrases, such as one in which Kevin Trenberth said, "The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't". This was actually part of a discussion on the need for better monitoring of the energy flows involved in short-term climate variability, but was grossly mischaracterised by critics.

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. The "trick" was a technique to combine instrumental temperature record data with long term reconstructions, and "the decline" referred to the tree-ring divergence problem, which had already been openly discussed in scientific papers, but these two phrases were taken out of context by commentators promoting climate change denial, including US Senator Jim Inhofe and former Governor of Alaska Sarah Palin, as though the phrases referred to some decline in measured global temperatures, even though they came from an email written at a time when temperatures were at a record high.
John Tierney, writing in The New York Times in November 2009, said that the claims by sceptics of "hoax" or "fraud" were incorrect, but that the graph on the cover of a report for policy makers and journalists did not show these non-experts where proxy measurements changed to measured temperatures. The final analyses from various subsequent inquiries concluded that in this context "trick" was normal scientific or mathematical jargon for a neat way of handling data, in this case a statistical method used to bring two or more different kinds of data sets together in a legitimate fashion. The EPA notes that in fact, the evidence shows that the research community was fully aware of these issues and that no one was hiding or concealing them.
An Associated Press review of the emails concluded that they showed scientists fending off critics, stating that "One of the most disturbing elements suggests an effort to avoid sharing scientific data with critics skeptical of global warming", and mentioned ethical problems with this action due to the fact that "free access to data is important so others can repeat experiments as part of the scientific method". They cited a science policy expert as stating that it was "normal science politics, but on the extreme end, though still within bounds".