EDIT
The most quoted soundbite in the affair comes from an email from Prof Phil Jones, director of the Climatic Research Unit at the University of East Anglia, to Prof Mike Mann of the University of Virginia in 1999, in which he discussed using "Mike's Nature trick" to "hide the decline". The phrase has been widely spun as an effort to prevent the truth getting out that global temperatures had stopped rising. The Alaska governor (ed - sic) Sarah Palin, in the Washington Post on 9 December, attacked the emailers as a "highly politicised scientific circle" who "manipulated data to 'hide the decline' in global temperatures". She was joined by the Republican senator James Inhofe of Oklahoma – who has for years used his chairmanship of the Environment and Public Works Committee to campaign against climate scientists and to dismiss anthropogenic global warming as "the greatest hoax ever perpetrated on the American people". During the Copenhagen climate conference, which he attended on a Senate delegation, he referred to Jones's "hide the decline" quote and said: "Of course, he means hide the decline in temperatures."
This is nonsense. Given the year the email was written, 1999, it cannot be anything of the sort. At that time there was no suggestion of a decline in temperatures. The previous year was the warmest on record. The full email from Jones says: "I've just completed Mike's Nature trick of adding in the real temps to each series for the last 20 years (ie from 1981 onwards) and from 1961 for Keith
's, to hide the decline."The decline being referred to was an apparent decline in temperatures shown in analysis of tree rings, which have historically correlated well with changes in temperature. That relationship has broken down in the past half century. The reasons are still debated.
The "trick" was a graphic device used by Mann in a 1998 paper in Nature to merge tree ring data from earlier times with thermometer data for recent decades. He explained it in the paper. Jones was repeating it in another paper. "This is a trick only in the sense of being a good way to deal with a vexing problem," Mann told the Guardian. Clearly, this problem with modern tree data raises questions about older data – at least until the reason for the divergence is nailed down. But it is not clandestine data manipulation, or, as claimed by Palin and Inhofe, a trick to hide global cooling. That charge is a lie. While he was in Copenhagen, Inhofe made a link between the "trick" to "hide the decline" and the second most popular soundbite. He said that "of course meant hide the decline in temperatures, which caused another scientist, Kevin Trenberth of the National Centre for Atmospheric Research in Boulder, Colorado, to write: 'The fact is we can't account for the lack of warming at the moment and it is a travesty that we can't.'"
The link is bogus. The two emails were 10 years apart. Unlike Jones, Trenberth's remark from October 2009 was indeed about the slackening of the warming trend that some like to interpret as cooling. That much is agreed. But Inhofe and other sceptics latched on to Trenberth's "travesty" phrase as a revelation that scientists were trying to keep cooling secret because it undermined their arguments about global warming. Again this is demonstrably false. Nothing was hidden. For months, Trenberth had been discussing publicly his concerns about the inability of scientists to pin down the precise reason for the "absence of warming" since 1998. He had argued in the journal Current Opinion in Environmental Stability in early 2009 that "it is not a sufficient explanation to say that a cool year is due to natural variability (pdf)". Such explanations "do not provide the physical mechanisms involved". This was the "travesty" he was referring to in his email. He wanted scientists to do better.He said the best way to improve the explanation and make it more specific was to make better measurements of the planet's energy budget. This would allow scientists to distinguish between any changes in the greenhouse effect, which would result in more or less heat overall in the atmosphere and oceans, and short-term natural cycles of variability, which merely redistribute heat. He was debating this with the former head of the Climatic Research Unit Tom Wigley, who took a different view. But their genuine scientific discussion has, since the publication of the emails online, been hijacked by ignorant or malicious invective.
EDIT
http://www.guardian.co.uk/environment/2010/feb/09/climategate-bogus-sceptics-lies