The "Climategate" dispute over global warming science was reignited yesterday when thousands more hacked emails from climate researchers, some of them potentially damaging, were released online on the eve of a vital UN climate conference.
The private messages between senior scientists in Britain and America, hacked from the Climatic Research Unit (CRU) of the University of East Anglia (UEA), were released five days before delegates from nearly 200 countries meet in Durban, South Africa, in an effort to agree a new international global warming treaty to replace the Kyoto protocol, which runs out next year.
The emails' release was widely seen as an effort to destabilise the Durban meeting, as they were part of the same batch of emails originally hacked from the CRU's computers in November 2009 and released in an effort to damage the UN climate conference in Copenhagen the following month.
The 2009 hacking, which became known as "Climategate" and is still being investigated by the police, was seized on by climate sceptics who said the emails showed researchers manipulating data to support the theory that global warming was man-made and obstructing requests for information.
A series of reviews in Britain and the US later cleared researchers of any scientific impropriety and said the affair had not undermined the scientific basis of global warming, although the university was criticised for its failure to be sufficiently open and respond properly to Freedom of Information requests. Some of the emails did not show scientists in the best of lights and are likely to have contributed to a growth in climate scepticism.
In yesterday's release, a compressed zip file containing more than 5,000 further, hitherto unseen emails was suddenly made available to download on a Russian server – as had happened in 2009 – and links to the file were posted on climate-sceptic blogs.
This time those responsible, calling themselves FOIA, added a message appearing to equate fighting climate change with abandoning the fight against poverty.
Last night, UEA could not officially confirm that the emails were genuine, but the university said that they "had the appearance" of being part of the batch that was hacked two years ago.
The emails, which all date from before 2009, are apparently between some of the most senior figures in climate change research in the UK and the US, led by Professor Phil Jones, who was the head of the CRU at the time of the original hacking two years ago and who stood down from his post while the inquiries were carried out.
Other figures mentioned appeared to include Professor Jones's CRU colleague Dr Keith Briffa, Dr Peter Thorne of the UK Met Office and Sir John Houghton, formerly head of the Met Office and a leading figure in the IPCC.
In tone, the emails are very similar to the batch released in 2009, which means they may be embarrassing to some of the researchers concerned. Some of the messages show climate scientists squabbling, politicking, calling each other names and, in effect, plotting how to present their information in the best possible light.
But climate experts asserted that they did nothing to undermine global warming science. "The emails... do not raise any questions of substance that have not already been addressed by the independent inquiries into the original publication of hacked messages in November 2009," said Bob Ward at the London School of Economics' Grantham Research Institute on Climate Change.
"None of the inquiries found evidence of fraud or serious misconduct by climate researchers, but they did conclude that levels of transparency should be improved. These emails, like the last batch, show that climate researchers are human and prone to the same rivalries and disputes that occur in many professions."
Unscientific approach: The key players and damaging leaks
The key scientists, referred to only by surname in the leaked emails, are thought to be:
Phil Jones Director of the Climatic Research Unit at the University of East Anglia.
Peter Thorne Worked at the Met Office in the Climate Monitoring and Attribution group until 2010.
Geoff Jenkins Former head of climate change prediction at the Met Office's Hadley Centre.
Tom Wigley Senior scientist at the University Corporation for Atmospheric Research, Colorado.
Sir John Houghton Honorary scientist of the Hadley Centre and head of the Victoria Institute.
James Hansen Nasa's chief climate scientist and outspoken activist on global warming.
On the reliability of evidence
From Peter Thorne: Observations do not show rising temperatures throughout the tropical troposphere unless you accept one single study and approach and discount a wealth of others. This is just downright dangerous. We need to communicate the uncertainty and be honest. Phil, hopefully we can find time to discuss these further if necessary [...]
On melting tropical glaciers
From Geoff Jenkins: Would you agree that there is no convincing evidence for Kilimanjaro glaciermelt being due to recent warming (let alone man-made warming)? [The suggestion had been made that it was due to climate change.]
On the debate about cities being warmer than countryside
From Tom Wigley: There are some nitpicky jerks who have criticised the Jones et al. data sets – we don't want one of those [EPRI/California Energy Commission meeting].
From Phil Jones: The jerk you mention was called Good(e)rich who found urban warming at all Californian sites.
On climate and religion
From Sir John Houghton: We don't take seriously enough our God-given responsibility to care for the Earth [...] 500 million people are expected to watch The Day After Tomorrow. We must pray that they pick up that message.
On the effect of El Niño
From: Phil Jones
To: James Hansen
Keep up the good work! [...] Even though it's been a mild winter in the UK, much of the rest of the world seems coolish – expected though given the La Niña. Roll on the next El Niño!
On the threat from Freedom of Information requests
From Phil Jones: I've been told that IPCC is above national FOI Acts [Freedom of Information requests, forcing the handing-over of information to the public]. One way to cover yourself and all those working in AR5 would be to delete all emails at the end of the process.