The US Congress's most ardent global warming skeptic is being accused of turning the row over climate science into a McCarthyite witch-hunt by calling for a criminal investigation of scientists.
Climate scientists say Senator James Inhofe's call for a criminal investigation into American as well as British scientists who worked on the UN climate body's report or had communications with East Anglia's climate research unit represents an attempt to silence debate on the eve of new proposals for a climate change law.
Inhofe's document ends by naming 17 "key players" in the controversy about CRU's stolen emails, including the Britons Phil Jones and Keith Briffa.
"I think this is like a drag net, just to try and catch everyone whose name happens to be on this list. It's guilt by association and I thought those days were over 50 years ago," said Michael Oppenheimer, of Princeton University, who is on the list of 17 scientists. "It looks like a McCarthyite tactic: pull in anyone who had anything to do with anyone because they happened to converse with some by email, and threaten them with criminal activity."
Inhofe is also accused of further fuelling a spike in hate mail and politically motivated freedom of information requests in the three months since the emails of climate scientists were stolen from the University of East Anglia's Climatic Research Unit.
Rick Piltz, a former official in the US government climate science program who now runs the Climate Science Watch website, said Inhofe and others were getting in the way of scientific work. "Scientists who are working in federal labs are being subjected to inquisitions coming from Congress," he said. "There is no question that this is an orchestrated campaign to intimidate scientists."
Michael Mann, a scientist at Penn State University who is on Inhofe's list of 17, said that he had seen a sharp rise in hostile email since November.
"Some of the emails make thinly veiled threats of violence against me and even my family, and law enforcement authorities have been made aware of the matter," he told the Guardian.
He said the attacks appeared to be a co-ordinated effort. "Some of them look cut-and-paste."
A university investigation largely cleared Mann of misconduct for his connection to the East Anglia controversy. However, a rightwing group in Pennsylvania are demanding further action.
Gavin Schmidt, a climate scientist at NASA's Goddard Institute who is also on the list of 17, said he had seen an increase in freedom of information act requests. "In my previous six years I dealt with one FoIA request. In the last three months, we have had to deal with I think eight," he said. "These FoIAs are fishing expeditions for potentially embarrassing content but they are not FoIA requests for scientific information."
He said Inhofe's call for a criminal investigation created an atmosphere of intimidation. "The idea very clearly is to let it be known that should you be a scientist who speaks out in public then you will be intimidated, you will be harassed, and you will be threatened," he said. "The idea very clearly is to put a chilling effect on scientists speaking out in public and to tell others to keep their heads down. That kind of intimidation is very reminiscent of other periods in US history where people abused their position."
Other scientists on Inhofe's list of 17 admitted they were disturbed by the threat of criminal prosecution.
"I am worried about it, I have to say," said Raymond Bradley, director of the climate science research center at the University of Massachusetts Amherst, who is also on the list of 17. "You can understand that this powerful person is using the power of his office to intimidate people and to harass people and you wonder whether you should have legal counsel. It is a very intimidating thing and that is the point."
Inhofe, an Oklahoma Republican on the Senate's environment and public works committee, released a document last week suggesting scientists be investigated for breaking three laws and four government regulations.
The document, produced by members of Inhofe's staff, recycles now familiar skeptic arguments about the stolen emails from East Anglia and the mistakes in the IPCC report.
But climate scientists say the report takes the campaign to a new level by threatening criminal prosecution. The report calls for the inspector generals of all US government agencies touching on the environment to investigate the scientists as a first step to possible prosecution.
"The minority staff of the Senate committee on environment and public works believe the scientists involved violated fundamental ethical principles governing taxpayer-funded research and, in some cases, may have violated federal laws," the report says.
A spokesman for Inhofe rejected the charges of a witch-hunt. But he said a criminal investigation was warranted and that it should not necessarily be limited to the 17 "key players".
"We are not saying that there are 17 scientists we should be calling criminals," said Matt Dempsey, a spokesman for Inhofe. "I'm not putting a number on 17."
He added: "The bottom line though is that there was manipulation of data and it appears that they violated a law." "In terms of what these email demonstrate, there are possible criminal violations here with FoIA and other laws."
Senate leaders are expected to release new proposals for action on climate change as early as this week. Environmentalists fear the proposal, crafted by a troika of Democratic, Republican, and Independent senators, would weaken a climate change bill passed by the house last June.
The Washington Post reported at the weekend that the senators could scrap a cap-and-trade bill that was the core of the house bill and bring in more limited measures.