NASA's top climate scientist said the Bush administration has tried to stop him from speaking out since he gave a lecture in December calling for prompt reductions in emissions of greenhouse gases, The New York Times said on Saturday.
In an interview with the newspaper, James Hansen, director of NASA's Goddard Institute for Space Studies, said that officials at the space agency's headquarters had ordered the public affairs staff to review his lectures, papers, postings on the Goddard Web site and requests for interviews from journalists.
"They feel their job is to be this censor of information going out to the public," the Times quoted Hansen as saying, adding that the scientist planned to ignore the new restrictions.
A NASA spokesman denied any effort to silence Hansen, the Times said. "That's not the way we operate here at NASA," said Dean Acosta, deputy assistant administrator for public affairs. "We promote openness and we speak with the facts."
Rather, the spokesman said the restrictions applied to any and all NASA personnel who could be seen by the public as speaking for the agency. Acosta added, however, that while government scientists were free to discuss scientific findings, policy statements should be left to policy makers and appointed spokesmen, the Times said.
The story was posted on its Web site and will be published in Sunday's editions.
Hansen, a physicist who joined the space agency in 1967, is an authority on climate who directs efforts to simulate the global climate on computers at Manhattan's Goddard Institute.
Since 1988 he has warned publicly about the long-term threat from heat-trapping emissions, dominated by carbon dioxide, that are a byproduct of burning coal, oil and other fossil fuels, The Times said.
It said he fell out of favor with the White House in 2004 after a University of Iowa speech ahead of the presidential election in which he complained that government climate scientists were being muzzled, adding that he planned to vote for Democratic nominee Sen. John Kerry.
Hansen told the Times over the course of several interviews that an effort began in early December to keep him from publicly discussing what he says are clear-cut dangers from further delay in curbing carbon dioxide.
Hansen said the recent efforts to quiet him began after a lecture he gave on December 6 at the annual meeting of the American Geophysical Union in San Francisco in which he said that significant emission cuts could be achieved with existing technologies, particularly in the case of motor vehicles.
Without leadership by the United States, he told The Times, climate change would eventually leave the earth "a different planet."
Hansen said that NASA headquarters officials repeatedly phoned public affairs officers, who warned Hansen of "dire consequences" if such statements continued. The officers confirmed the warning to the Times.
The Bush administration's policy is to use voluntary measures to slow, but not reverse, the growth of emissions, the paper said.