Nasa climate reports 'swayed by politics'

• Ed Pilkington in New York
• The Guardian,

Political appointees placed by the Bush administration into senior positions within Nasa's media headquarters acted to play down and distort accounts given to the public of the research findings of its scientists on global warming, an official investigation has concluded.

The space agency's internal watchdog, the inspector general, reports that from autumn 2004 until early 2006 Nasa's central public affairs office handled global warming in a way that "reduced, marginalised, or mischaracterised climate change science made available to the general public".

The confirmation of political interference is vindication for James Hansen, Nasa's chief climate scientist and one of the first to sound the alarm over global warming. Claims of political dallying surfaced when Hansen said he had been blocked from taking part in a National Public Radio interview in December 2005.

In his report the inspector general, Kevin Winters, says he found no evidence of direct input by the White House in the handling of climate change science, and commends senior Nasa managers for acting swiftly once the allegations of censorship had been raised. But the report shows there was widespread belief among career Nasa press officers that the political appointees had created an "air of political interference" that stemmed from their desire to support the Bush administration by reducing the amount or toning down the impact of research on climate change disseminated to the public.

The report notes that the interference was perceived to have begun in the build-up to George Bush's re-election as president in November 2004.

The individual at the centre of the allegations was Dean Acosta, a senior public affairs officer appointed by Bush in 2003. He resigned in 2007. He and his fellow political appointees told the investigation they had edited scientific material in news releases in order to make it intelligible to the public, and denied any political incentive. Acosta, who now works for Boeing, told the New York Times that the report's criticisms were "patently false". "My entire career has been dedicated to open and honest communications," he said.

The report itemises ways in which information was allegedly blocked or twisted, including rewriting news releases to obscure or dilute scientists' findings, delaying releases, and putting them out when they would have reduced impact.