US climate scientists say they're experiencing a barrage of hate mail and death threats, and that law enforcement agencies are failing to act.
The Guardian has published a series of emails received since the recent controversy over climate research at the University of East Anglia.
The emails - uncensored - contain racist abuse as well as threats. Some of those interviewed by the paper say they've received hundreds.
"Go gargle razor blades, you f***ing bastard!!!!!!!!" reads one email. "I hope there is an earthquake right under your fucking house and swallows you into hell," says another.
But, say the scientists, First Amendment guarantees on freedom of speech mean that local law enforcement is unable to act.
Professor Stephen Schneider, a Stanford University climatologist, said his name had appeared on a neo-Nazi 'death list', but that the FBI had taken no action.
"Some of these people are mentally imbalanced. They are invariably gun-toting rightwingers," he says. "What do I do? Learn to shoot a Magnum? Wear a bullet-proof jacket?"
Michael Mann, who was recently cleared of misconduct by his university after claims he had massaged figures, recently told ABC News that he had received similar threats, including one urging him to commit suicide.
"It's an attempt to chill the discourse, and I think that's what's most disconcerting," he said.