Hollywood star Leonardo DiCaprio has called upon the media to take message of environmental activists seriously and not seek to highlight inconsistencies in their personal lives.
Actoptrnot hit back at accusations of hypocrisy as he unveiled an eco-documentary he wrote, produced and narrated at the Cannes film festival.
Asked after the premiere of The 11th Hour whether he had taken a fuel-guzzling jet on his way to the French Riviera, the Titanic star spat back sarcastically "No, I took a train across the Atlantic".
When the British journalist followed up, saying that many stars used emission-heavy private jets while touting environmental protection, a testy DiCaprio countered that he had taken a commercial flight from New York.
"I try to travel commercial as much as I can," he said.
DiCaprio later came back to the reporter, saying that he was irritated with the media for going after prominent environmentalists such as former US vice-president Al Gore (whose own film on global warming An Inconvenient Truth picked up an Oscar this year) for supposed inconsistency in their private lives.
"We're all trying the best we can, truly, we really are," he said.
"Attacks on Al Gore for example I think are misdirected. Don't shoot the messenger, you know what I'm saying? If you're going to attack somebody on the way they conduct their life, let's talk about the big picture, let's see what big oil companies are doing.
"This person is truly trying to relay a message to the public and the way he travels and the way he leads his life should not be splayed out like that."
DiCaprio, who described himself as an environmentalist for the last decade, got into hot water in 2000 when activists said that part of a Thai national park was damaged during the shooting of his film The Beach. The crew denied the accusations.
His film The 11th Hour presents a dozen experts arguing that human society will be wiped out if global warming continues unabated.
The film picks up many of the themes of An Inconvenient Truth, which was also an unexpected box office hit.
DiCaprio credited the picture with pushing the environment to the top of the US agenda.
"Certainly in the United States we are the ones that should set an example for the rest of the world. We are the most powerful democracy on the planet and we're also the largest polluters simultaneously," he said.
While Gore's film was an account of his personal crusade to change American public opinion about the urgency of the pollution crisis one audience at a time, The 11th Hour attempts to tackle even bigger questions.
DiCaprio brings in British physicist Stephen Hawking, former Soviet leader Mikhail Gorbachev and Kenyan Nobel peace laureate Wangari Maathai to argue his case that Western society should "consume less and live more".
Spliced between the interviews are apocalyptic visions of gurgling volcanoes, massive mudslides and clubbed baby seals, all set against images of America's insatiable consumerism.
DiCaprio said, despite the film's tone, he was optimistic about humanity's fate.
"I'm happy to be a part of this generation that talks about an issue that affects so many generations after us like global warming does. It's probably the biggest movement in human history, if done right," he said.