"There's simply no bigger challenge we face," he said. "The stakes could not be higher."

BSkyB, which is 38 percent owned by US entertainment conglomerate News Corp., describes itself as the world's first media company to become carbon neutral, meaning it pays others to cut emissions on its behalf. The company has about 8.2 million subscribers to its satellite TV services.

BSkyB's emissions over the past year were 41,000 tonnes of carbon dioxide (CO2), said Murdoch, a small amount by comparison with the emissions of big polluters such as power generators.

Murdoch said cutting or offsetting emissions were good for business, improving energy efficiency and chiming with public concerns about climate change.

He rejected criticism that such efforts smacked of "greenwash" or "tokenism".

He said that reporting of the threat of climate change had been muddied by big business lobbyists and the need to be seen to offer balanced journalism.

"The issue is being confused by....large corporate lobbyists selling doubt."

Murdoch mentioned an advert now running in the US and sponsored by the Competitive Enterprise Institute, with the strap line "carbon dioxide: we call it life".

The world would be so cold as to be uninhabitable if there was no CO2, the commonest of the heat-trapping gases called greenhouse gases.