California set to cap emissions

It would make California the first US state to impose a cap on expulsion of carbon dioxide and other gases.

Mr Schwarzenegger reached a deal with the Democrats who control the state legislature, defying the opposition of his fellow Republicans.

He called it "a historic agreement... to combat global warming".

The bill is due to go before a vote in the state assembly and senate before the legislative session closes on Thursday before elections to be held in November.

But the measures may be too little, too late, according to the warnings of a leading US scientist.

Professor John Holdren, the president of the American Association for the Advancement of Science, told the BBC that climate change due to human influence was happening faster than predicted.

"We're already experiencing dangerous human disruption of the global climate and we're going to experience more," he said.

The measure creates a huge rift between the governor and his closest allies, the California Chamber of Commerce and some manufacturers.