PM Julia Gillard said there would be a fixed price on carbon pollution , blamed for global warming, from next year before an emissions trading scheme was introduced in 2015.

"We have had a long debate about climate change in this country ," Gillard said in a rare televised address to the nation. "Most Australians now agree our climate is changing , this is caused by carbon pollution , this has harmful effects on our environment and on the economy - and the government should act."

"But we've now had the debate, 2011 is the year we decide that as a nation we want a clean energy future. Now is the time to move from words to deeds," she said.

Under the scheme to begin on July 1, 2012, 500 of Australia's top polluters will pay a fixed price, starting at Aus$23 per tonne, for their carbon dioxide emissions for the first three years. The mechanism would then shift into an emissions trading scheme, with a price set by the market . The government will set a floor price and an upper limit for the first three years to avoid price shocks.

Experts said Australia's emissions trading scheme would be the biggest and most systematic outside Europe, similar to but larger in scale than that adopted by New Zealand.

"There's nothing really systematic in the rest of our region," John Quiggin from the University of Queensland's school of economics said. "Obviously China and India are doing things of all kinds on a very large scale... so there's certainly very serious action there; but in terms of a broad-based and systematic carbon price, this is really one of the biggest moves we've seen."

The issue of a carbon tax has been hotly debated in Australia, among the world's worst per capita polluters.