An Australian report also warned the world was warming faster than predicted, with harmful emissions exceeding worst-case estimates.

Already known as the world's biggest emitter per capita, Australia is ranked seventh among countries with the highest-emitting power sectors, according to the Centre for Global Development.

The nation's energy industry produces 226 million tonnes of carbon dioxide a year, ahead of South Africa, Britain and South Korea. The list is led by the United States with 2.79 billion tonnes, followed by China.

At the Munmorah power station near Newcastle, 15 Greenpeace activists were arrested after chaining themselves to the plant and painting "coal kills" slogans.

Protester Stephen Campbell said Munmorah was one of the oldest and dirtiest in Australia.

"We have taken this action to show that this is exactly the kind of facility we need to be closing to move toward a cleaner energy future," he said.

The global warming report prepared by former head of the CSIRO's atmospheric research unit, Dr Graeme Pearman, found temperatures and greenhouse pollution were rising faster than forecast by the Intergovernmental Panel on Climate Change.

The report, prepared for the Climate Institute, noted the panel's Fourth Assessment Report used material up to mid-2006, but new observations had been published since.

"These suggest that the [panel] assessment is under-estimating the risks of adverse impacts due to increased warming during this century and that impacts previously considered to be at the upper end of likelihood are now more probable. Greenhouse emissions are rising faster than the worst-case ... scenarios."

The report found if current trends continued, the world's temperature would rise approximately 3 degrees by the end of this century, relative to pre-industrial temperatures well above what are considered dangerous levels.

Dr Pearman, now a private consultant, urged Australia to sign the Kyoto Protocol or be left on the sidelines at the United Nations' climate change talks in Bali next month.

He said Australia would be "sitting on the sidelines" while world leaders launched serious negotiations on a comprehensive post-2012 Kyoto agreement on fighting climate change.

Corporate research has found Australia's biggest companies are unprepared to manage the significant risks to their bottom line posed by climate change.

Firms in the utilities and energy sectors are the worst offenders, the study of the top 200 listed companies by Reputex showed.

On a scale of between minus one and one, the companies generated an average score of minus 0.08. AAP