An international warning that global warming could kill the Great Barrier Reef, within 20 years exposed the federal government's inaction on climate change, opposition leader Kevin Rudd said.

A confidential draft of a report by the Intergovernmental Panel on Climate Change (IPCC) shows that global warming will cause billions of dollars of damage to coastal areas, key ecosystems and the farming sector without massive greenhouse gas emission cuts.

The report, published in Tuesday's edition of Melbourne newspaper The Age, said coral bleaching in the reef was likely to become an annual event by 2030 because of warmer, more acidic seas.

It takes at least a decade for coral to start recovering from severe bleaching, but with average temperatures predicted to increase by about three degrees, parts of the reef could die.

Mr Rudd said Prime Minister John Howard and the federal government should have acted sooner to avoid the impending ecological disaster.

"Those threats go to the economy of Australia, they go to our environment, they go to our responsibilities as custodians of this unique asset in our natural heritage," Mr Rudd said.

"Mr Howard has had more than a decade to act on the Great Barrier Reef, and on climate change and has failed to act."

Mr Rudd said the Great Barrier Reef, was too important a national and international asset for Mr Howard to have been "missing in action" for the last decade.

"The first thing the federal government can do is recognise that climate change is real," he said.

"Mr Howard's cabinet still has in it an industry minister who only a few months ago said climate change was a pile of hogwash."

Australia should implement its own national emissions trading scheme and develop an effective renewable energy target, he said.

"We need global leadership on climate change, and instead Mr Howard follows (US President George) Bush in ignoring the Kyoto protocol and ignoring practical programs of action which will help deal with, and turn back, the challenge of climate change."