MELBOURNE - Climate change guru Al Gore has heaped praise on Australian Prime Minister Kevin Rudd, backing his decision to push ahead with emissions trading legislation before global talks in Copenhagen.

Mr Rudd wants to push emissions trading bills through federal parliament in August - four months before the crucial climate change summit in Copenhagen.

Mr Gore said it was important for both Australia and the United States to take the lead in tackling climate change.

"One of the barriers in the Kyoto process was that the United States and Australia did not provide the kind of leadership necessary," he told reporters in Melbourne yesterday.

"Now with new leadership in both the United States and Australia our two countries are providing leadership. When that leadership is most needed is in the run up to Copenhagen, it can make a huge difference."

The former US vice-president and Nobel prize winner is in Melbourne to train 300 people from 19 countries including India and Indonesia on how to encourage leaders to address climate change.

Today he is scheduled to deliver the keynote address at the launch of new think-tank Safe Climate Australia.

Mr Gore said although it would be difficult for world leaders to reach agreement in December on a post-Kyoto climate pact he remained optimistic.

He said the Group of Eight nations' agreement on Wednesday that developed nations should cut emissions by 80 per cent by 2050 was a step in the right direction.

"Here in Australia the percentage of the Australian people who support action is just extraordinary," Mr Gore said.

"As that same dynamic plays out in countries around the world, even those who might look at the challenge ahead and say `boy this is going to be tough', I think that we're going to do it."

Mr Rudd has warned it will be a hard slog towards reaching an agreement in Copenhagen.

The federal government has been criticised by some green groups that its target to slash emissions is weak.

It has committed to a 60 per cent reduction target by 2050, with interim 2020 targets of between 5 and 25 per cent.

Asked whether the Rudd government's reduction targets went far enough, Mr Gore said people asked him the same question about legislation in the United States.

"It's not what I would have written, I would have written it as a stronger bill, but I'm realistic about what can be accomplished within the political system as it is," he said.

"I am sincerely convinced that the right way forward is to get to the maximum that the political system will allow us to accomplish and begin the change, and then, as we gain experience with it, toughen it, strengthen it, make it better based on experience as business and industry learn how to adjust."

Mr Gore said he had tremendous confidence in Mr Rudd's leadership on climate change.

He also gave the prime minister a big tick on his handling of the global recession.

"It's extraordinary the way your prime minister and your government has responded to the economic crisis in ways that have made it far, far less severe here than in practically any other country in the world," he said.

- AAP