Climate change guru Ross Garnaut says it will be "terribly hard" for Australia to kick off an emissions trading scheme (ETS) by 2010, but that delaying its start would be worse.

And he says the scheme's best chance of success, as part of the nation's role in tackling climate change, would be if it was as broad as possible, and have bipartisan backing.

Professor Garnaut, the economist advising the federal government on climate change, released his much-anticipated draft report on Friday.

He said transport fuels should be included in the ETS and raised concerns about calls for the excise on petrol to be cut, saying it would send the wrong signal.

Prof Garnaut said there was no sense in delaying the introduction of emissions trading until 2012, as suggested by the federal opposition.

"The one question you have to ask is whether it would help to delay it," he said.

"A lot of the difficulties of 2010 are going to be difficulties in the first year of the scheme. Some of these will be political difficulties - it's change.

"The sooner the structures are put in place, the sooner the process of learning and adjustment takes place."

The draft report recommends the emissions trading scheme issues permits for greenhouse gases up to limits and releases them in line with the scheme's carbon reduction trajectories.

Prof Garnaut expects there to be some resistance to the changes to be recommended in his final report due later in the year.

"Whenever a major report is introduced there is clear resistance," he said.

But Prof Garnaut said that as soon as the structures were put in place, the sooner the process of dealing with climate change could begin.

He was also critical of delays under the previous coalition government.

"Can we do that (introduce a scheme) by 2010? Well, it would have been better to start half a dozen years ago, no doubt about that," he said.

"Now is not the best time to start. That best time was years ago and there were proposals before the Australian cabinet years (ago) to make that start. But that's water under the bridge."

Prof Garnaut said a 2010 start for emissions trading would be "terribly hard", but possible.

"That is the basis on which I am working," he said.

His draft report is the culmination of one year's intensive research, analysis, modelling and consultation to better define the implications of climate change for Australia, and the most effective policy options at the country's disposal.

It is the first of three steps in releasing the Garnaut Review's perspective on climate change policy options, including the early findings of economic modelling work.

Prof Garnaut said it was a matter for the government whether or not to adopt his recommendations.

"They'll take their decisions on that. They've already taken their decisions, they'll take a lot more," he said.

"I think there are ways of managing these matters that could be substantial political pluses, especially given the Australian community's interest in the matter."

Prof Garnaut will be hosting public forums in cities around Australia in early to mid-July to discuss the draft report.