Prof Garnaut has largely endorsed changes to the scheme, currently the subject of a Senate inquiry.

However, he remains critical of some parts of the scheme, including assistance for trade-exposed industries.

In relation to trade exposed industries, the legislation does have some characteristics "that I would consider to be less than ideal" he told the inquiry in Canberra on Friday.

"I think the most important thing is that we make it clear that we are going to get rid of the system of assistance for trade exposed industries, when the rationale for it disappears."

And that would happen either when comparable emissions constraints were in place "in a large part" of the rest of the world, he said.

Prof Garnaut said there were three significant steps that would need to be taken to make the emissions trading scheme beneficial.

The first of those measures was to put back on the table the condition of 25 per cent reduction in emissions by 2020, he said.

"The government's done that and my assessment is that it now would be clearly a positive for this bill to be passed into law."

But Prof Garnaut dismissed concerns raised by the Minerals Council of Australia which suggested the government's minimum target of reducing emissions by five per cent of 2000 levels would cost 24,000 mining jobs over the next 10 years.

He did not believe an emissions trading scheme would mean fewer jobs.

"There's no reason to think that a regime of ambitious emissions reduction will lead to a net fall in jobs," he said