The Senate postponed last week debate on the scheme until the August sittings, although until yesterday the Opposition had been pushing to delay a vote on the legislation until after the Copenhagen international climate change conference in December.

Mr Turnbull said yesterday the Opposition was using Parliament's winter break to get Frontier Economics to ''do a very detailed study of the economic impacts, both sectorally and regionally, of the Rudd Government's design, and compare it against different variations, different approaches''.

''Given that [Prime Minister Kevin] Rudd is not prepared to do the sensible thing and postpone the completion of the scheme until next year, after the Americans have finalised their position enough in Copenhagen, it will enable us to come back with amendments that we would propose to the legislation,'' he said. Mr Turnbull pointed to previous criticisms of the Government's proposal, including its treatment of coal, as possible changes the Opposition would seek.

''Coal should be treated like every other emissions-intensive trade-exposed industry,'' he said.

''The fact that they don't take into account biological carbon offsets you know, soil carbon, biochar and those sorts of things.

''Those things aren't taken into account.

''There's a range of criticisms that we've made, but we will be able to present amendments and hopefully the Government will accept them.

''If the Government doesn't accept them, then, of course, we'll have to work out what happens next.''

Opposition frontbencher Tony Abbot said the Coalition would not support a scheme that cost jobs ''without providing any definite and guaranteed environmental benefit''.

Comments from Australian Climate Change Minister Penny Wong in today's Canberra Times