Speaking on the legislation for the emissions trading scheme in Parliament yesterday, a defiant Mr Turnbull said he would cross the floor to vote for the scheme that he had helped shape.

The Coalition under Mr Abbott has abandoned support for the ETS and announced a rival plan where businesses that choose to cut their emissions would be paid incentives out of a taxpayer-funded pool worth $11.7 billion over 10 years.

''Having the government pick projects for subsidy is a recipe for fiscal recklessness on a grand scale, and there will always be a temptation for projects to be selected for their political appeal,'' Mr Turnbull said.

''In short, having the government pay for emissions abatement, as opposed to the polluting industries themselves, is a slippery slope which can only result in higher taxes and more costly and less effective abatement of emissions.

''I say this as a member and former leader of a political party whose core values are a commitment to free markets and free enterprise.''

Mr Abbott's policy claims to reduce emissions by 5 per cent by 2020, the same target as the ETS, but Mr Turnbull said it was not enough just to support the cuts. ''You must also deliver a strong, credible policy framework that will deliver them.''

He said without a cap on emissions and a price on carbon, there would be either no new industry investment in Australia or there would be more dirty industry built ''because they are more profitable in a world where there is no price on carbon emissions''.

Mr Turnbull implied it was improper to label the ETS a tax, as the opposition was doing, because it was not designed to raise net revenue for the government. Rather, the revenue would be returned to households and businesses as compensation and transitional assistance.