Mr Hockey would almost certainly have become Liberal leader last November had he renounced his belief that a market mechanism was the best way to reduce carbon emissions.

After Tony Abbott won the leadership, the Coalition introduced a ''direct action'' climate plan, which uses government grants and subsidies to reduce emissions by 5 per cent by 2020 but puts no price on carbon or penalty on polluters.

Mr Abbott has said he would review the policy in 2015, leaving open the possibility he could support a carbon price if other countries did so by that time.

But clearly he was implying this was highly unlikely.

''I am saying that our proposal is a much better way forward than Mr Rudd's great big new tax,'' he said in February. ''I've said many times before that if the whole world changes, we'll change with them, but the world ain't going to change any time fast.''

Mr Hockey has reconciled his views with the new Coalition policy by pointing to debates in many other countries about the most efficient way of pricing carbon and the failure of the Copenhagen meeting to reach a legally binding agreement. He said that until a global market was meaningful and liquid there was no point in Australia proceeding with a cap and trade emissions scheme on its own.

And yesterday he repeated the Coalition's refrain that since the backflip by the Prime Minister, Kevin Rudd, who delayed his emissions trading scheme until 2013 at the earliest, the Coalition stood as the only major party with a clear policy to combat global warming.

But asked by Fairfax Media about his statement that investors in the Australian energy market needed clear market signals, Mr Hockey said that ''inevitably we'll have a price on carbon … we'll have to.''

The 46-page values document he released yesterday took a more sceptical stance.