Former Opposition Leader Malcolm Turnbull has delivered an extraordinary attack on Tony Abbott, describing the central plank of his successor's response to climate change as "bullshit" and saying the party could not be trusted.
But Mr Abbott has refused to respond to Mr Turnbull, insisting his argument is with Prime Minister Kevin Rudd and his proposed emissions trading scheme.
Writing on his personal website, Mr Turnbull has taken aim at his successor, ridiculing Mr Abbott's plan to reduce Australia's carbon emissions via regulation and conservation measures, rather than an emissions trading scheme or carbon tax.
Mr Turnbull confirmed he will cross the floor and vote with the Government when legislation to establish the scheme is re-introduced into parliament in February.
Mr Abbott repeatedly refused to comment on Mr Turnbull's inflammatory blog post, saying only "my argument is with Kevin Rudd. The emissions tax is Kevin Rudd's policy, he needs to defend it and explain it.''
Mr Turnbull wrote that "Tony and the people who put him in his job do not want to do anything about climate change''.
"It is not possible to criticise the new Coalition policy on climate change because it does not exist. Mr Abbott apparently knows what he is against, but not what he is for.''
"You cannot cut emissions without a cost. To replace dirty coal fired power stations with cleaner gas fired ones, or renewables like wind let alone nuclear power or even coal fired power with carbon capture and storage is all going to cost money. To get farmers to change the way they manage their land, or plant trees and vegetation all costs money.''
He dismissed Mr Abbott's suggestion that emissions can be cut without a scheme in place and without a significant cost as "bullshit", and ''Moreover he knows it.''
But Mr Abbott, who has challenged Mr Rudd to a debate on climate policy, said the opposition would have a "clear, effective and economically responsible climate change policy, and that will be announced before parliament comes back in February".
Mr Abbott dismissed suggestions the Liberals, who have endured months of public infighting and had Shadow Finance spokeswoman Helen Coonan resign yesterday, were still in disarray.
Instead he turned the focus back on Mr Rudd.
"An emissions tax is ... a policy which is starting to unravel. We had the IMF the other day come out and say this is not the right way to go. Today we have had one of Australia's main unions, the tertiary education union, say this is not the way to go,'' he said.
"Plainly unions like the CFMEU are concerned about this because they know it will terribly badly damage the jobs of their members. This is Mr Rudd's problem, he needs to deal with it, particularly he needs to explain it to the Australian people.''
But Mr Turnbull's latest comments will increase speculation the former Liberal leader plans to destabilise the man who replaced him from the back bench.
Mr Turnbull wrote that many Liberals were dismayed the party is "not simply without a policy, without any prospect of having a credible policy but we are now without integrity''.
"The whole argument for an emissions trading scheme as opposed to cutting emissions via a carbon tax or simply by regulation is that it is cheaper - in other words, electricity prices will rise by less to achieve the same level of emission reductions,'' he says.
And he warned the party would be perceived as lacking integrity after negotiating business-friendly amendments to the scheme and then reneging on the deal when Mr Turnbull was deposed as leader.
Mr Turnbull's angry posting comes a week after he described Liberal senators' decision to reject the emissions trading scheme as "very disappointing''.
Mr Turnbull was replaced as Opposition Leader by Mr Abbott last week.
James Massola is a Canberra Times political reporter.
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