Tony Abbott's claim that carbon dioxide may not be the villain it's been made out to be is not inconsistent with the opposition leader's previous acceptance of climate science, a senior Liberal says.
Mr Abbott on Monday told a community forum in Perth that the science wasn't settled yet.
"Whether carbon dioxide is quite the environmental villain that some people make it out to be is not yet proven," he said.
On Tuesday, opposition frontbencher George Brandis denied his leader's comments were at odds with previous statements that he accepted the science of climate change.
"I thought what he said was perfectly unexceptionable," Senator Brandis told Sky News.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
"The fact is that science is never absolutely settled."
What Mr Abbott said was "completely consistent" with the coalition's position that the consensus of the majority of scientific opinion was that climate change was a reality and human activity contributed to it.
But Labor minister Craig Emerson said the comments proved Mr Abbott had only being saying the science was settled because it was convenient to do so.
"Now he's questioning the most fundamental aspect of the climate change science as to whether carbon dioxide is actually the cause of human induced climate change," Dr Emerson told Sky News.
"Well it is. It is the issue. That's why we are putting a price on carbon."
Dr Emerson also endorsed Prime Minister Julia Gillard's frank admission on Monday night that she had walked away from her election promise not to introduce a carbon tax.
Ms Gillard said on ABC TV: "I did say during the last election campaign, I promised that there would be no carbon tax. That's true and I've walked away from that commitment and I'm not going to try and pretend anything else."
Dr Emerson said the prime minister had previously made the point she was forced to change tack due to the composition of the parliament after the August 21 poll.
But Senator Brandis said Ms Gillard had finallycome clean.
"The Labor party is trying to make a virtue of the prime minister's frankness about this," he said.
"Well you know guilty pleas are always frank.
"What the prime minister did last night was she pleaded guilty to misleading the Australian people and walking away from a promise."
Ms Gillard had verified that she was paying the price for her alliance with the Greens, Senator Brandis said.
