The Coalition government is set to pay a "high political price" for its Direct Action climate change plan, according to the United Nation's climate chief.
Christiana Figueres, executive secretary of the UN Framework Convention on Climate Change, said the government's approach could be "a lot more expensive" than pricing carbon and called for rapid cuts in emissions to avoid the kind of "doom and gloom" represented by the New South Wales bushfires.
"What the new government in Australia has not done is step away from its international commitment on climate change," Figueres told CNN. "What they are struggling with is not what they are going to do but how are they going to get there.
"They are going to have to pay a very high political price and a very high financial price because the route they are choosing to take to get to the same target agreed by the last government could be a lot more expensive for them, and for the population."
The Coalition has set a fixed amount of $2.5bn over the forward estimates to pay for its Direct Action plan, which would involve incentives given to businesses to cut emissions, as well as activities such as storing carbon in soils.
Independent analysis has shown that it may have to spend billions of extra dollars in order to meet the bipartisan target of at least a 5% reduction in emissions by 2020, based on 2000 levels.
Greg Hunt, the environment minister, has indicated parts of the Direct Action plan could be implemented without legislation, due to a potentially hostile Senate that won't change until July next year.
Figueres said that she supported putting a price on carbon, echoing senior figures at the OECD, IMF and World Bank, who have all stated over the past week that carbon pricing is the most cost-efficient way of reducing emissions.
"We are already paying price of carbon," she told CNN. "We are paying the price with wildfires, we are paying the price with droughts, we are paying the price with all sorts disturbances to the hydrological cycle.
"What we need to do is put a price on carbon so we don't pay the price of carbon."
Figueres added that the world needed to take "vigorous action" to help avoid the "doom and gloom" scenario illustrated by the NSW bushfires, insisting that there needed to be zero net emissions by 2050 to avoid dangerous climate change.
"We have very little time left and we are closing the window upon ourselves," she said. "But we do have time. The trajectory of emissions is still rising so we need to get to our global peaking point this decade and then get our trajectory down."
Figueres said Australia wouldn't suddenly move to a "magical world" that doesn't have fossil fuels but that the future involved a more "balanced and healthier" energy mix.
"There will always be a base load provided by fossil fuels," she said. "The issue is, however, that those fossil fuels, coal in particular, cannot pursue business as usual. They have to invest in carbon capture and storage, they need to become much more efficient, because most of the plants are horribly inefficient, and they need to invest in the new technologies of the future."