"You had a step down in the emission intensity in power stations from the carbon price – and now you have a step back up," Professor Jotzo said. Climate change politics are likely to heat up in coming weeks as the government holds its first auction under its Direct Action plan to pay polluters to cut emissions, and it takes submissions for the reduction goals Australia should set for post-2020 ahead of a global summit in Paris in December. The government is also seeking to cut the Renewable Energy Target, arguing the power sector is oversupplied and won't need as much renewable energy as expected by the decade's end. A paper by Professor Jotzo and his ANU colleague Marianna O'Gorman last year calculated the carbon price had triggered a reduction in emissions in the power sector – which accounts for about one-third of the country's total – of between 11 and 17 million tonnes in the National Electricity Market (NEM) during the two years. The authors estimated fossil fuel power plants with 4.4 gigawatts of capacity were been taken offline during the carbon tax years. About one third of that total, or 1.5 gigawatts, had since been switched back on, Professor Jotzo said on Monday. The rise in emissions intensity of the NEM have also been tracked by energy consultants, Pitt & Sherry in their monthly Cedex reports. In February, for instance, emissions from the main grid rose at an annualised rate of 4.1 million tonnes compared with last June. The trend is likely to quicken as cheap gas gets diverted to export markets in coming months, lifting coal's share even further, according to principal consultant, Hugh Saddler.

Drop slows The country's overall emissions trajectory is also showing a slowdown in its decline since the end of the carbon price. All up, emissions for the 12 months to September totalled 535.9 million tonnes, the government data shows, 0.6 per cent lower than a year earlier. By contrast, emissions in the year to June were 542.6 million tonnes, a 1.4 per cent annual reduction, the data shows. "From all the reports we have seen in the last 12 months, Labor's climate policies worked to bring down emissions in the electricity sector," Mark Butler, Labor's shadow minister for climate change, said. Environment Minister Greg Hunt last week trumpeted signs of a slowdown in emissions growth from electricity and other sectors of the economy to claim Australia would comfortably achieve the bipartisan goal of cutting greenhouse gas levels by 5 per cent of 2000 levels by 2020.

Lowering projections from sectors such as agriculture – combined with 129 million tonnes of carbon credits from over-achieving during the first period of the Kyoto Protocol – mean Australia's cumulative abatement requirement for the 2013-2020 years had shrunk to 236 million tonnes, Mr Hunt said last week. "Labor always said we'd never achieve our targets. We will," a spokesman for Mr Hunt said. "We'll achieve our targets without a carbon tax." The Climate Change Authority, though, said on Monday that most of the work had been done prior to the Abbott government taking power, notably the credits gained by land clearing turning out to be less than expected for the first Kyoto period running 2008-2012. "We calculate that the carry-over that Australia has is equivalent to four percentage points of the 2020 target," Kath Rowley, general manager for reviews at the authority, said on Monday. "The effective target, once you account for carry-over (credits), is 1 per cent."

Carbon crunch Interestingly, the official 2012-13 greenhouse gas projections – released soon after the Abbott government took office – estimated the cumulative emissions reduction from the carbon tax and the smaller carbon farming initiative was about 39 million tonnes, out to 2020. In the 2014-15 projections released by the government last week, the estimated impact from the carbon price had shrunk to just 12 million tonnes. However, analysts say that tally undercounts the full effect by omitting how much higher emissions would have been without a carbon price. It also ignores the on-going emissions avoided because of investments in energy efficiency, solar panels and other low-carbon activities prompted by the tax. "Tricky accounting won't protect Australia's agricultural land from more intense fires, floods and droughts," Greens leader Christine Milne said.

"It's no wonder the National Greenhouse Accounts are released so quietly every quarter," Senator Milne said. "The Abbott government made it free for polluters to pollute. What did they think was going to happen? "Emissions are going back up and undoing all the good that was achieved with the carbon price, which made the polluters pay," Senator Milne said. With Lisa Cox