The federal government has been keeping almost a year's worth of pollution data secret, despite it being scheduled for release in May, documents obtained under freedom of information laws reveal.
Independent estimates suggest Australia's greenhouse gas emissions have risen sharply since the government last released its quarterly data in December - a trend that would make the nation's commitment to cutting emissions more disruptive and expensive.
Quarterly updates by the National Greenhouse Gas Inventory, described as "up-to-date information on emissions trends for business, policymakers and the public", have been released 28 times since 2009, but not since last year.
Documents obtained under FOI by the Australian Conservation Foundation reveal that while the government possesses data on greenhouse pollution for the two quarters leading up to the end of last year, it has failed to release them.
Environment and Energy Minister Josh Frydenberg did not answer Fairfax Media's questions about the missing data.
However, a spokeswoman for the minister said the September 2016 Quarterly Update was going through "the usual clearance processes prior to publication" and that "no publication date [had] been set".
"As has always occurred in the past, the government will release the data."
The chief executive officer of ACF, Kelly O'Shanassy, said the government appeared to be going to "extreme lengths" to remove global warming entirely from the national debate.
"Hiding pollution isn't a solution to the Turnbull government's paralysis on climate change and energy policy, but it's exactly what you would do if you knew you were going to fail to meet your international commitments to reduce pollution," she said.
"We are concerned Australia is not going to meet its 2030 target to reduce emissions by 26-28 per cent."
Departmental correspondence obtained under FOI confirms advice that the data be released "from March 31" and that the team was "preparing for release of the full set of accounts late on Friday 26 May". But that did not happen.
The most recent data published by the inventory showed Australia's emissions had increased 0.8 per cent in the year to June 2016, while emissions from the electricity sector alone increased by 1.2 per cent.
"Australians deserve transparency. I think it's crystal clear the Australian government is not taking its commitment to reduce pollution seriously," Ms O'Shanassy said.
According to estimates by consultant Ndevr Environmental, Australia's overall emissions increased by 1.15 per cent in the first quarter of this year, while electricity sector emissions increased by 11 per cent.
The overall emissions increase is equivalent to an extra 2,308,846 cars on the road.
According to Ndevr Environmental, the increase is almost entirely attributable to electricity emissions, while other sectors such as transport emissions decreased over the quarter.
The environmental consultant began publishing its own estimates of Australia's greenhouse gases last year, by closely replicating the government methodology.
"We pulled apart the government's historical quarterly reports, looked at all references … and basically reverse engineered it," said Ndevr Environmental's managing director Matt Drum.
Ndevr Environmental achieved a 99.19 and 99.55 per cent accuracy rating on estimates it made for the March and June quarters of last year, after cross-referencing them with the government's results.
"When [the pollution results] are released, I'd say the government's will be very close to ours," Mr Drum said.
"With no price on carbon, no effective policy settings, I don't see anything that would cause a step change or downward push on emissions."
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