Figures published online yesterday by one of the world's top authorities on greenhouse emissions shows Australia's total fossil fuel emissions jumped by 8.3 per cent from 93 million tonnes in 2004 to just over 100 million tonnes in 2005.

This includes a 12 per cent rise in carbon dioxide emissions from cement manufacture and from aviation and shipping.

These figures, calculated by the Carbon Dioxide Information Analysis Centre in the United States, conflict with Federal Government claims that national fossil fuel emissions rose by only 2 per cent over the same period.

Australia has committed to meeting a target of 108 per cent of its 1990 emissions levels about 599 million tonnes annually by 2012.

But the centre's figures suggest this cannot be achieved.

They also question the accuracy of data used by the Rudd Government to shape its response to the challenges of climate change.

Australian National University's climate law and policy centre co-director Andrew Macintosh said, ''Are the federal figures accurate? That's the million-dollar question, but it does seem a bit odd that the numbers always seem to fall our way.''

The US centre, established more than 25 years ago, includes the World Data Centre for atmospheric trace gases and provides climate change data and analysis for the US Department of Environment.

Its latest figures show global carbon dioxide emissions from fossil fuel burning have increased by 3.8 per cent, with Australia ranked as one of the world' top 10 polluters on per capita use of fossil fuels.

The director of the University of Adelaide's climate change research institute, Professor Barry Brook, said the centre's figures showed ''rhetoric about Australia being on track to meet its Kyoto target is just greenwash''.

The figures indicated Australia was ''doing nothing effective to stem its emissions'' beyond the Government's claims that land clearance had been halted.

''In terms of fuel use, [emissions are] spirally upwards at an alarming rate,'' Professor Brook said.

''The increase from 1990 levels is now tracking at 25.8 per cent based on fossil fuel usage.''

He said even a conservative projection based on the US centre's data suggested that by 2012, Australia fossil fuel emissions could be 37 per cent above 1990 levels.

Co-chairman of international climate change policy think-tank the Global Carbon Project Dr Mike Raupach said it was possible the 8.3 per cent increase was a data anomaly.

''However, it does remind us of Australia's long-term emission growth over the last two decades, which is around 2 per cent per year and is way, way too high.

''To achieve the kinds of global emissions reductions necessary to stabilise climate at safe levels, our emissions have to shrinking at several per cent per year rather than growing, and this needs to happen within a few years. Otherwise we will bequeath the next generation an impossible challenge,'' he said.

Mr Macintosh said the centre's figures showed the Rudd Government could not afford to delay urgent action on climate change until 2010, when it expects to introduce its carbon pollution reduction scheme.

A spokeswoman for federal Climate Change and Water Minister Penny Wong said the Government would not comment specifically until more was known about the US centre's data sources. Department of Climate Change estimates of fossil fuel emissions were prepared in accordance with international guidelines, published on its website and subject to international expert review.

''Our estimates were last updated in May. The estimate for emissions in Australia of carbon dioxide from fossil fuel burning for energy in 2006 was 366.4 million tonnes an increase of around 1 per cent on 2005. The emissions growth rate for 2005 over 2004 was 2 per cent,'' she said.

Greens climate change spokeswoman Christine Milne said the US figures showed Australia's emissions from coal and oil were out of control and raised concerns about whether it would be possible to avoid catastrophic, runaway climate change.

Australian Conservation Foundation climate campaigner Tony Mohr said the figures confirmed Australia's greenhouse emissions continued to head in the wrong direction.