Most of Australia's coal reserves will have to be left unburned if the world is to avoid catastrophic global warming, according to a major new report from the federal government's Climate Commission.
The report puts the key science advisory body on a collision course with some of the nation's biggest export industries, and marks the first time a government agency has endorsed calls for fossil fuel industries to be phased out because of their contribution to climate change.
Its findings mean that most of Australia's known coal, oil and gas reserves – many of which are already subject to minerals production licences held by companies such as BHP Billiton and Rio Tinto – must somehow be left alone if the world is to avoid dangerous climate change.
The Climate Commission acknowledged its conclusions were "sobering" and that the potential for economic disruption could be serious, but said there was no alternative if the world was to avoid dangerous climate change.
The Critical Decade 2013 – Climate change science, risks and responses, to be released on Monday.
"It isn't our job to reconcile the politics of this with the science," she said. "We are simply presenting the facts as best we know them. Just because the facts may be unpalatable to some people doesn't make them any less important."
Australia's fossil fuel resources are the equivalent of about 51 billion tonnes of greenhouse gases, about one twelfth of the world's entire "carbon budget" of about 600 billion tonnes – the amount of carbon that scientists estimate can be burned by 2050 if the world is to stop temperatures rising more than two degrees.
If that carbon budget is exceeded, the build-up of heat-trapping gases in the atmosphere is likely to trigger dangerous global warming of up to five degrees this century, the report said.
And the world is still eating into its budget far too fast, with average global emissions still rising at about 3 per cent a year, the report said.
"If emissions could somehow peak in 2015, just two years away, the maximum rate of emission reductions thereafter would be 5.3 per cent, a very daunting task," it said.
"However, if we allow emissions to continue to rise through the rest of this decade and don't reach the peaking year until 2020, the maximum rate of emission reductions thereafter is 9 per cent, a virtually impossible task unless economies around the world prioritise emission reductions above all other economic and technological goals."
Climate Change Minister Greg Combet said the government's carbon price had already driven coal use down 7 per cent, and most countries that bought Australian fossil fuels would soon have similar carbon prices.
Countries are responsible for the carbon emissions generated within their borders, a spokesman for Mr Combet said.
"When it comes to exports, the majority of Australia's coal exports go to Japan, South Korea, China and the European Union," he said.
"All these countries have introduced, or plan to introduce, a price on carbon through emissions trading schemes or carbon taxes that will apply to coal consumption."
A spokeswoman for opposition climate spokesman Greg Hunt said he would "consider the report carefully but we do not support shutting down Australia's major export industry".
If elected to government at the September poll, the opposition has pledged to abolish the Climate Commission.
"The Coalition has been consistent in arguing that the role of the Climate Commission on providing advice on addressing climate change is best undertaken by a merged department of environment and climate change," Mr Hunt's spokeswoman said. "There needs to be a continued focus on reducing emissions as is outlined in this report."
The opposition plans to abolish the carbon price and replace it with a suite of measures it calls "direct action", involving paying industries to reduce their emissions.
Both of the main parties have committed to reducing Australia's emissions to 5 per cent below their 2000 levels by the year 2020 – a target that now looks achievable, but which falls well short of the much deeper cuts outlined in the Climate Commission's report.
"To stay within the two degrees limit, the trend of increasing global emissions must be slowed and halted in the next few years and emissions must be trending downwards by 2020 at the latest," the report said. "Investments in and installations of renewable energy must therefore increase rapidly. And, critically, most of the known fossil fuel reserves must remain in the ground."