Conservationists are calling for the closure of the country's dirtiest power stations, in light of a new UN report outlining the clearest indication yet of the severe impacts of climate change.

The Intergovernmental Panel on Climate Change (IPCC) report found the effects of climate change would soon be irreversible unless emissions are cut sharply and fast.

Chief among the recommendations was that the world rapidly decarbonise its energy systems and stop burning coal by the end of the century.

But Australia's energy system is using more coal than ever.

While demand for electricity is falling, the carbon emissions from its generation have been steadily rising since June.

In the electricity market, Victoria's brown coal power stations are back on top, reaping the rewards of higher gas prices, an end to the carbon tax and the subsequent fall in hydro-electricity production.

IPCC synthesis reports' findings: In its first assessment in 1990, the IPCC said observed temperature increases were "broadly consistent with predictions of climate models, but it is also of the same magnitude as natural climate variability".

In its first assessment in 1990, the IPCC said observed temperature increases were "broadly consistent with predictions of climate models, but it is also of the same magnitude as natural climate variability". The second assessment, in 1995, said: "Results indicate that the observed trend in global mean temperature over the past 100 years is unlikely to be entirely natural in origin."

The second assessment, in 1995, said: "Results indicate that the observed trend in global mean temperature over the past 100 years is unlikely to be entirely natural in origin." In 2001, its third assessment reported: "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities."

In 2001, its third assessment reported: "There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities." By 2007, the consensus had reached "very high confidence" – at least a 90 per cent chance of being correct – in scientists' understanding of how human activities are causing warming.

By 2007, the consensus had reached "very high confidence" – at least a 90 per cent chance of being correct – in scientists' understanding of how human activities are causing warming. This fifth assessment puts that certainty at 95 per cent and noted "recent climate changes have had widespread impacts on human and natural systems". Source: IPCC

"Brown coal in particular is the winner - the most emissions-intensive form of electricity generation in Australia has gone up significantly," analyst Dr Hugh Saddler said.

"Brown coal is very cheap to dig out of the ground and put in the power station."

A year ago, La Trobe's Yallourn generator was operating at half capacity. Now, it is running full steam.

The latest figures show in four months brown coal's share of national electricity generation has risen 4 per cent to 26 per cent, while black coal's share has risen 3 per cent to 51 per cent.

Australian Conservation Foundation president Geoff Cousins said the dirtiest generators must be shut.

"We should be listing the worst polluters and focusing on the worst-polluting coal-fire power stations and closing them down," he said.

The UN's deadline for most of the world's energy to come from low-carbon sources is 2050.

But Environment Minister Greg Hunt said improved technology would allow Australia to keep burning coal.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 8 minutes 8 m IPCC report author Lesley Hughes speaks with 7.30

"Our approach has been to let the market come forward with proposals for reducing emissions. My belief is that it's possible to clean up power stations," he said.

Greens leader Christine Milne has scoffed at the idea, calling it "nonsense".

"It's a nonsense for Greg Hunt to think that with Direct Action he's got the technology ... to prop them up," she said.

Mr Sadler said current policies would continue to advantage the country's dirtiest power stations.

"This does present a very big challenge," he said.

"The increase in electricity generation is such that if it continued for a whole year it would amount to nearly a 2 per cent increase in Australia's total emissions.

"When you put it against the target of 5 per cent reduction by 2020 that does make the task considerably more difficult."