As parts of south-east Queensland and northern NSW remain under water following days of pounding rain, the UN Intergovernmental Panel on Climate Change has released a new report which says heavy rain events risk becoming more common in Australia amid rising global temperatures.

The report, published late on Monday night, provides the most comprehensive scientific assessment of the far-reaching consequences of climate change in Australia and around the world.

The panel has warned the world faces "unavoidable multiple climate hazards over the next two decades" if temperatures rise 1.5 degrees above pre-industrial levels - a threshold the planet is on track to far exceed, despite the promises made at last year's UN summit in Glasgow.

The risks only grow as temperatures rise, with predictions that almost half of the Earth's species could become extinct if global warming reaches 5 degrees.

"The scientific evidence is unequivocal: climate change is a threat to human wellbeing and the health of the planet," one of the panel's co-chairs, Hans-Otto Portner, said.

"Any further delay in concerted global action will miss a brief and rapidly closing window to secure a liveable future."

The panel said that in order to avoid a mounting human and ecological toll, urgent and ambitious action was needed to slash greenhouse gas emissions while at the same time adapting societies to live with a changing climate.

The report features a chapter on Australia and New Zealand, and highlights nine climate-related risks the region will face as the planet warmed.

This included the risk of more heat-related deaths of humans and wildlife, the loss of coral reefs and a decline in agricultural production in drought-affected parts of southern and eastern Australia.

More extreme "fire weather" was projected across the same areas, while episodes of heavy rainfall were also expected to increase.

In a briefing with reporters ahead of the report's public release, ANU professor and report co-author Mark Howden agreed that the east coast floods were the type of extreme events which would become more frequent as the planet continued to warm.

Professor Howden said the weather pattern behind the flood emergency, the La Nina phenomenon, would grow stronger in the future as global temperatures rose.

"Even though the frequency may not change, the strength of them will change. And that will increase the variability of climate in Australia, particularly in the north-east and down through the south-east," he said.

Griffith University professor Brendan Mackey, who helped write the chapter on Australia and New Zealand, said the nine climate risks which threatened the region would be more significant if warming reached 2 degrees.

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Striking agreement on a path to limiting temperature rise to 1.5 degrees was the main aim of last year's COP26 summit, which was promoted as a "last-chance saloon" to tackle climate change.

But despite many countries making fresh pledges to cut pollution, and leadership from powerhouses the US and UK, emissions projections still have the planet on a path to exceeding 2 degrees of warming.

Professor Howden anticipated carbon dioxide emissions would reach record levels this year as economies emerged from the COVID-19 pandemic, flying in the face of the urgent calls for action to slash emissions which surrounded the UN summit.

"We're not on track to even do what governments said they would do, let alone [the fact that] what government said they would do is [not] adequate to actually keep climate change down to manageable levels," he said.

The report also found that while limiting global warming to around 1.5 degrees would substantially reduce climate-related damage, it wouldn't eliminate them all.

The report's release came as new figures showed Australia's emissions had fallen by 0.8 per cent in the 12 months to September.

That means emissions are just under 20 per cent below 2005 levels, still on track to meet the Coalition's Tony Abbott-era target of cutting pollution by 26 to 28 per cent this decade.

The Morrison government believes emissions could fall up to 35 per cent if its stretch targets for the development of low-emissions technologies, such as hydrogen, are met.

A statement from Energy Minister Angus Taylor noted that the drop in emissions came as the Australian economy grew by 3.9 per cent over the same period.

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