Man-made climate change poses an "immediate threat" to Australia's way of life, a major UN report has warned.

The Intergovernmental Panel on Climate Change (IPCC) released its latest major update in Japan on Monday, with claims the effects of a changing global climate are being felt across the globe.

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The UN-led IPCC report, Climate Change 2014: Impacts, Adaptation and Vulnerability was produced by 309 authors and editors from 70 countries and backed by many governments around the world.

"In many cases, we are not prepared for the climate-related risks that we already face," said Vincente Barros, co-chairman of the IPCC's Working Group II that produced the report.

The report paints an alarming portrait of the impact of climate change for Australia.

It cites rising sea levels, loss of animal habitat, increasing heatwaves and droughts as a "very real and immediate threat to Australia's society and economy".

The report said the Great Barrier Reef faces "irreparable damage" within 25 years.

"Even a one degree Celsius temperature change will bring devastating impacts," said Professor Ove Hoegh-Guldberg, a Brisbane-based marine biologist and a lead author of the IPCC report.

"Over half of the Great Barrier Reef has already disappeared in the last 27 years from ocean acidification due to carbon emissions, causing mass bleaching and death to many of its ecosystems."

Source: AFP