The latest Climate Commission report has warned that 80 per cent of global fossil fuel reserves will have to stay in the ground if the planet is to avoid dangerous climate change.

The paper says global emissions need to trend downward by the end of the decade to keep temperatures at a "manageable" level.

Key points: Climate Commission says 80 per cent of the world's fossil fuel reserves will have to stay in the ground to avoid dangerous climate change

Climate Commission says 80 per cent of the world's fossil fuel reserves will have to stay in the ground to avoid dangerous climate change Report says forecasts made two years ago in the first Climate Commission report have become a reality and scientific consensus has grown

Report says forecasts made two years ago in the first Climate Commission report have become a reality and scientific consensus has grown Global emissions will need to be trending downwards by the end of the decade for keep temperatures at a "manageable" level, the report says

Professor Will Steffen, a climate commissioner who co-authored the report, says reaching the goal will be a challenge, given greenhouse gas concentrations are now at the highest level on record.

"We have to get global emissions trending downward by the end of the decade to have any reasonable chance of meeting that 2 degree target. We need to make the right investment decisions," he said.

"We have to leave most of the fossil fuels in the ground and of course that has obvious implications for investment decisions this decade.

"We have to put in place a very clear pathway to a decarbonised economy in the next 30-35 years. That requires us to make smart decisions on investments now.

Numbers 'clear and simple'

Professor Steffen says the forecasts made two years ago in the Climate Commission's first major report, The Critical Decade, have become a reality and the consensus among scientists is stronger.

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"It's so important that people realise that the numbers are clear and simple," he said.

"What did we see? Convincing evidence, not only globally, but now in Australia.

"Heatwaves in Europe, heatwaves in Russia, heatwaves in the US during the last decade. Heavy rainfall, a warming climate, more evaporation from the ocean, more water vapour in the atmosphere and more rain."

Fossil fuels need to be left in the ground

Professor Lesley Hughes, who co-authored the report, says there will be catastrophic consequences for the environment if the world does not move away from fossil fuels.

"In order to achieve that goal of stabilising the climate at 2 degrees or less, we simply have to leave about 80 per cent of the world's fossil fuel reserves in the ground. We cannot afford to burn them and still have a stable and safe climate," she said.