Pope Francis warned on Wednesday the world "is collapsing" due to global warming, urging participants of the upcoming COP28 climate talks to agree to binding policies on phasing out fossil fuels.

Eight years after his landmark thesis outlined the devastation of man-made climate change, the 86-year-old pontiff published a follow-up that warned that some damage was "already irreversible."

"With the passage of time, I have realised that our responses have not been adequate, while the world in which we live is collapsing and may be nearing the breaking point," he wrote in the 12-page letter.

But he said the next round of UN climate talks opening in Dubai on November 30 "can represent a change of direction," if participants make binding agreements on moving from fossil fuels to clean energy sources such as wind and solar.

Only a real commitment to change "can enable international politics to recover its credibility," wrote the pope.

His 200-page encyclical in 2015, entitled "Laudato Si" ("Praise Be To You"), was a global call to arms to protect the Earth, and sparked debate unprecedented for a religious text, including commentaries in scientific journals.

Months later, there was a breakthrough in UN climate talks in Paris, with nearly every nation on Earth committing to limit warming to "well below" two degrees Celsius above pre-industrial levels.

But the UN warned last month the world is not on track to meet these goals, while climate monitors predict 2023 will be the hottest in human history, with the Northern Hemisphere's summer marked by heatwaves, droughts and wildfires.

In Wednesday's document, entitled "Laudate Deum" (Praise God), Francis expressed hope that the forthcoming COP28 "will allow for a decisive acceleration of energy transition, with effective commitments subject to ongoing monitoring." (AFP)