Pope Francis has urged participants of the forthcoming Cop28 talks in Dubai to agree to binding policies to phase out fossil fuels.
The Pontiff said the world's transition to clean, renewable energy was not progressing fast enough.
But he said the next round of UN climate talks opening on November 30 presented an opportunity for "a change of direction”, with real commitments to moving to clean energy sources such as wind and solar.
The Pope made the comments in an update to his influential 2015 encyclical – the highest form of papal writing – in which he spoke of the need to protect the environment, face the dangers and challenges of climate change and reduce the use of fossil fuels.
The new 7,000-word document, called Laudate Deum, was published on Wednesday, on the feast day of Francis of Assisi, the patron saint of the environment.
In it, he warned some damage was “already irreversible”.
“The world in which we live is collapsing and may be nearing the breaking point,” he said.
“It is indubitable that the impact of climate change will increasingly prejudice the lives and families of many persons.”
In the text, which runs to 12 pages, the Pope expressed hope “that Cop28 will allow for a decisive acceleration of energy transition, with effective commitments subject to ongoing monitoring”.
He called for “binding forms of energy transition that meet three conditions … efficient, obligatory and readily monitored”.
Failure at Cop28, he said, “will be a great disappointment and jeopardise whatever good has been achieved thus far”.
Only a real commitment to change “can enable international politics to recover its credibility”, wrote the Pope.
He noted the UAE was a “great exporter of fossil fuels” but has also made “significant investments” in renewable energy sources.
In the text, the Pope warned against putting too much trust in technology to capture gas emissions, saying that while it was promising, it did not tackle the human causes at the root of global warming.
Addressed to “All people of good will on the climate crisis,” the text includes some highly technical sections.
“Despite all attempts to deny, conceal, gloss over or relativise the issue, the signs of climate change are here and increasingly evident,” he said.
“No one can ignore the fact that in recent years we have witnessed extreme weather phenomena, frequent periods of unusual heat, drought and other cries of protest on the part of the earth that are only a few palpable expressions of a silent disease that affects everyone,” he said.
He specifically faulted deniers and sceptics for refusing to acknowledge the speed of the current changes taking place over “one generation – not centuries or millennia”.
Saying "it is no longer possible to doubt the human - 'antropic' - origin of climate change," he took aim at those who "deride these facts," saying they use "allegedly scientific data" to show that the planet has always had periods of warming and cooling.
He added: “The rise in the sea level and the melting of glaciers can be easily perceived by an individual in his or her lifetime, and probably in a few years many populations will have to move their homes because of these facts."