Eight years ago, he published a 200-page encyclical, titled Laudato Si. 

It was a hard-hitting appeal for urgent action to address the global climate and biodiversity crisis, to arrest what he called the “unprecedented destruction of the ecosystem”. 

He also roundly rejected bare-knuckle capitalism and trickle-down economics as a “failed theory”.

His ecological plea came wrapped in a warning: “Destroy creation and creation will destroy us”. 

While it can be difficult to gauge the precise effect of such an intervention, it was timed to influence the COP15 climate conference in Paris.

Whether or not it was a coincidence, the Paris Agreement in late 2015 was the biggest breakthrough in climate diplomacy in the last two decades.

Now, Francis is back in the ring. His new encyclical, titled Laudate Deum (Praise God) pulls no punches in setting out the scale of the existential crisis we now face, while ripping into those who have stymied decisive action on the climate emergency, putting humanity in grave danger in the process.

“The world in which we live is collapsing and may be nearing the breaking point,” he stated, deploying a clarity of language rare among world leaders, but striking a similarly strident tone as that being adopted by UN secretary-general, António Guterres.

The timing of his latest intervention is an unapologetic attempt to influence the COP28 climate negotiations being hosted by the United Arab Emirates, a petro-state.

“Despite all attempts to deny, conceal, gloss over or relativize the issue, the signs of climate change are here and increasingly evident.”

He singled out the corrosive role of climate denial: “In recent years, some have chosen to deride these facts. They bring up allegedly solid scientific data, like the fact that the planet has always had, and will have, periods of cooling and warming” to misrepresent the science.

“In order to ridicule those who speak of global warming, it is pointed out that intermittent periods of extreme cold regularly occur,” Francis noted.

The 86-year-old pontiff’s grasp of scientific nuance and understanding of detail around the climate emergency would put many a newspaper editor, political correspondent or senior broadcaster to shame. 

Striking to the nub of the issue, he stated: “Regrettably, the climate crisis is not exactly a matter that interests the great economic powers, whose concern is with the greatest profit possible at minimal cost and in the shortest amount of time”.

The pope’s timing is serendipitous. The release of his encyclical coincided with news that September 2023 has been confirmed as the hottest September ever recorded, a record it now shares with June, July, and August of this year. 

Worse, the sudden spike in September temperatures, rising an unprecedented 0.5C over the previous record, has stunned even climate scientists.

University of Reading climatologist, Ed Hawkins summed up the general reaction among experts as follows: “Surprising. Astounding. Staggering. Unnerving. Bewildering. Flabbergasting. Disquieting. Gobsmacking. Shocking. Mind boggling.” 

We appear to be perilously close to a drastic shift in the Earth’s climate system or, as the pope put it, there is “the real possibility that we are approaching a critical point”, adding that while we are now unable to halt the “enormous damage we have caused, we barely have time to prevent even more tragic damage”.

While addressing climate and bio-diversity issues is often framed in technocratic terms, in reality it is in essence a moral question. 

Humans have unleashed god-like power with which to lay waste to much of the natural world, but the carnage is often hidden. 

“The ethical decadence of real power is disguised thanks to marketing and false information, useful tools of those with greater resources to employ them to shape public opinion,” Francis says.

Without a revolution in thought that re-frames humanity as a part of nature and operating within its boundaries, there is little hope of avoiding an epic global tragedy. The current dependence on techno-fixes is, he added, “a form of homicidal pragmatism”.

He noted that those who speak up for nature are derided by the powerful and “subject to ridicule by economic interests”, but they are nonetheless on the right side of history. 

He faces “dismissive and scarcely reasonable opinions, even within the Catholic Church”. 

This is certainly borne out in Ireland, where some of the most strident attacks on environmental defenders and climate activists comes from commentators and politicians who make great play of their Catholic faith, while feeling free to discard the Pope’s teachings when it conflicts with their own ideology.

The ecological crisis is an existential emergency, challenging everything it means to be human, and profoundly questioning our place in the world.

Regardless of your religious beliefs, if any, what Francis has to say has never felt more urgent.

• John Gibbons is an environmental journalist and commentator