Pope Francis called on humanity to hear “the increasingly desperate cries of the earth” Friday, insisting that immediate action is needed to save the planet from being reduced to “rubble.”

Speaking in the Vatican to participants at the international conference “Saving our Common Home and the Future of Life on Earth” in commemoration of the third anniversary of his encyclical letter on the environment “Laudato sí,” the pope stressed the “urgent need” for an “ecological conversion” as well as “concrete steps to save the planet.”

Our planet “needs urgently to be repaired and secured for a sustainable future,” the pontiff warned, without going into details.

Reiterating previous calls to action, Francis asserted that today “the pace of consumption, waste and environmental change has so stretched the planet’s capacity that our contemporary lifestyle, unsustainable as it is, can only precipitate catastrophes, such as those which even now periodically occur in different areas of the world.”

“There is a real danger that we will leave future generations only rubble, deserts and refuse,” he said, and “the effects of the present imbalance can only be reduced by our decisive action, here and now.”

On the practical level, the pope urged nations to “honor the commitments made in Paris, in order to avoid the worst consequences of the climate crisis,” referring to the COP21 Paris climate accord and its call for dramatic reduction in emission of greenhouse gases.

He also gave a plug for the next such conference, the COP24 Summit, to be held in Katowice, Poland, in December, which he said “could prove a milestone on the path set out by the 2015 Paris Agreement.”

Along with the COP meetings, Francis noted the Global Climate Action Summit, to be held from 12-14 September in San Francisco, which he trusts “will provide suitable responses, with the support of citizens’ pressure groups worldwide.”

Religions, and the Christian Churches in particular, “have a key role to play” in the fight for the planet, Francis said, holding up the “Day of Prayer for Creation” as an especially apt Christian response to the climate crisis.

Present circumstances require “radical change,” the pontiff said, if humanity is to win the battle for the planet.

Some Catholic prelates, while endorsing the pope’s message on responsible stewardship of creation, have distanced themselves from the more political aspects of climate change activism, insisting that Christian doctrine supports the former while leaving the latter open for honest debate.

Bishop Thomas J. Tobin of the Diocese of Providence, for instance, said last month that one can “support the faith-filled vision of ‘Laudato Si’ without necessarily endorsing the Paris Climate Accord,” since the first “is a comprehensive statement of faith; the second a political agreement.”

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