BELEM – On Monday, Pope Leo XIV made an earnest appeal to world leaders at the United Nations climate conference, urging them to take decisive measures against climate change. He emphasized that humanity is currently falling short in addressing the crisis, stressing that nature is manifesting its distress through increased floods, droughts, storms, and relentless heatwaves.

In a video address shared with religious leaders in Belem, Pope Leo acknowledged some progress has been made but insisted it is insufficient. He highlighted the plight of those most affected, stating, “One in three people live in severe vulnerability due to climate changes. For them, climate change is an immediate threat, and ignoring their plight is a denial of our common humanity.”

The Pope’s call to action coincided with the second week of the climate talks, as senior government officials from around the globe gathered near the Brazilian Amazon to partake in discussions. Monday was marked by a series of speeches, including impassioned pleas from leaders of Global South countries who recounted the devastating impact of recent extreme weather events and natural disasters.

Nations most at risk have been advocating for greater commitment at these discussions. There is growing recognition among global leaders that surpassing the 1.5 degrees Celsius (2.7 degrees Fahrenheit) warming threshold since pre-industrial times—a target set in the landmark Paris Agreement of 2015—appears increasingly likely.

Vulnerable nations have pressed for more ambition at these talks as world leaders have begun to acknowledge that Earth will almost surely go past a hoped-for limit — 1.5 degrees Celsius (2.7 degrees Fahrenheit) in Earth’s warming since pre-industrial times. That was the target set at these talks in 2015 in the landmark Paris agreement.

Scientists say in addition to deadly heat, a warming atmosphere leads to more frequent and deadly extreme weather such as flooding, droughts, violent downpours and more powerful hurricanes.

Leo said there’s still time to stay within the Paris Agreement, but not much.

“As stewards of God’s creation, we are called to act swiftly, with faith and prophecy, to protect the gift He entrusted to us,” he said. And he added: “But we must be honest: it is not the Agreement that is failing, we are failing in our response. What is failing is the political will of some.”

Leo made history this year by becoming the first American pope, and has embraced Pope Francis’ environmental legacy, including dismissing climate skeptics.

The U.S., the world’s second-largest polluter, is skipping the conference. U.S. President Donald Trump called climate change “the greatest con job ever perpetrated on the world” during a speech to the U.N. General Assembly in September.

U.N. climate chief Simon Stiell said Leo’s words “challenge us to keep choosing hope and action.”

Leo “reminds us that the Paris Agreement is delivering progress and remains our strongest tool — but we must work together for more, and that bolder climate action is an investment in stronger and fairer economies, and more stable world,” Stiell said.

David Gibson, director of the Center on Religion and Culture at Fordham University in New York, said Leo is becoming the world’s most prominent moral leader against climate change.

“This message does stake Leo out as a voice for the rest of the world, especially the Southern Hemisphere where climate change is wreaking havoc with the vulnerable in Asia, Africa and Latin America,” said Gibson.

And he said it shows that Leo, who spent decades working as a missionary in Peru and is a naturalized Peruvian citizen, “has a Latin American heart and voice.”

The Laudato Si’ Movement, a Catholic climate movement that takes its name from a 2015 encyclical in which Pope Francis called for climate action, called Leo’s message “a profound moral intervention.”

“He reminds the world that creation is crying out and that vulnerable communities cannot be pushed aside. “His voice cuts through the noise of negotiations and calls leaders back to what truly matters: our shared humanity and the urgent duty to act with courage, compassion, and justice,” the group’s executive director, Lorna Gold, said.

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This story was produced as part of the 2025 Climate Change Media Partnership, a journalism fellowship organized by Internews’ Earth Journalism Network and the Stanley Center for Peace and Security.