This story has been updated.
By Gary Gately
Pope Leo XIV delivered an urgent appeal to world leaders Friday to “put aside selfish interests” and join together to combat climate change, warning that rising global temperatures threaten peace and endanger the lives of some of the most vulnerable people on the planet.
“Tragically, those in the most vulnerable situations are the first to suffer the devastating effects of climate change, deforestation and pollution,” Pope Leo wrote in a message to more than 140 heads of state at a United Nations climate conference in Belém, Brazil, at the edge of the Amazon rainforest.
“Caring for creation, therefore, becomes an expression of humanity and solidarity,” Pope Leo said in the message, read aloud by Vatican Secretary of State Cardinal Pietro Parolin at the 30th annual Conference of the Parties on climate change (known as COP30). “It is vital to turn words and reflections into choices and actions based on responsibility, justice and equity to achieve lasting peace by caring for creation and our neighbors.”
The leader of the 1.4 billion-member Catholic Church framed environmental stewardship as inextricably linked to peace, saying: “If you want to cultivate peace, care for creation.”
While global attention often focuses on wars and conflicts, peace is also gravely threatened “by a lack of due respect for creation, by the plundering of natural resources and by a progressive decline in the quality of life because of climate change,” Pope Leo said, calling for “international cooperation and a cohesive and forward-looking multilateralism which puts the sacredness of life, the God-given dignity of every human being, and the common good at its center.”
“In the midst of a world that is in flames, as a result of both global warming and armed conflicts, this conference should become a sign of hope,” he said. But, Leo added: “Regrettably, we observe political approaches and human behaviors that go in the opposite direction, characterized by collective selfishness, disregard for others and shortsightedness.”
For the first time in three decades, no U.S. official attended the COP summit, and President Donald J. Trump, who has repeatedly dismissed climate change as a “con job” and a “hoax,” in January withdrew the U.S. from the Paris Agreement, the legally binding 2015 accord signed by 195 countries to combat climate change. Trump had also withdrawn the U.S. from the agreement during his first term, but former President Joe Biden rejoined soon after taking office in 2020.
Leo, the first U.S.-born pope, without mentioning Trump by name, said at an October 1 conference commemorating the 10th anniversary of the late Pope Francis’s landmark environmental encyclical Laudato Si’ (“Praise Be to You”): “Some have chosen to deride the increasingly evident signs of climate change, to ridicule those who speak of global warming, and even to blame the poor for the very thing that affects them the most.”
On Friday, Pope Leo quoted Francis’s encyclical in which the first Latin American pontiff wrote: “Climate is a common good, belonging to all and meant for all. At the global level, it is a complex system linked to many of the essential conditions for human life.”
The 70-year-old Pope Leo also quoted Pope Benedict XVI’s message for World Day of Peace in 2010: “The quest for peace by people of goodwill surely would become easier if all acknowledge the indivisible relationship between God, human beings and the whole of creation.”
And Leo noted that two decades earlier in his World Peace Day message, St. John Paul II had called the “ecological crisis” a “moral issue” that “reveals the urgent moral need for a new solidarity, especially in relations among the developing nations and those that are highly industrialized.”
Leo acknowledged that the path to achieving the goals established by the Paris Agreement, in which nations agreed to slash heat-trapping greenhouse gas emissions, primarily from burning fossil fuels, “remains long and complex.”
UN Secretary-General Antonio Guterres warned world leaders at the opening of the COP30 conference Thursday that failure to limit global warming to the key benchmark of 1.5 degrees Celsius (2.7 Fahrenheit), laid out in the Paris Agreement, would represent a “moral failure and deadly negligence.”
“We can choose to lead or be led to ruin,” Guterres said, taking aim at the fossil fuel industry and world leaders who “remain captive to the fossil fuel interests, rather than protecting the public interest.”
The planet’s relentless warming trend — which has led to more extreme heatwaves, stronger storms, devastating wildfires, rising seas, droughts and widespread hunger — has shown no signs of slowing. The World Meteorological Association reported in its State of the Global Climate Update 2025 Thursday that 2025 is projected to be either the second or third warmest year on record and that the 11-year stretch from 2015 to 2025 will be the hottest period on record.
Pope Leo reiterated the Catholic Church’s position, dating to Francis’s Laudato Si’, that wealthy nations and multinational corporations, which have exploited the Earth and its most vulnerable for profit, should repay an “ecological debt” to developing countries by helping fund climate mitigation, adaptation and loss-and-damage efforts.
“May all participants in this COP30 be inspired to embrace with courage this ecological conversion in thought and actions, bearing in mind the human face of the climate crisis,” the Holy Father said.
Leo had witnessed the toll of climate change on the poor and the vulnerable, in particular, when he served for years as a longtime missionary in Peru, where he spoke out repeatedly on the moral obligation to ensure climate justice.
Ahead of the COP30 conference, Catholic bishops in Latin America, the Caribbean, Asia and Africa jointly demanded in July an end to the use of fossil fuels and called on nations to adhere to the terms of the Paris Agreement.
“I am raising a voice that is not mine alone, but that of the Amazonian peoples, of the martyrs of the land — we could say of the climate — and of the riverside, indigenous, Afro-descendant, peasant and urban communities,” Cardinal Jaime Spengler, archbishop of Porto Alegre, Brazil, and president of the Latin American and Caribbean Episcopal Council, said at a July 1 Vatican news conference where the bishops released their 34-page appeal.