In addition to being the spiritual leader of about 1.4 billion Catholics, Pope Francis advocated for taking action on climate change. That's not surprising for a pontiff who was the first to take the name of St. Francis of Assisi, the patron saint of animals and ecology.
Over his 12 years as the head of the Catholic Church, Francis repeatedly raised the problem of human-caused global heating from burning fossil fuels and he encouraged people—including world leaders—to do something about it.
His 2015 encyclical brought an influential voice into the global discussion, just as leaders were finalizing an important agreement in Paris, which aimed to address the problem. And as humans continued to heat the planet with pollution from fossil fuels, Francis' missives became progressively more urgent. Researchers felt these writings boosted Francis' prominence as a climate advocate, though they appear to have largely failed to change people's minds about climate change. Still supporters say he brought together science, morality and faith in new ways for his church.
"It was the first encyclical of its kind to look at the relationship between humans and God, as well as humans and the natural world, and to link these types of relationship as matters of faith," says Christiana Zenner, associate professor of theology, science and ethics at Fordham University.
And he did that in ways that prompted people across the globe to pay attention to what is happening as the planet continues to heat up.
'Laudato si' launches a global Catholic climate movement
Environmental protection was a consistent theme in Francis' papacy and he often combined that with calls to protect the most vulnerable people. In his inaugural 2013 homily he discussed what it meant to be a protector, "It means respecting each of God's creatures and respecting the environment in which we live."
In 2015 Pope Francis issued a papal letter—or encyclical —titled Laudato Si'. It recognized climate change as a global problem with significant consequences, especially for the poor. He criticized developed countries, like the United States and China, which have contributed the most planet-heating pollution. Francis reserved his most severe criticism for the "wealthier sectors of society, where the habit of wasting and discarding has reached unprecedented levels."
In one particularly blunt section, he criticized accumulating pollution that is "non-biodegradable, highly toxic and radioactive" and said, "The earth, our home, is beginning to look more and more like an immense pile of filth."
Francis said poorer nations, which have contributed the least to climate pollution, should get help from developed countries "to support policies and programmes of sustainable development."
That echoes a major element of the Paris Agreement, which then-President Obama and other world leaders agreed to later that year. Under the climate accord, developed countries help developing countries pay the costs of building their economies with resources that won't heat up the planet even more.
Francis' climate encyclical inspired several Catholic climate groups to form, including The Global Catholic Climate Movement, which is now called the Laudato Si' Movement.
"All around the world, you saw all of these people reading the encyclical, writing letters to the editor, posting on social media, forming discussion groups in their parishes," says Rebecca Elliott, senior director for strategy and special projects at Laudato Si' Movement.
The nonprofit group says it has worked in 140 countries and trained about 20,000 community leaders it calls "animators," people who put into practice the ideas Francis has advocated. "They're educating the next generation in care for creation. They're planting trees. They're holding litter cleanups. They're doing mobilizations and marches to advocate for better policies," Elliott says.
Elliott says the pope's climate encyclical had ripple effects across the globe, including Latin America. Francis was born Jorge Mario Bergoglio in Argentina and is the first pope from the Americas and the southern hemisphere.
Elliott credits Francis' climate advocacy in getting Catholic bishops to campaign to pass a 2023 referendum in Ecuador that blocked oil drilling in Yasuní National Park, an Amazon rainforest designated a UNESCO Biosphere Reserve in 1989.
"The Catholic Church stood alongside Indigenous leaders, young people and others to support the referendum to stop oil extraction in Yasuni National Park," Elliott says.
Now, in Brazil, she says, bishops are teaching "people in every parish of the country about integral ecology," a key concept in the 2015 encyclical, that everything is connected. The United Nations will hold its annual climate conference in Belém, Pará in Brazil in November.
The Archdiocese of Chicago announced on Francis' birthday in 2023 that it would shift to all renewable energy at hundreds of buildings. Around the world, more than 8,000 families, schools, groups, dioceses and other organizations have pledged to take actions in response to Francis' climate encyclical, according to the Laudato Si' Action Platform.
Francis' climate message became increasingly urgent
As scientists warned that human-caused climate change is disrupting nature and hurting people, Pope Francis matched that urgency in his own messages.
In a 2021 BBC broadcast, before the U.N. climate meeting in Glasgow, Scotland, Francis mentioned climate change in a list of crises that included the COVID-19 pandemic and economic difficulties. As NPR reported, "the pope called on the U.N. to take 'radical decisions' to safeguard the environment and to place global concerns over the interests of individual nations."
In 2023 he also revisited the topic of climate change with another major papal document Laudate Deum, which is about one-fifth the length of his more than 38,000-word Laudato Si', and it focused directly on climate change.
"He is evidently annoyed that much of humanity seems to have missed the message," Zenner, the Fordham professor, says.
Francis addresses this "climate crisis" message to "my brothers and sisters of our suffering planet" and says "with the passage of time, I have realized that our responses have not been adequate, while the world in which we live is collapsing and may be nearing the breaking point."
"He does seem crankier," Zenner says, comparing the 2023 missive to Francis' first climate encyclical. "I think that's something that people respond to in Pope Francis as well — is that he's emotional in a very humanly relatable way."
Zenner says Francis' climate advocacy will likely endure because he was focused on changing hearts, as well as minds.
"I think that the Catholic Church now has to be seen as an entity that is concerned about care for creation and people's faith lives together. I don't think that can be erased," says Zenner.
Preaching to the converted
In the wake of Francis' 2015 encyclical, researchers wondered if there would be a "Francis effect" on Americans' views on climate change. Early research showed more Americans said they were worried about climate change than before the pope's letter, but later research found that change was short lived and affected by a person's political views.
There also were expectations that Pope Francis expressing his views on climate change could be a "turning point" and might encourage skeptics to reconsider their positions. In 2017 Francis gave a copy of his 2015 climate encyclical to President Trump, who visited him at the Vatican during his first term. Senate Minority Leader Chuck Schumer, D-N.Y., expressed hope that if Trump read the document, it would change his mind on withdrawing from the Paris Agreement.
It didn't. The next week, Trump announced the U.S. would withdraw, saying, "The agreement is a massive redistribution of United States' wealth to other countries." Now Trump is once again withdrawing the U.S.
After Francis' 2015 encyclical, researchers examined a broad range of views, well beyond the President.
"What we found was that the pope did not change people's minds about climate change. The pope changed people's minds about himself," says Asheley Landrum, associate professor of science communication and media psychology at Arizona State University.
Landrum's research shows that political conservatives responded less favorably than liberals to the pope's message. She says the problem may be that Francis was preaching to the converted and ignoring the kinds of messages a conservative audience would be more likely to accept.
"You have to think about the values and the beliefs and the concerns that your audience has and tell them why your message is consistent with those values and concerns," Landrum says. Instead, the pope mixed discussion of climate change with his criticism of wealthy countries and people "making himself look like an outgroup member to people like Donald Trump and to Rick Santorum and to Jeb Bush and other politically conservative Catholics who really did just reject his message at the time."
Landrum says Francis likely will be remembered as an "advocate for climate change" and as "an environmental pope." While he may not have changed many conservative minds, she says, "I think that he did plant a flag, and to say that climate change mitigation is consistent with socially conservative values and with Catholic values."
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