When Argentina’s Jorge Mario Bergoglio was elected pope in 2013, his vision for human justice and equality was so entwined with nature that he chose the papal name Francis, honoring the patron saint of ecology. That belief, and how passionately he advocated for it, influenced the course of global climate and energy policy and in particular the 2015 Paris Agreement.
Francis’ 2015 papal letter or encyclical, Laudato Si’ ("Praise Be to You”), was the first devoted to global warming. It tied together climate science, wealth inequality, consumption (what he lamented as a "throwaway culture”) and technology in a 40,000-word missive shared with the world’s more than 1 billion Catholics. His words could be blunt: "The Earth, our home, is beginning to look more and more like an immense pile of filth,” he wrote.
He continued to speak and write on the topic, telling oil and gas executives in 2018 that transitioning to clean energy was a "duty” to humanity and denouncing climate denial in another document, Laudate Deum.
Laudato Si’ was "a major contribution to the global mobilization that resulted in the landmark Paris Agreement on climate change,” U.N. Secretary General Antonio Guterres said following Francis’s death last Monday at the age of 88. Simon Stiell, executive secretary of the U.N. group overseeing climate diplomacy, described the late pontiff as "a towering figure of human dignity, and an unflinching global champion of climate action as a vital means to deliver it.”
Released publicly in June 2015, Laudato Si’ launched Francis into what was then the world’s most pressing climate debate. With nearly 200 nations due in Paris that fall to negotiate a critical pact on greenhouse gas pollution, the first pope from the Global South harnessed his reach to push for an aggressive deal.
Laurence Tubiana, an economist and French diplomat who was president of the 2015 talks, recounted in a 2021 essay how involved Francis was with heads of state and delegations. Diplomats reached out directly to him to help try and bring Nicaragua, one of the few holdouts, into the pact. Nearly all countries agreed to an accord in December, and it became the global framework for governments, cities, companies, investors and communities to develop and deploy climate policies. (The U.S. left the Paris Agreement earlier this year.)
Oscar Soria, co-CEO of The Common Initiative, an economics and environmental think tank, first met Bergoglio as a journalist in Buenos Aires in the mid-1990s and kept up with him over the years. Soria says the pact would not exist in its final form without Francis. Its preamble addresses climate justice, intergenerational equity and the rights of Indigenous peoples — all central to Francis’s platform. That they were included despite being absent from early drafts, Soria attributes to Francis’ influence creating "moral urgency” among diplomats.
"Those elements made the Paris Agreement a moral and ethical imperative,” he said. "The Paris Agreement has a soul because he put that soul there.”
As much as he energized climate advocates inside and outside the Catholic Church, Francis’s criticism of capitalism, business and technology led conservative constituencies to balk at the political implications of his work. A study that analyzed more than 12,000 columns written by U.S. Catholic bishops found that many were either silent about climate change or distanced themselves from either the problem itself or Laudato Si’. Only a third of U.S. Catholics are familiar with the encyclical, according to a March 2024 Georgetown University survey.
Yet 32 U.S. dioceses have taken on the Laudato Si’ Action Platform, a seven-year commitment to become more sustainable. The U.S. Conference of Catholic Bishops held a session on the letter in November, for the first time since shortly after its publication, to gather ideas to mark its 10th anniversary this year.
Laudato Si’ Movement, a U.S.-based nonprofit that operates in about 140 countries, launched as the Global Catholic Climate Movement shortly before the encyclical was published and changed its name in 2021. In the decade since its founding, the organization has trained some 20,000 people in a monthslong certification process to become local leaders.
Some critics have cast climate change "as something that divides people,” said Reba Elliott, strategy director for Laudato Si’ Movement. "At the same time, there is a big constituency of Catholics in the U.S. and beyond who see that climate change is an issue that is connected with the core teachings of the faith.”
While hospitalized for pneumonia in March, Francis wrote a message to the national conference of bishops in Brazil, which will host the 30th U.N. climate talks this fall. He lauded the group’s effort to launch a campaign before the COP30 summit starts, so that "nations and international organizations can effectively commit themselves to practices that help overcome the climate crisis.”
Those invigorated by Francis’s climate work expect his commitment will endure, whoever succeeds him.
"Ten years is the blink of an eye in church time,” Elliott said. "But a lot has been accomplished so far, and it really shows that Pope Francis was speaking a message that many people want to hear and many people have responded to.”
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