Pope Francis is pushing the world’s 1.3 billion Catholics toward climate action—and looking to communities outside traditional centers of power to lead the way.

It’s hard to really “get” the Amazon if you’re not from there, according to Indigenous leader Patricia Gualinga. But she says that Pope Francis—despite all the miles that separate the Vatican from the world’s most famous rainforest—understands it in a profound way.

A leader from the Kichwa community of Sarayaku in Ecuador, Gualinga has put her life on the line to advocate for the rights of Indigenous people in the Amazon. If anyone has a right to call out the church for the ways it has historically failed to stand against or even been complicit with destructive projects of extraction and colonization that threaten life in the Amazon, it’s her.

But when asked about it, Gualinga is more likely to highlight the church’s recent championing of the region than anything else. She credits this shift largely to Pope Francis, formerly known as Jorge Mario Bergoglio, who assumed the papacy in 2013.

“The changes have been felt since the moment the pope chose the name ‘Francis,’ who within the Catholic faith is a saint who loved all creation as a work of God. [Saint Francis] spoke with nature, understood Brother Wind and Sister Rain, and had this connection to communicate with them just like our Indigenous wise men and women,” she says. “At that moment, without knowing him, I knew there would be good surprises.”

The first of those “good surprises” came in the form of Laudato Si’, an encyclical (an important church document that communicates something the Pope considers a high priority) on the environment. Laudato Si’ poetically weaves together theology, economics, and science to urge the church to take action on issues like climate change and overconsumption. Released in 2015, Laudato Si’ was the first encyclical out of the 240 that had been written since 1854 to focus solely on the environment.

Activist and writer Bill McKibben has called Laudato Si’ “the most important document about climate change in the past decade.” It’s not hard to see why: about one seventh of the world’s population identifies as Catholic and the Church owns 8 percent of land worldwide. Anything that could influence all those people to more actively work towards environmental justice would be significant indeed.

We have to realize that a true ecological approach always becomes a social approach. It must integrate questions of justice in debates on the environment, so as to hear both the cry of the earth and the cry of the poor.

According to Jesuit Father Rigobert Minani Bihuzo, the impact of the encyclical over the past five years has been “tremendous.” Hailing from the Democratic Republic of the Congo, Minani Bihuzo’s Catholicism has long been influenced by a uniquely African spirituality that he describes as “linked to the trees, the water and the moon.” But it wasn’t until Laudato Si’ was released that he saw care for the environment move into global church teachings in a significant way.

Pope Francis was far from the first pope to write or speak about the environment, Minani Bihuzo says. But the fact that he started from science, rather than sticking just to theology, is part of what differentiates him from his predecessors. It’s also what made his encyclical powerful even in the political sphere, read and referenced by Catholic leaders like U.S. President Joe Biden in addition to leaders who profess no faith at all.

“I was in France during COP25,” remembers Minani Bihuzo. “Normally, France is very proud to say they are a secular country, but the minister of the environment at that time and the president himself—all of them were quoting Pope Francis. I would not have imagined the impact [of the encyclical] would be at that scale.”

Embedded in Laudato Si’ is the idea of the interconnectedness of all things, a concept Pope Francis refers to as “integral ecology.” The document highlights in particular the idea that poverty and climate change are two expressions of the same crisis.

“We have to realize that a true ecological approach always becomes a social approach,” Pope Francis wrote in the encyclical. “It must integrate questions of justice in debates on the environment, so as to hear both the cry of the earth and the cry of the poor.”

To Father Peter Hughes, an Irish Catholic priest who’s been living in Peru for over 50 years, this means that a mandate to address environmental degradation goes to the very heart of the Christian message. Hughes subscribes to an idea from Latin American liberation theology that describes God as having a “preferential option for the poor,” meaning that, though God loves everyone, “the poor are the preferred ones of the Lord of life.” To link their plight with that of the Earth communicates that the Earth has a “preferred” place in God’s priorities, as well.