This past Monday, the world lost an environmental hero.

Pope Francis was more than just the esteemed leader of the Catholic Church—with a papal name based on the patron saint of ecology, he was a prominent advocate for environmental stewardship and climate change mitigation.

Over his 12 years of leadership, he reframed climate change as a spiritual issue and argued that we have a moral imperative to address it, one rooted in the sanctity of the Earth and believers’ God-given duties. He was a powerful diplomatic presence throughout the Paris Agreement negotiations, advocated for the protection of the Amazon, and even launched a solar project to power Vatican City with 100% renewable energy.

But if we had to boil his environmental legacy down to just one thing, it would have to be his groundbreaking encyclicals on climate, starting with Laudato Si’: On Care for Our Common Home.

In this powerful and lengthy letter from 2015, Pope Francis highlighted the severity of environmental degradation, the immense challenge of addressing climate change, and the importance of education, individual action, and cooperation in protecting our “common home.” He grounded this appeal not only in the Church’s principles, but in the best scientific research available at the time.

And this comprehensive, progress-oriented document on climate now forms part of the official body of the Church’s social teachings.

Eight years later, Pope Francis doubled down on his message with another encyclical letter: Laudate Deum. Here, he spoke to the immediacy of the climate crisis, the consequences of chasing technological innovation at the expense of the planet, and the inadequacy of the international community’s climate response.

And while neither encyclical single-handedly shifted public thinking around climate change, even in faith communities, both elevated and expanded the public discussion about climate change.

During Paris Agreement negotiations at COP 21, more than 10 world leaders referenced Laudato Si’ in their speeches. 32 U.S. dioceses have made public commitments to sustainability through the since-launched Laudato Si’ Action Platform. And several hundreds of Catholic institutions around the world have ceased their fossil fuel investments in the wake of the encyclical’s release—a number that only continues to grow with each passing year.

Of course, the Pope’s scathing indictment of capitalism, technology, and overconsumption didn’t win him any favors with many of his fellow bishops and conservative groups. But despite the criticism he faced, he never once shied away from his commitment to the environment.

Time and time again, he chose to use his enormous platform for good.

Let’s honor his powerful environmental legacy by continuing our advocacy.