Like his predecessor Pope Francis, Pope Leo XIV has a vocal, defining focus on environmental stewardship — and he carried Francis' legacy forward on Wednesday with the Catholic Church's first-ever "green" Papal Mass.

In 2015, Francis published a groundbreaking papal encyclical, Laudato Si', and his direct, unflinching approach to climate stewardship established a now-thriving movement within the Church. 

Papal encyclicals are not solely a formal letter from a pope — they're influential directives intended to guide Bishops and the Catholic world at large on matters of morality and worship, and they "carry significant doctrinal weight."

Laudato Si' emerged to such fanfare it crashed the Vatican's website upon its release. Francis' 184-page manifesto officially declared the air pollution causing climate change a moral and spiritual crisis, calling upon Catholics to eschew overconsumption and to understand that "we are [all] part of nature."

"Living our vocation to be protectors of God's handiwork is essential to a life of virtue; it is not an optional or a secondary aspect of our Christian experience," he taught. Francis' lament led to sustained, direct action among Catholics, influencing the culture of the Church and his legacy.

Last November, Leo — then known as Cardinal Robert Prevost — spoke about the climate crisis in urgent terms, as an inalienable moral and spiritual duty. After Francis' passing, Pope Leo XIV was elected as his successor on May 8.

Leo "approved [a] new Mass formula" per the Associated Press, the first designated for "the care of creation." The "green Mass" format came at the request of Catholics motivated to act after Laudato Si'.

On July 10, Leo held Mass at a new Vatican ecological center on the grounds of Castel Gandolfo, the historical papal summer residence. 

"We must pray for the conversion of so many people, inside and out of the church, who still don't recognize the urgency of caring for our common home," Leo said, before discussing extreme weather. 

"We see so many natural disasters in the world, nearly every day and in so many countries, that are in part caused by the excesses of being human, with our lifestyle." The Pope also likened the location of the outdoor Mass to "a natural cathedral."

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According to Euronews, Leo's years of ministry in Peru informed his commitment to climate justice for Indigenous peoples in particular, which he addressed in a message released ahead of Wednesday's Mass.

"On all sides, injustice, violations of international law and the rights of peoples, grave inequalities and the greed that fuels them are spawning deforestation, pollution and the loss of biodiversity," he wrote.

Pope Francis' commitment to climate stewardship manifested in changes to the Vatican, including a fleet of electric cars and ambitious plans to transition the city-state to 100% solar energy. 

Leo plans to move ahead with Francis' plans to erect a solar farm, which would grant Vatican City the honor of being "the world's first carbon-neutral state."

During a June visit to the site, Pope Leo XIV recalled Francis' vision. The solar project "sets a very important example: we are all aware of the effects of climate change, and we really need to take care of the whole of creation, as Pope Francis has taught so clearly," he reflected.

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