Election of Jorge Mario Bergoglio

(CNN) -- When Jorge Mario Bergoglio was elected to lead the Catholic church in 2013, he chose the papal name Francis, after the 13th-century figure St. Francis of Assisi, known as the patron saint of ecologists and champion of the poor.

A Fierce Advocate for the Environment

It was a befitting choice. Pope Francis was the fiercest climate and environment advocate in the church's history.

Connecting Climate Change and Social Inequities

The pope spoke often about the importance of environmental stewardship in a way none of his predecessors had, connecting climate change to social inequities, going so far as to blame industry, world leaders and "irresponsible" Western lifestyles for the worsening crisis.

Landmark Encyclical: Laudato Si'

In his landmark 2015 encyclical "Laudato Si'" on the "care for our common home," Pope Francis was able to dissolve some of the long-standing tensions between the Catholic church and ecological science, eliminating room for climate denial in the church and bringing the Vatican into the world of international climate action.

A Call to Action

In the encyclical, a kind of letter addressing the world's more than 1 billion Catholics, the pontiff argued that Catholic values were aligned with climate change action. He drew points from the Bible, including the first book of Genesis, which outlines the creation of the Earth and how humans are tasked with keeping it safe and clean.

God's Gift and Human Responsibility

He argued that God gave humans the Earth to cultivate and protect, not to conquer and destroy, underscoring how the planet had suffered from human activities since it began rapidly burning fossil fuels to industrialize. "Never have we hurt and mistreated our common home as we have in the last 200 years," he wrote.

Addressing Environmental Woes

The pope touched on a series of woes wreaking havoc on the planet: polluted air, water poverty, toxic waste, industrial pollution, rising sea levels and extreme weather.

The Impact of Timing

"The Earth, our home, is beginning to look more and more like an immense pile of filth," he wrote, using frank language. "In many parts of the planet, the elderly lament that once beautiful landscapes are now covered with rubbish."

Influence on Climate Agreements

The timing was crucial and intentional. Pope Francis pushed the Vatican to publish the encyclical early, so that it would play into the UN COP21 climate summit in Paris later that year. The pope was seen as highly influential in the landmark agreement eventually reached.

A New Paradigm in Papal Advocacy

Although popes in the past had addressed issues like environmental destruction, Alberto Pallecchi, head of faith and sustainability at the non-profit World Resources Institute, told CNN that Pope Francis' attention to climate change and the environment was "unprecedented for a pontiff," with "its significance and reach unparalleled to any faith leader."

Pushing the Agenda

"He has consistently put his moral authority on the line, pushing governments, the private sector, and rallying the global environmental faith-based movement," Pallecchi said, in an interview conducted before Francis' death.

Vatican's Role in Global Climate Framework

He put "climate change firmly on the Catholic Church agenda," he added.

Continued Advocacy

In 2022, Vatican City, which is also a country, became party to the UN's international climate framework, which presides over annual climate summits. And in the lead up to the COP28 climate talks in Dubai in 2023, the pope published an Apostolic exhortation, calling for binding action on climate.

The Pope's Strongest Statement

The 12-page document was the pope's strongest statement following the encyclical. In it, he blasted the greed and selfishness of the wealthy who consume the most, while emphasizing that the poor were the first victims of the climate crisis.

Disparities in Emissions

"The reality is that a low, richer percentage of the planet contaminates more than the poorest 50% of the total world population, and that per capita emissions for the richer countries are much greater than those of the poorest ones," he wrote.