Pope Francis, who chose his papal name after the 13th-century figure St. Francis of Assisi, known as the patron saint of ecologists, was the fiercest climate and environment advocate in the church’s history.

I am not Catholic, but I mourn the pope's death because he spoke for so many of us,' an L.A. Times reader writes.

Pope Francis regularly used his position to push for action on climate change, notably in two papal documents that wove scientific fact with faith-based arguments for safeguarding the planet.