Catholic popes have been urging global leaders to address social justice issues for 135 years across some two dozen major documents that many of the world's 1.4-billion-faithful can cite by their two- or three-word titles.

"Rerum Novarum" from Leo ‌XIII in 1891 called for better conditions for workers in the Industrial Revolution. "Pacem in Terris" from John XXIII in 1963 appealed for nuclear disarmament amid the Cold War. "Laudato Si'" from Francis in 2015 pleaded for swift action to address climate change.