O’DONNELL: Francis is also the first pontiff to make climate change a priority. In 2015, to make an important point, images of the environment were projected onto St. Peter's Basilica, the dome designed in the mid-16th Century by Michelangelo. What do you say to the deniers of climate change?
POPE FRANCIS: There are people who are foolish, and foolish even if you show them research, they don't believe it. Why? Because they don't understand the situation or because of their interest. But climate change exists.
O’DONNELL: His progressive style has made him popular worldwide, with millions coming here to St. Peter's Square to catch a glimpse of the Holy Father.