Hour 1: In the last 500 million years, there have been five mass extinctions on Earth. And some scientists are saying we should prepare for the next one. We’ll speak with New Yorker staff writer, Elizabeth Kolbert, about her new book, The Sixth Extinction: An Unnatural History.

Hour 2: Pope Francis is facing challenges after, Pope Benedict XVI, resigned in 2013. We’ll talk this hour with, Antony Thomas, director of Secrets of the Vatican, a Frontline special that airs Tuesday on KERA TV.