Most scientists agree that there have been five mass extinctions in Earth's history. Kolbert, a respected environmental journalist, believes we're on the verge of number six, the first since the dinosaurs were wiped out more than 50 million years ago. What does this mean for the planet? We'll find out when The Sixth Extinction appears sometime next year.
From our archives: a review of the audio version of Kolbert's previous book, Field Notes from a Catastrophe.