This encore Reader's Corner interview first aired in September, 2018.
A handful of times in our planet’s history, the vast majority of plant and animal life has gone extinct, leaving a desolate and alien earth, devoid of trees, fish, and familiar signs of life. In the more recent past, scientists have pointed to asteroids to explain some of these extinction events. But today, that view is being questioned. More evidence is pointing towards terrestrial causes of our past extinctions, notably climate and ocean change, spurred by the influx of carbon dioxide in our atmosphere.