Will Humans Survive the Sixth Great Extinction?

In the last half-billion years, life on Earth has been nearly wiped out five times—by such things as climate change, an intense ice age, volcanoes, and that space rock that smashed into the Gulf of Mexico 65 million years ago, obliterating the dinosaurs and a bunch of other species. These events are known as the Big Five mass extinctions, and all signs suggest we are now on the precipice of a sixth.