SIXTH EXTINCTION: Humans have killed off at least 322 animal species, including tortoises (and dodos) on the islands of Mauritius. But imported tortoises from the Seychelles, like this one, may be able to fill that loss.
Photo Credit: Scientific American
The most famous mass extinction came from space, but the biggest might have been because of carbon dioxide. Cataclysms, whether the asteroid that ended the dinosaurs’ reign or the volcanism that may have caused the Great Dying, drove the first five mass extinctions in Earth’s history, in which 75 percent of more of the planet’s life died out. The sixth mass extinction may now be beginning—and the apocalypse this time is us.
During the last several centuries we have burned through eons worth of fossilized sunshine, changing the climate for our fellow species. We use more than half of the planet’s unfrozen land for cities, logging or food, eliminating the habitats of our fellow animals and plants. Before we even achieved civilization, we had already helped hunt the biggest, fiercest animals—woolly mammoths, giant kangaroos and giant sloths—to extinction.