Biologists have used conservative new estimates to prove that vertebrate species on Earth are disappearing faster than at any time since the extinction of the dinosaurs, and humans are now at risk of being wiped out. “[The study] shows without any significant doubt that we are now entering the sixth great mass extinction event,” one of the researchers, Paul Ehrlich from Stanford University in the US, said in a press release. Even worse, the research shows that we triggered the event ourselves.
Although many biologists have long believed that Earth is in the middle of a major extinction event, skeptics have argued that estimates were overstating how fast species were being wiped out as a result of inconsistent data. Scientists work out whether we’re in a major extinction event by comparing the current extinction rate to the background extinction rate – the rate at which you’d expect species to normally disappear.
By looking only at well-verified data and fossil records of vertebrates – our best-studied group of organisms – the new research came up with a background extinction rate that’s twice as high as previous estimates. But even using this background rate and the most conservative species loss estimates, the researchers found that animals are still being wiped out around 15 to 100 times faster than they should be – in fact, the rate of species loss hasn’t been this high since the dinosaurs disappeared 65 million years ago.
“Rather than the nine extinctions among vertebrates that would be expected to have occurred in normal geological circumstances since 1900, their conservative estimate adds in another 468 extinctions, spread among mammals, birds, reptiles, amphibians and fish,” Jan Zalasiewizc writes for The Guardian. At this rate, the team estimates that around 41 percent of all amphibian species and 26 percent of all mammals will be wiped out. Source: It’s official: scientists say we’re entering Earth’s sixth mass extinction