The extinction crisis is far worse than you think (CNN)

The extinction crisis is far worse than you think. In all of Earth's history, there have been five mass extinction events. You can see them charted here. Now, we're on the verge of the sixth extinction. And three-quarters of all species could vanish. Imagine three out of four species that were common are gone. ...
http://www.cnn.com/interactive/2016/12/specials/vanishing/index.html