5 possible 6 mass level extinction events, with extinction rates as high as 97% of the earths species. These events themselves are understood as occurring over millions of years which is a blink of an eye in terms of a geological time frame, which should suggest something in regard to modeling and prediction here. Some biologists suggest we are at the start of a new mass extinction event, which unlike the others is of human origin. That makes it less predictable as human agency and the ability to alter human behavior is a factor. Tendency to view these events from a human focused perspective. i.e. conflating the end of human existence with the eradication of all biological life.