extinction2_h1It has all the signs of a sick good-news/bad-news tale. The bad news is that Earth may be ripe for a mass extinction, where 75 percent or more of the life on the planet vanishes forever.

The good news is it’s unlikely to happen for at least three more centuries.

Scientists writing in the journal Nature warn that we could be on the brink of a mass extinction, the kind of species loss that has happened just five times in the last 540 million years.

“If you look only at the critically endangered mammals–those where the risk of extinction is at least 50 percent within three of their generations–and assume that their time will run out and they will be extinct in 1,000 years, that puts us clearly outside any range of normal and tells us that we are moving into the mass extinction realm,” Anthony Barnosky, an integrative biologist at the University of California at Berkeley said in a statement about the study he co-wrote.

extinction3_h2Are humans to blame? Possibly.

“A modern global mass extinction is a largely unaddressed hazard of climate change and human activities,” said H. Richard Lane of the National Science Foundation, which funded the research.