Climate change may fuel a mass extinction in which half of all plant and animal species could — how to put this delicately? — exit stage left, according to a new study. If the past 520 million years of fossil records are any predictor of the future, a globally warmed world will not bode well for biodiversity, researchers found. “We found that over the fossil record as a whole, the higher the temperatures have been, the higher the extinctions have been,” said University of York ecologist Peter Mayhew. The study also found that four of five of the world’s mass extinctions occurred when the Earth was significantly warmer, and that in cooler times, biodiversity tends to be higher. Researchers warned that the Earth is on track to hit temperatures similar to the higher, extinction-correlated ones in about 100 years or so.