Earth's greatest mass extinction 250 million years ago shows what happens when El Niño gets out of control

Around 252 million years ago, the world suddenly heated up. Over a geologically brief period of tens of thousands of years, 90% of species were wiped out. Even insects, which are rarely touched by such events, suffered catastrophic losses. The Permian-Triassic mass extinction, as it's known, was the greatest of the "big five" mass extinctions in Earth's history.