Reuters: It is one of science's enduring mysteries: what caused the worst mass extinction in Earth's history. And, no, it is not the one that wiped out the dinosaurs.
Scientists said on Thursday that huge amounts of carbon dioxide spewed from colossal volcanic eruptions in Siberia may have turned the world's oceans dangerously acidic 252 million years ago, helping to drive a global environmental calamity that killed most land and sea creatures.
The researchers studied rocks in the United Arab Emirates...