BBC: Acidic oceans helped fuel the biggest mass extinction in the history of life on Earth, a study says.
The exact causes behind the Permian-Triassic mass extinction have been much debated.
Two separate pulses of CO2 into the atmosphere - a "one-two punch" - may have helped fuel the die-off, new research suggests.
Changes to ocean acidity would have been one of the consequences, according to the study in Science journal.
Computer models suggested that this CO2 may have been released by massive...