"The Earth has known several mass extinctions over the course of its history.
One of the most important happened at the Permian-Triassic boundary 250 million years ago.
Over 95% of marine species disappeared and, up until now, scientists have linked this extinction to a significant rise in Earth temperatures.
But researchers have now discovered that this extinction took place during a short ice age which preceded the global climate warming.
It’s the first time that the various stages of a mass extinction have been accurately understood and that scientists have been able to assess the major role played by volcanic explosions in these climate processes..."