The greatest extinction in Earth's history, superior to that of dinosaurs. It occurred 250 million years ago and between 90% and 95% of marine species and about 70% of terrestrial species disappeared. Why?
That is debated. There are several theories: It was the origin of Pangea, glaciations, volcanoes or methane.
Two new articles in the journal Geology mention this last idea. In one of them, Gregory Ryskin estimates that a huge volume of methane accumulated in the seabed. This methane began to be released by an earthquake or another, which caused the decrease in water pressure to cause, in turn, a greater release of methane. The arrival of methane into the atmosphere caused large explosions, 10,000 times more intense than the joint explosion of all current nuclear weapons. According to Ryskin, the smoke and soot generated by these explosions caused nuclear winter or global climate warming.
In the other article, published a little earlier, methane did, but there were no explosions. Methane slowly released from the sea and became an unbreathable atmosphere.