Volcanism-induced ozone depletion may have contributed to Permian mass extinction, study finds

The end- Permian event is considered to be the largest of the "Big Five " extinction events through the planet's geological history.

During this catastrophe, it is estimated that ~81% of all marine species and ~70% of terrestrial vertebrate species became extinct.

The process by which volcanic emissions resulted in this planetary catastrophe relates to the photolysis (molecule breakdown due to the absorption of light) of sulfur dioxide by ultraviolet radiation.