A new hypothesis has emerged in the search for the cause of Earth's greatest ever mass extinction: The Permian-Triassic Mass extinction event (~250 million years ago).
A study published today in Nature Geoscience1 suggests that one trigger for the near-apocalyptic 'great die-off', which killed 96% of marine species and 70% of land-based vertebrate organisms, was a volcanic explosion in coal and shale deposits in Siberia. Within days, ash from the eruption, raining down onto the Canadian Arctic, sucked oxygen from the water and released toxic elements.
"The magma went through a juicy bit of crust that it can release a lot of nasty things from," says Paul Wignall, a palaeontologist at the University of Leeds, UK, who studies mass extinction events.
This may have been the tipping point, says Wignall. Studies have suggested the volcanoes released 3 trillion tonnes of carbon, enough to trigger massive climate change. The eruptions also caused acid rain and emitted sufficient halogens to create an ozone hole, he says. Toxic fly ash, on top of all this, may have been the final blow.
"I can't suggest that this is the answer to the mass extinction story, but it is a new component to it," he says. "It is like throwing the kitchen sink at the world."