Stinking seas not the cause for 'mother of all mass extinctions' during the Permian

At the end of the Permian era, as much as 95 per cent of marine species and 70 per cent of land species were wiped out. Initially it was thought rotting gas (hydrogen sulfide) from the seas was the main culprit but scientists have disproved that theory.

It was called “the Great Dying” or “the mother of all extinctions”, when mass extinctions occurred 250 million years ago at the end of the Permian era. Scientists believe the extinction occurred over a period of millions of years and they found plenty of evidence of fossilized, mutant plant spores worldwide to support the mass extinction. But no one knows for sure what caused the extinction. The extinction could have been cause by a number of factors. It could have been by an asteroid, similar to the event believed to be the cause of the dinosaur extinction some 62 million years ago. This could have generated a dust storm that could have darkened the skies preventing sunlight on earth, decimating vegetation and killing the food supply for many animals and creatures. Volcanism, the phenomena associated with volcanic activity, is another theory; severe volcanic activity on Earth could have caused a lethal mixture of acid rain and global warming. This could have wiped out most of the plant and animal species. Oceans became starved of oxygen and rich with hydrogen sulfide, which gives a rotting gas smell. This gas then rises from the seas and along with methane from volcanic activity it could have attacked the ozone layer that keeps out ultraviolet rays from the sun. This could have decimated Earth's creatures by poisining them with hydrogen sulfide and then exposing them to high radiation from the sun. Among the three theories, many thought the “stinking seas” could have caused the mass extinction. But a team led by David Beerling of the University of Sheffield in northern England found hydrogen sulfide couldn’t have been the main reason for the mass extinction. They created a two-dimensional computer model of atmospheric chemistry to test this theory. As physorg.com reports, they found from their calculations that:

the lower levels of the atmosphere in the tropics would have acted as an oxidizing buffer, preventing the hydrogen sulphide from seriously damaging the ozone layer.

Their main finding:

These gases seem unlikely to be the cause of coincident terrestrial biotic extinctions.”

They have published their work in the Nature Geoscience journal this week. It is imperative the scientists find the true cause for mass extinctions, so mankind can better react if the same circumstances present come up again.