'Volcanic eruption caused largest mass extinction in history'

Last Updated 03 May 2018, 05:37 IST

Scientists from the University of Calgary who found layers of coal ash in rocks from the extinction boundary in Canada's High Arctic, said huge volcanic eruptions were the reason behind the mass extinction that devastated life on Earth at that time.

The last Permian extinction, also known as the Great Dying, is believed to have taken place about 250 million years ago. It saw 95 per cent of sea life wiped out and 70 per cent of animals on land killed, the researchers said.

While it is widely accepted that a meteorite was at least the partial cause for ending the dinosaur era 65 million years ago, it was unclear what led to the earlier, more severe extinction, the Daily Mail reported.

Past studies had suggested massive volcanic eruptions through coal beds in Siberia generated significant greenhouse gases that in turn caused runaway global warming.
Now, the University of Calgary team suggested that the discovery of layers of coal ash in rocks from the extinction boundary at Buchanan Lake in Canada is the first direct proof to support that volcanic eruption caused the extinction.

Lead researcher Dr Steve Grasby said: "This could literally be the smoking gun that explains the latest Permian extinction.

"Our research is the first to show direct evidence that massive volcanic eruptions -- the largest the world has ever witnessed -- caused massive coal combustion thus supporting models for significant generation of greenhouse gases at this time."

At the time of the extinction, Earth contained one big land mass, a super-continent known as Pangaea. The environment ranged from desert to lush forest.

Four-limbed vertebrates were becoming more diverse and among them were primitive amphibians, early reptiles and synapsids -- the group that would, one day, include mammals.

The location of volcanoes, known as the Siberian Traps, are now found in northern Russia covering an area about two million square kilometres -- a size greater than that of Europe.

The ash plumes from the volcanoes travelled to regions now in Canada's Arctic where coal ash layers where found.

"Our discovery provides the first direct confirmation for coal ash during this extinction as it may not have been recognised before," said co-researcher Dr Hamed Sanei.

The ash, the authors suggested, may have caused even more trouble for a planet that was already heating up with its oceans starting to suffocate because of decreasing oxygen levels.

(Published 24 January 2011, 12:03 IST)

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