Volcanoes led to world's largest extinction: study

The world's biggest extinction was triggered by a massive volcanic eruption, burning coal and steep increases in greenhouse gases, say researchers at the University of Calgary.

About 250 million years ago, before the age of the dinosaurs, the Permian extinction wiped out 95 per cent of life in the oceans and 70 per cent of life on land. While scientists have long suspected volcanic eruptions in Siberia were to blame, the Calgary team says it has found credible evidence to back up the theory.

Stephen Grasby, a geoscientist with the University of Calgary and research scientist at Natural Resources Canada, says he and his colleagues found evidence of the eruption in the Canadian Arctic. Specifically, they found layers of coal ash in rocks from the time of the 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," Grasby said in a release.

The results of the research are published in the current issue of Nature Geoscience.

During the Permian extinction, the Earth was basically one big land mass called Pangaea, containing ecosystems ranging from desert to lush forest. Pangaea was home to primitive amphibians, early reptiles and synapsids: the group that would one day include mammals.

The volcanoes that erupted so spectacularly and signalled the beginning of the end for so many plants and animals of this period are now found in northern Russia. The ash was blown to regions now in Canada's Arctic.

"It was a really bad time on Earth," said Grasby. "In addition to these volcanoes causing fires through coal, the ash it spewed was highly toxic and was released in the land and water, potentially contributing to the worst extinction event in earth history."

It took five million years for the planet to rebound and for higher life forms to reappear.