Massive volcanic eruptions 250 million years ago may have triggered the biggest ever extinction of living species on Earth, Canadian scientists have said in research published in this week's Nature Geoscience journal.
The research findings represent the first direct link between greenhouse gases generated because of the volcanic eruptions and the massive extinction at the time. About 95 % of sea life and 70 % of the life on land was wiped out 250 million years ago.
There has till now been no clear explanation for this extinction – known as the late Permian extinction – unlike the death of the dinosaurs 65 million years ago which is generally attributed at least in part to a meteorite impact.
"This could literally be the smoking gun that explains the late Permian extinction," said scientist Steve Grasby, a professor at the University of Calgary's Department of Geoscience and an author of the research.
The Earth contained one big land mass known as the Pangaea at the time, 250 million years ago, when the extinction occurred. This single continent contained environment ranging from desert to lush forest.
Grasby and his colleagues at the University of Calgary and at Natural Resources Canada – the Canadian government's department of natural resources – discovered layers of coal ash at the extinction boundary in Canada's High Arctic.
The volcanoes – known as the Siberian Traps – are located in northern Russia, and cover an area larger than the size of Europe. Ash plumes from the volcanoes traveled to regions now in Canada's Arctic.