Two intense periods of volcanism triggered a period of global cooling which caused one of the most severe mass extinctions in Earth history, according to new research.
The study, published in Nature Geoscience, was conducted by scientists at the University of Plymouth, the University of Oldenburg, the University of Southampton and the University of Leeds.
They examined the effects of volcanism on ocean chemistry during a period of extreme environmental change around 450 million years ago.
This period brought about intense planetary cooling, which culminated in a glaciation and the major ‘Late Ordovician Mass Extinction’. It led to the loss of about 85% of species dwelling in the oceans, reshaping the course of evolution of life on Earth.
Through their research, the team identified that two exceptionally large pulses of volcanic activity across the globe – occurring in parts of present-day North America and South China – coincided very closely with two peaks in glaciation and extinction separated by about 10 million years.
They also discovered that widespread blankets of volcanic material laid down on the seafloor during the Ordovician Period would have released sufficient phosphorus into the ocean to drive a chain of events including climatic cooling, glaciation, widespread low oxygen levels in the ocean, and mass extinction.