Volcanic fertilization of the oceans drove severe mass extinction, say scientists
The researchers, working with colleagues at the University of Oldenburg, the University of Leeds and the University of Plymouth, studied the effects of volcanic ash and lava on during a period of extreme environmental change around 450 million years ago. Their findings are published in the journal Nature Geoscience.

This period brought about intense planetary cooling, which culminated in a glaciation and the major 'Late Ordovician Mass Extinction'. This extinction led to the loss of about 85% of species dwelling in the oceans, reshaping the course of evolution of life on Earth.
"It's been suggested that global cooling was driven by an increase in phosphorus input to the oceans" says Dr. Jack Longman, lead author of the study based at the University of Oldenburg, and previously a postdoctoral researcher at Southampton. "Phosphorus is one of the key elements of life, determining the pace at which tiny aquatic organisms like algae can use photosynthesis to convert (CO2) into organic matter". These organisms eventually settle to the seabed and are buried, ultimately reducing levels of carbon dioxide in the atmosphere, which then causes cooling.

Volcanic deposits both on land and on the seafloor are rapidly weathered, releasing nutrients like phosphorus to the oceans (example shown here is Montserrat, West Indies). Credit: Dr Tom Gernon/University of Southampton [@TMGernon]
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Volcanic deposits both on land and on the seafloor are rapidly weathered, releasing nutrients like phosphorus to the oceans (exame shown here is Montserrat, West Indies). Credit: Dr Tom Gernon/University of Southampton [@TMGernon]
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Abrupt climate change at the end of the Ordovician Period (~450-440 million years ago) caused the second largest mass extinction in Earth history, including the demise of the trilobite, Selenopeltis (pictured, in Oxford University Museum of Natural History). Credit: Dr Tom Gernon/University of Southampton [@TMGernon]
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