Researchers have found a chemical clue in Italian limestone that explains a mass extinction of marine life in the Early Jurassic period, 183 million years ago. Volcanic activity pumped out CO2, warming oceans and lowering their oxygen levels. The findings may foretell the impact climate change and oxygen depletion might have on today's oceans.
During the Jurassic Period, when marine reptiles like ichthyosaurs and plesiosaurs thrived, volcanic activity in modern South Africa released an estimated 20,500 gigatons of carbon dioxide over 500,000 years. This heated the oceans, causing them to lose oxygen.
But Kipp said that today's rapid rate of atmospheric CO2 release is unprecedented in history, making it hard to predict when another mass extinction might occur or how severe it might be.