Several times life on Earth has experienced moments on the brink of complete destruction. The largest extinction was the Permian-Triassic, which is also called the “Great Extinction”, which occurred about 252 million years ago. What happened then?
In the period of the most significant extinction, up to 96% of all marine species and 70% of terrestrial vertebrates died. Scientists have been struggling for many years with the question of what caused it, and it seems they have found the answer. They looked at different scenarios, including impact events, climate change caused by methane bacteria, massive volcanic eruptions, and some lesser known potential causes such as a fungal spike. There is evidence for each hypothesis, but they still remain controversial.
The authors of the new study say they have finally found the exact cause. The document “Permian-Triassic Mass Extinction Impulses Caused by Major Disturbances in the Marine Carbon Cycle” is published in Nature Geoscience.
“Our research provides the first accurate reconstruction of the carbon source and with it the trigger of the crisis, and uncovers the subsequent chain of processes that led to the largest mass extinction on Earth,” said Hana Jurikova, lead author at the University of St Andrews.
Researchers studied the shells of brachiopods from Italy and China, and it turned out that it was the sharp surge in CO2 that caused the Permian-Triassic extinction. The pulse originated in Siberia, where a powerful volcanic eruption created a massive basalt province. As a result, a huge amount of CO2 was released into the atmosphere – 100,000 billion tons.