Predictions from ancient climate change

Rising global CO2 levels are driving acidification and deoxygenation of the world's oceans, with unknown consequences for marine life. Researchers can use isotopes (heavier or lighter versions of an element) to investigate whether high atmospheric CO2 was the cause of past marine extinction events.

The EU-funded PERMIAN-TRIASSIC CAS (Investigating the effects of past global ocean acidification on marine ecosystems: A novel multiproxy approach) project aimed to use changes in various isotopes in the geological record to understand major oceanic extinction events. Specifically, researchers looked at the mass extinction event at the end of the Permian period (300-250 million years ago).

Principally, the project was looking for the impact of a rapid increase in atmospheric CO2 at the end of the Permian, caused by volcanic activity. It achieved this by studying isotope fluctuations in carbonate and black shale deposits in Australia, Canada, China, Italy, Norway, Oman and Turkey.

Project members found that the Permian mass extinction was linked to a loss of oxygen in the world's oceans. The project also found that the most likely cause was global warming, which affected ocean chemistry for nearly a million years.

This research further showed short-term ocean acidification events around the same time as the mass extinction. Similar environmental changes were observed prior to another major climate change event, in the late Neoproterozoic period.

PERMIAN-TRIASSIC CAS has shown the overwhelming effects that increased global CO2 can have on ocean life through acidification and deoxygenation. These findings provide insight into the potentially devastating effects of current rapidly increasing CO2 levels.