Ocean acidification caused mass extinction

Scientists have warned about the acidification of the world’s oceans, after new research from the University of Edinburgh revealed the phenomena was likely to have caused the greatest mass extinction in the earth’s history.

The study found that the end-Permian extinction 252 million years ago, which killed 90 per cent of marine species and more than two-thirds of the animals living on land, was likely to have been caused by ocean acidification brought about by increased volcanic activity.

The findings, released in the journal Science, were reached through analysis of rocks discovered in the United Arab Emirates which were on the ocean floor at the time.

The mass extinction of both marine and land-based animals demonstrates that extreme change took place in all of Earth’s ecosystems.

Although the study suggests the amount of carbon released into the atmosphere, triggering the extinction, was probably greater than today's fossil fuel reserves, the rate the carbon was released was probably similar to present levels.

It found that the speed of release was a critical factor driving ocean acidification.

The Permian-Triassic Boundary extinction took place over a 60,000 year period, with the effects of ocean acidification continuing for around 10,000 years after.

Dr Matthew Clarkson, of the University of Edinburgh’s School of GeoSciences, who co-ordinated the study, said: “Scientists have long suspected that an ocean acidification event occurred during the greatest mass extinction of all time, but direct evidence has been lacking until now. This is a worrying finding, considering that we can already see an increase in ocean acidity today that is the result of human carbon emissions.”

Professor Rachel Wood, of the University of Edinburgh’s School of GeoSciences, said: “This work was highly collaborative and the results were only possible because we assembled a unique team of geochemists, geologists and modellers to tackle an important and long-standing problem.”

The University of Bremen, Germany, and the University of Exeter, together with the Universities of Graz, Leeds, and Cambridge all contributed to the project.