CHANGES to Earth’s oceans, caused by volcanic activity, triggered the greatest extinction of all time, a new Edinburgh University study shows.
The event, which took place 252 million years ago, wiped out more than 90 per cent of marine species and more than two-thirds of the animals living on land.
It happened when Earth’s oceans absorbed huge amounts of carbon dioxide from volcanic eruptions.
This changed the chemical composition of the oceans – making them more acidic – with catastrophic consequences for life on Earth.
The study, co-ordinated by University researchers, is the first to show that highly acidic oceans were to blame.
The findings are helping scientists understand the threat posed to marine life by modern-day ocean acidification
The amount of carbon added to the atmosphere that triggered the mass extinction was probably greater than today’s fossil fuel reserves.
However, the carbon was released at a rate similar to modern emissions. This fast rate of release was a critical factor driving ocean acidification.
The Permian-Triassic Boundary extinction took place over a 60,000 year period. Acidification of the oceans lasted for around 10,000 years.
Ocean acidification was the driving force behind the deadliest phase of the extinction, which dealt a final blow to an already unstable ecosystem.
Increased temperatures and widespread loss of oxygen in the oceans had already put the environment under pressure.
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.