Greatest extinction on Earth driven by acidic oceans

Ocean acidification triggered Earth's greatest extinction of all time, wiping out more than 90 per cent of marine species and over two-thirds of land animals some 250 million years ago, a new study has found.
Researchers found that oceans on Earth absorbed huge amounts of carbon dioxide from volcanic eruptions which changed the chemical composition of the oceans - making them more acidic - with catastrophic consequences for life on the planet.
The amount of carbon added to the atmosphere that triggered the mass extinction was probably greater than today's fossil fuel reserves, according to the study published in the journal Science.

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 study found.
The researchers analysed rocks unearthed in the United Arab Emirates - which were on the ocean floor at the time - to develop a climate model to work out what drove the extinction.
"The Permian-Triassic Boundary extinction took place over a 60,000 year period. Acidification of the oceans lasted for around 10,000 years," researchers said.

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," said researcher Matthew Clarkson of the University of Edinburgh's School of GeoSciences.
"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," he said.