Carbon increase at time of mass extinction matches today’s emissions

An apocalyptic event dubbed "the Great Dying" and that was the greatest extinction event ever known could be worryingly relevant to humans today, scientists say.

A team of researchers including a New Zealand scientist have helped shed light on what caused the annihilation about 252 million years ago of 90 per cent of the planet's marine species and more than two thirds of the animals living on land.

Volcanic eruptions loaded the Earth's oceans with massive amounts of carbon dioxide, increasing the acidity of the great water masses with catastrophic consequences.

That highly-acidic oceans were to blame for what is formally known as the Permian-Triassic Boundary extinction has been shown for the first time in a study published today in the international journal Science.

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Dr Matthew Clarkson, a postdoctoral fellow at Otago University's department of chemistry, who co-authored the study, said the findings were helping scientists understand the threat posed to marine life by modern-day ocean acidification.

While the amount of carbon added to the atmosphere to trigger the mass extinction was probably greater than today's fossil fuel reserves, it was released at a rate similar to modern emissions.

The team analysed an ancient but detailed record contained in what were once ocean-floor rocks to work out what drove the extinction.

They found the rapid rate of carbon release was a critical factor in ocean acidification.

The extinction event lasted tens of thousands of years - vastly longer than the extinction that wiped out the dinosaurs after the impact of a comet or asteroid - but the most deadly phase occurred within the 10,000 years of ocean acidification.

"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," Dr Clarkson said.