Mass Extinction Caused by Carbon Emissions Similar to Today's

Around 90% of marine life was wiped in "the great dying" 252 million years ago
Around 90% of marine life was wiped in "the great dying" 252 million years ago. REUTERS/Jorge Silva

Scientists are warning CO2 is being emitted into the atmosphere today at a comparable rate to the amount released millions of years ago which caused the biggest extinction event in the history of the planet.

Around 90% of marine life is thought to have been wiped out in an extinction event known as "the great dying", which was the bridge between the Permian and the Triassic periods 252 million years ago.

The cause of the event has been a matter of debate in the scientific community. But a team of researchers coordinated by the University of Edinburgh say they now have evidence that volcanic activity releasing huge amounts of carbon into the atmosphere caused the acidification of the oceans, wiping out the majority of life on earth.

The paper, published in the journal Science, warns that lessons from these findings should be applied to treatment of the oceans today, which have shown a rise in acidity as carbon emissions have grown.

"It's been debated for a long time as to what the actual killing mechanisms were and there's a fairly good consensus that the eruption of huge volcanoes in Siberia, known as the Siberian traps, produced global warming because it sent a lot of CO2 into the atmosphere," says Professor Rachel Wood, one of the authors of the report.

She adds: "So we know that global warming happened at this time, and we know the oceans became anoxic, lost their oxygen."

"It's been suggested for a long time there may have been ocean acidification, but no one had ever had evidence for it before. We now have the very first evidence for an ocean acidification event corresponding with a massive extinction."

The team measured the pH levels of limestone rocks taken from the United Arab Emirates - an area that was a sea-bed at the time interval of the mass extinction, and from this they made a climate model that proved the acidification of the ocean during this period.

"Here we have an example of acidification happening at a time when there was a rate of carbon increase into the atmosphere very similar to today," says Professor Wood.

"We have a parallel there, the rate at which the volcanoes put CO2 into the atmosphere naturally caused an acidification event, and that rate is very similar to the rate at which humans are emitting CO2 into the atmosphere."

The authors of the paper write that oceans can absorb carbon emissions safely, but at higher levels the CO2 starts to change the chemistry of the oceans.

A report by the International Council for Science released in 2013 warned that ocean acidity could increase 170% by the end of the century due to carbon emissions, which would have serious effects on marine biodiversity as well as the economies of communities that rely on them.

Professor Wood says these new findings are a stark warning: "First, it's a similar rate of CO2 put into the atmosphere as today. Second, in this case we can show that it corresponds to the oceans definitely going acidic, and thirdly it corresponds to a major mass extinction. Fourthly that mass extinction is happening somewhere you really don't want mass extinctions to happen which is in the most biodiverse ecosystems on the planet that live on the shallow tropical environment."