Findings shed light on climate change

Matthew Clarkson.
Matthew Clarkson.
Big changes in the earth's oceans contributed to the greatest mass extinction of all time, research into which has provided a ''wake-up call'' about the dangers of modern climate change.

That comment was made by University of Otago chemistry postdoctoral fellow Dr Matthew Clarkson, who co-ordinated a just-published international study which sheds new light on the mass extinction.

And the research provides new scientific support for the concept that ocean acidification played a crucial role in the mass extinction.

The changes in the earth's oceans were caused by extreme volcanic activity, and led the mass extinction event, known as the ''Great Dying'', which took place 252 million years ago.

This wiped out more than 90% of marine species and more than two-thirds of the animals living on land.

It happened when the earth's oceans absorbed huge amounts of carbon dioxide from volcanic eruptions, the researchers say. This changed the chemical composition of the oceans - making them more acidic - with catastrophic consequences for life on Earth.

The study, co-ordinated by Dr Clarkson while he was a PhD student at the University of Edinburgh, was the first to show that highly acidic oceans were to blame.

The findings have just been published in a leading international journal, Science, and Dr Clarkson said that the study outcome was ''really exciting''.

He was ''interested to see what happens after this'' as other scientists responded to the new study.

The study involved a collaboration with the University of Bremen, in Germany, as well as with the University of Exeter, together with the Universities of Graz, Leeds and Cambridge.

Dr Clarkson and the team said the findings were 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, but the carbon was released at a rate similar to modern emissions.

Oceans can absorb some carbon dioxide but the large volume released ''at such a fast rate'' changed the chemistry of the oceans, the team says.

Findings on the earlier ocean acidification provided ''a bit of a wake-up call'' regarding the risks surrounding the more recent build-up of atmospheric carbon dioxide, he said in an interview.

''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.

The underlying science behind modern climate change had been known for some time, and Dr Clarkson said he hoped the study involving his research would help ''hit home the message'' about the dangers of rising atmospheric carbon dioxide levels.

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