Climate change may have triggered a mass extinction event that wiped out around 85 per cent of all marine species on Earth hundreds of millions of years ago, according to academics.
Researchers have discovered that global warming caused by volcanic eruptions may have led to the Late Ordovician extinction, which happened nearly 450 million years ago.
Scientists have previously linked the extinction event to toxic metals and radiation released from a distant galaxy and global cooling.
But Professor David Bond from the University of Hull and Dr Stephen Grasby from the Geological Survey of Canada now believe global warming - which has been linked to many of history’s other mass extinctions - is a more likely explanation.
Their research, which has formed a publication in the journal Geology, found that when Ordovician rocks collected from a small stream in southern Scotland were heated, they released large amounts of mercury - a sign volcanic eruptions took place during that period.
The rocks also emitted molybdenum and uranium, suggesting the oceans were starved of oxygen at the same time.
Professor Bond and Dr Grasby have suggested the widespread eruptions released enough carbon dioxide to heat up the planet and deoxygenate the oceans, resulting in the asphyxiation of the species that lived there.
Professor Bond told the New York Times: “Think of a bottle of Cola. If it’s been in the fridge, it stays nice and fizzy because the gas in that carbon dioxide stays in the liquid.
“But if you leave it on a sunny table outside and it gets really warm, then that gas quickly dissociates out of that liquid and you end up with a flat Coke.”
Previous theories about the Late Ordovician extinction have focused on widespread glaciation towards the end of the period, which experts have said could have caused shallow seas to disappear, impacting on the species that lived there and disrupting the food chain.
But some scientists have discounted this explanation due to evidence showing the extinction was an abrupt event, while glacial events often span millions of years.
The new research does not discount glaciation at the time but suggests the cooler climate was then impacted by global warming events triggered by volcanic eruptions.
Dr Grasby said: “The Ordovician one has always been a little bit of an oddball.”
