The scale of the extinction after the volcanic eruption was incredible. Photo / 123rf
The scale of the extinction after the volcanic eruption was incredible. Photo / 123rf
Scientists have unravelled the cause of the largest mass extinction in the history of Earth, which wiped out 90 per cent of all life on the planet around 250 million years ago.
Dubbed the Great Dying, the catastrophic event was triggered by a massive volcanic eruption that scientists believe ran for up to one million years in what is today Siberia, the Daily Mail reports.
Until now, scientists were unsure of how the so-called Flood Basalts eruption was responsible for wiping out such a large proportion of life on Earth, since previous volcanic activity of this scale had not killed anywhere near as many species.
Some had suggested the eruption blanketed the Earth in a dense smog that blocked the sun's rays from reaching the planet's surface.
However, a new study has revealed how chemicals released by the eruption released a huge reservoir of deadly chemicals into the air that stripped Earth of its ozone layer.
This eradicated the only protection Earth's inhabitants had against the sun's deadly UV rays, causing the death toll to skyrocket, compared to other major eruptions.
Scientists at the Centre for Petrographic and Geochemical Research in Vandœuvre-lès-Nancy, France, studied rock from Earth's upper mantle to determine the cause.
Scientists analysed the chemical composition of mantle xenoliths (pictured), rock sections of the lithosphere that get captured by passing magma and erupted to the surface. Photo / Michael Broadley
They analysed the chemical composition of mantle xenoliths, rock sections of the lithosphere – a section of the planet located between the crust and the mantle – that gets captured by passing magma and erupted to the surface during eruptions.
Through analysis of the ancient samples, researchers attempted to determine the composition of the lithosphere.
They found that before the Flood Basalts took place, the Siberian lithosphere was heavily loaded with chlorine, bromine, and iodine.
These chemicals, all elements from the halogen group, seemed to disappear soon after the devastating volcanic eruption.
"We concluded that the large reservoir of halogens that was stored in the Siberian lithosphere was sent into the earth's atmosphere during the volcanic explosion," said study lead author Michael Broadley.
"This effectively destroyed the ozone layer at the time and contributed to the mass extinction."
Around 95 per cent of marine life and 70 per cent of life on land was wiped out in The Great Dying 252 million years ago.
All life on Earth today is descended from the roughly 10 per cent of animals, plants and microbes that survived the mass extinction event.
Previously it was thought the eruption was so deadly because it blanketed the Earth in thick smog that blocked the sun's rays from reaching the planet's surface. Photo / 123rf
Previously it was thought the eruption was so deadly because it blanketed the Earth in thick smog that blocked the sun's rays from reaching the planet's surface.
"The scale of this extinction was incredible," said Broadley.
"Scientists have often wondered what made the Siberian Flood Basalts so much more deadly than other similar eruptions."
Around 248 million years ago the Permian period ended and the Triassic period began.
The Permian mass extinction has been nicknamed the 'The Great Dying' as nearly all life on Earth was exterminated.
A staggering 96 per cent of all life on the planet was destroyed.
All life on Earth today is descended from that existing 4 per cent of species.
The cause of the mass extinction remains unclear to scientists, although it is thought to have lasted anywhere between 20,000 years to millions of years.
The third largest extinction in Earth's history saw a severe ice age cause sea level falling by 100m, which wiped out 60-70 per cent of all species - most of life on Earth was in the sea.
Late Devonian - c 360 million years ago
Three quarters of all species on Earth became extinct after a prolonged climate change event, with shallow seas the worst affected areas. Reefs were also hard hit, which saw nearly all corals disappearing.
Permian-Triassic - c 250 million years ago
Aptly nicknamed "The Great Dying", the third mass extinction saw 96 per cent of species dying out. Massive volcanic eruptions in Siberia were strongly linked to the savage episode of global warming responsible for the extinction.
