Forget the mass extinction event that wiped out the landlocked dinosaurs and 75 percent of all life – that was peanuts compared to the apocalypse that visited the world 252 million years ago. Colloquially known as the Great Dying, this wiped out as many as 96 percent of all species.
A little more serious, and the planet would have been sterilized. Everything alive on Earth today descended from that small band of survivors. If there was one event that defined our world more than any other, this was it.
A new study, published in Nature Communications, places the blame squarely on a near-continental-sized volcanic eruption that took place in Siberia all those millions of years ago. Led by the United States Geological Survey (USGS), this new study confirms what scientists have known for some time, but nails down the timing and the specifics a little more.
There's no doubt that the effusive eruption of the Siberian Traps – which created step-like lava flows all across northern Pangaea, the supercontinent that existed at the time – kicked-started the Great Dying. Although it produced a lava flow that lasted for around 1 million years, one which turned that part of the planet into a no-go hellzone, it wasn’t the lava that caused the mass extinction event.
This eruption happened to release a lot of volatile gases too, including 4.4 trillion tonnes of carbon monoxide, 75 trillion tonnes of sulphur dioxide - which rapidly turned into sulfuric acid droplets - and 85 trillion tonnes of carbon dioxide.
The first two are great reflectors and deflectors of incoming solar radiation, and as such, they triggered a period of sudden global cooling and dark skies. This would have caused photosynthesis all over the planet to stall or even shut down, which may have triggered a collapse in food chains – particularly in the oceans.
Then, the carbon dioxide took hold and the planet warmed dramatically, in terms of both absolute temperature and the speed in which the mercury ascended. It triggered a devastating global warming event, by any measure.
This new research looked at the volcanological deposits left behind by this ocean of fire. It found that the worst part of the mass extinction event, when most species began to die off, coincided with a change in how the lava was being erupted.