A clue to what may have triggered this disaster lies in solidified magma from this time, which is widespread in an area of Siberia where coal is also abundant.
In a new research, scientists have suggested that fiery mountains of coal might have caused the most devastating mass extinction on Earth around 250 million years ago.
Around 250 million years ago, the so-called "Great Dying" saw 70% of species wiped out on land and 95% in the oceans.
A clue to what may have triggered this disaster lies in solidified magma from this time, which is widespread in an area of Siberia where coal is also abundant.
One suggestion is that the heat of the magma could have baked many billions of tonnes of CO2 out of the coal over a geologically brief period of a few thousand years.
The ensuing climate change and ocean acidification would account for the extinctions.
Now, according to a report in New Scientist, Norman Sleep and Darcy Ogden, both of Stanford University in California, think the trigger for the Great Dying may have been even swifter and more terrifying.
Rather than causing gentle heating, magma encountering oil- and tar-soaked coal underground would melt it, producing a highly combustible material.
Crucially, this molten mixture would be light enough to rise quickly to the surface.
There, it would burn explosively on contact with oxygen in the air, blasting dust and ash into the stratosphere and releasing huge quantities of CO2.
A molten mixture of magma and coal would burn explosively on contact with air.
"You're basically going to have something like a fire fountain every few kilometres or so over this vast moonscape that's erupting, with flares going high into the air and columns of smoke and fly ash," said Sleep.
The ground would be "covered with coal tar and coal fragments and pieces of basalt", he added.
Dust injected into the stratosphere would cause drastic cooling. That would quickly switch to warming as the dust settled out of the atmosphere, leaving nothing to counteract the greenhouse effect of the increased CO2.
The climate might have swung between heating and cooling as new eruptions injected yet more dust into the stratosphere.
"The climate is just going to go completely unstable," said Sleep.
If Sleep and Ogden are right, proof of their scenario may be hiding in Siberia's abundant volcanic deposits.
In a burning mixture of coal and magma, the carbon in the coal would strip oxygen from iron oxide in the magma, leaving behind particles of iron.
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