How did volcanoes and coal smoke initiate the Great Dying?

If there is ever a competition for best-named geological phenomenon, the Great Dying is surely a contender.
Over a relatively short period of time some 70% of vertebrates living on land and around 90% of ocean species were killed off. The end-Permian mass extinction, as it is more formally known, was quite simply the biggest disaster ever to hit life on Earth.
Until around a decade ago, the trigger for this deadliest of catastrophes 252 million years ago was often presented as the greatest murder mystery of all time, with scientists offering up some half a dozen “suspects”.
More recently, advances in dating techniques and new geological evidence have provided a very prominent smoking gun. Most earth scientists now agree the greatest of the Earth’s “Big Five” mass extinctions was triggered by 1 million years or so of intense volcanic activity.
Mystery solved then? Not entirely.
Constant eruptions produce layers of basalt (Credit: Kevin Schafer/Alamy Stock Photo)
Constant eruptions produce layers of basalt, like these surrounding the Grande Ronde River in North America (Credit: Kevin Schafer/Alamy Stock Photo)
Yes, somewhere in the range of 5 million cubic km of lava spewed out across what is now northwestern Siberia – enough to cover the Earth’s surface to a depth of about 10 metres – and it did so shortly before the start of the mass extinction. This triggered the release of huge volumes of greenhouse gases that drove global warming and critically disrupted the Earth’s life support systems.
The end-Permian mass extinction was quite simply the biggest disaster ever to hit life on Earth
However, the precise details of how this caused so many life forms to die out remain the subject of scientific discussion.
These debates are no mere academic dispute. The catastrophic event played a major role in shaping the flora and fauna we see today. Moreover, there are clear parallels between the environmental changes that occurred back then and those being seen today. Some say improving our understanding of a time when life almost died could boost the long-term survival prospects of our species.
In 1980, Luis and Walter Alvarez, a father and son team at the University of California, Berkeley offered new and compelling evidence that the most famous of the mass extinctions – the one that did for the dinosaurs 66 million years ago – was the result of a massive asteroid impact. This trigger