We have become used to a potential threat from the outside, from space. The wipe-out of the dinosaurs 65 million years ago has had numerous copy-cats in popular culture. But the biggest mass extinction of them all was not caused by something from the outside. It was caused by the planet Earth it self. There are literary millions of tonnes of evidence left in Russia.
In eastern contemporary Russia, there are vast areas of geological formations formed by flood basalts. It’s the Siberian traps, the massive remains of the gigantic volcanic eruptions in the area that lasted for a million years. The area directly affected by the eruptions is equal in size to Western Europe. The eruptions started a chain reaction with dramatic consequences for the whole planet. It would take life five million years to recover; time was required for evolution to fill the many holes of lacking species.
Now, a group of scientists led by Shu-zhong Shen of Nanjing Institute of Geology and Palaeontology in China has read the rock. By sampling layers of rock spanning the mass extinction and collecting volcanic minerals, they have been able to make the most precise dating of the event so far. This is important, because the problem has previously been to match the volcanic eruptions with the mass extinction. Now, the estimated error is down to a 100 000 years. They came up with an estimated time for the event at 252.28 ± 0.08 million years, about a million year earlier than what is stated in most textbooks.
This new timing correlates with a rapid increase in CO2, a sharp drop in O2 and an addition of atmospheric aerosols. The authors conclude that these inputs could have resulted in a rapid global warming leading to widespread wildfires and accelerated deforestation, finally resulting in a massive soil-erosion. This is clearly a worst case scenario for the current global warming. If this would happen today, it would be the end of the world for us humans.
The earth was profoundly different before the mass extinction. There were still trilobites in the oceans, just as there had been for the 300 million years before that. The dominating large animals – terrestrial vertebrates – were differently built than the dinosaurs that would slowly take over after the event.
The mass extinction is preserved in rocks around the world, from the mountains of South Africa to southern China where this new research was conducted. And it was not only dinosaurs that evolved into domination after the extinction event, even our own linage, mammals, evolved after some tens of millions years. The conditions for evolution had been changed in the most dramatic way possible.
One thing is for certain – if the massive volcanic eruptions had not taken place, if there had been no mass extinction at the end of the Permian period, life on earth would have looked different today. And I don’t think I need to stress how important these new findings are in the light of the current occurring global warming?