The Great Dying, also referred to as the Permian-Triassic extinction or the Great Permian extinction. About 252 million years ago, here on Earth, something went horribly wrong. After life had been developing to new heights throughout most of the Paleozoic era, 252 million years ago, up 96% of all marine species and 70% of all terrestrial vertebrate species vanished.
The reason as to how 57% of all biological families and 83% of all genera became extinct is something we still aren't too sure about today. At the start of the Permian period, the Earth's atmosphere was richer in oxygen to 23% while carbon dioxide levels were around 900 parts per million, about over two times the current levels. The average surface temperature was about 16 degrees and sea levels were at 60 meters below their present. Climate in the Permian period was quite varied. At the start of the Permian period the earth was still in an ice age, which began earlier in the Carboniferous period.
The most prominent and noticeable change the Permian brought was the formation of a new supercontinent, Pangea. Glaciers receded around the mid-Permian as the climate gradually warmed, due to the formation of the supercontinent Pangea. This was the main change during the Permian.
The formation of a supercontinent created vast amounts of desert land on Earth, as the rain clouds weren't able to reach that far inland, and soon the land dried. In a few thousand years, Pangea dried out and a vast desert larger than any ever seen on Earth would form. To be specific, on Pangea there formed two deserts, as Gondwana and Laurasia merged together in the early Permian, a mountain range formed between them, separating a northern and a southern desert. The Permian saw the completion of a saga that had been going on since the Carboniferous.
The rise of the reptiles. Reptiles like Dimetrodons dominated the early Permian. While they diversed more towards the end of the Permian, the new dry desert environment was perfect for reptiles to thrive in.
Scutosaurs, Decynodons, Gorgonopsids and others thrived here. Despite harsh conditions, life remained doing well. Then...
252 million years ago, on the end of the Permian and start of the Triassic period, all of this collapsed in the greatest mass extinction life on earth has ever seen. Unlike the meteor that wiped out the dinosaurs 66 million years ago, the cause for the Permian extinction is less clear. Not only because it happened far longer ago, but also because in all likelihood there wasn't a single cause. The Permian extinction likely started with one Kickstarter event that put into motion a tragic sequence leading to the Great Dying. The sequence and its trigger have puzzled scientists ever since the first evidence for the event was first discovered.
One of the first clues we got was from sedimentary rocks, pointing to a rapid increase in the Earth's temperature at the end of the Permian. The temperatures might have risen by as much as 11 degrees centigrade in a short amount of time. This was already evidence against an asteroid strike being the cause, as the ash of the impact would have blocked the Sun and caused temperatures to fall rather than rise.
On top of that an asteroid impact would cause an extinction really fast. While the fossil record suggests the Great Dying was smeared over at least 150,000 years of time. The next most obvious target would be something not from space but from the earth itself. Volcanic activity has proven to be cataclysmic, but for a volcanic cause to the Permian extinction there would have to have been some unseen magnitudes of it. Enter the Siberian Traps.
This is a large region of volcanic rock in Siberia, Russia. The massive eruptive event that formed the traps is one of the largest known volcanic mass eruptions that has occurred on earth in the last 500 million years. Eruptions here continued for over 2 million years and were right on top of the Permian.
252 million years ago a giant blob of magma built up beneath the Siberian crust. The number of volcanoes at the time must have been insufficient to vent the heat and pressure as the entire crust would begin to bulge upwards until it cracked. The resulting magma eruption was unseen in the Earth's history. The entire landscape would have erupted and turned into a sea of lava.
Everything alive right there would have been incinerated instantly. An eruption like this is called the Basalt Flood and involves the landscape being covered in molten rock. The Siberian traps released enough lava to cover an area the size of the mainland United States beneath a kilometer of molten rock.
Besides lava, volcanoes release lots of ash and gases. The ash will cover a much larger area than the lava being released into the atmosphere and snowing down upon the surrounding area. For regular volcanic eruptions this can be to hundreds of kilometers from the volcano. In case of the Siberian eruptions this was global.
Worldwide it snowed volcanic ash. The hot toxic snow burned and killed the plants. The gases released made it even worse than it already was.
Much sulfur and carbon dioxide was released by the eruption. Sulfur dioxide mixed with water in the atmosphere forms acid rain. The volcanic ash and acid rain spelled doom for the vegetation on Earth. Dying plants meant starving plant eaters and the carnivores that eat them.
At this point 10% of the Earth's biodiversity was already gone. But the collapse of the food chain was only the beginning of the greatest mass extinction the Earth has ever seen. Not all the gas. came down back on earth as acid rain. Most of the carbon dioxide stayed in the atmosphere.
As we all know, carbon dioxide is a big bad greenhouse gas. Global warming due to carbon dioxide release, is naturally kept in check by plants absorbing the CO2 back from the atmosphere. But the plants were dying globally and the carbon dioxide levels surged. It's estimated that the carbon dioxide levels in the atmosphere during the eruptions were 20 times higher than today. Post-industrial 400 parts per million that is.
So 2000 parts per million. of carbon dioxide in the atmosphere. It wasn't before long that temperatures began to rise due to this.
At this large concentrations of carbon dioxide global warming goes wild. In a very short amount of time the temperature rose by as much as five degrees. Five degrees may not sound as much to us but it was absolutely devastating to the earth's biosphere.
Most biomes were completely shifted if not destroyed at all by it. At this point extinction rates rose to 40% But it got worse even still. The rise in temperatures warmed the oceans Marine life is even more sensitive to temperature changes than terrestrial fauna. The warmer atmosphere stripped the oceans of oxygen. Most of the oceans became stagnant and pretty much everything except algae died coral reefs Tridobites, predators, everything was gone.
And in the new oxygen deprived oceans, anaerobic bacteria such as pink algae took over. The anaerobic bacteria that took over released hydrogen sulfide into the oceans. As a consequence the oceans would turn pink due to this gas being released.
And during the Permian extinction a look at earth from space would have revealed a rare view of shallow pinkish seas. CO2 the best deposited on the ocean floors was released as a minor runaway greenhouse effect started to take action on Earth. On the ocean floor methane hydrate deposits, which are a frozen form of methane stored at the ocean floor, got released due to the warmer water. Methanhydrate is a really interesting molecule where hydrates have encapsulated methane within a crystal structure of water, forming a solid similar to ice, methane ice, because it still contains methane.
And methane is a greenhouse gas too, at least 20 times deadlier than carbon dioxide. And the warmer water in the oceans caused the crystal capsule around the methane to defreeze, releasing the methane into the atmosphere. This caused the temperature to rise another 6 degrees. An 11 degree rise in the earth's temperature was cataclysmic for species on earth. The Earth was now 42 degrees on average, where the temperature finally stopped rising.
Unable to adapt to the temperature rise, 93% of life on Earth ceased to exist. With 42 degrees, Earth had also come on the verge of a runaway greenhouse effect. For people who have seen my What Went Wrong on Venus video, you know how disastrous this would have been.
And knowing we came only 5 degrees short of triggering it on Earth, is something to think about in a new, hot, desolate world that remained, only a few animals survived, by scavenging everything left and hiding underground. Further, everything else was dead. The Siberian eruptions continued for 500,000 years, spewing out lava, ash and gases. And when they eventually finally stopped, it took the earth 2 million years to recover and temperatures to return to slightly normal.
For vegetation to return it took about 5 million years. and for biodiversity to recover it took about 10 million. From the surviving species, in the following Triassic period, arose the dinosaurs as the new dominant species on the planet.
And that's how the Earth's greatest mass extinction 252 million years ago happened. A 500,000 year long basalt flood that put in motion a chain of events that spelled doom for species on earth at the time.