We all have noticed that planet earth is home to a startling array of animals, both big and small. Lift a rock, climb a tree, secure your head into a lake, spelunk your way into a case, wherever you look life teams. But here is a mind-blowing random interesting fact for you. Despite the remarkable abundance of life all around us, it turns out that an estimated 99.9% of all the animal species that have ever existed on earth have already gone extinct. Yes, gone extinct!! this extinction could be considered the great dying leading to the death of around 95% of living things.
Just as death is a normal part of life, extinction is a normal part of evolution. The quietest slipping away of species over time is known as the Background Extinction Rate. It changes from one epoch to the next, but it is always there, no matter how good conditions are for life. Not all species loss is like the proverbial tortoise, slow and steady.
Every once in a while the extinction hair rocks off and starts gunning down unsuspected species faster than legless killing gross at the battle of Helms. These so-called mass extinctions have occurred a total of five times in the history of our planet. No doubt you have heard of at least one of them, ‘The Cretaceous Paleogene Extinction Event,’ that wiped out the dinosaurs 66 million years ago. That is an undeniably a-list celebrity amongst extinction events. It was not the deadliest- not by a longshot. That title belongs to a cataclysm so terrible, it came within a whisker of wiping out complex life on earth.
The Great Dying
Today scientists call this catastrophe the ‘Permian Triassic Extinction Event’. But it is also known by another much more fitting name, The Great Dying. It was quite simply the biggest natural disaster in the history of life on earth. The Great Dying took place approximately 252 million years ago, and it was almost imaginably deadly.
When the dinosaurs game over screen arrived on the surface of a 10-kilometer wide asteroid that smashed into the Yucatan peninsula with the force of 100 billion atomic bombs 66 million years ago, 50% of all animal species on earth at the time were deleted from existence. Now, it is hard to imagine something more destructive than an asteroid strike, but during The Great Dying, a staggering 90% of all species were eliminated, apocalyptic does not even cover it. Never before or since has complex life been so close to disappearing entirely.
So, here’s the million-dollar question?
If a giant asteroid smashing into the planet only killed off half of life on earth, what the hell happened 252 million years ago to do away with almost all of it.
The truth is nobody knows for sure. 250 million years ago is a very very long time, and much of the evidence we would need to reach definitive conclusions have long since disappeared. Trying to figure out the identity of the ruthless killer that initiated the great dying is basically like investigating the oldest cold case on earth. Luckily, like the good intellectual detectives, they are a bunch of scientists who have spent the last few decades doing exactly that.
Between them, they have pieced together a pretty compelling case for the prosecution of this most massive of mass murderers. One not only explains how complex life nearly ended during the great dying, but that also has a surprising amount of relevance today 252 million years later.
The Volcanic Eruption- Is It The Mysterious Event
Just before the Permian Triassic extinction event kicked off history’s most brutal bout of species-related spring cleaning, a volcanic eruption took place in what is today Siberia. when you picture an erupting volcano you probably imagine something along the lines of mount St. Helens in 1980, explosive and destructive but relatively short-lived. The volcano that erupted just before the Great Dying was a little bit different.
The eruption of Mount Saint Helens built up to an explosive finale throughout a couple of months. The eruption events that coincided with the great dying lasted for two million years. The Siberian volcano is fortunate to have been caused by a mantle plane, essentially a big blob of unusually hot magma beneath the earth’s crust. About 250 million years ago, this particular mantle plume rose from the belly of our planet and spewed forth its molten plume all over Siberia, like junk after bewildering.
The kind of scale we are talking about here is the Mount St. Helens eruption, which was one of the largest in the entire 20th century. Coughed up about 2.8 square kilometers of material. The volcanic events that took place in Siberia in the lead-up to the Great Dying brought forth 4,000,000 cubic kilometers of material from the depths of the earth. That’s enough lava to cover the entire planet in a layer 8 meters deep.
That’s a lot of molten rock.
These eruptions represent one of the largest volcanic events ever to have taken place on earth, but it wasn’t the eruption itself that almost wiped complex life out of existence, or at least not directly. Whilst in theory this supervolcano produced enough lava to form a planet-wide ocean of molten death, in practice that lava was confined to an area of seven million square kilometers in Siberia known as the Siberian traps. It still is there today.
A vast landscape, the size of Australia built on lava fields hundreds of meters deep and over 250 million years old. But, no it wasn’t lava death that caused the Great Dying. it was the resulting chain reaction that quickly snowballed into a real-life version of the apocalypse.
What Are The Causes of The Great Dying
It started the same way your last beans on toast dinner and ended with some really bad gas. Whilst we tend to focus on the more exciting parts of volcanic eruptions, the lava, the pyroclastic flows, the holiday hampering ash clouds. Volcanoes also produced an awful lot of gas, which include water vapor which is, of course, harmless, but also CO2 and sulfur dioxide, which very much aren’t harmless. As trillions of tons of lava oozed up, out of the earth in Siberia, 250 million years ago, vast quantities of sulfur dioxide dust and ash billowed up into the atmosphere, blocking out the sun and resulting in the rise of global temperatures.
The resulting reduction in sunlight caused massive disruption to photosynthesis in both the oceans and on land. Since the organisms found at the bottom of most food chains are photosynthesizers like plants and algae, this sudden dip in production caused food chains to collapse, and devastate ecosystems across the globe. What goes up must come down. And eventually, all that debris fell back down to earth, dust and ash blanketed the ground and choked the air, and the sulfur dioxide which had combined with water vapor to form acid aerosols was washed out of the atmosphere in the form of some of the most severe acid rain ever experienced on earth.
This deadly precipitation got to work murdering whatever planned life was still left alive. Whilst also contributing to a significant drop in the pH of the oceans. Enough to crumble carols and melt the shells of other sea creatures, clean off their backs.
Then it was about time that this other volcanic gas, carbon dioxide joined the party. As you have probably noticed that CO2 is a potent greenhouse gas and once the dust cloud settled and the acid aerosols had dissipated, all that extra CO2 in the atmosphere began to do its thing. Leading to an intense period of global warming. The warming was made even worse by a monumental stroke of bad luck.
The Siberian traps happened to be located on top of an extensive coal bed, as rampaging lava ignited these coal beds on an enormous scale, catastrophic levels of greenhouse gases including carbon dioxide and methane were released into the atmosphere. Estimates vary wildly, but by some measures, it is thought that the Siberian trap’s eruptions contributed to the release of some 14.5 trillion tonnes of carbon, about 2.5 times what would be released if we burned all the fossil fuels on earth. At the same time, as a result, global atmospheric temperatures shut up by as much as 8 degrees Celsius.
Scientists today expect some fairly dire consequences if we allow global temperatures to increase just two degrees above pre-industrial levels. 8 degrees is practically unthinkable. And it wasn’t just the air that was getting uncomfortably warm, the seas were too. With water temperatures reaching more than 40 degrees Celsius at the equator. That’s about the temperature of a hot tub, which sounds kind of nice but remember this particular hot tub was full of skin melting acid and trillions of dead animals.
How did the Death of Plants and Animals Cause The Great Dying?
When you start laying it all out like this, it’s kind of surprising that anything managed to survive the Great Dying at all, and the real-life hellscape is not painted yet. With plants and forests utterly decimated and acid rain pouring from the skies all over the world, far more bare earth was exposed to the elements than was normal, and so erosion skyrocketed washing massive nutrients into rivers and oceans.
That might sound like a good thing, and it was for a bit. The nutrients triggered a brief but pronounced explosion of life but when that life inevitably died away, thanks to the increasingly inhospitable conditions. It sank back into the ocean depths where the bacteria that fed on it, suddenly found themselves as guests of honor on the biggest buffet on earth. As this bacteria proliferated, it hoovered up oxygen like a dedicated smoker after a triathlon. Combined with the fact that oxygen is less soluble in seawater at higher temperatures, this led to a huge reduction in ocean oxygen levels all around the world.
Between this lack of oxygen and rising acidity from acid rain and elevated CO2 levels in the atmosphere, the earth’s oceans became very nearly uninhabitable. It is estimated that around 96% of all ocean-dwelling species died out.
How did The Great Dying Unfold?
Nobody knows quite how long it took this nightmarish process to unfold. Early research suggested it might have been some 15 million years or so. But, recent evidence points to a far more rapid decline, perhaps just a few 10s of thousands of years. However long it took, everyone agrees that when it was over, life on earth had been all but annihilated.
It is hard to get your hands on some good rock samples that span the Permian Triassic extinction. Much of it is either long since weathered away or buried deep beneath the ground. But the examples we do have to tell a pretty bleak story, with fossil diversity simply disappearing at the boundary line, even more creepily, we also see a huge spike in fungal fossils, around the time of the extinction. Presumably, because various fungi were having a great time, chowing down on all the dead plants and animals lying around everywhere.
Of course, not everything succumbs to the Great Dying, a few incredibly tenacious species managed to adapt to the almost unimaginable hostile conditions. One plucky Beasty that made its way through this storm was lytrosaurus, a proto mammal that was a bit like a cross between a lizard and a pig.
Let me know your opinion about this mass extinction and the mysterious event behind it.