Mass Extinction Handbook – WIF Science

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Facts about the Earth’s

Greatest Mass Extinction

Their causes are somewhat varied, but we’ll be focusing on the greatest mass extinction that has ever taken place here on Earth. It happened some 252 million years ago, during the Permian period, and paved the way for the Triassic one. Also known as The Great Dying, the planet witnessed a huge cataclysmic event, so devastating that 75% of all land creatures and over 95% of all marine life went extinct. What caused it, what exactly happened and what can we learn from it, we’ll be discussing in this article down below.

10. The Permian Period


In order to properly understand what happened back then, we first need to look at the Permian period itself. It lasted for about 47 million years, from 299, up until 252 million years ago and was part of the larger, Paleozoic Era. By the beginning of this period, all current continents were pushed together and formed a single large super continent, known as Pangaea. Life in the interior of this huge continent was harsh, as it had a much cooler, drier climate than around its coast. Fern-like plants and forests, which dominated the previous Carboniferous period, began to give way to the first seed-bearing plants, the gymnosperms, which in turn evolved to present-day conifers, cycads and gingkoes.

Two types of land animals began to evolve during this time, the Synapsids and Sauropsids. The first, which seemed to be the dominant of the two, or at least at the beginning, were the ancestors of all present-day mammals. In the later part of the Permian period, these evolved into the Therapsids, with some of them exhibiting evidence of whiskers and a possible indication of fur.Sauropsids on the other hand, went on to become the reptiles, birds and dinosaurs that would follow the Permian. Insects began to diversify, with cicadas and beetles making their appearance at this time.

Marine life is a bit harder to identify as there is little exposed fossil evidence available. Nevertheless, the shallower coastal waters around Pangaea indicate that reefs were large and diverse ecosystems with numerous sponge and coral species. Bony fish began to make their presence felt, while sharks and rays continued to multiply as they’ve done for millennia. Life in all its prehistoric shapes and sizes seemed to be stable, with evolution following its normal path. But then something happened; something that would shake the entire course of evolution from its very core.

9. A Massive, Earth-shaking Eruption


Many have speculated that the trigger for all these species to simply die off was a meteorite slamming into the Earth, similar to the one that may have wiped off the dinosaurs millions of years later. According to the evidence however, this seems to not have been the case. Since fossil records don’t indicate a sudden and all round extinction (like the one you would see with an asteroid impact), paleontologists have come to the conclusion that something else was the cause. And that cause can still be seen today in modern-day Siberia.

Hidden beneath the Arctic tundra, lies one of the world’s largest expanse of lava flows, forming a bleak landscape known as the Siberian Traps. What happened back then can only be described as a huge supervolcanic eruption, the likes of which have not been seen on Earth for over 500 million years. During the Permian period, Siberia was located at the northern part of Pangaea and when the volcano erupted, it engulfed an area roughly the size of the US (almost 1.7 million sq. miles) in a one mile deep sea of molten rock. Today only about 500,000 sq. miles of it are still visible. The type of lava found here indicates that there wasn’t a big explosion (but given its size, it was huge compared to ordinary volcanoes), but rather a prolonged flow of basaltic lava which spread for millions of sq. miles, in a process which maybe lasted for 500,000 years or more.

And now, even if these immense lava flows may have killed anything in their path over a large area of land, it still doesn’t account for the greatest mass extinction in Earth’s history. What came after it however, managed to do the job.

8. First Came Acid Rain


Besides the tremendous amounts of ash and dust that came from an eruption such as this, there was also a huge quantity of sulfur dioxide; a gas that has a huge negative impact on the environment. This gas rose high up into the atmosphere where it condensed into tiny droplets. If mixed with water however, you get sulfuric acid. It is estimated that the air in the northern hemisphere of this ancient Earth had a pH level so low, it was comparable to undiluted lemon juice in its acidity. Research shows that within the first year after the eruption, the volcano was able to produce about 1.46 billion tons of sulfur dioxide, enough to completely devastate the northern half of the world. Around 4,000 billion tons of sulfur dioxide may have escaped Siberia in total.

Back in 1783, Iceland witnessed one such similar volcano and subsequent lava flows (but incomparable in size), around Mount Laki. After the eruption people reported their eyes burning, impossibility of breathing, livestock suffocating and suffering lesions and burning of their skin, with plant life getting the worst of it. The same thing happened 252 million years ago, but at a much, much larger scale. The whole food chain began to collapse as acid rain was burning plants and animals alike. These toxic gases also created some chemical reactions that destroyed the overall protective ozone layer to levels lower than those observed in the Antarctic ozone hole in the 1990’s.

7. Then Came a Volcanic Winter


After a while these acid rains began to stop, but not all sulfur dioxide managed to be washed off from the air. Some of it remained high in the atmosphere, way above rain-forming clouds, and as minute sulfuric acid droplets. These reflected sunlight away from the planet, cooling its surface. Together with the insane amounts of ash and dust which quickly encircled the globe by high stratospheric winds, the planet began to witness an abrupt drop in all-round temperatures. The same thing happened in Iceland in 1783. Here the cooling was catastrophic as it killed more people than the acid rain and volcano combined. For a period of two or three years, much of Northern Europe reported crop failures, death and unrest as a result. The infamous French Revolution started because of it.

In a virtual simulation made on the last eruption at Yellowstone, some 640,000 years ago, ash and dust completely covered the northern hemisphere in just one month’s time and dropped temperatures in 18 months by 10 degrees Celsius. This blanket brought on a quick rise in Arctic ice, reflecting even more of the sun back into space. Rain stopped falling altogether with the oceans and land retaining more CO2. This made food supplies last for only weeks in some areas. It took the planet about 20 years to come back to its pre-eruption temperature. But our eruption from 252 million years ago was 1,600 times larger than this one and lasted for over half a million years. The winter itself certainly didn’t last as long, but it most certainly sent global temperatures plummeting for decades if not centuries. With the food chain in disarray, 10% of the world’s species had perished by this point.

6. Quickly Followed by a Massive Global Warming


All the while the dust settled, our supervolcano continued on pumping lava over the landscape, as well as tons upon tons of CO2 into the air. Fossil records from the time following the eruption indicate a sudden rise of carbon in the atmosphere. Scientists calculate that CO2 levels during the eruption were 20 times higher than they are today, and more than enough to seriously affect the planet. It was a sort of global warming on steroids. In 10,000 years the volcano released 24,000 gigatons of carbon into the atmosphere and temperatures spiked by more than 5 degrees Celsius. However much 24,000 gigatons sound, if divided by the time it took to be released, it comes down to only 2.4 gigatons per year. We currently emit slightly over 4 times that (about 10 gigatons), with even more being foreseen to be pumped in the future.

While this 5 degree increase doesn’t seem that much to us, it has some seriously devastating effects on the climate. In equatorial regions it simply stopped raining and lush forests quickly became scorched deserts. If these regions were least affected by the previous volcanic winter, the massive global warming that followed severely changed that. This is the moment in time when the last of the Permian herbivores like the Dicynodon, as well as 35% of all land life, perish. And if things looked like they couldn’t get any worse, they did. This “rapid” global warming unleashed a deadly chain reaction, but this time in the oceans.

5. Leading to the Oceans Turning to Acid from Above


All the while extinction ruled over the land above the surface, nature was brewing an even more atrocious fate for the oceans. Life here remained mostly unscathed by the previous apocalyptic events, but things were about to take a turn for the worse; much, much worse. All throughout this time, the oceans were absorbing about half of the CO2 from the air (similar to what it’s doing today). Scientists have deduced that, over the course of the previously mentioned 10,000 years during the eruption, the pH levels in the oceans dropped by 0.6 to 0.7 units. In comparison, modern ocean pH levels have fallen by 0.1 pH units since the Industrial Revolution, a 30 percent increase in acidity. Depending on the future trend of carbon dioxide emissions, this value could fall by another 0.3 to 0.4 units by the end of this century, which will bring us extremely close to what happened 252 million years ago.

And what happened was disastrous for all marine life. As CO2 combines with water, it turns into carbonic acid. In seawater, this acid can have some really negative effects on the formation of carbonate minerals; the ones that mussels, corals, sea urchins and plankton use to make their shells. As acidity grew, these marine species died off and with them the whole marine food chain system collapsed. Scorpion-like predators called Eurypterids, to various types of Trilobites as well as all shell-forming beings died off because of this event. Some other less resistant marine species were also extinguished. Matthew Clarkson, a geochemist at the University of Otago in New Zealand said that it took life another 5 million years to diversify once more.

4. And Oxygen-depleted from Below


As marine life was being killed by the growing water acidity, an equally devastating killer was rising from the depths. With temperatures surging worldwide, so did the water. This in turn led to the oxygen-depleted watersfrom the ocean floor to expand and rise to the surface. Not being allowed to sink to larger depths due to suffocation, fish and invertebrates were stuck between a “rock and a hard place”, dying en masse as a result. Evidence of thiswas found in Greenland, by paleontologist Paul Wignall from the University of Leeds, where the ancient seabed, now raised, show signs of a large amount of fool’s gold (pyrite). This element can only be created if there is no oxygen around.

Evidence of this rising, oxygen-depleted, water can be seen today. As the oceans warm up, less oxygen is carried in the water, thus leaving the ocean sequestered in layers. Already naturally low in oxygen, these deep regions keep growing, spreading horizontally and vertically. Vast portions of the eastern Pacific, almost all of the Bay of Bengal, parts near Central America, and an area of the Atlantic off West Africa as broad as the United States are such “dead zones”. Since 1965, these low-oxygen areas have expanded by more than 1.7 million square miles. Further studies have indicated that during the Permian extinction, this low oxygen in the water has halted recovery in the oceans by at least one million years.

3. With Water Turning Pink and Poisonous as a Result


Besides no oxygen, fool’s gold also needs hydrogen sulfide (H2S) to be produced. And according to the large amounts of it found all over the world, and dating from that period, it is evident that the oceans were full of the stuff. In order to get that much H2S into the water however, something drastic must have happened. As temperatures rose, ocean currents stopped and water became low in oxygen. Once this occurred, organisms which hate oxygen began to thrive. The purple sulfur bacteria is one such organism. Often found in stagnant water, these bacteria have a waste product (H2S) which is poisonous to all air-breathing life. With the rise of oxygen-depleted waters, so did the environment for this organism grew, resulting in poisoning of the entire Permian ocean.

There was so much H2S in the water, that, if seen from space, the ocean would have looked pink in areas where it now looks green, due to the large number of bacteria present. But besides its aesthetics, some scientists believe that there was so much toxic gas produced, it could no longer be contained in seawater solution. As a result, large oily bubbles of hydrogen sulfide came out of the pink-stained sea and entered the atmosphere with some truly devastating results. Besides poisoning the few remaining plants and animals at the surface, H2S also significantly added to the shrinking of the ozone layer, left behind by the sulfur dioxide from the eruption.

2. And Then Came the Final Blow


At this point in time, almost all marine life was gone. It was the closest our planet ever came to achieving an aquatic extinction such as this. Land life on the other hand was only halfway there. What caused the other 25% to die was another subsequent heat wave. This time however, it didn’t come from the volcano itself, but rather from the depths of the ocean. And CO2 wasn’t to blame this time either, but rather methane.

Methane is 25 times more potent as a greenhouse gas than CO2, and there is currently an estimated of 30 trillion tons of methane hydrate locked on the ocean floor. If for any reason, water temperatures rise, this methane is released, as it is ultrasensitive to heat, and flows to the surface in the form of bubbles. This in turn will heat up the planet even further, leading to even more methane escaping, in a sort of a positive feedback cycle. This is exactly what happened 252 million years ago, killing off the remainder of land animals and plants, “fortunate” enough to escape the previous cataclysms. Earth’s temperature rose by another 5 degrees Celsius as a result.

Even if it took the Siberian Traps more than 10,000 years to reach this point, we today have begun to experience this phenomenon. As of 2014, researchers have found more than 500 bubbling methane vents being activated off the US east coast alone. There are an estimated 30,000 other such hidden methane vents worldwide. While this methane doesn’t reach the surface yet, it is however dissolved into the ocean at depths of hundreds of meters and being oxidized to CO2, which leads to further acidification of the water.

1. The Aftermath


Huge catastrophes such as this one can reset the evolutionary clock, meaning that the whole course of evolution will change. As the dominant species disappear, less significant ones take their place. As Gorgonopsians died off due to the scorching heat and hunger, the smaller Cynodonts took their place. Since these creatures burrowed underground, it offered them protection from both their dying predators as well as the harsh climate outside. After the mass extinction was over, and over the course of millions upon millions of years, these Cynodonts went on to become one of the dominant species of the new world. Without them we, as well as all other mammals, wouldn’t be here today.

Thoroughly understanding what happened during the end of the Permian, can help us tremendously in dealing with our current Anthropogenic Extinction. As we have observed up to this point, we are presently experiencing many of the effects felt millions of years ago, but which take place at a much faster pace than they did back then. For the first time in Earth’s history, the dominant species on the planet is upsetting the delicate balance of its ecosystem. Our massive production of CO2 has a catastrophic impact on Earth’s systems and we are able to shorten the time from tens of thousands of years, to mere centuries… some of which have already passed.

Many will say that this is just a way for the planet to “reboot” itself in terms of life. It happened before so it can happen again, right? Well, not necessarily. While it is true that we are the result of this Permian extinction, as well as the others that followed, this doesn’t automatically mean that life will happen again if Earth goes through another massive die-off. Venus is one such example. Even if it never had life, at one point in its evolution, these two planets were quite similar. But since Venus is closer to the Sun, it was a bit warmer. Because of this, our sister planet went through a process known as a runaway global warming, which made it into the hellish place it is today. Its closer proximity to the Sun was just the catalyst needed to ignite this global warming which, after 4 billion years, is still going on. Are we really that proud as to put all life we currently know exists into such a dangerous and risky predicament?

Mass Extinction Handbook

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– WIF Science

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