The mass extinction that gets attention always seems to be the one that brought down the dinosaurs, but it had nothing on an extinction event that made nuclear explosions look like nothing and happened millions of years before a dinosaur so much as appeared.
Earth’s most devastating mass extinction was not triggered by an asteroid. How the End-Permian Mass Extinction or the Great Dying happened 540 million years ago is known, but the enduring mystery was what caused those phenomena to begin with. Now Northern Arizona University’s Laura Wasylenki and her team of researchers have unearthed evidence of the “kill mechanism” that wiped out 96% of marine and 75% of terrestrial species. This extinction was apparently set into motion in Siberia up to 300,000 years earlier.
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“The Siberian Traps large igneous province (STLIP) is widely hypothesized to have been the primary trigger for the environmental catastrophe,” Wasylenki said in a study recently published in Nature Communications. “The killing mechanisms depended critically on the nature of volatiles ejected during STLIP eruptions.”
Hazardous aerosols released into the atmosphere that would ultimately doom Permian life. These substances were full of nickel isotopes, light enough to float, which were eventually scattered above the entire planet. These isotopes were found to have been released by the eruption that formed the Traps, which is thought to be one of the most monstrous volcanic events ever, with massive lava flows that lasted for decades. Insidious global warming set in. It became difficult for organisms to breathe with the lack of oxygen and overflow of carbon dioxide in the air, while the planet also became more vulnerable to UV radiation.
The Permian creatures above and below are just two of the casualties of the Great Dying, but there was more death in the ocean.
DEA / G. CIGOLINI?/ Getty
Anything that lived in what was then the Panthalassic Ocean especially suffered. This was the one massive ocean that surrounded the Pangean supercontinent, in which isotopes of nickel were deposited by aerosol particles, warping its chemistry. It became infested with methanogenic, or methane-producing, bacteria after the eruption. These bacteria break CO2 down and release methane as a byproduct. Whatever breathed underwater could not get enough oxygen. Metabolisms grew faster as temperatures rose, until the water eventually could not hold enough oxygen for things to survive. The marine ecosystem floundered.
“Several lines of evidence support our interpretation that isotopically light, Ni-rich aerosols came to be a dominant source of Ni input to the Late Permian Panthalassic Ocean,” said Wasylenski, adding that “the melting and degassing of Ni sulphide may have produced [the ions].”
Life unfortunate enough to dwell in the ocean towards the end of the Permian period also suffered from acidification. Around 30% of atmospheric carbon dioxide is absorbed by the ocean, and levels of CO2 were staggering at the time. When CO2 reacts with water, it forms carbonic acid, which easily breaks down into hydrogen and bicarbonate ions. This drives up levels of acidity in the ocean. Drastically increased acidity during the Great Dying took up most of the carbonate ions needed for some animals to build shells. Others, such as fish, end up with a decreased ability to find a habitat and watch out for predators.
Next to the excess heat, high acidity and lack of oxygen, marine life also perished from metal and sulfide poisoning. Terrestrial life may have not had it as harsh—but conditions on land were brutal enough. The greenhouse effect from intense global warming killed off many organisms that literally could not take the heat. So did toxic levels of atmospheric methane. Every plant or animal that vanished put anything which ate it out of food, and entire food chains were disrupted as a result. Most survivors on land and sea fled to other habitats.
Humans can learn from this even though we will probably not face extinction anytime soon. If mass extinctions can strike out of almost nowhere, anthropogenic damage isn’t helping, so we should prevent everything we can, as soon as we can.