Saturday, October 3, 2020

Rebooting with a mass extinction

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Pic credit:

There have been five mass extinction events in Planet Earth's history. The most intense among these was called the Great Dying. No, this wasn't the one that killed all the dinosaurs. The Great Dying occurred approximately 250 million years ago. When atmospheric conditions were quite similar to today and the planet was home to a single super continent that we know as Pangaea.
Before we explore the causes of the Great Dying, let's acknowledge the toll it took over the next 100,000 years. 96% of marine species and almost an equal number of plant species became extinct. This marked the end of the Permian era and the beginning of the Triassic era, which is why this event is called the Permian-Triassic extinction.
Here are the theories proposed to explain the harsh transition between the Permian and the Triassic:

  1. A few super volcanos located in today's Siberia went berserk. Over a period of time, this caused a global warming, with ocean temperatures rising by around 10 deg C. As temperatures rose and the metabolism of marine animals sped up, the warmer waters could not hold enough oxygen for them to survive.The asphyxiating effect was accentuated by the high acidity of the water as well as metal and sulfide poisoning. This is, as of now, the most widely-accepted theory.
  2. An asteroid hit the earth, creating noxious gases, a long-lasting blockage of the sun, a drop in temperature and corrosive acid snow and rain. Even after the clouds cleared, carbon-dioxide from fires and decaying matter led to global warming that lasted for millions of years.
  3. Perhaps the lack of ice caps during the late Permian led to a stagnation of oceanic currents. Without convective currents, anoxic water (anoxia means the lack of oxygen) could have built up. Usually, anoxic water would have remained in the deepest parts of the ocean, but now, it spilled up into shallow water. Even as marine life got smothered, the sea level rose.
    • The lack of oceanic currents might have had another corollary effect. When oceanic bacteria eat organic matter, they expel bicarbonate. Without currents, this collection of bicarbonate grew. Bicarbonate-laden water rose from below, depressurized and dissolved bicarbonate escaped as CO2. The oceans bubbled like a mug of beer.

Each theory is as vivid as it is horrifying. As a complete novice to paleontology, oceanography and evolution, I am proud to parrot the wisdom of scientists operating those realms. And my foray into the past was to attempt to understand our present and make peace with our role in shaping it.

For the first time in Earth's history, it hosts a species that is capable of creating and accelerating chaos. Humans are capable of making materials and products that don't decay, but must be dumped on the planet's surface and oceans. We also have shown remarkable finesse in accelerating the era of global warming, which would have lasted tens of thousands of years, and bringing the planet to the brink of being inhospitable right here, right now. 

If we continue to be foolish and press the nuke button on Mother Nature's forehead, well, we will deserve to perish. But it is heartwarming to know that this planet has seen worse in the past and has recovered without many scars. Perhaps this time around, Nature will evolve species that feed on plastic, concrete and metal alloys just to accelerate the obliteration of our presence. But soon enough - perhaps in a few million years - our devastating presence will become undetectable to the naked eye. Earth will recover. We won't matter. Thank Earth for that.

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