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By Robert A. Vella

Author Elizabeth Kolbert coined the phrase “The Sixth Extinction” in 2014 with her shocking nonfiction book on catastrophic climate change.  It details the anthropogenic (i.e. man-made) mass extinction event now transpiring on our planet, initially and primarily in the world’s oceans.  And, this unfolding story of environmental destruction can be told by examining two previous mass extinctions in Earth’s history, the Permian-Triassic event of 250 million years ago and the K-T event of 65 million years ago which killed off the dinosaurs.

The second, and more popularly-known event, is widely attributed to the sudden impact of a large asteroid in the Yucatán Peninsula of Mexico(see: Chicxulub crater) which ejected huge quantities of debris into the atmosphere.  Most of this ejecta immediately fell back to earth causing a massive atmospheric heat pulse sufficiently intense to kill virtually all large organisms unable to shelter themselves.  The toxic gases and dust remained in the atmosphere for an extended period blocking out sunlight and triggering the equivalent of a nuclear winter which shutdown photosynthesis and disrupted the food chain.  Roughly 75% of all plant and animal species went extinct.

The first event was an even bigger calamity for life on Earth, but it is generally attributed to a completely different cause and to producing a completely different extinction mechanism.  Leading hypotheses on the Permian extinction (a.k.a. “The Great Dying”) indicate large scale volcanism (see:  Siberian Traps) which triggered a runaway greenhouse effect (i.e. catastrophic climate change) that acidified Earth’s oceans (see Anoxia) eventually to the point where 96% of all marine species went extinct.  Unlike the K-T event which occurred over a relatively brief span of time and which struck large organisms hardest, the Permian extinction transpired over tens of millions of years and affected a much broader range of species.

The current mass extinction is reflecting both scenarios.  Over-fishing and industrial pollution are damaging marine ecosystems upon which large organisms are most dependent.  This die-off of the big creatures is analogous to what happened to the dinosaurs 65 million years ago.  Concurrently, although at a slower pace, the world’s oceans are warming up and acidifying like they did 250 million years ago due to climate change.

Further reading:  What the ‘sixth extinction’ will look like in the oceans: The largest species die off first

Related story:  U.S. joins more than 20 countries in an effort to mitigate climate change by establishing 40 new marine sanctuaries

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10 thoughts on “‘The Sixth Extinction’ now afflicting our oceans is an unfolding story told by two previous mass extinctions

  1. I am saddened by the thought of how much that once was , is not any longer. I would have loved to at least had some time to marvel at life forms I might not even be able to imagine.

    To the idea that as a species we will die out. Very possible. Although short we have changed the environment more than many creatures that “reigned” millions of years. However even if our species dies out, a representative of our planet will arise and maybe they will one day reach the stars we never did.

    While reading this post I got day dreaming of the asteroid hit in the Yucatán Peninsula of Mexico. I was imagining being able to watch the impact. I was not think of the debris so much as the water. Think of the water displacement. Some would have turned to steam or some type of vapor, some would have raced out as a huge wave. I wonder how the animation would look, would the area be empty of water for a length of time, would the water rush back in and at what speed? How would it effect the waters of the oceans. Would the water level world wide suddenly drop, and if so what about coastal lands? My imagination falters trying to understand it all. Hugs

    Liked by 1 person

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