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.