Permian Mass Extinction
Mass extinctions occur due to various reasons and conditions of the earth. Extinctions may seem tragic and as a loss of biodiversity, but shapes the future of the biodiversity of the earth. As far as earth’s recorded history, there have been five mass extinctions, and of the five, the most mass extinction rate was the Permian Mass extinction. During that extinction 96% of species perished, and of the species alive on earth today, evolved from the surviving 4%. The worst hit groups were those that were attached to the sea floor, nourished by filtering organic material from seawater. There are many reasons that contributed to this mass extinction, and the lives that were impacted, and will attempt to explain how it unfolded.
The Permian period lasted about 52 million years, 250 million years ago, and during a brief geological time period, the life created was almost completely wiped out. There are a few theories as to what caused this mass extinction, severe volcanism, a nearby supernova, environmental changes wrought by the formation of a super-continent, the devastating impact of a large asteroid — or some combination of these. The severe volcanism was in the area of present-day Siberia, and the massive eruption could have caused depletion of oxygen, as scientists mention there to be a drastic decrease causing instability of the organisms’ lives. The effects described above rely on evidence from recent eruptions, but flood-basalt eruptions like those in Siberia were orders of magnitude larger than anything known from the historical record. Other effects of this severe volcanism would have had is scorched vast expanses of land, clouded the atmosphere with dust, and released climate-altering greenhouse gases. The dust could also cause plants that relied on photosynthesis to diminish their processes, thus causing them to die because of low availability of the sun’s energy through obscuring it. That same atmospheric debris could have cause the ocean life to die due to deep-sea anoxia. Oxygen depletion also relies heavily on temperature and at higher temperatures, there is less oxygen dissolved in seawater. A research team who discovered sulfur isotopes in a region of a Permian-Triassic boundary layer supports the theory that a large outer space asteroid collided with the earth. This would suggest that the material came from the planet’s mantle and was released spread material over the surface of the earth. Aside from short-term global warming, the kill mechanisms associated with large methane flux, be it from marine clathrates or Siberian coals, are unlikely to differ much from those associated with elevated carbon dioxide, as methane in the atmosphere would oxidize to CO2 on a timescale of decades. Such possibilities include global warming, hypercapnic stress, and the facilitation of marine anoxia.
When we learn of historical mass extinctions, it is not difficult to compare to the one we may potentially already be a part of, and as humans, we can not guarantee the stability of the earth for long periods, we know the inevitability of such catastrophic mass extinctions is feasible at any time period, and the extinction of homo sapiens is likely possible.