The History of Earth's 5 Mass Extinctions

     Detailed in Elizabeth Kolbert's book, The Sixth Extinction, an Unnatural History, there is evidence of 5 natural mass extinctions that destroyed the majority of biodiversity on the planet. Her book primarily is focused on how humans as a species have put the Earth into a period of a sixth mass extinction, slowly but surly killing biodiversity of our planet and our planet as a whole. However, that is not to say she undermines how powerful and important the previous 5 mass extinctions were.

    Ordovician: 440 million years ago. 86% of species lost.
Killing about 86% of all species, this was the second most brutal to biodiversity at the time. All life was sea creatures, so when a sudden lack of CO2 in the atmosphere comes from growing mountains and a lowering of the sea level. With no CO2, an ice age occurred.

    Devonian: 350 million years ago. 75% of species lost.
At this point in time the majority of life were still ocean creatures. However, plants were now abundant on land. The plants that grew along the coast ended up spilling nutrients into the oceans which caused the evolution of different algae. This algae sucked up the oxygen in the oceans which lead to many species suffocating.

     Permian: 250 million years ago. 96% of species lost.
The most devastating to biodiversity on the planet with 96% of species becoming extinct, the Permian era mass extinction is one that gets compared to the sixth extinction numerous times in Kolbert's book, as what killed most of these species can be attributed to climate change. Due to a combination of volcanic eruptions and freak weather patterns, the greenhouse gasses that were emitted into the environment were too great for most species to handle. Causing a global climate change and catastrophe for most life.

     Triassic: 200 million years ago. 80% of species lost.
No clear cut cause for this extinction has been confirmed by scientists. However many speculate that it was a series of different extinctions from changing weather patterns, to more greenhouse gas emissions, and a loss of habitat and food for the species on Earth.

     Cretaceous: 65 million years ago. 76% of species lost.
While creatures of this era were already under great stress due to climate change, a giant impact from an asteroid is what ultimately did in the dinosaurs and many other species in. After the impact, a blocking out of the sun in a state similar to that of a "nuclear winter". The only survivors are what deviated to form into all species that roam the Earth today.

     Humans need to take a look at the history of the world and realize what could happen if we as a species continue down the slippery slope we are already on.

-Wainam