Mass Extinction Definition
A mass extinction is a massive and relatively sudden decrease in the biodiversity of life on Earth. It is this decrease in the abundance and diversity of living organisms that marks and identifies an extinction event.
The abundance, or super-abundance, of life and the sudden disappearence of life is cyclical. There have been major extinction events, and many more minor extinction events.
Nemesis is the name given to a hypothetical red or brown dwarf star, which is said to be orbiting our Sun at a distance of 1.5 lightyears.
Originally put forward in a 1984 scientific paper, the authors of the paper used statistical methods to determine that the average time between mass extinctions was around 26 million years. This has come to be known as the Nemesis or Death Star hypothesis.
This hypothesis is a possible explanation for these occurrences. It is known that stars sometimes form in a binary system (although we now know that this is rarer than it was believed at the time of publication), and so they put forward the idea that another star was orbiting our own in a highly elliptical orbit. Once every 26 million years or so, this disturbs comets in the Oort cloud, which increases the likelihood of an impact on our own planet.
In the subsequent decades, there has been no evidence showing that this star exists, even while data of surrounding stars and star systems has increased exponentially since the time of publication. However, another study from 2010 confirmed the earlier works assertion that there was a periodic mass extinction, and updated that interval to be about 27 million years.
5 Massive Extinctions
- Permian Triassic Extinction, a.k.a “The Great Dying” | 252 million years ago; 90-96% of all species extinct (96% of marine species, 70% of land species, including insects).
- Cretaceous Extinction | 66 million years ago; 75% of all species extinct.
- Triassic Jurassic Extinction | 201.3 million years ago; 70-75% of all species extinct.
- Late Devonian Extinction | 360-375 million years ago; more than 70 % of all species extinct.
- Ordovician Extinction | 440-450 million years ago; 60-70% of all species extinct.
The chart shown above tells the story of a climate episode around 12,800 years ago known as the Younger Dryas. The earth was experiencing a gradual warming of average temperatures as the last ice age was beginning to recede. However, during a period of about 2,000 years the planet’s temperatures suddenly plunged to temperatures not seen since the peak of the ice age. What’s fascinating about this time period is that the ocean levels rose rapidly even though the temperatures plunged. Generally, colder temperatures lock sea ice into glaciers and lower ocean levels. Until recently, the reason for this extreme climate event was not known.
Younger Dryas Impact
12,800 years ago a large comet fragmented and hit the earth in at least one location. This impact caused extensive biomass to burn, a brief winter, and extensive climate change.
It is postulated that this is the cause for the extinction of many of the North American megafauna, such as the camel, short-faced bear, and mammoth, which all went extinct around this time. It is also believed that this event sent human civilization into chaos, and scattered human beings around the globe. This idea competes directly with the prevailing narrative that humans hunted megafauna to extinction.
The idea of a massive comet hitting the earth has been around for at least hundreds of years, if not longer. It is speculated that many of the events depicted in the bible were in fact caused by comets. If the Younger Dryas Impact Theory is to be believed, that means humans survived massive environmental changes, including worldwide floods and an acute and prolonged winter. The theory illuminates why there are flood myths in religious traditions from around the world.
While this theory has been around for decades, in recent years, the evidence supporting it has been growing. In 2018 an impact site was found under 1-mile thick permafrost in Greenland. Many theorize the impact crater corresponds to the Younger Dryas climate episode.
While providing an explanation for the massive burning of biomass dated to around the same time. There have also been Platinum and other deposits found around the world in sediment layers. This points to a large impact powerful enough to send pieces of debris, in measurable amounts, around the world. The impact would have also melted the North American ice cap leading to rapid sealevel rise.
One potential source for a planet-wide mass extinction in the future is the Yellowstone Supervolcano.
Located in the northwest corner of Wyoming, the Yellowstone Caldera measures 34 x 45 miles, while the underground magma chamber measures 50 miles long by 12 miles wide. This underground chamber has a volume of 960 million cubic miles, which is filled at about 7% of capacity with liquid magma.
Relatively young in a geologic sense, this volcanic hot spot has produced 3 supereruptions over the years; 2.1 million years, 1.3 million years, and 680,000 years ago. There have been many other minor explosions and eruptions before and since those times. This has resulted in over 20 craters being formed in the last 14,000 years alone; the most recent of which occurred around 1300 BC.
Home to thousands of (relatively minor) earthquakes every year, the Yellowstone Caldera is still geologically active. Visitors to Yellowstone National Park can visit geysers such as Old Faithful and watch this in action. A geyser is a surface vent for subterranean boiling pressurized water, essentially a spring with a forceful and spectacular display as the water and steam enters the air.
It’s also worth mentioning that the Wild West Trail charts a course directly through the park. What are you doing next summer?