An Extinction Level Event (ELE or mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth or the home planet of a species. More than 99.9 percent of all the life-forms that have ever existed on the Earth have eventually become extinct. The Earth has already sustained five major extinction cycles, in which up to 90 percent of all life-forms vanished from the Earth. The Anthropocene extinction is now regarded as the sixth mass extinction, as in late 2021 the WWF suggested that over a million species could go extinct within a decade in the "largest mass extinction event since the end of the dinosaur age." Therefore, science and technology has to be used to change the fate of humanity.
An ELE is one aspect of eschatology but this will article will not talk about religious beliefs such as apocalypticism, doomsdays, judgement days, prophets, messiahs, cyclical worldviews, and so on.
Extinction is generally a Type 0 and Type I concern; however higher types may be almost fully eradicated by enemies.
As a Type II civilization expands aggressively using FTL and sprawls far beyond its government, it may regress into societal collapse and eventually a form of interstellar barbarism with little regard for life. Eventually each faction may adopt its own government and culture and evolve into a new species, leaving its origins long forgotten and effectively extinct.
Type III and beyond will have found instantaneous travel and spacetime manipulation, and so the problems of sprawl and uncontrolled government may be a thing of the past. They could become sophonts, be part of benevolent and civilized galactic or universal associations, and eventually ascend into higher level beings, effectively making their original species with its flawed genetic code extinct.
Man-made (anthropogenic) ELEs:
| ELE | Description | Examples |
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| Artificial Intelligence | If AI systems rapidly become superintelligent, they may take unforeseen actions or out-compete humanity. This is the likely outcome of a Technological Singularity. There could also be an existential risk from artificial general intelligence. |
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| Biotechnology | Biotechnology can pose a global catastrophic risk in the form of bioengineered organisms (viruses, bacteria, fungi, plants or animals) or modified microbes such as a weaponized Ebola. In many cases the organism will be a pathogen of humans, livestock, crops or other organisms we depend upon. |
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| Cyberattack | Cyberattacks have the potential to destroy everything from personal data to electric grids. A cybergeddon is a cataclysmic economic collapse resulting from a large-scale sabotage of all computerized networks, systems and activities combining cyberterrorism, cyberwarfare, cybercrime, and hacktivism. | |
| Doomsday Machine | A weapon of immense power capable of destroying a civilization or an entire planet. |
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| Environmental disaster | An environmental or ecological disaster, such as world crop failure and collapse of ecosystem services, could be induced by the present trends of overpopulation, economic development, and non-sustainable agriculture. |
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| Holocene extinction (the sixth mass extinction or Anthropocene extinction) | An ongoing extinction event of species during the present Holocene epoch as a result of human activity. This spans families of bacteria, fungi, plants, mammals, birds, reptiles, amphibians, fish, and invertebrates. In 2021 the WWF suggested that over a million species could go extinct within a decade in the "largest mass extinction event since the end of the dinosaur age." |
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| Malthusian catastrophe | This event occurs when population growth outpaces agricultural production, causing famine or war, resulting in poverty and depopulation. Such a catastrophe sometimes allows a correction back to a lower, more easily sustainable level. |
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| Experimental technology accident | In the pursuit of knowledge, humanity might inadvertently create a device that could destroy Earth or even the Solar System. |
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| Global warming | Global warming, sea level rise, and an increase in the frequency and severity of some extreme weather events and weather-related disasters. Effects of global warming include loss of biodiversity, stresses to existing food-producing systems, increased spread of known infectious diseases such as malaria, and rapid mutation of microorganisms. | |
| Mineral resource exhaustion | Earth's capacity to sustain human populations and consumption levels is bound to decrease sometime in the future as Earth's finite stock of mineral resources is presently being extracted and put to use; and consequently, that the world economy as a whole will head towards an inevitable future collapse, leading to the demise of human civilization itself. |
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| Nanotechnology | Molecular manufacturing, used to build complex structures at atomic precision, can lead to self-replicating robots that consume the entire biosphere or beyond, using it as a source of energy and building blocks. This could lead to a technological singularity. | |
| Warfare and mass destruction | The futility of nuclear war and a nuclear winter. |
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| World population and agricultural crisis | Since supplies of petroleum and natural gas are essential to agriculture techniques, a fall in global oil supplies could cause spiking food prices and unprecedented famine. |
Non-anthropogenic ELEs:
| ELE | Description | Examples |
|---|---|---|
| Asteroid impact | A specific size or velocity of a Near Earth Object could obliterate all life on Earth. The Chicxulub crater event that killed the dinosaurs was a 10-to-15-km asteroid that hit Earth with 100 teratonnes of TNT, creating intense infrared radiation and firestorms that caused a greenhouse effect. The impact would have created a dust cloud that blocked sunlight, leading to a nuclear winter for three years. This killed off plant life and eliminated dinosaur food chains. The mean time between major impacts is estimated to be at least 100 million years. |
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| Cosmic threats | Black hole, gamma-ray burst, solar flare, home star going red giant or supernova.
A near-Earth supernova can impact the biosphere and gamma rays emitted by the supernova cause a depletion of the ozone layer that protects the surface from ultraviolet (UV) radiation from the Sun. On average, a supernova explosion occurs within 32 light-years once every few hundred million years, resulting in a depletion of the ozone layer lasting several centuries. The mean time for the Sun to collide with another star in the solar neighborhood is approximately 30 trillion years, so that is an extremely low likelihood even if a galaxy merger happens.
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| Extraterrestrial invasion | The possibility that an alien civilization will be far more powerful than ours, and will regard us as a nuisance or threat. | |
| Geological | A megathrust earthquake is where one tectonic plate slips beneath another, exceeding 9.0 on the Richter scale. |
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| Pandemic | The present, unprecedented scale and speed of human movement make it more difficult than ever to contain an epidemic through local quarantines, and other sources of uncertainty and the evolving nature of the risk mean natural pandemics may pose a realistic threat to human civilization. |
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| Natural climate change | Throughout Earth's climate history it has fluctuated between greenhouse and icehouse.
Snowball Earth proposes that during icehouse, Earth's surface becomes frozen, resulting in global glaciation and an ice-covered ocean. An icehouse results in an ice age.
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| Volcanism | A geological event such as the eruption of a supervolcano (like Yellowstone). Magma would be flung more than 50 km into the atmosphere. An explosion would have a force thousands of times that of Mount St. Helens. The thousands of cubic km of ash that would shoot into the atmosphere would block out light from the sun, making global temperatures fall dramatically, leading to a volcanic or nuclear winter. Most of the world’s plant life would be killed by the ash and there would be massive food shortages. Animal life would also be killed by breathing the deadly ash. A verneshot (named after Jules Verne) is caused when a mantle plume comes in contact with a craton. Lava and gases build up and erupt onto the surface creating continental flood basalts. When the pressure reaches an unbearable limit in the subsurface, it will cause a massive explosion where gases, debris and projectiles would be thrown into the atmosphere causing cataclysmic climatic effects on the environment. |
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| Hypercane | A hypercane is an extreme hurricane or cyclone that forms if ocean temperatures reach around 50 °C. They have wind speeds of over 800 km/h, an lifespan of weeks, and waves of 20 m. A hypercane’s clouds would reach 30 km into the stratosphere and damage the earth’s ozone. | |
| Mega Tsunami | A mega tsunami is a series of waves that could occur after an sea-quake or asteroid impact. If 500 billion tons of rock are displaced, that would create 1×1015 J of energy, which translates to 600 m to 1000 m tall waves moving at over 1000km/h. This would surge hundreds of km past the shoreline, completely destroying coasts, islands and large areas inland. |
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Planetary management and respecting planetary boundaries have been proposed as approaches to preventing ecological catastrophes. Solutions of this scope may require megascale engineering. Space colonization and becoming a multiplanetary species (starting with Mars) is an alternative to improve the odds of surviving an extinction scenario.
"The dinosaurs became extinct because they didn’t have a space program. And if we become extinct because we don’t have a space program, it’ll serve us right." — Larry Niven.