Also see: Mass extinction
Humans, just like any species, are not immortal. We have ways of predicting and avoiding the extinction of species, including ourselves, and perhaps someday ways to expand into the galaxy so wide we could never be wiped out, or at least our descendants. This is list of several proposed ways we could go extinct.
- Metasability event: Chemical & physical laws change.
- Global warming: Period of intense warming. As with Global climate change of any kind, a decrease in crop production could lead to widespread pestilence and nuclear exchange. Changes in temperature could have vast effects on small things, and up from there. This problem would be obsolete once we colonize other planets large scale.
- Ice age: Period of intense cooling. As with Global climate change of any kind, a decrease in crop production could lead to widespread pestilence and nuclear exchange. Similar to above.
- Geomagnetic reversal: North and south poles switch and fluctuate shutting off radio waves and sending lethal UV radation to ground level.
- Stranglet: an entity of strange matter that consumes normal matter, Earth.
- Polar Axis shift: the Earth's axis tilts to the east or west, changing ocean currents and climate. As with Global climate change of any kind, a decrease in crop production could lead to widespread pestilence and nuclear exchange.
- Blackhole: an entity that sucks everything (including light) in its opening.
- Pandemic: a disease that kills many people and spreads fast (AIDS, SARS, Ebola, Influenza). (This scenario is highly unlikely due to the fact Viruses have never completely wiped out a species)
- Asteroid/Comet impact: when a large body from space collides with earth.
- Gamma ray burst: a gamma ray is fired from the Hypernova of a Supermassive star which could destroy part of the ozone layer and create foggy air on the habitable side.
- Nuclear or World War III: Bombs are dropped on major cities killing millions instantly, with the nuclear radiation, winter, & summer taking care of any survivor. Even limited nuclear exchange (such as Pakistan vs. India) could affect global climate. This could be a Major possibility, Currentley Austro-Indonesian Allience is at it's lowest it would take just one more thing for Indonesia to invade Australia because of it's high deposit of Uranium and other importent Minerals it could begin The Nuclear War other variations and Scenarios include American vs iran or russia or the bombing of the UN or the Nuclear Bombing of Tokyo or other majorly importent city.
- Supervolcanic eruption: a super volcano will blow up the surrounding land (ex.Yellowstone national park, Lake Tambora) the pyroclastic flows and "volcano rain" cover and destroy places in a 2000 or so mile radius and the climate change that follows devastates the planet.
- CME/Solar Storm: The Sun ejects a CME (Coronal Mass Ejection), and it would interfere with atmospheric conditions, global electricity grids, and radio waves. Due to the CME's place on the radiation spectrum, it overloads circuits, rendering large power grids unusable. Increased UV radiation creates more atmospheric turmoil.
- Supernova : If a nearby star went supernova (explodes), it would endanger life in the solar system.
- Alien Invasion: Maybe Intelligent aliens would come to earth to wipe out any living thing to obtain mineral rescources (as proposed in Independence Day) or enslave life or even try to take other earth for settlements or even killing us of for destroying the enviroment. H G Wells imagined Martians have been watching us and maybe they could kill millions. Whether the Aliens have good or bad intentions, if the aliens are CHON life, it is likely they could exchange pathogens with us.
- Evolution : Possible, as subspecies could evolve and branch off into new species. Unnatural evolution and Directed evolution could also affect evolution.
Here are some that aren't as common or well explained
- New predation: a new better predator comes out of the blue and hunts easy, frail humans. As seen in the case of the Lions of Tanzania, any predation on humans would become futile.
- Grey goo: nanobots eat through all organic matter on Earth.
- Sudden loss or decrease of the sun's output: (ex. our rotation grows eliptical).
- Voluntary human extinction,
- Plasma discharge from the sun,
- Genetic relapse and/or collapse - 99% of all species that have gone extinct died from genetic collapse or relapse, due to a natural cycle.