End of civilization: Encyclopedia II - End of civilization - Future scenarios

End of civilization - Future scenarios

There are many scenarios that have been suggested that could happen in the future. Some are certain to happen and will almost certainly end humanity, but will only happen on a very long timescale. Others are likely to happen on a shorter timescale, but will probably not completely destroy civilization. Still others are extremely unlikely, and may even be impossible. For example, Nick Bostrom writes ^[3]:

See also: Human extinction scenarios.

End of civilization - Space

It is certain that events in space will cause life on Earth to come to an end. The certain events, however, will happen at an extremely long timescale measured in billions of years. Projections indicate that the Andromeda Galaxy is on a collision course with the Milky Way. Impact is predicted in about 3 billion years, and so Andromeda will approach at an average speed of about 140 kilometres per second; the two galaxies will probably merge to form a giant elliptical. This merging will most likely either eject our solar system into deep space or bombard it with other solar systems, either way causing our planet to become uninhabitable (an actual collision is unnecessary). In 5 to 6 billion years, stellar evolution predicts our sun will evolve in a red giant ^[4] and will probably completely envelop the earth. This will occur as long as the sun's gravity, which will reduce over time as it radiates its mass away, is still able to keep Earth in a close enough orbit. Even if the Earth does move out to a more distant orbit, there may not be enough energy to sustain life since the effective temperature of a red giant decreases (radiates less heat) as it grows in size. Besides the red giant option, there are some astronomers who believe that the sun is currently increasing in luminosty (at a very slow rate), and they predict that in fewer than one billion years, the Earth will be too hot for life as we know it to survive, and have too much radiation as well.

On an even longer time scale, the universe will come to an end. There are competing scientific models on how this will happen exactly, but in all cases, there will be no life possible. The current age of the universe is estimated as being 13.7 billion years. There are several competing theories as to the nature of our universe and how it will end. This takes place on an even longer timescale than the expanding of the sun.

In the history of the Earth, it is widely accepted that several large meteorites have hit Earth. One is theorized to have caused the extinction of the dinosaurs. If a large meteorite hit Earth it could have a serious impact on civilization. It's even possible that humanity would be completely destroyed: for this, the asteroid would need to be at least 1 km in diameter, but probably between 3–10 km ^[5]. Asteroids with 1 km in diameter probably happen every 0.5 million years ^[6]. Larger asteroids are more rare. The last large impact happened 65 million years ago. So-called Near-Earth asteroids are regularly being observed.

Some scientists believe there are patterns in the amount of meteorites hitting the earth. A possible explanation of such a pattern is given by the hypothetical Nemesis star. There is a theory stating that this regularly passes through a denser part of the Oort cloud, causing meteorite rains to collide onto earth. However, the very existence of this pattern is not widely accepted, and the existence of the Nemesis star is highly controversial.

Another scenario that might cause an increase of meteorites is the arrival of a star called Gliese 710. This star is probably moving on a collision course with the Solar System and will likely be at a distance 1.1 light years from the Sun in 1.4 million years. Some models predict that this will send large amounts of comets from the Oort cloud to the Earth[7]. Other models, such as the one by García-Sánchez, predict an increase of only 5%.

A number of other scenarios have been suggested. A Black Hole could enter the solar system ^[8]. If this happened, the result would be catastrophic. Another threat might come from Gamma ray bursts; some scientists believe this may have caused mass extinction 450 million years ago ^[9]. Both are very unlikely ^[10]. Still others see Extraterrestrial life as a possible threat to mankind ^[11]; although alien life has never been found, scientists such as Carl Sagan have postulated that the existence of extraterrestrial life is very likely. Even NASA at one time sterilized items returning from space to kill any potential "alien" bugs that might threaten humanity. Scientists consider such a scenario possible, but unlikely^[12].

End of civilization - Earth

In the history of the Earth, many ice ages have happened. More ice ages will almost certainly come at an interval of 40,000–100,000 years. This would have a serious impact on civilization as we know it today, because vast areas of land (mainly in North-America and Europe) would become uninhabitable. It would still be possible to live in the tropical regions.

A less predictable scenario is a global pandemic. For example, if HIV mutates and becomes as transmissible as the common cold, the consequences would be fatal, but probably not fatal to the human species,^[13] as some people are immune to HIV.

A scenario that is less predictable is the megatsunami. A megatsunami could, for example, destroy the entire east coast of the United States of America. The coastal areas of the entire world could be flooded in case of the collapse of the West Antarctic Ice Sheet ^[14]. While none of these scenarios could possibly destroy humanity completely, they could regionally threaten civilization as we know it.

When the supervolcano at Yellowstone last erupted, 74,000 years ago, the magma covered roughly all of the area of North America west of the Mississippi river. Another such erruption could threaten civilization. Such an eruption could also release large amounts of gases that could alter the balance of the planet's carbon dioxide and cause a runaway greenhouse effect, or enough pyroclastic debris and other material may be thrown into the atmosphere to partially block out the sun and cause a natural "Nuclear winter"

End of civilization - Humanity

Probably the biggest threat for humanity comes from humanity itself ^[15]. The scenario that has been explored most is a nuclear war or another weapon with similar possibilities. It is difficult to predict whether it would exterminate humanity, but very certainly could alter civilization as we know it, in particular if there was a nuclear winter event ^[16].

Another category of disasters are unforeseen consequences of technology. It has been suggested that learning computers take unforeseen actions or that robots would out-compete humanity ^[17]. Biotechnology could lead to the creation of a pandemic, Nanotechnology could lead to grey goo - in both cases, either deliberately or by accident. ^[18] It has also been suggested that physical scientists might accidentally create a device that could destroy the earth and the solar system ^[19]. In string theory, there are some unknown variables. If those turn out to have an unfortunate value, the universe may not be stable and alter completely, destroying everything in it ^[20], either at random or by an accidental experiment. This is called Quantum Vacuum Collapse by some^[21]. Another kind of accident is the Ice-9 Type Transition, in which our planet including everything on it becomes a strange matter planet in a chain reaction. Some do not view this as a credible scenario^[22].

It has been suggested that runaway global warming might cause the climate on Earth to become like Venus, which would make it uninhabitable. In less extreme scenarios it could cause the end of civilization as we know it. ^[23]

Other scenarios that have been named are:

• Antibiotic resistance. Natural selection would create super bacteria that are resistant to antibiotics, devastating the world population and causing a global collapse of civilization.
• Catastrophe theory predicts a software-complexity tipping point when the integrated world becomes vulnerable to disastrous bugs in the system.
• Demography. Demographic trends create a "baby bust" that threatens the order of civilization as we know it.^[24]
• Dysgenics. A lack of natural selection and the tendency of the more intelligent to have fewer children would lower the average health and intelligence enough to lead to an eventual collapse of civilization.
• Ecology. Natural resources are used up, or the environment is so damaged through pollution and destruction that civilization fails.
• Finance. Markets fail worldwide, resulting in economic collapse: mass unemployment, rioting, famine, and death.
• Infertility. Human fertility continues to decline, eventually ending with no fertile humans left to continue the species.
• Insanity. Mass insanity.
• Peak oil. Oil runs out before an economically viable replacement is devised, leading to global chaos.^[25]
• Telomere. Some researchers theorize a tiny loss of telomere length from one generation to the next, mirroring the process of aging in individuals. Over thousands of generations the telomere erodes down to its critical level. Once at the critical level we would expect to see outbreaks of age-related diseases occurring earlier in life and finally a population crash.^[26]
• World government. Misguided world government caps progress, leading to stagnation and reversals of Civilization.

End of civilization - Religion

End of civilization - Fictional

Adapted from the Wikipedia article "Future scenarios", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki