Risks to Civilization, Humans and Planet Earth
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Risks to civilization, humans and planet Earth From Wikipedia, the free encyclopedia This is about the future of civilization, humans, and the earth. For past civilizations, see societal collapse. Contents Risks to civilization, humans, and planet ■ 1 Types of risks Earth are existential risks that could ■ 2 Future scenarios threaten humankind as a whole, have ■ 2.1 Cosmology and space adverse consequences for the course of ■ 2.1.1 Meteorite impact human civilization, or even cause the end of ■ 2.1.2 Other cosmic threats [1] planet Earth. The concept is expressed in ■ 2.2 Earth various phrases such as "End of the World", ■ 2.2.1 Global pandemic "Doomsday", "Armageddon", the Apocalypse ■ 2.2.2 Megatsunami and others. ■ 2.2.3 Climate Change & Global Warming ■ 2.2.3.1 Ice age Types of risks ■ 2.2.4 Ecological disaster ■ 2.2.5 World population and agricultural crisis Various risks exist for humanity, but not all ■ 2.2.6 Supervolcano are equal. Risks can be roughly categorized ■ 2.3 Humanity into six types based on the scope (personal, ■ 2.4 Other scenarios regional, global) and the intensity (endurable or terminal). The following chart provides ■ 3 Historical futurist scenarios some examples: ■ 4 See also ■ 5 Notes ■ 6 References Typology of risk [1] ■ 7 Further reading Endurable Terminal ■ 8 External links Plate Nearby Gamma Global tectonics ray burst Flash Permanent Regional flooding submersion Personal Assault Death The risks discussed in this article are at least Global and Terminal in intensity. These types of risks are ones where an adverse outcome would either annihilate intelligent life, or permanently and drastically reduce its potential. Jamais Cascio made an alternative classification system (http://www.openthefuture.com/2006/12/an_eschatological_taxonomy.html) . Future scenarios Many scenarios have been suggested. Some that will almost certainly end humanity are certain to occur, but 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: [2] Some foreseen hazards (hence not members of the current category) which have been excluded from the list on grounds that they seem too unlikely to cause a global terminal disaster are: solar flares, supernovae, black hole explosions or mergers, gamma-ray bursts, galactic center outbursts, buildup of air pollution, gradual loss of human fertility, and various religious doomsday scenarios. Cosmology and space On a very long time and distance scale, the ultimate fate of the universe is generally felt by scientists to be one that precludes the indefinite continuation of life. There are a broad spectrum of these predictive theories that fall in the realm of cosmology, but a long-established and widely-accepted notion is the Heat death of the universe. Most notions involve time periods much greater than the age of the universe, around 13 billion years. At the latest, in about 5 billion years, stellar evolution predicts our sun will exhaust its core hydrogen and become a red giant.[3][4][5] In doing so, it will become thousands of times more luminous. [6] As a red giant, the Sun will lose roughly 30% of its mass, so, without tidal effects, the Earth will be in an orbit 1.7 AU (250,000,000 km) from the Sun when the star reaches its maximum radius. Therefore, the planet is thought to escape envelopment by the expanded Sun's sparse outer atmosphere, though most (if not all) existing life would have been destroyed by the Sun's proximity to Earth. [3] However, a more recent simulation indicates that Earth's orbit will decay due to tidal effects and drag, causing it to enter the red giant Sun's atmosphere and be destroyed. [4][7][8] The Earth will likely be dragged into the Sun when it becomes an enlarged red giant by no later than about 7.6 billion years [9]; before actual collision with the sun, the oceans would evaporate, and Earth could be destroyed by tidal forces. Alternatively, if the Sun shrinks to a white dwarf before consuming Earth, the Earth would be too frigid to sustain life. Meteorite impact In the timeframe of the geologically recent history of the Earth, say, 100 million years, several large meteorites have hit Earth. The Cretaceous-Tertiary asteroid, for example, is theorized to have caused the extinction of the dinosaurs. If such an object struck Earth it could have a serious impact on civilization. It is even possible that humanity would be completely destroyed; for this, the asteroid would need to be at least 1 km (0.6 miles) in diameter, but probably between 3–10 km (2–6 miles).[10] Asteroids with a 1 km diameter impact the Earth every 500,000 years [10] on average. Larger asteroids are less common. The last large (>10 km) impact happened 65 million years ago. So-called Near-Earth asteroids are regularly being observed. A star passage that will 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. [11] Other models, such as the one by García-Sánchez, predict an increase of only 5%. Other cosmic threats A number of other scenarios have been suggested. Massive objects, e.g., a star, large planet or black hole, could be catastrophic if a close encounter occurred in the solar system. (Gravity from the wandering objects might disrupt orbits and/or fling bodies into other objects, thus resulting in meteorite impacts or climate change. Also, heat from the wandering objects might cause extinctions; tidal forces could cause erosion along our coastlines.) Another threat might come from gamma ray bursts.[12] Both are very unlikely. [2] Still others see extraterrestrial life as a possible threat to humankind; [13] although alien life has never been found, scientists such as Carl Sagan have postulated that the existence of extraterrestrial life is very likely. In 1969, the "Extra-Terrestrial Exposure Law" was added to the Code of Federal Regulations (Title 14, Section 1211) in response to the possibility of biological contamination resulting from the US Apollo Space Program. It was removed in 1991. [14] Scientists consider such a scenario technically possible, but unlikely. [15] In April 2008, it was announced that two simulations of long-term planetary movement, one at Paris Observatory and the other at University of California, Santa Cruz indicate a 1% chance that Mercury's orbit could be made unstable by Jupiter's gravitational pull sometime during the lifespan of the sun. Were this to happen, the simulations suggest a collision with Earth could be one of four possible outcomes (the others being colliding with the Sun, colliding with Venus, or being ejected from the solar system altogether). If this were to happen, all life on Earth would be obliterated and the impact may displace enough matter into orbit to form another moon. Note that an asteroid just 15 km wide is said to have destroyed the dinosaurs; Mercury is some 5,000 km in diameter. [16] Earth Global pandemic Main article: Pandemic A less predictable scenario is a global pandemic. For example, if HIV were to mutate and become as transmissible as the common cold, the consequences would be disastrous. [17] This particular scenario would also contradict the observable tendency for pathogens to become less fatal over time as a function of natural selection. A pathogen that quickly kills its hosts will not likely have enough time to spread to new ones, while one that kills its hosts more slowly or not at all will allow carriers more time to spread the infection, and thus likely outcompete a more lethal species or strain. A real-life example of this process can be found in the historical evolution of syphilis towards a less virulent form (http://www.qmul.ac.uk/news/newsrelease.php? news_id=9) . Also, as a virus mutates and becomes easily transmittable it often gives up much of its virulence in the process. This is not to say that a highly destructive and highly transmissible disease is not possible. Ebola, for example, is highly contagious and up to 90% fatal; the only reason it has not caused a worldwide crisis is because outbreaks usually occur in rural Africa. Of course, a pandemic resulting in human extinction need not arise naturally; the possibility of one caused by a deliberately-engineered pathogen cannot be ruled out. Megatsunami Main article: Megatsunami Another possibility is a 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 also be flooded in case of the collapse of the West Antarctic Ice Sheet.[18] While none of these scenarios are likely to destroy humanity completely, they could regionally threaten civilization. There has been one recent high-fatality tsunami, although it was not large enough to be considered a megatsunami. Climate Change & Global Warming Main article: Global warming Climate change is any long-term significant change in the expected patterns of average weather of a specific region (or, more relevantly to contemporary socio-political concerns, of the Earth as a whole) over an appropriately significant period of time. Climate change reflects abnormal variations to the expected climate within the Earth's atmosphere and subsequent effects on other parts of the Earth, such as in the ice caps over durations ranging from decades to millions of years.