The Holocene Human Extinction

Human extinction

Human extinction is the end of the human species. Various scenarios have been discussed in science, popular culture and religion (see End time). The scope of this article is existential risks. Humans are very widespread on the Earth, and live in communities which (whilst interconnected) are capable of some kind of basic survival in isolation. Therefore, pandemic and deliberate killing aside, to achieve human extinction, the entire planet would have to be rendered uninhabitable, with no opportunity provided or possible for humans to establish a foothold beyond Earth. This would typically be during a mass extinction event, a precedent of which exists in the Permian–Triassic extinction event among other examples.

In the near future, anthropogenic extinction scenarios exist: global nuclear annihilation, overpopulation[1] or global accidental pandemic; besides natural ones: bolide impact and large scale volcanism or other catastrophic climate change. These natural causes have occurred multiple times in the geologic past although the probability of reoccurrence within the human timescale of the near future is infinitesimally small. As technology develops, there is a theoretical possibility that humans may be deliberately destroyed by the actions of a nation state, corporation or individual in a form of global suicide attack. There is also a theoretical possibility that technological advancement may resolve or prevent potential extinction scenarios. The emergence of a pandemic of such virulence and infectiousness that very few humans survive the disease is a credible scenario. While not actually a human extinction event, this may leave only very small, very scattered human populations that would then evolve in isolation. It is important to differentiate between human extinction and the extinction of all life on Earth. Of possible extinction events, only a pandemic is selective enough to eliminate humanity while leaving the rest of complex life on earth relatively unscathed.

Possible scenarios

See also: Risks to civilization, humans and planet Earth

It has been suggested that this article or section be merged with Risks to civilization, humans and planet Earth. (Discuss) Proposed since July 2010.

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2010)

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Severe forms of known or recorded disasters

• Warfare, whether nuclear or biological or conventional (although nuclear weapons and biological agents are likely to be used); see World War III.
• Pandemic involving an antibiotic-resistant bacterium, antifungal-resistant fungus, prion, or antiviral-resistant virus. Past examples include the Spanish flu outbreak in 1918 and the 2009 flu pandemic.

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Environmental collapses

• Loss of a breathable atmosphere, for example due to an anoxic event.
• Occurrence of a large-scale volcanism, possibly a supervolcano (250 million years ago, after the Permian–Triassic extinction event life on land took 30 million years to recover).[2]
• Extreme ice age leading to prolonged global drought. An ice age can be a result of a nuclear winter or natural forces.
• Loss of natural resources, such as mass deforestation or contamination of all fresh water.

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Tipping points in climate systems

Tim Lenton has been studying what he calls tipping points in climate systems.[3] He has described nine such possibilities of sudden climate change:

• The Indian summer monsoon, which is needed to sustain crops, could collapse anytime as land-to-ocean pressure gradients change with pollution and warming patterns. That could lead to an "erratic" fluctuation that would "chaotically change between an active and a weak phase." This is considered an "intermediately sensitive" tipping point with large uncertainty.
• The Sahara and Sahel in Africa could change dramatically, becoming either far more dry or far more wet, as ocean temperature and vegetation-climate feedbacks change within a decade or so. This is considered an "intermediately sensitive" tipping point with large uncertainty.
• Arctic sea ice, which reached its lowest known extent in the summer of 2007, could disappear completely in summer within a decade or so, as the open water absorbs more heat from the sun than is reflected by white ice. This is considered a "highly sensitive" tipping point with low uncertainty.
• The Greenland ice sheet could decay within 300 years as cycles of degradation and regrowth tip toward melting within 300 years or more. This could lead to a rise in sea levels of more than 20 feet. This is considered a "highly sensitive" tipping point with low uncertainty.
• The Atlantic thermohaline circulation, which ensures the Gulf Stream warmth reaches Europe, could collapse within 100 years as warming of the oceans alters water density and disrupts the global circulation of the seas. This is considered a "lowly sensitive" tipping point, with intermediate uncertainty.
• The West Antarctic ice sheet could collapse within 300 years, leading to a sea level rise of as much as 15 feet worldwide. This is considered an "intermediately sensitive" tipping point with large uncertainty.
• The Amazon rainforest could dieback significantly within 50 years due to a combination of deforestation and global warming, which could trigger a 30% decrease in rainfall. This is considered an "intermediately sensitive" tipping point with large uncertainty.
• The Boreal Forest, which rings the northern latitudes and provides habitat for migratory bird species and other wildlife, could die back within 50 years as trees succumb to summer heat stress, increased diseases and other threats. This is considered an "intermediately sensitive" tipping point with large uncertainty.
• The El Niño Southern Oscillation, which refers to patterns of warming and cooling in the Pacific Ocean that affect weather worldwide, could within 100 years change to a persistent warm or cool pattern, or change so that warm El Nino patterns are more intense, leading to more intense droughts in some area, and likelihood of flooding elsewhere. This is considered an "intermediately sensitive" tipping point with large uncertainty.

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Long-term habitat threats

• Within a million years, the hypergiant Eta Carinae, which is 7500 light years from the Sun, may go hypernova. It is unlikely, however, to affect terrestrial lifeforms directly, as they will be protected from gamma rays by the atmosphere, and from some other cosmic rays by the magnetosphere.
• In 1.4 million years Gliese 710 will be only 1.1 light years from Earth and might catastrophically perturb the Oort cloud, possibly resulting in a comet shower.
• In about 1 billion years, the Earth's oceans will disappear, due to the Sun brightening. However, well before this, the level of carbon dioxide in the atmosphere will be too low to support plant life, destroying the foundation of the food chains.[4]
• In about 3 billion years, our Milky Way galaxy is expected to collide with the Andromeda galaxy. Collisions of individual bodies will likely be scarce; however, the consequences for orbits of stars and planets are unclear, and impossible to predict for individual stellar systems.
• In 5 billion years hence the Sun's stellar evolution will reach the red giant stage, in which it will expand and possibly engulf Earth. But before this happens it will already have changed Earth's climate and its radiated spectrum may alter in ways Earth-bound humans could not survive.[5]

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Evolution

• Evolution resulting in declining human intelligence. (See Idiocracy.)
• Evolution of another species that out-competes humans for food, habitat or hunts as prey.

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Overpopulation

Overpopulation leads to higher risk of famine due to the increasing need for centralized agriculture with a lack of biodiversity. A single staple crop getting a disease or pest attack could lead to mass food crisis. The transition from fossil fuel chemical based agriculture to future alternatives such as organic agriculture will be a more risky transition with a high population. The world currently uses around 40% of its land mass for agriculture and almost all of its arable land.[6] Overpopulation also puts a strain on the environment and natural resources that are in many ways relied upon for survival.

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Population decline

Further information: Population decline

• Preference for fewer children; if developed world demographics are extrapolated they mathematically lead to 'soft' extinction before 3000 CE. (John A. Leslie estimates that if the reproduction rate drops to the German level the extinction date will be 2400.[1])
• Political intervention in reproduction has failed to raise the birth rate above the replacement level in the rich world, but has dramatically succeeded in lowering it below the replacement level in China.^[citation needed^] (See One child policy.) A World government with a eugenic or small population policy could send humanity into 'voluntary' extinction.
• Infertility: Caused by hormonal disruption from the chemical/pharmaceutical industries, or biological changes, such as the (controversial) findings of falling sperm cell count in human males. (See The Children of Men (novel) or Children of Men (film).)
• A disruption, chemical, biological, or otherwise, in humans' ability to reproduce properly or at all.
• Voluntary extinction, activists may strive for this form of extinction.
• The ability of cloning however would be able to prevent population decline provided humans were able and willing to use the technology.

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Scientific accidents

• In his book Our Final Hour, Sir Martin Rees claims that without the appropriate regulation, scientific advancement increases the risk of human extinction as a result of the effects or use of new technology. Some examples are provided below.
• Uncontrolled nanotechnology (grey goo) incidents resulting in the destruction of the Earth's ecosystem (ecophagy).
• Creation of a "micro black hole" on Earth during the course of a scientific experiment, or other foreseeable scientific accidents in high-energy physics research, such as vacuum phase transition or strangelet incidents. There were worries concerning the Large Hadron Collider at CERN as it is feared that collision of protons at a speed near the speed of light will result in the creation of a black hole, but it has been pointed out that much more energetic collisions take place currently in Earth's atmosphere.
• Significant destruction of crops by pesticide-resistant pests—which evolved in response to overuse of pesticide and genetically modified "super" plants^[citation needed^]—or lack of pollination from uncurbed honeybee colony collapse disorder.

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Scenarios of extraterrestrial origin

• Major impact events.
• If a rogue black hole passed near the Sun, it could disrupt Earth's orbit. (See "A Pail of Air".)
• Gamma-ray burst in our part of the Milky Way. (Bursts observable in other galaxies are calculated to act as a "sterilizer", and have been used by some astronomers to explain the Fermi paradox.) The lack of fossil record interruptions, and relative distance of the nearest Hypernova candidate make this a long term (rather than imminent) threat.
• Wolf-Rayet star WR 104, which is 8000 light years from the Sun, may produce a gamma ray burst aimed at the Sun when it goes supernova.
• Invasion by militarily superior extraterrestrials (see alien invasion) — often considered to be a scenario purely from the realms of science fiction, professional SETI researchers have given serious consideration to this possibility, but conclude that it is unlikely.[2]
• Gerard O'Neill has cautioned that first contact with alien intelligence may follow the precedent set by historical examples of contact between human civilizations, where the less technologically-advanced civilization has inevitably succumbed to the other civilization, regardless of its intentions.
• Solar flares may suddenly heat the earth, or the light from the sun may be blocked by dust, slowly freezing it (e.g. the dust and vapour may come from a Kuiper belt disturbance).
• A vacuum phase transition could destroy the universe.
• Biological contamination upon contact with extraterrestrial life.

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Philosophical scenarios

Future cultural evolution may result in suppression of self-preservation animal instinct, making possible a conscious collective choice for extinction.

Further information: Religion

Further information: Eschatology

Further information: Jonestown

Attitudes to human extinction

Attitudes to human extinction vary widely depending on beliefs concerning spiritual survival (souls, heaven, reincarnation, and so forth), the value of the human species, whether the human species evolves individually or collectively, and many other factors. Many religions prophesy an "end times" to the universe. Human extinction is therefore a part of the faith of many humans to the extent that the end time means the absolute end of their physical humanity but perhaps not an eternal soul.

However not all faiths connect human extinction to the end times, since some believe in cyclical regeneration, or that end times actually means the beginning of a new kind of existence (see eschatology and utopianism).

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Perception of human extinction risk

The general level of fear about human extinction, in the near term, is very low, despite the pronouncements of some fringe groups. It is not an outcome considered by many as a credible risk. Suggested reasons for human extinction's low public visibility:

1. There have been countless prophecies of extinction throughout history; in all cases the predicted date of doom has passed without much notice, such as 2012, making future warnings less frightening. However, a survivor bias would undercut the credibility of accurate extinction warnings. John von Neumann was probably wrong in having “a certainty”[3] that nuclear war would occur; but our survival is not proof that the chance of a fatal nuclear exchange was low (or indeed that such an event could not occur in the future).
2. Extinction scenarios (see below) are speculative, and hard to quantify. A frequentist approach to probability cannot be used to assess the danger of an event that has never been observed by humans.
3. Nick Bostrom, head of the James Martin 21st Century School Future of Humanity Institute, has suggested that extinction risk-analysis may be an overlooked field because it is both too psychologically troublesome a subject area to be attractive to potential researchers and because the lack of previous human species extinction events leads a depressed view of the likelihood of it happening under changing future circumstances (an 'inverse survivorship bias').
4. There are thousands of public safety jobs dedicated to analyzing and reducing the risks of individual death. There are no full-time existential safety commissioners partly because there is no way to tell if they are doing a good job, and no way to punish them for failure. The inability to judge performance might also explain the comparative governmental apathy on preventing human extinction (as compared to panda extinction, say).
5. Some anthropologists believe that risk perception is biased by social structure; in the "Cultural Theory of risk" typography "individualist" societies predispose members to the belief that nature operates as a self-correcting system, which will return to its stable state after a disturbance. People in such cultures feel comfortable with a "trial-and-error" approach to risk, even to unsuitably rare dangers (such as extinction events).
6. It is possible to do something about dietary or motor-vehicle health threats. Since it is much harder to know how existential threats should be minimized[4], they tend to be ignored. High technology societies tend to become "hierarchist" or "fatalist" in their attitudes to the ever-multiplying risks threatening them. In either case, the average member of society adopts a passive attitude to risk minimization, culturally, and psychologically.
7. The bias in popular culture is to relate extinction scenario stories with non-extinction outcomes. (None of the 16 'most notable' WW3 scenarios in film are resolved by human extinction, for example.[5])
8. The threat of nuclear annihilation actually was a daily concern in the lives of many people from the 1950s through the 1980s. Since then the principal fear has been of localized terrorist attack, rather than a global war of extinction.
9. Some people have philosophical reasons for doubting the possibility of human extinction, for instance the final anthropic principle, plenitude principle or intrinsic finality.
10. Tversky and Kahneman have produced evidence that humans suffer cognitive biases which would tend to minimize the perception of this unprecedented event:
1. Denial is a negative "availability heuristic" shown to occur when an outcome is so upsetting that the very act of thinking about it leads to an increased refusal to believe it might occur. In this case, imagining human extinction probably makes it seem less likely.
2. In cultures where human extinction is not expected the proposition must overcome the "disconfirmation bias" against heterodox theories.
3. Another reliable psychological effect relevant here is the "positive outcome bias".
4. Behavioural finance has strong evidence that recent evidence is given undue significance in risk analysis. Roughly speaking, "100 year storms" tend to occur every twenty years in the stock market as traders become convinced that the current good times will last forever. Doomsayers who hypothesize rare crisis-scenarios are dismissed even when they have statistical evidence behind them. An extreme form of this bias can diminish the subjective probability of the unprecedented.[6]

In general, humanity's sense of self preservation, and intelligence are considered to offer safe-guards against extinction. It is felt that people will find creative ways to overcome potential threats, and will take care of the precautionary principle in attempting dangerous innovations. The arguments against this are; firstly, that the management of destructive technology is becoming difficult, and secondly, that the precautionary principle is often abandoned whenever the reward appears to outweigh the risk. At least one instance where the principle may have been overruled was when prior to the Trinity nuclear test, one of the project's scientists (Teller) speculated that the fission explosion might destroy New Mexico and possibly the world, by causing a reaction in the nitrogen of the atmosphere. A calculation by Hans Bethe proved such a possibility theoretically impossible, but the fear of the possibility remained among some until the test took place.

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Observations about human extinction

The fact that the vast majority of the species that have existed on Earth have become extinct, has led to the suggestion that all species have a finite lifespan and thus human extinction would be inevitable. Dave Raup and Jack Sepkoski found for example a twenty-six-million-year periodicity in elevated extinction rates, caused by factors unknown (See David M. Raup. "Extinction: Bad Genes or Bad Luck" (1992, Norton). Based upon evidence of past extinction rates Raup and others have suggested that the average longevity of an invertebrate species is between 4-6 million years, while that of vertebrates seems to be 2-4 million years. The shorter period of survival for mammals lies in their position further up the food chain than many invertebrates, and therefore an increased liability to suffer the effects of environmental change. A counter-argument to this is that humans are unique in their adaptive and technological capabilities, so it is not possible to draw reliable inferences about the probability of human extinction based on the past extinctions of other species. Certainly, the evidence collected by Raup and others suggested that generalist, geographically dispersed species, like humans, generally have a lower rate of extinction than those species that require a particular habitat. In addition, the human species is probably the only species with a conscious prior knowledge of their own demise, and therefore would be likely to take steps to avoid it.

Humans are very similar to other primates in their propensity towards intra-species violence; Jared Diamond's The Third Chimpanzee (ISBN 0-09-980180-9) estimates that 64% of hunter-gather societies engage in warfare every two years. Although it has been argued (e.g. in the UNESCO Seville Statement) that warfare is a cultural artifact, many anthropologists^[citation needed^] dispute this, noting that small human tribes exhibit similar patterns of violence to chimpanzee groups, the most murderous of the primates, and one of two of our nearest living genetic relatives. The "higher" functions of reason and speech are more developed in the brain of Homo sapiens than other primates, but the relative size of the limbic system is a constant in apes, monkeys and humans. The combination of inventiveness and urge to violence in humans has been cited as evidence against its long term survival.[7]

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Omnicide

Part of a series on

Homicide

Murder

Note: Varies by jurisdiction ▪ Assassination Child murder Consensual homicide Contract killing Crime of passion Depraved-heart murder Double murder Execution-style killing Felony murder rule Feticide Honor killing Human sacrifice Child Lust murder Lynching Mass murder Misdemeanor murder Murder–suicide Proxy murder Pseudocommando Lonely hearts killer Serial killer Spree killer Torture murder Internet homicide

Manslaughter

in English law Negligent homicide Vehicular homicide

Non-criminal homicide

Note: Varies by jurisdiction Euthanasia (Assisted suicide) Capital punishment Feticide Human sacrifice Justifiable homicide War

By victim or victims

Suicide

Family

▪ ▪ Familicide Avunculicide Prolicide Filicide Infanticide Neonaticide Fratricide Mariticide Sororicide Uxoricide Parricide Matricide Patricide

Other

Democide Friendly fire Genocide Gendercide Omnicide Regicide Tyrannicide

v t e

Omnicide is human extinction as a result of human action. Most commonly it refers to extinction through nuclear warfare or biological warfare,[7][8][9] but it can also apply to extinction through means such as global anthropogenic ecological catastrophe.[10]

Omnicide can be considered a subcategory of genocide.[11] Using the concept in this way, one can argue, for example, that:

“

The arms race is genocidal in intent given the fact that the United States and the Soviet Union are knowingly preparing to destroy each other as viable national and political groups.[12]

”

As this claim illustrates, the concept of omnicide raises issues of human agency and, hence, of moral responsibility in discussions about large-scale social processes like the nuclear arms race or ecologically destructive industrial production. That is, part of the point of describing a human extinction scenario as 'omnicidal' is to note that, if it were to happen, it would result not just from natural, uncontrollable evolutionary forces, or from some random catastrophe like an asteroid impact, but from deliberate choices made by human beings. This implies that such scenarios are preventable, and that the people whose choices make them more likely to happen should be held morally accountable for such choices. In this context, the label 'omnicide' also works to de-normalize the course of action it is applied to.

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In popular culture

The book The World Without Us by Alan Weisman deals with a thought experiment on what would happen to the planet and especially human-made infrastructures if humans suddenly disappeared. The Discovery Channel documentary miniseries The Future Is Wild shows the possible future of evolution on Earth without humans. The History Channel's special Life After People examines the possible future of life on Earth without humans, and was made into a series of the same name. The National Geographic Channel's special Aftermath: Population Zero envisions what the world be like if all humans suddenly disappeared. The British science-fiction drama Primeval also puts forward an alternative view of Earth after the extinction of humans: how other species of animals, such as rodents and insects will evolve to fill niches left by humans. The video-game franchise, Pikmin depicts the main character, Captain Olimar, arriving on a planet hugely resembling Earth, yet no humans are seen. Pikmin 2 depicts Olimar and his new partner, Louie, returning to the Pikmin Planet to collect "treasures". These treasures are usually man-made items like bottle caps and batteries.

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See also

• 10 Ways to End the World
• 2012 phenomenon (Numerologically derived eschatology, with arbitrary extinction mechanism.)
• Death from the Skies
• Extinction
• Extinction event
• Holocene extinction event
• Mutual assured destruction
• Risks to civilization, humans and planet Earth
• Space and survival
• Toba catastrophe theory
• Voluntary Human Extinction Movement

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Notes

^ Von Neumann said it was "absolutely certain (1) that there would be a nuclear war; and (2) that everyone would die in it" (underline added to quote from: The Nature of the Physical Universe – 1979, John Wiley & Sons, ISBN 0-471-03190-9, in H. Putnam’s essay The place of facts in a world of values - page 113). This example illustrates why respectable scientists are very reluctant to go on record with extinction predictions: they can never be proven right. (The quotation is repeated by Leslie (1996) on page 26, on the subject of nuclear war annihilation, which he still considered a significant risk – in the mid 1990s.)

^ Although existential risks are less manageable by individuals than health risks, according to Ken Olum, Joshua Knobe, and Alexander Vilenkin the possibility of human extinction does have practical implications. For instance, if the “universal” Doomsday argument is accepted it changes the most likely source of disasters, and hence the most efficient means of preventing them. They write: "...you should be more concerned that a large number of asteroids have not yet been detected than about the particular orbit of each one. You should not worry especially about the chance that some specific nearby star will become a supernova, but more about the chance that supernovas are more deadly to nearby life then we believe." Source: “Practical application” page 39 of the Princeton University paper: Philosophical Implications of Inflationary Cosmology 

^ The 2000 review Armageddon at the Millennial Dawn  from The Journal of Religion and Film finds that "While end of the world threats perhaps are not avoidable, the cinematic formulation of millennial doom promotes the notion that the end can be averted through employing human ingenuity, scientific advance, and heroism." Since this review was conducted, there had been a Hollywood production which postulates a (far future) outcome where humans are extinct (at least in the wild): A.I..

^ For research on this, see Psychological science volume 15 (2004): Decisions From Experience and the Effect of Rare Events in Risky Choice . The under-perception of rare events mentioned above is actually the opposite of the phenomenon originally described by Kahneman in "prospect theory" (in their original experiments the likelihood of rare events is overestimated). However, further analysis of the bias has shown that both forms occur: When judging from description people tend to overestimate the described probability, so this effect taken alone would indicate that reading the extinction scenarios described here should make the reader overestimate the likelihood of any probabilities given. However, the effect that is more relevant to common consideration of human extinction is the bias that occurs with estimates from experience, and these are in the opposite direction: When judging from personal experience people who have never heard of or experienced their species become extinct would be expected to dramatically underestimate its likelihood. Sociobiologist E. O. Wilson argued that: "The reason for this myopic fog, evolutionary biologists contend, is that it was actually advantageous during all but the last few millennia of the two million years of existence of the genus Homo... A premium was placed on close attention to the near future and early reproduction, and little else. Disasters of a magnitude that occur only once every few centuries were forgotten or transmuted into myth." (Is Humanity Suicidal? New York Times Magazine May 30, 1993).

^ Abrupt.org 1996 editorial  lists (and condemns) the arguments for human’s tendency to self-destruction. In this view, the history of humanity suggests that humans will be the cause of their own extinction. However, others have reached the opposite conclusion with the same data on violence and hypothesize that as societies develop armies and weapons with greater destructive power, they tend to be used less often. It is claimed that this implies a more secure future, despite the development of WMD technology. As such this argument may constitute a form of deterrence theory. Counter-arguments against such views include the following: (1) All weapons ever designed have ultimately been used. States with strong military forces tend to engage in military aggression, (2) Although modern states have so far generally shown restraint in unleashing their most potent weapons, whatever rational control was guaranteed by government monopoly over such weapons becomes increasingly irrelevant in a world where individuals have access to the technology of mass destruction (as proposed in Our Final Hour, for example).

^ ReligiousTolerance.org says that Aum Supreme Truth is the only religion known to have planned Armageddon for non-believers . Their intention to unleash deadly viruses is covered in Our Final Hour, and by Aum watcher, Akihiko Misawa . The Gaia Liberation Front advocates (but is not known to have active plans for) total human genocide, see: GLF, A Modest Proposal . Leslie, 1996 says that Aum’s collection of nuclear physicists presented a doomsday threat from nuclear destruction as well, especially as the cult included a rocket scientist.

^ Leslie (1996) discusses the survivorship bias (which he calls an "observational selection" effect on page 139) he says that the a priori certainty of observing an "undisasterous past" could make it difficult to argue that we must be safe because nothing terrible has yet occurred. He quotes Holger Bech Nielsen’s formulation: “We do not even know if there should exist some extremely dangerous decay of say the proton which caused eradication of the earth, because if it happens we would no longer be there to observe it and if it does not happen there is nothing to observe.” (From: Random dynamics and relations between the number of fermion generations and the fine structure constants, Acta Pysica Polonica B, May 1989).

^ For example, in the essay Why the future doesn't need us, computer scientist Bill Joy argued that human beings are likely to guarantee their own extinction through transhumanism. See: Wired archive, Why the future doesn't need us .

^ For the “West Germany” extrapolation see: Leslie, 1996 (The End of the World) in the “War, Pollution, and disease” chapter (page 74). In this section the author also mentions the success (in lowering the birth rate) of programs such as the sterilization-for-rupees programs in India, and surveys other infertility or falling birth-rate extinciton scenarios. He says that the voluntary small family behaviour may be counter-evolutionary, but that the meme for small, rich families appears to be spreading rapidly throughout the world. In 2150 the world population is expected to start falling.

^ See estimate of contact’s probability at galactic-guide . Former NASA consultant David Brin's lengthy rebuttal to SETI enthusiast's optimism about alien intentions concludes: "The worst mistake of first contact, made throughout history by individuals on both sides of every new encounter, has been the unfortunate habit of making assumptions. It often proved fatal." (See full text at SETIleague.org .)

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References

1. ^ http://www.dailymail.co.uk/sciencetech/article-1287643/Human-race-extinct-100-years-population-explosion.html 
2. ^ Sahney, S. and Benton, M. J. (2008). "Recovery from the most profound mass extinction of all time"  (PDF). Proceedings of the Royal Society: Biological 275 (1636): 759–65. doi:10.1098/rspb.2007.1370 . PMC 2596898 . PMID 18198148 .
3. ^ Lenton, T. M.; Held, H.; Kriegler, E.; Hall, J. W.; Lucht, W.; Rahmstorf, S.; Schellnhuber, H. J. (2008). "Tipping Elements in the Earth's Climate System". PNAS 105 (6): 1786–1793. doi:10.1073/pnas.0705414105 . edit
4. ^ http://news.bbc.co.uk/2/hi/sci/tech/specials/washington_2000/649913.stm 
5. ^ space.com 
6. ^ http://news.nationalgeographic.com/news/2005/12/1209_051209_crops_map.html 
7. ^ Somerville, John. 1981. Soviet Marxism and nuclear war : an international debate : from the proceedings of the special colloquium of the XVth World Congress of Philosophy. Greenwood Press. Pg.151
8. ^ Goodman, Lisl Marburg and Lee Ann Hoff. 1990. Omnicide: The Nuclear Dilemma. New York: Praeger.
9. ^ Landes, Daniel (ed.). 1991. Confronting Omnicide: Jewish Reflections on Weapons of Mass Destruction. Jason Aronson Publishers.
10. ^ Wilcox, Richard Brian. 2004. The Ecology of Hope: Environmental Grassroots Activism in Japan. Ph.D. Dissertation, Union Institute & University, College of Graduate Studies. Page 55.
11. ^ Jones, Adam (2006). "A Seminal Work on Genocide". Security Dialogue 37 (1): 143–144. doi:10.1177/0967010606064141 .
12. ^ Santoni, Ronald E. (1987). "Genocide, Nuclear Omnicide, and Individual Responsibility". Social Science Record 24 (2): 38–41.

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Further reading

• Cawthorne, N. (2004). Doomsday. Arcturus Publishing Limited. ISBN 1-84193-238-8
• Leslie, J. (1999). Risking Human Extinction 
• Leslie, J. (1996). The End of the World: The Science and Ethics of Human Extinction. Routledge. ISBN 0-415-18447-9
• Russell, J.D. (2008). Trojan Whores ~The Road to Armageddon~ a Prophetic Retrospective, by Jahred Kammen, the Last Liberal ISBN 978-0-615-19676-3.
• Global catastrophic risks and human extinction library 
• Eternal Fascinations with the End: Why We're Suckers for Stories of Our Own Demise: Our pattern-seeking brains and desire to be special help explain our fears of the apocalypse, by Michael Moyer August 18, 2010 Scientific American 
• Guterl, F. (2012), The Fate Of the Species . Bloomsbury USA, New York. ISBM 978-1-60819-258-8. Why the human race may cause its own extinction and how we can stop it.

"Soon a millennium will end. With it will pass four billion years of evolutionary exuberance. Yes, some species will survive, particularly the smaller, tenacious ones living in places far too dry and cold for us to farm or graze. Yet we must face the fact that the Cenozoic, the Age of Mammals which has been in retreat since the catastrophic extinctions of the late Pleistocene is over, and that the Anthropozoic or Catastrophozoic has begun." --Michael Soulè (1996) [Extinction is the gravest conservation problem of our era. Indeed, it is the gravest problem humans face. The following discussion is adapted from Chapters 1, 2, and 4 of Dave Foreman’s Rewilding North America.] Click Here For Full PDF Report...  or read Summary below... (Many of our reports are in Adobe Acrobat PDF Format.  If you don't already have one, the free Acrobat Reader can be downloaded by clicking this link.) The Crisis The most important—and gloomy—scientific discovery of the twentieth century was the extinction crisis. During the 1970s, field biologists grew more and more worried by population drops in thousands of species and by the loss of ecosystems of all kinds around the world. Tropical rainforests were falling to saw and torch. Wetlands were being drained for agriculture. Coral reefs were dying from god knows what. Ocean fish stocks were crashing. Elephants, rhinos, gorillas, tigers, polar bears, and other “charismatic megafauna” were being slaughtered. Frogs were vanishing. Even Leviathan—the great whales—were being hunted down in their last redoubts of the Antarctic and Arctic seas, and their end was in sight. These staggering losses were in oceans and on the highest peaks; they were in deserts and in rivers, in tropical rainforests and Arctic tundra alike.           A few biologists—including geneticist Michael Soulè (who was later the founder of the Society for Conservation Biology) and Harvard's famed E. O. Wilson—put these worrisome anecdotes and bits of data together. They knew, through paleontological research by others, that in the 570 million years or so of the evolution of modern animal phyla there had been five great extinction events. The last happened 65 million years ago, at the end of the Cretaceous when dinosaurs became extinct. Wilson and company calculated that the current rate of extinction is one thousand to ten thousand times the background rate of extinction in the fossil record. That discovery hit with all the subtlety of an asteroid striking Earth: RIGHT NOW, TODAY, LIFE FACES THE SIXTH GREAT EXTINCTION EVENT IN EARTH HISTORY. The cause is just as unsettling and unprecedented: eating, manufacturing, traveling, warring, consuming, and breeding by six billion human beings. For the first time in the history of life on Earth, one species is killing countless others. For the first time, one species—Homo sapiens; that's us—is waging a war against Nature. The crisis we face is biological meltdown. Wilson (1992) warns that the proportion of species driven to extinction “might easily reach 20 percent by 2022 and rise as high as 50 percent or more thereafter.” Soulè (1980) has said that soon the only large mammals left will be those we consciously choose to protect; that, “[The twentieth] century will see the end of significant evolution of large plants and terrestrial vertebrates in the tropics.” He writes (1996), “The end of speciation for most large animals rivals the extinction crisis in significance for the future of living nature. As [Bruce Wilcox and I] said in 1980, ‘Death is one thing, an end to birth is something else.’” Five Great Extinctions The fossil record reveals five great extinction episodes in the last half-billion years. They are: Ordovician—500 million years ago, 50 percent of animal families became extinct, including many trilobites (a dominant kind of marine organism that looked sort of like a horseshoe crab). Devonian—345 million years ago, 30 percent of animal families became extinct, including some types of early fishes. Permian—250 million years ago, 50 percent of animal families, 95 percent of marine species, many amphibians, and many trees became extinct. Triassic—180 million years ago, 35 percent of animal families became extinct, including many reptiles and marine mollusks. Cretaceous—65 million years ago, dinosaurs and many mollusks became extinct. The Three Waves of the Pleistocene-Holocene Extinction Event The First Wave: Spread of Modern Humans 40,000 years to 200 years BP Location Date Affected Species Europe and Northern Asia 40,000 to 13,000 BP Megafauna, including Homo neanderthalensis Australia and New Guinea 40,000 to 25,000 BP Large marsupials, reptiles, and birds North and South America 11,000 to 10,000 BP Megafauna Caribbean Islands 7,000 to 3,000 BP Giant ground sloths, monkeys, tortoises Mediterranean Islands 5,000 BP Dwarf megafauna, including elephants Wrangel Island (Siberian Arctic) 3,500 BP Mammoths Pacific Islands 3,000 to 200 BP (AD 1800) Birds New Zealand 1500 to 200 BP (AD 1800) Moas, other flightless birds Madagascar 1000 to 200 BP (AD 1800) Large birds, tortoises, lemurs, small hippos The Second Wave: Spread of Europeans 500 BP (AD 1500) to 30 BP (AD 1970) Islands Tortoises, birds, mammals Continents Freshwater taxa, and steep population declines of remaining megafauna Oceans Steep population declines of marine mammals, large fish, and other species The Third Wave: Overpopulation and Globalization AD 1970 to 2100 Everywhere All taxa (From Rewilding North America by Dave Foreman. Copyright © 2004 by the author. Reproduced by permission of Island Press, Washington, D.C.) The Causes And Processes Of Extinction Many things can push a species into the long, dark night of extinction. However, only a few things can cause mass extinction. For past mass extinctions, cataclysmic events—either terrestrial or extraterrestrial—so altered or harmed the biosphere that many species and whole groups of organisms died out. Scientists have found convincing evidence that the extinction of the dinosaurs 65 million years ago came suddenly (perhaps in a matter of days or weeks) when an asteroid struck Earth in a shallow sea where today's Yucatan Peninsula of Mexico lies.        But what causes “normal” extinctions, the kind that make up the background rate between the few big catastrophes? A species can become “extinct” by evolving into a new species or several new species (speciation driven by natural selection), or a species can become extinct by dying out and not continuing its evolutionary experiment. The latter is real extinction. Extinction, or evolution into daughter species, is the fate of all species. Careful study of the fossil record of marine invertebrates shows that species usually last for one million to ten million years. What may cause species to become extinct? Michael Soulè lists the possible factors: rarity (low density); rarity (small, infrequent patches); limited dispersal ability; inbreeding; loss of heterozygosity (genetic diversity); founder effects; hybridization; successional loss of habitat; environmental variation; long-term environmental trends (such as climate change); catastrophe; extinction or reduction of mutualist populations; competition; predation; disease; hunting and collecting; habitat disturbance; and habitat destruction. Soulè (1983) points out that some of these factors “do not become operative until one or more of the other factors have reduced the local populations to a very small size.” Note that he lumps the natural and human causes. Most of these factors are at play in today's mass extinction. Soulè warns, however, that “It is disappointing that we know so little about natural extinction.” Why does modern science know so little about this fascinating subject? It is because “no biologist has documented the extinction of a continental species of a plant or animal caused solely by nonhuman agencies.” The grim truth is that we humans are the cause of modern extinctions. How do we do it? Extinction expert David Wilcove and his colleagues list five anthropogenic causes of extinction in the United States, in order of current importance: habitat destruction; non-native (alien) species; pollution; overexploitation; disease. (Worldwide, however, overexploitation is far more important than in the United States today.) Here are a few examples of the ways humans cause extinction in each of these categories. Habitat Destruction. We reduce, modify, degrade, or transform natural habitat upon which species depend by burning, agricultural clearing, logging, mining, grazing by domestic animals, preventing natural fire, damming rivers, dewatering rivers through irrigation diversion, drying up springs and streams through groundwater pumping, eliminating keystone species like beaver and prairie dogs whose activities create habitat for other species, and urban and suburban development. Furthermore, we fragment habitat—thereby disrupting necessary patterns of movement of many species—through the above activities and by building roads, clearing power-line rights-of-way, and driving vehicles. Non-native (Alien) Species. As humans have spread into new lands, we have brought with us disruptive alien species that are generally well adapted to human disturbance and that outcompete native species, in part because their normal enemies, such as predators and diseases, are left behind. Such damaging invaders include plants and animals, both deliberately introduced species such as domestics or ornamentals, and accidentally introduced species such as weeds or pests. These non-native species include predators (cats, rats, pigs) and competitors (starlings, tamarisk, zebra mussels. Pollution. Pollution, whether localized or global (acid rain, greenhouse gases), can poison the waters and soils that are habitat for sensitive species, or leach away needed nutrients. Global warming and atmospheric ozone depletion—major threats to life forms worldwide—are caused largely by air pollution. Overexploitation. Hunting, fishing, trapping, collecting, and government “pest” eradication programs have caused the extinction of many species and seriously endanger others today. Disease. As humans have spread around the world, we have brought exotic diseases with us. Global trade is spreading many new diseases. An exotic disease caused the loss of the American chestnut in the wild. The black-footed ferret was nearly wiped out by canine distemper, a disease not native to the Americas. [The Ecological Wounds page on this website also looks at the human causes of extinction.] Ernst Mayr, perhaps the biological giant of the twentieth century, writes (2001): Background extinction and mass extinction are drastically different in most respects. Biological causes and natural selection are dominant in background extinction, whereas physical factors and chance are dominant in mass extinction. Species are involved in background extinction, and entire higher taxa in mass extinction. As the cause of today's mass extinction, we humans are no longer just a biological phenomenon, but are now a physical factor equivalent to an asteroid or continental drift in radically changing biological diversity. We are not exterminating only individual species, but “entire higher taxa.” The Three Waves of Extinction We can see the Sixth Great Extinction occurring in three waves, each caused by new groups of humans armed with new technologies spreading over new lands. The First Wave, the Spread of Modern Humans, ran from 40,000 to about 3,500 years ago as skilled big game hunters first entered lands where Homo sapiens had not previously existed. It continued from 3,000 years ago until 200 years ago, as Stone Age farmers found previously unpeopled islands in the Pacific and Indian oceans. The Second Wave, the Spread of Europeans, began in 1500 and ended around 1970 as European colonial and then industrial civilization spread over the world. The Third Wave, Overpopulation and Globalization, began about 1970 as human population exploded and new technologies and business practices tied the world into one exponentially expanding agro-techno-economy. In the First Wave, extinctions were caused mostly by hunting, and perhaps by fire-setting and introductions of dogs and diseases into areas that had not previously experienced them. The victims were primarily large mammals, birds, and reptiles on continents and islands. In the second phase of the First Wave, Stone Age farmers settled Hawaii, New Zealand, Madagascar, and other islands, and extinctions were caused by agricultural clearing, fire-setting, hunting, and introductions of dogs, rats, pigs, goats, and diseases into areas that had not previously experienced them. The victims were primarily birds and reptiles. The Second Wave was caused by hunting with guns; large-scale fishing; massive habitat destruction by agriculture, forestry, and domestic livestock grazing; river damming and diversion; introduction of exotic predators, browsers, grazers, parasites, and diseases; and later by industrial pollution. Islands lost birds, giant tortoises, and small mammals. On continents, some birds, fish, and large mammals have been driven into extinction, but many more species of birds, freshwater fish, and large mammals have had their numbers drastically reduced to possibly nonviable remnants. In the oceans, sea mammals, shellfish, and many fish have been wastefully exploited so that their populations are mere shadows of what they were 400 years ago. The Third Wave has just begun. Its agents of extinction are those of the other waves, but now the human population explosion—from about 10 million 10,000 years ago to over six billion today—and a globalized agro-techno-economy spread over the whole Earth threaten everything from the last megafauna to plants to insects to coral reef ecosystems. In 40,000 years, fully modern humans have spread across the Earth three times, with devastating consequences for the rest of life. The Evidence For Mass Extinction Today Even if we grudgingly acknowledge past human-caused extinctions, what proof is there that a mass extinction continues today? We can take at least three different tacks in answering this question. First is the area-species relationship and the evidence of habitat destruction. Second is the decline of specific living species. Third is the accounting of our takeover of Earth's terrestrial and marine net primary productivity (NPP) and our overshooting of ecological carrying capacity. Species-Area Relationship Michael Soulè writes (1999-2000), “One of the principles of modern ecology is that the number of species that an area can support is directly proportional to its size. A corollary is that if area is reduced, the number of species shrinks.” In 1980, John Terborgh and Blair Winter wrote that research showed that “extinction is strongly area dependent.” The species-area relationship has been shown with birds, mammals, reptiles, and other kinds of animals on the Greater Sunda Islands (the Indonesian archipelago), Caribbean islands, and elsewhere. An ecological rule of thumb is that if a habitat is cut by 90 percent, it will lose 50 percent of its species, or, if 50 percent of the area is lost, 10 percent of the species will disappear.   Known Loss of Species Another way of showing that mass extinction is real comes from looking at historic extinctions and the number of species that are in danger of extinction today. Let’s just consider mammals. In 1997, Ross MacPhee and Clare Flemming of the American Museum of Natural History Department of Mammalogy published the results of their careful review of mammal extinctions since 1500 AD. They identified 90 species of mammals that have become extinct during the modern era of European expansion, although they think it likely that the number will be “revised upward to 110 or 115 confirmed losses” or “close to 2 percent of all mammal species on Earth.” Using the highest estimate for the rate of natural or background extinction of one mammal species every 400 years, the loss of 90 species in 500 years is “a minimum 7,100 percent increase over the natural rate.” What of the near future? In 1995, 22 of Earth's 30 surviving species of large mammalian carnivores were listed as “endangered by either the United States or the World Conservation Union.” There are only some 2,000 breeding adult African wild dogs left in the wild, and the Ethiopian wolf is down “to fewer than 500 individuals.” According to the World Wildlife Fund, there may be no more than 1,000 giant pandas left in the wild. BBC News reports that “India's Minister of Social Justice and Empowerment has warned that by 2007 ‘there would be no breeding elephants left in India…and the species would die out’” because of poaching, capturing, and habitat destruction. Ten percent of the 608 species and subspecies of primates are in grave and immediate danger of extinction. Cambridge University's primatologist David Chivers says, “I've spent 30 years on [primate conservation], and now we don't seem to be getting anywhere. It's ridiculous.”   Net Primary Productivity The third area of evidence for the reality of mass extinction is to add up humans’ impact. But is it really possible to calculate the human impact on Earth? Actually, we can, and we can even put a number on it. A group at Stanford University, including Paul and Anne Erhlich, published the results of their research in BioScience that showed human beings were using about 40 percent of Earth's Net Primary Productivity (NPP) in 1986. This basic ecological measure is defined by Paul and Anne Ehrlich as “[a]ll the solar energy annually captured worldwide by photosynthesizers and not used by them to run their own lives.” The Stanford group's calculations were strongly confirmed in 2001 by Stuart Pimm with his book, The World According to Pimm: a scientist audits the Earth. Pimm gives a detailed accounting of our appropriation of Net Primary Productivity. Forty percent is how much of NPP we are taking now with 6 billion humans. However, we continue to pile baby upon baby. The exponential growth of human population multiplied by rising affluence and more invasive technology is the main driver of the Third Wave of Extinction. Where will it all end? Many demographers predict that human population will stabilize at 11-12 billion—twice what it is today. If we double our population, and affluence and technology continue to increase as world leaders, corporate heads, and economists believe, what becomes of our taking of NPP? Double our population and we will take over 80 percent. This is conservative because it does not incorporate increasing affluence and technology. Is this sustainable? How many species could continue to exist on less than 20 percent of the Net Primary Productivity? Clearly an ecological crash will happen before we reach this point. (From Rewilding North America by Dave Foreman [chapters 1, 2, and 4]. Copyright © 2004 by the author. Reproduced by permission of Island Press, Washington, D.C. Except for some direct quotes, references in the book have been deleted here. Any citations given are from the books and papers below. http://www.wisegeek.com/what-is-the-sixth-mass-extinction.htm The Sixth Mass Extinction, also known as the Sixth Extinction or the Holocene extinction event, is an ongoing extinction event perpetrated by human beings. It began about 50,000 years ago, when modern man first left Africa. Since then, it seems to have been nothing but havoc. At least 20,000 species have gone extinct at the hands of humans, and possibly far more. Terrestrial species have had it the worst, as that is where human influence is strongest. First, from about 50,000 to 20,000 years ago, dozens of species of megafauna -- large animals such as mammoths, saber-toothed tigers, the Dire Wolf, cave bears, and many others -- went extinct shortly after humans started moving in on their territory. These are called the Pleistocene megafaunal extinctions, and represent the first phase of the Sixth Mass Extinction. Climate change is sometimes advanced as a cause for their extinctions, but this argument bears little weight, as the animals in question survived numerous glacial and interglacial periods before going extinct soon after the arrival of humans, which happened to occur shortly after the end of the last glacial period. The Sixth Mass Extinction occurred as humans spread from continent to continent. First in Eurasia, then in Australia, then the Americas. Precious species, such as the Elephant Bird of Madagascar and Haast's Eagle in New Zealand went extinct relatively recently, around 1500 BCE, after the arrival of European explorers. Even animals that had unpalatable flesh, like the Dodo of Mauritus, were killed, mostly for sport. Unhelpful especially for island animals is their docile temperament, a result of living for thousands or even millions of years without major predators. The Sixth Mass Extinction has especially accelerated in the last 60 years, from the middle of the 20th century and into the 21st. Destruction of habitat and the introduction of invasive species such as rats, dogs, and cats have resulted in the mass extinction of numerous animals, especially island species. These invasive species, bred in the intense competition of Continental life, easily dispatch island species. Eradication programs of invasive species undertaken very recently, only in the last few decades, have preserved some species on the brink of extinction. In many ways, the Sixth Mass Extinction is different than the previous five mass extinctions. For instance, the Sixth Mass Extinction is the first known mass extinction to be caused by a species, especially a single species, rather than through abiotic natural causes such as volcanism or asteroid impact. It is also characterized by its relatively fast timescale of action, especially when referring to the last 60 years. Though some mass extinctions occurred in 10,000 years or less, and the Cretaceous-Tertiary extinction that wiped out the dinosaurs occurred very rapidly, the Sixth Mass Extinction is faster than most of the others. If we wish to stop this Sixth Mass Extinction, we have to make conservation a top priority, reflecting it in our actions and votes. http://www.ucmp.berkeley.edu/quaternary/holocene.phpOnline exhibits : Geologic time scale : Cenozoic Era The Holocene Epoch To observe a Holocene environment, simply look around you! The Holocene is the name given to the last 11,700 years* of the Earth's history — the time since the end of the last major glacial epoch, or "ice age." Since then, there have been small-scale climate shifts — notably the "Little Ice Age" between about 1200 and 1700 A.D. — but in general, the Holocene has been a relatively warm period in between ice ages. Another name for the Holocene that is sometimes used is the Anthropogene, the "Age of Man." This is somewhat misleading: humans of our own subspecies, Homo sapiens, had evolved and dispersed all over the world well before the start of the Holocene. Yet the Holocene has witnessed all of humanity's recorded history and the rise and fall of all its civilizations. Humanity has greatly influenced the Holocene environment; while all organisms influence their environments to some degree, few have ever changed the globe as much, or as fast, as our species is doing. The vast majority of scientists agree that human activity is responsible for "global warming," an observed increase in mean global temperatures that is still going on. Habitat destruction, pollution, and other factors are causing an ongoing mass extinction of plant and animal species; according to some projections, 20% of all plant and animal species on Earth will be extinct within the next 25 years. Yet the Holocene has also seen the great development of human knowledge and technology, which can be used — and are being used — to understand the changes that we see, to predict their effects, and to stop or ameliorate the damage they may do to the Earth and to us. Paleontologists are part of this effort to understand global change. Since many fossils provide data on climates and environments of the past, paleontologists are contributing to our understanding of how future environmental change will affect the Earth's life. Resources Get the latest on global warming from NOAA's global warming update, or peruse NASA's Global Change Master Directory. Browse abstracts of the latest Holocene research in the Journal of Paleolimnology or the Holocene Journal. Learn more through the Quaternary Research Association.