Extinction of the Human Species.

35 - Origins and analysis of extinction hypotheses.   As a result of the extensive nuclear fallout of the 1954 Castle Bravo nuclear detonation, author Nevil Shute wrote the popular novel On the Beach, released in 1957. In this novel, so much fallout is generated in a nuclear war that all human life is extinguished. However, the premise that all of humanity would die following a nuclear war and onl...

34 - Nuclear famine.   It is difficult to estimate the number of casualties that would result from nuclear winter, but it is likely that the primary effect would be global famine (known as nuclear famine), wherein mass starvation occurs due to disrupted agricultural production and distribution. In 2013 and 2022 reports, the International Physicians for the Prevention of Nuclear War (IPPNW) voiced...

33 - Effects of nuclear war.   Historically, it has been difficult to estimate the total number of deaths resulting from a global nuclear exchange because scientists are continually discovering new effects of nuclear weapons, and also revising existing models.   Early reports considered direct effects from nuclear blast and radiation and indirect effects from economic, social, and political disrup...

32 - Likelihood of complete human extinction.   Many scholars have posited that a global thermonuclear war with Cold War-era stockpiles, or even with the current smaller stockpiles, may lead to human extinction. This position was bolstered when nuclear winter was first conceptualized and modelled in 1983. However, models from the past decade consider total extinction very unlikely, and suggest par...

31 - Likelihood of nuclear war.   As of 2021, humanity has about 13,410 nuclear weapons, thousands of which are on hair-trigger alert. While stockpiles have been on the decline following the end of the Cold War, every nuclear country is currently undergoing modernization of its nuclear arsenal. The Bulletin advanced their symbolic Doomsday Clock in 2015, citing among other factors "a nuclear arms...

30 - Nuclear Holocaust.   A nuclear holocaust, also known as a nuclear apocalypse, nuclear annihilation, nuclear armageddon, or atomic holocaust, is a theoretical scenario where the mass detonation of nuclear weapons causes widespread destruction and radioactive fallout, with global consequences. Such a scenario envisages large parts of the Earth becoming uninhabitable due to the effects of nuclea...

29 - Ethics.   Value of human life.   "Existential risks" are risks that threaten the entire future of humanity, whether by causing human extinction or by otherwise permanently crippling human progress. Multiple scholars have argued, based on the size of the "cosmic endowment," that because of the inconceivably large number of potential future lives that are at stake, even small reductions of exis...

28 - Probability.   From nuclear weapons.   On November 13, 2024, the American Enterprise Institute estimated a probability of nuclear war during the 21st century between 0% and 80%. A 2023 article of The Economist estimated an 8% chance of nuclear war causing global catastrophe and a 0.5625% chance of nuclear war causing human extinction.   From supervolcanic eruption.   On November 13, 2024, the...

27 - Risk estimates.   Given the limitations of ordinary observation and modeling, expert elicitation is frequently used instead to obtain probability estimates.   Humanity has a 95% probability of being extinct in 8,000,000 years, according to J. Richard Gott's formulation of the controversial doomsday argument, which argues that we have probably already lived through half the duration of human h...

26 - Probability.   Natural vs. anthropogenic.   Experts generally agree that anthropogenic existential risks are (much) more likely than natural risks. A key difference between these risk types is that empirical evidence can place an upper bound on the level of natural risk. Humanity has existed for at least 200,000 years, over which it has been subject to a roughly constant level of natural risk...

25 - Atomic era.   The invention of the atomic bomb prompted a wave of discussion among scientists, intellectuals, and the public at large about the risk of human extinction. In a 1945 essay, Bertrand Russell stated:  The prospect for the human race is sombre beyond all precedent. Mankind are faced with a clear-cut alternative: either we shall all perish, or we shall have to acquire some slight de...

24 - Human Extinction.   Human extinction, or omnicide, is the hypothetical end of the human species, either by population decline due to extraneous natural causes, for example asteroid impact or large-scale volcanism, or via anthropogenic destruction (self-extinction).   Some of the many possible contributors to anthropogenic hazards are climate change, global nuclear annihilation, biological war...

23 - Influence on Policy, Philosophy, and Public Debate.   Concerns over human extinction risks have prompted discussions in international policy forums, particularly regarding artificial intelligence (AI) safety and nuclear weapons. In May 2023, a statement signed by hundreds of AI experts, including leaders from OpenAI and Google DeepMind, equated mitigating AI extinction risks with addressing p...

22 - Representations in Culture and Discourse.   Fictional Depictions and Popular Media.   Fictional depictions of human extinction predominantly appear in science fiction, serving as allegories for existential risks such as nuclear war, pandemics, and technological overreach, though total species annihilation is often implied rather than directly narrated due to storytelling constraints requiring...

21 - Societal Adaptation and Long-Term Planning.   Societal adaptation to existential risks requires institutional reforms that extend decision-making horizons beyond electoral cycles and immediate economic pressures, fostering resilience through diversified infrastructure, robust governance, and cultural emphasis on intergenerational equity. Longtermism, a view advanced within effective altruism...

20 - Technological Innovations and Defensive Measures.   Technological innovations aimed at mitigating existential risks to humanity include advancements in planetary defense, artificial intelligence safety, and biosecurity protocols, which seek to address threats such as asteroid impacts, uncontrolled AI development, and engineered pandemics. These efforts emphasize kinetic impactors for celestia...

19 - Strategies for Risk Reduction and Resilience.   Governance and International Safeguards.   International governance mechanisms addressing existential risks from human extinction focus on specific threats like nuclear war, engineered pandemics, and emerging technologies such as artificial intelligence, though comprehensive frameworks remain limited by enforcement gaps, non-universal participat...

18 - Fringe Perspectives: Voluntary Extinction Advocacy.   The Voluntary Human Extinction Movement (VHEMT) advocates for the gradual, voluntary phase-out of the human species through the cessation of reproduction, positing that this would allow Earth's biosphere to recover from anthropogenic damage. Founded in 1991 by Les U. Knight, an American environmental activist born around 1947 in Oregon, th...

17 - Critiques of Extinction Alarmism and Overprediction.   Critics of extinction alarmism argue that predictions of imminent human extinction from anthropogenic risks, such as climate change, artificial intelligence, or pandemics, often rely on speculative models that overestimate tail-end probabilities while underestimating human adaptability and technological mitigation. For instance, historica...

16 - Obligations to Future Generations from First Principles.   From foundational ethical reasoning, obligations to future generations arise from the recognition that human actions causally determine whether potential persons will exist and experience lives of positive value. If individual human lives possess intrinsic worth—grounded in capacities for welfare, agency, and flourishing—then extingui...

15 - Ethical and Normative Dimensions.   Intrinsic Value of Human Continuity,   The intrinsic value of human continuity refers to the moral worth inherent in the sustained existence of Homo sapiens as a species characterized by sentience, consciousness, and rational agency, independent of any derivative benefits such as technological progress or ecological services. Philosophers analyzing existent...

14 - Comparative Risk Profiles: Natural vs. Anthropogenic.   Natural risks to human extinction, such as asteroid impacts, supervolcanic eruptions, and natural pandemics, have historically exhibited extremely low probabilities, estimated at approximately 1 in 10,000 over the next century. These risks stem from exogenous cosmic or geological events that humanity has endured without extinction for ov...

13 - Empirical Data and Historical Analogues.   Genomic analyses indicate that human ancestors experienced a severe population bottleneck approximately 930,000 to 813,000 years ago, reducing the effective breeding population to around 1,280 individuals for roughly 117,000 years, though subsequent studies have questioned the severity due to potential modeling artifacts. This event, coinciding with...

12 - Probability Estimation and Uncertainty.   Methodological Foundations and Challenges.   The methodological foundations for estimating human extinction probabilities draw from probabilistic risk assessment techniques adapted to existential scales, including expert elicitation, reference class forecasting, and causal decomposition modeling. Expert elicitation involves surveying domain specialist...

11 - Emerging Technological Hazards.   Emerging technological hazards encompass risks from developing fields such as molecular nanotechnology and high-energy particle physics experiments, where unintended consequences could theoretically cascade to global scales, potentially causing human extinction through mechanisms like uncontrolled matter conversion or physical phase transitions. These differ...