A global catastrophic risk or a doomsday scenario is a hypothetical future event that could damage human well-being on a global scale, even endangering or destroying modern civilization. An event that could cause

human extinction Human extinction, also known as omnicide, is the hypothetical end of the human species due to either natural causes such as population decline from sub-replacement fertility, an asteroid impact, or large-scale volcanism, or to anthropogenic ...

or permanently and drastically curtail humanity's potential is known as an "existential risk." Over the last two decades, a number of academic and non-profit organizations have been established to research global catastrophic and existential risks, formulate potential mitigation measures and either advocate for or implement these measures.

Definition and classification

Defining global catastrophic risks

The term global catastrophic risk "lacks a sharp definition", and generally refers (loosely) to a risk that could inflict "serious damage to human well-being on a global scale". Humanity has suffered large catastrophes before. Some of these have caused serious damage but were only local in scope—e.g. the

Black Death The Black Death (also known as the Pestilence, the Great Mortality or the Plague) was a bubonic plague pandemic occurring in Western Eurasia and North Africa from 1346 to 1353. It is the most fatal pandemic recorded in human history, causi ...

may have resulted in the deaths of a third of Europe's population, 10% of the global population at the time. Some were global, but were not as severe—e.g. the

1918 influenza pandemic The 1918–1920 influenza pandemic, commonly known by the misnomer Spanish flu or as the Great Influenza epidemic, was an exceptionally deadly global influenza pandemic caused by the H1N1 influenza A virus. The earliest documented case was ...

killed an estimated 3–6% of the world's population. Most global catastrophic risks would not be so intense as to kill the majority of life on earth, but even if one did, the ecosystem and humanity would eventually recover (in contrast to ''existential risks''). Similarly, in '' Catastrophe: Risk and Response'',

Richard Posner Richard Allen Posner (; born January 11, 1939) is an American jurist and legal scholar who served as a federal appellate judge on the U.S. Court of Appeals for the Seventh Circuit from 1981 to 2017. A senior lecturer at the University of Chic ...

singles out and groups together events that bring about "utter overthrow or ruin" on a global, rather than a "local or regional", scale. Posner highlights such events as worthy of special attention on cost–benefit grounds because they could directly or indirectly jeopardize the survival of the human race as a whole.

Defining existential risks

Existential risks are defined as "risks that threaten the destruction of humanity's long-term potential." The instantiation of an existential risk (an ''existential catastrophe'') would either cause outright human extinction or irreversibly lock in a drastically inferior state of affairs. Existential risks are a sub-class of global catastrophic risks, where the damage is not only ''global'' but also ''terminal'' and ''permanent,'' preventing recovery and thereby affecting both current and all future generations.

Non-extinction risks

While extinction is the most obvious way in which humanity's long-term potential could be destroyed, there are others, including ''unrecoverable'' ''collapse'' and ''unrecoverable'' ''dystopia''. A disaster severe enough to cause the permanent, irreversible collapse of human civilisation would constitute an existential catastrophe, even if it fell short of extinction. Similarly, if humanity fell under a totalitarian regime, and there were no chance of recovery then such a dystopia would also be an existential catastrophe.Bryan Caplan (2008).
The totalitarian threat
. ''Global Catastrophic Risks'', eds. Bostrom & Cirkovic (Oxford University Press): 504–519.

Bryan Caplan Bryan Douglas Caplan (born April 8, 1971) is an American economist and author. Caplan is a professor of economics at George Mason University, research fellow at the Mercatus Center, adjunct scholar at the Cato Institute, and former contributor ...

writes that "perhaps an eternity of totalitarianism would be worse than extinction". (

George Orwell Eric Arthur Blair (25 June 1903 – 21 January 1950), better known by his pen name George Orwell, was an English novelist, essayist, journalist, and critic. His work is characterised by lucid prose, social criticism, opposition to totalit ...

's novel ''

Nineteen Eighty-Four ''Nineteen Eighty-Four'' (also stylised as ''1984'') is a dystopian social science fiction novel and cautionary tale written by the English writer George Orwell. It was published on 8 June 1949 by Secker & Warburg as Orwell's ninth and fina ...

'' suggests an example.) A dystopian scenario shares the key features of extinction and unrecoverable collapse of civilisation—before the catastrophe, humanity faced a vast range of bright futures to choose from; after the catastrophe, humanity is locked forever in a terrible state.

Potential sources of risk

Potential global catastrophic risks are conventionally classified as anthropogenic or non-anthropogenic hazards. Examples of non-anthropogenic risks are an asteroid

impact event An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or ...

, a supervolcanic

eruption Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often ...

, a lethal gamma-ray burst, a

geomagnetic storm A geomagnetic storm, also known as a magnetic storm, is a temporary disturbance of the Earth's magnetosphere caused by a solar wind shock wave and/or cloud of magnetic field that interacts with the Earth's magnetic field. The disturbance that d ...

destroying electronic equipment, natural long-term

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

, hostile

extraterrestrial life Extraterrestrial life, colloquially referred to as alien life, is life that may occur outside Earth and which did not originate on Earth. No extraterrestrial life has yet been conclusively detected, although efforts are underway. Such life might ...

, or the predictable

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

transforming into a

red giant star A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around or ...

engulfing the Earth. Anthropogenic risks are those caused by humans and include those related to technology, governance, and climate change. Technological risks include the creation of

artificial intelligence Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech ...

misaligned with human goals,

biotechnology Biotechnology is the integration of natural sciences and engineering sciences in order to achieve the application of organisms, cells, parts thereof and molecular analogues for products and services. The term ''biotechnology'' was first used ...

, and

nanotechnology Nanotechnology, also shortened to nanotech, is the use of matter on an atomic, molecular, and supramolecular scale for industrial purposes. The earliest, widespread description of nanotechnology referred to the particular technological goal ...

. Insufficient or malign

global governance Global governance refers to institutions that coordinate the behavior of transnational actors, facilitate cooperation, resolve disputes, and alleviate collective action problems. Global governance broadly entails making, monitoring, and enfor ...

creates risks in the social and political domain, such as

global war A world war is an international conflict which involves all or most of the world's major powers. Conventionally, the term is reserved for two major international conflicts that occurred during the first half of the 20th century, World WarI (1914 ...

and

nuclear holocaust A nuclear holocaust, also known as a nuclear apocalypse, nuclear Armageddon, or atomic holocaust, is a theoretical scenario where the mass detonation of nuclear weapons causes globally widespread destruction and radioactive fallout. Such a scenar ...

bioterrorism Bioterrorism is terrorism involving the intentional release or dissemination of biological agents. These agents are bacteria, viruses, insects, fungi, and/or toxins, and may be in a naturally occurring or a human-modified form, in much the same ...

using

genetically modified organism A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques. The exact definition of a genetically modified organism and what constitutes genetic engineering varies, wit ...

cyberterrorism Cyberterrorism is the use of the Internet to conduct violent acts that result in, or threaten, the loss of life or significant bodily harm, in order to achieve political or ideological gains through threat or intimidation. Acts of deliberate, la ...

destroying

critical infrastructure Critical infrastructure (or critical national infrastructure (CNI) in the UK) is a term used by governments to describe assets that are essential for the functioning of a society and economy – the infrastructure. Most commonly associated w ...

like the

electrical grid An electrical grid is an interconnected network for electricity delivery from producers to consumers. Electrical grids vary in size and can cover whole countries or continents. It consists of:Kaplan, S. M. (2009). Smart Grid. Electrical Power ...

, or the failure to manage a natural or engineered

pandemic A pandemic () is an epidemic of an infectious disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of individuals. A widespread endemic disease with a stable number of in ...

. Global catastrophic risks in the domain of earth system governance include

global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

environmental degradation Environmental degradation is the deterioration of the environment through depletion of resources such as quality of air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife; and pollution. It is defin ...

, extinction of species,

famine A famine is a widespread scarcity of food, caused by several factors including war, natural disasters, crop failure, population imbalance, widespread poverty, an economic catastrophe or government policies. This phenomenon is usually accompan ...

as a result of non-equitable resource distribution,

human overpopulation Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...

crop failures Harvesting is the process of gathering a ripe crop from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper. On smaller farms with minimal mechanization, harvesting is the most labor- ...

, and non-

sustainable agriculture Sustainable agriculture is farming in sustainable ways meeting society's present food and textile needs, without compromising the ability for current or future generations to meet their needs. It can be based on an understanding of ecosystem ser ...

Methodological challenges

Research into the nature and mitigation of global catastrophic risks and existential risks is subject to a unique set of challenges and, as a result, is not easily subjected to the usual standards of scientific rigour. For instance, it is neither feasible nor ethical to study these risks experimentally.

Carl Sagan Carl Edward Sagan (; ; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist, cosmologist, astrophysicist, astrobiologist, author, and science communicator. His best known scientific contribution is research on ex ...

expressed this with regards to nuclear war: "Understanding the long-term consequences of nuclear war is not a problem amenable to experimental verification". Moreover, many catastrophic risks change rapidly as technology advances and background conditions, such as geopolitical conditions, change. Another challenge is the general difficulty of accurately predicting the future over long timescales, especially for anthropogenic risks which depend on complex human political, economic and social systems. In addition to known and tangible risks, unforeseeable

black swan The black swan (''Cygnus atratus'') is a large waterbird, a species of swan which breeds mainly in the southeast and southwest regions of Australia. Within Australia, the black swan is nomadic, with erratic migration patterns dependent upon ...

extinction events may occur, presenting an additional methodological problem.

Lack of historical precedent

Humanity has never suffered an existential catastrophe and if one were to occur, it would necessarily be unprecedented. Therefore, existential risks pose unique challenges to prediction, even more than other long-term events, because of observation selection effects. Unlike with most events, the failure of a complete

extinction event An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. I ...

to occur in the past is not evidence against their likelihood in the future, because every world that has experienced such an extinction event has no observers, so regardless of their frequency, no civilization observes existential risks in its history. These

anthropic {{Short pages monitor''The Collapse of Complex Societies'',

Cambridge University Press Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by King Henry VIII in 1534, it is the oldest university press in the world. It is also the King's Printer. Cambridge University Pr ...

, Cambridge, UK (). *

Martin Rees Martin John Rees, Baron Rees of Ludlow One or more of the preceding sentences incorporates text from the royalsociety.org website where: (born 23 June 1942) is a British cosmologist and astrophysicist. He is the fifteenth Astronomer Royal, ...

(2004). '' Our Final Hour: A Scientist's warning: How Terror, Error, and Environmental Disaster Threaten Humankind's Future in This Century—On Earth and Beyond''. * Roger-Maurice Bonnet and

Lodewijk Woltjer Lodewijk Woltjer (26 April 1930 – 25 August 2019) was an astronomer, and the son of astronomer Jan Woltjer. He studied at the University of Leiden under Jan Oort earning a PhD in astronomy in 1957 with a thesis on the Crab Nebula. This was foll ...

, ''Surviving 1,000 Centuries Can We Do It?'' (2008), Springer-Praxis Books. *

Toby Ord Toby David Godfrey Ord (born July 1979) is an Australian philosopher. He founded Giving What We Can in 2009, an international society whose members pledge to donate at least 10% of their income to effective charities, and is a key figure in the ...

(2020)
The Precipice - Existential Risk and the Future of Humanity
Bloomsbury Publishing.

External links

* *

from ''

The Guardian ''The Guardian'' is a British daily newspaper. It was founded in 1821 as ''The Manchester Guardian'', and changed its name in 1959. Along with its sister papers '' The Observer'' and '' The Guardian Weekly'', ''The Guardian'' is part of the ...

''. Ten scientists name the biggest dangers to Earth and assess the chances they will happen. April 14, 2005.
Humanity under threat from perfect storm of crises – study
''The Guardian''. February 6, 2020.
Annual Reports on Global Risk
by the Global Challenges Foundation
Center on Long-Term Risk

Global Catastrophic Risk Policy
* {{Authority control Survivalism