Nuclear holocaust

{{Short description|Scenario of civilization collapse or human extinction  by nuclear weapons}}
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[[Image:Castle Bravo Blast.jpg|thumb|250px|Mushroom cloud from the 1954 explosion of [[Castle Bravo]], the largest nuclear weapon detonated by the U.S.]]
A '''nuclear holocaust''', also known as a '''nuclear apocalypse''', '''nuclear annihilation''', '''nuclear [[Armageddon|armageddon]]''', or '''atomic holocaust''', is a [[Futures studies|theoretical scenario]] where the mass detonation of [[nuclear weapons]] causes widespread destruction and [[radioactive]] fallout. Such a scenario envisages large parts of the Earth becoming uninhabitable due to the effects of [[nuclear warfare]], potentially causing the [[Societal collapse|collapse of civilization]], the [[extinction of humanity]], and/or [[Extinction event|the termination of most biological life on Earth]].

Besides the immediate destruction of cities by nuclear blasts, the potential aftermath of a nuclear war could involve [[firestorm]]s, a [[nuclear winter]], widespread [[Acute radiation syndrome|radiation sickness]] from [[Nuclear fallout|fallout]], and/or the temporary (if not permanent) loss of much modern technology due to [[electromagnetic pulse]]s. Some scientists, such as [[Alan Robock]], have speculated that a thermonuclear war could result in the end of modern civilization on [[Earth]], in part due to a long-lasting nuclear winter. In one model, the average temperature of Earth following a full thermonuclear war falls for several years by 7 – 8&nbsp;°C (13 to 15 degrees Fahrenheit) on average.<ref name="RobockSAD">{{cite journal |last1=Robock |first1=Alan |last2=Toon |first2=Owen B |title=Self-assured destruction: The climate impacts of nuclear war |journal=Bulletin of the Atomic Scientists |date=2012 |volume=68 |issue=5 |pages=66–74 |doi=10.1177/0096340212459127 |bibcode=2012BuAtS..68e..66R |s2cid=14377214 |url=http://thebulletin.org/2012/september/self-assured-destruction-climate-impacts-nuclear-war |access-date=13 February 2016 |archive-date=2 April 2020 |archive-url=https://web.archive.org/web/20200402175725/http://thebulletin.org/2012/september/self-assured-destruction-climate-impacts-nuclear-war |url-status=dead }}</ref>

Early [[Cold War]]-era studies suggested that billions of humans would survive the immediate effects of nuclear blasts and radiation following a global thermonuclear war.<ref name="bmartin.cc">{{cite journal |url=http://www.bmartin.cc/pubs/82jpr.html |doi=10.1177/002234338201900401 |title=Critique of Nuclear Extinction |author= Martin, Brian |journal=Journal of Peace Research |volume=19 |issue=4 |year= 1982 |pages=287–300|s2cid=110974484 }}</ref><ref>[http://www.johnstonsarchive.net/nuclear/nuclearwar1.html The Effects of a Global Thermonuclear War]. Johnstonsarchive.net. Retrieved on 2013-07-21.</ref><ref name="ReferenceB">{{cite journal |url=http://www.bmartin.cc/pubs/82cab/index.html |title=The global health effects of nuclear war |journal=Current Affairs Bulletin |volume=59 |issue=7 |date=December 1982 |pages=14–26 |author=Martin, Brian }}</ref><ref>{{cite book |url=https://trove.nla.gov.au/version/25667274 |title=Long-term worldwide effects of multiple nuclear-weapons detonations |first=National Research Council |last=Detonations |date=16 November 1975 |publisher=Washington : National Academy of Sciences |access-date=16 November 2018 |via=Trove |isbn=9780309024181}}</ref> The [[International Physicians for the Prevention of Nuclear War]] believe that nuclear war could indirectly contribute to human extinction via secondary effects, including environmental consequences, [[societal collapse|societal breakdown]], and economic collapse.

The threat of a nuclear holocaust plays an important role in the [[Nuclear weapons in popular culture|popular perception of nuclear weapons]]. It features in the security concept of [[Mutual assured destruction|mutually assured destruction]] (MAD) and is a common scenario in [[survivalism]]. Nuclear holocaust is a [[List of nuclear holocaust fiction|common feature in literature and film]], especially in [[speculative fiction|speculative genres]] such as [[science fiction]], [[dystopia]]n and [[Apocalyptic and post-apocalyptic fiction|post-apocalyptic fiction]].<ref>{{Cite web|url=https://brians.wsu.edu/supplementary-checklist/|title = Nuclear Holocausts: Atomic War in Fiction &#124; Common Errors in English Usage and More &#124; Washington State University}}</ref>
{{nuclear weapons}}

==Etymology and usage==
The English word "holocaust", derived from the [[Greek language|Greek]] term "holokaustos" meaning "completely burnt", refers to great destruction and loss of life, especially by fire.<ref name="AmHeritage">{{cite web|url=http://www.thefreedictionary.com/holocaust|title=holocaust|access-date=16 November 2018|via=The Free Dictionary}}</ref><ref>{{cite web|url=http://www.oxforddictionaries.com/us/definition/american_english/holocaust|archive-url=https://web.archive.org/web/20130606013221/http://oxforddictionaries.com/us/definition/american_english/holocaust|url-status=dead|archive-date=June 6, 2013|title=holocaust – Definition of holocaust in US English by Oxford Dictionaries|website=Oxford Dictionaries – English|access-date=16 November 2018}}</ref>

One early use of the word "holocaust" to describe an imagined nuclear destruction appears in Reginald Glossop's 1926 novel ''The Orphan of Space'': "Moscow ... beneath them  ... a crash like a crack of Doom! The echoes of this Holocaust rumbled and rolled ... a distinct smell of sulphur ... atomic destruction."<ref>Reginald Glossop, The Orphan of Space (London: G. MacDonald, 1926), pp. 303–306.</ref> In the novel, an atomic weapon is planted in the office of the Soviet dictator, who, with German help and Chinese mercenaries, is preparing the takeover of Western Europe.

==Likelihood of nuclear war==
{{See also|World War III#Historical close calls}}
[[File:World nuclear weapons.svg|thumb|Large stockpile with global range (dark blue), smaller stockpile with global range (medium blue), small stockpile with regional range (light blue)]]
As of 2021, humanity has about 13,410 nuclear weapons, thousands of which are on [[De-alerting|hair-trigger alert]].<ref>{{cite web|title=Status of World Nuclear Forces|url= https://fas.org/issues/nuclear-weapons/status-world-nuclear-forces/ |website=Federation of American Scientists|access-date=26 April 2020}}</ref><ref>{{cite web|title=Fact Sheet: Building Global Security by Taking Nuclear Weapons off Hair-Trigger Alert|url=http://www.nti.org/analysis/articles/fact-sheet-building-global-security-taking-nuclear-weapons-hair-trigger-alert/|publisher=[[National Threat Initiative]]|access-date=22 March 2016|date=15 October 2012}}</ref><!-- technically the NTI report is 2012, but if thousands of missiles were known to go off high alert in the past 4 years it would've made the news --> While stockpiles have been on the decline following the end of the Cold War, every [[List of states with nuclear weapons|nuclear country]] is currently undergoing modernization of its nuclear arsenal.<ref>{{cite news|last1=Broad|first1=William J|title=U.S. Ramping Up Major Renewal in Nuclear Arms|url=https://www.nytimes.com/2014/09/22/us/us-ramping-up-major-renewal-in-nuclear-arms.html?_r=0|newspaper=New York Times|access-date=24 January 2016|date=2014-09-21}}</ref><ref>{{cite news|author1=Mecklin, John|title=Disarm and Modernize|url=https://foreignpolicy.com/2015/03/24/disarm-and-modernize-nuclear-weapons-warheads/|access-date=22 March 2016|date=4 March 2015}}</ref><ref>{{cite journal|last1=Kristensen|first1=H. M.|last2=Norris|first2=R. S.|title=Slowing nuclear weapon reductions and endless nuclear weapon modernizations: A challenge to the NPT|journal=Bulletin of the Atomic Scientists|date=20 June 2014|volume=70|issue=4|pages=94–107|doi=10.1177/0096340214540062|bibcode=2014BuAtS..70d..94K|s2cid=145122829}}</ref> The ''Bulletin'' advanced their symbolic [[Doomsday Clock]] in 2015, citing among other factors "a nuclear arms race resulting from modernization of huge arsenals".<ref>{{cite news |last1=Rhodan |first1=Maya |title=4 Times the World Came Close to 'Doomsday' |url=https://time.com/4193889/doomsday-clock-changed-2016/ |access-date=24 May 2020 |magazine=Time |date=January 2016 |language=en}}</ref> In January 2020, it was moved forward to 100 seconds before midnight.<ref name=james>{{cite web | last=James | first=Sara | title='If there's ever a time to wake up, it's now': Doomsday Clock moves 20-seconds closer to midnight | website=ABC News |publisher =Australian Broadcasting Corporation | url=https://www.abc.net.au/news/2020-01-24/doomsday-clock-moves-closest-to-midnight-in-73-year-history/11896294 | access-date=January 24, 2020|date=January 24, 2020}}</ref> In 2023, it was moved forward to 90 seconds before midnight.

[[John F. Kennedy]] estimated the probability of the [[Cuban Missile Crisis]] escalating to nuclear conflict as between 33% and 50%.<ref>{{cite journal |last=Allison |first=Graham |year=2012 |title=The Cuban Missile Crisis at 50 |url=http://www.foreignaffairs.com/articles/137679/graham-allison/the-cuban-missile-crisis-at-50 |journal=[[Foreign Affairs]] |volume=91 |issue=4 |access-date=9 July 2012}}</ref><ref>{{cite web|url=http://www.vzglyad.ru/opinions/2013/11/22/660828.html|title=ВЗГЛЯД / "США и Россия: кризис 1962–го"|publisher=vzglyad.ru|date=22 November 2013|access-date=29 January 2016|archive-date=14 December 2013|archive-url=https://web.archive.org/web/20131214084315/http://www.vzglyad.ru/opinions/2013/11/22/660828.html|url-status=dead}}</ref>

In a poll of experts at the Global Catastrophic Risk Conference in Oxford (17–20 July 2008), the [[Future of Humanity Institute]] estimated the probability of complete human extinction by nuclear weapons at 1% within the century, the probability of 1 billion dead at 10% and the probability of 1 million dead at 30%.<ref>{{cite web|url=http://www.global-catastrophic-risks.com/docs/2008-1.pdf|title=Global Catastrophic Risks Survey|last2=Bostrom|first2=Nick|website=Future of Humanity Institute|publisher=Future of Humanity Institute, Oxford University|last1=Sandberg|first1=Anders|access-date=18 August 2016|archive-date=20 October 2016|archive-url=https://web.archive.org/web/20161020075724/http://www.global-catastrophic-risks.com/docs/2008-1.pdf|url-status=dead}}</ref> These results reflect the median opinions of a group of experts, rather than a probabilistic model; the actual values may be much lower or higher.

Scientists have argued that even a small-scale nuclear war between two countries, such as India and Pakistan, could have devastating global consequences and such local conflicts are more likely than full-scale nuclear war.<ref name="RobockRegional2007">{{cite journal|last1=Robock|first1=A|last2=Oman|first2=L|last3=Stenchikov|first3=GL|last4=Toon|first4=OB|last5=Bardeen|first5=C|last6=Turco|first6=RP|title=Climatic consequences of regional nuclear conflicts|journal=Atmos. Chem. Phys.|date=2007|volume=7|issue=8|pages=2003–2012|doi=10.5194/acp-7-2003-2007|bibcode=2007ACP.....7.2003R|url=https://hal.archives-ouvertes.fr/hal-00296198/file/acp-7-2003-2007.pdf|doi-access=free}}</ref><ref name="ToonandRobock2010">{{cite journal|last1=Robock|first1=A|last2=Toon|first2=OB|title=Local nuclear war, global suffering|journal=Scientific American|date=2010|volume=302|issue=1|pages=74–81|url=http://academic.evergreen.edu/z/zita/articles/SciAm/GW_CC/NuclearWar2010.pdf|access-date=13 February 2016|doi=10.1038/scientificamerican0110-74|doi-broken-date=2024-04-04|pmid=20063639|bibcode=2010SciAm.302a..74R|archive-date=15 December 2017|archive-url=https://web.archive.org/web/20171215060319/http://academic.evergreen.edu/z/zita/articles/SciAm/GW_CC/NuclearWar2010.pdf|url-status=dead}}</ref><ref name="NatureFood2022">{{cite journal |title=Global food insecurity and famine from reduced crop, marine fishery and livestock production due to climate disruption from nuclear war soot injection |journal=[[Nature Food]] |date=15 August 2022 |doi=10.1038/s43016-022-00573-0 |last1=Xia |first1=Lili |last2=Robock |first2=Alan |last3=Scherrer |first3=Kim |last4=Harrison |first4=Cheryl S. |last5=Bodirsky |first5=Benjamin Leon |last6=Weindl |first6=Isabelle |last7=Jägermeyr |first7=Jonas |last8=Bardeen |first8=Charles G. |last9=Toon |first9=Owen B. |last10=Heneghan |first10=Ryan |volume=3 |issue=8 |pages=586–596 |pmid=37118594 |s2cid=251601831 |doi-access=free |hdl=11250/3039288 |hdl-access=free }}</ref>

==Moral importance of human extinction risk==
{{Main|Human extinction#Ethics}}

In his book ''[[Reasons and Persons]]'', philosopher [[Derek Parfit]] posed the following question:<ref>{{cite book |title=Reasons and Persons |first=Derek |last=Parfit |author-link=Derek Parfit |publisher=[[Oxford University Press]] |year=1986 |chapter=154. How both human history, and the history of ethics, maybe just beginning|title-link=Reasons and Persons }}</ref>
<blockquote>Compare three outcomes:
#Peace.
#A nuclear war that kills 99% of the world's existing population.
#A nuclear war that kills 100%.
(2) would be worse than (1), and (3) would be worse than (2). Which is the greater of these two differences?</blockquote>
He continues that "Most people believe that the greater difference is between (1) and (2). I believe that the difference between (2) and (3) is ''very much'' greater." Thus, he argues, even if it would be bad if massive numbers of humans died, human extinction would itself be much worse because it prevents the existence of all future generations. And given the magnitude of the calamity were the human race to become extinct, [[Nick Bostrom]] argues that there is an overwhelming moral imperative to reduce even small risks of [[human extinction]].<ref>{{cite journal |doi=10.1111/1758-5899.12002 |first=Nick |last=Bostrom |author-link=Nick Bostrom |title=Existential Risk Prevention as Global Priority |journal=[[Global Policy]] |volume=4 |issue=1 |year=2013 |pages=15–31 |url=http://www.existential-risk.org/concept.html}}</ref>

==Likelihood of complete human extinction==
{{See also|Cobalt bomb|Nuclear winter}}
[[File:US and USSR nuclear stockpiles.svg|thumb|The United States and [[Soviet Union]]/Russia nuclear stockpiles, in [[Historical nuclear weapons stockpiles and nuclear tests by country|total number of nuclear bombs/warheads in existence]] throughout the [[Cold War]] and post-Cold War era.]]
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 parts of the world would remain habitable.<ref name=tonn>{{cite journal |author=Tonn, Bruce |author2=MacGregor, Donald |name-list-style=amp |doi=10.1016/j.futures.2009.07.009 |title=A singular chain of events |journal=Futures |volume=41 |issue=10 |year=2009 |pages=706–714|s2cid=144553194 }}</ref> Technically the risk may not be zero, as the climatic effects of nuclear war are uncertain and could theoretically be larger than current models suggest, just as they could theoretically be smaller than current models suggest.<!--<ref name=bostrom2002/> "(i) For there to be an existential risk it suffices that we can't be sure that it wouldn't. (ii) The climatic effects of a large nuclear war are not well known (there is the possibility of a nuclear winter)" --> There could also be indirect risks, such as a societal collapse following nuclear war that can make humanity much more vulnerable to other existential threats.<ref name=bostrom2002>{{cite journal |author=Bostrom, Nick |title=Existential risks |journal=Journal of Evolution and Technology |volume=9 |issue=1 |year=2002 |pages=1–31, §4.2 |url=http://www.nickbostrom.com/existential/risks.html}}</ref>

A related area of inquiry is: if a future nuclear arms race someday leads to larger stockpiles or more dangerous nuclear weapons than existed at the height of the Cold War, at what point could war with such weapons result in human extinction?<ref name=bostrom2002/> Physicist [[Leo Szilard]] warned in the 1950s that a deliberate [[doomsday device]] could be constructed by surrounding powerful hydrogen bombs with a massive amount of cobalt. Cobalt has a half-life of five years, and its global fallout might, some physicists have posited, be able to clear out all human life via lethal radiation intensity. The main motivation for building a cobalt bomb in this scenario is its reduced expense compared with the arsenals possessed by superpowers; such a doomsday device does not need to be launched before detonation and thus does not require expensive missile delivery systems, and the hydrogen bombs do not need to be miniaturized for delivery via missile. The system for triggering it might have to be completely automated, in order for the deterrent to be effective. A modern twist might be to also lace the bombs with aerosols designed to exacerbate nuclear winter. A major caveat is that nuclear fallout transfer between the northern and southern hemispheres is expected to be small; unless a bomb detonates in each hemisphere, the effect of a bomb detonated in one hemisphere on the other is diminished.<ref>{{cite book|author1=Max Tegmark|author-link=Max Tegmark|title=Life 3.0: Being Human in the Age of Artificial Intelligence|date=2017|publisher=Knopf|location=Doomsday Devices|isbn=9780451485076|edition=1st|chapter=Chapter 5: Aftermath: The Next 10,000 Years|title-link=Life 3.0: Being Human in the Age of Artificial Intelligence}}</ref>
{{further|Human extinction#Probability}}

== Effects of nuclear war ==
{{Pollution sidebar|War|image=[[File:Castle Bravo 007.jpg|frameless]]}} 
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 disruption. In a 1979 report for the U.S. Senate, the [[Office of Technology Assessment]] estimated casualties under different scenarios. For a full-scale [[countervalue]]/[[counterforce]] nuclear exchange between the U.S. and the Soviet Union, they predicted U.S. deaths from 35 to 77 percent (70 million to 160 million dead at the time), and Soviet deaths from 20 to 40 percent of the population.<ref name="Report1979">{{cite book|last1=Johns|first1=Lionel S|last2=Sharfman|first2=Peter|last3=Medalia|first3=Jonathan|last4=Vining|first4=Robert W|last5=Lewis|first5=Kevin|last6=Proctor|first6=Gloria|title=The Effects of Nuclear War|url=https://www.princeton.edu/~ota/disk3/1979/7906/7906.PDF|publisher=Library of Congress|access-date=13 February 2016|date=1979}}</ref>

Although this report was made when nuclear stockpiles were at much higher levels than they are today, it also was made before the risk of nuclear winter was first theorized in the early 1980s. Additionally, it did not consider other secondary effects, such as electromagnetic pulses (EMP), and the ramifications they would have on modern technology and industry.

=== Nuclear winter ===
{{Main|Nuclear winter}}
In the early 1980s, scientists began to consider the effects of smoke and soot arising from burning wood, plastics, and petroleum fuels in nuclear-devastated cities. It was speculated that the intense heat would carry these particulates to extremely high altitudes where they could drift for weeks and block out all but a fraction of the sun's light.<ref name="Britannica">{{cite web|title=Nuclear winter|url=https://www.britannica.com/topic/nuclear-winter|website=Encyclopædia Britannica|access-date=13 February 2016}}</ref> A landmark 1983 study by the so-called TTAPS team ([[Richard P. Turco]], [[Owen Toon]], Thomas P. Ackerman, [[James B. Pollack]] and [[Carl Sagan]]) was the first to model these effects and coined the term "nuclear winter."<ref>{{cite journal |title=Nuclear Winter: Global Consequences of Multiple Nuclear Explosions |journal=Science |volume=222 |issue=4630 |pages=1283–92 |date=23 December 1983 |pmid=17773320 |doi=10.1126/science.222.4630.1283|bibcode = 1983Sci...222.1283T |last1=Turco |first1=R. P. |last2=Toon |first2=O. B. |last3=Ackerman |first3=T. P. |last4=Pollack |first4=J. B. |last5=Sagan |first5=C. |s2cid=45515251 }}</ref>

More recent studies make use of modern global circulation models and far greater computer power than was available for the 1980s studies. A 2007 study examined the consequences of a global nuclear war involving moderate to large portions of the current global arsenal.<ref name="Robock2007">{{cite journal|last1=Robock|first1=Alan|last2=Oman|first2=Luke|last3=Stenchikov|first3=Georgiy L.|title=Nuclear winter revisited with a modern climate model and current nuclear arsenals: Still catastrophic consequences|journal=Journal of Geophysical Research|date=2007|volume=112|issue=D13107|page=14|doi=10.1029/2006JD008235|url=http://climate.envsci.rutgers.edu/pdf/RobockNW2006JD008235.pdf|access-date=13 February 2016|bibcode=2007JGRD..11213107R|doi-access=free}}</ref> The study found cooling by about 12–20&nbsp;°C in much of the core farming regions of the US, Europe, Russia and China and as much as 35&nbsp;°C in parts of Russia for the first two summer growing seasons. The changes they found were also much longer-lasting than previously thought, because their new model better represented entry of soot aerosols in the upper stratosphere, where precipitation does not occur, and therefore clearance was on the order of 10 years.<ref name="ToonandRobock2010" /> In addition, they found that global cooling caused a weakening of the global hydrological cycle, reducing global [[Precipitation (meteorology)|precipitation]] by about 45%.

The authors did not discuss the implications for agriculture in depth, but noted that a 1986 study which assumed no food production for a year projected that "most of the people on the planet would run out of food and starve to death by then" and commented that their own results show that, "This period of no food production needs to be extended by many years, making the impacts of nuclear winter even worse than previously thought."<ref name="Robock2007" />

In contrast to the above investigations of global nuclear conflicts, studies have shown that even small-scale, regional nuclear conflicts could disrupt the global climate for a decade or more. In a regional nuclear conflict scenario where two opposing nations in the [[subtropics]] would each use 50 [[Atomic bombings of Hiroshima and Nagasaki|Hiroshima]]-sized nuclear weapons (about 15 kilotons each) on major populated centres, the researchers estimated as much as five million tons of soot would be released, which would produce a cooling of several degrees over large areas of [[North America]] and [[Eurasia]], including most of the grain-growing regions.<ref name="ScienceDaily">[https://www.sciencedaily.com/releases/2006/12/061211090729.htm Regional Nuclear War Could Devastate Global Climate], Science Daily, December 11, 2006</ref><ref name="RobockRegional2007"/><ref name="ToonandRobock2010"/> The cooling would last for years, and according to the research, could be "catastrophic". Additionally, the analysis showed a 10% drop in average global precipitation, with the largest losses in the low latitudes due to failure of the monsoons.

Regional nuclear conflicts could also inflict significant damage to the ozone layer. A 2008 study found that a regional nuclear weapons exchange could create a near-global ozone hole, triggering human health problems and impacting agriculture for at least a decade.<ref name=Mills2008>{{cite journal |title=Massive global ozone loss predicted following regional nuclear conflict |journal=Proc. Natl. Acad. Sci. U.S.A. |date=2008 |pmid=18391218 |pmc=2291128 |doi=10.1073/pnas.0710058105 |last1=Mills |first1=M. J. |last2=Toon |first2=O. B. |last3=Turco |first3=R. P. |last4=Kinnison |first4=D. E. |last5=Garcia |first5=R. R. |volume=105 |issue=14 |pages=5307–12 |bibcode = 2008PNAS..105.5307M |doi-access=free }}[http://acd.ucar.edu/~mmills/pdf/2008MillsPNAS_MassiveOzoneLoss.pdf as PDF] {{webarchive|url=https://web.archive.org/web/20160304100404/http://acd.ucar.edu/~mmills/pdf/2008MillsPNAS_MassiveOzoneLoss.pdf |date=2016-03-04 }}</ref> This effect on the ozone would result from heat absorption by soot in the upper stratosphere, which would modify wind currents and draw in ozone-destroying nitrogen oxides. These high temperatures and nitrogen oxides would reduce ozone to the same dangerous levels that are experienced below the ozone hole above Antarctica every spring.<ref name="ToonandRobock2010"/>

=== Nuclear famine ===
{{Main|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.<ref>Harwell, M., and C. Harwell. (1986). "Nuclear Famine: The Indirect Effects of Nuclear War", pp. 117–135 in Solomon, F. and R. Marston (Eds.). ''The Medical Implications of Nuclear War''. Washington, D.C.: National Academy Press. {{ISBN|0309036925}}.</ref> In 2013 and 2022 reports, the [[International Physicians for the Prevention of Nuclear War]] (IPPNW) voiced concerns that more than two billion people, about a third of the world's population, would be at risk of starvation in the event of a regional nuclear exchange between India and Pakistan, or by the use of even a small proportion of nuclear arms held by America and Russia.<ref name="IPPNWreport2013">{{cite web|last1=Helfand|first1=Ira|title=Nuclear Famine: Two Billion Prople at Risk?|url=https://www.ippnw.org/wp-content/uploads/2020/07/2013-Nuclear-Famine.pdf|website=IPPNW|access-date=30 December 2022}}</ref><ref name="IPPNWreport2022">{{cite web|last1=Bivens|first1=Matt|title=Nuclear Famine: Even a "limited" nuclear war would cause abrupt climate disruption and global starvation|url=https://www.ippnw.org/wp-content/uploads/2022/09/ENGLISH-Nuclear-Famine-Report-Final-bleed-marks.pdf|website=IPPNW|access-date=30 December 2022}}</ref> Several independent studies{{Citation needed|date=December 2020}} show corroborated conclusions that agricultural outputs would be significantly reduced for years by climatic changes driven by nuclear wars. Reduction of food supply would be further exacerbated by rising [[food prices]], affecting hundreds of millions of vulnerable people, especially in the poorest nations of the world.

According to a peer-reviewed study published in the journal ''[[Nature Food]]'' in August 2022,<ref name="NatureFood2022"></ref> a full-scale nuclear war between the U.S. and Russia might kill 360 million people directly and more than 5 billion people might die as a consequence from [[starvation]] due to soot created by firestorms after nuclear bombing. More than 2 billion people were projected to die as a consequence from a smaller-scale nuclear war between India and Pakistan. In the event of a nuclear war between Russia and the United States, 99% of the people in the United States, Russia, Europe, and China would die.<ref>{{cite magazine |title=Here's How Bad a Nuclear War Would Actually Be |url=https://time.com/6290977/nuclear-war-impact-essay/ |magazine=Time |date=29 June 2023}}</ref>

=== Electromagnetic pulse ===
{{See also|Nuclear electromagnetic pulse|High-altitude nuclear explosion}}

An [[electromagnetic pulse]] (EMP) is a burst of electromagnetic radiation. Nuclear explosions create a pulse of electromagnetic radiation called a nuclear EMP or NEMP. Such EMP interference is known to be generally disruptive or damaging to electronic equipment.<ref name="science">Broad, William J. "Nuclear Pulse (I): Awakening to the Chaos Factor", ''Science''. 29 May 1981 212: 1009–1012</ref>

By disabling electronics and their functioning, an EMP would disable hospitals, water treatment facilities, food storage facilities, and all electronic forms of communication, and thereby threaten key aspects of the modern human condition.{{citation needed|date=November 2016}} Certain EMP attacks could lead to a large loss of power for months or years.<ref name="EMP report">{{cite web|title=Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack|url=http://commdocs.house.gov/committees/security/has204000.000/has204000_0.HTM|access-date=16 January 2016}}</ref> Currently, failures of the power grid are dealt with using support from the outside. In the event of an EMP attack, such support would not exist and all damaged components, devices, and electronics would need to be completely replaced.

In 2013, the US House of Representatives considered the "Secure High-voltage Infrastructure for Electricity from Lethal Damage Act" that would provide surge protection for some 300 large transformers around the country.<ref>{{cite web |last1=McCormack|first1=John |title=Lights out: House plan would protect nation's electricity from solar flare, nuclear bomb |date=2013-06-17 |url=http://www.washingtonexaminer.com/lights-out-house-plan-would-protect-nations-electricity-from-solar-flare-nuclear-bomb/article/2532038 |website=[[Washington Examiner]] |access-date=2016-01-16}}</ref> The problem of protecting civilian infrastructure from electromagnetic pulse has also been intensively studied throughout the European Union, and in particular by the United Kingdom.<ref>House of Commons
Defence Committee, [https://publications.parliament.uk/pa/cm201012/cmselect/cmdfence/1552/1552.pdf "Developing Threats: Electro-Magnetic Pulses (EMP)"]. Tenth Report of Session 2010–12.</ref> While precautions have been taken, James Woolsey and the EMP Commission suggested that an EMP is the most significant threat to the U.S.<ref name="EMP report"/><ref>{{cite news |last1=Woosley|first1=R. James |last2=Pry|first2=Peter Vincent |title=The Growing Threat From an EMP Attack |date=2014-08-12 |url=https://www.wsj.com/articles/james-woolsey-and-peter-vincent-pry-the-growing-threat-from-an-emp-attack-1407885281 |newspaper=[[Wall Street Journal]] |access-date=2016-01-16 |url-access=subscription }}</ref>

The risk of an EMP, either through solar or atmospheric activity or enemy attack, while not dismissed, was suggested to be overblown by the news media in a commentary in ''[[Physics Today]]''.<ref name="PT2016">{{cite journal |first1=Steven T. |last1=Corneliussen |title=Conservative media sustain alarm about a possible electromagnetic-pulse catastrophe |date=2016-06-23 |doi=10.1063/PT.5.8178 |journal=[[Physics Today]] }}</ref> Instead, the weapons from rogue states were still too small and uncoordinated to cause a massive EMP, underground infrastructure is sufficiently protected, and there will be enough warning time from continuous solar observatories like [[Solar and Heliospheric Observatory|SOHO]] to protect surface transformers should a devastating solar storm be detected.<ref name="PT2016"/>

=== Nuclear fallout ===
{{Main|Nuclear fallout}}

Nuclear fallout is the residual radioactive dust and ash propelled into the upper atmosphere following a nuclear explosion.<ref>{{cite web|url=http://www.atomicarchive.com/Effects/effects17.shtml|title=Radioactive Fallout {{!}} Effects of Nuclear Weapons {{!}} atomicarchive.com|website=www.atomicarchive.com|access-date=2016-12-31}}</ref> Fallout is usually limited to the immediate area, and can only spread for hundreds of kilometers from the explosion site if the explosion is high enough in the atmosphere. Fallout may get [[Entrainment (meteorology)|entrained]] with the products of a [[pyrocumulus]] cloud and fall as black rain<ref>{{cite web|url=http://atomicbombmuseum.org/3_radioactivity.shtml|title=AtomicBombMuseum.org – Destructive Effects|website=atomicbombmuseum.org|access-date=2016-12-31}}</ref> (rain darkened by soot and other particulates).

This radioactive dust, usually consisting of [[fission product]]s mixed with bystanding atoms that are [[neutron activation|neutron activated by exposure]], is a highly dangerous kind of [[radioactive contamination]]. The main radiation hazard from fallout is due to short-lived radionuclides external to the body.<ref name="AtomicArchive">{{cite web|title=Radioactive Fallout|url=http://www.atomicarchive.com/Effects/effects17.shtml|website=Atomic Archive|access-date=23 January 2016}}</ref> While most of the particles carried by nuclear fallout decay rapidly, some radioactive particles will have half-lives of seconds to a few months. Some radioactive isotopes, like [[strontium-90]] and [[caesium-137]], are very long-lived and will create radioactive hot spots for up to 5 years after the initial explosion.<ref name="AtomicArchive"/> Fallout and black rain may contaminate waterways, agriculture, and soil. Contact with radioactive materials can lead to radiation poisoning through external exposure or accidental consumption. In acute doses over a short amount of time radiation will lead to prodromal syndrome, bone marrow death, central nervous system death and gastrointestinal death.<ref name = "Coggle & Lindop">Coggle, J.E., Lindop, Patricia J. "Medical Consequences of Radiation Following a Global Nuclear War." The Aftermath (1983): 60–71.</ref> Over longer periods of exposure to radiation, cancer becomes the main health risk. Long-term radiation exposure can also lead to in utero effects on human development and transgenerational genetic damage.<ref name = "Coggle & Lindop"/><ref>{{cite web|url=http://www.rerf.jp/radefx/genetics_e/birthdef.html|title=公益財団法人 放射線影響研究所 RERF|website=www.rerf.jp|access-date=16 November 2018}}</ref>

==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 (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 only the "cockroaches would survive" is critically dealt with in the 1988 book ''[[Philip J. Dolan#Unclassified publications|Would the Insects Inherit the Earth and Other Subjects of Concern to Those Who Worry About Nuclear War]]'', by nuclear weapons expert [[Philip J. Dolan]].

In 1982, [[nuclear disarmament]] activist [[Jonathan Schell]] published ''[[The Fate of the Earth]]'', which is regarded by many to be the first carefully argued presentation that concluded that extinction is a significant possibility from nuclear war. However, the assumptions made in this book have been thoroughly analyzed and determined to be "quite dubious".<ref name="The fate of extinction arguments">{{cite web |url=http://www.bmartin.cc/pubs/83fea.html |title=The fate of extinction arguments|date=March 1983|author=Martin, Brian|publisher=Department of Mathematics, Faculty of Science, Australian National University }}</ref> The impetus for Schell's work, according to physicist Brian Martin, was:

<blockquote> The implicit premise [...] that if people are not taking action on the issue, they must not perceive it as threatening enough. Perhaps if the thought of 500 million people dying in a nuclear war is not enough to stimulate action, then the thought of extinction will. Indeed, Schell explicitly advocates use of the fear of extinction as the basis for inspiring the "complete rearrangement of world politics" (p. 221)<ref name="The fate of extinction arguments" /></blockquote>

The belief in "overkill" is also commonly encountered, with an example being the following statement made by nuclear disarmament activist [[Philip Noel-Baker]] in 1971: "Both the US and the Soviet Union now possess nuclear stockpiles large enough to exterminate mankind three or four – some say ten – times over". Brian Martin suggested that the origin of this belief was from "crude linear extrapolations" of the bombing of Hiroshima. He said that if the bomb dropped on Hiroshima had been 1,000 times as powerful, it could not have killed 1,000 times as many people.<ref name="ReferenceB"/> Similarly, it is common to see stated that the combined explosive energy released in the entirety of [[World War II]] was about 3 megatons, while a nuclear war with warhead stockpiles at Cold War highs would release 6000 WWII's of explosive energy.<ref>{{cite journal|author=Willens, Harold|author-link=Harold Willens|url=http://c-g-i.info/images/nuclear-weapons-chart.jpg |title=The Trimtab factor, 1984 |year=1990 |journal=Alternatives |volume=16|issue=4}}</ref> An estimate for the necessary amount of fallout to begin to have the potential of causing human extinction is regarded by physicist and disarmament activist [[Joseph Rotblat]] to be 10 to 100 times the megatonnage in nuclear arsenals as they stood in 1976; however, with the world megatonnage decreasing since the Cold War ended this possibility remains hypothetical.<ref name="ReferenceB"/>
[[File:NuclearTestUS.gif|thumb|300px|The massive use and deployment of nuclear weapons are commonly theorized to yield enough global destructive potential to render large parts of the Earth uninhabitable.]]
According to the 1980 [[United Nations]] report ''General and Complete Disarmament: Comprehensive Study on Nuclear Weapons: Report of the Secretary-General'', it was estimated that there were a total of about 40,000 [[Historical nuclear weapons stockpiles and nuclear tests by country|nuclear warheads in existence]] at that time, with a potential combined explosive yield of approximately 13,000 [[TNT equivalent|megatons]].

By comparison – in the [[timeline of volcanism on Earth]] – the [[1815 eruption of Mount Tambora|1815 eruption]] of [[Mount Tambora]] exploded with a force of roughly 30,000 megatons,<ref>{{Cite journal|date=1986-01-01|title=The petrology of Tambora volcano, Indonesia: A model for the 1815 eruption|url=https://www.sciencedirect.com/science/article/abs/pii/037702738690079X|journal=Journal of Volcanology and Geothermal Research|language=en|volume=27|issue=1–2|pages=1–41|doi=10.1016/0377-0273(86)90079-X|issn=0377-0273|last1=Foden|first1=J.|bibcode=1986JVGR...27....1F}}</ref> and ejected {{convert|160|km3|cumi|abbr=on}} of mostly rock and [[tephra]],<ref name="Stothers1984">
{{cite journal | last = Stothers | first = Richard B. | journal = [[Science (journal)|Science]] | title = The Great Tambora Eruption in 1815 and Its Aftermath | volume = 224 | issue = 4654 | date = 1984 | pages = 1191–1198 | doi = 10.1126/science.224.4654.1191 | pmid = 17819476
|bibcode = 1984Sci...224.1191S | s2cid = 23649251 }}
</ref> which included 120 million [[tonne]]s of sulfur dioxide as [[Mount Tambora#Global effects|an upper estimate]], turning 1816 into the "[[Year Without a Summer|year without a summer]]" due to the levels of [[global dimming]] [[sulfate]] aerosols and ash expelled.<ref name="Oppenheimer2003">
{{cite journal | last = Oppenheimer | first = Clive | title = Climatic, environmental and human consequences of the largest known historic eruption: Tambora volcano (Indonesia) 1815 | journal = Progress in Physical Geography | volume = 27 | issue = 2 | date = 2003 | pages = 230–259 | doi = 10.1191/0309133303pp379ra
| bibcode = 2003PrPG...27..230O | s2cid = 131663534 }}
</ref> The larger [[Lake Toba#Major eruption|Mount Toba eruption]], which occurred approximately 74,000 years ago, produced an estimated {{convert|2800|km3|abbr=on}} of tephra<ref name=USGS>{{cite web |url= http://hvo.wr.usgs.gov/volcanowatch/2005/05_04_28.html |title=Supersized eruptions are all the rage! |date=April 28, 2005 |publisher=[[United States Geological Survey|USGS]]}}</ref> and {{convert|6000|e6t|ST}} of sulfur dioxide,<ref name=robock2009>{{cite journal
 | author1=Robock, A.|author2=C.M. Ammann|author3=L. Oman|author4=D. Shindell|author5=S. Levis|author6=G. Stenchikov
 | title=Did the Toba volcanic eruption of ~74k BP produce widespread glaciation?
 | journal=[[Journal of Geophysical Research]] | date=2009 | volume=114 |issue=D10| pages= D10107
 | doi=10.1029/2008JD011652
| bibcode=2009JGRD..11410107R
| doi-access=free}}</ref><ref>{{cite journal 
 | last1 = Huang | first1 = C.Y.
 | last2 = Zhao | first2 = M.X.
 | last3 = Wang | first3 = C.C.
 | last4 = Wei | first4 = G.J.
 | title = Cooling of the South China Sea by the Toba Eruption and correlation with other climate proxies ~71,000 years ago
 | journal = Geophysical Research Letters | date = 2001 | volume = 28 | issue = 20 | pages = 3915–3918
 | doi = 10.1029/2000GL006113 | bibcode=2001GeoRL..28.3915H
| doi-access = free }}</ref> with a possible explosion force of 20,000,000 megatons (Mt) of TNT, forming [[Lake Toba]] and reducing the human population to mere tens of thousands. The [[Chicxulub impact]], connected with the [[extinction of the dinosaurs]], corresponds to at least 70,000,000&nbsp;Mt of energy, which is roughly 7000 times the combined maximum arsenal of the US and Soviet Union.

Comparisons with [[supervolcanos]] are more misleading than helpful due to the different [[aerosol]]s released, the likely [[air burst]] fuzing height of nuclear weapons and the globally scattered location of these potential nuclear detonations all being in contrast to the singular and subterranean nature of a supervolcanic eruption.<ref name="ReferenceA">[[Lynn Margulis|Margulis, Lynn]] (1999). ''Symbiotic Planet: A New Look At Evolution''. Houston: Basic Book.</ref> Moreover, assuming the entire world stockpile of weapons were grouped together, it would be difficult due to the [[nuclear fratricide]] effect to ensure the individual weapons would detonate all at once. Nonetheless, many people believe that a full-scale nuclear war would result, through the nuclear winter effect, in the [[human extinction|extinction of the human species]], though not all analysts agree on the assumptions put into these nuclear winter models.<ref name="bmartin.cc"/>

==See also==
* {{annotated link|Second Cold War}}
* {{annotated link|Environmental impact of war}}
* {{annotated link|Global catastrophic risk}}
* {{annotated link|Human extinction}}
* {{annotated link|List of nuclear holocaust fiction}}
* {{annotated link|Nuclear anxiety}}
* {{annotated link|Nuclear terrorism}}
* {{annotated link|Silurian hypothesis}}
* {{annotated link|World War III}}

==References==
{{Reflist|30em}}

==External links==
* [http://www.wsu.edu/~brians/nuclear/index.htm Nuclear Holocausts: Atomic War in Fiction, By Paul Brians, Professor of English, Washington State University, Pullman, Washington]
* [http://www.overcomingbias.com/2012/11/nuclear-winter-and-human-extinction-qa-with-luke-oman.html Brief Q&A] with [[Luke Oman]] on the unlikeliness of human extinction from nuclear war

{{Doomsday}}
{{Pollution}}

[[Category:Nuclear doomsday]]
[[Category:Human extinction]]