page_title: Nuclear winter
section_title: Policy implications
hierarchical_section_title: Nuclear winter / Policy implications
caption_attribution_description: English: The Buster-Jangle Uncle nuclear test.
context_page_description: Nuclear winter is a severe and prolonged global climatic cooling effect hypothesized to occur after widespread firestorms following a nuclear war. The hypothesis is based on the fact that such fires can inject soot into the stratosphere, where it can block some direct sunlight from reaching the surface of the Earth. It is speculated that the resulting cooling would lead to widespread crop failure and famine. When developing computer models of nuclear-winter scenarios, researchers use the conventional bombing of Hamburg, and the Hiroshima firestorm in World War II as example cases where soot might have been injected into the stratosphere, alongside modern observations of natural, large-area wildfire-firestorms.
context_section_description: During the Cuban Missile Crisis, Fidel Castro and Che Guevara called on the USSR to launch a nuclear first strike against the US in the event of a US invasion of Cuba. In the 1980s Castro was pressuring the Kremlin to adopt a harder line against the US under President Ronald Reagan, even arguing for the potential use of nuclear weapons. As a direct result of this a Soviet official was dispatched to Cuba in 1985 with an entourage of "experts", who detailed the ecological effect on Cuba in the event of nuclear strikes on the United States. Soon after, the Soviet official recounts, Castro lost his prior "nuclear fever". In 2010 Alan Robock was summoned to Cuba to help Castro promote his new view that nuclear war would bring about Armageddon. Robock's 90 minute lecture was later aired on the nationwide state-controlled television station in the country.
  However, according to Robock, insofar as getting US government attention and affecting nuclear policy, he has failed. In 2009, together with Owen Toon, he gave a talk to the United States Congress but nothing transpired from it and the then presidential science adviser, John Holdren, did not respond to their requests in 2009 or at the time of writing in 2011.
  In a 2012 "Bulletin of the Atomic Scientists" feature, Robock and Toon, who had routinely mixed their disarmament advocacy into the conclusions of their "nuclear winter" papers, argue in the political realm that the hypothetical effects of nuclear winter necessitates that the doctrine they assume is active in Russia and US, "mutually assured destruction" (MAD) should instead be replaced with their own "self-assured destruction" (SAD) concept, because, regardless of whose cities burned, the effects of the resultant nuclear winter that they advocate, would be, in their view, catastrophic. In a similar vein, in 1989 Carl Sagan and Richard Turco wrote a policy implications paper that appeared in AMBIO that suggested that as nuclear winter is a "well-established prospect", both superpowers should jointly reduce their nuclear arsenals to "Canonical Deterrent Force" levels of 100–300 individual warheads each, such that in "the event of nuclear war [this] would minimize the likelihood of [extreme] nuclear winter."
  
  An originally classified 1984 US interagency intelligence assessment states that in both the preceding 1970s and 80s, the Soviet and US military were already following the "existing trends" in warhead miniaturization, of higher accuracy and lower yield nuclear warheads, this is seen when assessing the most numerous physics packages in the US arsenal, which in the 1960s were the B28 and W31, however both quickly became less prominent with the 1970s mass production runs of the 50 Kt W68, the 100 Kt W76 and in the 1980s, with the B61. This trend towards miniaturization, enabled by advances in inertial guidance and accurate GPS navigation etc., was motivated by a multitude of factors, namely the desire to leverage the physics of equivalent megatonnage that miniaturization offered; of freeing up space to fit more MIRV warheads and decoys on each missile. Alongside the desire to still destroy hardened targets but while reducing the severity of fallout collateral damage depositing on neighboring, and potentially friendly, countries. As it relates to the likelihood of nuclear winter, the range of potential thermal radiation ignited fires was already reduced with miniaturization. For example, the most popular nuclear winter paper, the 1983 TTAPS paper, had described a 3000 Mt counterforce attack on ICBM sites with each individual warhead having approximately one Mt of energy; however not long after publication, Michael Altfeld of Michigan State University and political scientist Stephen Cimbala of Pennsylvania State University argued that the then already developed and deployed smaller, more accurate warheads (e.g. W76), together with lower detonation heights, could produce the same counterforce strike with a total of only 3 Mt of energy being expended. They continue that,  if the nuclear winter models prove to be representati
caption: The 1951 Shot Uncle of Operation Buster-Jangle, had a yield about a tenth of the 13 to 16 Kt Hiroshima bomb, 1.2 Kt,[195] and was detonated 5.2 m (17 ft) beneath ground level.[196] No thermal flash of heat energy was emitted to the surroundings in this shallow buried test.[195] The explosion resulted in a cloud that rose to 3.5 km (11,500 ft).[197] The resulting crater was 260 feet wide and 53 feet deep.[198] The yield is similar to that of an Atomic Demolition Munition. Altfeld and Cimbala argue that true belief in nuclear winter might lead nations towards building greater arsenals of weapons of this type.[199] However, despite being complicated due to the advent of Dial-a-yield technology, data on these low yield nuclear weapons suggests that they, as of 2012, make up about a tenth of the arsenal of the US and Russia, and the fraction of the stockpile that they occupy has diminished since the 1970-90s, not grown.[200] A factor in this is that very thin devices with yields approximately around 1 kiloton of energy are nuclear weapons that make very inefficient use of their nuclear materials, e.g. two-point implosion. Thus a more psychologically detering higher efficiency/higher yield device, can instead be constructed from the same mass of fissile material.
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