A recent study of the ecological consequences of a limited nuclear exchange involving the established nuclear weapon states concludes that it would take a relatively small number of nuclear detonations to trigger significant climatic impacts, and that upon a planetary scale.
Essentially, the study, by Liska, White, Holey and Oglesby, seeks to quantify the amount of soot emitted into the atmosphere from burning urban and industrial targets following a limited nuclear strike that employs weapons that characterise the strategic nuclear arsenals of the established nuclear weapon states.
A report on the study appears at PhysOrg, and the study itself can be read online without traversing a paywall. The study first reports on the conclusions of a well known paper on the climatic impact of a regional nuclear war involving India and Pakistan due to Toon, Robock et al i.e. some of the founders of the theory of nuclear winter
In previous regional nuclear war simulations, roughly 100 nuclear explosions with 15-KT (kilotons) TNT yields were estimated to ignite 1,300 square kilometers of urban and other developed land area.The resulting oxidation of carbonaceous materials (e.g., soils, biomass, fossil fuels, asphalt, plastics) was estimated to disperse >5 million metric tons (5 Tg C) of black carbon smoke particles into the stratosphere
The 100 nuclear explosions with 15KT weapons are on Indian and Pakistani cities. That represents a full scale countervalue nuclear war in South Asia.
According to Toon et al the results would be significant and spread beyond South Asia, as White et al report
As a consequence of 5 Tg of black carbon being lofted into the stratosphere, solar radiation on land, atmospheric surface temperature, and rainfall would decrease globally and would likely result in a dramatic decrease in global agricultural production. Agricultural growing seasons could be reduced by 10 to 40 days per year for at least 5 years; global temperatures could be below normal for as long as 25 years; and immediate short-term temperatures could be colder than have occurred in the last 1,000 years
The study at hand, i.e. White et al, is different because it assumes few, though high yield, weapons employed by the established nuclear weapon states, such as Russia and the US, against urban-industrial targets
The use of only one 5-MT land-based missile deployed by China could burn an area similar in size to that of one hundred 15-KT explosions. Alternatively, if the United States dropped only three 1.2-MT bombs, or used two Trident D5 SLBM (each with four 475-KT warheads), the size of the explosions would exceed the land area required to produce similar climate impacts. Use of only four 800-KT Russian ICBMs or ten 300-KT French gravity bombs would also have similar climate impacts. Thus, use of as few as 1 to 10 deployed nuclear weapons, and fewer than 25 of these prevalent types, from the five official nuclear weapons countries could produce a nuclear drought
Notice that the study claims that the global ecological consequences would be on a par with that reported by Toon et al for South Asia. That one 5MT nuclear weapon might one day be a North Korean one, I might add.
One thing we need to be mindful of is that many of the weapons the authors refer to have, or certainly can have, variable yields including low yields. It is unlikely that the use of a limited nuclear strike in a crisis, in order to signal resolve or seek termination of a crisis on terms favourable to the attacker, would involve small high yield attacks on an urban-industrial target.
But certainly, the escalatory process can rapidly head in such a direction.
Studies such as this, assuming that the conclusions reached are defensible, nuclear winter was and remains controversial in the scientific community, then we would have an empirical limitation on the rationality of intra-war deterrence. Limited nuclear exchanges or intra-war deterrence come to us via game theory or rational choice theory, and if this study is right then intra-war deterrence has little rational basis for the planetary scale effects of a limited strike has serious cost impacts upon the attacker.
The effect is to limit the extent of a limited attack to low yield weapons on non or small urban-industrial targets. The defender might regard anything beyond this as irrational, and thus highly unlikely so thereby lowering the credibility of any such use of nuclear weapons by an attacker in a bizarre type of nuclear communication. One wonders whether the efficiency of such communication, which is designed to send or signal to the defender information regarding the resolve of the attacker, could be quantitively analysed through use of Shannon’s theory of communication.
Speaking of Toon et al it would appear that the pioneers of nuclear winter are set upon a much more involved treatment of the problem, according to PhysOrg
Scientists and students led by the University of Colorado Boulder and Rutgers University are calculating the environmental and human impacts of a potential nuclear war using the most sophisticated scientific tools available…
… The new study will calculate in detail for the first time the impacts of nuclear war on agriculture and the oceanic food chain and on humans, including food availability and migration activity, said Toon of CU Boulder’s Laboratory for Atmospheric and Space Physics. The team is using various scenarios to calculate how much smoke produced by fires in modern cities initiated by nuclear blasts would be produced by urban firestorms and their available fuels, Toon said
An interesting feature of nuclear strategy is the way that planners do not take such considerations into account when formulating the damage expectancy criteria of nuclear strikes. They focus on blast or burst effects alone. This is a reflection of the dominance of counterforce strategies, at least in the United States. Lynne Eden published a magisterial study of this in her Whole World on Fire concluding that the singular concern for blast effects is reflective of a cognitive bias peculiar to the way knowledge is framed by nuclear planners.
Surely Eden is correct, but I wonder whether matters are more deeper than an institutional cognitive bias.
These studies on the ecological impacts of nuclear conflict remind us that ecological political thought had its origins in widespread concerns regarding the planetary impacts of nuclear conflict during the cold war. Hence Greenpeace.
Since the end of the cold war the ecological movement has tended to forget this, putting nuclear weapons and their possible ecological consequences to the side. Studies such as this might hopefully rekindle the ecological movement’s interest in nuclear weapons.