It is a question that the world keeps asking itself more or less since the end of the World War II: the atomic bombs dropped in Hiroshima and Nagasaki in 1945 gave clear evidence of the serious consequences of the use of nuclear devices inside any armed conflict, and this general awareness gave birth to the Cold War between the United States and Russia. A war based precisely on the concept of nuclear deterrence, i.e. on the awareness that if one of the two parties started to use of atomic bombs, the power of the two arsenals is such that the automatic response would seriously jeopardize the existence of humanity on planet Earth.
Since then, in reality, the atomic threat has never ceased to exist. Although years of attempts of nuclear disarmament have passed (the world nuclear endowment was reduced, but it’s still there), and although the tensions between the United States and Russia have gradually subsided (at least until some time ago), the moments in which the nuclear risk was real were not lacking. Only in recent times we had North Korea’s demonstrations of power of past years, and the war between India and Pakistan that provides continue warnings. And given that we always have many wars active in the world at any given time, we have to ask ourselves how the use of large-scale nuclear bombs could change the world in which we live.
So the question is: what does really humanity risk in the event of nuclear war?
There have been several studies on the subject in recent times. Most are well summarized by this Wikipedia article, next to which this article by Vox from a few years ago makes a good impression. The launch of nuclear missiles would have local and global effects, and they are all the more serious the higher the number of bombs dropped.
Nuclear technology has advanced considerably since the days of Hiroshima and Nagasaki, so it is obvious to imagine that the effects of a nuclear bomb today would be far worse than what they were then. The use of a medium-large sized atomic bomb would create an explosion with immediate effects in an area with a diameter of 15-30 kilometers. In the closest area to the mushroom cloud that would be generated, the immediate mortality would be 90%. The impact would be such that the buildings would collapse even if placed about ten kilometers from the collision, whereas for at least another ten kilometers there would be injuries due to broken glass and other secondary effects.
This is only with regard to the effects of the explosion. To these are added the effects of radioactivity, which can lead to death both within a few hours (due to high radioactivity) and in a few weeks (with lower radioactivity). And obviously the whole area would be contaminated, preventing the growth of edible vegetation and causing an enormous economic damage.
It is estimated that if a medium-sized atomic bomb were dropped in a densely populated area, such as Washington today, it would cause the immediate death of over 200,000 people. More than what the Hiroshima and Nagasaki bombs did together.
The concern related to the use of nuclear weapons is that it would cause a response, and could lead to the explosion of multiple nukes in a short time. The effects of this would be enormous not only for the geographic area involved, but for the whole world. In particular, the greatest risk is that linked to the so-called “nuclear winter” (or “nuclear autumn” if we consider the intermediate version). It is estimated that the use of just 50 nuclear bombs between India and Pakistan would result in a nuclear autumn that would kill 30% of the world’s population in the years to come, while if Russia and the United States start a nuclear war and drop 2,000 bombs, the resulting nuclear winter would destroy almost all of humanity. Either way, the world as we would know it would cease to exist.
What is the nuclear winter? It is a set of direct climatic consequences due to the radioactive smoke generated by the explosion of atomic bombs. This smoke, in large quantities, would reach the stratosphere, block the sunlight for years and at the same time destroy the ozone layer that protects Earth. Blocking the sun’light would cause temperatures to drop by 10-13 degrees Celsius and reduce precipitation by 50%. The two events combined would kill almost all of humanity, due to the adverse climate and the famines due to the lack of food and water. Furthermore, even after the smoke cloud has dissolved, the absence of ozone would prevent most of the inhabitants of the Western world from going out outdoors, without the risk of immediate sunburns. In short, even if we survived, we would face a world far from being able to be enjoyed.
How likely is a nuclear war today?
Although many indicators tell us that we have never been closer to nuclear war than in recent years, it is wise to downsize the objective risks. All nations in possession of nuclear weapons are perfectly aware of the risks they run, and even the economic consequences would be unsustainable for anyone. And to this it must be added that the nuclear winter scenario described above is the most pessimistic of all, and not all scientists agree on that type of forecast.
Some scientists have tried to give numbers, and believe that the probability of humanity extinction in a nuclear war by the end of the century is less than 1%. While they estimate around 30% the probability that a million people could die in this century due to the use of atomic bombs.
The media often insist with particular vehemence on messages and news that inspire fear, because those generate a higher average attention than reassuring news. It is therefore up to us to filter the information that reaches us, aware that those that spread uncertainty are more cumbersome and worrying than neutral ones. Yes, the risk of nuclear war is not zero as long as nuclear weapons exist. But when we evaluate pessimistic scenarios, we need to be able to counterbalance the natural propension of the human mind to worry in advance about events that have a relatively low probability of occurring.