Note to readers: This is being reposted with minor additions for the benefit of new and free subscribers, and in support of the Physicists' Coalition for Nuclear Threat Reduction's upcoming Action Days on Capital Hill, where we will be urging lawmakers to renew efforts to reduce the risk of a nuclear war. If you agree that reducing the size of our nuclear weapons stockpiles is a good thing, please contact your senators and representative, especially during the week of April 16, 2024.
Just about everyone would agree that a war involving thermonuclear weapons would be a bad thing, and it has been known since the late 1950s that an all-out nuclear war between the US and the Soviet Union (or its prospective successor, the Russian Federation) would lead to hundreds of millions of deaths and incalculable damage. Since around 1980 it has been known that the results of such a war would be considerably worse, and the American public was awaken to that in 1983 with the publication of an article in the Sunday newspaper magazine Parade by Carl Sagan [2]. In it, Sagan explained the results of studies that indicated that an effect of such a war would be to inject a large mass of tiny soot particles into the stratosphere, blocking sunlight to such a degree as to cause severe cooling of the planet and a drastic reduction of plant biomass for years, leading to a global famine from which no large animals - humans included - would likely emerge. This nuclear winter effect has been studied over the ensuing years, using improved understanding of climatology and vastly more capable computing capabilities, with the not only the confirmation [3] of the original work but also extension of its applicability to smaller nuclear exchanges [4]. Given that the exchange of even a few hundred moderate yield (15 -100kT) weapons targeting cities will lead to billions of deaths, why do we still have huge stockpiles of these weapons, and why are we, the Russians, Chinese, and others still modernizing or increasing our arsenals? [5]
The answer may have its roots in politics, fear and denial. No politician wants to be seen as weak, and at the same time many are fearful that unilateral action would lead to a vulnerability that would be exploited by the other side. It is seen as weak to unilaterally scrap our nuclear warfare capabilities, even though were our enemies to respond by launching a debilitating attack on us, they would doom themselves as well. The reluctance to take determined action to reduce nuclear weapons stockpiles also results from not understanding probability. We've gone 70+ years without having a nuclear war, it is argued, so the probability of having one is demonstrably low. Unfortunately, an event of low probability is just as inevitable as one of high probability; the only difference is in the waiting time. Moreover, just because an event is improbable, it does not necessitate our having to wait a very long time to realize its occurrence. Adherence to the contrary is an example of a form of the Gambler's Fallacy, where faulty logic leads to an expectation that turns out to be false.
Perhaps the most famous of all examples of the Gambler's Fallacy was the occurrence of a run of 26 "blacks" at the roulette wheel of the Monte Carlo Casino on August 18, 1913. The probability of such an event occurring for a fair wheel is about 1 in 1.37 billion, so if the wheel is spun 1,000 times a day the expected waiting time for such an event is over 187 years. As the Casino opened in July 1865, such an event was unlikely to occur within a mere 48 years after the first spinning of the wheel, but it did. This illustrates that even when the probability function is known, the timing of the event cannot be predicted. The problem with an accidental nuclear war, and even to some degree with a deliberate one, is that we can only guess as to what the true probability function is, and therefore cannot predict with confidence even something as basic as the probability that it will happen in some time interval.
Now the custodians of the various nuclear arsenals are united in their assertions that everything humanly possible has been done to prevent an accidental nuclear war, and point to the fail safe [sic] mechanisms in place, human reliability programs, and risk analyses they perform. The problem with all that is, that the possible chains of events leading to the start of an accidental nuclear war are infinite in number, and the number of possibilities conceived of and guarded against, even if hypothetically with 100% effectiveness, is finite. One can point to examples where unconsidered, unpredictable events led to the near initiation of a nuclear war. Here are two: as a result of failure to account for the possibility that the BMEWS radar can detect the moon, a presumptive massive Soviet first strike was about to trigger an all-out US response, had some unnamed US officer not recalled seeing in the news that Khrushchev was in New York at the moment; the other, when Soviet satellite infrared detectors declared a multiple missile US launch based on sunlight reflecting off clouds, the war being averted because LtCol Stanislav Petrov reasoned the strike was not large enough [6].
Then there is the possibility that a nuclear war will be started deliberately. Vladimir Putin has repeatedly threatened to start a nuclear war as part of his effort to restore the Russian empire, and we all know that Donald Trump and his most loyal followers are science deniers, and are therefore not deterred by predictions of a calamity. Indeed, during his first term in office, Trump threatened to obliterate North Korea, an action that would probably elicit nuclear responses by both Russia and the PRC. Unfortunately, the possibilities for initiating a nuclear war include other scenarios besides unilateral actions by the US or Russia.
Between the two scenarios, a war triggered by accident or by a psychopath, a future planet-devastating nuclear exchange is certain to occur, and we cannot reliably estimate how much time we have until it takes place. Therefore, it is incumbent upon us to demand an immediate cessation of nuclear arsenal expansion and maintenance, and the formulation of a process for international nuclear disarmament. Part of that process will necessarily involve making processed Uranium unavailable except in tiny quantities to support scientific research. That will entail the abandonment of Uranium mining, the decommissioning of all Uranium235- and Plutonium-fueled nuclear reactors, and the effective disposal of Uranium and Plutonium fuel stocks.
Notes:
[1] https://www.imdb.com/title/tt0057012/
[3] https://doi.org/10.1029/2019JD030509
[4] https://www.science.org/doi/10.1126/sciadv.aay5478
[5] Readers of Closing the Loop will probably make the connection between nuclear winter and the geoengineering stratagem of stratospheric aerosol injection (SAI). In both cases, large quantities of aerosols injected into the stratosphere cause reductions in global temperatures for time spans on the order of a year. Nuclear winter can be properly thought of as another form of SAI, with ca ten times the material, using a material ca ten times as effective as those envisioned for SAI. It is not logically consistent to accept the evidence for SAI (e.g., large volcanic eruptions) while denying the likelihood of nuclear winter.
[6] More incidents are mentioned in a recent animation about how a nuclear war might be started:
Let's collaborate?
typo?
"...This nuclear winter effect has been studied...with the not only the confirmation ..."