by Joe Buff, MS, FSA
A game-changer in the bitter contest for thermonuclear supremacy between the United States and the Soviet Union was the discovery, in the late 1970s, of the utter horror called nuclear winter. Advances in worldwide meteorological modeling and computer science allowed realistic simulations of what would happen to Planet Earth in the aftermath of a major nuclear war. The results were appalling. It didn’t matter if you were capitalist or communist or non-aligned, First World or Second World or Third. Detonating enough nuclear warheads with enough big yields in enough different places would create a globe-choking blanket of ultra-persisting stratospheric smoke, dust, and aerosols.
All sunlight would be blocked for years. Darkness would reign 24/7/365. Temperatures would plunge so far below zero Fahrenheit even at the equator that all bodies of water would freeze solid to a depth of ten feet. All plants and animals would die. So would the billions of human beings who might have somehow avoided the prolonged, deadly radioactive fallout that followed the fierce X-rays and gamma rays of each bomb’s detonation, the searing heat of the fireballs and resultant firestorms, and the massive blast waves that rupture buildings and bodies alike.
It is no coincidence that, when this horrible realization sank in, the two adversary superpowers cooperated enough to reduce their bloated nuclear arsenals from a frightening high, of some combined 70,000 deliverable warheads, down to the minimum needed for effective mutual deterrence of large adversaries in the modern world, the 1550 deployed strategic warheads apiece allowed under the New START treaty. New START is about to expire. A keen awareness of the dangers of nuclear winter, beyond the potentially extincting dangers of nuclear war itself, should inform concerted international efforts to keep that important treaty in force, or at least obeyed de facto.
Some advocates of unilateral total nuclear disarmament by America try to take these arguments one step further — a step too far. They say that the reality of nuclear winter effects renders all nukes completely unusable by any party, and thus makes them useless, irrelevant to modern defense. But alas, this is not true. The situation with nuclear weapons — their moral use for deterring attack and preventing blackmail (good things) versus their immoral use for perpetrating attacks and committing blackmail (bad things) — is much more complex and nuanced. It cannot and must not be adulterated, dumbed down into simplistic political campaign slogans, monosyllabic bumper stickers, and chants by emotionally manipulated stadium crowds and street demonstrators.
It is not necessarily true that any initial use of nuclear weapons, in some small taboo-breaking 21st century first-strike attack, will inevitably lead to global thermonuclear holocaust — but it isn’t necessarily true that it won’t. This uncertainty creates severe risks for everybody, but it also implies pernicious opportunities for bad actors.
Defenders of freedom cannot ever be sure that a limited nuclear war that someone else starts will stay limited — relatively small in the number of warheads set off, their yield sizes, and their geographic areas of destruction. The defender might be dissuaded from making any nuclear counter-strike at all, or make an overly weak one if a tyrant does nuke them first, for fear that any added nuclear detonations may help cause collective Armageddon. On the other hand, enemies of freedom who own nuclear arsenals cannot ever be sure that a limited nuclear war they start will not stay limited. They might be encouraged to make a limited nuclear first strike against a victim state, gambling that the result will remain a limited nuclear conflict from which they come out on top domestically and geopolitically. Remember, lovers of freedom: Tyrants are not casualty averse. Human history and clinical psychology teach us that sociopath dictators actively crave sending millions of their own citizens to their deaths in wars of conquest — look at Kaiser Bill and Adolf Hitler as just two tragic examples.
It is particularly unwise for a defender to rely on the well-publicized human extinction phenomenon of a global nuclear winter as a mechanism self-deterring any belligerent nuclear attacker against making any nuke first strike at all. The flip side of this, a small saving grace at best, is that it is equally unwise for such an attacker to rely on this nuclear winter risk to deter the defender against retaliating. This is because there is, unfortunately, a substantial breaking point — Planet Earth’s own redline — of total warhead numbers and yield megatonnage, set off over a short period in a widespread nuclear conflict, below which local and regional effects are (of course) quite devastating, but with which a global nuclear winter does not occur.
Some commentators note that this nuclear-winter breaking point exists, but they specifically refrain from using their forecasting models to try to estimate it. This is for fear of empowering some nuclear-armed despot in a heinous act of nuclear blackmail or outright attack where he or she “wins.” The despot could launch, or threaten to launch, a first strike of exactly that breaking-point magnitude, putting the world at the tipping point where any nuclear retaliation at all against him/her could mean the end of life on Earth. But ipso facto, the idea of this breaking point is indeed in the literature. Despots can be very smart and can have highly educated, imaginative and creative advisers and supercomputer programmers of their own to do the calculations — and nuclear deterrence policy and posture best practice drafting is no place for the old superstition that naming the Devil will call him.
The same literature suggests that a soft number like roughly 50 megatons or less, of total yield set off by both sides in a nuclear war, might very well not lead to the dreaded months- or years-long global hard freeze, perpetual darkness, worldwide total crop failures and livestock deaths, and ozone layer destruction that a 5,000-megaton conflict would certainly inflict equally on both sides and all innocents. The great science-popularizer Carl Sagan, in his research, found that approximately 1,000 warheads set off quickly through much of the Northern Hemisphere, where each warhead is a hydrogen bomb (yield of at least about 100 kilotons), is needed for a true nuclear winter event.
Fortunately, any such breaking-point calculation will at best be very soft. This assures a cushion for substantial nuclear retaliation by defenders, whatever the above-mentioned homicidal but not suicidal despot does. This is especially true if said retaliation is delayed by the victim state(s), as is always an option, for many months. Defender nuclear crews should be well supplied with everything needed to get them through the months-long wintry aftermath possible from the aggressor’s attack, and through a whole new nuclear winter possibly caused by their own counter-attack. At such time as the pervasive, persistent stratospheric soot, dust, and aerosols subside enough to allow an adequately-sized nuclear retaliation, the counter-strike can be made. This prospective fact should serve well to deter the attacker regime, in advance. No state government is a monolith. If a dictator loses his/her mind, a crucial circuit breaker remains in the form of senior subordinates who make the rational choice of survival over sycophantic species suicide.
The very possibility of a global nuclear winter should be extremely alarming to everyone. But for anti-nuclear advocates to exaggerate the likelihood of nuclear winter occurring from every limited and regional tactical nuclear war that somehow does stay limited is probably counterproductive to effective deterrence and arms control.
One recent newspaper op-ed stated that 100 Hiroshima-size bombs (individually about 12 kilotons), used by each side in a Pakistan-India nuclear war, would cause a worldwide nuclear winter that would last for years. However, the total yield of the 200 fission bombs detonated in this sort of conflict would be well under 2 megatons. None of these fission weapons would produce the high altitude, very long lasting stratospheric smoke needed to obscure the sun long-term on a planet-wide scale. Several early Cold War-era atmospheric nuclear tests set off multi-megaton H-bombs, some with actual yields of 15 megatons (U.S.) or even 57 megatons (USSR) each; nuclear winter did not result. Nuclear winter was only discovered theoretically, in the late 1970s, as a result of environmental and meteorological computer modeling.
The smoke that results from fission bombs mostly stays in the troposphere, below about 38,000 feet altitude, where most weather occurs. Even after a tactical nuclear war, rain and snow of the water cycle will still happen. They will quickly wash the troposphere clean enough for some sunlight to reach the ground over most of the world. Fusion bombs, in contrast, each have a blast that is nominally some thousand times more powerful than that of a fission bomb. That much bigger blast entrains vastly more obscuring material from the ground into the fireball, and into the hurricane-force mushroom cloud updraft from the detonation. In addition, the temperature (heat content) of an H-bomb fusion detonation, peaking at literally hundreds of millions of degrees Centigrade, is higher than that of an A-bomb. This massive thermal energy punch, which causes terrific buoyancy within the atmosphere, propels the cap of the H-bomb’s mushroom cloud (the gradually expanding, cooling fireball) to a much greater, stratospheric altitude. There is no rain or snow in the stratosphere. Violent jet stream winds there keep particulates suspended up high and distribute them worldwide. There they persist until most local ground conditions resemble the South Pole in the depths of its six months of wintry darkness.
No, nuclear winter cannot be counted on as an automatic, apolitical and cost-free, Mother Nature-administered doomsday machine — a total deterrent against all nuclear weapon attacks whatsoever. Expensive, man-made, judgment based (and thus inevitably politicized) effective nuclear deterrence is needed to prop up Mother Nature, and support human and planetary survival.