equated to the explosion of a given number of thousands (kilo-) or millions (mega-) of tons of TNT, a powerful chemical explosive then used in conventional bombs. In principle, any explosion can be so equated; for example, the violent eruption of Oregon’s Mount St.Helens’ in 1980 was about 20 megatons on this scale.
But a nuclear weapon’s energy release is fundamentally different in character from that of a chemical or volcanic explosion. An explosive nuclear reaction takes place in less than a millisecond, during which time the bomb material is heated to over six million degrees Kelvin, greater than the temperature of our Sun’s photosphere. This leads to a unique three – stage release of energy.
First, this heating produces an incredibly intense irradiative flash in all wavelengths. Radiation in the shorter (more energetic) wavelengths (energetic X-rays or gamma rays) penetrate deeply, and can damage living tissue not protected by thick concrete or metal at a very considerable distance; naval observers report that after a five – megaton American test in the Pacific, they had a “tan line” around their military dogtags, even though they were 25 miles from the blast. Had they been much closer, these intense rays (sometimes called “prompt radiation”) would have led to the radiation sickness or death described below.
If the explosion takes place near the top of or above the atmosphere, these high – energy gamma rays strip the electrons from the atoms of the air itself, creating an enormous electric surge known as the “electromagnetic pulse”, powerful enough to destroy virtually every electrical device. The Internet and all systems connected to it, computers, telephone networks, power grids, navigation systems, and even automobile ignitions would be “fried” over an area the size of many states. In this way, a few thermonuclear bombs exploded above the atmosphere could bring modern industrial civilization to a halt without causing a single direct casualty.
The flash in visible wavelengths is so intense that it can produce permanent blindness even when viewed through sun filters. The infrared (heat) flash of even a small atomic bomb can be felt on the skin ten miles away. Up close, it is instantly lethal. Some of the most dramatic artifacts from the Hiroshima bomb were the carbon – particle human silhouettes etched into stone – all that was left of those within the fatal radius of the bomb’s flash.
The enormous surge of heat immediately reacts with the atmosphere, producing the second major effect: a supersonic blast wave that can destroy most buildings miles away. After the Hiroshima bomb, virtually no structure was left standing within a mile radius of the bomb; at even greater distances weaker structures collapsed, killing or maiming those trapped within. In the case of a large thermonuclear bomb, almost every unreinforced structure as far as ten miles away would collapse, and windows would explode inward into lethal shards at even greater distances. As the anti – nuclear campaigner Helen Caldicott once said, “bodies from what was left of the buildings would litter was left of the streets”.
But the most insidious effect of a nuclear weapons explosion has no counterpart in a chemical or volcanic blast, however large. A nuclear explosion results in the release of enormous amounts of ionizing radiation. First, there is the “prompt radiation” produced by the blast itself. For very large bombs, without protection this radiation can be lethal well outside the blast radius. But the bomb produces so – called “secondary radiation” as well. The ultra – energetic nuclear particles released by the explosion radiate the surrounding material, and the intense heat causes this debris to rise upward in a giant cloud. Much of this cools when it reaches the stratosphere, falling back to earth as intensely radioactive “primary fallout”. Many of those who managed to survive the heat wave and blast will succumb to the effects of “radiation sickness”. Destruction of the DNA in the body’s rapidly – growing cells leads to hair loss, diarrhea, soft tissue and internal bleeding, pulmonary edema, and severe damage to the immune system. If the exposure is great enough, it can fatally impair the vital functions of the liver, lungs, heart, and nervous tissue, leading to a lingering, painful death described by one doctor as “cancer of the everything”.
Especially with the larger bombs, a portion of the radiation is forced into the stratosphere, and is then distributed randomly by the upper atmosphere circulation. While its descent to earth seldom produces acute radiation poisoning, a number of radioactive elements created by a nuclear explosion are absorbed by living organisms and accumulate up the food chain, and thus inevitably concentrating in human food. Radioactive iodine concentrates in the thyroid, strontium in the bones, cesium in the heart muscle, and uranium in the kidneys. Even halfway around the world, enough of these elements can accumulate in the human body to impair organ functioning and increase dramatically the incidence of cancer. And even tiny amounts of plutonium absorbed into the body can affect male sperm in such a way as to increase the incidence of cancer among the victim’s children. It is estimated that somewhere between 20,000 and 200,000 premature deaths worldwide were caused just by nuclear testing in the atmosphere between 1945 and 1961.
All of this can be produced by the detonation of single nuclear weapons. Were a very large number to be detonated simultaneously, as in a war, a tertiary effect would be produced that would be not merely lethal, but potentially species – threatening. In the 1980’s, atmospheric scientists showed that the explosion of several hundred thermonuclear bombs at once would eject enough dust and soot into the atmosphere to temporarily obscure the sun and produce a rapid cooling of the atmosphere, an effect after huge volcanic eruptions in historical times. While the precise magnitude of this cooling can only be roughly estimated, scientists believe that the detonation of only a few hundred of the more than 10,000 large nuclear warheads in the global stockpile would cool the atmosphere enough to cut global agricultural production severely for a number of years, while inducing catastrophic climatic events. In the words of one analyst, “in a nuclear war, if you don’t fry, you’ll freeze, and if don’t freeze, you’ll starve”.
After recounting this litany of horror, one can sympathize with the sorrowful remark Einstein made toward the end of his life: “If I had only known, I would have become a watchmaker”.
- Samuel Glasstone, The Effects of Nuclear Weapons Washington, D.C.: U.S. Atomic Energy Commission, 1957. (2 nd ed., 1963; 3 rd ed., 1977, reprinted 1983) [n.b. – this book has long been out of print, but used copies are readily available from Amazon and similar outlets. It remains the definitive source.]
- “What if it Happens Here” Los Angeles, CA: PowerPoint presentation produced by the California Chapter of Physicians for Social Responsibility, 2002.
- “The Atomic Café”, feature movie re-released in DVD format in 2002. The last scene is a dramatic visual montage of the effects of a number of nuclear detonations.
- Federation of American Scientists’ “Bomb-a-City” calculator: