The most serious detrimental effects a nuclear war would have on the environment are radioactive fallout, depletion of the ozone layer, and the possibility of nuclear winter. The extent of the damage is hard to predict, since there are so many variables involved. For example, the range and severity of fallout from multiple nuclear explosions depends on how many warheads are exploded, whether they explode on the ground or in the air, whether there is rain soon after the explosion, which direction and how strongly the wind is blowing, what the warheads fall on, and how many megatons each warhead has. Even with the results of nuclear weapons testing, it's still difficult to predict what will happen if multiple bombs are set off in urban areas, instead of single bombs, as was the case in Hiroshima and Nagasaki, or single bombs set off in remote and/or non-forested areas, as has been the case with the nuclear tests performed so far. The creation of a nuclear winter is even more uncertain. The original study that caused so much uproar remains controversial, but the possibility of a nuclear winter remains. While there is uncertainty in the extent and severity of long-term consequences, the short term environmental damage can be predicted.

     Because urban areas, as population centers or as sites of military installations, would be the first targets in a nuclear attack, the immediate damage to ecosystems would be small. Cities are not known for their thriving biodiversity. There might be some damage to animals in ecosystems on the outskirts of the city if they happened to be looking towards the city at the same time as the explosion, since the light from the bomb creates blindness. The most immediate damage to ecosystems would probably be that caused by fire. Some scientists have predicted that fires caused by the heat, pressure, and initial fireballs of the nuclear explosions might spread from the cities to the forests (in temperate and tropical regions). The subsequent damage to the water and soil as erosion ran rampant on the unprotected ground would cause even more damage. Others disagree with the forest fire theory, pointing out that in all the intensive bombings that occurred during WWII, only a few firestorms occurred, and massive burnings of forest never took place (Ervin, et al., 1962). They also claim that cities nowadays are made out of nonflammable materials such as metal and concrete, so any fires that were started would quickly run out of fuel. The injection of nitrogen oxide into the atmosphere during the atomic explosion is another problem. It would increase acid rain, probably a greater and longer lasting danger to water ecosystems than radioactive fallout.

     Radioactive fallout would have a greater chance of reaching rural and wild areas than fire would. If the bombs detonate in the air, as they did in Hiroshima and Nagasaki, they will create a fireball. This fireball will not reach the ground. It, and its associated dust, smoke, and debris, will ascend and disperse into the atmosphere. The radioactive materials it contains will, over time, spread out until they are too diluted to do any harm. However, in the mean time fallout is a real danger. When rain or snow occurs before enough time has elapsed to dilute the radioactive materials beyond the point of significant harm, the materials are washed out of the air in thick concentrations, creating radioactive ‘hot spots' on the ground (Radiation Effects Research Foundation). Because the radioactive debris is carried by the winds, these hot spots are unlikely to occur over the site of the bomb blast itself. Instead, it will fall on outlying suburban and rural areas.

     So what should be done with these sites? In Hiroshima and Nagasaki, the radiation at the bomb sites and surrounding hot spots is so low that it takes months to detect. Sophisticated machines have to be used to tell it apart from the background radiation present everywhere. The radiation here has, however, taken fifty years to fall to such low levels. The U.S. Department of Energy has proposed that current nuclear waste sites, generally much more toxic than nuclear bomb sites, be made into animal refuges instead of being cleaned, which is a more costly and sometimes a more environmentally damaging solution (Makhijari and Gopal, 2001). This proposal does not consider the genetic effects of radiation on the animals in radioactive waste sites. Nor does it consider the possibility of contaminated materials leaving the site. In Sellafield, Britain, pigeons roosting at a nuclear power plant became contaminated by radioactive waste. The pigeons often left the power plant to roost above a garden in a nearby town. When the pigeons' high radiation levels were discovered, both they and the garden they roosted above, into which their droppings had fallen, had to be declared radioactive waste. There is also the danger of radioactive waste escaping in smoke from a fire, or, if the site is above the average height of its watershed, in the streams, creeks, and rivers.

     Nuclear winter is the most frightening possible consequence of a large-scale nuclear war. It received widespread attention for the first time in 1983, with the publication of the TTAPS (named for the author, R.P. Turco, A.B. Toon, T.P. Ackerman, J.B. Pollack, and C. Sagen) report, "Nuclear Winter: Global Consequences of Multiple Nuclear Explosions." The nuclear winter theory predicts that the smoke from multiple nuclear detonations would block out the sun, lowering temperatures over the entire earth. Because of this prediction, peace activists embraced the theory, reasoning that if nuclear war would kill everyone instead of just the people of the country under attack, nations' own self-interest would prevent them from starting a nuclear war. Some scientists and military strategists poo-pood the idea, claiming that the experiment was flawed and therefore there was no reason to start disbanding nuclear weapons stockpiles. More studies were immediately undertaken.

     Nuclear winter, at its most extreme, predicts the injection of soot into the stratosphere, obscuring the sun and plunging the earth into unseasonably cold temperatures. As multiple nuclear bombs are detonated the waves of heat and pressure, and the initial fireballs, would cause conflagrations (fires covering a large area) and firestorms (smaller fires that burn intensely). The smoke and soot from these fires would blanket the stratosphere, deflecting sunlight while allowing thermal radiation from the earth to escape. Temperatures would fall as much as 10 to 20 degrees Celsius in the northern mid-latitudes, and as much as 35 degrees Celsius in some areas of this region (Turco, et al. 1990). The effect is comparable to the dust thrown up by the asteroid that is believed to have killed the dinosaurs. With a reduction of as much of 99% of sunlight (Harwell, 1984) in some places, and general overcast conditions lasting from days to over a year in the most severe simulations, most life forms on earth would suffer. On the up side of things, global warming would no longer be a concern.

      The huge drop in temperature would have devastating effects on the ecosystem. Perennial plants would expend most of their energy reserves attempting to become dormant in response to the sudden cold weather. Trees, able to stand extremely cold periods during normal winters, would probably survive a spring or summer temperature drop but would suffer from decreased growth and might not produce seeds. Crops, of course, would die if the temperature came near freezing (Birks and Ehrlich, 1990). Though sub-freezing temperatures would occur only in some areas, there would be an overall drop in temperature world wide. Plants in coastal areas would have the best chance of survival, since the oceans, with their large heat capacity, would act as heat reservoirs and keep the temperature more moderate.

      The plants that survived the drop in temperature would then have to deal with the decreased sunlight. The lack of light available for photosynthesis would slowly starve them to death. With a ninety-nine percent decrease in light, there would be massive plant die-outs. Even with only an eighty to ninety percent decrease in light, plants would be unable to produce seeds for the coming year. Animals and insects dependant on the plants for food would die as their food sources disappeared. Carnivores would do well at first, as their prey became weak, but as the prey animals died, they too would suffer from starvation (Birks and Ehrlich, 1990). The extinction of thousands of species is possible.

      This is what the TTAPS report of 1983 suggested, anyway. However, even when it first appeared this report was subject to controversy. Other scientists pointed out that it was based on a modal of the earth as a waterless planet with no more topography than a smooth billiard ball (Seitz, 1986). This featureless earth modal means that the way air circulates was probably oversimplified, and that the effects of the oceans as a heat reservoir were not taken into account at all. It was also pointed out that for the most severe of the TTAPS versions of nuclear winter to occur (also the version most publicized), a chain of some 40 variables would have to take place. The TTAPS scientists later produced another report confirming their earlier findings, but the probability of nuclear winter is still under dispute.

      A third problem associated with the introduction of chemicals into the stratosphere is that of ozone depletion. Nitrogen and hydrogen oxides created by the heat of the explosion could be injected into the stratosphere, where they would act as catalysts in the destruction of ozone. The ozone layer, now on the mend, could suffer from a 20% decrease in the case of a 50 megaton nuclear war, or a 50% to 70% decrease in the case of a 500 megaton war. If a nuclear winter also occurred, then we would be faced, ironically, with cancerous UV-B radiation as soon as the sun-blocking soot clouds settled out of the atmosphere and ended the winter.

      Few studies have been done on nuclear winter since the late eighties and early nineties (Phillips, 2000). The massive global catastrophe that was predicted in the TTAPS report seems less probable. Instead, a ‘nuclear autumn' appears to be a more likely occurrence. Examinations of the effects of forest fires and volcanic eruptions, both events that propel dust particles into the stratosphere, have shown that cooling of up to 15 degrees Celsius (in local areas) can be produced (Robock, 1989). Neither the TTAPS scientists nor their critics have been proven conclusively right or wrong in the years that followed their original report. Many scientists say that even with all the testing of nuclear weapons that has occurred, there are simply too many variables to predict what would actually happen if massive nuclear explosions took place, other than to try it and find out. No one wants to do that. Instead, it is generally excepted that short of such massive nuclear strikes, the effects of today's powerful bombs on the complicated and interconnected ecosystem are hard to predict, but that nuclear winter would probably not occur, at least in the degree of severity reported by TTAPS.

Written by Ali Jones