Nuclear War: Its Environmental Impact

Abstract

This paper examines the widespread environmental effects, sensu stricto, that would result from a large-scale nuclear war and the resultant ecological impacts. Singled out for analysis are the effects of wildfires, radioactive fallout, enhanced ultraviolet radiation, loss of atmospheric oxygen, gain in atmospheric carbon dioxide, and reductions in sunlight and temperature; also of combinations and ramifications of these adverse phenomena. In a large-scale nuclear war, wildfires initiated by the heat of the nuclear explosions would burn on perhaps 2 % of the rural portions of the targeted countries' lands. These conflagrations would kill off much of the flora and fauna on those lands, and would cause long-term site debilitation through loss of soluble nutrients (`nutrient-dumping') and soil erosion. Radioactive fallout derived from surface bursts and destroyed nuclear reactors would for several days subject perhaps 10 % of the rural portions of the targeted countries to nuclear radiation (gamma, beta, etc.) at levels that would be lethal to all exposed vertebrates and to some categories of vegetation---for example, coniferous forests. At least 1 % of the territory of these countries would remain uninhabitable to humans for many decades. The killed vegetation would in time provide the fuel for further wildfires. Ultraviolet radiation-B (UV-B) would be intensified perhaps threefold throughout the northern hemisphere (and to a lesser extent in the southern hemisphere) through depletion of stratospheric ozone by oxides of nitrogen generated by the fireballs created by atmospheric nuclear explosions, diminishing to normal levels only over a period of some years. This UV-enrichment would debilitate both the agricultural and natural ecosystems on land, and perhaps also those in the ocean, for some years. Atmospheric oxygen would be reduced through respiration that would be unbalanced by photosynthesis, and in other ways including conflagration, but at biologically and ecologically inconsequential levels. Atmospheric carbon dioxide would be enhanced through the same process of respiration unbalanced by photosynthesis, and in other ways including conflagration, by somewhat less than 20 % (perhaps quickly adjusting to somewhat less than 10 %). This CO2-enrichment would have only minor ecological effects, but would presumably contribute to the coming global `greenhouse' problem. Sunlight would be partially obscured by smoke from urban and industrial fires, etc., in great moving patches throughout the mid-latitudes of the northern hemisphere for up to a few weeks. Although such diminution of light would have little effect per se on the biotas, it might do so secondarily by causing more or less drastic reductions in temperature. Surface temperatures might sporadically drop conceivably by as much as several tens of degrees Celsius in the interior of continental land masses of the mid-latitudes of the northern hemisphere for up to a few months, whereafter modest temperature depressions might continue for a year or so. Thus, if a large-scale nuclear war were fought especially during the growing (summer) season, the reduced temperatures would kill or injure crops, livestock, and the natural flora and fauna. Among the natural ecosystems, those of deciduous (broad-leafed) forests would be most seriously affected, with ecological recovery taking a considerable number of years. In the considerably less likely event that the cold wave would extend into the tropical (hitherto frost-free) regions, ecological damage would be catastrophic. The various predicted environmental perturbations are of such magnitude in areal extent, intensity, and diversity that they would be sure to produce a variety of unforeseen ecological effects, especially in their interactions. The human survivors of a large-scale nuclear war would have to cope with a bleak and widely inhospitable environment indeed. It is concluded that nuclear war must be avoided, not only as the ultimate insult to human civilization, but also as the ultimate insult to nature.