War, environmental effects of

War and similar conflicts have long been an activity of humans, and is referred to in the earliest historical records. Wars involving hunter-gatherer and early agricultural cultures included clashes between clans and village groups. This sometimes led to the deaths of some participants, as has been observed up to the present century in such places as New Guinea and Borneo. In marked contrast, modern warfare involving advanced technological societies can wreak a truly awesome destruction—about 84 million people have been killed during the wars of the twentieth century.

The conflict that has been the most destructive to human life was World War II (1939-1945), during which about 38 million people were killed. World War I (1914-1918) resulted in about 20 million deaths, the Korean War (1950-1953) about 3 million, and the Vietnam War (1961-1975) about 2.4 million.

In addition to having awful consequences for people and their civilizations, modern warfare also causes terrible environmental damages. These include the destruction caused by conventional weapons, effects of the military use of poisonous gases and herbicides, and petroleum spills. In addition, the potential consequences of nuclear warfare are horrific—a nuclear holocaust could kill billions of people and might also result in climate changes that would cause a collapse of biospheric processes.

Destruction by conventional warfare

Enormous amounts of explosive munitions are used during modern wars. An estimated 23.1 million tons (21 million metric tons) of explosives were expended during World War II, 36% of that by United States forces, 42% by the Germans, and 22% by other combatants. About 3.3 million tons (3 million metric tons) were used during the Korean War, 90% of that by U.S. and Allied forces. About 15.4 million tons (14 million metric tons) were used during the Vietnam War, 95% of that by U.S. and South Vietnamese forces. During the Gulf Conflict, several months of bombardment by U.S.-led coalition forces resulted in 88,000 tons (80,000 metric tons) of explosives being dropped on Iraq. Although not well-documented, the explosion of such enormous quantities of munitions during these wars caused great damages to people, buildings, and ecosystems.

Much of World War I, for example, was waged in an area of coastal lowland in Belgium and France known as the Western Front. This was a terrible theater of war, which involved virtually static confrontations between huge armies that fought back and forth over a well-defended landscape webbed with intricate trenchworks. Territorial gains could only be made by extraordinarily difficult frontal assaults, which resulted in an enormous waste of men and material. Battles were preceded by intense artillery bombardments, which devastated the agricultural lands and woodlands of the battlefields.

One observer described the ruined terrain of an area of Belgium known as Flanders in this way: "In this landscape nothing existed but a measureless bog of military rubble, shattered houses, and tree stumps. It was pitted with shell craters containing fetid water. Overhead hung low clouds of smoke and fog. The very ground was soured by poison gas." (cited in Freedman, 1995). Another passage described the destruction of a forest (or copse) by an artillery bombardment: "When a copse was caught in a fury of shells the trees flew uprooted through the air like a handful of feathers; in a flash the area became, as in a magicians trick, as barren as the expanse around it." These were common observations, and they typified the damages caused by explosions, machines, and the mass movements of men determined to kill each other.

About half of the munitions used during the Vietnam War was delivered by aircraft, half by artillery, and less than 1% from offshore ships. United States forces dropped about 20 million aerial bombs of various sizes, fired 230 million artillery shells, and used more than 100 million grenades and additional millions of rockets and mortar shells. Of course, these caused enormous physical destruction to the built environment of cities and towns, and to agricultural and natural environments. During 1967 and 1968, for example, about 2.5 million craters were formed by 500- and 750-lb (227- and 337-kg) bombs dropped in saturation patterns by high-flying B-52 bombers. Each plane sortie produced a bombed-out area of about 161 acres (65 ha). Eventually about 21.6 million acres (8.1 million ha) or 11% of the landscape of Indochina was affected in this way (this includes Laos and Vietnam). Craters were about 16 yd (15 m) wide and 13 yd (12 m) deep, and they usually filled with fresh water. In addition, the explosions often started forest or grassland fires, which caused extensive secondary damages.

Some animals have been brought to the brink of extinction through warfare. For instance, the last wild Pere David's deer (Elaphurus diavidianus ) were killed during the Boxer War of 1898-1900 in China. The European bison (Bison bonasus ) was almost rendered extinct by hunting during World War I to provide meat for troops. More recently, warfare has led to lawlessness in much of Africa, allowing well-armed gangs of poachers to cause white rhinos (Ceratotherium simum ), black rhinos (Diceros bicornis ), elephants (Loxodontia africana ), and other species to become critically endangered over much of their range. These animals are hunted for their horns, tusks, and other valuable body parts.

Although the effects of war on wild animals have mostly been damaging, there have been a few exceptions. Usually this happened because of decreased exploitation—men were too busy trying to kill each other to bother with hunting other species. For example, the abundance of game-birds in Britain increased markedly during both World Wars because of decreased hunting pressures. So did fish stocks in the North Atlantic, because fishing boats were subject to attacks.

The legacy of unexploded munitions

Many aerial bombs and artillery shells do not explode and cause a lingering hazard on the landscape. These problems are made much worse by the use of explosive mines in warfare, because few of these buried devices are recovered after the hostilities cease, and they continue to be an explosive hazard for people and domestic and wild animals for decades. Modern anti-personnel mines are extremely difficult to find, largely because they can contain as little as one gram of metal, which makes it hard to detect them magnetically.

Chemical weapons in warfare

Antipersonnel chemical warfare occurred on a large scale during World War I, when more than 220.5 million lb (100 million kg) of lethal agents were used. These were devastating lung poisons such as chlorine , phosgene, trichloromethyl chloroformate, and chloropicrin, and the dermal agent known as mustard gas. These poisons caused about 1.3 million casualties, including 100,000 deaths.

Lethal gases were also used during the Iran-Iraq War of 1981-1987, mostly by Iraqi forces. The most famous incident involved the Kurdish town of Halabja in northern Iraq, which had rebelled against the central government and was aerially gassed with the nerve agents sabin and tabun, causing about 5,000 deaths.

The nonlethal "harassing agent" CS (or o-chlorobenzolmalononitrile) was used by the U.S. military during the Vietnam War. About 20 million lb (9 million kg) of CS was sprayed over more than 2.5 million acres (one million ha) of South Vietnam, rendering treated places uninhabitable by humans, and likely wild animals, for up to 45 days.

In addition, extensive areas of Vietnam were treated with herbicides by U.S. forces to deprive their enemy of forest cover and food production. More than 3.5 million acres (1.4 million ha) were sprayed at least once, equivalent to about one-seventh the area of South Vietnam. Most of the treated area was mangrove or upland forest, with about 247,000 acres (100,000 ha) being cropland. The most commonly used herbicide was a 50:50 mixture of 2,4,5-T plus 2,4-D , known as Agent Orange . More than 55 million lb (25 million kg) of 2,4-D and 47 million lb (21 million kg) of 2,4,5-T were sprayed in this military program. Because the intent was to achieve a longer-term defoliation , the application rates were relatively high, equivalent to about 10 times the rate normally used in forestry.

The herbicide spraying caused great ecological damages, with effects so severe that critics of the practice labeled it "ecocide," i.e., the intentional use of anti-environmental actions over a large area, carried out as a tactical component of a military strategy. The damages included loss of agricultural lands for many rural people, as well as extensive deforestation , which caused severe but almost undocumented effects on the native biodiversity of Vietnam.

Because the 2,4,5-T used in the herbicide spraying was contaminated by a dioxin chemical known as TCDD (2,3,7,8-tetrachlorodibenzo-p -dioxin), there was also a great deal of controversy about the potential effects on humans. As much as 357 lb (162 kg) of TCDD was sprayed with herbicides onto Vietnam. Although there have been claims of damages caused to exposed populations, including U.S. military personnel, the scientific studies have not demonstrated convincing linkages. Although the subject remains controversial, it seems likely that the specific effects of TCDD were small in comparison with the overall ecological effects of the use of herbicides in the Vietnam War.

Effects of nuclear warfare

Nuclear weapons have an enormous capability for destruction of humans, their civilization, and natural ecosystems. This was recognized by John F. Kennedy during a speech to the United Nations in 1961: "Mankind must put an end to war, or war will put an end to mankind."

The world's nuclear arsenal peaked during the 1980s, when the explosive yield of all weapons was about 18,000 megatons (Mt) of TNT-equivalent. This was more than 1,000 times larger than the combined yield of all conventional explosives used during World War II (6.0 Mt), the Korean War (0.8 Mt), and the Second Indochina War (4.1 Mt). The late-1980s nuclear arsenal was equivalent to 3–4 tons (2.7–3.6 metric tons) of TNT per person on Earth.

Thankfully, the cessation of the Cold War has led to substantial reductions in the world's nuclear weaponry, which has declined from a total explosive yield of about 18,000 Mt in the 1980s to about 8,000 in the mid-1990s. There were about 64,000 strategic and tactical devices in 1983, but 27,000 in 1993, and planned reductions to 11–19 thousand in 2003.

Nuclear weapons have twice been used in warfare. This involved bombs dropped by U.S. forces on Japan, in an action that brought World War II to an earlier end than would have occurred otherwise. The first bomb had an explosive yield equivalent to 0.015 Mt of TNT and was dropped on Hiroshima on August 6, 1945, and the second (0.021 Mt) was dropped on Nagasaki a few days later. The Hiroshima bomb killed about 140,000 people, while the Nagasaki device killed 74,000. The combined effects of blast and heat destroyed about two-thirds of the buildings in Hiroshima, and one-fourth of those in Nagasaki. Although enormous in comparison with conventional bombs, these nuclear devices were small in comparison to the typical yield of modern strategic warheads, which average about 0.6 Mt and range to 6 Mt.

Not surprisingly, people are concerned about the likely consequences of a large-scale nuclear exchange. One commonly used scenario of a nuclear war is for a limited exchange of 5,000–6,000 Mt, most of which would be exploded in the Northern Hemisphere. The predicted effects on people include the deaths of about 20% of the world's population, including as much as 75% of the population of the United States. The principal cause of death would be thermal radiation, but effects of blast, fire, and ionizing radiation would also be important. Virtually all survivors would be injured by these same forces. Such an overwhelming loss of human life, coupled with the physical devastation, would transform civilization.

It has also been suggested that a nuclear war could result in a global deterioration of climate, which would cause additional severe damages. The climatic effects might be caused by various influences of nuclear explosions, but especially the injection of large quantities of sooty smoke, inorganic particulates, and gases into the atmosphere . These could interfere with the planet's absorption of solar energy and its re-emission of infrared energy. These potential consequences of nuclear warfare have been studied using computer models of the type that are used to model the effects of emissions of carbon dioxide and methane on Earth's greenhouse effect . In general, the predictions are that nuclear war could cause a global cooling, or a "nuclear winter," which would cause widespread damages to agriculture and natural ecosystems. The longer-term climatic damages would add to the enormous destructions that were caused by blast, thermal radiation, fire, and ionizing radiation within a short time of the nuclear exchange.

Humans have probably engaged in warfare throughout their history, and regrettably we appear likely to continue to do so into the future. Fortunately, the catastrophic effects of modern technological warfare are being increasingly recognized, and many nations have been making progress in avoiding conflicts, particularly amongst the world's most heavily armed nations. Because nuclear war has especially horrific consequences, recent treaties on non-proliferation of nuclear weapons and nuclear arms reductions provide real prospects in this regard.

[Bill Freedman Ph.D. ]