(January 2001) How can environmental problems contribute to civil unrest and violence? The connection is a complicated one, involving several steps and processes. The research led by Thomas Homer-Dixon at the University of Toronto has focused on how environmental scarcity leads to certain destabilizing social effects that make violence more likely.

Environmental scarcity refers to the declining availability of renewable natural resources such as freshwater or soil. There are three basic ways in which such scarcity can arise:

  • Demand-induced scarcity: Population growth or increasing consumption levels decrease the amount of limited natural resources available to each individual. The population of sub-Saharan Africa, for example, has increased from 177 million in 1950 to 657 million in 2000, shrinking the amount of land and freshwater available to the average person. In the case of Rwanda, demographic pressures created extreme environmental scarcity that played a role in the 1994 genocide.
  • Supply-induced scarcity: Environmental degradation decreases the overall amount of a limited natural resource, decreasing the amount available to each individual. In western China, overgrazing in portions of the Qinghai-Tibet Plateau has combined with drought to degrade precious topsoil over the past several years. Chinese scientists estimate that 900 square miles of land in the region degrade into desert each year. As a result, herders and farmers have found it increasingly difficult to earn a living in the area.
  • Structural scarcity: Unequal access to natural resources in a given society makes them scarce for large segments of the population. In South Africa, the system of apartheid provided whites with 87 percent of the land, while blacks (almost 75 percent of the country's population) lived within restricted areas that accounted for only 13 percent of the land. Resources were also inequitably distributed within the restricted areas, as local elites controlled access to productive agriculture and grazing land.

In some cases, different sources of environmental scarcity may interact, exacerbating the problem:

  • Resource capture: When a resource becomes relatively scarce — say, because of population growth — it often becomes more valuable. This increase in value may motivate powerful groups within society to take greater control of the resource, making it scarcer still. In this way, the demand-induced scarcity that accompanies an increase in population may lead to an increase in structural scarcity following efforts to monopolize the resource.
  • Ecological marginalization: When vital resources such as fertile land become scarce due to population growth and unequal access, impoverished people often move into ecologically-sensitive areas such as hillsides, tropical rain forests, and areas at risk of desertification. The rising population in these areas, combined with unsustainable land use practices, leads to environmental degradation and further scarcity.

The Philippines is one of many countries in which ecological marginalization has occurred. High rates of population growth — over 2 percent per year — have made cropland relatively scarce in the fertile lowlands, forcing many farmers to move into the less productive uplands. This migration was also encouraged by the fact that the land ownership in the lowlands was concentrated in the hands of a few elite landholders. As the lowland-to-upland migration proceeded, rising cultivation in the ecologically fragile uplands has led to erosion and ecological degradation, further shrinking the supply of available cropland.

These various forms of environmental scarcity can lead to a number of potentially destabilizing social effects, specifically:

  • lower agricultural production
  • economic stagnation or decline
  • migrations from areas of resource scarcity to areas of perceived opportunity
  • weakened governing institutions.

While the specific process varies from case to case, Pakistan's experience over the past two decades is illustrative. Rapid population growth, environmental degradation, and inefficient practices led to increasing scarcity of both cropland and water by the early 1990s. This scarcity, along with the spread of agricultural technologies that favored large landholders, helped concentrate valuable land in the hands of the country's economic and military elite (i.e., resource capture). As a result, while agricultural production and the national economy continued to grow, the benefits of this growth were not enjoyed equitably and income inequality has increased. Impoverished rural residents have flooded into cities looking for work, along with refugees from Afghanistan and returning workers from overseas. The influx of migrants overwhelmed municipal services in cities like Karachi, where population growth rates exceeded six percent in the mid-1990s. Squatter settlements were housing an estimated 41 percent of Karachi's population in the early 1990s, and frequent shortages water and electricity aggravated tensions between these and more established communities in the city.

Disruptive social effects such as these, in turn, can lead to violence under certain conditions. If group tensions in society are high, migration and relative deprivation can be a particularly volatile mix. In Pakistan, ethnic conflict became a serious urban problem as the influx of migrants altered the ethnic balance in the cities. The result has been long-running but diffuse urban violence that has simmered since the mid-1980s. The murder rate in Karachi, for example, more than doubled between 1990 and 1994, and attacks on municipal offices — particularly the electricity and water utilities — became common.

In sum, the connection between environmental scarcity and civil violence is indirect but important. Environmental scarcity is never the sole cause of conflict, but it is often an aggravating or contributing factor. Future efforts at conflict prevention and resolution should take the role that environmental scarcity plays into account, and appropriate interventions to prevent demand-, supply-, and structurally-induced scarcity should be pursued.

Bingham Kennedy, Jr. is associate editor at the Population Reference Bureau.