Scientific American, February 1993
by Thomas Homer-Dixon, Jeffrey H. Boutwell and George W. Rathjens
Growing scarcities of renewable resources can contribute to social instability and civil strife.
Within the next 50 years, the human population is likely to exceed nine billion, and global economic output may quintuple. Largely as a result of these two trends, scarcities of renewable resources may increase sharply. The total area of highly productive agricultural land will drop, as will the extent of forests and the number of species they sustain. Future generations will also experience the ongoing depletion and degradation of aquifers, rivers and other bodies of water, the decline of fisheries, further stratospheric ozone loss and, perhaps, significant climatic change.
As such environmental problems become more severe, they may precipitate civil or international strife. Some concerned scientists have warned of this prospect for several decades, but the debate has been constrained by lack of carefully compiled evidence. To address this shortfall of data, we assembled a team of 30 researchers to examine a set of specific cases. In studies commissioned by the University of Toronto and the American Academy of Arts and Sciences, these experts reported their initial findings.
The evidence that they gathered points to a disturbing conclusion: scarcities of renewable resources are already contributing to violent conflicts in many parts of the developing world. These conflicts may foreshadow a surge of similar violence in coming decades, particularly in poor countries where shortages of water, forests and, especially, fertile land, coupled with rapidly expanding populations, already cause great hardship.
Before we discuss the findings, it is important to note that the environment is but one variable in a series of political, economic and social factors that can bring about turmoil. Indeed, some skeptics claim that scarcities of renewable resources are merely a minor variable that sometimes links existing political and economic factors to subsequent social conflict.
The evidence we have assembled supports a different view [see illustration on page 40]. Such scarcity can be an important force behind changes in the politics and economics governing resource use. It can cause powerful actors to strengthen, in their favor, an inequitable distribution of resources. In addition, ecosystem vulnerability often contributes significantly to shortages of renewable resources. This vulnerability is, in part, a physical given: the depth of upland soils in the tropics, for example, is not a function of human social institutions or behavior. And finally, in many parts of the world, environmental degradation seems to have passed a threshold of irreversibility. In these situations, even if enlightened social change removes the original political, economic and cultural causes of the degradation, it may continue to contribute to social disruption. In other words, once irreversible, environmental degradation becomes an independent variable.
Skeptics often use a different argument. They state that conflict arising from resource scarcity is not particularly interesting, because it has been common throughout human history. We maintain, though, that renewable resource scarcities of the next 50 years will probably occur with a speed, complexity and magnitude unprecedented in history. Entire countries can now be deforested in a few decades, most of a region’s topsoil can disappear in a generation, and acute ozone depletion may take place in as few as 20 years.
Unlike nonrenewable resources-including fossil fuels and iron ore-renewable resources are linked in highly complex, interdependent systems with many nonlinear and feedback relations. The over-extraction of one resource can lead to multiple, unanticipated environmental problems and sudden scarcities when the system passes critical thresholds.
Our research suggests that the social and political turbulence set in motion by changing environmental conditions will not follow the commonly perceived pattern of scarcity conflicts. There are many examples in the past of one group or nation trying to seize the resources of another. For instance, during World War II, Japan sought to secure oil, minerals and other resources in China and Southeast Asia.
Currently, however, many threatened renewable resources are held in common -including the atmosphere and the oceans -which makes them unlikely to be the object of straightforward clashes. In addition, we have come to understand that scarcities of renewable resources often produce insidious and cumulative social effects, such as population displacement and economic disruption. These events can, in turn, lead to clashes between ethnic groups as well as to civil strife and insurgency. Although such conflicts may not be as conspicuous or dramatic as wars over scarce resources, they may have serious repercussions for the security interests of the developed and the developing worlds.
Human actions bring about scarcities of renewable resources in three principal ways. First, people can reduce the quantity or degrade the quality of these resources faster than they are renewed. This phenomenon is often referred to as the consumption of the resource’s “capital”: the capital generates “income” that can be tapped for human consumption. A sustainable economy can therefore be defined as one that leaves the capital intact and undamaged so that future generations can enjoy undiminished income. Thus, if topsoil creation in a region of farmland is 0.25 millimeter per year, then average soil loss should not exceed that amount.
The second source of scarcity is population growth. Over time, for instance, a given flow of water might have to be divided among a greater number of people. The final cause is change in the distribution of a resource within a society. Such a shift can concentrate supply in the hands of a few, subjecting the rest to extreme scarcity.
THOMAS F. HOMER-DIXON, JEFFREY H. BOUTWELL and GEORGE W. RATHJENS are co-directors of the project on Environmental Change and Acute Conflict, which is jointly sponsored by the University of Toronto and the American Academy of Arts and Sciences. Homer-Dixon received his Ph.D. in political science from the Massachusetts Institute of Technology in 1989 and is now coordinator of the Peace and Conflict Studies Program at the University of Toronto. Boutwell, who also received his Ph.D. from M.I .T., is associate executive officer and program director of International Security Studies at the American Academy of Arts and Sciences. Rathjens earned his doctorate in chemistry at the University of California, Berkeley, and is currently professor of political science at M. I .T.
