Whilst conflict arising from scarcity has been common throughout history, shortage of renewable resources in the next 50 years will probably occur with a speed, complexity and magnitude unprecedented in history. Whole countries can now be deforested in a few decades. Most of a region's topsoil can disappear in a generation. Acute depletion of the ozone layer may take only 20 years. Moreover, unlike non-renewables (including fossil fuels and iron ore), renewable resources are linked in highly complex systems. The overuse of water, soil or forests can lead to many unforeseen, simultaneous environmental crises. When a hillside is deforested, it disturbs the water cycle between the land and the atmosphere, while consequent erosion produces silt that can plug irrigations works and ruin coastal fisheries.
Future violence influenced by scarcities will not follow traditional patterns. Wars over natural resources have often been over non-renewable ones -- such as Japan's quest for oil and minerals in China and Southeast Asia before World War II. Today, many threatened renewable resources -- the atmosphere and the oceans -- are held in common. This makes it unlikely that they will be the object of straightforward clashes between nations. Also, we now understand that scarcities often produce insidious and cumulative social effects, such as large migrations and insurgency -- subnational conflicts that usually attract little attention in the industrialized world but can seriously affect the security of rich and poor countries alike.
The four resources most likely to help produce conflict are cropland, water, fish, and forests. Around the globe, the growth in grain productivity has slowed dramatically and the amount of food available per person has declined. This is due, in part, to increases in population. For people in many developing nations, access to productive cropland remains the key to survival and economic development.
Environmental concerns are one of many factors that may contribute to tension and potential regional or worldwide conflict. As a country exhausts its own resources, the population may become dissatisfied. In some instances, civil war may erupt as various factions fight over the limited remaining resources. In other cases, the population may be driven to emigrate to other countries to seek a better life. In either situation, the fabric of the country is destroyed and its ability to recover is severely compromised. Furthermore, tensions are created in the countries who support the newly arrived and often unwanted immigrants.
There are examples of interstate war over renewables such as cropland, forests, fresh water and fish. Examples are from Rwanda, South Africa, Pakistan, Gaza, Chiapas. These examples show that environmental scarcity can strengthen group identities based on ethnic, class or religious differences. If social and economic adaptation is unsuccessful, environmental scarcity constrains economic development and contributes to migrations. Migrations, ethnic tensions, economic disparities and weak institutions in turn often appear to be the main causes of violence.
Scarcities of renewable resources are already contributing to dislocation and violent conflicts in many parts of the Third World. Land scarcity in Bangladesh, produced in part by rapid population growth, has caused millions of people to migrate to India. This las led to brutal ethnic conflicts in the Indian states of Assam and Tripura. Expanding population and land degradation stimulated the growth of the Maoist Shining Path insurgency in the southern highlands of Peru. In the Middle East, severe shortages of ground water in the Jordan River basin reinforced the unequal distribution of water between Israelis and Palestinians. This hurts Palestinian farmers and deepens the economic crisis for West Bank Arabs. Ethiopia, the source of more than 80% of the Nile's flow, currently uses less than 1% of it, and is denied the right to dam the river's headwaters by its downstream neighbours the Sudan and Egypt. Egypt's former foreign minister and later UN Secretary General, Boutros Boutros-Ghali, prophesied that the next war in the region would be over the waters of the Nile.
Environmental damage costs China at least 15% of its gross national product. This burden is getting worse, mainly because of reduced crop yields due to water, soil and air pollution, the loss of farmland due to construction and erosion, and flooding and soil-nutrient loss caused by erosion and deforestation. As these factors combine with continued population growth, the Chinese government will be less able to manage the country's affairs. This will impede reforms and increase the chance of social disintegration. There could also be domestic strife because hugh numbers of people will move from China's ecologically devastated interior to its booming coastal zones. In the Philippines, a persistent insurgency is given extra impetus by the desperate poverty arising from degraded forests and soils in hilly areas of the interior. In South Africa, apartheid concentrated millions of blacks in some of the country's most ecologically sensitive territories. Wide swathes of these homelands have been stripped of trees for fuel and grazed won to bare dirt. The topsoil had eroded. This contributes to migration to cities and to the rapid growth of urban squatter settlements that are rife with violence.