One quarter of the earth's land is threatened by desertification, according to estimates by the United Nations Environment Programme (UNEP). The livelihoods of over 1 billion people in more than 100 countries are also jeopardized by desertification, as farming and grazing land becomes less productive.
Desertification does not mean that deserts are steadily advancing or taking over neighbouring land. As defined by the United Nations Convention, desertification is a process of "land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities". Patches of degraded land may develop hundreds of kilometres from the nearest desert. But these patches can expand and join together, creating desert-like conditions. Desertification contributes to other environmental crises, such as the loss of biodiversity and global warming.
Drought often triggers desertification, but human activities are usually the most significant causes. Over-cultivation exhausts the soil. Overgrazing removes vegetation that prevents soil erosion. Trees that bind the soil together are cut for lumber or firewood for heating and cooking. Poorly drained irrigation turns crop-land salty, desertifying 500,000 hectares annually, about the same amount of soil that is newly irrigated each year.
Significant underlying causes include social and economic factors in developing countries, such as poverty, high population growth rates, unequal land distribution, refugee flows, modernization that disrupts traditional farming practices, and government policies that encourage the growing of cash crops on marginal land to pay off foreign debts.
Life on earth depends on the layer of soil that is the source of nutrients for plants, crops, forests, animals and people. Without it, ultimately none can survive. Although topsoil takes a long time to build up, if mistreated it can vanish in just a few seasons due to erosion by wind and water.
The economic problem
If properly cared for, drylands can contribute significantly to economic growth by serving as a base for agriculture, grazing and human habitation and activity. Yet these areas are vulnerable to drought and the results of unsustainable human activity.
Political and social problems
In addition to its negative economic and environmental impacts, desertification is partially responsible for population migration. Although no one knows for sure how many people have had to abandon their land when it turned to dust, it appears to be in the millions. One sixth of the population of Mali and Burkina Faso has already been uprooted because of desertification. It is also a factor in the immigration of Mexicans into the United States.
Poverty forces poor people to wring as much as possible from the land in order to feed, house and warm their families. Unfortunately, over-cultivation, deforestation and other unsustainable practices degrade the land, forcing people to look elsewhere to support themselves. Poor people are highly vulnerable to the effects of weather, as drought can cause famine, while good rains can cause precipitous drops in crop prices. Politically, the poor are also vulnerable, often relegated to the most marginal land.
Desertification has played a part in armed conflict in arid lands, having contributed to political instability, starvation and social breakdown in places such as Somalia.
To respond to the great Sahelian drought and famine of 1968-1974, in which over 200,000 people and millions of their animals died, the United Nations Sudano-Sahelian Office was established. It was originally set up to assist nine drought-prone countries in West Africa and was subsequently expanded to cover 22 countries south of the Sahara and north of the equator.
The United Nations first addressed the issue on a global scale at the United Nations Conference on Desertification, held in Nairobi in 1977. …