Natural Hazards: Causes and Effects - Disaster Management Center ...

Chapter 8
Desertification
Introduction and Definition
Although deserts are not without life, they can be viewed as areas with extremely limited
agricultural potential. Deserts occur in a variety of types, hot and cold, stony and sandy, but all
are characterized by rainfall deficiencies so marked that cultivation or stock-rearing are possible
only with special adaptations, as, for example, by the development of irrigation. Desertification,
as the extension or intensification of desert conditions, involves a decline in the productivity of
the land. Desertification, especially in developing countries, worsens conditions of poverty,
brings malnutrition and disease, erodes the basis of the national economy and then brings
deterioration of social services already hampered by remoteness and lack of funds. All this
affects the ability of dryland communities to respond to succeeding droughts, each of which
would then tend to advance further the deterioration of living standards, which represents the
human aspect of desertification.
Desertification, as part of the cycle of agriculturally good and bad years, is a slow-onset
disaster. Signs of its approach are in evidence well before the situation becomes catastrophic.
Desertification arises from the interaction between a difficult, unreliable and sensitive dryland
environment and the human use and occupation of it in an effort to make a living. For this
reason people who live in susceptible areas must learn how to live and work in harmony with
the constant threat of desertification.
If desertification were allowed to develop uncontrolled, almost the entire population of the
earth’s drylands could be said to face eventual risk. These drylands contain between 600 and
700 million people, and in terms of broad areas and livelihood systems their numbers are as
shown in Table 8.1. 1
The number of people immediately threatened, their general location and livelihood systems,
are shown in Table 8.2. 2 Of the 78 million people threatened, about a third may be in a position,
because of high income or other advantages, to avoid the worst consequences of
desertification. This still leaves about 50 million people who are immediately menaced through
the destruction of their livelihoods. These people face the grim prospect of uprooting
themselves from everything familiar and migrating to other areas frequently ill-equipped to
receive them.
Historical Examples
The Sahara
In Arabic sahra means “desert.” Sahara is plural. Indeed, the Sahara is not one but many
deserts. It contains half the desert surface of the world.
In the past 65 million years the borders of the Sahara have expanded and retreated many times.
Oak and cedar trees once grew in the Saharan highlands, and rock paintings portray abundant
wildlife. But about 3000 B.C. the current drying trend began setting in, and humans, relative
newcomers to north Africa, had to contend with desertification of the worst degree.