Desertification: An Introduction
What is desertification and what causes it?
The world’s greatest deserts were created over long periods of time by natural processes. Deserts
grow and shrink as climates dry and wet. But it is the edges of deserts that we are worried about. These
transition zones between a desert and a more wet environment are very fragile. At the edge of a desert,
you may find plants that feed animals and protect soil from wind erosion. Because areas on the margin
of deserts host more plant and animal life, humans have long used these areas for animal grazing.
The margins of deserts, however, can only take so much animal grazing. Livestock such as sheep
and goats that the humans raise pound the soil with their hooves. This increases erosion by water and
even wind. People also collect firewood, reducing the number of plants that protect the soil. This nighttime satellite image, courtesy of NASA, shows fires as red dots in the Sahel of North Africa. [The White
dots are other sources light at night]
This “degradation” of land is called desertification. Degradation is a term in geography that
means to lower the surface by erosion. Desertification is the invasion of desert into non-desert lands.
Desertification does not occur in a straight line. Deserts can advance in odd ways, and areas far
from natural deserts can degrade to rock or sand. Often the process of desertification is too far advanced
to prevent it by the time someone notices the problem.
Droughts do not cause desertification, but they can work together with humans to worsen the
problem It is natural that some areas will not receive rain in some years. Well-managed lands can
recover from drought when rains return. However, the increase of populations and grazing on marginal
land does increase desertification. In 1973, the drought and the land-use practices in the Sahel of West
Africa resulted in the deaths of 100,000 people and 12 million cattle. It was the combination of too
many people living in a marginal area, drought, and overgrazing that resulted in this disaster.
What can be done about desertification?
Global monitoring using satellites has begun to provide information about desertification.
Satellite images of the same locations taken over a period of time show changes in the land.
Individuals and governments can help to protect their lands. Sand dunes can be covered with
large stones or oil to keep the sand from moving. Sand fences are used in the Middle East in the same
manner that snow fences are used in other parts of the world. Plants can also be irrigated and grown at
the base of sand dunes. This helps stop erosion.
Oases and farmlands can be protected the planting tree fences or grass belts. A “Green Wall” of
trees (more than 5,700 kilometers long) is actually being constructed in China to protect sandy areas
created by human activity.
This space shuttle
picture shows the boundary
between Israel's Negev Desert
and Egypt's Sinai Peninsula.
The lighter color of the Sinai
is from more animal grazing
on the Egypt side. The darker
color of the Negev Desert is
from more plants growing.
The map is courtesy of the
CIA and the shuttle
image is courtesy of NASA.
More efficient use of
water resources and the
control of salt in the soil are
helping to improve the land.
New ways are being
investigated for collecting
seasonal run-off from nearby
highlands and rainwater.
Researchers also study new
ways of irrigation and crop
rotation. Ways to prevent
desertification can come only
from the wise use of
geographic and scientific
information.