Of every 100 people residing in the world only five inhabit the deserts. However, hot and polar deserts occupy over 30% of the land surface. Since there is little vegetation, they cannot support many people.
World''s existing deserts can be classified into five types according to climate. They are subtropical, cool coastal, rain-shadow, interior continental and polar desert. The first four of these have hot summer and cold winter. Here water is deficient throughout the year because evaporation exceeds the annual rainfall. In polar deserts, summer is generally cold and winter is bitterly cold. Since water is present in a frozen state for most of the year, it is not readily available to plants and animals.
In deserts, high temperatures and low humidity during the day may be followed by comparatively cold nights even in subtropical deserts. Here long periods of drought are broken by torrential rainfall and flooding.
Desert rainfall is seasonal. It is erratic and the total annual precipitation varies from one year to another. In most deserts, dunes cover less than half the land surface. They occur in endless variation.
During the last century, deserts have been expanding at an alarming rate. Southern Sahara, Somalia and the border of the Thar Desert of India as well as Pakistan were green and fertile within living memory. Now they are dry and barren. This is due to unwise human activities, especially massive deforestation.
Desert expansion is one of the outcomes of the world''s present population. It is taking place at a time when half the people in the world are suffering from malnutrition.
Since time immemorial, man has been reducing the productive capacity of arid lands by overexploiting them. It has become necessary to fight against deserts not only to save human beings but also to reduce their sufferings. Not only this, it must be fought to improve the quality of life for future generation.
Much land has been changed into desert during the past century as would suffice to provide food for the world''s entire human population. Most of them are unsuitable for agriculture and remain the preserve of nomadic who move about the country regularly to exploit rain filled wells and pastures for their camels, sheep and goats. Actually, it is indispensable to fight against deserts for feeding the increasing number of mouths to be fed each year.
To combat desertification, the United Nations designated 2006 as the International Year of Deserts and Desertification (IYDD). The aim of the IYDD was to raise international awareness of the issue and to highlight the plight of the people in those countries experiencing serious drought or desertification.
Held to celebrate this international year, the symposiums featured lectures and panel discussions about deserts. They provided an opportunity for the networking of international research and activities within the purview of dry lands for discussion and future direction. Apart from this, there was also a review of research findings produced to date. However, there has been no substantial progress in reducing desertification.
The most intended riches of deserts are the deposits of oil and minerals that lie underground. Moreover, tropical deserts possess an inexhaustible supply of solar energy, which can provide power for industry.
A manufacturing industry uses less water per head of population than does agriculture. A day may even come when enlightened industries expand in desert countries.
In the pursuit of modern society, people often get tired of crowded cities and wish for the wide open spaces and solitude which are available in desert. Since air transport places the world at our doorsteps, one day the tourist value of the deserts may exceed the value of their mineral wealth. When that time comes, the endeavors of scientists and conservationists to preserve the desert countryside, with its extraordinary variety of plants and animals, will be worthwhile. However, desertificatiuld be controlled in time, otherwise it will augment hunger problem in the world, especially in developing and least developed countries.
Today, technological development has changed the face of the earth. It has led to increases in the possession of material goods and to the squandering of the world''s resources. This is why modern technology can be used to harness deserts for the benefit of human beings without causing serious damage to the environments. In this context, sand dunes can be stabilized and sown with grasses or planted with trees. Undoubtedly, this procedure is complicated and expensive. In addition, it requires large number of men and machines. However, its consequence will be useful and fruitful. Actually, many desert countries should learn lessons from Israel whose area of deserts is decreasing through the use of technology.