Humans have long made use of deserts as places to live,
History and the
Bilma salt mines People have been living in deserts for millennia. Many, such as the
Bushmen in the
Kalahari, the
Aborigines in Australia and various tribes of
North American Indians, were originally
hunter-gatherers. They developed skills in the manufacture and use of weapons, animal tracking, finding water, foraging for edible plants and using the things they found in their natural environment to supply their everyday needs. Their self-sufficient skills and knowledge were passed down through the generations by word of mouth. Other cultures developed a
nomadic way of life as herders of
sheep,
goats,
cattle, camels,
yaks,
llamas or
reindeer. They travelled over large areas with their herds, moving to new pastures as seasonal and erratic rainfall encouraged new plant growth. They took with them their tents made of cloth or skins draped over poles and their diet included milk, blood and sometimes meat. The desert nomads were also traders. The Sahara is a very large expanse of land stretching from the Atlantic rim to Egypt.
Trade routes were developed linking the
Sahel in the south with the fertile Mediterranean region to the north and large numbers of camels were used to carry valuable goods across the desert interior. The
Tuareg were traders and the transported goods traditionally included
slaves,
ivory and
gold going northwards and salt going southwards.
Berbers with knowledge of the region were employed to guide the caravans between the various oases and
wells. Several million slaves may have been taken northwards across the Sahara between the 8th and 18th centuries. Traditional means of overland transport declined with the advent of motor vehicles, shipping and air freight, but
caravans still travel along routes between
Agadez and
Bilma and between
Timbuktu and
Taoudenni carrying salt from the interior to desert-edge communities. Round the rims of deserts, where more precipitation occurred and conditions were more suitable, some groups took to cultivating crops. This may have happened when
drought caused the death of herd animals, forcing herdsmen to turn to cultivation. With few inputs, they were at the mercy of the weather and may have lived at bare
subsistence level. The land they cultivated reduced the area available to nomadic herders, causing disputes over land. The semi-arid fringes of the desert have fragile soils which are at risk of erosion when exposed, as happened in the American
Dust Bowl in the 1930s. The grasses that held the soil in place were ploughed under, and a series of dry years caused crop failures, while enormous dust storms blew the topsoil away. Half a million Americans were forced to leave their land in this catastrophe. Similar damage is being done today to the semi-arid areas that rim deserts and about twelve million hectares of land are being turned to desert each year.
Desertification is caused by such factors as drought, climatic shifts, tillage for agriculture,
overgrazing and deforestation. Vegetation plays a major role in determining the composition of the soil. In many environments, the rate of erosion and run off increases dramatically with reduced vegetation cover.
Natural resource extraction , India Deserts contain substantial mineral resources, sometimes over their entire surface, giving them their characteristic colors. For example, the red of many sand deserts comes from
laterite minerals. Geological processes in a desert climate can concentrate
minerals into valuable deposits.
Leaching by
ground water can extract
ore minerals and redeposit them, according to the
water table, in concentrated form. Similarly, evaporation tends to concentrate minerals in desert lakes, creating dry lake beds or
playas rich in minerals. Evaporation can concentrate minerals as a variety of
evaporite deposits, including
gypsum,
sodium nitrate,
sodium chloride and
borates. Some major oilfields such as
Ghawar are found under the sands of Saudi Arabia. A field trial in the Sonoran Desert which exposed the roots of different species of tree to rhizobacteria and the
nitrogen fixing bacterium
Azospirillum brasilense with the aim of restoring degraded lands was only partially successful. Native Americans in the south western United States became agriculturalists around 600 AD when seeds and technologies became available from Mexico. They used terracing techniques and grew gardens beside seeps, in moist areas at the foot of dunes, near streams providing flood irrigation and in areas irrigated by extensive specially built canals. The
Hohokam tribe constructed over of large canals and maintained them for centuries, an impressive feat of engineering. They grew maize, beans, squash and peppers. A modern example of desert farming is the
Imperial Valley in California, which has high temperatures and average rainfall of just per year. The economy is heavily based on agriculture and the land is irrigated through a network of canals and pipelines sourced entirely from the
Colorado River via the
All-American Canal. The soil is deep and fertile, being part of the river's flood plains, and what would otherwise have been desert has been transformed into one of the most productive farming regions in California. Other water from the river is piped to urban communities but all this has been at the expense of the river, which below the extraction sites no longer has any above-ground flow during most of the year. Another problem of growing crops in this way is the build-up of salinity in the soil caused by the evaporation of river water. The greening of the desert remains an aspiration and was at one time viewed as a future means for increasing food production for the world's growing population. This prospect has proved false as it disregarded the environmental damage caused elsewhere by the diversion of water for desert project irrigation.
Solar energy capture proposed using the Saharan and
Arabian deserts to produce solar energy to power Europe and the Middle East. Deserts are increasingly seen as sources for
solar energy, partly due to low amounts of cloud cover. Many solar power plants
have been built in the
Mojave Desert such as the
Solar Energy Generating Systems and
Ivanpah Solar Power Facility. Large swaths of this desert are covered in mirrors. The potential for generating solar energy from the
Sahara Desert is huge, the highest found on the globe. Professor
David Faiman of
Ben-Gurion University has stated that the technology now exists to supply all of the world's electricity needs from 10% of the Sahara Desert. The
Negev Desert,
Israel, and the surrounding area, including the
Arava Valley, receive plenty of sunshine and are generally not
arable. This has resulted in the construction of many
solar plants. David Faiman has proposed that "giant" solar plants in the Negev could supply all of Israel's needs for electricity.
Warfare , 1942 The Arabs were probably the first organized force to conduct successful battles in the desert. By knowing back routes and the locations of oases and by utilizing camels, Muslim Arab forces were able to successfully overcome both Roman and Persian forces in the period 600 to 700 AD during the
expansion of the Islamic caliphate. Many centuries later, both world wars saw fighting in the desert. In the
First World War, the
Ottoman Turks were engaged with the British regular army in a campaign that spanned the Arabian Peninsula. The Turks were defeated by the British, who had the backing of irregular Arab forces that were seeking to
revolt against the Turks in the
Hejaz, made famous in
T.E. Lawrence's book
Seven Pillars of Wisdom. In the
Second World War, the
Western Desert Campaign began in
Italian Libya. Warfare in the desert offered great scope for tacticians to use the large open spaces without the distractions of casualties among civilian populations.
Tanks and
armoured vehicles were able to travel large distances unimpeded and
land mines were laid in large numbers. However, the size and harshness of the terrain meant that all supplies needed to be brought in from great distances. The victors in a battle would advance and their
supply chain would necessarily become longer, while the defeated army could retreat, regroup and resupply. For these reasons, the
front line moved back and forth through hundreds of kilometers as each side lost and regained momentum. Its most easterly point was at
El Alamein in
Egypt, where the Allies decisively defeated the Axis forces in 1942.
In culture arriving in a desert land with camels. 14th-century miniature from
Il milione. The desert is generally thought of as a barren and empty landscape. It has been portrayed by writers, film-makers, philosophers, artists and critics as a place of extremes, a
metaphor for anything from death, war or religion to the primitive past or the desolate future. There is an extensive literature on the subject of deserts. An early historical account is that of
Marco Polo (–1324), who travelled through Central Asia to China, crossing a number of deserts in his twenty four year trek. Some accounts give vivid descriptions of desert conditions, though often accounts of journeys across deserts are interwoven with reflection, as is the case in
Charles Montagu Doughty's major work,
Travels in Arabia Deserta (1888).
Antoine de Saint-Exupéry described both his flying and the desert in
Wind, Sand and Stars, and
Gertrude Bell travelled extensively in the Arabian desert in the early part of the 20th century, becoming an expert on the subject, writing books and advising the British government on dealing with the Arabs. Another woman explorer was
Freya Stark, who travelled alone in the Middle East, visiting Turkey,
Arabia,
Yemen,
Syria,
Persia and
Afghanistan, writing over twenty books on her experiences. The German naturalist
Uwe George spent several years living in deserts, recording his experiences and research in his 1976 book,
In the Deserts of this Earth. The American poet
Robert Frost expressed his bleak thoughts in his poem,
Desert Places (1933), which ends with the stanza "They cannot scare me with their empty spaces / Between stars – on stars where no human race is. / I have it in me so much nearer home / To scare myself with my own desert places." Saints associated with the desert include
Anthony the Great, also known as "Anthony of the Desert".
Pope Benedict XVI linked the metaphorical existence of "internal deserts" with physical and social deserts in his
homily inaugurating his
papacy: "The external deserts in the world are growing, because the internal deserts have become so vast". ==Deserts on other planets==