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Desertification is a type of
land degradation Land degradation is a process in which the value of the biophysical environment A biophysical environment is a life, biotic and Abiotic component, abiotic surrounding of an organism or population, and consequently includes the factors that ...
in
drylands Drylands are defined by a scarcity of water. Drylands are zones where precipitation In meteorology Meteorology is a branch of the (which include and ), with a major focus on . The study of meteorology dates back , though significant ...
in which biological productivity is lost due to natural processes or induced by human activities whereby fertile areas become increasingly arid. It is the spread of arid areas caused by a variety of factors, such as
climate change Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are more rapid than any known even ...
(particularly the current
global warming Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are more rapid than any known even ...
) and
overexploitation Overexploitation, also called overharvesting, refers to harvesting a renewable resource File:Global Vegetation.jpg, Global vegetation A renewable resource, also known as a flow resource, is a natural resource which will replenish to replace th ...

overexploitation
of
soil Soil is a mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, comp ...

soil
as a result of human activity. Throughout geological history, the development of deserts has occurred naturally. In recent times, the potential influences of human activity, improper land management, deforestation and climate change on desertification is the subject of many scientific investigations.


Definitions of words

As recently as 2005, considerable controversy existed over the proper definition of the term "desertification." Helmut Geist (2005) identified more than 100 formal definitions. The most widely acceptedGeist (2005)
p. 2
/ref> of these was that of the
Princeton University Princeton University is a private Private or privates may refer to: Music * "In Private "In Private" was the third single in a row to be a charting success for United Kingdom, British singer Dusty Springfield, after an absence of nearly tw ...

Princeton University
Dictionary which defined it as "the process of fertile land ''transforming into desert'' typically as a result of
deforestation deforestation in 1750-2004 (net loss) showing anthropogenic modification of remaining forest. File:MODIS (2020-08-01).jpg, 300px, Dry seasons, exacerbated by climate change, and the use of slash-and-burn methods for clearing tropical forest ...

deforestation
, drought or improper/inappropriate agriculture".
However, this original understanding that desertification involved the physical expansion of deserts has been rejected as the concept has evolved. Desertification has been defined in the text of the
United Nations Convention to Combat Desertification United may refer to: Places * United, Pennsylvania, an unincorporated community * United, West Virginia, an unincorporated community Arts and entertainment Films * United (2003 film), ''United'' (2003 film), a Norwegian film * United (2011 film) ...

United Nations Convention to Combat Desertification
(UNCCD) as "land degradation in arid, semi-arid and dry sub-humid regions resulting from various factors, including climatic variations and human activities." There exists also controversy around the sub-grouping of types of desertification, including, for example, the validity and usefulness of such terms as "man-made desert" and "non-pattern desert".


History

The world's most noted
deserts upright=1.5, alt=see caption, Sand dunes in the Rub' al Khali ("Empty quarter") in the United Arab Emirates">Rub'_al_Khali.html" ;"title="Sand dunes in the Rub' al Khali">Sand dunes in the Rub' al Khali ("Empty quarter") in the United Arab ...

deserts
have been formed by natural processes interacting over long intervals of time. During most of these times, deserts have grown and shrunk independent of human activities. Paleodeserts are large
sand sea An erg (also sand sea or dune sea, or sand sheet if it lacks dunes) is a broad, flat area of desert covered with wind-swept sand with little or no vegetative cover. The word is derived from the Arabic language, Arabic word ''ʿarq'' (), meaning ...
s now inactive because they are stabilized by vegetation, some extending beyond the present margins of core deserts, such as the
Sahara The Sahara (, ; ar, الصحراء الكبرى, ', 'the Greatest Desert') is a desert on the African continent Africa is the world's second-largest and second-most populous continent A continent is any of several large landma ...

Sahara
, the largest hot desert.United States Geological Survey
"Desertification"
1997
Historical evidence shows that the serious and extensive land deterioration occurring several centuries ago in arid regions had three epicenters: the Mediterranean, the Mesopotamian Valley, and the
Loess Plateau The Chinese Loess Plateau, or simply the Loess Plateau, is a plateau In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid ...
of China, where population was dense. The earliest known discussion of the topic arose soon after the
French colonization French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, a French language which originated in France, and its various dialects ** French people, a nation and ethnic group identified with F ...
of
West Africa West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 17 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Mauritania ...

West Africa
, when the Comité d'Etudes commissioned a study on ''desséchement progressif'' to explore the prehistoric expansion of the Sahara Desert.


Areas affected

Drylands Drylands are defined by a scarcity of water. Drylands are zones where precipitation In meteorology Meteorology is a branch of the (which include and ), with a major focus on . The study of meteorology dates back , though significant ...
occupy approximately 40–41% of Earth's land areaJohnson et al (2006)
p. 1
/ref> and are home to more than 2 billion people. It has been estimated that some 10–20% of drylands are already degraded, the total area affected by desertification being between 6 and 12 million square kilometres, that about 1–6% of the inhabitants of drylands live in desertified areas, and that a billion people are under threat from further desertification. As of 1998, the then-current degree of southward expansion of the Sahara was not well known, due to a lack of recent, measurable expansion of the desert into the Sahel at the time. The impact of global warming and human activities are presented in the Sahel. In this area the level of desertification is very high compared to other areas in the world. All areas situated in the eastern part of Africa (i.e. in the Sahel region) are characterized by a dry climate, hot temperatures, and low rainfall (300–750 mm rainfall per year). So, droughts are the rule in the Sahel region. Some studies have shown that Africa has lost approximately 650,000 km² of its productive agricultural land over the past 50 years; the propagation of desertification in this area is considerable. The climate of the Sahara has undergone enormous variations over the last few hundred thousand years, oscillating between wet (grassland) and dry (desert) every 20,000 years (a phenomenon believed to be caused by long-term changes in the
North African climate cycleNorth African climate cycles have a unique history that can be traced back millions of years. The cyclic climate pattern of the Sahara is characterized by significant shifts in the strength of the North African Monsoon. When the North African Monsoon ...
that alters the path of the
North African Monsoon North African climate cycles have a unique history that can be traced back millions of years. The cyclic climate Climate is the long-term pattern of weather Weather is the state of the atmosphere An atmosphere (from the greek word ...
, caused by an approximately 40000-year cycle in which the
axial tilt In , axial tilt, also known as obliquity, is the angle between an object's and its al axis, or, equivalently, the angle between its ial plane and . It differs from . At an obliquity of 0 degrees, the two axes point in the same direction; i.e., ...
of the earth changes between 22° and 24.5°). Some statistics have shown that, since 1900, the Sahara has expanded by 250 km to the south over a stretch of land from west to east 6,000 km long. The survey, done by the Research Institute for Development, had demonstrated that this means dryness is spreading fast in the Sahelian countries. 70% of the arid area has deteriorated and water resources have disappeared, leading to
soil degradation Soil retrogression and degradation are two regressive evolution processes associated with the loss of equilibrium of a stable A stable is a building in which livestock Livestock is commonly defined as domesticated Domestication is a sust ...
. The loss of
topsoil Topsoil is the upper, outermost layer of soil Soil is a mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements t ...
means that plants cannot take root firmly and can be uprooted by torrential water or strong winds. The United Nations Convention (UNC) says that about six million Sahelian citizens would have to give up the desertified zones of sub-Saharan Africa for North Africa and Europe between 1997 and 2020.
Lake Chad Lake Chad (french: links=no, Lac Tchad) is a historically large, shallow, endorheic lake Image:LakeBadwater crop.jpg, 230px, Death Valley, Spring 2005: ephemeral Lake Badwater in the flooded Badwater Basin An endorheic lake (also called a sink ...

Lake Chad
, located in the Sahel region, has been hit particularly hard by this phenomenon. The cause of the lake drying up is due to irrigation withdrawal and the annual rainfall dropping. The lake has shrunk by over 90% since 1987, displacing millions of inhabitants. Recent efforts have managed to make some progress toward its restoration, but it is still considered to be at risk of disappearing entirely. Another major area that is being impacted by desertification is the
Gobi Desert The Gobi Desert () is a large desert upright=1.5, alt=see caption, Sand dunes in the Rub' al Khali ("Empty quarter") in the United Arab Emirates">Rub'_al_Khali.html" ;"title="Sand dunes in the Rub' al Khali">Sand dunes in the Rub' al ...

Gobi Desert
. Currently, the Gobi desert is the fastest moving desert on Earth; according to some researchers, the Gobi Desert swallows up over of land annually. This has destroyed many villages in its path. Currently, photos show that the Gobi Desert has expanded to the point the entire nation of Croatia (about 4 million) could fit inside its area. This is causing a major problem for the people of China. They will soon have to deal with the desert as it creeps closer. Although the Gobi Desert itself is still a distance away from
Beijing Beijing ( ), as Peking ( ), is the of the . It is the world's , with over 21 million residents within an of 16,410.5 km2 (6336 sq. mi.). It is located in , and is governed as a under the direct administration of the with .Figures ...

Beijing
, reports from field studies state there are large sand dunes forming only 70 km (43.5 mi) outside the city.
South America South America is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continent ...

South America
is another area affected by desertification, as 25% of the land is classified as drylands. In
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country located mostly in the southern half of South America South America is a continent A continent is any of several large landmasse ...

Argentina
specifically, drylands represent more than half of the total land area, and desertification has the potential to disrupt the nation's food supply. In
Mongolia Mongolia (, mn, Монгол Улс, Mongol Uls, Mongolian script, Traditional Mongolian: '; literal translation, lit. "Mongol Nation" or "State of Mongolia") is a landlocked country in East Asia. It is bordered by Russia Mongolia–Russia ...

Mongolia
, around 90% of grassland is considered vulnerable to desertification by the UN. An estimated 13% of desertification in Mongolia is caused by natural factors, the rest is due to human influence particularly overgrazing and increased erosion of soils in cultivated areas. The area of Mongolian land covered by sand has increased by 8.7% over the last 40 years. These changes have accompanied the degradation of 70% of Mongolian pasture land. As well as overgrazing and climate change, the Mongolia government listed
forest fires A wildfire, bushfire, wildland fire or rural fire is an unplanned, unwanted, uncontrolled fire BBQ. Fire is the rapid oxidation of a material in the exothermic chemical process of combustion, releasing heat, light, and various reaction ...

forest fires
, blights, unsustainable
forestry Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forest A forest is an area of land dominated by tree In botany, a tree is a perennial plant with an elongated Plant stem, ste ...
and
mining Mining is the extraction of valuable mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occu ...

mining
activities as leading causes of desertification in the country. A more recent study also reports overgrazing as a leading cause of desertification as well as the transition from
sheep Sheep (''Ovis aries'') are quadrupedal, ruminant mammals typically kept as livestock. Like all ruminants, sheep are members of the order (biology), order Artiodactyla, the even-toed ungulates. Although the name ''sheep'' applies to many species ...

sheep
to
goat The domestic goat or simply goat (''Capra hircus'') is a domesticated species of typically kept as . It was from the (''C. aegagrus'') of and . The goat is a member of the animal family and the subfamily , meaning it is closely related ...

goat
farming in order to meet export demands for
cashmere wool Cashmere wool, usually simply known as cashmere, is a fiber Fiber or fibre (from la, fibra, links=no) is a natural Nature, in the broadest sense, is the natural, physical, material world or universe The universe ( la, univ ...
. Compared to sheep, goats do more damage to grazing lands by eating roots and flowers.


Effects


Sand and dust storms

There has been a 25% increase in global annual dust emissions between the late nineteenth century to present day. The increase of desertification has also increased the amount of loose sand and dust that the wind can pick up ultimately resulting in a storm. For example, dust storms in the Middle East “are becoming more frequent and intense in recent years” because “long-term reductions in rainfall promotlower
soil moisture Soil moisture is the water content 300px, Soil composition by Volume and Mass, by phase: air, water, void (pores filled with water or air), soil, and total. Water content or moisture content is the quantity of water Water is an Inorganic ...
and
vegetative cover Vegetation is an assemblage of plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular re ...
”.
Dust storms A dust storm, also called sandstorm, is a meteorological phenomenon common in arid A region is arid when it is characterized by a severe lack of available water, to the extent of hindering or preventing the growth and development of pl ...
can contribute to certain respiratory disorders such as pneumonia, skin irritations, asthma and many more. They can pollute open water, reduce the effectiveness of clean energy efforts, and halt most forms of transportation. Dust and sand storms can have a negative effect on the climate which can make desertification worse. Dust particles in the air scatter incoming radiation from the sun. The dust can provide momentary coverage for the ground temperature but the atmospheric temperature will increase. This can disform and shorten the life time of clouds which can result in less rainfall.


Food security

Global
food security Food security is the measure of the availability of food and individuals' Economic inequality, ability to access it. According to the United Nations' Committee on World Food Security, food security is defined as meaning that all people, at all t ...
is being threatened by desertification and
overpopulation Overpopulation or overabundance is a phenomenon that occurs when a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A speci ...
. The more the population grows, the more food that has to be grown. The agricultural business is being displaced from one country to another. For example, Europe on average imports over 50% of its food. Meanwhile, 44% of agricultural land is located in dry lands and it supplies 60% of the world's food production. Desertification is decreasing the amount of sustainable land for agricultural uses but demands are continuously growing. In the near future, the demands will overcome the supply. The violent
herder–farmer conflicts in Nigeria Nomadic conflict, Herder–farmer conflicts in Nigeria have mainly involved disputes over land resources between mostly Muslim Fulani herders and mostly Christian non-Fulani farmers across Nigeria and have been especially prominent in the Middle B ...
,
Sudan Sudan ( or ; ar, السودان, as-Sūdān), officially the Republic of the Sudan ( ar, جمهورية السودان, link=no, Jumhūriyyat as-Sūdān), is a country in Northeast Africa. It borders the countries of Central African Republ ...
,
Mali Mali (; ), officially the Republic of Mali (french: République du Mali; bm, ߡߊߟߌ ߞߊ ߝߊߛߏߖߊߡߊߣߊ, Mali ka Fasojamana, ff, 𞤈𞤫𞤲𞥆𞤣𞤢𞥄𞤲𞤣𞤭 𞤃𞤢𞥄𞤤𞤭, Renndaandi Maali, ar, جمهورية م ...
and other countries in the Sahel region have been exacerbated by climate change,
land degradation Land degradation is a process in which the value of the biophysical environment A biophysical environment is a life, biotic and Abiotic component, abiotic surrounding of an organism or population, and consequently includes the factors that ...
and
population growth Population growth is the increase in the number of people in a population Population typically refers the number of people in a single area whether it be a city or town, region, country, or the world. Governments typically quantify the size ...
.


Vegetation patterning

As the desertification takes place, the landscape may progress through different stages and continuously transform in appearance. On gradually sloped terrain, desertification can create increasingly larger empty spaces over a large strip of land, a phenomenon known as " brousse tigrée". A mathematical model of this phenomenon proposed by C. Klausmeier attributes this patterning to dynamics in plant-water interaction. One outcome of this observation suggests an optimal planting strategy for agriculture in arid environments.


Causes

The immediate cause is the loss of most vegetation. This is driven by a number of factors, alone or in combination, such as drought, climatic shifts, tillage for agriculture, overgrazing and
deforestation deforestation in 1750-2004 (net loss) showing anthropogenic modification of remaining forest. File:MODIS (2020-08-01).jpg, 300px, Dry seasons, exacerbated by climate change, and the use of slash-and-burn methods for clearing tropical forest ...
for fuel or construction materials. Vegetation plays a major role in determining the biological composition of the soil. Studies have shown that, in many environments, the rate of erosion and runoff decreases exponentially with increased vegetation cover. Unprotected, dry soil surfaces blow away with the wind or are washed away by flash floods, leaving infertile lower soil layers that bake in the sun and become an unproductive hardpan. Many scientists think that one of the most common causes is overgrazing, too much consumption of vegetation by cattle or other livestock. Scientists agree that the existence of a desert in the place where the
Sahara desert The Sahara (, ; ar, الصحراء الكبرى, ', 'the Greatest Desert') is a desert on the . With an area of , it is the largest hot in the world and the third largest desert overall, smaller only than the deserts of and the northern . ...

Sahara desert
is now located is due to a natural climate cycle; this cycle often causes a lack of water in the area from era to era. There is a suggestion that the last time that the Sahara was converted from savanna to desert it was partially due to overgrazing by the cattle of the local population. Overpopulation is one of the most dangerous factors contributing to desertification. Human populations are increasing at exponential rates, which leads to overgrazing, over-farming and deforestation, as previously acceptable techniques are becoming less sustainable. There are multiple reasons farmers use
intensive farming Intensive agriculture, also known as intensive farming (as opposed to extensive farming Extensive farming or extensive agriculture (as opposed to intensive farming) is an agricultural Agriculture is the science, art and practice of cultiv ...
as opposed to
extensive farming Extensive farming or extensive agriculture (as opposed to intensive farming Intensive agriculture, also known as intensive farming (as opposed to extensive farming Extensive farming or extensive agriculture (as opposed to intensive farming) i ...
but the main reason is to maximize yields. By increasing productivity, they require a lot more fertilizer, pesticides, and labor to upkeep machinery. This continuous use of the land rapidly depletes the nutrients of the soil causing desertification to spread.


Poverty

At least 90% of the inhabitants of drylands live in
developing countries A developing country is a sovereign state with a less developed Industrial sector, industrial base and a low Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no ...
, where they also suffer from poor economic and social conditions. This situation is exacerbated by land degradation because of the reduction in productivity, the precariousness of living conditions and the difficulty of access to resources and opportunities. A downward spiral is created in many underdeveloped countries by overgrazing, land exhaustion and
overdrafting Overdrafting is the process of extracting groundwater Groundwater is the water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms ...
of groundwater in many of the marginally productive world regions due to
overpopulation Overpopulation or overabundance is a phenomenon that occurs when a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A speci ...
pressures to exploit marginal drylands for farming. Decision-makers are understandably averse to invest in arid zones with low potential. This absence of investment contributes to the marginalisation of these zones. When unfavourable agro-climatic conditions are combined with an absence of infrastructure and access to markets, as well as poorly adapted production techniques and an underfed and undereducated population, most such zones are excluded from development.Cornet A., 2002. Desertification and its relationship to the environment and development: a problem that affects us all. In: Ministère des Affaires étrangères/adpf, Johannesburg. World Summit on Sustainable Development. 2002. What is at stake? The contribution of scientists to the debate: 91–125..
Desertification often causes rural lands to become unable to support the same sized populations that previously lived there. This results in mass out of rural areas and into urban areas (
urbanisation Urbanization (or urbanisation) refers to the population shift from rural In general, a rural area or a countryside is a geographic area that is located outside town A town is a . Towns are generally larger than s and smaller than , ...
), particularly in Africa. These migrations into the cities often cause large numbers of unemployed people, who end up living in
slums A slum is a highly populated Urban area, urban residential area consisting of densely packed housing units of weak build quality. The infrastructure in slums is often deteriorated or incomplete, and they are primarily inhabited by impoverished pe ...
. In
Mongolia Mongolia (, mn, Монгол Улс, Mongol Uls, Mongolian script, Traditional Mongolian: '; literal translation, lit. "Mongol Nation" or "State of Mongolia") is a landlocked country in East Asia. It is bordered by Russia Mongolia–Russia ...

Mongolia
the land is 90% fragile dry land, which causes many herders to migrate to the city for work. With very limited resources the herders that stay in the dry land graze very carefully in order to preserve the land. With the increasing population of Mongolia it is very difficult to stay a herder for long. The number of these environmental refugees grows every year, with projections for sub-Saharan Africa showing a probable increase from 14 million in 2010 to nearly 200 million by 2050. This presents a future crisis for the region, as neighboring nations do not always have the ability to support large populations of refugees. Agriculture is a main source of income for many desert communities. The increase in desertification in these regions has degraded the land to such an extent where people can no longer productively farm and make a profit. This has negatively impacted the economy and increased poverty rates. There is however increased global advocacy to combat desertification and restore affected lands such as the United Nations
Sustainable Development Goal 15 Sustainable Development Goal 15 (SDG 15 or Global Goal 15) is about "Life on land." One of the 17 Sustainable Development Goals The Sustainable Development Goals (SDGs) or Global Goals are a collection of 17 interlinked global goals designed ...

Sustainable Development Goal 15
amongst other countermeasures.


Countermeasures

Techniques and countermeasures exist for mitigating or reversing the effects of desertification, and some possess varying levels of difficulty. For some, there are numerous barriers to their implementation. Yet for others, the solution simply requires the exercise of human reason. One proposed barrier is that the costs of adopting sustainable agricultural practices sometimes exceed the benefits for individual farmers, even while they are socially and environmentally beneficial. Another issue is a lack of political will, and lack of funding to support
land reclamation Land reclamation, usually known as reclamation, and also known as land fill (not to be confused with a waste landfill), is the process of creating new Terrestrial ecoregion, land from oceans, list of seas, seas, Stream bed, riverbeds or lake be ...
and anti-desertification programs. Desertification is recognized as a major threat to
biodiversity Biodiversity is the biological variety and Genetic variability, variability of life, life on Earth. Biodiversity is a measure of variation at the Genetics, genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near ...

biodiversity
. Some countries have developed biodiversity action plans to counter its effects, particularly in relation to the protection of endangered
flora Flora is all the plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, ca ...

flora
and
fauna Fauna is all of the animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular r ...

fauna
.


Reforestation

Reforestation Reforestation (occasionally, reafforestation) is the natural or intentional restocking of existing forests and woodlands (forestation) that have been depleted, usually through deforestation, but also after clearcutting. Reforestation can be ...
gets at one of the root causes of desertification and is not just a treatment of the symptoms. Environmental organizations work in places where deforestation and desertification are contributing to extreme
poverty Poverty is the state of having little material possessions or income In microeconomics, income is the Consumption (economics), consumption and saving opportunity gained by an entity within a specified timeframe, which is generally expresse ...

poverty
. There they focus primarily on educating the local population about the dangers of deforestation and sometimes employ them to grow seedlings, which they transfer to severely deforested areas during the rainy season. The
Food and Agriculture Organization of the United Nations The Food and Agriculture Organization of the United Nations (FAO)french: Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is a specialized agency ...
launched the FAO Drylands Restoration Initiative in 2012 to draw together knowledge and experience on dryland restoration. In 2015, FAO published global guidelines for the restoration of degraded forests and landscapes in drylands, in collaboration with the Turkish Ministry of Forestry and Water Affairs and the Turkish Cooperation and Coordination Agency. The "
Green Wall of China The Great Green Wall, officially known as the Three-North Shelter Forest Program (), also known as the Three-North Shelterbelt Program, is a series of human-planted windbreaking forest strips (shelterbelts) in China, designed to hold back the des ...
" is a high-profile example of one method that has been finding success in this battle with desertification. This wall is a much larger-scale version of what American farmers did in the 1930s to stop the great Midwest dust bowl. This plan was proposed in the late 1970s, and has become a major ecological engineering project that is not predicted to end until the year 2055. According to Chinese reports, there have been nearly 66 billion trees planted in China's great green wall. The green wall of China has decreased desert land in China by an annual average of 1,980 square km. The frequency of sandstorms nationwide have fallen 20% due to the green wall. Due to the success that China has been finding in stopping the spread of desertification, plans are currently being made in Africa to start a "wall" along the borders of the Sahara desert as well to be financed by the United Nations Global Environment Facility trust. In 2007 the
African Union The African Union (AU) is a continental union A continental union is a regional organization which facilitates pan-continental integration. Continental unions vary from collaborative intergovernmental organization, intergovernmental organiza ...

African Union
started the Great Green Wall of Africa project in order to combat desertification in 20 countries. The wall is 8,000 km wide, stretching across the entire width of the continent and has 8 billion dollars in support of the project. The project has restored 36millionhectares of land, and by 2030 the initiative plans to restore a total of 100millionhectares. The Great Green Wall has created many job opportunities for the participating countries, with over 20,000 jobs created in Nigeria alone.


Soil restoration

Techniques focus on two aspects: provisioning of water, and fixation and hyper-fertilizing soil. Fixating the soil is often done through the use of shelter belts,
woodlot {{Unreferenced, date=February 2007 A woodlot is a parcel of a woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ''plurale tantum A ''plurale tantum'' (Latin ...
s and
windbreak A windbreak (shelterbelt) is a planting Sowing is the process of planting. An area or object that has had seeds planted in it will be described as a sowed area. Plants which are usually sown Among the major field crops, oats, wheat ...
s. Windbreaks are made from trees and bushes and are used to reduce
soil erosion Soil erosion is the displacement of the upper layer of soil File:Stagnogley.JPG, Surface-water-Gley soil, gley developed in glacial till, Northern Ireland. Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that togeth ...

soil erosion
and
evapotranspiration Evapotranspiration (ET) is the sum of water evaporation Evaporation is a type of that occurs on the of a as it changes into the gas phase. The surrounding gas must not be saturated with the evaporating substance. When the molecules of ...

evapotranspiration
. They were widely encouraged by development agencies from the middle of the 1980s in the
Sahel The Sahel (; ar, ساحل ' , "coast, shore") is the ecoclimatic and of in between the to the north and the to the south. Having a , it stretches across the south-central latitudes of between the Atlantic Ocean and the . The Sahel part o ...

Sahel
area of
Africa Africa is the world's second-largest and second-most populous continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', ...

Africa
. Some soils (for example,
clay Clay is a type of fine-grained natural soil Surface-water- gley developed in glacial till, Northern Ireland.">Northern_Ireland.html" ;"title="glacial till, Northern Ireland">glacial till, Northern Ireland. Soil is a mixture of organic m ...

clay
), due to lack of water can become consolidated rather than porous (as in the case of s). Some techniques as zaï or
tillage Tillage is the agricultural Agriculture is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching television 1958.jpg, Exercise trends, Increases in sedentary ...
are then used to still allow the planting of crops. Waffle gardens can also help as they can provide protection of the plants against wind/sandblasting, and increase the hours of shade falling on the plant. Another technique that is useful is contour trenching. This involves the digging of 150 m long, 1 m deep trenches in the soil. The trenches are made parallel to the height lines of the landscape, preventing the water from flowing within the trenches and causing erosion. Stone walls are placed around the trenches to prevent the trenches from closing up again. The method was invented by Peter Westerveld. Enriching of the soil and restoration of its fertility is often achieved by plants. Of these, which extract
nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

nitrogen
from the air and fix it in the soil,
succulents In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the An ...

succulents
(such as
Opuntia ''Opuntia'', commonly called prickly pear, is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circu ...

Opuntia
), and food crops/trees as
grain A grain is a small, hard, dry seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double albu ...

grain
s,
barley Barley (''Hordeum vulgare''), a member of the grass family Poaceae () or Gramineae () is a large and nearly ubiquitous family In human society, family (from la, familia) is a group of people related either by consanguinity (by recogn ...

barley
,
beans A bean is the seed of one of several genus, genera of the flowering plant family (biology), family Fabaceae, which are used as vegetables for human or animal food. They can be cooked in many different ways, including boiling, frying, and b ...

beans
and s are the most important.
Sand fence File:St. Clair, Dunedin, New Zealand, June 2009.jpg, A local landmark in Dunedin, New Zealand — the St. Clair Beach posts are the remains of a series of sandbreaks, originally linked by boards to catch the blown sand. A sand fence or sandbreak, si ...
s can also be used to control drifting of soil and sand erosion. Another way to restore soil fertility is through the use of nitrogen-rich fertilizer. Due to the higher cost of this fertilizer, many
smallholder A smallholding or smallholder is a small farm operating under a small-scale agriculture model. Definitions vary widely for what constitutes a smallholder or small-scale farm, including factors such as size, food production technique or technology ...
farmers are reluctant to use it, especially in areas where
subsistence farming Subsistence agriculture occurs when farmer A farmer is a person engaged in agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary ...
is common. Several nations, including India, Zambia, and Malawi have responded to this by implementing
subsidies A subsidy or government incentive is a form of financial aid or support extended to an economic sector (business, or individual) generally with the aim of promoting economic and social policy. Although commonly extended from the government, the ter ...
to help encourage adoption of this technique. Some research centres (such as Bel-Air Research Center IRD/ISRA/UCAD) are also experimenting with the inoculation of tree species with
mycorrhiza A mycorrhiza (from Ancient Greek, Greek μύκης ', "fungus", and ῥίζα ', "root"; pl. mycorrhizae, mycorrhiza or mycorrhizas) is a mutual symbiosis, symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role ...

mycorrhiza
in arid zones. The mycorrhiza are basically fungi attaching themselves to the roots of the plants. They hereby create a symbiotic relation with the trees, increasing the surface area of the tree's roots greatly (allowing the tree to gather much more nutrient from the soil). The
bioengineering Biological engineering, bioengineering, or bio-engineering is the application of principles of biology and the tools of engineering to create usable, tangible, economically-viable products. Biological engineering employs knowledge and experti ...
of soil microbes, particularly photosynthesizers, has also been suggested and theoretically modeled as a method to protect drylands. The aim would be to enhance the existing cooperative loops between soil microbes and vegetation.


Desert reclamation

As there are many different types of deserts, there are also different types of desert reclamation methodologies. An example for this is the salt flats in the
Rub' al Khali The Rub' al KhaliOther standardized transliterations include: / . The ' is the assimilated Arabic definite article An article is any member of a class of dedicated words that are used with noun phrases to mark the identifiability of the re ...
desert in
Saudi Arabia (''Shahada'') , national_anthem = "National Anthem of Saudi Arabia, " "National Anthem of Saudi Arabia" , image_map = Saudi Arabia (orthographic projection).svg , capital = Riyadh , coordinates ...

Saudi Arabia
. These salt flats are one of the most promising desert areas for seawater agriculture and could be revitalized without the use of freshwater or much energy.
Farmer-managed natural regeneration Farmer-managed natural regeneration (FMNR) is a low-cost, sustainable land restoration technique used to combat poverty and hunger amongst poor subsistence farmers in developing countries by increasing food production, food and timber production, an ...
(FMNR) is another technique that has produced successful results for desert reclamation. Since 1980, this method to reforest degraded landscape has been applied with some success in Niger. This simple and low-cost method has enabled farmers to regenerate some 30,000 square kilometers in Niger. The process involves enabling native sprouting tree growth through selective pruning of shrub shoots. The residue from pruned trees can be used to provide mulching for fields thus increasing soil water retention and reducing evaporation. Additionally, properly spaced and pruned trees can increase crop yields. The Humbo Assisted Regeneration Project which uses FMNR techniques in Ethiopia has received money from The World Bank's BioCarbon Fund, which supports projects that sequester or conserve carbon in forests or agricultural ecosystems.


Managed grazing

Restoring grasslands store CO2 from the air as plant material. Grazing livestock, usually not left to wander, eat the grass and minimize grass growth. A method proposed to restore grasslands uses fences with many small paddocks and moving herds from one paddock to another after a day or two in order to mimic natural grazers and allowing the grass to grow optimally. Proponents of managed grazing methods estimate that increasing this method could increase carbon content of the soils in the world's 3.5 billion hectares of agricultural grassland and offset nearly 12 years of CO2 emissions. One proponent of managed grazing,
Allan Savory Clifford Allan Redin Savory (born 15 September 1935) is a Zimbabwean ecologist, livestock farmer, and president and co-founder of the Savory Institute. He originated Holistic management (agriculture), a systems thinking approach to Resource man ...

Allan Savory
, as part of
holistic management Holistic Management (from ''holos'', a Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. ...
, claims that keeping livestock tightly packed on smaller plots of land, meanwhile rotating them to other small plots of land will reverse desertification; range scientists have however not been able to experimentally confirm his claims.


See also

*
Aridification Aridification is the process of a region becoming increasingly arid A region is arid when it is characterized by a severe lack of available water, to the extent of hindering or preventing the growth and development Development or developing ma ...
*
Deforestation deforestation in 1750-2004 (net loss) showing anthropogenic modification of remaining forest. File:MODIS (2020-08-01).jpg, 300px, Dry seasons, exacerbated by climate change, and the use of slash-and-burn methods for clearing tropical forest ...

Deforestation
*
Detention basin A detention basin or retarding basin is an excavated area installed on, or adjacent to, tributaries of river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some case ...
*
Soil retrogression and degradationSoil retrogression and degradation are two regressive evolution processes associated with the loss of equilibrium of a stable A stable is a building in which livestock Livestock is commonly defined as domesticated Domestication is a susta ...
*
Wadi Wadi ( ar, وَادِي, wādī), alternatively ''wād'' ( ar, وَاد), North African Arabic Oued, is the Arabic term traditionally referring to a valley A valley is an elongated low area often running between hills or mountains, ...

Wadi
*
Water scarcity Water scarcity (water stress or water crisis) is the lack of fresh water resources to meet the standard water demand. Humanity is facing a water crisis, due to unequal distribution (exacerbated by climate change Climate change inclu ...

Water scarcity
Mitigation: *
Desert greening Desert greening is the process of man-made reclamation of deserts for ecological reasons (biodiversity), farming and forestry, but also for reclamation of natural water systems and other ecological systems that support life. The term "desert gre ...
*
Ecological engineering Ecological engineering uses ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecolog ...
* Oasification Other related portals:


References


Bibliography

* * Barbault R., Cornet A., Jouzel J., Mégie G., Sachs I., Weber J. (2002). Johannesburg. World Summit on Sustainable Development. 2002. What is at stake? The contribution of scientists to the debate. Ministère des Affaires étrangères/adpf. * * Batterbury, S.P.J. & A.Warren (2001
Desertification
in N. Smelser & P. Baltes (eds.) International Encyclopædia of the Social and Behavioral Sciences. Elsevier Press. pp. 3526–3529 * * * * * Holtz, Uwe (2007). ''Implementing the United Nations Convention to Combat Desertification from a parliamentary point of view – Critical assessment and challenges ahead''. Online a

* Holtz, Uwe (2013). ''Role of parliamentarians in the implementation process of the UN Convention to Combat Desertification. A guide to Parliamentary Action'', ed. Secretariat of the UNCCD, Bonn . Online a

* * Lucke, Bernhard (2007): Demise of the Decapolis. Past and Present Desertification in the Context of Soil Development, Land Use, and Climate. Online a

* *
Millennium Ecosystem Assessment The Millennium Ecosystem Assessment (MA) is a major assessment of the human impact on the environment, called for by the United Nations Secretary-General Kofi Annan in 2000, launched in 2001 and published in 2005 with more than $14 million of gr ...
(2005
''Desertification Synthesis Report''
* Moseley, W.G. and E. Jerme 2010. “Desertification.” In: Warf, B. (ed). Encyclopedia of Geography. Sage Publications. Volume 2, pp. 715–719. * * * Reynolds, James F., and D. Mark Stafford Smith (ed.) (2002) ''Global Desertification – Do Humans Cause Deserts?'' Dahlem Workshop Report 88,
Berlin Berlin (; ) is the Capital city, capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3,769,495 inhabitants, as of 31 December 2019 makes it the List of cities in the European Union by ...

Berlin
: Dahlem University Press * * UNCCD (1994
United Nations Convention to Combat Desertification
* The End of Eden a 90-minute documentary by South African filmmaker
Rick Lomba Rick Lomba (1950–1994) was a South African documentary filmmaker, environmentalist and Carte Blanche cameraman. He was also a lobbyist at the European Parliament and the US Congress against their cattle policies in Botswana. His main concern ...
in 1984 on African desertification ;Attribution *


External links


Official website of the Secretariat
of the
United Nations Convention to Combat Desertification United may refer to: Places * United, Pennsylvania, an unincorporated community * United, West Virginia, an unincorporated community Arts and entertainment Films * United (2003 film), ''United'' (2003 film), a Norwegian film * United (2011 film) ...

United Nations Convention to Combat Desertification
(UNCCD) *
Procedural history and related documents
on the UNCCD, from the
United Nations Audiovisual Library of International Law The United Nations Audiovisual Library of International Law is a free online international law research and training tool. It was created and is maintained by the Codification Division of the United Nations Office of Legal Affairs as a part of its m ...

Official website
of Action Against Desertification, a
United Nations The United Nations (UN) is an intergovernmental organization aiming to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and be a centre for harm ...

United Nations
Food and Agriculture Organization The Food and Agriculture Organization of the United Nations (FAO)french: Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is a specialized agency ...
initiative of the
African, Caribbean and Pacific Group of States The Organisation of African, Caribbean and Pacific States (OACPS) is a group of countries A country is a distinct territorial body or political entity A polity is an identifiable political entity—any group of people who have a colle ...

''Global Deserts Outlook''
(2006), thematic assessment report in the
Global Environment Outlook Global Environment Outlook (GEO) is a series of reports on the environment (biophysical), environment issued periodically by the United Nations Environment Programme (UNEP). The GEO project was initiated in response to the Environmental reports, ...
(GEO) series of the
United Nations Environment Program The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong Maurice Frederick Strong, (April 29, 1929 – November 27, 20 ...
(UNEP). *
French Scientific Committee on Desertification (CSFD)
{{Doomsday Environmental soil science Human overpopulation Paleoclimatology