April 29, 2019 Soil Degradation Written by Sara Slavikova
Causes and effects of desertification
The word ‘desertification’ may seem like a word

depicting very distant and abstract environmental problem that most of us do not consider being important in our daily lives. But we couldn’t be more mistaken, for desertification is slowly creeping up into our lives and has the power to change everything.

Higher food prices, water availability, violent conflicts for land, migration, increasing poverty, pollution from wind-blown dust particles coming from distant lands, could be the outcomes of desertification if we let it consume more of our planet.

The loss of fertile land to desertification has brought an end to many majestic civilizations throughout the human history. For example, the destruction of the native tropical forest in the Indus Valley opened up a pathway for the desert to claim more and more land, leading to the doom of the Harrapan Civilization. Sadly, the very same process continues to threaten the existence of at least 1.5 billion people (mainly from developing countries) until the present day [1].

One third of the land surface on Earth has fallen victim to desertification and according to the estimates, another 12 million hectares (approx. 30 million acres) more turn into barren deserts every year [1,2]. For comparison, it is the same size like the area of New York State turning in desert just within a year [3].

Do we have so much free land available that we do not need to be concerned about this?

Let’s have a look where it all started and what are the consequences.

 

What is the process of desertification?

Desertification is a process by which fertile land is transformed into desert as it becomes progressively drier and unable to support any plant growth for food production. Unlike the natural desert ecosystem with well-adapted species still inhabiting the area, desertified lands are often devoid of natural life without a healthy ecosystem in place that would perform life-supporting services, like new soil formation and nutrient cycling. This is what makes the reversal of the process extremely difficult.

The official definition by the United Nations Convention to Combat Desertification (UNCCD) that has been widely used since it’s formulation in 1994 is: “desertification is land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic fluctuations and human activities.” UNCCD also highlights that it is important to note that desertification is not a natural process of deserts expanding to new regions, it is a form of land degradation caused primarily by human activity in vulnerable areas. 

The loss of land to desertification has major impact on many places on our planet today and is expected to affect humanity even more in the future as population numbers will grow bigger and the availability of natural resources will decline.

Where is desertification happening the most?

Pretty much every continent has some dryland area that is currently threatened by desertification if no immediate preventative measures will be taken. You may be even able to identify the most vulnerable areas yourself, as they include grasslands, steppes, prairies, savannahs, shrublands and woodlands.

Countries affected by desertification do not have to be located only in hot regions of the world because it is the local climate and land use that shape the health of the land. For example, up to 50 percent of the Canadian Prairies spreading over Alberta, Saskatchewan and Manitoba are likely to battle with some of the negative effects of desertification in the upcoming years.

And globally, the risk of losing more land is getting higher with increasing summer temperatures and less frequent and erratic rain patterns we are experiencing in the last years.

However, the main reason why desertification goes widely unnoticed is that 90 percent of people affected by this phenomenon currently live in developing countries, mainly in Africa and Asia, and belong to the world’s poorest [4].

According to the current estimates, approximately 37 percent of the land in Africa is on the edge of turning irreversibly into desert, and 33 percent of Asia faces the same risk as well [5].

But how does such a serious form of land degradation happen and how come we let it advance so far?

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What causes desertification?

Lands turn to desert due to a number of reasons, but much of the desertification that is occurring around the world today is caused by human activity on lands that are extremely vulnerable to overexploitation and improper agricultural methods.

The following are some of the primary causes of desertification in our world.

#1 Overgrazing

Overgrazing and desertification have been always closely linked together.

In dry regions, grass and other small vegetation is necessary to keep the soil in place to prevent erosion and further damage to the soil. However, it is the paradox of life that especially in these vulnerable regions, animal herding is often the only livelihood people can have and there are no restrictions in place that would regulate the maximum number of animals for a given space.

When people gather and keep too many animals in one area, grasses start dying because their roots are often weakened by animals constantly stepping on them and plucking out newly re-growing parts before plants have time to grow resistant enough and to multiply.

After some time, no vegetation remains to prevent soil from blowing or washing away. So, people move the livestock to another piece of land where the process repeats. If this occurs long enough, it leads to extensive desertification.

Overgrazing in Mongolian steppe

There have been numerous cases when overgrazed areas of land became severely damaged.

Scientists have, for example, confirmed that overgrazing is the primary reason why around 70 percent of the once pasture rich Mongolian steppe is slowly overtaken by the Gobi Desert now.

The situation in Mongolia is alarming, particularly because this land degradation has taken place just recently. Since 1990s, when the lack of jobs due to the breakup of the Soviet Union forced people to rear livestock as their only possibility to earn money [6].

Similar scenario has happened even with the Bedouins grazing their herds freely over the fragile steppe in Syria. For 50 years, large herds of livestock grazed over the Syrian steppe until the effects couldn’t be overlooked anymore. Overgrazing has become a problem that has escalated into an ecological and agricultural collapse in the country.

#2 Unsustainable agriculture techniques

The world’s drylands cover approximately 40 percent of the total land mass. They are home to more than 2 billion people, so it is clear that many of these areas are farmed, even though they are very fragile and can easily turn barren.

Through inconsiderate farming methods like heavy tilling, planting of unsuitable crops and leaving soils exposed to wind and rain erosion, farmers only speed up the process of desertification in exchange for poor quality crops with low economic value. Besides, while preparing the soil for sowing, natural vegetation that holds the brittle soil in place is removed, letting the last bits of the productive soil layer fully wear away in just a few short seasons.

Another common problem of the crop cultivation in vulnerable areas is the employment of improper irrigation methods, such as canal irrigation. These irrigation methods often lead to a buildup of salt in soils. Increased salinity happens because irrigation water mobilizes naturally occurring salt in these soils. Additionally, artificially added water also rises otherwise low groundwater level which in turn dissolves even more salts [7].

Salt buildup on cultivated lands, then, makes it difficult for crops and other plants to grow, further exacerbating degradation of these lands.

A sad example of the destructive power of such a mismanagement is the drying out of the Aral Sea. The Aral Sea used to be the world’s fourth largest saline lake until 1960s, when the Soviet government diverted the Amu Darya and Syr Darya rivers, which have been feeding the lake with fresh water.

Why would they do that?

Because of ambitious cotton farming projects in the dry Aral Sea basin that needed irrigation.

Cotton farming in the desert combined with poorly build irrigation channels, from where lot of water simply evaporated, decreased the size of the Aral Sea by 90 (!) percent [8]. And the land of the dry lake basin became a saline desert where nothing grows on its own.

Local communities that used to live by the lake rich with fish and biodiversity, live now only amidst dust, pesticide pollution and scorching heat. They are the ones who have seen the ugly face of desertification slowly reaching their doorstep, and they are the ones who are also witnessing how fast sand and dust consume even more land every year.

#3 Deforestation

In November 2016, Guardian published an article with the title “We have been almost buried: the Sudanese villages being swallowed by sand.” The article goes on describing the struggles of villages in Sudan’s River Nile State that have succumbed to desertification after years of extensive deforestation and worsening droughts. Villages that were once surrounded by forests so dense that you could get lost in them, are now disappearing under the sand. 

Deforestation is one of the leading human causes of desertification. Forests are being cut down at much larger scale than ever before, to be used as fuel, to provide products we use in our daily life, or to simply create more space for agriculture to sustain growing human population.

When the trees and other vegetation in an area are gone, there are no roots that would hold soils in place, there is no canopy that would shield the ground from the direct rainfall or from the sun’s heat. The bare soil then easier dries out and turns to dust, which can be blown and washed away in a single storm.

Dead trees in a desert

Once the soil is degraded and the precious nutrients are lost, only infertile and lifeless swaths of land are left behind. And what’s more, without trees, even the local climate becomes drier due to the lack of water evapotranspiration from tree canopy, which reduces cloud formation in the region and results in less rain.

After all, history tends to repeat itself, so perhaps the story of the Maya could serve as a warning sign for us. According to model simulations ran by the NASA Goddard Institute for Space Studies, the end of the Mayan empire probably happened due to prolonged droughts caused by cutting down the rainforest to expand their cities and plant crops to feed their growing population [9].

#4 Unsustainable water management

Drylands, the most susceptible areas to desertification, are characterized by a scarcity of water during certain periods of the year. This means that the original ecosystem of these lands is well-adapted to withstand dry seasons during which plants enter so called summer dormancy, a temporary cessation of growth, in order to preserve themselves, only to turn green and strong as soon as rains come again.

You can see this wonderful resilience of the plants in Serengeti. During the rainy season, the vast grass plains turn lush green, providing a rich grazing opportunity to hundreds of thousands of the Africa’s most iconic herbivores, only to fade when the dry season comes.

But the problem appears when we try to change these natural cycles and expect a steady crop production or sufficient pasture for livestock from these lands all year long. Under circumstances like these, people often overextract water from available resources like creeks, rivers or even groundwater to irrigate the crops.

Lack of water to support farming and desert sands encroaching villages are already causing trouble to rice farmers throughout the regions of northern China. While farmers despair about their inability to cultivate rice fields, local agronomists confirm that it was the water overextraction to create rice paddies that has significantly contributed to the current desert expansion [10].

The problem of worsening desertification doesn’t have to be linked only to agricultural lands, unsustainable water management happens even in cities and tourist destinations that are build in arid or semi-arid areas. These places often draw high amounts of groundwater from natural aquifers, not letting them naturally replenish and eventually facing water scarcity just like Cape Town in South Africa.

 

“All problems related to desertification can eventually be traced back to water related problems.”

DESIRE Scientific Report no. 4


 

#5 Overpopulation and overexploitation of natural resources

Our planet’s ecosystems sustain life only when balanced. They can cope with incremental challenges and adapt, but beyond a certain tipping point they collapse. Unfortunately, desertification is a proof that in some places, we have reached this tipping point.

A rapid increase in human population, especially in vulnerable areas of Africa and Asia, has exceeded the recovery capacity of dryland ecosystems. As “harsh” as this may sound, the reason is very simple.

More people means higher demand for natural resources (including water(!) and space to grow food and build settlements. But trying to provide for more people easily results in overexploitation of available resources, even if unwillingly. Just look at previously mentioned examples, they all point to this conclusion.

Once the overexploitation takes place, desertification often follows, leaving behind only barren land and misery for those who haven’t left.

One region of the world that has seen many of these negative effects combined is Sub-Saharan Africa. The region currently faces extensive desertification caused by numerous factors. These factors include very high birth rates and thus expansion of agriculture into unsuitable areas, uncontrolled tree cutting for a fuel, all connected with effects of climate change and bad government policies.  

#6 Urbanization and development of tourism

Not many people realize this when walking on the streets of their city or some magnificent tourist resort, but in order to build these structures, original ecosystems had to be irreversibly wiped out. And together with ecosystems disappear even natural resources that were once present.

This means that natural resources, which are continuously needed for the proper functioning of any densely inhabited area, have to be taken from the surrounding environment. However, as the trend of urbanization increases, the demand for resources only grows bigger, drawing more and more resources and leaving behind degraded lands that easily succumb to desertification.

Desertification in urban areas

Furthermore, additional problem arises from the space problems. As cities expand, more land in the vicinity is used for the development projects. Even though this often represents fertile land that would have been suitable for agriculture more. We should not forget that most of the human settlements were built along fertile soils, rivers, or other resourceful places that offered some great advantage to their inhabitants. Their loss to buildings and other infrastructure is, therefore, rather wasteful.    

Land degradation due to urbanization has affected strongly many countries such as Egypt, Iraq, Turkey, Spain and other places with hot climate, where urban and tourist areas spread along the rivers or coastlines, sealing these lands and pushing farming away onto marginal lands, which will only accelerate their desertification over the time [11].

#7 Famine, poverty and political instability

While desertification certainly leads to these problems, they can also be its cause. This is because people on the brink of famine, extreme poverty or political instability in their country need to solve the crisis at the moment and do not think about sustainable cultivation strategies.

Unfortunately, outcomes of their compromised livelihoods are often poor land use practices, such as grazing animals on eroding lands, illegal cutting of forests and unsustainable crop cultivation, which only contribute to the soil destruction beyond repair and put lives of people even more in danger.

Greentumble’s writer Deogracias has described how is the problem of deforestation linked to the livelihood of some people in his country, Malawi. You can read the whole story here to get a better understanding about the situation in this developing country and reasons why preventing desertification gets difficult in some areas.  

#8 Climate change

So much could be written about the effects of climate change on the health of our lands, as climate change can lead to land degradation for many reasons, and it is very often climate change that exacerbates the progress of desertification in increasingly many places.

But it is important to realize one thing if we want to know how does climate change cause desertification. As we continue to remove natural vegetation from landscapes, we change radically the water absorption capacity of soils. With less permanent vegetation that would help retain moisture in soils and with less moisture evaporating into the air from plants, less clouds form in that particular area. That means also less rain throughout the year.

With significantly reduced rainfall, drought occurs and triggers problems such as failing harvests, drying creeks and boreholes, poor pasture that weakens livestock, and more frequent outbreaks of wildfires that destroy remaining vegetation.

It is these problems that pressure people to slip into the vicious cycle of repeating all the previously listed causes of desertification–actions which naturally open up the door to the ecological catastrophe of irreversible land degradation.

One of the very recent examples of climate-induced desertification is the disappearance of the lake Poopó, lying in a high altitude of semi-arid plains in Bolivian Andes. Formerly, the second largest lake in Bolivia filled with diversity of fish and birds had completely dried up just in the span of three years, 2014 to 2017. All that is left of the lake is just a large salt desert. The reasons why this has happened are longer periods of droughts and the overextraction of water for irrigation and mining projects [12].

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What are the effects of desertification?

In the introduction of a document called ‘Desertification: The invisible frontline’ from UNCCD is stated: “Desertification is a silent, invisible crisis that is destabilizing communities on a global scale.”

The document further goes on examining the serious and complex web of problems that have arisen from worsening land degradation of the earth’s drylands, which are home to 2,000 million people, comprise of 44 percent of all the world’s cultivated land and should sustain 50 percent of the world’s livestock [13].

Nomadic herders in Tibet

These are huge numbers and huge level of dependency upon these lands that should not fail us. Do you know what that means? It means that the effects of desertification can be extremely serious and not only for us, but for the balance of the whole planet.

Here is what we can expect…

#1 Vegetation is damaged or destroyed

Desertification reduces the ability of land to support plant life. Loose soil buries plants or exposes their roots to the sun, so they cannot fulfill their function. With plants dying, already scarce rainwater gets washed away instead of being drawn into the soil, which only scales up the problem as remaining plants do not have enough moisture to survive dry spells as they used to.

Additionally, if the land is used for grazing at this stage, it only results in a quicker loss of plant species and total degradation.

#2 Soil becomes infertile

Topsoil is crucial for plant growth because it contains most of the organic matter and 50 percent of important nutrients such as phosphorus and potassium. It is in topsoil where large pores and soil aggregates form, allowing for proper water infiltration and aeration.

As desertification occurs, this most productive layer of the soil gets blown or washed away from the surface rather quickly because there is no vegetation that would protect it, and nutrients with organic material are lost for good. As the soil dries out, it hardens, and it becomes difficult for any rainfall that does occur to penetrate below the soil’s surface.

Due to unfavorable conditions, plants grown on these damaged soils strive and often do not produce sufficient yields. What remains left is only a lifeless pile of dust instead of a life-giving medium.

Furthermore, through the use of unsustainable irrigation techniques, salt concentration can also rise in many cultivated soils, rendering the soil useless for growing crops or other plants.

Iran is a country that has been suffering of this problem. Most of the agricultural land in the country has increased salinity due to large-scale irrigation plans and progressively drier climate.

Faulty irrigation projects have resulted not only in the soil infertility, they have also decreased water table of the country’s largest lakes by 80 percent and more, exposing shores to the effects of rapid drying out and land degradation [14].

#3 Soil erosion gets worse

As you may have noticed, desertification problems are often related and lead to one another. The link between soil erosion and other consequences of desertification only confirms this, as erosion is another negative outcome but also a catalyst of previously mentioned problems.

In many cases, increased water runoff from desertified areas wreaks havoc on neighboring lands, eroding soils, damaging vegetation and making soils extremely vulnerable to encroaching desert.

When this happens, weakening soils get also directly exposed to wind, which often picks up last pieces of drying topsoil and mixes them with dust from already degraded parts, exacerbating the problem and creating far-reaching dust storms.

Desertification and soil erosion

This is exactly what has been happening in the Sahel.

According to the newest data, the Sahara Desert has been gradually spreading over the grasslands in the neighboring Sahel area. Compared with the data from 1920s, Sahara has already expanded by 10 percent.

In recent years, the desert has advanced southward to lake Chad, which used to be an important source of water and livelihood for 30 million people from eight African countries, but dramatic declines in water level due to droughts and loss of land to desertification have brought only insecurity and suffering upon these communities [16].

Besides other contributing factors, Sahel farmers are partially to blame because they have removed trees to cultivate crops in this semi-arid area, and thus speeding up Sahel desertification by exposing soils to erosion [15].

Soil erosion is often one of the final steps that closes the loop of continual soil deterioration that is difficult to revert.

#4 Increased vulnerability to natural disasters

Desertification makes natural disasters worse because it reduces natural resilience of ecosystems. This means that affected areas and even adjacent areas have compromised capacity of withstanding extreme weather events. Desertification also increases vulnerability of whole regions to the unpredictable effects of climate change.

Events such as flash floods, landslides and dust storms, become stronger in areas with heavily degraded soils. Without plants stabilizing the soil and slowing down the runoff, rainwater flows faster and floods human settlements in the blink of an eye.

Except causing damage, flood water also picks up many unwanted pollutants while making its progress through urban areas, landfills, wastelands, or agricultural lands where fertilizers and pesticides were used. These pollutants then remain deposited in the soil or wash off into rivers, creeks or lakes.

Flooding is not the only problem, sand storms are another big issue, mainly because wind-blown particles (including those that are polluted) can travel long distances and cause health problems to people even in distant urban areas.

Inhabitants of the Aral Sea region are well-familiar with this problem. Watch the video to learn more about destructive sandstorms and advancing desertification they have to face more frequently.

Video credit: Youtube / DW News

#5 Polluted sources of drinking water

Vegetation plays an important role in cleaning our water. Plants and trees function like natural water filters, storing pollutants, such as heavy metals, pesticide residues, fertilizers and other, in their own bodies. As mentioned previously, grasses and other perennial plants also prevent water runoff by slowing it down and promoting rainwater infiltration into soils.

Barren soils lack this green filter, and therefore, many harmful substances enter groundwater reservoirs or easily wash off into lakes and rivers.

Besides constantly eroding soils by creating gullies and channels each time it rains, water also picks up loosen soil particles and transports them into water bodies. This leads to increased sedimentation and eutrophication–both processes disturb aquatic ecosystems and deteriorate water quality.

What’s worse is that these effects can be felt even thousands of miles away from where the problem originated.  There have been many records of water scarcity and pollution problems that are linked to desertification or other forms of land degradation across dry African and Asian countries.

For example, China’s autonomous region of Ningxia owes its existence to the Yellow River, which has been the only life giver to communities of rice farmers in this arid land that is encircled by sand dunes. Unfortunately, due to the unsustainable water management of diverting water to rice paddies, soil salinity has increased, forcing farmers to use high amounts of fertilizer to save their harvest. And it is these fertilizers that are poisoning scarce sources of potable water, as they are flushed with every rain into the river and drinking wells of people [10].

#6 Rise of famine, poverty and social conflicts

Desertification is a serious form of land degradation that results in the destruction of natural ecosystems and the end of services they provide for us. This includes natural filtration of water for drinking, climate regulation, recycling of nutrients, carbon sequestration, soil regeneration. There is probably no need to explain how crucial these services are for our wellbeing.

When ecosystems cease to support us and our livestock, only bad things happen. Bad things like prolonged episodes of famine, diseases from water scarcity, fights for thinning resources and death of people, children, animals.

Many African countries, especially in the Sahel area, are experiencing insecurity that only gets worse and worse every year. Climate change, bad management of scarce resources, weak political structure only lead to hunger, which in turn gives rise to conflicts.

One of the latest humanitarian crises has been declared in countries that have been dependent upon resources provided by lake Chad, where lake water gets quickly replaced by inhospitable sand dunes, destroying fishing and farming communities.

Not only that up to 6 million people suffer of hunger in the Chad Basin recently, they are also terrorized by Boko Haram, one of the most dangerous terrorist groups in the world. Boko Haram is believed to constitute of young people deprived of livelihood possibilities due to constant disputes over disappearing water among diverse ethnic groups, inhabiting the area [17].

Desertification has destroyed even lives of nomadic Bedouins and farmers in Syria. Due to unrestricted grazing of the steppe by livestock combined with the influence of climate change, Syrian land has become so damaged that it has turn into lifeless dust. According to expert opinions from FAO and UN, this high level of land loss to desertification is what has triggered a civil war in the country. The war that has been going for nearly a decade now [18,19,20]

#7 Forcing mass migrations

People have been always on the lookout for fertile lands where they can build their settlements and prosper over long time periods. It is no wonder, that throughout history, desertification events have been a major driver behind migrations of large human populations.

One of the biggest transitions that has forced first farmers in the early Holocene to abandon their lands happened when their previously fertile lands started to turn drier and drier. Unable to grow crops, farmers had to leave their villages in search of better lands. And it was good they did, because since then, the area they have been cultivating became one of the biggest deserts on Earth – the Sahara Desert.

While the main reason for desertification of the Sahara lies in slight changes of the Earth’s orbit, which affected the intensity of the monsoonal rains in the area, early farmers might have been to blame as well.

According to a new hypothesis, scientists believe that herds of domestic goats and vegetation burning to cultivate grasslands of the previously green Sahara could have sped up the process of drying up. Be it true or not, unfavorable conditions still forced early people to leave their homes and everything they were familiar with.

The same happens even at this very moment and will be happening in the future. UNCCD estimates that advancing desertification could displace globally 50 million people in the next 10 years [21]. And when you think about it, it’s just a natural reaction of any living organism to survive – “fight or flight.”

Migration is the effect of desertification

Since small subsistence farmers do not have the means to ward off sand dunes crashing their houses and burying their crops, all they have left is to gather their possessions and leave.

In many instances, these people go to larger cities, hoping for better life by finding a new livelihood. Unfortunately, that’s not always the case, as they often lack the skills that are needed for urban jobs. Some of these families then end up living in poverty in slums.

#8 Caused historical collapses of civilizations

There are many historical accounts of how various people groups throughout human history experienced collapse of their civilization as drought and desertification occurred to their lands. The reason is simple, people lost their ability to grow food, water resources became scarce and their animals got weak from not having enough to eat.

These negative events are directly linked to the wellbeing of people. As soon as livelihoods are endangered, people turn against each other, which sets in motion series of events that lead to the collapse.

Examples of civilizations that met their doom due to droughts include the Carthage Civilization, the Harappan Civilization, people groups in Ancient Greece, the Roman Empire, and people groups in Ancient China [22].

#9 Extinction of species

Extended droughts, prolonged flooding or sudden extreme changes in temperature can deplete food sources of species causing starvation. Species that once lived in a fertile and productive climate may not survive in a newly desertified region.

With a changing ecosystem, species must adapt to their new climate or migrate to a more favorable climate. If they fail to do so, they will become extinct for their inability to cope with a sudden change of their environment.

This is another very alarming aspect of the desertification problem, because we need biodiverse ecosystems to survive. We need abundance of plants and animal species richness to have oxygen to breathe, clean water to drink and nutritious food to eat. If biodiverse ecosystems disappear, we will be left with pollution, drought, hunger and lack of resources.

That doesn’t sounds like such a bright future, does it?

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This list of causes and impacts of desertification is just a brief fraction of the whole scope of such an extensive problem taking place on our lands every day.

Majority of those who are affected the most by this problem are as usual the world’s poorest nations where people struggle daily with the direct impacts of climate turning against them, and deserts claiming more of their already scarce soils.

Therefore, it is important to realize after reading this article how valuable soil conservation is. And try to do everything in our power to help protect natural resources we have.

 
 

References

[1] https://www.un.org/press/en/2012/gaef3352.doc.htm
[2] https://goo.gl/vdXywp
[3] http://www.statemaster.com/graph/geo_lan_acr_tot-geography-land-acreage-total
[4] https://www.theguardian.com/environment/2010/dec/16/desertification-climate-change
[5] https://www.theguardian.com/global-development/2017/oct/13/tunisia-battle-to-keep-desert-at-bay-acacias-for-all
[6] https://ir.library.oregonstate.edu/concern/articles/zs25x899d?locale=en
[7] https://www.environment.nsw.gov.au/topics/land-and-soil/soil-degradation/salinity/type-of-salinity-and-their-prevention
[8] https://en.wikipedia.org/wiki/Aral_Sea
[9] http://www.environmentportal.in/files/desertification.pdf
[10] https://www.pri.org/stories/2008-12-11/china-faces-desertification
[11] http://www.fao.org/3/x5322e/x5322e04.htm
[12] https://www.theguardian.com/world/2018/jan/04/the-ecological-catastrophe-that-turned-a-vast-bolivian-lake-to-a-salt-desert
[13] https://www.unccd.int/frequently-asked-questions-faq
[14] https://www.sciencedirect.com/science/article/pii/B9780123948472000152
[15] https://www.smithsonianmag.com/science-nature/great-green-wall-stop-desertification-not-so-much-180960171/
[16] https://ejatlas.org/conflict/lake-chad-desertification-chad
[17] https://www.downtoearth.org.in/coverage/water/lake-chad-forgotten-crisis-56974
[18] https://ohiostate.pressbooks.pub/sciencebites/chapter/the-effects-of-climate-change-on-the-syrian-uprising/
[19] https://theecologist.org/2015/jun/05/over-grazing-and-desertification-syrian-steppe-are-root-causes-war
[20] http://www.thenewhumanitarian.org/news/2010/06/15/act-now-stop-desertification-says-fao
[21] https://www.unisdr.org/files/1794_VL102205.pdf
[22] https://news.nationalgeographic.com/news/2013/10/131024-drought-bronze-age-pollen-archaeology/