Desertification is a type of land degradation in drylands in which biological productivity is lost due to natural processes or induced by human activities whereby fertile areas become arid.[1][2] It is the spread of arid areas caused by a variety of factors, such as overexploitation of soil as a result of human activity and the effects of climate change.[3][4] Geographic areas most affected include the Sahel region in Africa, the Gobi Desert and Mongolia in Asia as well as parts of South America. Drylands occupy approximately 40–41% of Earth's land area and are home to more than 2 billion people.[5]

World map from 1998 showing global desertification vulnerability

Effects of desertification include sand and dust storms, food insecurity, vegetation patterning and increasing poverty. There are many possible countermeasures such as reforestation, soil restoration, desert reclamation and managed grazing.

Throughout geological history, the development of deserts has occurred naturally. In recent times, the influences of human activity, improper land management, deforestation and climate change on desertification is the subject of many scientific investigations.[6][7][8]

Definitions edit

As recently as 2005, considerable controversy existed over the proper definition of the term "desertification." Helmut Geist (2005) identified more than 100 formal definitions.[9] The most widely accepted of these was that of the Princeton University Dictionary which defined it as "the process of fertile land transforming into desert typically as a result of deforestation, drought or improper/inappropriate agriculture".[citation needed] This definition clearly demonstrated the interconnectedness of desertification and human activities, in particular land use and land management practices. It also highlighted the economic, social and environmental implications of desertification.
However, this original understanding that desertification involved the physical expansion of deserts has been rejected as the concept has further evolved since then.[10] Desertification has been defined in the text of the 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 according to Hulme and Kelly, (1993)."[11]

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".[12]

Geographic areas affected edit

Drylands occupy approximately 40–41% of Earth's land area and are home to more than 2 billion people.[13][5] 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 kilometers, that about 1–6% of the inhabitants of drylands live in desertified areas, and that a billion people are under threat from further desertification.[14][15]

Sahel edit

The impact of climate change and human activities on desertification are exemplified in the Sahel region of Africa. The region is characterized by a dry hot climate, high temperatures and low rainfall (100–600 mm per year).[16] So, droughts are the rule in the Sahel region.[17] The Sahel has lost approximately 650,000 km2 of its productive agricultural land over the past 50 years;[18] the propagation of desertification in this area is considerable.[19][20]

 
Sahel region of Mali

The climate of the Sahara has undergone enormous variations over the last few hundred thousand years,[21] oscillating between wet (grassland) and dry (desert) every 20,000 years[22] (a phenomenon believed to be caused by long-term changes in the North African climate cycle that alters the path of the North African Monsoon, caused by an approximately 40000-year cycle in which the axial tilt of the earth changes between 22° and 24.5°).[23] 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.[24]

Lake Chad, located in the Sahel region, has undergone desiccation due to water withdrawal for irrigation and decrease in rainfall.[25] The lake has shrunk by over 90% since 1987, displacing millions of inhabitants.[26] Recent efforts have managed to make some progress toward its restoration, but it is still considered to be at risk of disappearing entirely.[27]

To limit desertification the Great Green Wall (Africa) initiative was started in 2007 involving the planting of vegetation along a stretch of 7,775 kms, 15 kms wide, involving 22 countries to 2030.[28] The purpose of this mammoth planting initiative is to enhance retention of water in the ground following the seasonal rainfall, thus promoting land rehabilitation and future agriculture. Senegal has already contributed to the project by planting 50,000 acres of trees. It is said to have improved land quality and caused an increase in economic opportunity in the region.[29]

Gobi Desert and Mongolia edit

Another major area that is being impacted by desertification is the Gobi Desert located in Northern China and Southern Mongolia. The Gobi Desert is the fastest expanding desert on Earth, as it transforms over 3,600 square kilometres (1,400 square miles) of grassland into wasteland annually.[30] Although the Gobi Desert itself is still a distance away from Beijing, reports from field studies state there are large sand dunes forming only 70 km (43.5 mi) outside the city.[31][32]

In 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.[33][34] During the period 1940 to 2015, the mean air temperature increased by 2.24 °C.[35] The warmest ten-year period was during the latest decade to 2021. Precipitation has decreased by 7% over this period resulting in increased arid conditions throughout Mongolia. The Gobi desert continues to expand northward, with over 70% of Mongolia’s land degraded through overgrazing, deforestation, and climate change.[36] In addition, the Mongolia government has listed forest fires, blights, unsustainable forestry and mining activities as leading causes of desertification in the country.[37] The transition from sheep to goat farming in order to meet export demands for cashmere wool has caused degradation of grazing lands. Compared to sheep, goats do more damage to grazing lands by eating roots and flowers.[38]

The Gobi Desert is expanding through desertification, most rapidly on the southern edge into China, which is seeing 3,600 km2 (1,390 sq mi) of grassland overtaken every year. Dust storms increased in frequency between 1996 and 2016, causing further damage to China's agriculture economy. However, in some areas desertification has been slowed or reversed.[39]

The northern and eastern boundaries between desert and grassland are constantly changing. This is mostly due to the climate conditions before the growing season, which influence the rate of evapotranspiration and subsequent plant growth.[40]

The expansion of the Gobi is attributed mostly to human activities, locally driven by deforestation, overgrazing, and depletion of water resources, as well as to climate change.[39]

China has tried various plans to slow the expansion of the desert, which have met with some success.[41] The Three-North Shelter Forest Program (or "Green Great Wall") is a Chinese government tree-planting project begun in 1978 and set to continue through 2050. The goal of the program is to reverse desertification by planting aspen and other fast-growing trees on some 36.5 million hectares across some 551 counties in 12 provinces of northern China.[42][43]

South America edit

South America is another area vulnerable by desertification, as 25% of the land is classified as drylands[44] and over 68% of the land area has undergone soil erosion as a result of deforestation and overgrazing.[45] 27 to 43% of the land areas in Bolivia, Chile, Ecuador and Peru are at risk due to desertification. In Argentina, Mexico and Paraguay greater than half the land area is degraded by desertification and cannot be used for agriculture. In Central America drought has caused increased unemployment and decreased food security - also causing migration of people. Similar impacts have been seen in rural parts of Mexico where about 1000 square kms of land have been lost yearly due to desertification.[45] In Argentina desertification has the potential to disrupt the nation's food supply.[46]

Causes edit

Preventing man-made overgrazing
Goats inside of a pen in Norte Chico, Chile. Overgrazing of drylands by poorly managed traditional herding is one of the primary causes of desertification.
Wildebeest in Masai Mara during the Great Migration. Overgrazing is not necessarily caused by nomadic grazers in large travelling herd populations.[47][48]

Immediate causes edit

The immediate cause of desertification 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 for fuel or construction materials. Though 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.[49] 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.

Influence of human activities edit

Early studies argued one of the most common causes of desertification was overgrazing, over consumption of vegetation by cattle or other livestock.[50] However, the role of local overexploitation in driving desertification in the recent past is controversial.[51] Drought in the Sahel region is now thought to be principally the result of seasonal variability in rainfall caused by large-scale sea surface temperature variations, largely driven by natural variability and anthropogenic emissions of aerosols (reflective sulphate particles) and greenhouse gases.[52] As a result, changing ocean temperature and reductions in sulfate emissions have caused a re-greening of the region.[52] This has led some scholars to argue that agriculture-induced vegetation loss is a minor factor in desertification.[51]

 
A shepherd guiding his sheep through the high desert outside Marrakech, Morocco

Human population dynamics have a considerable impact on overgrazing, over-farming and deforestation, as previously acceptable techniques have become unsustainable.[53]

There are multiple reasons farmers use intensive farming as opposed to extensive farming but the main reason is to maximize yields.[54] 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.[55][56]

Natural variations edit

Scientists agree that the existence of a desert in the place where the Sahara desert is now located is due to natural variations in solar insolation due to orbital precession of the Earth.[57] Such variations influence the strength of the West African Monsoon, inducing feedback in vegetation and dust emission that amplify the cycle of wet and dry Sahara climate.[58] There is also a suggestion the transition of the Sahara from savanna to desert during the mid-Holocene was partially due to overgrazing by the cattle of the local population.[59]

Effects edit

Sand and dust storms edit

 
View of Sydney Harbour Bridge covered in dust

There has been a 25% increase in global annual dust emissions between the late nineteenth century to present day.[60] 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 [cause] lower soil moisture and vegetative cover”.[61]

Dust storms can contribute to certain respiratory disorders such as pneumonia, skin irritations, asthma and many more.[62] 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.[63][64] Dust particles in the air scatter incoming radiation from the sun (Hassan, 2012). 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.[54]

Food insecurity edit

Global food security is being threatened by desertification. The more that 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.[65] The violent herder–farmer conflicts in Nigeria, Sudan, Mali and other countries in the Sahel region have been exacerbated by climate change, land degradation and population growth.[66][67][68]

Vegetation patterning edit

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.[69] One outcome of this observation suggests an optimal planting strategy for agriculture in arid environments.[70]

Increasing poverty edit

 
Wind erosion outside Leuchars

At least 90% of the inhabitants of drylands live in developing countries, where they also suffer from poor economic and social conditions.[71] 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.[72]

Many underdeveloped countries are affected by overgrazing, land exhaustion and overdrafting of groundwater due to 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 marginalization of these zones. When unfavorable agri-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.[73]

Desertification often causes rural lands to become unable to support the same sized populations that previously lived there. This results in mass migrations out of rural areas and into urban areas particularly in Africa creating unemployment and slums.[74][75] 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.[76][77]

In 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 on 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.[78]

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.[79]

There is, however, increased global advocacy e.g. the UN SDG 15[80] to combat desertification and restore affected lands.

Countermeasures edit

 
Anti-sand shields in north Sahara, Tunisia
 
Jojoba plantations, such as those shown, have played a role in combating edge effects of desertification in the Thar Desert, India.[81]
 
Saxaul planted along roads in Xinjiang near Cherchen to slow desertification

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.[82] Another issue is a lack of political will, and lack of funding to support land reclamation and anti-desertification programs.[83]

Desertification is recognized as a major threat to biodiversity. Some countries have developed biodiversity action plans to counter its effects, particularly in relation to the protection of endangered flora and fauna.[84][85]

Reforestation edit

Reforestation 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. 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.[86] The Food and Agriculture Organization of the United Nations launched the FAO Drylands Restoration Initiative in 2012 to draw together knowledge and experience on dryland restoration.[87] 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.[88]

The "Green Wall of China" is a high-profile example of one method that has been finding success in this battle with desertification.[89] 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.[90] The green wall of China has decreased desert land in China by an annual average of 1,980 square km.[91] The frequency of sandstorms nationwide have fallen 20% due to the green wall.[92] 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.[93]

 
The Great Green Wall, participating countries and Sahel. In September 2020, it was reported that the GGW had covered only 4% of the planned area.[94]

In 2007 the African Union started the Great Green Wall of Africa project in order to combat desertification in 20 countries.[95] 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 36 million hectares of land, and by 2030 the initiative plans to restore a total of 100 million hectares.[96] The Great Green Wall has created many job opportunities for the participating countries, with over 20,000 jobs created in Nigeria alone.[97]

Soil restoration edit

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, woodlots and windbreaks. Windbreaks are made from trees and bushes and are used to reduce soil erosion and evapotranspiration.[98] They were widely encouraged by development agencies from the middle of the 1980s in the Sahel area of Africa.

Some soils (for example, clay), due to lack of water can become consolidated rather than porous (as in the case of sandy soils). Some techniques as zaï or tillage are then used to still allow the planting of crops.[99]

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. This method was invented by Peter Westerveld.[100]

Enriching of the soil and restoration of its fertility is often achieved by plants. Of these, leguminous plants which extract nitrogen from the air and fix it in the soil, succulents (such as Opuntia),[101] and food crops/trees as grains, barley, beans and dates are the most important. Sand fences 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 farmers are reluctant to use it, especially in areas where subsistence farming is common.[102] Several nations, including India, Zambia, and Malawi have responded to this by implementing subsidies to help encourage adoption of this technique.[103]

Some research centres (such as Bel-Air Research Center IRD/ISRA/UCAD) are also experimenting with the inoculation of tree species with 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).[104]

The bioengineering 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.[105]

Desert reclamation edit

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 desert in 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.[106]

Farmer-managed natural regeneration (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.[107]

Managed grazing edit

Restored grasslands store CO2 from the atmosphere as organic plant material. Grazing livestock, usually not left to wander, consume the grass and minimize its growth.[108] A method proposed to restore grasslands uses fences with many small paddocks, 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.[108][109][110] 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.[108]

History edit

The world's most noted deserts have been formed by natural processes interacting over long intervals of time. During most of these times, deserts have grown and shrunk independently of human activities. Paleodeserts are large sand seas now inactive because they are stabilized by vegetation, some extending beyond the present margins of core deserts, such as the Sahara, the largest hot desert.[111]

Historical evidence shows that the serious and extensive land deterioration occurring several centuries ago in arid regions had three centers: the Mediterranean, the Mesopotamian Valley, and the Loess Plateau of China, where population was dense.[112]

The earliest known discussion of the topic arose soon after the French colonization of West Africa, when the Comité d'Etudes commissioned a study on desséchement progressif to explore the prehistoric expansion of the Sahara Desert.[113] The modern study of desertification emerged from the study of the 1980s drought in the Sahel.[51]

See also edit


Other related portals:

References edit

  1. ^ "Desertification | Description, Causes, & Impacts | Britannica". www.britannica.com. 2023-08-23. Retrieved 2023-09-22.
  2. ^ "Desertification - an overview | ScienceDirect Topics". www.sciencedirect.com. Archived from the original on 2022-04-03. Retrieved 2022-04-03.
  3. ^ "Sustainable development of drylands and combating desertification". Archived from the original on 4 August 2017. Retrieved 21 June 2016.
  4. ^ Zeng, Ning; Yoon, Jinho (1 September 2009). "Expansion of the world's deserts due to vegetation-albedo feedback under global warming". Geophysical Research Letters. 36 (17): L17401. Bibcode:2009GeoRL..3617401Z. doi:10.1029/2009GL039699. ISSN 1944-8007. S2CID 1708267.
  5. ^ a b https://unemg.org/2018/images/emgdocs/publications/Global_Drylands_Full_Report.pdf
  6. ^ Liu, Ye; Xue, Yongkang (5 March 2020). "Expansion of the Sahara Desert and shrinking of frozen land of the Arctic". Scientific Reports. 10 (1): 4109. Bibcode:2020NatSR..10.4109L. doi:10.1038/s41598-020-61085-0. PMC 7057959. PMID 32139761.
  7. ^ An, Hui; Tang, Zhuangsheng; Keesstra, Saskia; Shangguan, Zhouping (1 July 2019). "Impact of desertification on soil and plant nutrient stoichiometry in a desert grassland". Scientific Reports. 9 (1): 9422. Bibcode:2019NatSR...9.9422A. doi:10.1038/s41598-019-45927-0. PMC 6603008. PMID 31263198.
  8. ^ Han, Xueying; Jia, Guangpu; Yang, Guang; Wang, Ning; Liu, Feng; Chen, Haoyu; Guo, Xinyu; Yang, Wenbin; Liu, Jing (10 December 2020). "Spatiotemporal dynamic evolution and driving factors of desertification in the Mu Us Sandy Land in 30 years". Scientific Reports. 10 (1): 21734. Bibcode:2020NatSR..1021734H. doi:10.1038/s41598-020-78665-9. PMC 7729393. PMID 33303886.
  9. ^ Geist, Helmut (2017-10-01). The Causes and Progression of Desertification. London: Routledge. doi:10.4324/9781315240855. ISBN 978-1-315-24085-5.
  10. ^ Rafferty, John P.; Pimm, Stuart L. (January 26, 2023). "Desertification". Encyclopædia Britannica. Retrieved 2019-11-06. The concept does not refer to the physical expansion of existing deserts but rather to the various processes that threaten all dryland ecosystems.
  11. ^ Hulme, Mike; Kelly, Mick (1993). "Exploring the links between Desertification and Climate Change". Environment: Science and Policy for Sustainable Development. 35 (6): 4–45. Bibcode:1993ESPSD..35f...4H. doi:10.1080/00139157.1993.9929106. ISSN 0013-9157.
  12. ^ Geist, Helmut J.; Lambin, Eric F. (2004). "Dynamic Causal Patterns of Desertification". BioScience. 54 (9): 817. doi:10.1641/0006-3568(2004)054[0817:DCPOD]2.0.CO;2. ISSN 0006-3568.
  13. ^ Johnson, Pierre-Marc; Johnson, Pierre Marc, eds. (2006). Governing global desertification: linking environmental degradation, poverty and participation. Global environmental governance series. Aldershot: Ashgate [u.a.] ISBN 978-0-7546-4359-3.
  14. ^ "UNCCD: Impact and role of drylands". UNCCD. 10 October 2017. Archived from the original on 7 November 2019. Retrieved 7 November 2019.
  15. ^ World Bank (2009). Gender in agriculture sourcebook. World Bank Publications. p. 454. ISBN 978-0-8213-7587-7. Archived from the original on 2023-07-30. Retrieved 2016-05-16.
  16. ^ Nicholson, Sharon E. (2013-02-17). "The West African Sahel: A Review of Recent Studies on the Rainfall Regime and Its Interannual Variability". International Scholarly Research Notices. 2013: e453521. doi:10.1155/2013/453521.
  17. ^ Riebeek, Holli (2007-01-03). "Defining Desertification : Feature Articles". earthobservatory.nasa.gov. Archived from the original on 2016-12-01. Retrieved 2016-11-30.
  18. ^ https://www.thegeographeronline.net/uploads/2/6/6/2/26629356/a116_sahel.pdf
  19. ^ Nicholson, S. E.; Tucker, C. J.; Ba, M. B. (1 May 1998). "Desertification, Drought, and Surface Vegetation: An Example from the West African Sahel". Bulletin of the American Meteorological Society. 79 (5): 815–830. Bibcode:1998BAMS...79..815N. doi:10.1175/1520-0477(1998)079<0815:DDASVA>2.0.CO;2.
  20. ^ "Land Resource Stresses and Desertification in Africa". United States Department of Agriculture. Archived from the original on 1 April 2022. Retrieved 24 November 2020.
  21. ^ Kevin White; David J. Mattingly (2006). "Ancient Lakes of the Sahara". American Scientist. 94 (1): 58–65. doi:10.1511/2006.57.983.
  22. ^ Jennifer Chu (January 2, 2019). "A "pacemaker" for North African climate". MIT News. Archived from the original on January 15, 2022. Retrieved January 20, 2020.
  23. ^ Houérou, Henry N. (2008-12-10). Bioclimatology and Biogeography of Africa. Springer Science & Business Media. ISBN 978-3-540-85192-9. Archived from the original on 2023-07-30. Retrieved 2020-12-11.
  24. ^ Christian Bouquet (December 2017). "Le Sahara entre ses deux rives. Éléments de délimitation par la géohistoire d'un espace de contraintes". Géoconfluences. Archived from the original on 2022-02-10. Retrieved 2018-01-25. Mais il aurait progressé de 250 km vers le sud depuis 1900 (Mainguet, 2003), et dépasserait donc 9 millions de km² soit 30 % de la superficie totale du continent africain.
  25. ^ Okpara, Uche T.; Stringer, Lindsay C.; Dougill, Andrew J. (November 2016). "Lake drying and livelihood dynamics in Lake Chad: Unravelling the mechanisms, contexts and responses". Ambio. 45 (7): 781–795. Bibcode:2016Ambio..45..781O. doi:10.1007/s13280-016-0805-6. PMC 5055484. PMID 27371137.
  26. ^ Jiang, Ingrid (2022-08-12). "A Remarkable Size Shrinking in Lake Chad". ArcGIS StoryMaps. Retrieved 2023-09-22.
  27. ^ Onamuti, Olapeju Y.; Okogbue, Emmanuel C.; Orimoloye, Israel R. (8 November 2017). "Remote sensing appraisal of Lake Chad shrinkage connotes severe impacts on green economics and socio-economics of the catchment area". Royal Society Open Science. 4 (11): 171120. doi:10.1098/rsos.171120. PMC 5717671. PMID 29291097.
  28. ^ "Great Green Wall Initiative". UNCCD. Retrieved 2023-09-22.
  29. ^ "The Great Green Wall | National Geographic Society". Archived from the original on 2022-12-22. Retrieved 2022-12-22.
  30. ^ Rechtschaffen, Daniel. "How China's Growing Deserts Are Choking The Country". Forbes. Archived from the original on 2022-02-16. Retrieved 2022-08-28.
  31. ^ Welker, Lauren (2009). The Desertification of the Gobi Desert and Its Effect on Beijing (PDF) (Unpublished manuscript). University of Texas-Austin School of Geosciences. Archived (PDF) from the original on 2014-01-24.
  32. ^ "Gobi Desert: A Complete Guide to East Asia's Largest Desert". Young Pioneer Tours. 2020-03-25. Archived from the original on 2023-07-30. Retrieved 2022-04-03.
  33. ^ "What Is Desertification and How Does It Impact Mongolia?". Breathe Mongolia – English. Archived from the original on 2022-04-01. Retrieved 2022-04-03.
  34. ^ Han, Jie; Dai, Han; Gu, Zhaolin (2021-12-01). "Sandstorms and desertification in Mongolia, an example of future climate events: a review". Environmental Chemistry Letters. 19 (6): 4063–4073. Bibcode:2021EnvCL..19.4063H. doi:10.1007/s10311-021-01285-w. ISSN 1610-3661. PMC 8302971. PMID 34335128. Archived from the original on 2023-07-30. Retrieved 2022-04-03.
  35. ^ Han, Jie; Dai, Han; Gu, Zhaolin (2021-12-01). "Sandstorms and desertification in Mongolia, an example of future climate events: a review". Environmental Chemistry Letters. 19 (6): 4063–4073. Bibcode:2021EnvCL..19.4063H. doi:10.1007/s10311-021-01285-w. ISSN 1610-3661. PMC 8302971. PMID 34335128.
  36. ^ https://www.adb.org/sites/default/files/publication/31145/making-grasslands-sustainable-mongolia.pdf
  37. ^ https://wedocs.unep.org/bitstream/handle/20.500.11822/8918/-Report%20on%20the%20state%20of%20the%20environment%20of%20Mongolia%20(2008-2010)-2011Report-State-of-environment-Mongolia.pdf?sequence=3&isAllowed=y#:~:text=The%20Report%20of%20State%20of,damaged%20by%20mining%20activities%20are
  38. ^ Dorj, O.; Enkhbold, M.; Lkhamyanjin, S.; Mijiddorj, Kh.; Nosmoo, A.; Puntsagnamil, M.; Sainjargal, U. (2013), Heshmati, G. Ali; Squires, Victor R. (eds.), "Mongolia: Country Features, the Main Causes of Desertification and Remediation Efforts", Combating Desertification in Asia, Africa and the Middle East, Dordrecht: Springer Netherlands, pp. 217–229, doi:10.1007/978-94-007-6652-5_11, ISBN 978-94-007-6651-8
  39. ^ a b "Living in China's Expanding Deserts (Published 2016)". The New York Times. 2016-10-24. ISSN 0362-4331. Retrieved 2021-01-09.
  40. ^ F. Yu, K. P. Price, J. Ellis, J. J. Feddema, P. Shi (2004). "Interannual variations of the grassland boundaries bordering the eastern edges of the Gobi Desert in central Asia". International Journal of Remote Sensing. 25: 327–346.
  41. ^ "Focus - Can the 'Great Green Wall' stop desertification in China?". France 24. 2018-01-30. Retrieved 2021-01-09.
  42. ^ Claudio O. Delang, China's Soil Pollution and Degradation Problems (Routledge, 2014).
  43. ^ "China's efforts to halt the Gobi provide a blueprint for tackling desertification | UNCCD". www.unccd.int. Retrieved 2021-01-09.
  44. ^ "Soil Degradation Threatens Nutrition in Latin America - World". ReliefWeb. 16 June 2016. Archived from the original on 2022-04-03. Retrieved 2022-04-03.
  45. ^ a b "Why We Should Invest in Land Management in Latin America". www.nrdc.org. 2018-06-15. Retrieved 2023-09-25.
  46. ^ Torres, Laura; Abraham, Elena M.; Rubio, Clara; Barbero-Sierra, Celia; Ruiz-Pérez, Manuel (7 July 2015). "Desertification Research in Argentina". Land Degradation & Development. 26 (5): 433–440. Bibcode:2015LDeDe..26..433T. doi:10.1002/ldr.2392. hdl:11336/48401. S2CID 129476957.
  47. ^ Laduke, Winona (1999). All Our Relations: Native Struggles for Land and Life. Cambridge, MA: South End Press. p. 146. ISBN 978-0896085992. Retrieved 30 March 2015.
  48. ^ Duval, Clay. "Bison Conservation: Saving an Ecologically and Culturally Keystone Species" (PDF). Duke University. Archived from the original (PDF) on March 8, 2012. Retrieved April 13, 2015.
  49. ^ Geeson, Nichola; et al. (2002). Mediterranean desertification: a mosaic of processes and responses. John Wiley & Sons. p. 58. ISBN 978-0-470-84448-9. Archived from the original on 2023-07-30. Retrieved 2016-05-16.
  50. ^ Charney, J. G. (April 1975). "Dynamics of deserts and drought in the Sahel". Quarterly Journal of the Royal Meteorological Society. 101 (428): 193–202. Bibcode:1975QJRMS.101..193C. doi:10.1002/qj.49710142802. Archived from the original on 2023-07-30. Retrieved 2022-05-24.
  51. ^ a b c Behnke, Roy; Mortimore, Michael, eds. (2016). "The End of Desertification?". Springer Earth System Sciences. doi:10.1007/978-3-642-16014-1. ISBN 978-3-642-16013-4. ISSN 2197-9596. S2CID 132424053.
  52. ^ a b Biasutti, Michela (July 2019). "Rainfall trends in the African Sahel: Characteristics, processes, and causes". WIREs Climate Change. 10 (4): e591. Bibcode:2019WIRCC..10E.591B. doi:10.1002/wcc.591. ISSN 1757-7780. PMC 6617823. PMID 31341517.
  53. ^ Epule, Terence Epule; Peng, Changhui; Lepage, Laurent (February 2015). "Environmental refugees in sub-Saharan Africa: a review of perspectives on the trends, causes, challenges and way forward". GeoJournal. 80 (1): 79–92. doi:10.1007/s10708-014-9528-z. ISSN 0343-2521. S2CID 154503204.
  54. ^ a b "Explainer: Desertification and the role of climate change". Carbon Brief. 2019-08-06. Archived from the original on 2022-02-10. Retrieved 2019-10-22.
  55. ^ Nations, United. "World Day to Combat Desertification and Drought". United Nations. Retrieved 2023-09-11.
  56. ^ "Intensive agriculture". Encyclopedia Britannica. Archived from the original on 2008-06-24. Retrieved 2019-11-19.
  57. ^ Tierney, Jessica E.; Pausata, Francesco S. R.; deMenocal, Peter B. (2017-01-06). "Rainfall regimes of the Green Sahara". Science Advances. 3 (1): e1601503. Bibcode:2017SciA....3E1503T. doi:10.1126/sciadv.1601503. ISSN 2375-2548. PMC 5242556. PMID 28116352.
  58. ^ Pausata, Francesco S. R.; Messori, Gabriele; Zhang, Qiong (2016-01-15). "Impacts of dust reduction on the northward expansion of the African monsoon during the Green Sahara period". Earth and Planetary Science Letters. 434: 298–307. Bibcode:2016E&PSL.434..298P. doi:10.1016/j.epsl.2015.11.049. ISSN 0012-821X.
  59. ^ K. Wright, David; Rull, Valenti; Roberts, Richard; Marchant, Rob; Gil-Romera, Graciela (26 January 2017). "Humans as Agents in the Termination of the African Humid Period". Frontiers in Earth Science. 5: 4. Bibcode:2017FrEaS...5....4W. doi:10.3389/feart.2017.00004.
  60. ^ Stanelle, Tanja; Bey, Isabelle; Raddatz, Thomas; Reick, Christian; Tegen, Ina (2014-12-16). "Anthropogenically induced changes in twentieth century mineral dust burden and the associated impact on radiative forcing". Journal of Geophysical Research: Atmospheres. 119 (23): 13, 526–13, 546. Bibcode:2014JGRD..11913526S. doi:10.1002/2014JD022062. hdl:11858/00-001M-0000-0024-A9A2-C. S2CID 128663108.
  61. ^ Namdari, Soodabeh; Karimi, Neamat; Sorooshian, Armin; Mohammadi, GholamHasan; Sehatkashani, Saviz (2018-01-01). "Impacts of climate and synoptic fluctuations on dust storm activity over the Middle East". Atmospheric Environment. 173: 265–276. Bibcode:2018AtmEn.173..265N. doi:10.1016/j.atmosenv.2017.11.016. ISSN 1352-2310. PMC 6192056. PMID 30344444.
  62. ^ Goudie, Andrew S. (2014-02-01). "Desert dust and human health disorders". Environment International. 63: 101–113. doi:10.1016/j.envint.2013.10.011. ISSN 0160-4120. PMID 24275707.
  63. ^ Hu, Tiantian; Wu, Di; Li, Yaohui; Wang, Chenghai (2017-03-28). "The Effects of Sandstorms on the Climate of Northwestern China". Advances in Meteorology. 2017: e4035609. doi:10.1155/2017/4035609. ISSN 1687-9309.
  64. ^ Wu, Yao; Wen, Bo; Li, Shanshan; Guo, Yuming (2021-06-01). "Sand and dust storms in Asia: a call for global cooperation on climate change". The Lancet Planetary Health. 5 (6): e329–e330. doi:10.1016/S2542-5196(21)00082-6. ISSN 2542-5196. PMID 33915087. S2CID 233460168.
  65. ^ "WAD | World Atlas of Desertification". wad.jrc.ec.europa.eu. Archived from the original on 2019-12-09. Retrieved 2019-11-19.
  66. ^ "How Climate Change Is Spurring Land Conflict in Nigeria". Time. 28 June 2018.
  67. ^ "The battle on the frontline of climate change in Mali". BBC News. 22 January 2019. Archived from the original on 9 October 2021. Retrieved 18 December 2021.
  68. ^ "Farmer-Herder Conflicts on the Rise in Africa". ReliefWeb. 6 August 2018. Archived from the original on 17 April 2021. Retrieved 18 December 2021.
  69. ^ Klausmeier, Christopher (1999). "Regular and irregular patterns in semiarid vegetation". Science. 284 (5421): 1826–1828. doi:10.1126/science.284.5421.1826. PMID 10364553.
  70. ^ (www.dw.com), Deutsche Welle. "Grid of straw squares turns Chinese sand to soil – Environment – DW.COM – 23.06.2011". Archived from the original on 12 June 2020. Retrieved 21 June 2016.
  71. ^ "2010–2020: UN Decade for Deserts and the Fight against Desertification". www.un.org. Retrieved 2023-09-11.
  72. ^ https://www.undp.org/sites/g/files/zskgke326/files/publications/The%20Global%20Drylands%20Initiative,%202001-09%20-%20Challenge%20Paper-%20Poverty%20and%20the%20Drylands.pdf
  73. ^ 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.. Archived 2009-08-09 at the Wayback Machine
  74. ^ Pasternak, Dov; Schlissel, Arnold (2001). Combating desertification with plants. Springer. p. 20. ISBN 978-0-306-46632-8. Archived from the original on 2023-07-30. Retrieved 2016-05-16.
  75. ^ Briassoulis, Helen (2005). Policy integration for complex environmental problems: the example of Mediterranean desertification. Ashgate Publishing. p. 161. ISBN 978-0-7546-4243-5. Archived from the original on 2023-07-30. Retrieved 2016-05-16.
  76. ^ Myers, Norman (29 April 2002). "Environmental refugees: a growing phenomenon of the 21st century". Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences. 357 (1420): 609–613. doi:10.1098/rstb.2001.0953. PMC 1692964. PMID 12028796.
  77. ^ Epule, Terence Epule; Peng, Changhui; Lepage, Laurent (5 February 2014). "Environmental refugees in sub-Saharan Africa: a review of perspectives on the trends, causes, challenges and way forward". GeoJournal. 80: 79–92. doi:10.1007/s10708-014-9528-z. S2CID 154503204.
  78. ^ "Mongolia's nomadic way of life under threat". gulfnews.com. 2018-08-01. Retrieved 2023-10-04.
  79. ^ Stringer, Lindsay C.; Dyer, Jen C.; Reed, Mark S.; Dougill, Andrew J.; Twyman, Chasca; Mkwambisi, David (2009). "Adaptations to climate change, drought and desertification: local insights to enhance policy in southern Africa". Environmental Science & Policy. 12 (7): 748–765. doi:10.1016/j.envsci.2009.04.002.
  80. ^ "Goal 15 targets". UNDP. Archived from the original on 2017-09-04. Retrieved 2020-09-24.
  81. ^ Pasternak, D.; Schlissel, Arnold (2012-12-06). Combating Desertification with Plants. Springer Science & Business Media. p. 38. ISBN 9781461513278.
  82. ^ Drost, Daniel; Long, Gilbert; Wilson, David; Miller, Bruce; Campbell, William (1 December 1996). "Barriers to Adopting Sustainable Agricultural Practices". Journal of Extension. 34 (6). Archived from the original on 22 February 2017. Retrieved 21 February 2017.
  83. ^ Briassoulis, Helen (2005). Policy integration for complex environmental problems: the example of Mediterranean desertification. Ashgate Publishing. p. 237. ISBN 978-0-7546-4243-5.
  84. ^ Techniques for Desert Reclamation by Andrew S. Goudie
  85. ^ Desert reclamation projects Archived 2009-01-03 at the Wayback Machine
  86. ^ "Desertification". USGS. 1997. Archived from the original on 2010-08-02. Retrieved 2006-06-10.
  87. ^ "Drylands Restoration Initiative". Food and Agriculture Organization of the United Nations. Archived from the original on 23 July 2016. Retrieved 14 April 2016.
  88. ^ Global guidelines for the restoration of degraded forests and landscapes in drylands (PDF). Food and Agriculture Organization of the United Nations. June 2015. ISBN 978-92-5-108912-5. Archived (PDF) from the original on 2016-04-23.
  89. ^ "desertification 3D environment". Archived from the original on 2021-02-28. Retrieved 2020-09-25.
  90. ^ "China's 'Great Green Wall' Fights Expanding Desert". 2017-04-21. Archived from the original on 2017-08-13. Retrieved 2017-05-04.
  91. ^ Hui, Lu (May 26, 2018). "Across China: A guardian of the great green wall against China's second largest desert". Xinghua News Agency. Archived from the original on May 26, 2018.
  92. ^ Beiser, Vince (September 1, 2017). "A tree grows in China: can a "Green Great Wall" stop sand from devouring the countryside?". Mother Jones. 83 (4).
  93. ^ Gadzama, Njidda Mamadu (2017). "Attenuation of the effects of desertification through sustainable development of Great Green Wall in the Sahel of Africa". World Journal of Science, Technology and Sustainable Development. 14 (4): 279–289. doi:10.1108/WJSTSD-02-2016-0021.
  94. ^ Jonathan Watts (7 September 2020). "Africa's Great Green Wall just 4% complete halfway through schedule". The Guardian. ISSN 0261-3077. Archived from the original on 6 May 2022. Retrieved 18 December 2021 – via www.theguardian.com.
  95. ^ "Great Green Wall|Action Against Desertification|Food and Agriculture Organization of the United Nations". www.fao.org. Archived from the original on 2022-01-27. Retrieved 2022-02-27.
  96. ^ Gadzama, Njidda (2017). "Attenuation of the Effects of Desertification through Sustainable Development of Great Green Wall in the Sahel of Africa". World Journal of Science, Technology and Sustainable Development. 14 (4): 279–289. doi:10.1108/WJSTSD-02-2016-0021.
  97. ^ United Nations Convention to Combat Desertification (2019). "The Great Green Wall Initiative". United Nations Convention to Combat Desertification. Archived from the original on 2019-12-02. Retrieved 2019-12-03.
  98. ^ "Windbreaks - an overview | ScienceDirect Topics". www.sciencedirect.com. Archived from the original on 2022-02-27. Retrieved 2022-02-27.
  99. ^ "Our Good Earth – National Geographic Magazine". Archived from the original on 25 April 2017. Retrieved 21 June 2016.
  100. ^ "Home – Justdiggit". Archived from the original on 2 April 2016. Retrieved 21 June 2016.
  101. ^ Nefzaoui, Ali (30 January 2014). "Cactus as a Tool to Mitigate Drought and to Combat Desertification". Journal of Arid Land Studies. 24 (1): 121–124. hdl:20.500.11766/7319.
  102. ^ Krah, Kwabena; Michelson, Hope; Perge, Emilie; Jindal, Rohit (1 December 2019). "Constraints to adopting soil fertility management practices in Malawi: A choice experiment approach". World Development. 124: 104651. doi:10.1016/j.worlddev.2019.104651. S2CID 202302505.
  103. ^ Duflo, Esther; Kremer, Michael; Robinson, Jonathan (October 2011). "Nudging Farmers to Use Fertilizer: Theory and Experimental Evidence from Kenya" (PDF). American Economic Review. 101 (6): 2350–2390. doi:10.1257/aer.101.6.2350. hdl:1721.1/63964. Archived (PDF) from the original on 2015-10-02.
  104. ^ "Département Biologie Végétale – Laboratoire Commun de Microbiologie IRD-ISRA-UCAD". Archived from the original on 24 June 2016. Retrieved 21 June 2016.
  105. ^ "Bioengineered soil microbes may help prevent desertification". phys.org. Archived from the original on 2020-08-27. Retrieved 2020-08-26.
  106. ^ Rethinking landscapes, Nicol-André Berdellé July 2011 Archived 2016-08-17 at the Wayback Machine H2O magazine
  107. ^ "Sprouting Trees From the Underground Forest — A Simple Way to Fight Desertification and Climate Change – Water Matters – State of the Planet". Blogs.ei.columbia.edu. 2011-10-18. Archived from the original on 2012-06-23. Retrieved 2012-08-11.
  108. ^ a b c "How fences could save the planet". newstatesman.com. January 13, 2011. Archived from the original on August 14, 2017. Retrieved May 5, 2013.
  109. ^ "Restoring soil carbon can reverse global warming, desertification and biodiversity". mongabay.com. February 21, 2008. Archived from the original on June 25, 2013. Retrieved May 5, 2013.
  110. ^ Abend, Lisa (January 25, 2010). "How eating grass-fed beef could help fight climate change". time.com. Archived from the original on January 17, 2010. Retrieved May 11, 2013.
  111. ^ "Desertification". pubs.usgs.gov. Retrieved 2023-09-11.
  112. ^ Dregne, H.E. "Desertification of Arid Lands". Columbia University. Archived from the original on 28 April 2023. Retrieved 3 December 2013.
  113. ^ Mortimore, Michael (1989). Adapting to drought: farmers, famines, and desertification in West Africa. Cambridge University Press. p. 12. ISBN 978-0-521-32312-3. Archived from the original on 2023-07-30. Retrieved 2016-05-16.

Sources edit

External links edit