desertification

Desertification is a gradual process of increased soil aridity. 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."{{Cite journal |last1=Hulme |first1=Mike |last2=Kelly |first2=Mick |date=1993 |title=Exploring the links between Desertification and Climate Change |url=http://www.tandfonline.com/doi/abs/10.1080/00139157.1993.9929106 |journal=Environment: Science and Policy for Sustainable Development |language=en |volume=35 |issue=6 |pages=4–45 |bibcode=1993ESPSD..35f...4H |doi=10.1080/00139157.1993.9929106 |issn=0013-9157|url-access=subscription }}

Definition of Desert – That area of the earth where the sum of rain and snowfall is much less than other areas, where the annual average rainfall is less than 25CM. Definition by UNO (1995) – Land degradation in barren, humid and sub-humid areas due to climate change and human activities is called desertification.

As of 2005, considerable controversy existed over the proper definition of the term desertification with more than 100 formal definitions in existence.{{Cite book |last=Geist |first=Helmut

|url=https://www.taylorfrancis.com/books/mono/10.4324/9781315240855/causes-progression-desertification-helmut-geist |title=The Causes and Progression of Desertification |date=2017-10-01 |publisher=Routledge |isbn=978-1-315-24085-5 |location=London |doi=10.4324/9781315240855}} 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|date=October 2023}} 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.{{cite encyclopedia

| title = Desertification

| first1 = John P.

| last1 = Rafferty

| first2 = Stuart L.

| last2 = Pimm

| encyclopedia =Encyclopædia Britannica

| url = https://www.britannica.com/science/desertification

| access-date = 2019-11-06

| date = January 26, 2023

| quote = The concept does not refer to the physical expansion of existing deserts but rather to the various processes that threaten all dryland ecosystems.

}}

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".{{Cite journal |last1=Geist |first1=Helmut J. |last2=Lambin |first2=Eric F. |date=2004 |title=Dynamic Causal Patterns of Desertification |journal=BioScience |language=en |volume=54 |issue=9 |pages=817 |doi=10.1641/0006-3568(2004)054[0817:DCPOD]2.0.CO;2 |issn=0006-3568|doi-access=free }}

{{See also|Deforestation#Causes}}

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.{{cite book|author=Geeson, Nichola|title=Mediterranean desertification: a mosaic of processes and responses|publisher=John Wiley & Sons|year=2002|isbn=978-0-470-84448-9|page=58|url=https://books.google.com/books?id=G_0qg0f49GQC&pg=PA58|display-authors=etal|access-date=2016-05-16|archive-date=2023-07-30|archive-url=https://web.archive.org/web/20230730161049/https://books.google.com/books?id=G_0qg0f49GQC&pg=PA58|url-status=live}} 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.

Early studies argued one of the most common causes of desertification was overgrazing, over consumption of vegetation by cattle or other livestock.{{Cite journal |last=Charney |first=J. G. |date=April 1975 |title=Dynamics of deserts and drought in the Sahel |url=https://onlinelibrary.wiley.com/doi/10.1002/qj.49710142802 |journal=Quarterly Journal of the Royal Meteorological Society |language=en |volume=101 |issue=428 |pages=193–202 |doi=10.1002/qj.49710142802 |bibcode=1975QJRMS.101..193C |access-date=2022-05-24 |archive-date=2023-07-30 |archive-url=https://web.archive.org/web/20230730161050/https://rmets.onlinelibrary.wiley.com/doi/10.1002/qj.49710142802 |url-status=live |url-access=subscription }} However, the role of local overexploitation in driving desertification in the recent past is controversial.{{Cite journal |date=2016 |editor-last=Behnke |editor-first=Roy |editor2-last=Mortimore |editor2-first=Michael |title=The End of Desertification? |url=https://doi.org/10.1007/978-3-642-16014-1 |journal=Springer Earth System Sciences |language=en |doi=10.1007/978-3-642-16014-1 |isbn=978-3-642-16013-4 |s2cid=132424053 |issn=2197-9596|url-access=subscription }} 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.{{Cite journal |last=Biasutti |first=Michela |date=July 2019 |title=Rainfall trends in the African Sahel: Characteristics, processes, and causes |journal=WIREs Climate Change |language=en |volume=10 |issue=4 |pages=e591 |doi=10.1002/wcc.591 |issn=1757-7780 |pmc=6617823 |pmid=31341517|bibcode=2019WIRCC..10E.591B }} As a result, changing ocean temperature and reductions in sulfate emissions have caused a re-greening of the region. This has led some scholars to argue that agriculture-induced vegetation loss is a minor factor in desertification.

Human population dynamics have a considerable impact on overgrazing, over-farming and deforestation, as previously acceptable techniques have become unsustainable.{{Cite journal|last1=Epule|first1=Terence Epule|last2=Peng|first2=Changhui|last3=Lepage|first3=Laurent|date=February 2015|title=Environmental refugees in sub-Saharan Africa: a review of perspectives on the trends, causes, challenges and way forward|journal=GeoJournal|volume=80|issue=1|pages=79–92|doi=10.1007/s10708-014-9528-z|bibcode=2015GeoJo..80...79E |s2cid=154503204|issn=0343-2521}}

There are multiple reasons farmers use intensive farming as opposed to extensive farming but the main reason is to maximize yields.{{Cite web |date=2019-08-06 |title=Explainer: Desertification and the role of climate change |url=https://www.carbonbrief.org/explainer-desertification-and-the-role-of-climate-change |url-status=live |archive-url=https://web.archive.org/web/20220210001559/https://www.carbonbrief.org/explainer-desertification-and-the-role-of-climate-change |archive-date=2022-02-10 |access-date=2019-10-22 |website=Carbon Brief |language=en}} 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.{{Cite web |last=Nations |first=United |title=World Day to Combat Desertification and Drought |url=https://www.un.org/en/observances/desertification-day |access-date=2023-09-11 |website=United Nations |language=en}}{{Cite web|url=https://www.britannica.com/topic/intensive-agriculture|title=Intensive agriculture|website=Encyclopedia Britannica|language=en|access-date=2019-11-19|archive-date=2008-06-24|archive-url=https://web.archive.org/web/20080624184604/http://www.britannica.com/eb/article-9042533/intensive-agriculture|url-status=live}}

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.{{Cite journal |last1=Tierney |first1=Jessica E. |last2=Pausata |first2=Francesco S. R. |last3=deMenocal |first3=Peter B. |date=2017-01-06 |title=Rainfall regimes of the Green Sahara |journal=Science Advances |language=en |volume=3 |issue=1 |pages=e1601503 |bibcode=2017SciA....3E1503T |doi=10.1126/sciadv.1601503 |issn=2375-2548 |pmc=5242556 |pmid=28116352}} 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.{{Cite journal |last1=Pausata |first1=Francesco S. R. |last2=Messori |first2=Gabriele |last3=Zhang |first3=Qiong |date=2016-01-15 |title=Impacts of dust reduction on the northward expansion of the African monsoon during the Green Sahara period |journal=Earth and Planetary Science Letters |language=en |volume=434 |pages=298–307 |bibcode=2016E&PSL.434..298P |doi=10.1016/j.epsl.2015.11.049 |issn=0012-821X |doi-access=free}} 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.{{cite journal |last1=K. Wright |first1=David |last2=Rull |first2=Valenti |last3=Roberts |first3=Richard |last4=Marchant |first4=Rob |last5=Gil-Romera |first5=Graciela |date=26 January 2017 |title=Humans as Agents in the Termination of the African Humid Period |journal=Frontiers in Earth Science |volume=5 |pages=4 |bibcode=2017FrEaS...5....4W |doi=10.3389/feart.2017.00004 |doi-access=free}}

{{See also|Effects of climate change on the water cycle|Effects of climate change on biomes}}

Research into desertification is complex, and there is no single metric which can define all aspects. However, more intense climate change is still expected to increase the current extent of drylands on the Earth's continents: from 38% in late 20th century to 50% or 56% by the end of the century, under the "moderate" and high-warming Representative Concentration Pathways 4.5 and 8.5. Most of the expansion will be seen over regions such as "southwest North America, the northern fringe of Africa, southern Africa, and Australia".

Drylands cover 41% of the earth's land surface and include 45% of the world's agricultural land.{{Cite journal |last1=Burrell |first1=A. L. |last2=Evans |first2=J. P. |last3=De Kauwe |first3=M. G. |date=2020 |title=Anthropogenic climate change has driven over 5 million km2 of drylands towards desertification |journal=Nature Communications |language=en |volume=11 |issue=1 |page=3853 |doi=10.1038/s41467-020-17710-7 |issn=2041-1723 |pmc=7395722 |pmid=32737311 |doi-access=free}} 50px Text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License] These regions are among the most vulnerable ecosystems to anthropogenic climate and land use change and are under threat of desertification. An observation-based attribution study of desertification was carried out in 2020 which accounted for climate change, climate variability, CO₂ fertilization as well as both the gradual and rapid ecosystem changes caused by land use. The study found that, between 1982 and 2015, 6% of the world's drylands underwent desertification driven by unsustainable land use practices compounded by anthropogenic climate change. Despite an average global greening, anthropogenic climate change has degraded 12.6% (5.43 million km²) of drylands, contributing to desertification and affecting 213 million people, 93% of who live in developing economies.

File:SHB-Red-Dust.jpg covered in dust]]

There has been a 25% increase in global annual dust emissions between the late nineteenth century to present day.{{Cite journal |last1=Stanelle |first1=Tanja |last2=Bey |first2=Isabelle |last3=Raddatz |first3=Thomas |last4=Reick |first4=Christian |last5=Tegen |first5=Ina |date=2014-12-16 |title=Anthropogenically induced changes in twentieth century mineral dust burden and the associated impact on radiative forcing |journal=Journal of Geophysical Research: Atmospheres |language=en |volume=119 |issue=23 |pages=13,526–13,546 |bibcode=2014JGRD..11913526S |doi=10.1002/2014JD022062 |s2cid=128663108 |hdl-access=free |hdl=11858/00-001M-0000-0024-A9A2-C}} 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”.{{Cite journal |last1=Namdari |first1=Soodabeh |last2=Karimi |first2=Neamat |last3=Sorooshian |first3=Armin |last4=Mohammadi |first4=GholamHasan |last5=Sehatkashani |first5=Saviz |date=2018-01-01 |title=Impacts of climate and synoptic fluctuations on dust storm activity over the Middle East |journal=Atmospheric Environment |volume=173 |pages=265–276 |bibcode=2018AtmEn.173..265N |doi=10.1016/j.atmosenv.2017.11.016 |issn=1352-2310 |pmc=6192056 |pmid=30344444}}

Dust storms can contribute to certain respiratory disorders such as pneumonia, skin irritations, asthma and many more.{{Cite journal |last=Goudie |first=Andrew S. |date=2014-02-01 |title=Desert dust and human health disorders |journal=Environment International |volume=63 |pages=101–113 |doi=10.1016/j.envint.2013.10.011 |issn=0160-4120 |pmid=24275707|bibcode=2014EnInt..63..101G }} 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.{{Cite journal |last1=Hu |first1=Tiantian |last2=Wu |first2=Di |last3=Li |first3=Yaohui |last4=Wang |first4=Chenghai |date=2017-03-28 |title=The Effects of Sandstorms on the Climate of Northwestern China |journal=Advances in Meteorology |language=en |volume=2017 |pages=e4035609 |doi=10.1155/2017/4035609 |issn=1687-9309 |doi-access=free}}{{Cite journal |last1=Wu |first1=Yao |last2=Wen |first2=Bo |last3=Li |first3=Shanshan |last4=Guo |first4=Yuming |date=2021-06-01 |title=Sand and dust storms in Asia: a call for global cooperation on climate change |journal=The Lancet Planetary Health |language=English |volume=5 |issue=6 |pages=e329–e330 |doi=10.1016/S2542-5196(21)00082-6 |issn=2542-5196 |pmid=33915087 |s2cid=233460168 |doi-access=free}} 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.

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.{{Cite web |title=WAD {{!}} World Atlas of Desertification |url=https://wad.jrc.ec.europa.eu/globalagriculture |url-status=live |archive-url=https://web.archive.org/web/20191209170553/https://wad.jrc.ec.europa.eu/globalagriculture |archive-date=2019-12-09 |access-date=2019-11-19 |website=wad.jrc.ec.europa.eu}} 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.{{cite magazine |date=28 June 2018 |title=How Climate Change Is Spurring Land Conflict in Nigeria |url=https://time.com/5324712/climate-change-nigeria/ |magazine=Time}}{{cite news |date=22 January 2019 |title=The battle on the frontline of climate change in Mali |work=BBC News |url=https://www.bbc.com/news/the-reporters-46921487 |url-status=live |access-date=18 December 2021 |archive-url=https://web.archive.org/web/20211009175946/https://www.bbc.com/news/the-reporters-46921487 |archive-date=9 October 2021}}{{cite news |date=6 August 2018 |title=Farmer-Herder Conflicts on the Rise in Africa |publisher=ReliefWeb |url=https://reliefweb.int/report/world/farmer-herder-conflicts-rise-africa |url-status=live |access-date=18 December 2021 |archive-url=https://web.archive.org/web/20210417045057/https://reliefweb.int/report/world/farmer-herder-conflicts-rise-africa |archive-date=17 April 2021}}

File:Soil erosion, Southfield - geograph.org.uk - 367917.jpg outside Leuchars]]

At least 90% of the inhabitants of drylands live in developing countries, where they also suffer from poor economic and social conditions.{{Cite web |title=2010–2020: UN Decade for Deserts and the Fight against Desertification |url=https://www.un.org/en/events/desertification_decade/index.shtml |access-date=2023-09-11 |website=www.un.org |language=EN}} 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.[https://www.undp.org/sites/g/files/zskgke326/files/publications/The%20Global%20Drylands%20Initiative,%202001-09%20-%20Challenge%20Paper-%20Poverty%20and%20the%20Drylands.pdf Poverty and the Drylands] undp.org

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.{{Cite web|url=http://www.csf-desertification.org/index.php/bibliotheque/doc_details/119-cornet-antoine-2002-desertification-and-its-relationship-to-the-environment-and-development|archive-url=https://web.archive.org/web/20090809142606/http://www.csf-desertification.org/index.php/bibliotheque/doc_details/119-cornet-antoine-2002-desertification-and-its-relationship-to-the-environment-and-development|url-status=dead|title=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..|archive-date=9 August 2009}}

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.{{cite book|author=Pasternak, Dov|author2=Schlissel, Arnold|title=Combating desertification with plants|publisher=Springer|year=2001|isbn=978-0-306-46632-8|page=20|url=https://books.google.com/books?id=B-i8-DPf6xgC&pg=PA20|access-date=2016-05-16|archive-date=2023-07-30|archive-url=https://web.archive.org/web/20230730161050/https://books.google.com/books?id=B-i8-DPf6xgC&pg=PA20|url-status=live}}{{cite book|author=Briassoulis, Helen|title=Policy integration for complex environmental problems: the example of Mediterranean desertification|publisher=Ashgate Publishing|year=2005|isbn=978-0-7546-4243-5|page=161|url=https://books.google.com/books?id=CpYnV45hVRsC&pg=PA161|access-date=2016-05-16|archive-date=2023-07-30|archive-url=https://web.archive.org/web/20230730161052/https://books.google.com/books?id=CpYnV45hVRsC&pg=PA161|url-status=live}} 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.{{cite journal |last1=Myers |first1=Norman |date=29 April 2002 |title=Environmental refugees: a growing phenomenon of the 21st century |journal=Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences |volume=357 |issue=1420 |pages=609–613 |doi=10.1098/rstb.2001.0953 |pmc=1692964 |pmid=12028796}}{{cite journal |last1=Epule |first1=Terence Epule |last2=Peng |first2=Changhui |last3=Lepage |first3=Laurent |date=5 February 2014 |title=Environmental refugees in sub-Saharan Africa: a review of perspectives on the trends, causes, challenges and way forward |journal=GeoJournal |volume=80 |issue=1 |pages=79–92 |doi=10.1007/s10708-014-9528-z |bibcode=2015GeoJo..80...79E |s2cid=154503204}}

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.{{Cite web |date=2018-08-01 |title=Mongolia's nomadic way of life under threat |url=https://gulfnews.com/lifestyle/mongolias-nomadic-way-of-life-under-threat-1.2259998 |access-date=2023-10-04 |website=gulfnews.com |language=en}}

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.{{Cite journal|last1=Stringer|first1=Lindsay C.|last2=Dyer|first2=Jen C.|last3=Reed|first3=Mark S.|last4=Dougill|first4=Andrew J.|last5=Twyman|first5=Chasca|last6=Mkwambisi|first6=David|title=Adaptations to climate change, drought and desertification: local insights to enhance policy in southern Africa|journal=Environmental Science & Policy|volume=12|issue=7|pages=748–765|doi=10.1016/j.envsci.2009.04.002|year=2009|bibcode=2009ESPol..12..748S }}

There is, however, increased global advocacy e.g. the UN SDG 15{{Cite web |title=Goal 15 targets |url=https://www.undp.org/content/undp/en/home/sustainable-development-goals/goal-15-life-on-land/targets.html |url-status=dead |archive-url=https://web.archive.org/web/20170904001634/https://www.undp.org/content/undp/en/home/sustainable-development-goals/goal-15-life-on-land/targets.html |archive-date=2017-09-04 |access-date=2020-09-24 |website=UNDP |language=en}} to combat desertification and restore affected lands.

Drylands occupy approximately 40–41% of Earth's land area and are home to more than 2 billion people.{{Cite book |title=Governing global desertification: linking environmental degradation, poverty and participation |date=2006 |publisher=Ashgate [u.a.] |isbn=978-0-7546-4359-3 |editor-last=Johnson |editor-first=Pierre-Marc |series=Global environmental governance series |location=Aldershot |editor-last2=Johnson |editor-first2=Pierre Marc}} 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.{{cite web |date=10 October 2017 |title=UNCCD: Impact and role of drylands |url=https://www.unccd.int/un-decade-deserts-and-fight-against-desertification-impact-and-role-drylands |url-status=dead |archive-url=https://web.archive.org/web/20191107121026/https://www.unccd.int/un-decade-deserts-and-fight-against-desertification-impact-and-role-drylands |archive-date=7 November 2019 |access-date=7 November 2019 |website=UNCCD}}{{cite book |author=World Bank |url=https://books.google.com/books?id=XxBrq6hTs_UC&pg=PA454 |title=Gender in agriculture sourcebook |publisher=World Bank Publications |year=2009 |isbn=978-0-8213-7587-7 |page=454 |access-date=2016-05-16 |archive-url=https://web.archive.org/web/20230730160546/https://books.google.com/books?id=XxBrq6hTs_UC&pg=PA454 |archive-date=2023-07-30 |url-status=live}}

{{Further|Sahel#Desertification and soil loss}}

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).{{Cite journal |last=Nicholson |first=Sharon E. |date=2013-02-17 |title=The West African Sahel: A Review of Recent Studies on the Rainfall Regime and Its Interannual Variability |journal=International Scholarly Research Notices |language=en |volume=2013 |pages=e453521 |doi=10.1155/2013/453521 |doi-access=free}} So, droughts are the rule in the Sahel region.{{Cite web |last=Riebeek |first=Holli |date=2007-01-03 |title=Defining Desertification : Feature Articles |url=http://earthobservatory.nasa.gov/Features/Desertification/desertification2.php |url-status=live |archive-url=https://web.archive.org/web/20161201211259/http://earthobservatory.nasa.gov/Features/Desertification/desertification2.php |archive-date=2016-12-01 |access-date=2016-11-30 |website=earthobservatory.nasa.gov}} The Sahel has lost approximately 650,000 km² of its productive agricultural land over the past 50 years;[https://www.thegeographeronline.net/uploads/2/6/6/2/26629356/a116_sahel.pdf Environmental issues in the Sahel] Geo Factsheet the propagation of desertification in this area is considerable.{{cite journal |last1=Nicholson |first1=S. E. |last2=Tucker |first2=C. J. |last3=Ba |first3=M. B. |date=1 May 1998 |title=Desertification, Drought, and Surface Vegetation: An Example from the West African Sahel |journal=Bulletin of the American Meteorological Society |volume=79 |issue=5 |pages=815–830 |bibcode=1998BAMS...79..815N |doi=10.1175/1520-0477(1998)079<0815:DDASVA>2.0.CO;2 |doi-access=free}}{{Cite web |title=Land Resource Stresses and Desertification in Africa |url=https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/use/?cid=nrcs142p2_054025 |url-status=dead |archive-url=https://web.archive.org/web/20220401055308/https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/use/?cid=nrcs142p2_054025 |archive-date=1 April 2022 |access-date=24 November 2020 |website=United States Department of Agriculture}}

File:Village Telly in Mali.jpg region of Mali]]

The climate of the Sahara has undergone enormous variations over the last few hundred thousand years,{{Cite journal |author1=Kevin White |author2=David J. Mattingly |year=2006 |title=Ancient Lakes of the Sahara |journal=American Scientist |volume=94 |issue=1 |pages=58–65 |doi=10.1511/2006.57.983}} oscillating between wet (grassland) and dry (desert) every 20,000 years{{cite news |author=Jennifer Chu |date=January 2, 2019 |title=A "pacemaker" for North African climate |url=http://news.mit.edu/2019/study-regulating-north-african-climate-0102 |url-status=live |archive-url=https://web.archive.org/web/20220115093627/https://news.mit.edu/2019/study-regulating-north-african-climate-0102 |archive-date=January 15, 2022 |access-date=January 20, 2020 |publisher=MIT News}} (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 40,000-year cycle in which the axial tilt of the earth changes between 22° and 24.5°).{{cite book |last1=Houérou |first1=Henry N. |url=https://books.google.com/books?id=_Rvs7NkfeLEC&q=Sahara+rainfall+virtually+zero&pg=PA16 |title=Bioclimatology and Biogeography of Africa |date=2008-12-10 |publisher=Springer Science & Business Media |isbn=978-3-540-85192-9 |language=en |access-date=2020-12-11 |archive-url=https://web.archive.org/web/20230730160547/https://books.google.com/books?id=_Rvs7NkfeLEC&q=Sahara+rainfall+virtually+zero&pg=PA16 |archive-date=2023-07-30 |url-status=live}} 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.{{cite web |author=Christian Bouquet |date=December 2017 |title=Le Sahara entre ses deux rives. Éléments de délimitation par la géohistoire d'un espace de contraintes |url=http://geoconfluences.ens-lyon.fr/informations-scientifiques/dossiers-regionaux/afrique-dynamiques-regionales/articles-scientifiques/sahara-entre-deux-rives |url-status=live |archive-url=https://web.archive.org/web/20220210001607/http://geoconfluences.ens-lyon.fr/informations-scientifiques/dossiers-regionaux/afrique-dynamiques-regionales/articles-scientifiques/sahara-entre-deux-rives |archive-date=2022-02-10 |access-date=2018-01-25 |website=Géoconfluences |quote=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.}}

Lake Chad, located in the Sahel region, has undergone desiccation due to water withdrawal for irrigation and decrease in rainfall.{{cite journal |last1=Okpara |first1=Uche T. |last2=Stringer |first2=Lindsay C. |last3=Dougill |first3=Andrew J. |date=November 2016 |title=Lake drying and livelihood dynamics in Lake Chad: Unravelling the mechanisms, contexts and responses |journal=Ambio |volume=45 |issue=7 |pages=781–795 |bibcode=2016Ambio..45..781O |doi=10.1007/s13280-016-0805-6 |pmc=5055484 |pmid=27371137}} The lake has shrunk by over 90% since 1987, displacing millions of inhabitants.{{Cite web |last=Jiang |first=Ingrid |date=2022-08-12 |title=A Remarkable Size Shrinking in Lake Chad |url=https://storymaps.arcgis.com/stories/e63a90f8552d4e5f98f4c56a56c06f9d |access-date=2023-09-22 |website=ArcGIS StoryMaps |language=en-ca}} Recent efforts have managed to make some progress toward its restoration, but it is still considered to be at risk of disappearing entirely.{{cite journal |last1=Onamuti |first1=Olapeju Y. |last2=Okogbue |first2=Emmanuel C. |last3=Orimoloye |first3=Israel R. |date=8 November 2017 |title=Remote sensing appraisal of Lake Chad shrinkage connotes severe impacts on green economics and socio-economics of the catchment area |journal=Royal Society Open Science |volume=4 |issue=11 |pages=171120 |doi=10.1098/rsos.171120 |pmc=5717671 |pmid=29291097}}

To limit desertification, the Great Green Wall (Africa) initiative was started in 2007 involving the planting of vegetation along a stretch of 7,775 km, 15 km wide, involving 22 countries to 2030.{{Cite web |title=Great Green Wall Initiative |url=https://www.unccd.int/our-work/ggwi |access-date=2023-09-22 |website=UNCCD |language=en}} 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.{{cite web |title=The Great Green Wall | National Geographic Society |url=https://education.nationalgeographic.org/resource/great-green-wall/ |url-status=live |archive-url=https://web.archive.org/web/20221222164123/https://education.nationalgeographic.org/resource/great-green-wall/ |archive-date=2022-12-22 |access-date=2022-12-22}}

{{See also|Environmental issues in Mongolia#Desertification}}

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 {{convert|3600|km2|sqmi|abbr=off}} of grassland into wasteland annually.{{Cite web |last=Rechtschaffen |first=Daniel |title=How China's Growing Deserts Are Choking The Country |url=https://www.forbes.com/sites/danielrechtschaffen/2017/09/18/how-chinas-growing-deserts-are-choking-the-country/ |url-status=live |archive-url=https://web.archive.org/web/20220216110308/https://www.forbes.com/sites/danielrechtschaffen/2017/09/18/how-chinas-growing-deserts-are-choking-the-country/ |archive-date=2022-02-16 |access-date=2022-08-28 |website=Forbes |language=en}} 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.{{cite report |url=http://www.geo.utexas.edu/courses/371c/project/2009/Welker_Desertification.pdf |title=The Desertification of the Gobi Desert and Its Effect on Beijing |last=Welker |first=Lauren |date=2009 |publisher=University of Texas-Austin School of Geosciences |archive-url=https://web.archive.org/web/20140124101958/http://www.geo.utexas.edu/courses/371c/project/2009/Welker_Desertification.pdf |archive-date=2014-01-24 |url-status=live |type=Unpublished manuscript}}{{Cite web |date=2020-03-25 |title=Gobi Desert: A Complete Guide to East Asia's Largest Desert |url=https://www.youngpioneertours.com/gobi-desert-guide/ |url-status=live |archive-url=https://web.archive.org/web/20230730160548/https://www.youngpioneertours.com/gobi-desert-guide/ |archive-date=2023-07-30 |access-date=2022-04-03 |website=Young Pioneer Tours |language=en}}

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.{{Cite web |title=What Is Desertification and How Does It Impact Mongolia? |url=https://breathemongolia.org/en/news-article/desertification-impact-mongolia/ |url-status=live |archive-url=https://web.archive.org/web/20220401180828/https://breathemongolia.org/en/news-article/desertification-impact-mongolia |archive-date=2022-04-01 |access-date=2022-04-03 |website=Breathe Mongolia – English |language=en-US}}{{Cite journal |last1=Han |first1=Jie |last2=Dai |first2=Han |last3=Gu |first3=Zhaolin |date=2021-12-01 |title=Sandstorms and desertification in Mongolia, an example of future climate events: a review |url=https://doi.org/10.1007/s10311-021-01285-w |url-status=live |journal=Environmental Chemistry Letters |language=en |volume=19 |issue=6 |pages=4063–4073 |bibcode=2021EnvCL..19.4063H |doi=10.1007/s10311-021-01285-w |issn=1610-3661 |pmc=8302971 |pmid=34335128 |archive-url=https://web.archive.org/web/20230730160551/https://link.springer.com/article/10.1007/s10311-021-01285-w |archive-date=2023-07-30 |access-date=2022-04-03}} During the period 1940 to 2015, the mean air temperature increased by 2.24 °C.{{Cite journal |last1=Han |first1=Jie |last2=Dai |first2=Han |last3=Gu |first3=Zhaolin |date=2021-12-01 |title=Sandstorms and desertification in Mongolia, an example of future climate events: a review |url=https://doi.org/10.1007/s10311-021-01285-w |journal=Environmental Chemistry Letters |language=en |volume=19 |issue=6 |pages=4063–4073 |bibcode=2021EnvCL..19.4063H |doi=10.1007/s10311-021-01285-w |issn=1610-3661 |pmc=8302971 |pmid=34335128}} 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.[https://www.adb.org/sites/default/files/publication/31145/making-grasslands-sustainable-mongolia.pdf Making Grasslands Sustainable in Mongolia] adb.org In addition, the Mongolia government has listed forest fires, blights, unsustainable forestry and mining activities as leading causes of desertification in the country.[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 Report] unep.org 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.{{Citation |last1=Dorj |first1=O. |title=Mongolia: Country Features, the Main Causes of Desertification and Remediation Efforts |date=2013 |work=Combating Desertification in Asia, Africa and the Middle East |pages=217–229 |editor-last=Heshmati |editor-first=G. Ali |place=Dordrecht |publisher=Springer Netherlands |language=en |doi=10.1007/978-94-007-6652-5_11 |isbn=978-94-007-6651-8 |last2=Enkhbold |first2=M. |last3=Lkhamyanjin |first3=S. |last4=Mijiddorj |first4=Kh. |last5=Nosmoo |first5=A. |last6=Puntsagnamil |first6=M. |last7=Sainjargal |first7=U. |editor2-last=Squires |editor2-first=Victor R.}}

To mitigate the financial impact of desertification in Inner Mongolia, Bai Jingying teaches women how to do traditional embroidery, which they then sell to provide additional income.{{Cite web |title=Community threads together |url=https://www.chinadailyhk.com/hk/article/252552#Community-threads-together-2021-12-20 |access-date=2024-07-14 |website=chinadailyhk |language=en}}

{{excerpt|Gobi Desert#Desertification}}

South America is another area vulnerable by desertification, as 25% of the land is classified as drylands{{Cite web |date=16 June 2016 |title=Soil Degradation Threatens Nutrition in Latin America - World |url=https://reliefweb.int/report/world/soil-degradation-threatens-nutrition-latin-america |url-status=live |archive-url=https://web.archive.org/web/20220403121753/https://reliefweb.int/report/world/soil-degradation-threatens-nutrition-latin-america |archive-date=2022-04-03 |access-date=2022-04-03 |website=ReliefWeb |language=en}} and over 68% of the land area has undergone soil erosion as a result of deforestation and overgrazing.{{Cite web |date=2018-06-15 |title=Why We Should Invest in Land Management in Latin America |url=https://www.nrdc.org/bio/carolina-herrera/why-we-should-invest-land-management-latin-america |access-date=2023-09-25 |website=www.nrdc.org |language=en}} 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 1,000 km² of land have been lost yearly due to desertification. In Argentina, desertification has the potential to disrupt the nation's food supply.{{cite journal |last1=Torres |first1=Laura |last2=Abraham |first2=Elena M. |last3=Rubio |first3=Clara |last4=Barbero-Sierra |first4=Celia |last5=Ruiz-Pérez |first5=Manuel |date=7 July 2015 |title=Desertification Research in Argentina |journal=Land Degradation & Development |volume=26 |issue=5 |pages=433–440 |bibcode=2015LDeDe..26..433T |doi=10.1002/ldr.2392 |s2cid=129476957 |hdl-access=free |hdl=11336/48401}}

{{See also|Deforestation#Control}}

File:Harsh Vardhan addressing at the inauguration of the United Nations Convention to Combat Desertification (UNCCD) Asia-Pacific four-day Regional Workshop, in New Delhi (1).JPG related to the United Nations Convention to Combat Desertification]]

File:North Sahara. Anti-sand shields.jpg, Tunisia]]

File:GreeningdesertTharIndia.jpg plantations, such as those shown, have played a role in combating edge effects of desertification in the Thar Desert, India.{{cite book|last1=Pasternak|first1=D.|last2=Schlissel|first2=Arnold|title=Combating Desertification with Plants|publisher=Springer Science & Business Media|isbn=9781461513278|page=38|url=https://books.google.com/books?id=6XfgBwAAQBAJ&pg=PA38|date=2012-12-06}}]]

File:Tamarisk planted along roads in Xinjiang near Cherchen to slow desertification.jpg planted along roads in Xinjiang near Cherchen to slow desertification]]

Techniques and countermeasures exist for mitigating or reversing desertification. For some of these measures, 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.{{cite journal|last1=Drost|first1=Daniel|last2=Long|first2=Gilbert|last3=Wilson|first3=David|last4=Miller|first4=Bruce|last5=Campbell|first5=William|title=Barriers to Adopting Sustainable Agricultural Practices|issue=6|url=https://www.joe.org/joe/1996december/a1.php|journal=Journal of Extension|volume=34|date=1 December 1996|access-date=21 February 2017|archive-date=22 February 2017|archive-url=https://web.archive.org/web/20170222053123/https://www.joe.org/joe/1996december/a1.php|url-status=dead}} Another issue is a lack of political will, and lack of funding to support land reclamation and anti-desertification programs.{{cite book|author=Briassoulis, Helen|title=Policy integration for complex environmental problems: the example of Mediterranean desertification|publisher=Ashgate Publishing|year=2005|isbn=978-0-7546-4243-5|page=237|url=https://books.google.com/books?id=CpYnV45hVRsC&pg=PA237}}

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.Techniques for Desert Reclamation by Andrew S. Goudie{{Cite web|url=http://www.gsafweb.org/TrusteeNews/desertdevelopmen.html|archive-url=https://web.archive.org/web/20090103172821/http://www.gsafweb.org/TrusteeNews/desertdevelopmen.html|url-status=dead|title=Desert reclamation projects|archive-date=3 January 2009}}

{{Main|Soil regeneration}}

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.

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.{{cite web|url=http://ngm.nationalgeographic.com/2008/09/soil/mann-text.html|title=Our Good Earth – National Geographic Magazine|access-date=21 June 2016|archive-date=25 April 2017|archive-url=https://web.archive.org/web/20170425181742/http://ngm.nationalgeographic.com/2008/09/soil/mann-text.html|url-status=dead}}

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.{{cite web|url=http://nagafoundation.org/|title=Home – Justdiggit|access-date=21 June 2016|archive-url=https://web.archive.org/web/20160402205707/https://nagafoundation.org/|archive-date=2 April 2016|url-status=dead}}

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),{{cite journal |last1=Nefzaoui |first1=Ali |title=Cactus as a Tool to Mitigate Drought and to Combat Desertification |journal=Journal of Arid Land Studies |volume=24 |issue=1 |date=30 January 2014 |pages=121–124 |hdl=20.500.11766/7319 |hdl-access=free }} 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.{{cite journal |last1=Krah |first1=Kwabena |last2=Michelson |first2=Hope |last3=Perge |first3=Emilie |last4=Jindal |first4=Rohit |title=Constraints to adopting soil fertility management practices in Malawi: A choice experiment approach |journal=World Development |volume=124 |pages=104651 |doi=10.1016/j.worlddev.2019.104651 |date=1 December 2019|s2cid=202302505 }} Several nations, including India, Zambia, and Malawi have responded to this by implementing subsidies to help encourage adoption of this technique.{{cite journal |last1=Duflo |first1=Esther |last2=Kremer |first2=Michael |last3=Robinson |first3=Jonathan |title=Nudging Farmers to Use Fertilizer: Theory and Experimental Evidence from Kenya |journal=American Economic Review |volume=101 |issue=6 |pages=2350–2390 |doi=10.1257/aer.101.6.2350 |date=October 2011|url=http://www.nber.org/papers/w15131.pdf |archive-url=https://web.archive.org/web/20151002053100/http://www.nber.org/papers/w15131.pdf |archive-date=2015-10-02 |url-status=live |hdl=1721.1/63964 |hdl-access=free }}

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).{{cite web|url=http://196.1.95.4/fst/biologie-vegetale/labo_commun.htm|title=Département Biologie Végétale – Laboratoire Commun de Microbiologie IRD-ISRA-UCAD|access-date=21 June 2016|archive-date=24 June 2016|archive-url=https://web.archive.org/web/20160624015819/http://196.1.95.4/fst/biologie-vegetale/labo_commun.htm|url-status=dead}}

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.{{Cite web|title=Bioengineered soil microbes may help prevent desertification|url=https://phys.org/news/2020-08-bioengineered-soil-microbes-desertification.html|access-date=2020-08-26|website=phys.org|language=en|archive-date=2020-08-27|archive-url=https://web.archive.org/web/20200827204631/https://phys.org/news/2020-08-bioengineered-soil-microbes-desertification.html|url-status=live}}

{{Main|Desert greening}}

{{See also|Afforestation}}

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.[http://www.prototype-creation.de/rethinking_landscapes.pdf Rethinking landscapes, Nicol-André Berdellé July 2011] {{Webarchive|url=https://web.archive.org/web/20160817063318/http://www.prototype-creation.de/rethinking_landscapes.pdf |date=2016-08-17 }} H2O magazine

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.{{cite web |url=http://blogs.ei.columbia.edu/2011/10/18/sprouting-trees-from-the-underground-forest-a-simple-way-to-fight-desertification-and-climate-change/ |title=Sprouting Trees From the Underground Forest — A Simple Way to Fight Desertification and Climate Change – Water Matters – State of the Planet |publisher=Blogs.ei.columbia.edu |date=2011-10-18 |access-date=2012-08-11 |archive-date=2012-06-23 |archive-url=https://web.archive.org/web/20120623022554/http://blogs.ei.columbia.edu/2011/10/18/sprouting-trees-from-the-underground-forest-a-simple-way-to-fight-desertification-and-climate-change/ |url-status=live }}

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.{{cite web |title=Drylands Restoration Initiative |url=http://www.fao.org/forestry/aridzone/restoration/en/ |url-status=live |archive-url=https://web.archive.org/web/20160723220152/http://www.fao.org/forestry/aridzone/restoration/en/ |archive-date=23 July 2016 |access-date=14 April 2016 |publisher=Food and Agriculture Organization of the United Nations}} 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.{{cite book |url=http://www.fao.org/3/a-i5036e.pdf |title=Global guidelines for the restoration of degraded forests and landscapes in drylands |date=June 2015 |publisher=Food and Agriculture Organization of the United Nations |isbn=978-92-5-108912-5 |archive-url=https://web.archive.org/web/20160423203240/http://www.fao.org/3/a-i5036e.pdf |archive-date=2016-04-23 |url-status=live}}

The "Green Wall of China" is a high-profile example of one method that has been finding success in this battle with desertification.{{Cite web |title=desertification 3D environment |url=https://b2b.partcommunity.com/community/knowledge/en/detail/9815/Desertification#knowledge_article |url-status=live |archive-url=https://web.archive.org/web/20210228141238/https://b2b.partcommunity.com/community/knowledge/en/detail/9815/Desertification#knowledge_article |archive-date=2021-02-28 |access-date=2020-09-25}} 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.{{Cite web |date=2017-04-21 |title=China's 'Great Green Wall' Fights Expanding Desert |url=http://news.nationalgeographic.com/2017/04/china-great-green-wall-gobi-tengger-desertification/ |url-status=dead |archive-url=https://web.archive.org/web/20170813110737/http://news.nationalgeographic.com/2017/04/china-great-green-wall-gobi-tengger-desertification/ |archive-date=2017-08-13 |access-date=2017-05-04}} The green wall of China has decreased desert land in China by an annual average of 1,980 square km.{{Cite news |last=Hui |first=Lu |date=May 26, 2018 |title=Across China: A guardian of the great green wall against China's second largest desert |url=http://www.xinhuanet.com/english/2018-05/26/c_137207841.htm |url-status=dead |archive-url=https://web.archive.org/web/20180526094225/http://www.xinhuanet.com/english/2018-05/26/c_137207841.htm |archive-date=May 26, 2018 |work=Xinghua News Agency}} The frequency of sandstorms nationwide have fallen 20% due to the green wall.{{Cite journal |last=Beiser |first=Vince |date=September 1, 2017 |title=A tree grows in China: can a "Green Great Wall" stop sand from devouring the countryside? |journal=Mother Jones |volume=83 |issue=4}} 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.{{Cite journal |last=Gadzama |first=Njidda Mamadu |date=2017 |title=Attenuation of the effects of desertification through sustainable development of Great Green Wall in the Sahel of Africa |journal=World Journal of Science, Technology and Sustainable Development |volume=14 |issue=4 |pages=279–289 |doi=10.1108/WJSTSD-02-2016-0021}}

File:Great green wall map.svg, participating countries and Sahel. In September 2020, it was reported that the GGW had covered only 4% of the planned area.{{cite news |author=Jonathan Watts |date=7 September 2020 |title=Africa's Great Green Wall just 4% complete halfway through schedule |url=https://www.theguardian.com/environment/2020/sep/07/africa-great-green-wall-just-4-complete-over-halfway-through-schedule |url-status=live |archive-url=https://web.archive.org/web/20220506222825/https://www.theguardian.com/environment/2020/sep/07/africa-great-green-wall-just-4-complete-over-halfway-through-schedule |archive-date=6 May 2022 |access-date=18 December 2021 |newspaper=The Guardian |via=www.theguardian.com |issn=0261-3077}}]]

In 2007 the African Union started the Great Green Wall of Africa project in order to combat desertification in 20 countries.{{Cite web |title=Great Green Wall{{!}}Action Against Desertification{{!}}Food and Agriculture Organization of the United Nations |url=https://www.fao.org/in-action/action-against-desertification/overview/great-green-wall/en/ |url-status=live |archive-url=https://web.archive.org/web/20220127153831/https://www.fao.org/in-action/action-against-desertification/overview/great-green-wall/en/ |archive-date=2022-01-27 |access-date=2022-02-27 |website=www.fao.org}} 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{{nbsp}}million{{nbsp}}hectares of land, and by 2030 the initiative plans to restore a total of 100 million{{nbsp}}hectares.{{Cite journal |last=Gadzama |first=Njidda |date=2017 |title=Attenuation of the Effects of Desertification through Sustainable Development of Great Green Wall in the Sahel of Africa |journal=World Journal of Science, Technology and Sustainable Development |volume=14 |issue=4 |pages=279–289 |doi=10.1108/WJSTSD-02-2016-0021}} The Great Green Wall has created many job opportunities for the participating countries, with over 20,000 jobs created in Nigeria alone.{{Cite web |last=United Nations Convention to Combat Desertification |date=2019 |title=The Great Green Wall Initiative |url=https://www.unccd.int/actions/great-green-wall-initiative |url-status=live |archive-url=https://web.archive.org/web/20191202120122/https://www.unccd.int/actions/great-green-wall-initiative |archive-date=2019-12-02 |access-date=2019-12-03 |website=United Nations Convention to Combat Desertification}}

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.{{cite news|url=http://www.newstatesman.com/environment/2011/01/lovell-carbon-ward-climate|title=How fences could save the planet|publisher=newstatesman.com|access-date=May 5, 2013|date=January 13, 2011|archive-date=August 14, 2017|archive-url=https://web.archive.org/web/20170814221316/http://www.newstatesman.com/environment/2011/01/lovell-carbon-ward-climate|url-status=live}} 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.{{cite news|url=http://news.mongabay.com/2008/0221-soil_carbon_lovell_interview.html|title=Restoring soil carbon can reverse global warming, desertification and biodiversity|publisher=mongabay.com|access-date=May 5, 2013|date=February 21, 2008|url-status=dead|archive-url=https://archive.today/20130625040133/http://news.mongabay.com/2008/0221-soil_carbon_lovell_interview.html|archive-date=June 25, 2013}}{{cite news|url=http://www.time.com/time/magazine/article/0,9171,1953692,00.html|archive-url=https://web.archive.org/web/20100117215802/http://www.time.com/time/magazine/article/0,9171,1953692,00.html|url-status=dead|archive-date=January 17, 2010|title=How eating grass-fed beef could help fight climate change|publisher=Time|access-date=May 11, 2013|date=January 25, 2010|first=Lisa|last=Abend}} 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.

{{Further|Historic desertification}}

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.{{Cite web |title=Desertification |url=https://pubs.usgs.gov/gip/deserts/desertification/ |access-date=2023-09-11 |website=pubs.usgs.gov}}

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.{{cite web |last=Dregne |first=H.E. |title=Desertification of Arid Lands |url=http://www.ciesin.columbia.edu/docs/002-193/002-193.html |url-status=live |archive-url=https://web.archive.org/web/20230428120939/http://www.ciesin.columbia.edu/docs/002-193/002-193.html |archive-date=28 April 2023 |access-date=3 December 2013 |publisher=Columbia University}}

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.{{Cite book |author=Mortimore, Michael |url=https://books.google.com/books?id=Dx89AAAAIAAJ&pg=PA12 |title=Adapting to drought: farmers, famines, and desertification in West Africa |publisher=Cambridge University Press |year=1989 |isbn=978-0-521-32312-3 |page=12 |access-date=2016-05-16 |archive-url=https://web.archive.org/web/20230730160046/https://books.google.com/books?id=Dx89AAAAIAAJ&pg=PA12 |archive-date=2023-07-30 |url-status=live}} The modern study of desertification emerged from the study of the 1980s drought in the Sahel.

• Aridification
• Oasification
• Deforestation and climate change
• Soil retrogression and degradation
• Water scarcity
• World Day to Combat Desertification and Drought

{{Reflist|30em}}

• {{USGS|title=Desertification|url=http://pubs.usgs.gov/gip/deserts/desertification/|accessdate=2021-05-04}}

{{Commons category}}

{{Portal bar|Environment|Ecology|Earth sciences|Biology|Global warming}}

• [https://www.unccd.int Official website of the Secretariat] of the United Nations Convention to Combat Desertification (UNCCD)
• [http://legal.un.org/avl/ha/unccd/unccd.html Procedural history and related documents] on the UNCCD, from the United Nations Audiovisual Library of International Law
• [http://www.fao.org/in-action/action-against-desertification Official website] of Action Against Desertification, a United Nations Food and Agriculture Organization initiative of the African, Caribbean and Pacific Group of States
• [https://www.unenvironment.org/resources/report/global-deserts-outlook Global Deserts Outlook] (2006), thematic assessment report in the Global Environment Outlook (GEO) series of the United Nations Environment Program (UNEP).

{{Deforestation and desertification}}

{{Human impact on the environment}}{{Climate change}}{{Doomsday}}

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Category:Environmental soil science

Category:Paleoclimatology