Editing Desertification (section)

===Sahel===
{{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&nbsp;mm per year).<ref>{{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}}</ref> So, droughts are the rule in the Sahel region.<ref>{{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}}</ref> The Sahel has lost approximately 650,000&nbsp;km<sup>2</sup> of its productive agricultural land over the past 50 years;<ref>[https://www.thegeographeronline.net/uploads/2/6/6/2/26629356/a116_sahel.pdf Environmental issues in the Sahel] Geo Factsheet</ref> the propagation of desertification in this area is considerable.<ref>{{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}}</ref><ref>{{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}}</ref>
[[File:Village Telly in Mali.jpg|thumb|[[Sahel]] region of Mali]]
The climate of the Sahara has undergone enormous variations over the last few hundred thousand years,<ref name="Lakes">{{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}}</ref> oscillating between wet (grassland) and dry (desert) every 20,000 years<ref>{{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}}</ref> (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°).<ref name="ReferenceA">{{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}}</ref> Some statistics have shown that, since 1900, the Sahara has expanded by 250&nbsp;km to the south over a stretch of land from west to east 6,000&nbsp;km long.<ref>{{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.}}</ref>

[[Lake Chad]], located in the Sahel region, has undergone desiccation due to water withdrawal for irrigation and decrease in rainfall.<ref>{{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}}</ref> The lake has shrunk by over 90% since 1987, displacing millions of inhabitants.<ref>{{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}}</ref> Recent efforts have managed to make some progress toward its restoration, but it is still considered to be at risk of disappearing entirely.<ref name="Remote sensing appraisal of Lake Ch">{{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}}</ref>

To limit desertification, the [[Great Green Wall (Africa)]] initiative was started in 2007 involving the planting of vegetation along a stretch of 7,775&nbsp;km, 15&nbsp;km wide, involving 22 countries to 2030.<ref>{{Cite web |title=Great Green Wall Initiative |url=https://www.unccd.int/our-work/ggwi |access-date=2023-09-22 |website=UNCCD |language=en}}</ref> 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.<ref>{{cite web |title=The Great Green Wall &#124; 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}}</ref>