Desertification - Sahel Case Study

The Sahel is a semi-arid zone stretching from the Atlantic Ocean in West Africa to the Red Sea in the East, through northern Senegal, southern Mauritania, the great bend of the Niger River in Mali, Burkina Faso, southern Niger, northeastern Nigeria, south-central Chad, and into Sudan (Brittanica). It is a biogeographical transition between the arid Sahara Desert to the North and the more humid savanna systems on its Southern side. The Sahel has been increasingly impacted by desertification, especially during the second half of the twentieth century. During this period, the Sahara desert area grew by roughly 10%, most of which in the Southward direction into the semi-arid steppes of the Sahel. 

Droughts, grazing, and recharging aquifers

The Sahel’s natural climate cycles make it vulnerable to droughts throughout the year, but during the second half of the twentieth century, the region also experienced significant increases in human population and resulting in increases in the exploitation of the lands through (cattle) grazing, wood- and bush consumption for firewood, and crop growth where possible. These anthropogenic processes accelerated during the 1960s when relatively high rainfall amounts were recorded in the region for short periods of time, and grazing and agricultural expansion were promoted by the governments of the Sahel countries, seeing a good opportunity to use the region’s ecosystem for maximizing economic returns. This resulted in the removal of large parts of the natural vegetation, including shrubs, grasses, and trees, and replacing them with crops and grass types that were suitable for (short term) grazing. Natural aquifers which were previously able to replenish their groundwater stocks during the natural climate cycles were no longer able to do so and the regions closest to the Sahara desert were increasingly desertified. Removing the natural vegetation removed plant roots that bound the soil together, with over-exploitation by grazing eating away much of the grass. Agricultural activity disrupted the natural system, forcing significant parts of the Sahel region to become dry and barren. Before the particularly bad famine of 1984, desertification was solely put down to climatic causes. However, after the mid-1980s, human-caused contributions were identified and taken seriously by the United Nations and many non-governmental organizations.

Severe and long lasting droughts followed throughout the 1960s-1980s, and impacted the human settlements in the forms of famine and starvation, allowing the Sahara desert to continue to expand southward. 

As a result, a barren and waterless landscape has emerged, with the northernmost sections of the Sahel transformed into new sections of the Sahara Desert. Even though the levels of drought have decreased since the 1990s, other significant reductions in rainfall have been recorded in the region, including a severe drought in 2012. It is estimated that over 23 million people in the Sahel region are facing severe food insecurity in 2022, and the European Commission projects that the crisis will worsen further amidst rising social security struggles. As the Sahel dries, the Sahara advances: and it is estimated to advance with a rate of 60 kilometers Sahel lost and Sahara desert gained per year. 

Human influence is an important factor in the Sahel’s desertification, but not all can be attributed to human behavior, says Sumant Nigam, a climate scientist at the University of Maryland. “There is an important anthropogenic influence there, but it is also being met with natural cycles of climate variability that add and subtract in different periods,” Nigam said. “Understanding both is important for both attribution and prediction.”

 

References

https://www.wearewater.org/en/the-sahel-desertification-beyond-drought_318262

https://knowledge.unccd.int/publications/drought-desertification-and-regreening-sahel

https://earth.org/data_visualization/the-past-present-and-future-of-the-sahara-desert/

https://www.nature.com/articles/s41598-020-61085-0

https://e360.yale.edu/digest/the-sahara-desert-has-grown-10-percent-since-1920

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