Sahel drought
The Sahel drought refers to a series of severe drought events that have impacted the Sahel region of Africa, particularly during the late 20th century. This semi-arid area lies between the Sahara Desert and the savanna, spanning 23 countries, primarily in West Africa. Significant droughts occurred in the 1960s, 1970s, and 1980s, leading to widespread famine and the loss of over one million lives due to crop failures. While initially attributed to human activities, research indicates that these droughts correlate more closely with changes in ocean temperatures affecting regional precipitation patterns. Desertification—a process where marginal lands lose vegetation—has been exacerbated by overgrazing and deforestation, contributing to climate challenges in the area.
The Sahel's climate is sensitive to shifts in rainfall and temperature, with ongoing concerns about the impacts of climate change, population growth, and resource competition. Currently, while there are signs of increased rainfall, the future of this trend remains uncertain due to the complex interplay of factors influencing the region's climate. Local communities are actively engaging in sustainable practices, such as planting drought-resistant crops and reforestation, to mitigate these challenges and adapt to changing environmental conditions.
Subject Terms
Sahel drought
Definition
The Sahel (meaning “shore” or “edge” in Arabic) is the region in Africa between the Sahara Desert and the and stretches from the Atlantic Ocean to the Red Sea and Indian Ocean. The area covers all or part of twenty-three countries, the majority of which are in West Africa. Sahel in West Africa is also a geopolitical group made up of nine countries.
The Sahel experienced droughts in 1968, 1973, 1983, 1985, and the late 1980s and 1990s that brought untold hardships to several millions inhabiting the region. The memory of these droughts still commands the world’s attention, as their effects contribute to human suffering and ecological degradation in the region. During this period, more than one million people died of starvation because of crop failures resulting from low rainfall. Goats and other livestock ate everything in sight, including clothes spread outside to dry.
Initially, the droughts of the 1970s and 1980s were blamed on sources, but these do not appear to have been the cause, as the sharp decline in annual precipitation in the Sahel correlates with the difference in temperatures between northern and southern Atlantic Oceans and the Indian Ocean. The slight warming of these oceans may have led to the formation of a deep convective current that is believed to weaken the convergence of the air mass systems that produce precipitation in the Sahel region. The warming of the Indian Ocean is thought to have minimal effect on the Sahel droughts.
On a geologic timescale, the Sahel has experienced wet seasons, as evidenced by buried river valleys seen in radar images of the region and by animal drawings (petroglyphs) on the desert rocks. In addition, geologic records show that the region does experience droughts from time to time. The presence of sand dunes in Lake Chad suggests that the lake was once dry. Multidecadel- to centennial-scale droughts have occurred in the Sahel, and the region’s climate has changed over several millennia as it has experienced desertification.
Significance for Climate Change
Desertification is the process by which marginal lands, such as in semiarid regions, lose natural vegetation cover; it can be anthropogenic or natural. in turn, affects the climate. Desertification is widespread in the Sahel, and it appears to be moving southward.
Few surface waters exist in the Sahel; the Niger River and Lake Chad are the two dominant surface-water bodies in the region. The vast majority of inhabitants are pastoral farmers. Overgrazing occurs in the region, especially during drought. Overgrazing leads to the decimation of vegetation, and this leads to decrease of the land surface albedo—that is, the surface absorbs more incident radiation from the Sun, increasing the temperature at the land surface. This is one of the reasons semiarid and arid regions are hot. In addition, because of the felling of trees for fuel and overgrazing, the land surface becomes exposed to severe wind and water erosion. The wind removes the topsoil as dust, typical of the Sahara Desert to the north. Most African dust comes from the semiarid Sahel region south of the Sahara. As rainfall decreases, more dust is produced. The presence of the dust may reduce daytime temperature by 3° Celsius and increase nighttime temperature by the same amount. Currently, there is an upswing in rainfall.
Drought and conflict are of concern in the Sahel. The increase in population of both humans and animals places a greater demand on resources that may further exacerbate the drought conditions in the region. There is no consensus as to whether the Sahel will experience increased rainfall due to global warming. Although conflicting models make it difficult to predict the outcome of climate change in the area, a higher temperature would lead to higher rates of water evaporation and a greater demand for water.
The pastoral system, land tenure, politics, and climate change would lead to change in land use and land cover (LU/LC). Animals move southward during drought, denuding the land of vegetation. Lack of vegetation would result in severe soil erosion from flash floods and wind erosion, as observed around Lake Chad. The change in LU/LC affects the climate of the region, including the production of dust, and contributes to a positive feedback loop leading to greater desertification and climate change. Although human activities adversely affect the Sahel, the people of the region plant trees and drought-tolerant crops, and they collaborate internationally to minimize adverse effects and to adapt to climate-related changes in the Sahel. However, throughout the 2010s and 2020s, human populations and livestock grazing in the region steadily increased the progress of desertification.
Bibliography
Benjaminsen, Tor A., and Christian Lund, eds. Politics, Properties, and Production in the West African Sahel: Understanding Natural Resources Management. Uppsala, Sweden: Nordic Institute of African Studies, 2001.
Dietz, A. J., Ruben Ruerd, and A. Verhagen, eds. The Impact of Climate Change on Drylands: With a Focus on West Africa. Boston: Kluwer Academic, 2004.
Nicholson, Sharon. “Land Surface Processes and Sahel Climate.” Reviews of Geophysics 38, no. 1 (February 2000): 117-139.
Salgado, Sebastiao. Sahel: The End of the Road. Berkeley: University of California Press, 2004.
Schmidt, Laurie J. "From the Dust Bowl to the Sahel." NASA, 1 Mar. 2021, www.earthdata.nasa.gov/news/feature-articles/from-dust-bowl-sahel. Accessed 21 Dec. 2024.