The Sahel region (; , "coast, shore"), or Sahelian acacia savanna, is a biogeographical region in Africa. It is the transition zone between the more humid Sudanian savannas to its south and the drier Sahara to the north. The Sahel has a hot semi-arid climate and stretches across the southernmost latitudes of North Africa between the Atlantic Ocean and the Red Sea. Although geographically located in the tropics, the Sahel does not have a tropical climate.
The Sahel has one of the world's fastest-growing populations due to its high human birthrate, with approximately 80 million people in 2018. The western Sahel in particular has experienced frequent food and water shortages due to droughts caused by its semi-arid climate, as well as high levels of government corruption. Since the 2010s, various coups, insurgencies, terrorist incidents, and foreign interventions have taken place across the Sahel and Françafrique, leading to the region being called the Coup Belt. As a result, the Sahel is viewed as both an ecoregion and a geopolitical space shaped by internal instability and external strategic competition.Clingendael Institute, "The Sahel’s New Geopolitics", June 2024.Vision of Humanity, "Democracy vs. Security: The Sahel's Geopolitical Realignment", 25 September 2024.
Etymology The term is borrowed from the Arabic name for the region, . literally means "coast, shore", which has been explained as a figurative reference to the southern edge of the vast Sahara.
Geography
The Sahel spans from the Atlantic Ocean in the west to the Red Sea in the east, in a belt several hundred to a thousand kilometers (c. 600 miles) wide. It covers an area of .
Representing a climatic and ecological transition zone with hot semi-desert and steppe conditions, the region borders the more humid Sudanian savannas to its south and the dry Sahara desert to the north. This ecoregion is also called the Sahelian acacia savanna in honour of its most prominent and very drought tolerant genus of tree.
The topography is mainly flat; most of the region lies between in elevation. Isolated plateaus and mountain ranges include the Marrah Mountains, Aïr Mountains, and Ennedi Plateau, which are designated as separate ecoregions because their flora and fauna are distinct from the surrounding lowlands (e.g. East Saharan woodlands). Annual rainfall varies from around in the north to around in the south.
Flora and fauna The Sahel is mostly covered in grassland and savanna, with areas of woodland and shrubland. Grass cover is fairly continuous across the region, dominated by annual grass species such as Cenchrus biflorus, Schoenefeldia gracilis and Aristida stipoides. Species of acacia are the dominant trees, with Acacia tortilis as the most common one. In the north, areas of desert shrub, including Panicum turgidum and Aristida sieberiana, alternate with areas of grassland and savanna. During the long dry season, many trees lose their leaves and the predominantly annual grasses die.
The Sahel was formerly home to large populations of grazing mammals, before the larger species were greatly reduced due to over-hunting and competition with livestock. Several species are vulnerable (Dorcas gazelle, cheetah, lion and red-fronted gazelle), endangered (Dama gazelle and African wild dog), or extinct (the Scimitar-horned oryx is probably extinct in the wild, and both Pelorovis and the Bubal hartebeest are extinct).
The seasonal wetlands are important for migratory birds moving within Africa and on the African-Eurasian flyways.
Climate
The Sahel has a hot semi-arid climate (Köppen climate classification BSh). The climate is typically hot, sunny, dry and somewhat windy all year long. The climate is similar to, but less extreme than, the climate of the Sahara desert located just to the north.
The Sahel receives a low to very low amount of precipitation annually. The steppe has a very long, prevailing dry season and a short rainy season. The precipitation is also extremely irregular and varies considerably from season to season. Most of the rain usually falls during four to six months in the middle of the year, while the other months may remain absolutely dry. The interior generally receives between 200 mm and 700 mm of rain yearly.
A system of subdivisions often adopted for the climate based on annual rainfall is as follows: the Saharan-Sahelian climate, with mean annual precipitation between around 100 and 200 mm (such as Khartoum, Sudan); the strict Sahelian climate, with mean annual precipitation between around 200 and 700 mm (such as Niamey, Niger); and the Sahelian-Sudanese climate, with mean annual precipitation between around 700 and 900 mm (such as Ouagadougou, Burkina Faso).
The relative humidity is low to very low, often between 10% and 25% during the dry season and between 25% and 75% during the rainy season. The least humid places have a relative humidity under 35%. Annual rain levels were measured to fall between 20 and 40% in a span of two decades from 1931 to 1960 and 1968–1990; the levels recovered slightly in the mid-1990s in some areas, especially in central and eastern areas as far as Senegal.
The Sahel is characterized by constant, intense heat, with an unvarying temperature. The Sahel rarely experiences cold temperatures. During the hottest period, the average high temperatures are generally between (and even more in the hottest regions), often for more than three months, while the average low temperatures are around . During the cooler period, the average high temperatures are between and the average low temperatures are between . Everywhere in the Sahel, the average mean temperature is over .
The Sahel has very high sunshine duration year-round, approaching desert levels of between 2,400 hours (about 55% of the daylight hours) and 3,600 hours (more than 80% of the daylight hours). The cloud cover is low. Niamey has 3,082 hours of sunshine; Gao has 3,385 hours; Timbuktu 3,409 hours; and N'Djamena 3,205 hours.
Recent droughts
For hundreds of years, the Sahel region has experienced frequent droughts and megadroughts. One megadrought lasted 250 years from 1450 to 1700. There was a major drought in 1914, leading to large-scale famine. From 1951 to 2004, the Sahel experienced some of the most consistent and severe droughts in Africa. The 1960s saw a large increase in rainfall in the region, making the northern drier region more accessible. There was a push, supported by governments, for people to move northwards. When the long drought period from 1968 through 1974 began, grazing quickly became unsustainable and large-scale denuding of the terrain followed. Like the drought in 1914, this led to a large-scale famine, but this time somewhat tempered by international visibility and an outpouring of aid. This catastrophe led to the founding of the International Fund for Agricultural Development.
2010 drought
Between June and August 2010, famine struck the Sahel. Niger's crops failed to mature in the heat, 350,000 faced starvation, and 1,200,000 were at risk of famine. In Chad the temperature reached on 22 June in Faya-Largeau, breaking a record set in 1961. Niger tied its highest temperature record set in 1998, also on 22 June, at 47.1 °C in Bilma. That record was broken the next day, when Bilma hit . The hottest temperature recorded in Sudan was reached on 25 June, at in Dongola, breaking a record set in 1987. Niger reported on 14 July that diarrhoea, starvation, gastroenteritis, malnutrition and respiratory diseases had sickened or killed many children. The military junta appealed for international food aid and took serious steps to call on overseas help. On 26 July, the heat reached near-record levels over Chad and Niger, and in northern Niger about 20 people reportedly died of dehydration by 27 July.
Desertification and soil loss
The Sahel region faces environmental issues that are contributing to global warming. If the change in climate is not slowed down and desertification possibly reversed through sustainable practices and any form of reforestation, it is only a matter of time before countries like Niger lose their entire landmass to desert due to unchecked unsustainable human practices. Over-farming, over-grazing, over-population of marginal lands, and natural soil erosion have caused serious desertification of the region.Schmidt, Laurie J. (18 May 2001). "From the Dust Bowl to the Sahel". NASA. This has affected shelter construction, making it necessary to change the used materials. The Woodless Construction project was introduced in Sahel in 1980 by the Development Workshop, achieving since then a high social impact in the region. A major initiative to combat desertification in the Sahel region via reforestation and other interventions is the Great Green Wall.Major dust storms are a frequent occurrence. During November 2004 several such storms hit Chad, originating in the Bodélé Depression. This is a common area for dust storms, occurring on average on 100 days every year. On 23 March 2010, a major sandstorm hit Mauritania, Senegal, The Gambia, Guinea-Bissau, Guinea, and inland Sierra Leone. Another struck in southern Algeria, inland Mauritania, Mali and northern Ivory Coast at the same time.
Following the drought period of the 1970s and 1980, however, the Sahel began to experience increased rainfall. This may be due to global warming, which can cause stronger monsoons, in turn caused by a warmer Atlantic Ocean. Warming of the Mediterranean Sea may also be a factor. Groundwater levels are also rising, even more than can be accounted for just from the increased rainfall, according to some hydrologists. Other possible contributing factors include the Great Green Wall, the revival of traditional water harvesting methods and the abandonment of irrigation projects.
Protected areas Protected areas include Ferlo Nord Wildlife Reserve in Senegal, Sylvo-Pastoral and Partial Faunal Reserve of the Sahel in Burkina Faso, Ansonga-Ménake Faunal Reserve in Mali, Tadres Reserve in Niger, and Waza National Park in Cameroon.
Culture
Traditionally, most of the people have been semi-nomads, farming and raising livestock in a system of transhumance. The difference between the dry north with higher levels of soil nutrients and the wetter south with more vegetation is exploited by having the herds graze on high-quality feed in the north during the wet season, and trek several hundred kilometers to the south to graze on more abundant but less nutritious feed during the dry period. In the western Sahel, polygamy and child marriage are common. Female genital mutilation is also practiced across the Sahel.
Music Blues historians and historians of African-American music, such as Paul Oliver and Samuel Charters, have suggested that the essential elements of the blues originated in the Sahel, brought over by Africans via the slave trade. The slaves brought to South America and the Caribbean were largely from percussion-based musical cultures in southern, coastal West Africa (like southern Nigeria), as well as Central African and Bantu-speaking parts of Africa, whose musical cultures lacked many elements that would become characteristic of the blues. In contrast, many of the slaves brought to North America were from the Sahel region and much more familiar with stringed instruments; the banjo evolved from Sahelian string instruments such as the akonting. Charters found that many Sahelian slaves were from Muslim cultures, favouring stringed, melodic, and solo melismatic singing, which differed from the drum-based music of other African regions, who generally favoured drumming and group chants. These traditions—which were sometimes permitted by plantation owners who feared drums—became tools of rebellion, evolving into blues.