Because the Sahel's rainfall is heavily concentrated in a very small period of the year, the region has been prone to dislocation when droughts have occurred ever since agriculture developed around 5,000 years ago. The Sahel is marked by rainfalls of less than a year, almost all of which occurs in one continuous season, which can run from several weeks to four months. Despite this vulnerability, the history of drought and famine in the Sahel do not perfectly correlate. While modern scientific climate and rainfall studies have been able to identify trends and even specific periods of drought in the region, oral and written records over the last millennium do not record famine in all places at all times of drought. One 1997 study, in attempting to map long scale rainfall records to historical accounts of famine in Northern Nigeria, concluded that “the most disruptive historical famines occurred when the cumulative deficit of rainfall fell below 1.3 times the standard deviation of long-term mean annual rainfall for a particular place.” The 1982 to 1984 period, for instance, was particularly destructive to the pastoral
Fula people of Senegal, Mali and Niger, and the
Tuareg of northern Mali and Niger. The populations had not only suffered in the 1968 to 1974 period, but the inability of many to rebuild herds destroyed a decade earlier, along with factors as various as the shift of political power to settled populations with independence in the 1960s, Senegalese-Mauritanian border relations, and Niger's dependence upon falling world uranium prices coinciding in a destructive famine.
600–700 AD Surviving contemporary records of climate in the Sahel begin with early
Muslim travellers in the early
Medieval Warm Period. These suggest that Sahel rainfall was relatively low in the 7th and 8th centuries and then increased substantially from about 800 AD. There was a decline in rainfall from about 1300 AD, but an increase again around 200 years later.
"Little Ice Age" droughts According to a study of West African drought based on Ghanaian lake sediments (not eyewitness historical accounts) published in the journal
Science in April 2009: The most recent of these [multicentury droughts] occurred between 1400 and 1750 CE (550 to 200 yr B.P.), similar in timing to the Little Ice Age (LIA, 1400 to 1850 CE), a well-known interval when Northern Hemisphere temperatures were cooler than at present. In contrast with earlier studies, which reconstructed wetter conditions in East Africa during this period, evidence from
Lake Bosumtwi supports more recent studies suggesting that this interval was dry. Evidence for LIA drought is not restricted to Africa, however. Records from throughout the tropics, including the western Pacific warm pool, the Arabian Sea, continental Asia, and tropical South America all show evidence for dry conditions during this time period. a major drought after generally wet conditions also took place during the 1680s.
1740s and 1750s Cycles of several wet decades followed by a drought were to be repeated during the 18th century. Sahelian drought again killed hundreds of thousands of people in the 1740s and 1750s. The 1740s and 1750s was recorded in chronicles of what is today Northern Nigeria, Niger and Mali as the "Great Famine", the worst for at least 200 years prior. It caused massive dislocation of the Sahelian states of the time, but also disrupted the
Trans Saharan trade routes to North Africa and Europe.
1830s Around 1790 dry conditions similar to those of the late 20th century set in
Early 20th century droughts The first rain gauges in the Sahel date from 1898 and they reveal that a major drought in the 1910s, accompanied by large-scale famine, was followed by wet conditions during the 1920s and 1930s, reaching a peak with the very wet year of 1936. The 1940s saw several minor droughts — notably in 1949 — but the 1950s were consistently wet, and expansion of agriculture to feed growing populations characterised this decade. Many have thought this contributed to the severity of the subsequent Sahel droughts.
Late 20th century droughts Burkina Faso, northern
Nigeria, southern
Niger, far northern
Cameroon (near
Lake Chad) and central
Chad all struggled with dwindling rain fall from the 1960s. The 1968-73 drought severely affected several West African countries. Grazing became impossible and this triggered a large-scale famine that led to the first mobilization of external aid and the creation of the
International Fund for Agricultural Development by
United Nations. Up to 100,000 people and a third of livestock died. This drought was so catastrophic that it became known as the "
Great Sahelian drought". In 1983-84 Sahelian countries received some of the lowest rainfall ever recorded. However, even though this drought was more severe than that of the early 1970s, the human impact was less severe, since economies and societies had developed better coping mechanisms. A literature review from the
African Journal of Ecology summarized the environmental changes that species faced after the late 20th century droughts, some of which includes (but is not limited to) severe declines in biodiversity and increases in other disturbances, such as fires.
21st Century Droughts 2010 Sahel drought Throughout June to August 2010, famine struck the Sahel. Niger's crops failed to mature in the heat which resulted in
famine. 350,000 faced starvation and 1,200,000 were at risk of
famine. In Chad, the temperature reached on June 22 in
Faya-Largeau, breaking a record set in 1961 at the same location. Niger tied its highest temperature record set in 1998, on also June 22, at in
Bilma. That record was broken the next day, on June 23 when
Bilma hit . The hottest temperature recorded in Sudan was reached on June 25, at in
Dongola, breaking a record set in 1987. Niger reported
diarrhoea, starvation,
gastroenteritis,
malnutrition and
respiratory diseases killed and sickened many children July 14. The new
military junta appealed for international food aid and has taken serious steps to calling overseas help since coming to office in February 2010. On July 26 the heat reached near-record levels over
Chad and
Niger.
2012 Sahel drought By the middle of 2010, another drought in the western Sahel was predicted by several organisations for 2011 and 2012. ==Potential contributing factors==