From 1440 to 1870, the Transatlantic Slave Trade (TAST) produced the largest forced migration in history; more than 11 million enslaved Africans were transported from Africa to the Americas. Throughout its more than 400-year span, economic, political, agricultural, and natural forces modulated the TAST. Natural forces that affected the TAST included droughts, which affected agricultural productivity over Africa.
Historians have suggested that severe droughts increased the raiding of villages that led to the increase in the transport of enslaved Africans to the Americas. To date there has been no quantitatively based study that links El Niño and African droughts with increases in slave exports. With this in mind, the central hypothesis of this study is that El Niño, a phenomenon that affects global weather patterns, had a significant influence on the TAST. To test this hypothesis, a statistical analysis based on a historical El Niño dataset, which is used as a proxy for African droughts, is combined with the slave voyages data set. The analysis shows a statistically significant correlation at a four-year lag between El Niño and an increase in the number of enslaved Africans transported from West Africa to the Americas. A land-vegetation-atmosphere feedback mechanism is presented that provides a physically based linkage between El Niño, drought, and the TAST. The results are discussed in light of present day climate change and its effects on conflict and migrations in the Middle East.
