The environment and the African slave trade

We've noted before (here and here) that the history of slavery, obviously a topic of legal history, has important environmental dimensions, as well. Now, by way of Imperial & Global Forum, we have news of  Emory University’s very impressive Trans-Atlantic Slave Trade Database. At Not Even Past, Henry Wiencek writes that the site

reminds readers that the process of moving enslaved Africans across the ocean was as much an environmental process as an economic one. The map, Wind and ocean currents of the Atlantic basins [below] reveals how oceanic forces played a role in determining the travel routes for slave ships. Red and blue lines respectively denote winds and currents swirling between Africa and the Americas, facilitating particular geographic courses better suited for crossing the ocean. These natural forces effectively created two separate “slave-trading systems,” as the site identifies them: one originating in Europe and North America and the other originating in Brazil. Historians have certainly detailed the racism and greed motivating the slave trade, but comparatively little time examining the environmental processes that made it possible. Particular centers of trade emerged along the coasts of Brazil, the Caribbean and West Africa to meet an economic need, but also to harness the currents and winds essential to moving so many men and women such vast distances.  And here too, the visual character of the map makes it easy to see how natural forces worked to shape the historical events.