Underwater: Global Warming to Flood the Former Ports of the Transatlantic Slave Trade

From time to time, a new marker is placed. Since 2011, the Middle Passage Ceremonies and Port Markers Project has laid down markers and organized ceremonies in honor of the approximately two million enslaved Africans who perished at sea during the period of the transatlantic slave trade between the sixteenth and nineteenth centuries. In the United States alone, the project has identified 52 ports that were at one point directly involved in the trade. Presently, the group managed to place markers in 20 ports, and organize ceremonies in 22. Each marker is unique and the ceremonies incorporate rituals from different religions intended to address the painful memory and legacies of the slave trade. The markers in particular have the additional purpose of reminding future generations about the history of the traffic. However, in this current age of global warming, and rising sea levels, one may very well wonder: how long until these ports are fully submerged?

Data from a couple of digital resources available to the public may help us address this question. The Gradient Fingerprint Mapping tool of NASA’s Jet Propulsion Laboratory at the California Institute of Technology allows users to simulate local sea level changes overtime caused by the melting of glaciers and ice sheets for a total of 187 locations around the globe. Not all of these places participated in the transatlantic slave trade, of course, but many of them did or are located near ports that did so in Africa, Europe, and the Americas. Users can measure local sea level changes by millimeters per year. They can also view projections calculated for 10, 50, 100, 200, and 1000-year periods. Changes in sea level vary according to the Earth’s gravitational and rotational potentials. Meanwhile, patterns of inundation depend on the location of the drainage system. Ice melted from western Greenland, for example, affects London more than New York. The simulation tool unfortunately lacks data on the elevation of the listed places, but the Falling Rain gazetteer provides comparable information in feet and meters for almost every location of the world. A simple conversion is all that is necessary to calculate how long it will take for each place available in the tool to be completely underwater.

The idea that temperatures around the world have been increasing as a function of human activity has gained significant traction lately. However, scholars debate the origins of this relationship. Some date it to the arrival of Europeans to the Americas in the late fifteenth century. Others favor a more recent date, coinciding with the Industrial Revolution in Britain. Be that as it may, the impact has been huge, resulting in a new chapter or epoch in the geological record, recently dubbed the “Anthropocene.” The transatlantic slave trade played a central role in that process of global warming. It involved the transportation of some 12.5 million enslaved Africans on ships departed from Europe and the Americas over a period of almost four centuries. It spread contagious diseases that contributed to the near annihilation of indigenous populations in the Americas. It destroyed forests, cleared lands, opened mines, changed the course of rivers, and built entire new cities where previously none existed. It created new financial institutions that underpinned the traffic and fostered industrialization in Europe and North America, where many of the crops enslaved Africans produced were processed for sale and consumption throughout the world, including sugar, rice, tobacco, and cotton. The slave trade thus contributed not only to global inequality, but to increased temperatures worldwide as well.

In any case, the sea will claim ports north and south of the Equator. To some of them the threat of inundation is imminent. Although sitting somewhat up the Mississippi River, New Orleans is already below sea level and prone to floodings caused by tropical storms, another hazard intensified by global warming. Charleston, in South Carolina, is another city that should concern government officials. It was the principal port of slave disembarkation in North America. City planners have sought to build an African American museum there, facing the waterfront with views past Fort Sumter toward the Atlantic Ocean, but everything may flood within a century or so. Cities in northeast Brazil, like Recife and maybe Salvador, were leading ports in the transatlantic slave trade and are also at imminent risk of inundation.

Similarly, some ports in the Mediterranean Sea, like Naples and Venice, financed many of the earliest transatlantic slaving voyages in history, but they will soon meet a similar fate as the Africans who perished at sea. Venice, in particular, has long been struggling to keep itself afloat. In northern Europe, Copenhagen, Helsinki, and possibly Edinburgh participated in the traffic variably, but they are also at risk of inundation. Ports in three African regions can flood in a century or so: Upper Guinea, especially the coast stretching from Guinea to Liberia; the Bight of Biafra in southeast Nigeria; and the East African coast comprehending Tanzania and Mozambique. All of these regions were once deeply engaged in the transatlantic trade, with the latter also involved in the Indian Ocean traffic. Northern Mozambique just had a taste of what is to come, after a cyclone inundated communities miles inland last year.