THE BENGUELA CURRENT is located in the southern part of the Atlantic Ocean and moves northward from the western coast of South Africa, Namibia, and
Angola, merging into the Southern Equatorial Current. It takes its name from the Angolan port of Benguela, which was founded by the Portuguese in 1617. The current was quickly noticed by European seafarers, who initially had trouble navigating the region.
While the Benguela Current is cold, generated by water from the very deepest parts of the ocean moving in line with the rotation of the Earth, the Southern Equatorial Current is warm. The effect of the two merging is the subject of much research, starting with the English geographer James Rennell (1742-1830), whose book Currents of the Atlantic Ocean was published posthumously in 1832. From work by subsequent geographers, it has been found that the Benguela Current also includes subtropical water from the Indian Ocean. About 124-186 mi. (200-300 km.) wide in coastal regions, it becomes much wider as it reaches the tropics, and the cold current is responsible for some of the trade winds in the South Atlantic because there is a certain level of displacement of some of the waters on the surface of the ocean.
The problem facing the Benguela Current from global warming and climate change comes from a rise in the temperature of the water in the oceans, which has led to a rise in the temperature of the waters of the Benguela Current. A Benguela El Niño effect has already been detected. Not only has there been a rise in water temperature as far south as 25 degrees S, but the water has also become increasingly saline. This change may be generated by anomalous atmospheric conditions that have been seen in the western part of the tropical Atlantic Ocean.
Although each year some warm water from Angola has impacted the northern part of the Benguela Current, El Niño has caused this to happen further south. Although this may have occurred throughout history, there are accurate records of it taking place in 1934, in 1963, and in 1984. In 1963 the resultant temperatures off the Namibian coast were some 2-4 degrees higher than normal. The water pressure was also higher. Research by L.V. Shannon suggests that the problem is less frequent, and also has a lower intensity than the similar phenomenon in the Pacific Ocean.
The result of these changes from the Benguela El Niño is expected to have a serious effect on some of the lands in southern Africa, with a dramatic effect on marine life, on the southwest coast of Africa, and also on the trade winds, which are likely to affect marine life and shipping in the southern Atlantic.
Although the impact of the Benguela El Niño is not, at this moment, noticeable south of the Namib-ian port of Lüderitz, if the trend continues, it would have a major effect in the region off the Cape of Good Hope where the south-flowing Agulhas Current meets the Benguela Current. Throughout history, this has resulted in turbulence and storms on the surface of the sea off the southwest coast of South Africa, and the creation of a very rich marine ecosystem underwater. Off the coast of southwestern Africa, there has already been a fall in the catch of the fishing industry, including jack mackerel, sardines, and, off the coast of Angola, anchovies. Whether this is a result of over-fishing in the last two centuries or of less fish spawning because of the rising temperature has not been firmly established, although both are likely to be major contributory causes.
Although the marine ecosystem is likely to be affected, the most noticeable early impact of the Benguela El Niño will be changes in the trade winds. Although these changes will have a dramatic effect on journeys by yachts, it will have a much less important effect on container ships and tankers using the route than would have been the case during the 20th century. However, there will be an impact on the southern coast of Angola and much of the coastline of Namibia.
Over centuries, the current has led to the desertification of the coastline of southern Angola and Namibia, making the coastline extremely inhospitable. Some of the bushmen call it "The Land God Made in Anger." Because of the whaling industry, and the many shipwrecks there, it became known in Europe and North America as the Skeleton Coast. Although there is little flora or fauna along the coast, a number of plant and insect species have managed to adapt, making use of the dense sea fogs. Some desert birds also manage to survive. The small human populations that lived there many centuries ago seem to have survived heavily on seafood, with middens from the shells of white mussels still evident.
SEE ALSO: Agulhas Current; El Niño and La Niña; Namibia; Oceanic Changes; Southern Ocean; Southern Oscillation.
BIBLIOGRAPHY. D. Boyer, J. Cole, and C. Bartholome, "Southwestern Africa: Northern Benguela Current Region,"
Marine Pollution Bulletin (v.41, 2000); S.L. Garzoli and A.L. Gordon, "Origins and Variability of the Benguela Current," Journal of Geophysical Research (v.101, 1996); Joanna Guory, A.J. Mariano, and E.H. Ryan, "The Benguela Current," www. oceancurrents.rsmas.miami.edu (cited October 2007); L.V. Shannon, "The Benguela Ecosystem: Evolution of the Benguela, Physical Features and Processes," Oceanography and Marine Biology (v.23, 1985); M.D. Skogen, "A Biophysical Model Applied to the Benguela Upwelling System," South African Journal of Marine Science (v.21, 1999).
JUSTIN CORFIELD Geelong Grammar School, Australia
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