Benguela Niño

Benguela Niño describes a warm phase of interannual variability in the Angola–Benguela upwelling region off southwestern Africa. This region normally experiences wind-driven upwelling that brings cooler, nutrient-rich water toward the surface. During an event, anomalous warming changes the usual coastal temperature pattern. The term is analogous to El Niño, but Benguela Niño events occur in the South Atlantic and need not coincide with Pacific El Niño.

No single mechanism explains every Benguela Niño. Research has linked events to changes in equatorial Atlantic winds that can generate ocean waves travelling toward the African coast, as well as local changes in coastal winds, upwelling, currents and air–sea heat exchange. The 2019 event involved a combination of local and remote forcing. Research on 1995 also found that unusually high Congo River discharge helped amplify that event: lower-salinity water spread southward, limiting vertical mixing with colder subsurface water. This freshwater pathway is a proposed contributor to 1995, not a universal explanation for all events.

Anomalous warming can alter upper-ocean mixing and the upward supply of nutrients, affecting biological productivity, marine ecosystems and fisheries. Benguela Niño events may also accompany increased rainfall in Angola and Namibia and over the arid Namib region. Impacts vary with an event’s strength, duration and physical drivers.

Intense, persistent events were observed in 1984 and 1995. A 2003 study examined the mechanisms behind these warm events and described poleward movement of warm water across the Angola–Benguela front in 1995. During October 2019–January 2020, sea-surface temperatures off Angola and Namibia were more than 2 °C above normal in places, with the event peaking in November 2019. The differing accounts of 1995 and 2019 illustrate that the relative roles of remote and local processes can vary.