2023-2024 El Niño amplifies record sea level surges in African marine domains

Africa’s coastal regions face accelerating sea level rise compounded by climate variability. Here we analyze satellite altimetry data from 1993 to 2024 across African marine domains. The 2023–2024 El Niño produced the largest detrended sea level anomaly on record (27 mm), exceeding even the stronger 1997–1998 event. This exceptional response arose from ocean preconditioning: record-positive Indian Ocean Dipole, Atlantic Niño, and Tropical North Atlantic indices preceded and amplified El Niño forcing, while anomalous winds suppressed upwelling and record stratification trapped surface heat, quadrupling ocean heat content. Thermal expansion accounted for over 70% of this event’s total anomaly, reaching nearly 30 mm across the African marine domain. Sea levels rose 11.26 cm since 1993, accelerating at 0.14 mm.yr-2, exceeding the global average. These findings reveal compound threats to low-lying deltas and Small Island Developing States from flooding, ongoing land subsidence, and declining marine productivity. Despite the 2023–2024 El Niño being weaker than 1997–1998, it resulted in the highest detrended sea level anomaly recorded across African coasts, indicating nonlinear ocean response to warming, based on satellite data from 1993 to 2024.