These all directly affect coastal communities through flooding, erosion and habitat loss. Even a small rise in the baseline sea level means that normal tidal cycles and storm surges reach further inland. This can turn high tides into damaging flood events.
Many people assume ocean levels are uniform, like water sitting flat in a bathtub. In reality, the ocean surface is surprisingly uneven. Winds push water in certain directions. Ocean currents redistribute heat. Temperature differences cause water to expand or contract. Even variations in Earth’s gravity field create bumps and dips in the sea surface. All these factors combine so that sea level can vary by tens of centimetres from one region to another.
African sea levels are rising by approximately 3.54 millimetres each year, which exceeds the global average of 3.45 mm/yr. Perhaps more troubling is that the pace of rise is speeding up, especially in African waters. This acceleration is a long-term trend driven by ongoing ocean warming and ice sheet melting, and it persists regardless of whether any individual year features an El Niño or a La Niña. The ocean continues to absorb heat and receive meltwater from ice sheets year after year, and it is this relentless accumulation, not any single climate cycle, that drives the long-term acceleration.
Africa’s 38 coastal nations are home to over 200 million people living near the shore. Rising seas threaten these communities with flooding, coastal erosion, and saltwater contamination of drinking water and farmland. Rising and warming seas also disrupt fisheries that millions of Africans depend upon for food and livelihoods.
The most dramatic changes are occurring in specific regions. The ocean does not respond to warming and climate variability uniformly. Local factors, including the strength and direction of ocean currents, the depth of warm surface layers, the influence of nearby climate patterns like the Indian Ocean Dipole, and the shape of the coastline and seafloor, all combine to make certain areas far more sensitive to change than others.
The Western Indian Ocean, including waters around Mozambique, Madagascar and the Comoros Islands, shows the highest acceleration of sea level rise at 0.16 mm/yr² with a trend of 3.88 mm/yr.
The Eastern Central Atlantic, encompassing the Gulf of Guinea and waters off west African nations like Senegal, Ghana, Nigeria and Cameroon, follows closely at 3.90 mm/yr. These regions are experiencing both the fastest rise and the sharpest acceleration, making them priority areas for monitoring and adaptation.
The West Africa Coastal Areas Management Program, a World Bank supported regional effort, is a promising model. It aims to help countries manage erosion, flooding and pollution through investments in infrastructure, nature based solutions, and policy coordination.
Protecting Africa’s coasts requires combining oceanographic science with community level planning to build resilience against an uncertain ocean future.
A Guest Editorial