The global average sea level is expected to rise by up to half a metre by 2050 and up to two metres by 2100. This is due to the expansion of seawater from increasing temperatures caused by global warming and melting glaciers and ice sheets, which cover 10% of the Earth’s surface.

Many of Africa’s largest and most densely populated cities, including Lagos, Abidjan and Accra, are located along its low-lying West Coast. They are vulnerable to climate change impacts such as coastal flooding and pollution, which cost the continent around US$4-billion in annual economic losses. These rapidly expanding littoral metropolises are threatened by land mass erosion, coastal flooding and storm surges caused by rising sea levels.

West Africa

These cities contribute significantly to the region’s economy, generating 56% of its gross domestic product, according to a 2020 World Bank report. They also offer vast wetlands, marine resources, opportunities for tourism, and oil and gas reserves.

The prospects for sustainable development along West Africa’s coast are complicated. The population trajectory is forecasted to exceed anywhere else in Africa. It will be accompanied by rapid coastal urbanisation, heightened demand for water and land, and destructive activities like sand extraction – all as sea levels rise.

The Intergovernmental Panel on Climate Change’s (IPCC) Sixth Assessment Report suggests that by 2030, around 116-million Africans could live in densely populated, low-lying coastal areas. The IPCC warns that while coordinated action is needed to address rising sea levels, not enough tangible adaptation measures have been implemented.

The Africa Climate Mobility Initiative converts sea level projections into estimates of potential population exposure to guide policy interventions. These projections must be mainstreamed into various levels of policymaking to be implemented. If adaptation measures aren’t implemented, Africa could face annual damages costs of up to US$10-billion from flooding alone by 2100.

West Africa’s coastline averages about 300 metres above the sea along the Atlantic Ocean, with few mountains, putting these countries at risk. In Ghana, rising sea levels threaten coastal communities in low-lying areas such as Accra, Keta and Takoradi. Senegal’s coastal communities, such as Saint-Louis, Dakar and Ziguinchor, are also vulnerable.

Once sea levels rise, these communities could be displaced by inundation and erosion, losing homes, infrastructure and agricultural land. This exacerbates socio-economic inequalities and public health crises emanating from damage to drainage systems. Implementing long-term solutions, including improved urban planning, resilient infrastructure and planned relocation where adaptation isn’t possible, is crucial to ensure the safety of affected areas.

The impact of rising sea levels is both an environmental and an economic problem. Coastal infrastructure such as ports is critical for the region’s economy, as it supports tourism, fisheries and trade. The World Bank estimates that Côte d’Ivoire lost up to US$2-billion – nearly 5% of the country’s gross domestic product – in damages from rising sea levels in 2019 alone.

Changing coastal ecosystems due to rising sea levels also adversely affect fish populations, diminishing catch potential, compromising food security and jeopardising coastal communities’ socio-economic stability.

These impacts will probably worsen in the coming decades, and adaptation strategies must be urgently implemented to help communities cope. Almost all African countries now have adaptation plans, but these need to be executed coherently and include multiple sectors and levels of government. Sustainable green infrastructure should be developed, including seawalls and mangrove restoration, to protect coastal communities from the effects of rising sea levels.

Protecting and restoring coastal ecosystems can help. Innovative practices like the Green Ghana project can be scaled up to revive degraded mangrove forests, which act as natural barriers against coastal erosion and storm surges.

Early warning systems and community engagement can also reduce vulnerability. This may involve training local communities to respond to emergencies and equipping them with tools and knowledge to protect themselves and their properties.

The challenges must be addressed collectively. Regional efforts to reverse the degradation of ecosystems in the region are already underway in its inland waterways. One example is the Reversing Ecosystem and Water Degradation in the Volta (REWarD-Volta) River Basin initiative. This aims to manage, develop and conserve the natural resources of the basin in six countries – Benin, Burkina Faso, Côte d’Ivoire, Ghana, Mali and Togo – based on transboundary analysis data.

In line with the African Union’s Climate Change Strategy, the Economic Community of West African States has launched the ECOWAS 2050 climate strategy and an initial 2022-2030 action plan to combat climate change and its effects. Implementation will require strengthening the capacity of responsible agencies, mobilising resources for climate finance, adaptation, loss and damage, and regular monitoring and evaluation.

The effects of climate change and sea level rise must feature in ongoing negotiations on international ocean governance. African countries must support the implementation of the treaty to protect marine biodiversity in areas beyond national jurisdiction adopted by the United Nations on 19 June.

Implementing this treaty is crucial to maintain healthy marine ecosystems that are vital in regulating the global climate and could help mitigate the impacts of rising sea levels. These include coral reefs, which act as natural barriers against storm surges.

Embracing the necessary changes and investing in resilient and adaptive measures backed by country and coastal data will help Africa adapt to the impact of rising sea levels.

Written by Ilhan Dahir, Senior Researcher, Climate Risk and Human Security and David Willima, Research Officer, Maritime, ISS Pretoria