Heavy rainfall between 20 and 22 June struck the coastal regions of the Gulf of Guinea, triggering widespread flooding in Côte d’Ivoire, Ghana, Togo and Nigeria. At several monitoring stations, more than 140 millimetres of rain fell within a few hours. An analysis by World Weather (WWA) attributes the event to ongoing and shows that warming and urban pressures substantially increase flood risk.
Increased heavy rainfall due to warming
WWA concludes that is increasing the frequency and intensity of very heavy rainfall. Warmer air can hold more water vapour — when sufficient moisture is available, rainfall becomes more intense. Short, very intense downpours are particularly problematic because they can trigger flash floods and quickly overwhelm drainage systems.
Urban amplifiers of damage
Rapid, often unplanned urban growth increases sealed surfaces and reduces infiltration. Undersized or poorly maintained drainage, as well as channels clogged with waste, further worsen the situation. As a result, water accumulates in streets and residential areas — even for rainfall amounts that might have been manageable without these pressures.
High vulnerability of informal settlements
Many affected neighbourhoods are located in low-lying areas, along riverbanks or in flood-prone zones. Informal settlements are especially exposed: buildings are often not flood-resistant and protective is lacking. During heavy rain, failures in electricity, water and sanitation systems hit the most vulnerable households first.
Coastal location as an additional stressor
In estuarine and coastal areas, high sea levels or tidal conditions can delay drainage. When this coincides with heavy rain, water levels rise more rapidly. Combined with sealed surfaces and limited drainage , this leads to locally burdens.
Impacts on infrastructure and health
The floods damaged roads, buildings and public , and many people were forced to leave their homes. Disrupted services, contaminated water and damaged sanitation facilities increase the risk of disease outbreaks and complicate recovery for affected communities.
Measures to reduce risk
The analysis underscores the need for adaptation at local and regional levels:
- Unsealing and infiltration areas: green spaces, retention areas and permeable surfaces reduce surface runoff.
- Improved drainage: higher-capacity sewer networks and regular cleaning and maintenance prevent blockages.
- Spatial planning and risk zoning: no new construction in flood-prone areas and gradual relocation of highly exposed settlements.
- Early warning systems and evacuation plans: clear information and rehearsed procedures save lives.
- Nature-based solutions: wetland and mangrove restoration strengthens natural buffers.
Alongside structural and planning measures, reducing global greenhouse gas emissions remains central to limiting future rainfall. Reliable financing mechanisms are also crucial for implementing measures, particularly in countries with limited resources.
Governance and implementation
The combination of climate factors and urban pressures requires integrated responses. Scientific climate impact analyses such as WWA’s help prioritise risks. Effective protection demands political will, long-term planning and the involvement of affected communities so that measures are socially equitable and target the most vulnerable.
Source
World – Climate Change and urban pressures intensify flood risk on the Gulf of Guinea coast