Climate change is intensifying extreme heat episodes across the globe, with tropical regions experiencing the most severe impacts.
Research shows that extreme heat events that once occurred once every decade in the tropics could happen twice a week under certain climate scenarios (Paçal et al., 2023).
West Africa, including Ghana, is urbanising rapidly, and by 2030 more than half of the region’s population is projected to live in cities (CDD, 2018).
As urban areas expand, understanding the physical drivers and consequences of urban heat becomes increasingly important for developing effective monitoring and mitigation strategies.
Urban heat refers to the phenomenon where cities experience significantly higher temperatures than nearby rural areas, largely due to human activities and changes to the natural landscape.
This well-known effect, the Urban Heat Island (UHI), is becoming more pronounced as urbanisation accelerates.
The impacts of UHI are far-reaching.
Health risks increase as prolonged exposure to high temperatures leads to heat-related illnesses such as heat strokes and cardiovascular complications (Li & Bou-Zeid, 2013).
Energy consumption rises as households and businesses rely more heavily on air conditioning, driving up electricity demand and carbon emissions (Santamouris et al., 2017).
Air quality worsens because elevated temperatures accelerate the formation of ground-level ozone and smog, exacerbating respiratory problems (Stone, 2005).
Water resources become stressed as heat increases evaporation and raises the demand for cooling water (Pataki et al., 2011).
Local ecosystems also suffer; rising temperatures disrupt biodiversity and alter habitats for plant and animal species (Grimm et al., 2008).
Nighttime temperatures play a particularly important role in heat-related risk.
Heat exposure accumulates over time, and when nights fail to cool sufficiently, the human body cannot recover from daytime heat stress (Basu & Samet, 2002). Studies show that high minimum temperatures are more strongly associated with mortality than daytime peaks (Kuras et al., 2017).
This is also a social equity issue: people without air conditioning or those living in poorly ventilated housing are disproportionately exposed to dangerous indoor temperatures during the night.
The UHI effect is also most intense after sunset, making nighttime heat a critical concern for urban populations.
Drivers
Several physical factors drive urban heat.
Concrete, asphalt, and other impervious surfaces dominate modern urban landscapes, altering the natural energy balance.
Cities often lack vegetation, reducing the shading and cooling benefits of trees and green spaces.
Human activities such as transportation, industrial operations, and the widespread use of air conditioners release waste heat that raises local temperatures.
Dark urban surfaces like asphalt roads absorb large amounts of solar radiation due to their low reflectivity.
Air pollution also contributes to warming, as certain pollutants trap heat in the atmosphere.
Dense clusters of buildings, especially high-rise structures, can obstruct airflow and trap heat within narrow streets.
As Ghana’s cities continue to grow, addressing the UHI effect will be essential for improving public health, enhancing livability, and building climate-resilient urban environments.
Several practical solutions exist.
Expanding green spaces, planting trees, and encouraging the use of green roofs can provide natural cooling through shade and evapotranspiration.
Using cool or reflective roofing materials reduces heat absorption in buildings.
Permeable pavements help lower surface temperatures while improving water infiltration.
Smarter urban planning—such as designing wider streets, improving airflow, and integrating green corridors—creates cooler, healthier neighbourhoods.
Reducing waste heat through energy-efficient buildings, improved public transport, and sustainable cooling technologies can further mitigate urban heat.
Understanding and addressing urban heat in Ghana is not just an environmental issue; it is a public health, economic, and social priority.
Thoughtful planning today will ensure that Ghanaian cities remain resilient and liveable in a warming world.
The writer is associate Professor and dean, school of graduate studies, Cape Coast technical university.
