Research shows Africa’s exposure to dangerous heat is rising rapidly. Until now, estimating how severe this heat would become was challenging. This was because many widely used global climate models struggled to capture the local factors that shape heat in Africa’s diverse climate zones and habitats (humid tropics, dry savannas and rapidly changing agricultural areas).
It is very important to analyse how these different local factors cause dangerous heat because they all play a role in causing it. For example, rapid changes to the way land is used, such as deforestation, alter soil moisture and humidity. Turning forests into crop land therefore becomes a driver of extreme heat.
To better understand how heat is likely to affect African countries, and to avoid relying on any single climate model, we developed a framework built on four pillars:
The global climate model outputs were adjusted so they matched observed heatwave patterns (the frequency, duration, magnitude, amplitude, number and timing of heatwaves) and showed the links between temperature, wind, radiation and humidity.
Artificial intelligence (AI) was used to quantify how much the different drivers of heat (such as temperature, humidity, soil moisture, wind, radiation, land use) contributed to heatwave changes. We also used AI to highlight how these drivers made heat worse when they interacted.
Some areas, such as the western side of southern Africa, will experience heatwaves that are 12 times as long and frequent as they are now, even if global emissions are reduced. Many heatwaves will last longer than 40 days at a time.
This is not just a slight warming; it is a fundamental change in how people will have to survive on the continent. Once regions in Africa enter a state of almost continuous heatwaves, the human body will have no window of time to recover.
Africa’s heat risk comes from global emissions and local land choices. This means that cutting greenhouse gases matters, and so does protecting and restoring the land’s natural ways of cooling the planet down.
In places with intact forests that cool the air, heat and humidity usually remain below a deadly limit. Forests act like natural air-conditioners, preventing fatal heat.
But when forests are cut down and replaced with cropland, the local climate changes. Crops release large amounts of moisture into the air, raising humidity. Heat and moisture build, and the surface heats up faster during the day and stays warmer at night. The land becomes a heat trap. A hot spell that would have been tolerable under forest cover becomes a prolonged, hazardous heatwave.
Rising background heat can affect entire regions. Rural communities, including smallholder farmers, are also highly exposed because they work outdoors and often have limited access to cooling, healthcare or heat-resilient infrastructure.
Heatwaves will affect shack or informal settlement areas more because they generally lack trees and vegetation, and homes built from metal are harder to cool. Without shade, heat will build and linger.
A Guest Editorial