Unbearable Heat – Heat with no end: climate model sets out an unbearable future for parts of Africa

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People often think of a heatwave as a temporary event, a brutal week of sun that eventually breaks with a cool breeze. But as the climate changes globally, in parts of Africa, that level of heat is becoming a permanent part of the weather.

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.

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We are a team of hydroclimate and land-atmosphere scientists who study heat extremes, water resources, the way land use changes, and hydroclimate risk. We set out to produce reliable, locally relevant projections of future heatwaves. Our team realised that to understand the true heatwave risk in Africa, we had to look down as well as up. It is not only the warming atmosphere from above, it is also the way people are transforming the land below.

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:

• To get the most accurate data, we studied 10 global climate models rather than betting on one model.

• 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.

• We compared what would happen in a high-pollution future as opposed to one where governments and industry managed to reduce carbon emissions.

Our research found that by the late 21st century, most regions in Africa will stop having occasional heatwaves and will suffer from extreme heat lasting most of the year. The study shows that by 2065-2100, many parts of Africa (apart from Madagascar) could experience heatwaves on 250-300 days per year.