Cooling Africa's cities: Inside the World Bank's urban heat playbook

Gavin Allen: Your team recently published the Handbook on Urban Heat Management in the Global South. What were the most surprising or urgent findings when you looked specifically at cities in Eastern and Southern Africa?

Abhas K. Jha, Practice Manager, Urban Development, Resilience and Land, Eastern and Southern Africa (AFE)The World Bank

Abhas K. Jha: What stood out most is how quickly heat risk is outpacing the capacity of African cities to respond. Extreme heat is already one of the deadliest and most costly climate risks in cities. By 2050, the number of urban poor exposed to dangerous heat could rise by roughly 700 percent, with the largest increases in Africa and Asia.

In Eastern and Southern Africa, three patterns are especially clear.

First, the combination of climate change and rapid urbanization is creating hotspots several degrees warmer than surrounding areas. In cities like Nairobi, Addis Ababa, and Lusaka, urban zones are already 3–4°C hotter than nearby peri-urban areas because of dense construction, asphalt, and limited tree cover. In some fast-growing cities globally, the heat-island penalty reaches 10°C — and African cities are moving in that direction as they densify without enough green space or ventilation.

Second, heat is deeply unequal. In Johannesburg and Ekurhuleni, poorer areas such as Soweto, Alexandra, and Tembisa experience nighttime temperatures around 3°C higher than the city average, and could see hot nights rise from about 20 a year today to 120 by mid-century. A similar pattern appears in Dar es Salaam and other East African cities where informal settlements — typically built with tin roofs and limited vegetation — reach far higher indoor temperatures and carry much higher health risks.

Third, heat is becoming a development challenge, not just a weather phenomenon. Unmanaged heat erodes labor productivity, pushes people into more precarious livelihoods, strains fragile health systems, and encourages internal migration. This is why we framed the Handbook as a practical playbook for mayors and national governments, not just a technical climate report.

Gavin Allen: Many African cities are growing extraordinarily fast. How does rapid urbanization alter the heat profile of a city, and what unique challenges does this create compared to regions with slower growth?

Abhas K. Jha: Rapid urbanization changes the physical behavior of a city. When wetlands, farms, and tree cover are replaced by concrete, metal roofs, and asphalt, the city absorbs more solar heat during the day and releases it slowly at night. That is the urban heat island effect — and in African cities, it's intensified by the pace and pattern of growth.

African cities have some of the fastest urbanization rates in the world, with annual growth around 3.5 percent. Much of this expansion is informal: housing is crowded, streets are narrow, and little space is reserved for parks, ventilation corridors, or water bodies. Studies show that as built-up area expands across East African cities, heat-island intensity rises both day and night.

What makes Africa's situation unique is that heat risk is rising before cities have adequate infrastructure and institutions. In Europe or North America, heat islands overlay strong transport systems, solid building regulations, and widespread access to mechanical cooling. In many African cities, people live in self-built housing with metal roofs, commute in overcrowded minibuses, and work outdoors without reliable electricity.

This creates three constraints:

• Limited municipal budgets to retrofit existing neighborhoods.
• Low access to sustainable cooling, meaning households simply endure the heat.
• Planning systems that struggle to keep up, so heat risk gets "locked in" parcel by parcel.

This is why integrating heat into land-use planning, transport investments, and housing programs in Africa is a "now or never" opportunity.

Gavin Allen: In many African cities, informal and low-income neighborhoods face the highest heat exposure. Where is this most visible, and what solutions work best in these communities?

Abhas K. Jha: The contrast is stark even across short distances. In South Africa, dense townships with few trees — such as parts of Alexandra or Soweto — can be 3–6°C hotter than leafier suburbs on the same day. By 2050, poorer neighborhoods may endure up to 120 hot nights per year, while wealthier areas face far fewer.

In Dar es Salaam, tin roofs, crowded housing, and limited access to water or electricity expose residents to extreme heat. Studies in South African informal settlements show indoor temperatures 4–5°C higher than outdoors, with homes in heat-stress conditions for roughly a third of hot-season hours.

The most effective solutions tend to be simple, local, and co-designed. Three approaches consistently stand out:

Cool roofs and better materials. Painting metal roofs with reflective coatings and adding low-cost insulation offers dramatic reductions in indoor heat. One multi-country study found cool roofs could cut up to 91 percent of annual heat-stress exposure in tropical informal settlements.

Trees and micro-parks. Targeted tree-planting in hotter, low-income areas delivers far more cooling per unit of canopy than in wealthier districts. Moving toward 30–40% canopy in strategic areas can reduce local temperatures by 0.4°C on average and by several degrees on individual streets.

Community-driven greening and water points. Pocket gardens, green roofs, small shaded spaces, municipal shade structures, safe water points, and early-warning systems together reduce heat stress and improve health — while creating small green-economy livelihoods.

The broader point: heat management in informal settlements is not a luxury. It's part of delivering basic, dignified services.

Gavin Allen: Africa's cities need solutions that work at low cost and can be implemented quickly. Which nature-based strategies deliver the greatest cooling impact per dollar spent?

Abhas K. Jha: The highest-payoff investments are trees, shade along movement corridors, and hybrid "green-gray" solutions that piggyback on existing infrastructure.

Trees are the anchor. Increasing tree coverage to about 30% in cities can reduce average temperatures by around 0.4°C, with local reductions of 5–6°C. A small park in Kochi, India, for example, reduced electricity use and flood risk while saving residents significant health and drainage costs. African cities need precisely these multi-benefit investments.

Shade systems on key public routes — pergolas with vines, shaded walkways to clinics and schools, covered markets — offer major return on investment. Spanish cities have shown vine-covered streets can cut temperatures by up to 8°C. Similar systems are workable and affordable across Africa.

Hybrid green-gray solutions integrate vegetation into existing hard infrastructure: mangroves with sea walls, or vegetated slopes along arterial roads in hilly cities like Kampala. These absorb heat, manage runoff, and protect assets at lower life-cycle cost.

The key is to place nature where people actually live, walk, and work. A tree in a gated compound benefits few; shade along a bus route benefits thousands.

Gavin Allen: Digital tools are becoming more available across African cities — sensors, satellite analytics, AI-enabled planning. How can technology help cities better understand or respond to urban heat?

Abhas K. Jha: Technology cannot replace trees or good planning — but it can make both far more effective.

At the diagnostic stage, satellite data and open mapping allow cities to identify roof types, expansion patterns, and informal settlements in much greater detail than surveys. Researchers are already tracking how heat islands in Kampala evolve as the city expands.

On the ground, low-cost sensors and community science fill critical data gaps. In Tshwane, Cape Town, and Buffalo City, residents mounted simple sensors on cars to generate thousands of temperature readings. These revealed 6°C variations between leafy and treeless areas and now inform municipal heat-action plans. AI and analytics help planners identify vulnerable micro-districts, simulate how tree-planting or cool-roof programs would change temperatures, and optimize outreach during heatwaves. New machine-learning models can predict urban heat at neighborhood scale — the resolution city engineers actually need.

Finally, digital alerting systems save lives. SMS or app-based warnings, combined with clear protocols for health, schools, and employers, have already proven effective in cities like Ahmedabad.

The priority is to link data, decisions, and delivery — not accumulate gadgets.

Gavin Allen: Energy use and waste heat from buildings, networks, data centers, and transport are rising across African metro areas. How can cities prevent today's digital expansion from becoming tomorrow's heat burden?

Abhas K. Jha: The danger is that we expand digital infrastructure but unintentionally worsen overheating and emissions. Fortunately, we know the key steps. Improve building performance. Buildings account for roughly 40% of energy-related carbon emissions globally, with two-thirds coming from operations like heating and cooling. Cooling already consumes nearly 20% of building electricity. If African cities adopt poorly insulated designs or full-glass facades, they will import the worst energy penalties from richer nations.

Build energy-smart digital infrastructure. Data centers and networks use about 2–3% of global electricity today, and consumption could more than double by 2030, driven largely by AI workloads. Africa currently has less than 1% of global data-center capacity but needs roughly 1,000–1,200 MW more by 2030. Cities can require efficiency standards, waste-heat recovery, renewable power, and smart siting — for instance, near industrial parks that can reuse low-grade waste heat. Plan transport and land use together. Car-dependent sprawl increases vehicle waste heat, commute times, and air-conditioning demand. Compact, transit-oriented, and greened city forms reduce both emissions and heat.

African metros can still leapfrog to a cooler digital future — but only if digital expansion is integrated into energy and climate strategies.

Gavin Allen: Looking ahead 10 to 15 years, what gives you confidence that African cities can become more livable, cooler, and more resilient? Where do the biggest opportunities lie for innovation?

Abhas K. Jha: I'm cautiously optimistic for three reasons.

First, African cities are still being built. By 2050, the continent's population will at least double, and urbanization will approach 60%. The streets, neighborhoods, and public spaces that will host hundreds of millions of people are not yet fixed, giving policymakers a rare chance to embed cooling and resilience from the ground up.

Second, awareness is rising. Cities are joining global coalitions on sustainable cooling; more than 180 cities have signed the Global Cooling Pledge or are experimenting with practical heat-mitigation measures. Youth groups and community organizations are leading local greening and citizen-science efforts.

Third, the technology stack is shifting. Satellite data, AI-enabled planning tools, and digital twins can pinpoint hotspots and test solutions virtually. New materials for cool roofs, passive buildings, and low-energy ventilation are becoming more affordable. If combined with pro-poor planning, better governance, and smarter finance, African cities can leapfrog toward cooler, more compact, and more equitable urban forms.

The biggest innovation opportunity is not a single technology but aligning data, design, finance, and community action around a simple idea: staying cool in a hotter world is a basic urban service — like water or transport. If African cities get this right, they won't just protect their own citizens; they'll provide a roadmap for the world.