How cities are adapting to a warming world

Cities are especially vulnerable to extreme heat — and increasingly experience days when the sidewalks seem to cook like a stove and it's a struggle to sleep at night.

Densely built urban areas, with their paved roads, impermeable surfaces and limited green spaces, are heat islands that can be 10 to 15 degrees Celsius (up to 30 degrees Fahrenheit) hotter than surrounding rural areas. That extra heat strains crucial city infrastructure and harms public health. Nearly half a million people die every year from heat-related causes, according to UN figures.

Climate change caused by our fossil fuel emissions will mean more frequent, more intense and earlier heat extremes in coming years. But cities — home to more than half the world's population — are working to stay livable, sharing adaptation and resilience strategies that will be discussed at preparatory UN climate talks in Bonn this week and next.

"Heat is a silent killer, but it is not an inevitable one," saidHans Henri P. Kluge, the World Health Organization's regional director for Europe, presenting updated guidance on heat protection measures on Thursday. "We have the tools. Now we must use them."

'Nature of heat has changed'

"Today, heat is no longer simply a local climatic characteristic. It has become an urban, public health, economic and socio-environmental challenge," said Leonardo Madeira Martins, a sustainability leader for the city of Teresina, in northeastern Brazil.

Although the dense tropical city is known for its green spaces, Martins said the temperature now frequently exceeds 40 C (104 F). That, he wrote in an email, disrupts "urban mobility, sleep quality, productivity and the overall well-being" of the city's population of around 870,000.

Residents of Antalya, Turkey — host of the upcoming COP31 UN climate talks — have also noticed a change in the summer weather.

"Antalya is a Mediterranean city where summers have always been hot; however, the nature of the heat has changed," said Melike Kireccibasi, a climate expert with the municipality. She told DW that heat waves are beginning earlier, lasting longer and becoming more frequent — a trend that is could "intensify significantly toward mid-century," especially in the densely populated urban center.

"This places increasing pressure on our population — now exceeding 2.6 million — as well as on our health services, our energy and water systems, and the millions of visitors we host every summer," she added.

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Especially at risk: Children, older and sick people

Homes, workplaces and other buildings can shield people during these periods of intense heat, but even they can only do so much. If extreme temperatures persist into the night, people living in overheated buildings struggle to cool off — and that's especially dangerous for vulnerable groups like children, older and sick people.

Antalya wants to adapt buildings and help residents live with the heat, said Kireccibasi. That includes air conditioning systems, but also reducing "how much cooling our buildings need in the first place." An EU-supported heat risk assessment of the city, using satellite data and climate projections, has pinpointed residents who are most exposed to rising temperatures.

The city's strategy includes better building design that increases shade use prioritizes surfaces that reflect heat or insulate, like a green roof. Other solutions include public water points and increased energy efficiency. "In this way, cooling can become more economical, more accessible and lower in carbon intensity," said Kireccibasi.

Structural limitations and social inequality are also making the heat worse in Brazil. "In a middle-income city such as Teresina, not all families have continuous access to air conditioning," said Martins. That has created a public health challenge, "especially in vulnerable communities and peripheral areas, where many homes have poor ventilation, inadequate roofing, and limited urban tree coverage."

An ongoing UN-supported research project has given Teresina insight into how extreme heat affects the health of pregnant women and their babies, especially in disadvantaged communities. Martins said the findings have allowed the city to develop a strategy which includes access to information and resources to help manage heat during pregnancy.

Teresina is working to preserve and expand its urban forests, wetlands and green corridors, which can absorb heat and make it easier for the city to cool itself naturally. Shaded community gardens and shared public spaces are also part of the mix.

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Another Brazilian metropolis, Fortaleza, has launched a network of 10 weather stations that provides real-time data on temperature, UV index and humidity in areas of the coastal city most susceptible to urban heat.

"By making this information transparently available to the public, we aim to foster a shared understanding of the risks associated with extreme heat and encourage the collaborative development of solutions to address them," said Mayor Evandro Leitao in an email.

'Growing a generation' that knows how to live with heat

In its drive to address extreme heat, Fortaleza is targeting public schools with a plan to install air conditioning system-wide by 2028, powered in part by solar energy. The city also wants to bring back green spaces to bare schoolyards.

"We know that high temperatures directly impact students' well-being, concentration and learning process," said Leitao. Schools are also key to the cooling plan in Kilifi County, Kenya, northeast of Mombasa. In a bid to reverse rampant deforestation, government-backed clubs at boarding schools and colleges now teach students how to plant and care for new shade trees.

"When they go back home, they plant trees within their home compounds," said Wilfred Kenga Baya, energy director for the county. "We are growing a generation that has knowledge on environmental conservation and issues of [heat] mitigation."

Baya said people in Kilifi's more remote areas — living with unreliable electricity and fewer resources — are often left without ways to escape the heat. In response, the county has prioritized the installation of decentralized solar power systems, reliable local networks that help to cool critical facilities previously excluded from Kenya's national grid — like health centers, schools and households.

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"The adoption of renewable energy has really increased [over] the last few years," said Baya, pointing to how people across the county of 1.5 million have begun switching to fans and cookers powered by solar energy instead of polluting fossil fuels, which contribute to warming.

"These microgrids ensure that lifeline services remain operational without dependence on vulnerable long-distance power transmission lines."

Edited by: Sarah Steffen

This article was last updated on June 12, 2026 to include a statement by Fortaleza's mayor.