How Is the World Coping with Extreme Heat?
We asked WRI experts Carter Brandon and Ruth Engel how people, cities and health systems can adapt to extreme heat.
From hydration breaks during the FIFA World Cup to recent heat waves leaving Europe sweltering in an early summer, extreme heat is reshaping daily life.
Around the world, communities are adapting in real time to increasingly high temperatures. During Europe’s heat wave in June, schools closed across the UK, while Paris opened the Canal Saint-Martin for swimming to provide relief from the heat. Elsewhere, street vendors in Mathare, Kenya, have shifted their work to the cooler evenings. And outdoor workers in Hermosillo, Mexico, now start their day before sunrise to avoid the hottest hours.
Cutting climate-harming emissions to prevent further warming is essential. But as temperatures continue to rise, adapting to extreme heat is becoming increasingly urgent. WRI experts Carter Brandon, senior fellow, and Ruth Engel, extreme heat and environmental health data scientist at WRI Ross Center for Sustainable Cities, unpack how people, cities and health systems are responding to rising temperatures, which solutions work and what more is needed to prepare for a hotter future.
Featured Experts:
 | Carter Brandon, Senior Fellow, WRI |
 | Ruth Engel, Environmental Health and Extreme Heat Data Scientist, WRI Ross Center for Sustainable Cities |
What makes extreme heat such a growing public health threat?
Ruth: Extreme heat is already a severe environmental health crisis. In Europe, for example, the world’s fastest-warming continent, heat is estimated to have killed more people in 2025 than road crashes did that year, and a record-breaking heat dome event this year looks set to continue that trend. By 2050, the climate crisis could claim nearly 16 million lives in total, mostly across low- and middle-income countries, including nearly 1.6 million heat wave-related deaths across high-risk areas.
Heat is a regional climate phenomenon that is experienced very personally: your workplace, home and local environment shape how hot you are, and determine how much time you spend in dangerously hot conditions.
As a result, different communities face very different levels of heat exposure, and some face much greater risks than others. People who work outdoors or in factories and warehouses, live in informal settlements and lack access to green space are particularly vulnerable, as are children, older adults and pregnant women.
Some cities have designed adaptations specifically with vulnerable populations in mind. In Freetown, Sierra Leone, for example, the city’s Chief Heat Officer led efforts to install canopies over outdoor market stalls — many run by women — to shield vendors from dangerous heat.
Cities are especially at risk because they are often hotter and warming more quickly than non-urban areas. This creates opportunities to use infrastructure and other interventions to protect people in urban spaces, such as tree planting, reflective roofs and shaded public spaces.
How are people and cities adapting to extreme heat?
Ruth: Many people are already adapting by changing their routines: they commute earlier in the morning, they spend time in air-conditioned public spaces and, where possible, they drive instead of walk.
But people can only adapt so much on their own. A major challenge in addressing heat is shifting adaptation from the personal to the public. The way we plan and build cities shapes how people experience heat — everything from street design to building materials to tree cover can mean that some people feel hotter than others.
Some cities are already being designed to help with cooling. We see this in infrastructure choices, for example, in urban greening in Durban, South Africa, and cool roofs in Atlanta, Georgia. We also see it in social services, such as cooling centers in Barcelona, Spain, and drinking water stations and misting fans in Sydney, Australia. In June, amid a record-breaking heatwave, London launched its first citywide heat plan that outlines goals to adapt across housing, health, transport and green space. The plan emphasizes a need to expand access to cooling spaces and public drinking water, retrofit homes to reduce indoor overheating and increase urban greening. These adaptations are critical to helping people stay safe as they live, work and move through the city.
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How are public health systems adapting to extreme heat, and what more needs to be done?
Carter: Many public health systems are beginning to adapt to more frequent and extreme heat, but most still have a long way to go. The first step is understanding what to expect. Health agencies need to work closely with meteorological and climate agencies to use both short-term weather forecasts and longer-term climate trends.
Short-term forecasts help health agencies warn the public about upcoming heat waves and prepare facilities to treat a surge of patients. Longer-term climate information helps them plan for the future, from determining what health facilities, equipment and staff they’ll need to ensuring clinics can continue operating during extreme heat and power failures driven by spikes in local electricity demand.
Some countries are already doing this. In Argentina, for example, the National Meteorological Service and the Ministry of Health work together to issue heat alerts and public health advice before dangerously high temperatures arrive, giving people and health services time to prepare. Between October 2021 to March 2022, 987 daily alerts were issued. Other cities like London, Madrid and Prague also operate heat wave warning systems that send alerts to residents and health services ahead of extreme heat events. Studies in France and Italy have found that national heat warning systems have helped reduce heat-related deaths by up to 23%.
How is the way we communicate extreme heat risk changing?
Ruth: As heat becomes more common and more intense, we’re seeing a shift from weather-focused language — terms like air temperature and “heat wave” — toward discussions of physiological terms related to heat exposure and its impacts. This is important because it moves us from thinking of heat as an ambient background condition to recognizing it as a hazard in its own right. We’re also seeing more people understand terms like “wet-bulb globe temperature” and concepts like “thermal comfort,” which describe safety and the human experience of heat more accurately.
These changes in language reflect a broader shift toward taking heat seriously and treating it as a significant public health risk. We’ve seen early warning systems and community resources able making a significant difference in protecting people by raising awareness of cooling resources and ways to adapt to extreme heat.
These programs need to be guided by integrated, community-centered heat action plans that use data to help people understand when, how and where to access protections.
How should cities and countries decide where and how to protect people from extreme heat?
Ruth: Heat exposure is complex. Policymakers need to consider not only where it’s hottest, but also who is most vulnerable to heat based on both demographic factors and the places where they spend time on a hot day. Then we need to consider which interventions are best suited to local conditions. Because heat risks are uneven, it’s important to prioritize inclusive, equitable heat action for the people most exposed to heat and at greatest risk.
Different interventions work best in different places. Shade may be the most effective solution to protect people in an outdoor marketplace, while cool roofs may do more to keep homes cooler at night. Cities need robust data to identify where action is needed the most and which solutions will have the greatest impact.
Data-driven resources such as WRI’s Cool Cities Lab can help meet the need for hyper-local and context-specific analyses by providing a comprehensive picture of vulnerability within cities and then modeling how different interventions can provide cooling and reduce heat risks where people live, work and spend time. For example, in Hermosillo, Mexico, neighborhood-level mapped showed that the areas of the city with almost no vegetation can feel up to 14 degrees C (25.2 degrees F) hotter than other regions of the city. Officials are now helping those hotter areas adapt to heat with tree planting initiatives.
Carter: Protecting people from extreme heat requires action at every level, from public health and urban planning to expanding tree cover and cooling public spaces. Our research finds that these investments deliver substantial returns because they save lives while requiring comparatively modest funding. The benefits extend beyond health too, including improved education outcomes, higher worker productivity and even reduced urban violence. Together, these findings make a compelling case for investing in heat adaptation at every scale to help protect people from extreme heat.
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