On 28 June, Montse Aguilar swept the streets of Barcelona for seven hours in the sun, at temperatures above 35C. That night, while preparing dinner, the cleaner told a friend that she had had cramps and chest pains. Twenty minutes later, she collapsed in her chair and died.
Her death triggered outrage in Spain, but such tragedies will become more common as the planet warms.
This is a CATCH story
This story is part of Dialogue Earth’s work on the Community Adaptations to City Heat (CATCH) project, in partnership with Boston University. The project is funded by Wellcome. All Dialogue Earth content is editorially independent.
Scientific evidence on the health impacts of heat and its link to climate change is increasingly compelling. In Europe and Latin America, heat already causes thousands of deaths every summer, many of them attributable to the heat that is additionally brought by the climate crisis. In a region as unequal as Latin America, lack of access to drinking water and primary care exacerbates the risks.
The impact of heat is particularly felt in large cities, as their building density and lack of greenery forms “urban heat islands” where temperatures are higher than surrounding areas.
In response, more and more cities are implementing climate shelter networks: spaces that provide cooling to any resident who needs to shelter from the heat. These can be open shaded spaces, such as parks, reserves and squares, or closed spaces, such as museums, schools and community centres.
“Having these kinds of spaces is absolutely necessary because we are experiencing increasingly intense and frequent heatwaves,” says Pilar Bueno Rubial, undersecretary for climate change in the city of Rosario, Argentina.
Some of the climate networks that have sprung up around the world have been a great success, while others have struggled to attract users.
A Greenpeace report that analysed shelters in 16 Spanish cities found shortcomings included limited opening hours, insufficient rest areas, and the fact that not all shelters are free to access. Other obstacles include difficulty of monitoring the effectiveness and cost-benefit of initiatives, as well as properly communicating the existence of the shelters.
Learning what works and what does not is an increasingly urgent task for heat researchers and city planners.
What are climate shelters?
A climate shelter is a space where people can take refuge from extreme heat.
Networks of such shelters have been implemented in many places where heat threatens human health. Some cities have defined such shelters broadly, including parks, specially cooled bus stops and existing public buildings. Others use the term more narrowly for facilities specifically designed and opened to provide people with shelter from heat.
More shelters of all types are likely to be needed as the planet warms.
Barcelona: from cooling centres to climate refuges
Barcelona was the first city to create a formal network of climate refuges in 2019.
Ana Terra Amorim-Maia, a researcher at the Basque Centre for Climate Change, notes that the idea of opening spaces for people to go to in extreme heat already existed in cities in countries such as the United States and Canada, where they are known as cooling centres.
“Barcelona learned from the concept of cooling centres, which were more aimed at vulnerable populations, and expanded access to anyone who needed shelter from the heat, calling them climate shelters,” she says. Today, there are 409 such shelters in the city, which people are directed to if they need to cool off. These include libraries, markets, swimming pools, museums and sports clubs.
But there have been challenges, including making sure people know about the network and that it reaches the most vulnerable. In 2022, only 15% of those in the low-income neighbourhood of La Prosperitat were aware of the shelters, according to a survey conducted by Terra Amorim-Maia. In 2023, they reached 30%, according to another survey conducted by the city council.
“So, in one year, the percentage of the population who knew about them had roughly doubled, but there were still 70% who did not,” she notes.
“Immigrants, mainly those from countries in the Global South, were seven times less likely to have ever heard of the climate shelter network [than those from the Global North].”
Women turned out to be more in need of shelters than men. “Men take more direct routes, from home to work, while women zigzag around the city because of their caregiving roles. They take the children to school, then stop by the pharmacy, go to the market, and so on,” adds Terra Amorim-Maia.
She says there are no studies on the cost-benefit of these spaces. But given that Barcelona’s network relies heavily on existing spaces that require little adaptation, “the benefit exists”.
Boston: many shelters, few visitors
In recent years, summers in the north-eastern US city of Boston have not only been warmer but also more humid, with four or five heatwaves per season.
While Barcelona learned from North America’s experiences, Boston in turn learned several things from Barcelona to improve its own network of cooling centres, says Zoe Davis, project leader at the Boston Office of Climate Resilience.
One was to add parks to the network, as the existing cooling centres were typically public buildings. Other spaces added included public libraries and free-to-use water play areas.
But who uses them, and how often, has proven difficult to determine. “That’s probably one of the hardest questions we’ve been trying to answer over the last two years. We have a registration process to keep track, but it’s very basic,” says Davis.
While they continue to work on a methodology that can better track attendance, Davis notes that some Bostonians say they prefer to stay cool in their own homes rather than utilise cooling centres. “We’ve had reports of underutilisation,” she says.
Now, green roofs are being installed at bus stops to reduce the impact of heat and bring more shelters closer to people.
Patricia Fabian and Jonathan Lee are researchers at Boston University’s School of Public Health and part of B-COOL, a joint initiative with the local government to monitor temperatures in different neighbourhoods.
“It’s clear that we need to have options for people who don’t have air conditioning in their homes, but it’s very difficult to see the impact that the measure [the cooling-centre network] has on health,” says Fabian.
She and her team have conducted studies evaluating the characteristics of the centres, but so far, there has been a lack of evidence on their effectiveness.
Meanwhile, Lee says they are working with the city government to analyse the budget allocated to the shelters in more detail. Their initial assessment is that too many resources are being spent on a measure that is not having the expected impact.
Failure or success?
Chelsea lies just across the Mystic River from Boston, and is administered as a separate city, although it is often labelled a suburb of its more famous neighbour.
There too the experience with cooling centres has been largely unsuccessful. The first centre was opened in a school early this decade.
When it first opened, a three-day trial was conducted, during which only one family used it on one day. More shelters were subsequently opened, but those also failed to attract large numbers.
“People tend to go to places they already have a connection with. If that’s not there, it’s hard for them to say: ‘I’m going to go there just to use the air conditioning and cool off’,” says Flor Amaya, the city’s director of public health.
Even so, Chelsea plans to continue with the initiative for the time being.
Two cities where shelters have worked well are New Orleans in the south-eastern state of Louisiana and Phoenix in the south-western state of Arizona.
In the first case, as it is a city with recurring power outages due to hurricanes, the organisation Together New Orleans launched the Community Lighthouse initiative using a network of buildings equipped with solar panels to serve climate shelters. There are 15 “lighthouses”. Long-term, the group wants to reach 500.
Meanwhile, the city of Phoenix is located in the middle of a desert and its network of shelters is widely used. “There are a lot of people living on the streets who have nowhere to go when it gets really hot. I think Phoenix has done a better job of taking care of that vulnerable population than other places,” Lee says.
Buenos Aires: Simplicity above all
One of the first Latin American countries to implement climate shelters to mitigate the impacts of heat was Argentina. Buenos Aires has a network of 69 shelters, and Rosario has 87.
Patricia Himschoot, climate change manager for the city of Buenos Aires, says the project there began in 2017, during a talk with people from Barcelona and Bogotá at a C40 Cities climate leadership group event.
“We didn’t call them climate shelters, but we talked about a place where people could go when it was very hot,” she recalls. The Buenos Aires network has open and closed spaces, such as museums, parks, libraries and nature reserves. All are identified with a sign outside and checks are made that they meet minimum requirements, such as thermal comfort.
Officials are currently working to expand the network and have held citizen participation workshops to listen to local needs. Businesses were offered the chance to open their buildings as shelters. “We also offered it to several companies, but they are not yet ready to take it on,” says Himschoot.
In the city of Rosario, located in the province of Santa Fe, the shelter idea emerged in 2022. The first examples were called “buffering centres” and designed to shelter homeless people. After learning about the projects in Spain, including Barcelona, officials broadened the target audience and changed the name to “climate shelters”.
Adaptation saves lives, and that is something we have to remember in the context of a climate crisisPilar Bueno Rubial, climate change undersecretary for the city of Rosario, Argentina
The first season in 2023-24 saw 25 shelters in public buildings offering basic amenities such as free access, drinking water, a rest area and information about the climate crisis. For the second season in 2024-25, the shelter organisers added almost 50 green spaces and incorporated drinking fountains for pets in some areas.
“We evaluated what had worked and what hadn’t, but we saw that there was a very high turnout [in both seasons],” says Bueno Rubial, the city’s climate change undersecretary. Work is now ongoing to expand coverage in the most vulnerable neighbourhoods and improve collection of usage data.
Another Argentine city that is beginning to work on its network of shelters is Mendoza. Researchers from the Institute of Environment, Habitat and Energy at the National Council for Scientific and Technical Research (CONICET) are preparing to install 12 climate shelters across the city. While other cities have utilised existing buildings and spaces, these shelters will be new 2×2 metre structures, similar to bus shelters.
They are designed to seat two adults and two children, plus four standing adults, and feature a drinking fountain and mobile phone charging capability. The researchers are considering building them with recycled materials and hope to have the first prototype ready for next summer.
“The idea was to add spaces that remain open without time restrictions,” explains María Belén Sosa, a researcher at CONICET and one of the promoters of the project, which is funded by the Municipality of Mendoza. “Here, peak usage will be during siesta time, which is when public offices are closed,” adds Silvina López, the municipality’s environment coordinator.
“We believe the initiative has the potential to be replicated in different areas,” says Julieta Villa, head of the Climate Management Department for the city of Mendoza.
The idea of providing a space with a pleasant temperature for those seeking refuge from heat has spread to other Latin American cities such as Santiago, Chile, which has a network of 35 spaces that includes municipal buildings, parks and fire stations; and Medellín, Colombia, which designed a system of green spaces and vertical gardens that run through densely populated areas.
Adaptation saves lives
The experts Dialogue Earth spoke to say that despite some of their problems, it is essential that more cities implement shelters. “It is a measure that democratises a right: the right to live in cities, regardless of what each person has in their home,” says Sosa.
Lessons are continually being learned from existing networks.
“Any city can do it with the information and resources that are already available,” says Bueno. “And why should they do it? Because adaptation saves lives, and that is something we have to remember in the context of a climate crisis.”
As the world continues to warm, some form of shelter is something more and more people will need to protect their health.
