Imagine walking along Ipanema beach on a summer afternoon. The sand is golden, there’s a cooling sea breeze, the shade of a parasol and a cold drink in hand. Now look up.
Clinging to the hillside just a few hundred metres away is Vidigal, one of Rio’s favelas in the Brazilian city. Here, thousands of people live in a heat trap with metal roofs, no parks and no formal public transport networks.
In nearby sprawling suburbs, families face the same suffocating nights and concrete pavements radiate heat long after sunset. If there are no cool public spaces to retreat to, no water fountains or drinking water sources to guarantee relief, extreme heat is inescapable.
Rio is far from alone. Last summer, Europe sweltered. Spain recorded highs of 46°C. Portugal hit 46.6°C. France experienced its second-hottest June since 1900. In the US, more than 150 million people faced extreme heat warnings. In south Asia, west Africa and Latin America, extreme heat is not just seasonal.
But the consequences of heat are not evenly distributed. They vary between countries, regions and neighbourhoods. Differences in demographics, infrastructure and capacity to adapt all shape how badly people are affected.
Our new study shows that this “systemic cooling poverty” is widespread yet unequal across 28 – predominantly developing – countries.
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Across the 3 billion people represented by our sample, nearly 600 million are experiencing severe levels of systemic cooling poverty. People in south Asia and sub-Saharan Africa bear the heaviest burden.
Yet countries facing similar extreme heat can highlight different outcomes. Indonesia and Bangladesh both face exposure to hazardous humid heat affecting almost their entire populations, but Indonesia’s stronger physical infrastructure and healthcare translate into lower levels of systemic cooling poverty.
In cities, vulnerability is shaped by physical infrastructure (buildings, streets, pipes and green spaces) and social infrastructure (services, institutions and support networks), both of which are distributed unequally. Poorer residents typically have less access to air conditioning, tree-shaded streets and parks, and insulated housing.
Cooling capacity is not just a matter of technology. Framing air conditioning as the answer to extreme heat is problematic. Access to air conditioning is extremely unequal across and within countries – most of the world’s population simply does not have it.
Air conditioning is also energy-hungry. It raises annual household electricity bills by more than a third on average. This strains power grids when demand for energy peaks. Increased demand for electricity accelerates the climate change driving the heat crisis, pushing outdoor temperatures even higher. The production and disposal of units carries its own environmental toll, with hazardous materials risking release into soil, water and air.
The biggest factors determining whether heat becomes dangerous are the conditions people are born into and live in.
Where you live, how your neighbourhood is built, whether there are trees or public drinking water nearby, how well ventilated your home is, whether your workplace offers protection, and whether public services respond to rising temperatures all shape survival. So do age, health, income, gender identity and discrimination, which can determine whose suffering is recognised and whose remains hidden.
Responses to heat are shaped by the social and physical environments people inhabit. In many places, air conditioning has displaced ancestral knowledge and intergenerational practices for living with heat, including ways of building, moving, eating, and resting developed over centuries. Losing those practices can leave people more exposed and less resilient.
Since 2020, as part of our cooling poverty project we have interviewed 80 people living in Rio’s low-income suburbs and favelas. Nineteen of these residents kept online heat diaries: writing records, collecting photos, drawings, memes and voice notes, of their daily encounters with extreme heat.
Caregivers had to change their routines so domestic labour could be carried out in the cooler hours of dawn and dusk. Street vendors moved locations or abandoned certain routes.
For one resident with mobility impairments, cold showers, the most immediate cooling strategy, are not possible: “I would love to take four cold showers a day, but I have some logistic issues related to my condition.” Because they depend on air conditioning, their electricity bills triple in summer. For others, the beaches and waterfalls some people escape to remain out of reach: “I would love to go, but I can’t because of accessibility issues”.
For trans women residents, social discrimination closes off the very spaces (parks, squares, shops) where others find shade or a moment of cool. And because public bathrooms mean risking harassment, many limit how much they drink. Heat, for them, becomes a bodily danger with no safe exit.
Systemic cooling poverty is not about whether a person can afford air conditioning, but rather how surrounding infrastructure, institutions and design, expose someone to harmful heat and then fail to protect them from heat. It extends beyond the home to workplaces, schools and healthcare systems, where heat can have serious consequences for health, productivity and wellbeing. It reaches further into the systemic causes that determine who suffers most: inequality, discrimination, patriarchy, ableism and racism.
Heat vulnerability is not an accidental outcome. Urban planning decisions that remove green space, housing policies that allow poorly ventilated buildings, labour laws that leave outdoor workers unprotected, public health systems that fail among the most exposed all contribute.
Thermal justice
Reframing cooling poverty changes how researchers think about solutions. Thermal justice does not only mean reducing exposure to heat. It also means doing so fairly, and holding accountable the people and institutions whose policies and planning decisions have made some neighbourhoods hotter and some households less able to keep cool.
By asking “who designed these conditions?”, we can understand who has the power to change them.
Effective responses require coordinated action across urban planning, public health, housing and labour regulation: expanding access to safe water, retrofitting buildings and planting trees alongside reducing discrimination.
But the people most affected need to help design solutions. Their experiences reveal what heat actually feels like, day after day. By understanding and assessing systemic cooling poverty, we can identify how best to achieve thermal justice for those most at risk from extreme heat.
