As Spain braces for the first heatwave of the summer—with temperatures expected to reach 40°C across much of the country and tropical nights becoming widespread (minimum temperatures remaining above 20°C)—ongoing research by the Institute of Government and Public Policies at the Autonomous University of Barcelona (IGOP-UAB) confirms that exposure to extreme heat varies significantly between neighbourhoods. In Spain’s largest cities, living in a disadvantaged neighbourhood means, on average, experiencing higher temperatures than living in an affluent one. This is not an isolated phenomenon, but a systemic pattern observed in Barcelona, Madrid, Valencia and Seville, albeit with varying intensity..
The study, conducted as part of the ADIS (Adaptació al Canvi Climàtic en Barris Desafavorits) project, , analysed data from the exceptionally hot summer of 2022. The findings show that lower-income neighbourhoods, characterised by high urban density and large housing estates, consistently record the highest temperatures.
The researchers compared the Urban Vulnerability Index (UVI) developed by the Institut Metròpoli with two temperature indicators: Land Surface Temperature (LST), measured using satellite data, and the Universal Thermal Climate Index (UTCI), which estimates the actual thermal comfort experienced by people. Both indicators reveal a positive correlation between urban vulnerability and exposure to high temperatures.
Temperature gaps city by city
The study quantifies the temperature differences between vulnerable and non-vulnerable neighbourhoods. The largest disparities were found in Barcelona (+0.98°C in LST and +0.56°C in UTCI) and Valencia (+0.81°C in LST and +1.08°C in UTCI).
Madrid shows an intermediate gap (+0.58°C in LST and +0.42°C in UTCI). While these differences may appear modest, they are highly significant in terms of comfort and public health. A single degree Celsius can make the difference between a night during which the body is able to recover and a tropical night that places the cardiovascular system under constant stress.
In Seville, the pattern is considerably less pronounced: the gap is +0.35°C in LST and -0.09°C in UTCI. This is explained by the city’s greater intra-urban climatic homogeneity, where almost all neighbourhoods experience similarly high temperatures. Nevertheless, the overall trend remains the same.
More than 3.7 million people trapped in “hotspots”
The study identifies the neighbourhoods where social vulnerability and extreme heat converge. In each metropolitan area, the pattern is repeated under different place names but follows the same underlying logic:
- Barcelona Metropolitan Area: more than XXX,000 people living along the Llobregat and Besòs corridors.
- Madrid Metropolitan Area: more than 2 million people in the southern districts of the capital (Vallecas, Carabanchel and Usera) as well as in Móstoles, Leganés and Alcalá.
- Valencia Metropolitan Area: more than XXX,000 people in Torrent, Xirivella and Paterna.
- Seville Metropolitan Area: more than XXX,000 people in the south-eastern districts of the city and in Coria, Alcalá de Guadaíra and Los Palacios.
Overall, more than 3.7 million people across Spain’s four largest metropolitan areas live in neighbourhoods where social disadvantage and extreme temperatures combine most severely.
A call for targeted public policies
Recognising that heatwaves are no longer exceptional events but part of a new climatic reality, the researchers urge public authorities to act to prevent the most disadvantaged communities from bearing the brunt of increasingly extreme heat.
They advocate place-based positive discrimination, arguing that investment in climate shelters, urban tree planting, reflective pavements and housing improvements should be prioritised in these urban hotspots.
According to Marc Parés, Professor of Geography and lead researcher of the project:
“Initiatives such as the new Neighbourhoods Act in Catalonia represent a major opportunity to promote climate policies in the most vulnerable neighbourhoods.”
He adds:
“Urban regeneration policies should expand climate shelters and the limited green infrastructure currently available in these areas. They should also allocate resources to improve the energy efficiency of buildings and invest directly in housing in order to enhance residents’ living conditions.”
The adaptation gap deepens inequality
The study also warns that actual exposure to heat may be even greater than current measurements suggest. Residents of these neighbourhoods not only live in hotter environments, but also have far fewer resources to protect themselves from extreme temperatures.
- Many tenants are unable to install air conditioning.
- A significant proportion of residents work outdoors—in construction, delivery services or street cleaning—without access to cooling.
- Even where air conditioning is available, many households cannot afford the associated electricity costs.
In this regard, IGOP researcher Andrei Turlea states:
“The real exposure gap is much larger than what we are currently measuring. Residents of disadvantaged neighbourhoods not only live in hotter environments; many also spend their working day outdoors under the sun before returning home to dwellings that often become ovens.”
A structural pattern across Spain
The research, carried out across Spain’s largest metropolitan areas, demonstrates that this is not a phenomenon unique to Barcelona. In Madrid, more than two million people live under similar conditions in neighbourhoods such as Vallecas, Carabanchel and Usera. Valencia and Seville display the same pattern, with hundreds of thousands of residents living in historically segregated urban areas where heat is intensified.
Although the study is still in progress, the findings are being released now in light of the urgency of the current climate crisis.
IGOP-UAB is a research institute specialising in public policy. The ADIS project is funded by the Spanish Ministry of Science, Innovation and Universities.
