Urban Heat Waves: Which Neighbourhoods Are the Most at Risk?

Heat waves are an increasing hazard for our health, especially in cities. But which neighbourhoods are the most at risk? And which will be more at risk in the future? The answer comes from an international group of researchers that took Madrid as a case study to identify the more vulnerable areas to rising temperatures.

The study – published in Earth’s Future – shows that the vulnerability level to heat waves can significantly change within city areas. This element depends on the distribution of specific population subgroups, such as the elderly, women and people with low socio-economic status.

‘When deciding how to distribute and where to focus actions to combat and mitigate of climate change in cities, it is essential to have detailed information on a local level, regarding single areas and neighbourhoods’ explains Raya Muttarak, professor at the Department of Statistical Sciences ‘Paolo Fortunati’ of the University of Bologna, one of the study’s authors.

‘For this reason - adds Iulia Marginean, researcher at CICERO (Center for International Climate Research, Oslo, Norway) and first author of the study – we have developed a method which, based on a series of spatial and demographic data, allows us to predict vulnerability levels to heat waves with a high geographical resolution’.

Today, we know that the increase in temperatures and heat waves is associated with an increase in diseases and premature deaths. We also know that more than a third of the deaths linked to high temperatures - which in 2023 were more than 47 thousand in Europe alone - can be attributed to climate change induced by mankind. In addition, we know that cities are hotter than the surrounding rural areas. If (to all this) we add the fact that urban areas will become more and more populated and the population will grow older and older, it is clear that it is necessary to adopt efficient measures to fight the effects of climate change.

To identify which are and which will be the most at risk areas, researchers have taken into account the main socio-demographic characteristics linked to an increased vulnerability to high temperatures. Among these, advanced age, female gender and low socio-economic status stand out.

The model was then applied to the case of Madrid: Spain is indeed one of the European countries with the highest mortality rate connected to high temperatures, and Madrid was hit by long-lasting heat waves this year, too.

‘From our analysis, it emerged that there are significant differences in vulnerability levels to rising temperatures among various city areas and even within single neighbourhoods’, says Muttarak. ‘The most vulnerable populations are in the most disadvantaged city areas and their condition is destined to worsen in the coming years. That is unless focused interventions are put in place to promote a sustainable trajectory able to reduce vulnerability dynamics in favour of a more uniform and resilient change’.

To give an example, the analysis highlighted the El Goloso case. El Goloso is a peripherical neighbourhood located in the north of Madrid, which is mainly populated by elder people: data show that 73% of its population is above 65 years old. This makes El Goloso the most vulnerable area to high temperatures regarding the age parameter. However, if we consider the socio-economic status, the most vulnerable areas are neighbourhoods such as Villa de Vallecas, located in the south-east of Madrid.

‘To reduce the vulnerability connected to heat waves, it is essential to follow a sustainable development path designed to rapidly decrease emissions’, concludes Marginean. ‘In this case, the most efficient solutions are those specifically involving the social groups more affected by the negative effects of climate change and increasing their resilience ability’, concludes Muttarak.

The study was published in the journal Earth's Future under the title ‘High-resolution Modelling and Projecting Local Dynamics of Differential Vulnerability to Urban Heat Stress’. The University of Bologna was represented by Raya Muttarak, professor at the Department of Statistical Sciences ‘Paolo Fortunati’ and Principal Investigator of the project ERC-Consolidator POPCLIMA - Population Dynamics under Global Climate Change.