Over the last half-century, the probability of extreme heat events has changed with magnitude orders in almost every region of the world, with events that are now up to a hundred times more than a hundred years ago . Of all-natural disasters, extreme high temperature events are the leading cause of weather-related mortality and are expected to be the leading cause of additional deaths due to climate change in the coming years.
In cities, the effect of a heat island creates higher temperatures than in areas with vegetation. But situations within urban areas are not the same in all their parts – either because of their physical form or because of the special needs or vulnerabilities of residents – so not all an area of a city as vulnerable to heat waves. Therefore, identifying those areas that are particularly at risk of heat is particularly important to implement interventions at a local level aimed at improving the capacity to address the impact of heat waves on the health of citizens.
The literature review “The heat health nexus in an urban context: A systematic literature review examining the socioeconomic vulnerabilities and features of the built environment”, published in the Journal “Urban climate” and led by the CMCC Foundation in collaboration with Ca ‘Foscari University of Venice, aims to examine what vulnerability factors determine the nexus between heat and health product in context urban. The analysis selected forty articles from the major literature on the subject, drawn from two well-known databases of peer-reviewed literature (Scopus e PubMed).
“At the heart of our research was consideration of interdisciplinary areas that are rarely combined in the same analysis,” explains Marta Ellena, CMCC researcher and lead author of the study. examines what factors can influence people’s vulnerability to heat stress, considering physical and mental health, demographics, social and economic status. In this analysis, we have also added these factors to the built environment characteristics, since the temperature mortality relationship does not occur in terrestrial voids. Rather, it is ‘rooted’ within urban fabric, depending on the particular contextual way in which natural, physical, and socio-economic processes interact. “
Through the concept of “enhanced disclosure”, the study notes how different aspects of the physical environment can exacerbate (or mitigate) climate impact in different locations across cities.
“Public exposure is certainly linked to the area’s physical exposure to heating. The built-up areas within the cities collect solar energy during the day and release it overnight. Thus, the urban contexts heat up and stay warm much more than the surrounding green spaces, even at night, which occurs to a greater or lesser extent based on the shape and the design “says Margaretha Breil, urban designer and researcher at CMCC. “But we can’t just consider the physical view: along with this phenomenon, called the“ heat island ”, there are other conditions that can make context more difficult to live in, and even more deadly “.
As the study shows, social disadvantage can exacerbate the risk of heat. Research cited in the paper found that heat wave-related mortality is higher where high levels of crime and social cohesion are low. On the other hand, it was found to be less for communities characterized by extended family ties that allow mutual care rather than forcing loneliness.
“The quality of life in cities is determined not only by the shape of the urban space, but also by its accessibility. If there is access to a green space, the quality of life of its citizens will improve. And this is true both during a pandemic, as we all see in the present, and during a heatwave ”explains Breil. “Nevertheless, if the green area is a place of crime or heavy traffic, it is as if it is there: those who are afraid to go out or do not enjoy being going out to live at home during a heatwave. And at home, the most vulnerable can even die “.
As the authors make clear, understanding these aspects and combining them in heat vulnerability registers may be crucial to identify and implement effective social and physical infrastructure measures by use of ad hoc spatial planning considerations and urban governance decisions.
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For more information:
Ellena M., Breil M., Soriani, S., The heat health nexus in an urban context: A systematic literature review examining the socioeconomic vulnerabilities and features of the built environment, 2020, Urban climate, DOI: 10.1016 / j.uclim.2020.100676
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