Urban heat islands and income inequalities: Evidence from French cities

During heatwaves in cities, urban heat islands (UHI) can occur that unequally affect different neighborhoods due to variations in their structures, the quality of their buildings, vegetation, and human activity. Some populations are particularly vulnerable, such as older adults, young children, and low-income households, all of whom have fewer options when exposed to an UHI. For the first time, in our paper, we present the first analysis of climate inequality with respect to UHI in France. We build and match finely localized data in nine of the largest French cities on the air temperature and vegetation in the neighborhoods as well as the density, heights, and periods of construction of its dwellings, and finally on the socioeconomic characteristics of the households. We find that the relationship between UHI exposure and income depends on their pre-existing spatial sorting. In cities like Paris where both affluent and low-income households reside close to the city center, the relationship between UHI exposure and income follows a U-shaped curve. In contrast, in cities like Lyon where affluent households live in rich suburbs, the exposure to UHI decreases with income. We also find that vulnerable households, defined by both age and income criteria, are slightly more exposed but far less able to renovate their dwellings or leave cities during heatwaves.