Urban form and surface temperature inequality in 683 European cities

• Size, population, morphology, land cover, topography, and climate are effective. • Population-weighted Gini coefficient of summer LST in 683 cities are studied. • Environmental inequality is present all across Europe. • The urban form explains a substantial part of LST inequality in European cities. • Urban form effects vary across the cities. Some effects are generalizable. Despite rapid urbanization and growing heat stress, comprehensive insights into the association between urban form and environmental inequality are lacking. We study the population-weighted Gini coefficient, the measurement of inequality, of the average land surface temperature (LST) in summer in 683 European cities (i.e. Functional Urban Areas) against thirty-four urban form indicators, i.e. population, area, compact ratio, local climate zones (LCZ), presence of grass, impervious surfaces, trees, water and albedo, elevation, aspect, Köppen-Geiger climate classification (KG) and latitude. We calculate density, Moran's I and Entropy measures to quantify cities' spatial structures and diversity. The area of each city is divided into 1 × 1 km spatial units, and inequality among such units is calculated. Using geographically weighted regression (GWR), we found that the impact of factors varies across the cities and that almost 70 % of overall inequality can be explained by urban form. The variables occasionally decreasing LST inequality were population density and concentration, LCZ 9, dry climate, and high latitude. The ones increasing it were urban size, LCZ 3, 5, 6, 8, entropy LCZ, impervious surfaces' density and concentration, trees, high elevation, aspect southwest, and polar climate. Ultimately, the study discusses the findings and proposes spatial strategies for mitigating inequality.