Comparing land surface temperature and air temperature for assessing socio-demographic inequalities in urban heat exposure: evidence from Germany

Urban heat exposure is a growing public health concern, exacerbated by climate change and rapid urbanization. While the drivers of urban heat are well-studied, social disparities in exposure—a core environmental justice (EJ) concern—remain understudied. Existing EJ studies in urban heat typically rely on either land surface temperature (LST) or air temperature, although these two capture different aspects of urban heat. In this study, we compare both metrics to assess socio-demographic inequalities in heat exposure, across multiple spatial contexts and diurnal periods, using Germany as a national case study. We combine temperature data with census information to quantify disparities across urban, suburban, and rural districts and examine whether specific population groups are disproportionately exposed to higher temperatures. Our analysis reveals consistent inequalities associated with nationality, with foreigners disproportionately residing in hotter neighborhoods. More than 84% of cities show significantly higher night time air temperatures in districts with higher shares of foreigners, while more than 50% of cities exhibit significant disparities against foreigners for both LST and air temperature. ... mehrDifferences between daytime and nighttime patterns and between LST and air temperature highlight the importance of metric choice when assessing heat exposure and EJ. Our findings highlight areas of heightened vulnerability and provide insights for targeted mitigation strategies, contributing to equitable urban planning in the face of rising temperatures.