This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Urban heat adaptation will gain in importance as climate change progresses. Researchers at the Karlsruhe Institute of Technology (KIT) have analyzed how sociodemographic factors (nationality, age, and rent) correlate with heat exposure throughout Germany.
The clearest correlation involves nationality: In 84.2% of the analyzed cities, the air was significantly warmer at night in areas with a higher share of residents without German citizenship. The data show clear spatial differences in intra-city temperature but allow no conclusions about their causes. The results have been published in Environmental Research Letters.
According to the EU's Earth observation program Copernicus, June and July 2026 were warmer than any other two-month period on record. Climate change is exacerbating such extreme heat events, and the consequences are especially evident in cities, whose sealed surfaces and buildings store heat during the day and radiate it away at night. In addition, cities have less vegetation to provide shade and cool the surroundings through evaporation.
This urban heat island effect has been known for decades and is well researched. In contrast, there has been little analysis of the social distribution of heat stress. "Thus far we've known relatively little about which demographics are exposed to especially high temperatures in cities," said Dr.
Susanne Benz from KIT's Institute of Photogrammetry and Remote Sensing (IPF). "Our work also considers these differences from an environmental justice perspective, in other words, whether different demographics have different exposure to environmental stressors." This also involves the question of whether certain demographics are found more frequently in districts with high building density and fewer green spaces that lead to higher temperatures. In their project, the researchers analyzed all districts (Landkreise) and independent cities (kreisfreie Städte) in Germany, combining air and land surface temperatures (day and night) in the summer months from 2021 to 2023 to derive an aggregate temperature parameter.
To account for urbanization's specific impact on temperature, they determined the urban heat island intensity by comparing urban temperatures with those of neighboring rural areas with similar topography. They then correlated the temperature data with the results of the 2022 census, taking three sociodemographic factors into consideration: the share of the population without German citizenship, the share of people over 65 years old, and rent per person as a possible indicator of socioeconomic status. For each factor, they compared temperatures within each district for areas with the highest and lowest values.
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