Urbanization-induced disparity of extreme heat distribution in metropolitan Beijing

Abstract

Cities are facing more frequent, intense, and prolonged extreme heat (EH) due to climate change and urban heat island effects. While the urban-rural EH difference is well documented, intra-urban EH distribution and the influence of local urbanization trajectories remain largely unknown. Here, we use five EH indices derived from in-situ observations and a global seamless near surface air temperature dataset to measure the frequency, intensity and diurnal changes of EH in Beijing. We first evaluate the dataset’s reliability in capturing intra-urban EH variations, then investigate how EH correlates with urbanization trajectories based on changes in land use and population from 2000 to 2020. We employ linear regressions to quantify the spatial pattern of EH within the city and clustering algorithms to analyze the impact of urbanization on EH. We find a clear urban-rural EH gradient, with the annual values of frequency and intensity increasing by 207.8 % and 27.8 % toward the city center, while the diurnal temperature range decreases, limiting nighttime heat relief in downtown areas. This reverse pattern underscores the rising threat of compound EH throughout the day and night for urban residents. Additionally, EH disparities among groups categorized by changes in land use and population highlights disproportionate heat stress in densely populated neighborhoods. Our study offers new insights on understanding the intra-urban EH variations for heat stress mitigation and adaptation.