Global warming and urbanization triggering the record-breaking heat event in summer 2023 over Beijing-Tianjin-Hebei urban agglomeration, China

Abstract

The summer of 2023 was characterized by record-breaking widespread heat with extensive impacts on agriculture, water supply, transportation and the socio-economy over Beijing-Tianjin-Hebei (BTH) urban agglomeration. Here, we present a timely, comprehensive, multi-faceted analysis of the 2023 extreme heat event based on six extreme heat indices(EHIs). Our findings indicate that the synergistic effect of global warming, urbanization and anomalous atmospheric circulation is the main cause for the occurrence of the record-breaking event. The EHIs have significantly increased during 1971–2023 over the urban agglomeration, especially since 21st century. The increasing magnitudes of EHIs in megacities (i.e., Beijing, Tianjin and Shijiazhuang) were much greater than in surrounding areas. The Urban Heat Island (UHI) effects contribute more than a half to the increase of EHIs. In addition, the intensified continental high-pressure and Western Pacific Subtropical High are favor to the occurrences of extreme heat event in the era of rapid global warming. With such record-breaking heat events becoming more frequent and intense under the rapid global warming and urbanization, we suggest that greening urban areas, designing cool rooftop and planning ventilation corridor could be the practical approaches to mitigate the UHI effect for climate change adaptation strategy.