Urbanization-driven and intercity interaction-induced warming effects in the Beijing-Tianjin-Hebei urban agglomeration: A comparison of heatwave and non-heatwave scenarios

Urbanization-driven land use and cover change exacerbates urban warming and amplifies the effects of global climate change, particularly in interconnected urban agglomerations. This study utilized the Weather Research and Forecasting (WRF) model coupled with an Urban Canopy Model (UCM) to investigate how urbanization and intercity interactions influence urban warming during the summer season in the Beijing-Tianjin-Hebei (BTH) urban agglomeration, with a specific emphasis on whether the warming effect of urbanization exacerbates under heatwave scenarios. The results showed that from 2010 to 2020, the expansion of urban areas in the BTH urban agglomeration from 2259.81 to 3964.80 km² led to a 0.406 °C increase in 2-m temperatures (T2) in typical summer. Heatwave further exacerbated the warming effects in the urban agglomeration, with T2 rising by 0.648 °C during heatwave periods compared to 0.308 °C during non-heatwave periods. Major cities like Beijing and Tianjin significantly contributed to the warming of the entire urban agglomeration and other specific cities during heatwave periods. These findings underscore the need for collaborative urban planning to mitigate heat-related risks and manage compounded effects of urbanization and heatwave.