The Effects of Urban Land Expansion Intensify Climate Extremes in China’s Urban Agglomerations

The rapid expansion of urban land is considered one of the primary factors contributing to the enhancement in climate extremes in both frequency and severity. But the effects of urban land expansion on climate extremes are presently unclear, especially in geographically and climatologically complex China. This study investigates evolution laws of temperature and precipitation extremes from 1960 to 2022 over five national-level urban agglomerations in China and explores evolution trends in those under urban land expansion using the WRF model. The results show that the variation characteristics of temperature extremes over urban agglomerations in China show higher consistency compared to precipitation extremes under global warming and urbanization. Both the intensity and frequency of temperature extremes have significantly increased, but those of precipitation extremes have sometimes decreased rather than increased. Furthermore, both temperature and precipitation extremes will strengthen with urban land expansion. Around 30% of the enhancement in temperature and precipitation extremes can be attributed to urban land expansion. The temperature extremes of urban agglomerations at lower latitudes are more significantly affected by urban land expansion, but no significant spatial distribution law is observed in precipitation extremes. The results of this study could provide a scientific reference for better coping with extreme climate changes in urban areas and achieving sustainable development.