Divergent Thermal Feedbacks of Urbanization and Greening Modulate the Urban Heat Island in 21st-Century China

Urbanization and greening reshape the surface thermal environment, with opposing thermal effects on urban sustainability and population health. Here, we integrate multidimensional analysis and LightGBM models to quantify how urbanization and greening alter surface temperature and thereby modulate surface urban heat island (SUHI) dynamics across 325 Chinese cities from 2000 to 2025. Our study reveals that urbanization-induced warming is consistently strongest in neighboring rural areas, whereas vegetation-driven cooling intensifies sharply in urban areas during summer. These opposing thermal effects exhibit clear seasonal and diurnal asymmetries, with the strongest responses occurring in summer and during the daytime. Climatic factors emerge as the dominant drivers of surface thermal variability across the urban-rural gradient. Urbanization-induced warming was the dominant contributor to the mean SUHI intensity of 0.39 °C, whereas urban greening represented a cooling contribution share of approximately 31.83% during summer. This contrast between persistent urbanization-induced warming and seasonally concentrated vegetation-driven cooling reveals the constrained timing and spatial dependence of effective biophysical mitigation. Our findings clarify the dual and asymmetric roles of urbanization and greening in urban thermal dynamics and provide quantitative benchmarks for differentiated, climate-resilient planning.