Mitigation of urban heat island in China (2000-2020) through vegetation-induced cooling

City afforestation serves as a robust strategy for thermal mitigation. Employing multisource satellite data, we explored the impact of vegetation cover on temperature dynamics across urban and rural sectors in Chinese cities. Our analysis reveals that a 1 % increase in vegetation coverage corresponds to a reduction in surface temperature by 0.099 degrees C to 0.102 degrees C in urban environments. However, the cooling effect diminishes from urban to rural areas, where increased vegetation occasionally results in warming. Further, the temperature reduction tends to stabilize at higher vegetation levels, as demonstrated in grid-based evaluations. Significantly, variations in urban population density substantially modulate these cooling effects. Over the period 2000-2020, afforestation increased vegetation coverage by 4.35 % in urban areas, which led to cooling in 67.43 % of the analyzed cities, with an average surface temperature decline of 0.58 degrees C. Additionally, our findings document a notable attenuation of the urban heat island (UHI) effect over time, with an average decrease of 0.56 +/- 0.35 degrees C. This reduction primarily results from the thermoregulatory effects of changes in vegetation coverage, which cool urban areas and may warm rural ones. Our study underscores the critical role of afforestation in urban climate management and its efficacy in attenuating urban heat waves and UHI effects.