Analysis of spatial and temporal characteristics and influence mechanisms of blue-green spaces in China’s, 2000–2020

• The spatiotemporal evolution of China’s blue-green space were analyzed. • The trend of blue-green space were analyzed using Theil-Sen slope and Mann-Kendall trend test. • The influencing factors of blue-green space were analyzed using optimal parameter geographical detector. • Three simulation scenarios were devised to predict the distribution patterns of blue-green space by 2030. Blue-green spaces are critical in mitigating climate challenges, preserving ecological equilibrium, and enhancing land quality. Previous research predominantly relied on traditional geographic detectors, focusing narrowly on the evolution of blue-green spaces within individual cities or provinces, while neglecting macro-scale investigations. This research employed a comprehensive approach to investigate the evolution patterns of China’s blue-green spaces from 2000 to 2020, utilizing the optimal-parameter geographic detector to elucidate the roles of its driving factors. Ultimately, three scenarios for the blue-green spatial distribution in 2030 were simulated. The results showed: (1) Based on land use data spanning two decades (2000–2020), the area of blue-green spaces had steadily diminished, contracting from 7,320,700 km 2 to 7,270,200 km 2 . (2) 99.35 % of areas exhibited no significant change in blue-green spaces, while a significant upward trend (0.40 %) was predominantly observed in the eastern region and a significant downward trend (0.25 %) was in the northern and western regions. (3) Both natural and anthropogenic factors contributed to the evolution of blue-green spaces. During the study period, the influence of human activities had intensified, and the combined effects of any two factors were greater than their individual contributions. (4) Across three developmental scenarios, the area of blue-green spaces continued inexorable decline, with areas projected at 7,163,800 km 2 (natural development), 7,180,700 km 2 (ecological protection), and 7,093,800 km 2 (urban development) respectively. This study not only unravels the intricate processes and pivotal influencing factors governing the evolution of blue-green spaces but also furnishes critical quantitative evidence for safeguarding and planning these essential spaces.