Urban-rural disparities of carbon storage dynamics in China's human settlements driven by population and economic growth

China has experienced a rapid expansion of human settlement in both urban and rural areas over the past three de-cades. Regarding the impacts on carbon storage, previous studies that only focus on certain ecosystems cannot reflect urban-rural disparities, resulting in the carbon storage changes in human settlement remaining unknown. In this study, we aimed to explore China's urban-rural disparities in human settlement expansion and direct impacts on carbon stor-age by using the big Earth data technology. The results showed that from 1990 to 2018, the total amount of China's human settlement expansion reached 175,703.80 km2, and the inner-city, peri-urban, and rural components ac-counted for 21.00 %, 20.18 %, and 58.82 %, respectively. Along with the general tendency of impervious surface area (ISA) growth, there was more soil organic carbon (SOC) (1254.33 TgC) being sealed beneath ISA (0-100 cm depth), compared to a huge reduction in vegetation biomass carbon (VBC) (91.44 TgC) during the study period. The results further indicated that the change density of either VBC or SOC presented a slightly rising trend along the urban-rural gradient, due to the increasingly common encroachment on vegetation and soil types with higher car-bon content. We also found that socioeconomic drivers had a greater influence in urban areas than rural areas, and the related correlation exhibited a descending trajectory in both urban and rural areas. There is thus an urgent need to pre-serve lands with abundant carbon storage and contain the waste of land resources in rural areas. All stakeholders should pay more attention to concerted and targeted regulation policies for well-planned and eco-friendly human set-tlement expansion such as enhancing rural land use efficiency and promoting large-scale afforestation and continuous

Automated summary

China has experienced rapid human settlement expansion in both urban and rural areas over the past three decades. However, previous studies have failed to capture the carbon storage changes in human settlement due to their focus on specific ecosystems and neglect of urban-rural disparities. This study used big Earth data technology to explore China's urban-rural disparities in human settlement expansion and their direct impacts on carbon storage. The results showed that China's human settlement expansion reached 175,703.80 km2 from 1990 to 2018, with different proportions in inner-city, peri-urban, and rural areas. The increase in impervious surface area led to a sealing of soil organic carbon and a reduction in vegetation biomass carbon, and the change density of both carbon components slightly increased along the urban-rural gradient. Socioeconomic drivers had a greater influence in urban areas, and concerted efforts are needed to preserve lands with abundant carbon storage and regulate rural land use to prevent wastage of land resources.