Historical and future losses of terrestrial ecosystem carbon stocks induced by urbanization in China from 1990 to 2100 under SSP scenarios

Urban expansion is a significant source of carbon emissions, making accurate assessment of associated terrestrial carbon stock losses essential. However, few studies have integrated localized datasets into the shared socioeconomic pathway (SSP) framework to comprehensively evaluate ecosystem carbon stocks, especially concerning secondary land use classes and disaggregated carbon pools. This study employs the InVEST model with the GLC_FCS30 dataset—featuring 29 detailed land use categories—to quantify the impacts of urban expansion on terrestrial carbon stocks in China from 1990 to 2020, and to project future losses under different SSP scenarios through 2100. From 1990 to 2020, urban expansion caused a total terrestrial carbon stock loss of 566.65 Tg, with carbon loss accelerating faster than the rate of urban expansion. The spatial center of carbon loss gradually shifted northwest. Between 2021 and 2100, projected losses range from 84.42 to 153.86 Tg C, with stabilization years in SSP1–SSP5 occurring in 2075, 2100, 2100, 2098, and 2081, respectively. Across all scenarios, carbon loss is primarily attributable to urban encroachment on both croplands (47.42 %–58.82 %) and forests (19.87 %–30.30 %). Collectively, these two processes account for 67.29 %–89.12 % of the total carbon loss. Developing urban agglomerations contribute more significantly and persistently to carbon loss than mature ones. This study offers a refined methodological framework and robust data for assessing carbon stock losses driven by urban expansion in China. It underscores the spatial and typological heterogeneity of carbon impacts and provides scientific insights for formulating sustainable urban development strategies. • China's terrestrial carbon loss due to urban expansion from 1990 to 2100 is quantified. • InVEST integrates 29 land-cover types and carbon densities under SSP scenarios. • Croplands and forests are identified as the main contributors to urban expansion-driven carbon loss. • Emerging urban agglomerations cause greater and longer-lasting carbon depletion. • Soil carbon dominates total carbon loss, contributing over 84 %.