Response of the Bohai Rim carbon storage to rapid urban expansion

Rapid urbanization in coastal areas has caused substantial changes in Land Use and Land Cover (LULC), leading to significant impacts on carbon storage in terrestrial and marine ecosystems. A comprehensive understanding of these impacts is crucial for the protection of regional ecosystems and the promotion of sustainable development. This study adopts an integrated land-sea perspective to investigate land use evolution in the Bohai Rim. It combines natural environmental and socio-economic factors in an innovative manner to assess the impact of urbanization on carbon storage. Utilizing long-term remote sensing data, we observed continuous seaward expansion in the Bohai Rim region from 1990 to 2020. The reclamation area per unit coastline reached 102.87 hm²/km, encroaching upon tidal flats and salt marshes (1619.55 km²). Carbon stocks decreased from 512.39 Tg C in 1990 to 484.99 Tg C in 2020, with more than half of the carbon storage in intertidal wetlands lost. Under the low-carbon scenario, seaward poldering is better controlled, and carbon stocks in ecological land use show an increase compared with 2020. As a typical land-sea interaction zone, changes in carbon storage in the Bohai Rim are influenced not only by natural factors but also by the combined effects of human activities, economic development, and policy interventions. Therefore, it is essential to strengthen the integration of ecological conservation, green development, and policy interventions to achieve sustainable management of regional carbon storage.