China’s ocean carbon sink capacity and its spatial spillover effects in the context of carbon neutrality

Purpose As a critical component of the global carbon cycle, ocean carbon sinks under the “carbon neutrality” target require scientific estimation of regional capacities and exploration of their spatial correlations. These efforts serve as an essential basis for formulating differentiated carbon sink development policies. This study aims to measure China’s ocean carbon sink capacity (OCSC) in the context of carbon neutrality and to investigate its spatial spillover effects. By revealing regional disparities and cross-regional dependencies, the research provides a scientific basis for formulating differentiated and coordinated policies to enhance ocean carbon sequestration. Design/methodology/approach Based on panel data of blue carbon ecosystems in 11 coastal provinces of China from 2008 to 2022, this study measures China’s ocean carbon sink capacity and employs a spatial econometric model to analyze the spatial spillover effects of various influencing factors. Findings Local governments should fully consider the integrity of ocean ecosystems and regional disparities when formulating ocean carbon sink policies, further coordinating interregional factors to enhance carbon sink capacity. (1) China’s total OCSC showed a consistent upward trend from 2008 to 2022, with salt marshes becoming the dominant contributing system. Regionally, the capacity ranked Eastern Ocean Economic Circle > Southern Ocean Economic Circle > Northern Ocean Economic Circle, with significant inter-provincial heterogeneity. (2) The global Moran’s I exhibited an inverted U‑shaped pattern, indicating significant positive spatial autocorrelation. Local indicators confirmed that high‑high and low‑low clusters dominated. (3) Spatial spillover effects revealed that ocean technology innovation, environmental regulation, and economic development generated significant positive cross‑regional impacts, whereas ocean disasters and sea level rise produced negative spillovers. Ocean labor input had positive direct effects but insignificant indirect effects. Originality/value Local governments should fully consider the integrity of ocean ecosystems and regional disparities when formulating ocean carbon sink policies, further coordinating interregional factors to enhance carbon sink capacity.