AIS-based spatiotemporal carbon emission reduction potential of coastal shipping in China

Reducing shipborne carbon emissions is essential for achieving global decarbonization goals and improving coastal environmental management. This study develops an integrated framework combining AIS data with the STEAM model to quantify ship emissions in China's coastal waters and evaluate their spatiotemporal characteristics and carbon reduction potential. A standardized AIS data processing approach was established to estimate emissions from main engines, auxiliary engines, and boilers, with uncertainties controlled below 6%. Results show that total ship emissions increased by 75% from 2021 to 2023. Regionally, emissions continued to grow in the Yangtze River Delta, stabilized in the Pearl River Delta, and changed only slightly in the Bohai Rim. Spatial analysis indicates that emissions were highly concentrated in major hub ports, particularly Shanghai and Ningbo-Zhoushan. Significant regional heterogeneity was identified in carbon reduction potential, with the Yangtze River Delta exhibiting the highest mitigation potential, followed by the Pearl River Delta, while the Bohai Rim showed relatively limited potential. These findings provide scientific evidence for developing region-specific emission reduction policies and sustainable management strategies for China's maritime sector.