Assessing marine disaster severity of coastal zones in China

China’s coastal zones are highly vulnerable to marine disasters, emphasizing the need to understand their spatiotemporal patterns to enhance disaster prevention and mitigation. Despite their significance, integrated assessments of disaster severity across coastal provinces remain limited. Storm surges, rough seas, sea ice, and red tides are the leading causes of economic losses and fatalities. This study systematically compiled a dataset of these four disasters in Mainland China (2000–2022). Each province’s comprehensive disaster severity index was derived using 15 variables with weights assigned through the entropy method. The results indicate that direct economic losses and fatalities have significantly declined since 2000. Coastal provinces along the Bohai Sea and Northern Yellow Sea are primarily affected by sea ice and storm surges. In contrast, those along the Southern Yellow Sea, East China Sea, and South China Sea face greater impacts from storm surges and rough seas. Storm surges cause the most economic losses, while rough seas lead to the highest fatalities. The comprehensive disaster severity index identifies Zhejiang Province (0.54), Fujian Province (0.45), and Liaoning Province (0.39) as the most severely affected provinces. These findings provide valuable insights for provincial-level marine disaster management, offering critical guidance for policymakers to strengthen mitigation strategies.