Economic impacts of sea level rise on China's coastal provinces under different adaptation strategies

As a country with some of the world’s largest and most economically dynamic coastal regions, China faces rising threats from sea level rise. However, the lack of high-resolution, quantitative assessments of sea level rise impacts for China limits the development of effective adaptation policies in a region critical to global economic stability. To address this gap, this study refines and applies the Python Coastal Impact and Adaptation Model (pyCIAM) to evaluate multiple adaptation options along China’s segmented coastline. The model integrates coastal elevation, sea level rise projections, and capital and population trajectories to estimate economic impacts under different adaptation strategies. The results show that locally optimized adaptation strategies can reduce the cumulative losses by 2100 from 4.5 trillion USD under no adaptation to < 0.9 trillion USD nationwide. Flexible strategies that adjust in real time reduce losses by up to 86%, offering both responsiveness and cost-efficiency. The reduction in losses is especially notable in economically developed provinces such as Shanghai (95%), Jiangsu (91%), and Zhejiang (89%), where dense populations and high-value assets increase the benefits of effective adaptation. These insights emphasize the necessity for integrating China’s coastal economic and geographic details into adaptation strategies to optimize sea level rise responses and strengthen coastal resilience.