A national Blue-ESG index: measurement of marine sustainability

This study firstly develops a novel Blue-ESG framework to evaluate marine sustainability across 80 countries over the period 2000–2023. The findings reveal that global Blue-ESG scores follow a “slow rise–fluctuant decline” trend, with a marked decline after 2017, primarily attributable to geopolitical risks, de-globalization trends, and the COVID-19 pandemic. OECD countries demonstrate significantly higher Blue-ESG scores compared to non-OECD countries, largely due to stronger marine governance policies and greater investment. A continental comparison indicates that Europe and Oceania are leading in performance, while South America and Africa lag considerably behind. Asia and North America exhibit pronounced intra-regional disparities. These differences highlight global imbalances in marine economic capacity, environmental and ecological protection, innovation, and governance. This study not only presents the Blue-ESG framework at the national level for the first time but also offers both theoretical and practical foundations for assessing global marine sustainability.