Economic impacts of recent and future coastal inundation in Vanuatu

Small Island Developing States (SIDS) are highly exposed to extreme sea level (ESL) events, which are expected to intensify under climate change. Understanding the exposure and economic implications of ESL-driven coastal inundation is essential for informing risk reduction and adaptation planning. This study presents a scalable methodological framework for assessing exposure and economic impacts of ESL-driven coastal inundation on critical assets. The framework integrates high-resolution geospatial data, probabilistic return interval analysis, and climate scenario projections to quantify present and future coastal risk. Applied to Vanuatu as a case study, the framework evaluates exposure and replacement costs for buildings and road networks under 50- and 100-year ESL events, across baseline (1981–2020) and future climate conditions (2041–2060 and 2081–2100), assuming low (RCP2.6) and high (RCP8.5) greenhouse gas emission scenarios. Results indicate a substantial increase in both exposed assets and associated economic losses under future scenarios. For instance, the total replacement cost of buildings exposed to 50-year ESL events rises from USD 59 million (5 % of GDP) under baseline conditions to USD 97 million (9 % of GDP) by mid-century under high emissions, and up to USD 163 million (15 % of GDP) by late century. Comparable increases are evident for road assets, particularly in low-lying local government areas adjacent to major waterways. Beyond quantifying local impacts, this case study demonstrates how the framework can be adapted for regional and national coastal risk assessments to inform climate adaptation planning, infrastructure investment, and disaster risk management in other SIDS in the Pacific.