Mapping Exposure to Sargassum Beaching Events for Insurance Risk Assessment in the French Caribbean

Since 2011, Sargassum beaching events have intensified across the western Atlantic, driven by the emergence of the Great Atlantic Sargassum Belt. These recurrent strandings generate environmental, economic, and health impacts in the French Caribbean islands, with growing implications for insurers due to disruptions of coastal activities, damage to infrastructure, and increased claims related to pollution and loss of use. In this context, Covéa conducts impact‑oriented studies to better understand how emerging environmental hazards may affect insured assets.

This study examines the long‑term evolution of Sargassum presence around Guadeloupe using satellite observations from the SAREDA dataset (Descloitres et al., 2021 ; Podlejski et al., 2022), provided by the AERIS/ICARE Data and Services Center. MODIS‑derived Sargassum fractional coverage was analyzed from 2003 to 2025 within a 50 km coastal buffer to identify the onset and magnitude of the post‑2018 regime shift. Results show a clear transition from low‑intensity occurrences before 2018 to increasingly severe and frequent events afterward.

To assess potential exposure of insured properties, a geospatial analysis was performed combining building location data, distance‑to‑shore metrics, and recurrent Sargassum accumulation zones derived from satellite observations. This approach identifies residential areas most likely to be affected by future beaching events and provides a first estimate of the associated insurance‑related risks.

This work contributes to a better understanding of Sargassum dynamics in the French Caribbean and supports insurers in integrating emerging environmental hazards into risk assessment and portfolio management strategies.

 

References

AERIS/ICARE Data and Services Center (2021) – SAREDA dataset. DOI: https://doi.org/10.12770/8fe1cdcb-f4ea-4c81-8543-50f0b39b4eca - last access : 2026/01/15

Descloitres, J., Minghelli, A., Steinmetz, F., Chevalier, C., Chami, M., & Berline, L. (2021). Revisited Estimation of Moderate Resolution Sargassum Fractional Coverage Using Decametric Satellite Data (S2‑MSI). Remote Sensing, 13, 5106. https://doi.org/10.3390/rs13245106

Podlejski, W., Descloitres, J., Chevalier, C., Minghelli, A., Lett, C., & Berline, L. (2022). Filtering out false Sargassum detections using context features. Frontiers in Marine Science, 9:960939. https://doi.org/10.3389/fmars.2022.960939