Implications of anomalous relative sea-level rise for the peopling of Remote Oceania

Anomalous relative sea-level rise challenges the understanding of early human settlement in Remote Oceania. Research reveals that Pohnpei and Kosrae, home to UNESCO World Heritage Sites Nan Madol and Leluh, experienced a ~4.3-meter rise over 5,700 years due to subsidence, contrary to the expected sea-level fall. This finding suggests early settlements may lie undiscovered beneath current sea levels, prompting a reevaluation of migration pathways and monument construction. The study used radiocarbon-dated mangrove sediment to reconstruct sea levels, indicating that Nan Madol and Leluh were likely built on higher ground rather than as islets separated by canals, making them more vulnerable to future sea-level rise.

Sefton, J. P., Kemp, A. C., Engelhart, S. E., Ellison, J. C., Karegar, M. A., Charley, B., & McCoy, M. D. (2022). Implications of anomalous relative sea-level rise for the peopling of Remote Oceania. Proceedings of the National Academy of Sciences, 119(52). https://doi.org/10.1073/pnas.2210863119