Nan Madol’s earlier construction dates align with climate-induced sea level changes, influencing both its development and decline, and offering lessons for today’s coastal management.
A new study provides revised dates for the construction of an ancient site in the Pacific, revealing that they correlate with sea level rise and El Niño-Southern Oscillation (ENSO) variability. The site, Nan Madol, is a monumental complex, built from stone and coral rubble on the Pacific Island of Pohnpei. Nan Madol was the administrative and cultural center of the Saudeleur Dynasty. The exact dates of construction had been unclear, obscuring possible links between the history of the site and climactic changes.
To refine the site’s chronology, Chuan-Chou Shen and colleagues used uranium-thorium dating for 167 coral samples and carbon dating for 18 charcoal samples. The dates reveal two major construction phases: the first from the 10th–12th centuries and the second from the late 12th to the early 15th century. These dates are centuries earlier than previous estimates.