An ancient city built atop a coral reef — that’s the story of Nan Madol, once the seat of a dynasty in Pohnpei.
Nan Madol is of great cultural and historical importance, as it likely marks the earliest known example of centralized political power in the Western Pacific. The site in what is now known as the Federated States of Micronesia was designated a UNESCO World Heritage Site in 2016.
One of the great mysteries of Nan Madol is what caused the downfall of the Saudeleur Dynasty hundreds of years ago.
New research has a surprising theory: changes in climate and sea level rise.
National Taiwan University geoscience professor Chuan-Chou "River" Shen and his team sampled over a hundred corals that were part of various Nan Madol structures, including the palace, royal tomb and seawall compound.
They were able to date a period of frenzied construction activity to the 1400s and found that the people of Pohnpei were building up the seawall just as the island’s sea level was rising due to El Niño and La Niña events — a phenomenon known as El Niño–Southern Oscillation variability.
The study was published in the journal Proceedings of the National Academy of Sciences Nexus. HPR spoke with Shen about what Nan Madol’s history can tell us about our ongoing manmade climate crisis.
"We realized this is exactly a symbol for what we are facing now, especially for the islanders in the Pacific, Indonesia, Indian oceans," he said. "Now we are facing, because of global warming, sea level rise over 3 millimeters per year, and then we also experience a very heavy, severe ENSO variability."
Shen shared another enduring mystery of Nan Madol is how the people of Pohnpei transported the basalt stone tens of kilometers to use in the construction of their palace city. His theory? They floated them on canoes.
This interview aired on The Conversation on Oct. 9, 2024. The Conversation airs weekdays at 11 a.m. on HPR-1.
