In the latest call to address rising sea levels, new research predicts that seasonal waves could reach Ahu Tongariki, the iconic ceremonial platform that is part of the Rapa Nui National Park, a UNESCO world heritage site, and home to the iconic moai statues, by the year 2080.

According to a new study led by researchers from the University of Hawai’i at Mānoa and now published in the Journal of Cultural Heritage, with the inclusion of the statues this coastal flooding threatens 51 cultural assets in the area.

“This research reveals a critical threat to the living culture and livelihood of Rapa Nui,” said Noah Paoa, lead author of the study and doctoral student in the Department of Earth Sciences in the University of Hawai’i at Mānoa School of Ocean and Earth Science Technology.

“For the community, these sites are an essential part of reaffirming identity and support the revitalisation of traditions. Economically, they are the backbone of the island’s tourism industry. Failure to address this treaty could ultimately endanger the island’s UNESCO world heritage site status.”

Threats to sites of cultural significance and their assets are equally as important to document as those to infrastructure as authorities work to develop plans to preserve and protect what matters to communities at greatest risk of rising sea levels. The ability to support thriving communities remains fundamental to the aims of ongoing studies into the impacts of those rising levels.

For this study, Paoa and his team built a detailed digital twin of the study site and used advanced computer models to simulate the wave environment along the coastline. They then mapped the projected flooding caused by waves under future sea level rise scenarios.

The flood extent was then overlaid on geospatial layers containing the location of cultural assets provided to the team by local partners, which allowed the researchers to identify the cultural assets that will be flooded.

“Unfortunately, from a scientific standpoint, the findings are not surprising,” said Paoa. “We know that sea level rises pose a threat to coastlines globally. The critical question was not if the site would be impacted, but how soon and how severely. Our work aimed to set potential timelines by which we could expect the impact to happen.

“Finding that waves could reach Ahu Tongariki by 2080 provides the specific, urgent data needed to incentivise community discussion and planning for the future.”

Notably, the challenges facing Rapa Nui mirror those being faced by other coastal areas around the world, including across Hawai’i. 

“While Hawai’i is invested in protecting coastal infrastructure from sea level rise, the irreplaceable coastal cultural heritage sites in Hawai’i and across the Pacific face the same urgent threat,” Paoa added. “Our research in Rapa Nui serves as a vital blueprint, demonstrating how we can use science to forecast risks to sacred places, such as coastal heiau and ancestral burial sites.

“By developing and applying these methods, we hope we can protect what is precious to the people of Hawai’i – provided such work is guided by, and deemed appropriate by, the Native Hawaiian community.”

With this in mind, Paoa and his team are now using available data on coastal flooding to examine the potential sea level rise impacts on cultural assets in Hawaii. In the future, he and the research team – in collaboration with local partners in Rapa Nui – plan to further investigate potential impacts of sea level rise on the island’s coastal cultural assets and examine adaptation and mitigation efforts to safeguard the cultural heritage.

The paper – entitled ‘Impacts of sea-level rise and wave inundation in the Tongariki Complex, Rapa Nui’ – is now published in the Journal of Cultural Heritage.

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