Columbia-Led Scientific Mission Researches Rapa Nui’s Wetlands

April 30, 2018

In March a team of scientists led by  William D’Andrea, Associate Research Professor at Columbia University’s Lamont-Doherty Earth Observatory (LDEO), embarked on a research expedition to Rapa Nui (Easter Island) to study its wetlands. This collaborative field team included LDEO’s Lorelei Curtin, Andrea Seelenfreund from Chile’s Universidad Academia de Humanismo Cristiano, Nicholas Balascio and James Van Hook from the College of William and Mary in Virginia as well as Raymond Bradley from the University of Massachusetts Amherst.

Supported by Ma’u Henua (the Rapa Nui community administering the National Park), Chile’s Forest Service (Conaf), the National Monument Council (CMN), and Isla de Pascua’s Technical Department of Heritage (Secretaría Técnica de Patrimonio), the team successfully collected sediment cores from the wetlands of Rano Kau, Rano Raraku, and Rano Aroi. These cores contain geological records that likely span the past 30,000 years on Rapa Nui, providing invaluable insights into climatic, environmental, and human land-use history.

Water is a precious resource on Rapa Nui, with increasing demands from agriculture, animal husbandry, and the growing tourism industry. Recent evidence suggests that water availability on the island has fluctuated significantly over millennia due to natural climate variations. Alarmingly, the lake at Rano Raraku—the renowned quarry from which ancient Rapanui people carved their iconic moai statues—has completely dried up, exposing the lakebed. This dramatic change has occurred within the past year or two, forcing the annual local swimming and boating competition to relocate to the ocean.

The research team aims to address critical questions regarding the historical dynamics of this lake: How often has it dried up in the past? Has it ever been deeper than in historical times? Is the current desiccation at Rano Raraku a result of anthropogenic climate change, or is it a temporary condition due to short-term climate variations? By analyzing the sediment layers, which accumulate year after year like pages of a book, researchers hope to gain insights into the climate conditions experienced by the ancient Polynesians of Rapa Nui.

The samples collected will be analyzed at the Lamont-Doherty Earth Observatory at Columbia University, focusing on molecular evidence of past climate and environmental changes. Researchers will specifically examine lipid biomarkers to quantify historical shifts in precipitation and human-landscape interactions. This field campaign is made possible through funding from Columbia University’s Center for Climate and Life, the Vetlesen Foundationthe Explorers Club of New York, and the College of William and Mary Reves Center for International Studies.

See album here. (Photographs by William D'Andrea).