P2C2: Towards a Precipitation History of Easter Island Since the Last Glacial Period

Lead PI: Dr. William J. D'Andrea

Unit Affiliation: Biology and Paleo Environment, Lamont-Doherty Earth Observatory (LDEO)

September 2019 - August 2021
Oceania ; Pacific Ocean ; Easter Island
Project Type: Research

DESCRIPTION: In order to improve forecasts of multi-centennial-scale climate change, it is critical to document past regional responses of atmospheric processes to climate forcing. Meanwhile, although the southeastern Pacific is a region with important feedbacks in such global climate processes, there is currently a lack of high-resolution continuous records from this region that can be provided by archives in sedimentary records. This project will provide this important and novel perspective from past climates by using archives of precipitation changes recorded in wetland sediments on Easter Island. The researchers will provide a high-resolution chronology and preliminary records of past precipitation, which will help facilitate analysis of multi-centennial climate change to inform the causes, timing and magnitudes of natural climate variation in this globally critical region. The results will provide valuable information for water resource management on Easter Island, and the researchers will communicate results with water managers through narratives and widely available media-based outreach for communication of climate science through the lens of Easter Island.

Specifically, this project aims to develop continuous quantitative records of precipitation change on Easter Island to document changes in atmospheric circulation patterns in the SE Pacific spanning the past 30,000 years. There are currently no continuous data sets available from the heart of the SE Pacific to assess the evolution of atmospheric patterns in the region following the last glacial period or the character of multi-centennial-scale variability. The researchers will begin to develop compound-specific-isotope-based records of past precipitation from recently collected wetland sediment cores from Easter Island, and develop a precise and well-controlled chronological framework for these records. The project will also produce records for the Common Era, when Easter Island was occupied by the Rapanui culture. Cryptotephra analyses will reinforce 14C-based depth-age models during the period of human occupation. The objectives of the project are to 1) document and compare the patterns of SE Pacific atmospheric variability that characterized the last glacial and current interglacial periods, including differences in mean climatology and in the multicentennial- and millennial-scale variability, by generating continuous records of Easter Island rainfall for the past 30,000 years, and 2) document the precipitation changes on Easter Island that occurred in the centuries prior to, during, and following the settlement of Easter Island ca. 700-1000AD by ancient Polynesians, and throughout the rise and fall of the Rapanui culture during the second millennium AD.