High Resolution Reconstruction of Climate in the West Tropical Pacific Warm Pool from 26,000 Years Ago to Present: Stalagmites from Northern Borneo

California Institute Of Technology, Pasadena CA

Investigators

Abstract

This award will develop high-resolution records of precipitation variability in the West Pacific Warm Pool from 26,000 years ago to present using speleothem data from the island of Borneo. The research plan is designed to investigate decadal to centennial variability across select windows of the last 26,000 years ago, and to determine the structure and timing of rapid climate changes that occurred during the last deglaciation. The question of whether the tropical Pacific drives, or passively responds to, extra tropical climate change can be answered with these speleothem records. Speleothems collected from Borneo provide an opportunity to reconstruct sub-decadal hydrological variability in the West Pacific Warm Pool, an area where precipitation is heavily influenced by El Nino Southern Oscillation (ENSO) variability. Geochemical and optical analysis of a speleothem already in hand will be carried out in parallel with the collection and analysis of new speleothems. High-precision U/Th dates will provide age control for the geochemical climate proxy records, which will include oxygen isotopes, carbon isotopes, and Mg/Ca ratios. Micron-scale imaging techniques will be applied to the speleothem in the hopes of resolving annual variations in speleothem growth rate, which represents another potential precipitation proxy. A field program will provide samples that will be used to calibrate and test the reproducibility of the speloethem-based climate proxy records. Calibration efforts will include comparing ultra-high-resolution proxy reconstructions from the tops of actively growing speleothems to both instrumental and proxy climate data for the last millennium. A high-resolution record of climate through the Holocene back into the Pleistocene from the equatorial Pacific region will be an important addition to the paleoclimate data archive with multiple applications in the study of climate variability and impact.