Evolution of ENSO during the Holocene

Columbia University, New York NY

Investigators

Abstract

Under this award the PIs will drill the reef at Tarawa Atoll (1N, 172E) in the central tropical Pacific in attempt to reconstruct El Nino/La Nina (ENSO) variability over the past 10K years. The PIs propose to measure sea surface salinity and temperature based on the 18O geochemical proxy. The PIs pilot study at Tarawa Atoll shows that typical ENSO events occurred as early at 7,760 years before present, during a time when some researchers say they did not detect evidence for ENSO in Ecuador lake sediments. ENSO tropical Pacific ocean/atmosphere anomalies are a dominant source of global climate variability, sometimes having catastrophic consequences. Instrumental data and intermediate and coupled models indicate that decadal and possibly millennial-scale sea surface temperature variability in the tropical Pacific have similar anomaly patterns to the El Nino/La Nina anomaly fields. A remarkable finding that the ENSO fluctuations of ocean/climate change were absent in terrestrial climate proxy records between 5,000 and 12,000 years before present has sparked new research in the ENSO modeling and paleoceanographic communities. Climate data for the past century show that some regions have changed their climate response to ENSO, as the frequency and intensity of tropical Pacific anomalies changed.