Forced Changes in Tropical Pacific Variability from Glacial Times to the Future

The El Niño Southern Oscillation (ENSO) is a dominant source of year-to-year variability in temperature and rainfall affecting many regions of the world. The response of ENSO to external forcing varies in different climate models. Therefore, it is critical to test the fidelity of those models with records of past ENSO behavior from archives such as corals and cave deposits. However, there are few records of ENSO variability from times such as the last glacial period and deglaciation when there were large changes in external climate forcing. This project will reconstruct ENSO and Tropical Pacific Decadal Variability (TPDV) with corals and cave deposits from Vanuatu, Solomon Islands, and the Philippines to reconstruct changes in ENSO and TPDV. The results will be compared to climate model simulations of glacial and deglacial time periods to analyze the physical mechanisms of interannual and decadal variability in the tropical Pacific. This project will improve understanding of ENSO and TPDV and has the potential to improve predictability of these phenenomena. The project includes support for postdoc and undergraduate participation in the research, and collaboration with University of the South Pacific (USP) and Vanuatu Meteorology and Geohazards Department (VMGD). The goal of the project is to measure geochemical changes in fossil corals from Vanuatu and speleothems from Vanuatu, Solomon Islands, and Philippines to reconstruct changes in ENSO and TPDV. The results will be compared to climate model output from the Community Earth System Model (CESM) 1.2 and analyze the physical mechanisms of TPDV changes and test the hypothesis that El Niño Southern Oscillation (ENSO) was reduced and TPDV was stronger during glacial times compared to preindustrial times. The project includes support for postdoc and undergraduate participation in the research, and collaboration with University of the South Pacific (USP) and Vanuatu Meteorology and Geohazards Department (VMGD). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.