Unit Affiliation: Geochemistry, Lamont-Doherty Earth Observatory (LDEO)
This project's goal is to examine variations in dust deposition throughout the last 150,000 years in the west-central Pacific from a suite of ocean sediment cores recently recovered from the Line Islands Ridge and constituting a roughly north-south transect across the modern Inter-Tropical Convergence Zone (ITCZ) near 160°W longitude. During the interval of interest for the project, the Earth's climate shifted from full glaciation to one of the warmest interglacials in the last million years. Following that peak interglacial, global climate varied through multiple 20,000 year cycles while trending toward a return to full glacial conditions at the last glacial maximum (LGM) before the last deglaciation and Holocene interglacial. Windblown dust plays important roles in influencing and recording climate. In the atmosphere, dust contributes to the planetary albedo and serves as cloud condensation nuclei. In the ocean, dust may fertilize biological productivity through the addition of crucial trace nutrients, and provide ballast for the sinking of particles, thus enhancing carbon export from the surface ocean and drawing down atmospheric carbon dioxide. In deep-sea sediments, the amount, location and type of dust deposition provide clues for reconstructing its past sources, pathways, magnitude and removal processes. These removal processes include the shifting rain belts of the ITCZ that follows the thermal equator over the tropical ocean. The project will advance understanding of natural variations in climate, dust, productivity, and the hydrological cycle, and will promote training and learning for several early career scientists as well as undergraduate students. The research team will also leverage their research and education efforts in collaboration with middle school and high school science teachers through the Lamont-Doherty Earth Observatory's Earth2Class program.