Deciphering the Subantarctic South Pacific Ocean’s Role in Pleistocene Climate Evolution with IODP Expedition 383 Sediments

The Southern Ocean is a key element of the global climate system. It is home to the Antarctic Circumpolar Current, the fastest ocean current on Earth. As a strong carbon sink, it represents an important shield against some of the effects of human-caused greenhouse gas emissions. However, the processes driving the Southern Ocean’s variability are still poorly known. This project will investigate the role of the South Pacific in the climate system over the past 2 million years. It will do so using sediment cores recovered during a recent drilling expedition on the Joides Resolution. The project will generate records of surface ocean conditions that can inform our understanding of the capacity of the ocean to take up carbon dioxide and store it in the deep ocean. The geosciences are the STEM field with the least participation from underrepresented minorities. The project will use a cohort student program to actively promote diversity and broadened participation. Under the guidance of a psychology professor, the project will create an environment that enhances engagement, learning and innovation through diversity. A goal of this cohort approach is to shift geoscience education from a style based on gatekeeping to one that that is inviting and supportive of people from diverse backgrounds.The climate science community’s understanding of Earth’s long-term climate evolution predominantly comes from Northern Hemisphere climate records. Given the central role of the Southern Ocean in the global climate system and its proximity to the Antarctic Ice Sheet, the Southern Hemisphere data gap severely inhibits our ability to understand global changes in ocean-atmosphere-ice sheet dynamics and carbon cycling during major climatic transitions. Records from the South Pacific are especially valuable to improve our understanding of these processes, because the Pacific contains by far the largest surface area and volume fraction of the Southern Ocean and therefore holds the largest capacity for carbon storage in the deep ocean. This project proposes to generate high-resolution climate proxy time series over the past 2 million years with emphasis across the Mid-Pleistocene Transition (MPT) using new sediment cores recovered during Expedition 383. These long records will explore changes in climate/carbon dynamics at the ocean surface by reconstructing dust input, nutrient utilization, and export production and these records will be synthesized and interpreted with collaborators’ records of sea surface temperature, water mass structure and circulation. Drawing from expertise across three US institutions, the project will produce an unprecedented suite of complementary biological and geochemical tracers at three drill sites (U1539, U1540, and U1541) in the Subantarctic Pacific.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.