The role of enhanced organic carbon burial in the Bengal Fan in the late Cenozoic global cooling

Over the past five million years, Earth’s climate changed from a relatively warm state to one marked by permanent ice in the Northern Hemisphere and repeated ice ages. This transition is linked to a decline in atmospheric carbon dioxide. However, the natural processes responsible for that decline remain uncertain. This project quantifies organic carbon storage in marine sediment in the Bengal Fan. Much of this sediment eroded from the Himalayan mountains and contains organic carbon derived from plants. Burial of these plant-derived compounds in sediment removes carbon dioxide from the atmosphere. Results will improve understanding of how Earth’s natural carbon cycle regulates atmospheric carbon dioxide over long time periods, with relevance to ocean systems, carbon storage, and the processes that shape Earth’s habitability. This project will support a graduate student and publish educational materials including web-based videos, animations, and classroom resources. The project will reconstruct changes in organic carbon burial in the Himalaya–Bengal Fan sedimentary system over the past five million years. The central goals are to determine whether organic carbon burial in the Bengal Fan increased enough to alter the global carbon cycle and to identify the environmental mechanisms controlling this change. The research will use sediment cores collected during International Ocean Discovery Program Expedition 354 along a transect across the Bengal Fan. The investigators will measure organic carbon concentrations, sediment composition, grain size, mineral provenance, molecular biomarkers, stable isotopes, and organic matter reactivity to quantify carbon burial rates and evaluate organic matter source and degradation history. These measurements will be combined with sediment accumulation estimates, cosmogenic beryllium isotope constraints, and reconstructions of past monsoon rainfall and soil temperature. Together, these approaches will test whether increasing organic carbon preservation transformed the Himalaya–Bengal Fan system from a small carbon source into a major long-term carbon sink during the late Cenozoic cooling. 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. NSF Award ID: 2603262 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Valier Galy | Institution: Woods Hole Oceanographic Institution, WOODS HOLE, MA | Award Amount: $652,011 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2603262 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2603262.html