The Baffin Bay Deglacial Experiment (BAD-Ex): Spatiotemporal Observations of the Last Demise of the Greenland Ice Sheet.

During the last glacial maximum (LGM), the western margin of the Greenland Ice Sheet (GIS) extended hundreds of kilometers into Baffin Bay, was grounded near the continental shelf break, and was likely stabilized by fringing ice shelves and perennial sea ice. By the early Holocene, the GIS had largely retreated to within the current coastline. Whether a warming atmosphere, warming ocean, or some combination of the two, is responsible for GIS retreat is unclear. To address these questions the NSF-supported Baffin Bay Deglacial Experiment (BAD-EX) proposes a 35-day oceanographic expedition to four West Greenland trough mouth fan systems that comprise a 1000 km north-south transect of Baffin Bay. Slope deposits in these depositional environments will be examined using seafloor and sub-seafloor imaging techniques and by collecting sediment cores that span the LGM to present. Biological, magnetic, geochemical, and physical properties from the sediment records, set within a multi-proxy regional chronostratigraphy, will be used to test our primary hypothesis; that increasing ocean temperature at the base of marine terminating glaciers is a major driver of ice-sheet instability. The project will establish: 1) the timing and extent of warm Atlantic water incursion along the west Greenland margin; 2) the phasing of ice margin retreat and ocean change; and 3) the influence of regional geology, geomorphology, and ice dynamics on ice-margin retreat. Synchronous changes along the margin would point to the importance of warm subsurface Atlantic water as the primary driver of retreat. Asynchronous changes would point to the importance of other factors, including bathymetry, geomorphic configuration, ice dynamics, and external controls in driving change. The results will improve our understanding of the behavior of continental-scale ice sheets both in the past and the future. Early career leadership is at the heart of this project and graduate and undergraduate students will comprise half the sea-going science party. The BAD-Ex expedition will likely sail during the summer of 2022 or 2023. Prospective graduate students interested in seafloor mapping, paleo-ice sheet reconstruction, high-latitude paleoceanography, paleomagnetism, and/or chronological development are encouraged to contact the PIs at UF, UNCW, and OSU.