Unpinning of the Ross Ice Shelf from Ross Bank

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The Antarctic ice shelves are created when glaciers from the interior of Antarctica flow beyond the edges of the continent and extend into the oceans. These ice shelves can act as a buttress that limits the flow of ice from the interior of the continent to the oceans. The resulting loss of buttressing ice likely causes an acceleration of ice-streams transporting ice to the oceans causing negative ice mass balance and global sea-level rise. Thus, the high rates of Antarctic ice shelf thinning are a major concern. The extent of these thick ice shelves is often controlled by subglacial topographic highs or pinning points such as offshore islands and/or submarine banks which tend to slow the offshore discharge of interior glacier ice. The detachment of ice shelves from pinning points may lead to rapid ice shelf retreat reducing buttressing. The questions remain, how might modern-day ice shelves decouple from these pinning points and how would offshore flow of ice volume re-organize after an ice shelf unpins? This project acquires sediment cores and sea floor surveys from the Ross Sea that will be used to generate a detailed reconstruction of how and when the Ross Ice Shelf (RIS) unpinned from a submarine bank in order to gain perspective on the current stability of the West Antarctic Ice Sheet (WAIS) and the potential for a future disruption of the Ross Ice Shelf should it detach from existing pinning points including Roosevelt Island.The research investigates the how, why and when the Ross Ice Shelf (RIS) unpinned from Ross Bank to assess ice sheet and ice shelf behavior during a recent unpinning event. Changes in West Antarctic Ice Sheet flow patterns as suggested by flow stripes and rift tracks preserved on the RIS suggest recent evolution (i.e. last millennial) of the ice shelf. Ice cores collected from the recent Roosevelt Island Climate Evolution project are likely to provide a high-resolution record of atmospheric and ice-surface elevation changes during this time interval. These existing data along with the collection of data from two cruises to the Ross Sea will be used to reconstruct past ice shelf dynamics around Ross Bank to determine RIS future susceptibility and response of unpinning. This study of the Ross Bank will provide much needed ground truth for model prediction of cause and effect relationships associated with ice-shelf unpinning. Activities during two cruises to the Ross Sea include seismic surveying, multibeam, and Kasten and Jumbo Piston cores. In addition to the scientific broader impacts on ice sheet dynamics and sea level rise, this study provides the opportunity to train four graduate and four undergraduate students on geophysical- and geological-data acquisition, processing, sampling, interpretation and presentation. The LSU team will share the results with the public with local schools and the public; the project provides field experience for a Louisiana high-school science teacher.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.