Unpinning of the Ross Ice Shelf from Ross Bank

南极冰架是由来自南极洲内部的冰川流过大陆边缘并延伸到海洋中形成的。这些冰架可以起到支撑作用，限制冰从大陆内部流向海洋。由此造成的支撑冰的损失可能会导致冰流加速向海洋输送冰，造成负冰质量平衡和全球海平面上升。因此，南极冰架的高速率变薄是一个主要问题。这些厚冰架的范围通常由冰下地形高点或锚点控制，如近海岛屿和/或海底岸，它们往往会减缓内陆冰川冰的离岸排放。冰架从锚点上的脱离可能导致冰架迅速后退，减少支撑作用。问题仍然存在，现代冰架如何与这些固定点分离，以及在冰架分离后，离岸冰量的流动将如何重新组织？该项目从罗斯海获取沉积物岩心和海底调查数据，这些数据将用于详细重建罗斯冰架（RIS）是如何以及何时从海底银行分离出来的，以获得南极西部冰盖（WAIS）当前稳定性的视角，以及罗斯冰架如果从包括罗斯福岛在内的现有固定点分离出来，未来可能发生破坏的可能性。该研究调查了罗斯冰架（RIS）如何、为何以及何时从罗斯银行剥离，以评估最近一次剥离事件中冰盖和冰架的行为。在RIS上保存的流动条纹和裂谷轨迹表明，南极西部冰盖流动模式的变化表明冰架最近的演变（即最后一千年）。从最近的罗斯福岛气候演变项目收集的冰芯可能提供在这段时间间隔内大气和冰表面高度变化的高分辨率记录。这些现有数据以及两次前往罗斯海的游轮收集的数据将用于重建罗斯海沿岸过去的冰架动态，以确定RIS未来的敏感性和对剥离的响应。Ross Bank的这项研究将为与冰架剥离相关的因果关系的模型预测提供急需的基础真相。前往罗斯海的两次巡航活动包括地震测量、多波束、Kasten和Jumbo活塞岩心。除了对冰盖动力学和海平面上升的更广泛的科学影响外，本研究还为四名研究生和四名本科生提供了在地球物理和地质数据采集、处理、采样、解释和展示方面的培训机会。路易斯安那州立大学的研究小组将与当地学校和公众分享研究结果；该项目为路易斯安那州的一名高中科学教师提供了实地经验。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.