Unpinning of the Ross Ice Shelf from Ross Bank

从罗斯浅滩解开罗斯冰架

• 批准号: 1841136
• 负责人: Philip Bart
• 金额: $ 74.58万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1841136&HistoricalAwards=false
• 关键词: Unpinning; Ross; Ice; Shelf; Bank

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.

当南极洲内部的冰川流出大陆边缘并延伸到海洋中时，南极冰架就形成了。这些冰架可以起到支撑作用，限制冰从大陆内部流向海洋。由此造成的支撑性冰的丧失可能会导致将冰输送到海洋的冰流加速，从而导致冰质量负平衡和全球海平面上升。因此，南极冰架减薄率高是一个主要问题。这些厚厚的冰架的范围通常由冰下地形高点或固定点控制，如离岸岛屿和/或海底堤岸，这往往会减缓内陆冰川的离岸排放。冰架脱离固定点可能会导致冰架快速后退，减少支撑。问题仍然存在，现代冰架如何与这些固定点脱钩，以及在冰架解锁后，离岸冰量将如何重新组织？该项目从罗斯海获取沉积物岩心和海底勘测数据，将用于生成罗斯冰架(RIS)如何以及何时从海底岸边解锁的详细重建图，以便了解西南极冰盖(WAIS)目前的稳定性，以及如果罗斯冰架从包括罗斯福岛在内的现有固定点分离，未来罗斯冰架可能发生破坏的可能性。研究调查了罗斯冰架(RIS)如何、为什么以及何时从罗斯滩解锁，以评估最近解锁事件中的冰盖和冰架行为。保存在RIS上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(即最近千年)的演化。从最近的罗斯福岛气候演变项目中收集的冰芯可能会提供这段时间内大气和冰面海拔变化的高分辨率记录。这些现有的数据以及从罗斯海的两次巡航收集的数据将用于重建罗斯浅滩周围过去的冰架动力学，以确定罗斯浅滩未来的敏感性和解锁反应。这项对罗斯滩的研究将为与冰架解锁相关的因果关系的模型预测提供急需的基础事实。在两次前往罗斯海的航行中，活动包括地震测量、多波束以及卡斯滕和巨型活塞芯。除了对冰盖动力学和海平面上升产生更广泛的科学影响外，这项研究还为4名研究生和4名本科生提供了关于地球物理和地质数据的获取、处理、采样、解释和介绍的培训机会。路易斯安那州立大学团队将与当地学校和公众分享成果；该项目为路易斯安那州的一名高中科学教师提供实地经验。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。