NSF-NERC: Melting at Thwaites Grounding Zone and its Control on Sea Level (THWAITES-MELT)

NSF-NERC：思韦茨接地区的融化及其对海平面的控制（THWAITES-MELT）

• 批准号: 1739003
• 负责人: David Holland
• 金额: $ 216.5万
• 依托单位: New York University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-04-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1739003&HistoricalAwards=false
• 关键词: NSF; NERC; Melting; Thwaites; Grounding

This project contributes to the joint initiative launched by the U.S. National Science Foundation (NSF) and the U.K. Natural Environment Research Council (NERC) to substantially improve decadal and longer-term projections of ice loss and sea-level rise originating from Thwaites Glacier in West Antarctica. The fate of the West Antarctic Ice Sheet (WAIS) is one of the largest uncertainties in projections of sea-level change. Thwaites Glacier (TG) is a primary contributor to sea-level rise and its flow is accelerating. This faster flow is a response to reduced buttressing from its thinning, floating ice shelf, and is ultimately caused by ocean-driven melting. The degree to which costly and geopolitically-challenging sea-level rise will occur therefore hangs to a large extent on ice-ocean interactions beneath such Antarctic ice shelves. However, the Thwaites system is not sufficiently well understood, exposing a significant gap in our understanding of WAIS retreat, its ocean-driven forcing, and the consequences for sea level. The chief regulators of TG's retreat are ice and ocean processes in its grounding zone, the location where the ice flowing from inland goes afloat. Ice and ocean processes at this precise locale are central to our understanding of sea-level rise, yet key variables have not been constrained by observation. Model projections of TG's future display extreme sensitivity to melting in the grounding zone and how that melting is applied. Equally-credible melt rates and grounding-zone glaciological treatments yield divergent trajectories for the future of West Antarctica, ranging from little change to large-scale ice sheet collapse with a half a meter or more of sea-level rise. The enormous uncertainty in outcome stems from the lack of observations in this critical grounding zone region. The enhanced understanding of melting of TG's ice shelf that will come from this project's focused observational program will be built into state-of-the-art coupled ice-sheet and ocean models. These physics-rich, high-resolution models will allow the potential sea-level contribution of TG to be bounded to an unprecedented degree.This project will enable global and regional climate modelers to make a substantial improvement to projections of future ocean conditions over the continental shelf by providing physics-based projections of TG's sea-level contribution. The team proposes a suite of integrated activities: (1) multi-year oceanographic time series from beneath TG's ice shelf to quantify melting processes that need inclusion in ocean models, with a strong focus on the grounding zone, (2) analogous measurements on the glacier to validate processes governing grounding-line retreat, (3) coupling of these in situ measurements with novel, high-resolution space-borne observations, (4) building this new understanding into state-of-the-art ocean (MIT General Circulation Model and Imperial College Ocean Model) and ice sheet (WAVI) models to correctly simulate the TG system, (5) coupling the models and running with realistic present-day ocean forcing to project the state of TG basin over the next hundred years. The international team will use a range of techniques, from the well-established, such as using a hot-water drill to instrument the ice column and water column in the grounding zone, through to the cutting-edge, such as deploying a borehole deployable remotely operated vehicle to survey the grounding zone, and using phase-coherent radar to monitor ice strain and basal melt rates. The outcome of the project will be a more complete understanding of the TG system in the critical zone extending from a few kilometers inland of the grounding line, through the grounding zone, and out under the ice shelf.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.

该项目有助于美国国家科学基金会（NSF）和英国自然环境研究委员会（NERC）发起的联合倡议，从而实质上改善了来自西南阿尔蒂卡的Thwaites Glacier的冰丢失和海平面上升的十年和长期预测。南极冰盖（WAIS）的命运是海平面变化预测中最大的不确定性之一。 Thwaites冰川（TG）是海平面上升的主要贡献者，其流动正在加速。这种更快的流程是对削减，漂浮的冰架减少支撑的反应，最终是由海洋驱动的熔化引起的。因此，在这种南极冰架下下方的冰山相互作用上，将在很大程度上悬挂着昂贵和地缘挑战的海平面上升程度。但是，THWAITS系统的理解还不够充分，在我们对Wais撤退，其海洋驱动强迫以及对海平面的后果方面的理解中占据了很大的差距。 TG撤退的主要监管机构是其接地区域中的冰和海洋过程，该地点是从内陆流出的冰块。在这个精确的地方，冰和海洋过程对于我们对海平面上升的理解至关重要，但是关键变量并未受到观察的限制。 TG的未来模型预测表现出对接地区域融化的极端敏感性以及如何应用熔化。同样有信心的熔体速率和接地区冰科处理为南极西部的未来产生不同的轨迹，范围从几乎没有变化到大规模的冰盖倒塌，海平面上升了半米或更多。结果的巨大不确定性源于该关键基础区域中缺乏观察结果。 对TG的冰架融化的增强理解将来自该项目的重点观察计划，将内置在最先进的耦合冰盖和海洋模型中。这些物理学丰富的高分辨率模型将使TG的潜在海平面贡献能够限制为前所未有的程度。该项目将使全球和地区气候建模者能够通过提供基于TG的海平面贡献的物理学预测来对大陆货架上未来海洋条件的预测进行实质性改善。 The team proposes a suite of integrated activities: (1) multi-year oceanographic time series from beneath TG's ice shelf to quantify melting processes that need inclusion in ocean models, with a strong focus on the grounding zone, (2) analogous measurements on the glacier to validate processes governing grounding-line retreat, (3) coupling of these in situ measurements with novel, high-resolution space-borne observations, (4)将这种新的理解建立在最先进的海洋（麻省理工学院通用循环模型和帝国大学海洋模型）和冰盖（WAVI）模型中，以正确模拟TG系统，（5）耦合模型并与现实的当今海洋一起运行，强迫未来百年来投射TG盆地。国际团队将使用一系列技术，从建立良好的技术（例如使用热水钻）来仪器在接地区中的冰柱和水柱到尖端到尖端，例如部署可钻孔的可远程操作的车辆来调查接地区，并使用相位相位的雷达来监视冰菌株和基础基础融合率。该项目的结果将是对关键区域中TG系统的更全面了解，该系统从地面内陆几公里，直到接地区域内，并在冰架下延伸。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识和更广泛影响的评估来评估Criteria通过评估的支持，并被认为是值得的。

项目成果

The Southern Ocean and its interaction with the Antarctic Ice Sheet

• DOI: 10.1126/science.aaz5491
• 发表时间: 2020-03-20
• 期刊: SCIENCE
• 影响因子: 56.9
• 作者: Holland, David M.;Nicholls, Keith W.;Basinski, Aurora
• 通讯作者: Basinski, Aurora

Rapid glacier retreat rates observed in West Antarctica

• DOI: 10.1038/s41561-021-00877-z
• 发表时间: 2022-01
• 期刊: Nature Geoscience
• 影响因子: 18.3
• 作者: P. Milillo;E. Rignot;P. Rizzoli;B. Scheuchl;J. Mouginot;J. Bueso-Bello;P. Prats-Iraola;L. Dini