NSF-NERC: Disintegration of Marine Ice-sheets using Novel Optimised Simulations (DOMINOS)

该项目有助于美国国家科学基金会（NSF）和英国联合发起的联合倡议。自然环境研究理事会（NERC）将大幅改善对南极洲西部Thwaites冰川造成的冰损失和海平面上升的十年期和长期预测。 人们越来越多地认为，思韦茨冰川是不稳定的，容易崩溃。然而，对于质量损失率的预测存在很大的分歧，一些研究表明世纪到千年的规模撤退，而另一些则预测更具灾难性的解体。这些分歧意义重大，因为斯韦茨冰川和邻近冰川的迅速解体可能会引发或加速南极西部冰盖大部分地区的崩溃，从而影响未来几十年全球平均海平面上升。目前，由于缺乏可靠的冰断裂和脱离模型（称为冰山崩解）以及崩解和气候变化之间的相互作用，预测思韦茨冰川的冰损失率受到阻碍。这项研究解决了这一重大的知识差距，是出于需要改善对政策和规划至关重要的海平面预测。此外，科学家们对海平面上升预测的有用性的断言与利益攸关方对这项工作的可用性的看法之间也存在差距。该项目也是为了解决这一差距，通过确定可访问和可用的信息，以广泛的利益相关者社区，同时积极参与代表性不足的社区在附近的社区学院和学区，从事社区学院的学生在研究。 由于难以理解和预测控制冰盖稳定性的产犊和动态过程，预计西南极冰盖（特别是思韦茨冰川）的海平面上升速度具有很大的不确定性。 这种不确定性由于对裂冰过程、冰盖稳定性和气候之间的联系知之甚少而放大。为了解决这些不确定性，该项目旨在明确解决的过程中，可能会导致退缩和崩溃的思韦茨冰川使用一种新的冰动力学模型套件。 该模型套件包括一个离散元模型，能够模拟耦合断裂和冰流过程，三维全斯托克斯连续模型，和大陆尺度冰动力学模型（BISICLES）。冰动力学模型将与一套海洋作用力模型相结合，其中包括简单的卷流模型、中等复杂程度的2层海洋模型和全三维区域海洋模型。这种分层方法将使用高保真过程模型来通知和约束低阶模型的序列，这些模型是将改进的理解外推到更大尺度所需的，并有可能从根本上减少海洋冰盖崩溃和相关海平面上升速率的不确定性。大规模建模方法将在开源BISICLES冰动力学模型中进行测试和实施，并通过“产犊包”向其他研究人员公开提供。该奖项反映了NSF的法定使命，并被认为值得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来支持。

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. There is growing consensus that Thwaites Glacier is unstable and vulnerable to collapse. However, there is significant disagreement in projections of rates of mass loss, with some studies suggesting century to millennial scale retreat and others forecasting more catastrophic disintegration. These disagreements are significant because rapid disintegration of Thwaites and adjacent glaciers could potentially trigger or accelerate collapse of significant portions of the West Antarctic Ice Sheet with implications for global mean sea-level rise in the coming decades. Predicting rates of ice loss from Thwaites Glacier is currently hampered by a lack of reliable models of ice fracture and breakaway--called iceberg calving--and the interactions between calving and climate change. This study addresses this major knowledge gap, and is motivated by the need to improve sea-level projections critical for policy and planning. Moreover, there is also a gap between what scientists assert about the usefulness of sea-level rise predictions and stakeholder's perceptions of the usability of that work. This project is also geared to address this gap, by identifying the information that is accessible and usable to a broad community of stakeholders whilst proactively engaging with under-represented communities at nearby community colleges and school districts, engaging community college students in research. Projected rates of sea-level rise from the West Antarctic Ice Sheet (and Thwaites Glacier in particular) have large uncertainties due to difficulties in understanding and projecting the calving and dynamic processes that control the ice-sheet stability. This uncertainty is magnified by the poorly understood connection between calving processes, ice-sheet stability and climate. To address these uncertainties, this project seeks to explicitly resolve the processes that could cause retreat and collapse of Thwaites Glacier using a novel ice-dynamics model suite. This model suite includes a discrete element model capable of simulating coupled fracture and ice-flow processes, a 3D full Stokes continuum model, and the continental scale ice-dynamics model (BISICLES). Ice-dynamics models will be coupled to an ocean forcing model suite including simple plume models, intermediate complexity 2-layer ocean models and fully 3D regional ocean models. This hierarchical approach will use high-fidelity process models to inform and constrain the sequence of lower-order models needed to extrapolate improved understanding to larger scales and has the potential to radically reduce uncertainty of rates of marine ice-sheet collapse and associated sea-level rise. The large-scale modeling approach will be tested and implemented within the open source BISICLES ice dynamics model and made publicly available to other researchers via a "calving package".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.