Historical Simulations of Greenland Ice-sheet Dynamics: The Imprint of Early Ice Loss on Recent and Future Change

格陵兰冰盖的冰损失导致海平面上升，预计这种情况将持续到下个世纪。对未来冰损失的预估依赖于模拟冰盖对气候变化动态响应的模式。一个关键的挑战是根据过去几十年的观测来校准模型，部分原因是冰的动力学会随着长时间尺度的气候变化而调整。因此，过去的气候影响着现代国家。该项目将使用一个数值冰盖模型和长期气候数据来模拟1850年以来格陵兰冰盖的变化，特别关注冰盖对过去一个世纪气候的动态“记忆”。近几十年来，在快速变暖的同时，冰的损失得到了充分的记录，但在20世纪20年代至30年代，北极也出现了一段快速变暖的时期。现有的历史观测表明，这引发了格陵兰冰盖上许多冰川的退缩，但它们正在进行的调整尚未得到彻底的调查。由于模拟完全涵盖了这一时期的早期气候强迫，该项目将为最近的观测提供进一步的背景，并将提供有助于为未来预测校准模型的见解。该项目还将培养两名本科生。模型模拟将包括整个格陵兰冰盖，以及对其几个主要出口冰川的案例研究。在工业时代的气候再分析产品将强制进行模拟，使短期变化（包括20世纪20年代至30年代的快速变暖）能够得到现实的处理。主要的预期成果将是历史模拟，捕捉长期观测显示的质量损失的主要阶段。模型的结果将公开，以帮助更广泛的努力，初步模拟未来格陵兰冰盖的质量损失。另一项成果将是一组扰动模拟，旨在阐明这个时代冰川和冰盖演变的主要物理控制。这将包括评估气候变率和地形边界条件的相对影响，以及20世纪早期气候强迫所造成的动态响应。总之，提出的模式模拟将检验理论并量化早期强迫的影响，在稀疏的冰川和前卫星时代的气候观测之间建立新的联系。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。

Ice loss from the Greenland Ice Sheet contributes to sea level rise and is projected to continue over the next century. Projections of future ice loss rely on models that simulate the dynamic response of the ice sheet to climate changes. A key challenge is calibrating models based on observations made in the last few decades, in part because ice dynamics adjust to climate changes over long timescales. Past climate therefore affects the modern state. This project will use a numerical ice-sheet model and long-term climate data to simulate Greenland ice-sheet changes since 1850, with a specific focus on the ice-sheet’s dynamic “memory” of climate over the past century. Ice loss concurrent with rapid warming is well documented in recent decades, but a period of rapid Arctic warming also occurred in the 1920s-1930s. Historical observations, where available, suggest that this triggered the retreat of many glaciers on the Greenland Ice Sheet, but their ongoing adjustment has not been thoroughly investigated. With simulations that fully encompass this period of early climate forcing, this project will provide further context for recent observations, and will provide insights that will aid in calibrating models for future projections. This project will also train two undergraduate students.The model simulations will encompass both the Greenland Ice Sheet as a whole, as well as case studies on several of its major outlet glaciers. Simulations will be forced with climate reanalysis products that extend over the industrial era, enabling a realistic treatment of short-term variability, including the rapid warming of the 1920s-1930s. The primary intended deliverable will be historical simulations that capture the major phases of mass loss suggested by long-term observations. Model output will be made publicly available to aid broader efforts to initialize simulations of future mass loss of the Greenland Ice Sheet. An additional deliverable will be a set of perturbed simulations designed to clarify leading physical controls on the glacier and ice-sheet evolution over this era. This will include assessing the relative impacts of climate variability and topographic boundary conditions, and the dynamic response that was committed by early-twentieth-century climate forcing. Together, the proposed model simulations will test theory and quantify the effects of early forcing, drawing new links between sparse glacier and climate observations from the pre-satellite era.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.