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

格陵兰冰盖的冰流失导致海平面上升，预计在下个世纪还将继续。对未来冰川消融的预测依赖于模拟冰盖对气候变化的动态反应的模型。一个关键的挑战是基于过去几十年的观测来校准模型，部分原因是冰动力学在长时间尺度上根据气候变化进行调整。因此，过去的气候影响着现代国家。该项目将使用数值冰盖模型和长期气候数据来模拟格陵兰冰盖自1850年以来的变化，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，冰川融化与快速变暖并存，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。历史观察表明，如果有的话，这引发了格陵兰冰盖上许多冰川的消退，但它们正在进行的调整还没有得到彻底的调查。通过完全涵盖这一早期气候强迫时期的模拟，该项目将为最近的观测提供进一步的背景，并将提供有助于校准未来预测的模型的见解。该项目还将培训两名本科生。模型模拟将涵盖整个格陵兰冰盖，以及其几个主要出口冰川的案例研究。模拟将被迫使用跨越工业时代的气候再分析产品，从而能够现实地处理短期变化，包括20世纪20年代至30年代的快速变暖。主要的预期交付成果将是历史模拟，这些模拟捕捉了长期观察所建议的质量损失的主要阶段。模型输出将公开提供，以帮助更广泛的工作，以初始化格陵兰冰盖未来质量损失的模拟。另一项成果将是一组扰动的模拟，旨在澄清这个时代对冰川和冰盖演化的主要物理控制。这将包括评估气候多变性和地形边界条件的相对影响，以及二十世纪初气候强迫所造成的动态反应。总之，拟议的模型模拟将测试理论并量化早期强迫的影响，得出稀疏冰川与卫星时代之前的气候观测之间的新联系。这一奖项反映了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。

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.