Collaborative Research: The demise of the world's largest piedmont glacier

马拉斯皮纳冰川位于阿拉斯加东南海岸，是世界上最大的山前冰川，是一种始于山脉并溢出到沿海平原的冰川。马拉斯皮纳冰川目前正在迅速变薄和后退，沿着底部边缘形成了一系列的冰川湖泊。其中一些湖泊与开阔的海洋之间只有一条狭窄的冰河沉积带相隔。冰川的底部远低于海平面，目前的所有迹象都表明，即使未来气候变化很小，退缩和变薄仍将继续，而且很可能会加速。这有可能是阿拉斯加在未来几十年内从一座冰川上失去的最大冰块。随着马拉斯皮纳冰川的消退和变薄，它将改变地貌，暴露出更多的岩石和冰雹，形成新的湖泊，和/或导致海岸线的重大变化，例如形成海洋峡湾。如果发生这种情况，这将是阿拉斯加和国家海岸线最大的现代变化之一，对陆地和海洋生态系统都有很大影响。这些变化也将构成国家公园系统近年来最大的一次陆地覆盖变化。这项工作的主要目标是使用计算机模型来估计马拉斯皮纳冰川及其周围地区的未来。实地收集的冰川上和冰川周围的测量结果将提供必要的模型输入数据。这项工作将产生一套关于冰川质量平衡、冰速度、冰厚度、冰床条件、地表碎屑范围和厚度、冰川湖泊发育和冰川热岩溶演化的综合数据集。这些数据将被纳入一个数字模型，该模型将用于探索马拉斯皮纳冰川演化的一系列未来可能情景。模型情景将考虑不同的气候轨迹以及模型参数的不确定性，例如与冰川底部的水文和运动有关的那些参数。具体来说，将讨论以下问题：1.从海洋到冰川前沿的路径对于灾难性的退缩是否至关重要？2.马拉斯皮纳的退缩是否会受到地表物质平衡的影响？3.模型预测的主要不确定性是什么？这项工作将有助于更好地理解气候变化如何与与气候无关的动态不稳定相互作用，在这个历史上一直以大冰川波动和时空变异性为特征的地区。虽然沿海冰川动态引起的退缩是常见的，但这些影响在持续变暖的情况下被放大。埃利亚斯国家公园，有潜力帮助人们想象气候变化对地球冰冻圈潜在的戏剧性影响。一位平面艺术家将把模型结果转换成醒目的视觉效果，展示一幅新风景的开阔。利用在线信息测试实验，该项目将测试和开发外联材料，以增加游客对正在进行的和预期的未来冰川变化和气候变化的了解。视觉和相关信息将成为互动展品，将在兰格尔-圣彼得堡吸引成千上万的参观者。埃利亚斯国家公园游客中心和在线。此外，该项目将在相关地球物理技术、现代冰盖建模方法和合作研究方面培训三名研究生。项目成果将在同行评议文献中发表，并在专业会议上公布。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。

Located on the coast of Southeast Alaska, Malaspina Glacier is the world’s largest piedmont glacier, a type of glacier that starts in the mountains and spills out onto the coastal plain. The Malaspina Glacier is currently rapidly thinning and retreating, forming a series of proglacial lakes along the bottom edge. Some of these lakes are only separated from the open ocean by a narrow band of sediment moraine. The underside of the glacier is located well below sea level and all current indications are that retreat and thinning will continue, and most likely accelerate, even with little future climate change. This has the potential to be the largest loss of ice in Alaska from one glacier in the next several decades. As the Malaspina Glacier retreats and thins it will transform the landscape, exposing more rocks and moraine, creating new lakes, and/or leading to significant changes in the coastline, such as the formation of marine fjords. If this happens, it will be one of the largest modern changes to Alaska’s and the nation’s coastline with large impacts to both terrestrial and marine ecosystems. These changes would also constitute the largest single change in terrestrial land cover in the National Park system in recent history.The main goal of this work is to use a computer model to estimate what the future could look like for the Malaspina Glacier and surrounding area. Measurements collected in the field, on and around the glacier, will provide the necessary model input data. The work will result in a comprehensive data set on glacier mass balance, ice velocity, ice thickness, glacier bed conditions, surface debris extent and thickness, proglacial lake development, and proglacial thermokarst evolution. These data will be ingested into a numerical model that will be used to explore a large range of possible future scenarios for the evolution of Malaspina Glacier. The model scenarios will account for different climate trajectories as well as uncertainties of model parameters, such as those associated with hydrology and motion at the underside of the glacier. Specifically, the following questions will be addressed:1. Is a pathway from the ocean to the glacier front critical for catastrophic retreat?2. Will the retreat of Malaspina be dominated by surface mass balance?3. What are the main uncertainties for model predictions?This work will lead to a better understanding of how climate change interacts with dynamic instabilities that are independent of climate, in an area that has historically been characterized by large glacier fluctuations and spatial and temporal variability. While dynamically caused retreats are common for coastal glaciers, these effects are amplified in the presence of ongoing warming.Malaspina Glacier is located in the Wrangell-St. Elias National Park and has the potential to help people envision the potentially dramatic effects of climate change on the Earth’s cryosphere. A graphic artist will convert the model results into striking visuals that show the opening up of a new landscape. Using an online message testing experiment, the project will test and develop outreach materials to increase visitor knowledge of ongoing and anticipated future glacier change and climate change. Visuals and associated information will become interactive exhibits that will engage thousands of visitors at the Wrangell-St. Elias National Park visitor center and online. In addition, this project will train three graduate students in relevant geophysical techniques, modern ice sheet modeling approaches, and collaborative research. The project outcomes will be published in peer-reviewed literature and presented at professional meetings.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.