Collaborative Research: Glacier-sediment interactions during onset of tidewater glacier retreat

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。潮水冰川是流入海洋的冰川。虽然潮汐冰川只占世界上所有冰川的一小部分，但它们对气候很重要，因为它们含有大量的冰，而且它们可以迅速变化。我们预测未来海平面上升的能力取决于我们对这些冰川的了解程度。大多数潮汐冰川目前正在退缩。直到最近，阿拉斯加东南部的塔库冰川（Taku Glacier）是为数不多的正在前进的潮汐冰川之一。照片和卫星图像显示，冰川最近开始退缩，但不知道冰川会以多快的速度退缩。该项目将利用延时摄影、无人机调查、卫星数据和计算机模型来调查冰川退缩的早期阶段。该项目有望使人们更好地了解潮汐冰川退缩，并提高我们预测海平面上升的能力。该项目将支持早期职业研究人员和学生，他们也将参与冰川的实地课程。众所周知，潮汐冰川经历百年尺度的缓慢前进和十年尺度的快速后退的循环，这是由冰川-海洋界面发生的过程驱动的，包括冰山崩解、海底融化、沉积物沉积和侵蚀。这些循环可以在稳定的气候中发生，但气候可以改变前进和后退的时间尺度，也可以作为触发因素。由于前进阶段比后退阶段更长，在气候稳定的情况下，人们可以预期大多数潮汐冰川都在前进。目前的情况并非如此，因为世界上大多数潮汐冰川正在退缩或处于准稳定状态。直到最近，阿拉斯加东南部的塔库冰川是罕见的前进潮汐冰川之一。最近的观测表明，由于气候变暖，整个地区的冰川正在变薄，并开始从它在过去125年里形成和推进的终末冰碛上退缩。本项目将通过对Taku冰川的野外和遥感观测与数值模拟实验相结合，研究潮汐冰川向退缩转变的过程，以及在这一转变过程中冰川对气候敏感性的演变。通过加深对潮汐冰川稳定性的了解，该项目将改进对海平面上升的估计。该项目将支持一名博士后学者和本科生研究助理，该项目的实地工作将与在冰川终点举行的实地课程同时进行。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。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Tidewater glaciers are glaciers that flow into the ocean. Although tidewater glaciers make up a small percent of all the glaciers in the world, they are important for climate because they contain large volumes of ice and because they can change rapidly. Our ability to predict future sea level rise depends on how well we understand these glaciers. Most tidewater glaciers are currently retreating. Until recently, one of the few tidewater glaciers that was advancing was the Taku Glacier in Southeast Alaska. Photos and satellite imagery indicate that the glacier has recently started to retreat, but it is unknown how quickly the glacier will retreat. This project will investigate the early stages of the glacier’s retreat by using time-lapse photography, drone surveys, satellite data, and computer models. The project is expected to lead to a better understanding of tidewater glacier retreat and improve our ability to predict sea level rise. The project will support early career researchers and students, who will also be involved in a field course at the glacier. Tidewater glaciers are known to undergo cycles of slow, centennial-scale advance and rapid, decadal-scale retreat that are driven by processes occurring at the glacier-ocean interface, including iceberg calving, submarine melting, and sediment deposition and erosion. These cycles can occur in a steady climate, but climate can modify the timescales of advance and retreat as well as act as a trigger. Since the advance phase is longer than the retreat phase, in a steady climate one would expect the majority of tidewater glaciers to be advancing. This is not the case at present, as the majority of tidewater glaciers around the world are retreating or in a quasi-stable configuration. Until recently, Taku Glacier in Southeast Alaska was one of the rare advancing tidewater glaciers. Recent observations indicate that, due to a warming climate, the glacier is now thinning over its entire area and has begun to retreat off of the terminal moraine that it developed and prograded over the past 125 years. This project will investigate the processes by which a tidewater glacier transitions into retreat, and the evolving glacier sensitivity to climate during this transition, by integrating field and remote sensing observations of Taku Glacier with numerical modeling experiments. By advancing understanding of tidewater glacier stability, the project will lead to improved estimates of sea level rise. The project will support a postdoctoral scholar and undergraduate research assistants, and field work for this project will occur in parallel with a field course that will be held at the glacier terminus.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.