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

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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.