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

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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.