ABSTRACT

Bassis/1341568
This award supports the development of a model that can simulate both the flow and fracture of glacier ice, (including the slow creeping of that ice) as it spreads under its own weight all the way to the complete failure and detachment (calving) of icebergs from glaciers and ice shelves (floating expanses of glacier ice). Because iceberg calving accounts for nearly 50% of the mass lost from ice shelves, it plays an important role in the mass balance of glaciers and ice sheets, but remains a poorly understood process. Iceberg calving is also not yet accounted for in the current generation of continental-scale ice sheet models, which are used in state-of-the-art climate simulations and sea level rise projections, because simulating iceberg calving requires that we understand the initiation and propagation of fractures within the ice over timescales that can range from a few seconds to decades or even centuries. To address this problem, the primary objective of this project is to address this gap in our understanding by translating physical and computational approaches originally developed to simulate the fracture of quasi-brittle materials, like metals and concrete, to the fracture of glacier ice. Since it is both impossible and impractical to simulate the propagation of each individual crack in an ice sheet, we will seek a "continuum damage mechanics" approach that handles collections of cracks in a physically and thermodynamically consistent way to simulate failure at the large scale. This will be accomplished by using an approach that can simulate what happens to fractures after they form at the interface with the ocean.

This project seeks to advance our ability to predict the fate of the Greenland and Antarctic ice sheets and to quantify the ice sheet contribution to sea level rise in the coming centuries. Accomplishing this requires that we have a better understanding of why icebergs that can exceed the size of small New England States, detach and drift away from ice shelves. The broader impacts of the project also include graduate and undergraduate education through directed research projects and targeted engagement of under-represented minorities in low-income regions at the elementary and high school levels. Engagement with under-represented minorities will include counseling and planning for future career paths in the STEM fields and mentoring selected students during summer internship programs hosted by the University of Michigan, Vanderbilt University and Columbia University.

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