Abstract:
Fracture is integral for understanding the health of grounded ice sheets and floating ice shelves, which are the world’s largest contributors to present-day and future sea level rise. However, how glacial ice fractures is one of the least understood processes in polar regions. Calving, or the fracture-driven separation of an iceberg from the larger ice sheet or shelf, represents about half of Antarctic ice shelf mass loss, while Greenland’s marine-terminating glaciers have had a ubiquitous acceleration of calving over the past four decades. In addition to calving, fractures can drain the hundreds to thousands of kilometers-wide lakes that form via melting on the Greenland Ice Sheet surface every summer, advecting meltwater and ice towards the ocean. For both calving and supraglacial lake englacial drainage events, we do not have theoretical models that can explain observations, causing biases in projections of our polar regions.

In this thesis, I develop physical models constrained by remote sensing observational data to describe fracture across these varied glacial environments. In Chapter 1, I consider the influence of the vertical temperature profile on fracture depths and ultimately calving stress across several fracture theories and two Antarctic ice shelves. In Chapter 2, I extend the most promising model from Chapter 1 from ice shelves to marine- and land-terminating glaciers with and without meltwater, finding analytical calving functions that could be utilized by numerical models. In Chapter 3, I combine remote sensing observations of supraglacial lake englacial drainage events with analytical theory to understand if cascading lake drainage events are consistent with predicted tensile stress perturbations. This body of work addresses pressing knowledge gaps in polar climate science by advancing our understanding of glacial ice fracture and its impacts.