Contribution of Roughness to the Comprehension of Features on Ice Shelves and Implications for Ice Shelf Vulnerability

• Main Author: Watkins, Ray
• Other Authors: Bassis, Jeremy N, Thouless, Michael, Rood, Richard B, Lu, Wei
• Format: Thesis
• Language: English
• Published: 2023
• Subjects: Ice Shelves; Climate Change; Engineering (General); Engineering; Antarctic; Buttress; The Antarctic; Antarc*; Antarctica; Ice Sheet; Ice Shelf
• Online Access: https://hdl.handle.net/2027.42/177713; https://doi.org/10.7302/8170

Understanding the fate and stability of the Antarctic Ice Sheet is paramount for future projections of sea level rise in the coming centuries. Ice shelves---permanent, floating, sections of ice that fringe the coastline of Antarctica,---regulate the discharge of land-based ice into the ocean and are thought to buttress and stabilize the discharge of grounded ice upstream. Previous research has tied ice shelf collapse to the accelerated discharge of grounded ice into the ocean. However, our understanding of the processes that contribute to ice shelf weakening and demise remains underdeveloped. In this work, we aimed to improve our understanding of the processes that increase ice shelf vulnerability by developing a quantitative tool for measuring how fragmented an ice shelf is based on quantities that are increasingly available through remote sensing, such as ice thickness. We first explain how we can quantify the roughness of ice shelves and then calculate roughness of a series of ice shelves. We observe that consistent with previous studies, the roughness of ice shelves is largely determined by features associated with melting and fracturing of the ice. Basal melt carves out melt channels into the base of the ice shelf while fracture impart cracks (or crevasses) onto the ice shelf. We find that the topography of ice shelves is fractal, with the amplitude of roughness controlled by the melt rate. Next, we examine the discrete processes that are imparting roughness onto ice shelves and find that roughness is largest when basal melting and strain rate are largest. When both processes are active at the same time, the ice shelf becomes the roughest (or most fragmented). Finally, by using data obtained over the last two decades across a menagerie of ice shelves throughout Antarctica, we track how the roughness of ice shelves has changed over twenty years. Critically, we find that ice shelves have seen a statistically significant increase in roughness have also had a significant reduction in their overall size. This is ...