High Basal Melt Rates and High Strain Rates Lead to More Fractured Ice

• Published in: Journal of geophysical research. Earth surface 2024-04, Vol.129 (4), p.n/a
• Main Authors: Watkins, Ray H., Bassis, Jeremy N., Thouless, M. D., Luckman, Adrian
• Format: Article
• Language: English
• Subjects: Antarctic ice; Antarctic ice shelves; Antarctica; Antartica; Buttresses; Channels; Collapse; Crevasses; Deformation; Floating ice; Fracturing; geophysics; High strain rate; Ice; Ice calving; ice sheet; ice shelf; Ice shelves; Iceberg calving; Icebergs; Land ice; mellting; Melting; Oceans; Rifting; Roughening; roughness; Sea level; Sea level changes; Sea level rise; strain rate; Topography
• ISSN: 2169-9003; 2169-9011
• DOI: 10.1029/2023JF007366

Ice shelves limit the flux of grounded ice into the ocean by buttressing the discharge of land‐based ice upstream. Ice shelf weakening and collapse can lead to decreased buttressing and observations increasingly show that some ice shelves have experienced increased melt and increased calving, with recent hypotheses suggesting that increased melt leads to increased fracturing. However, the specific processes that control this correlation are not yet understood, with mechanisms other than melt affecting fracturing. Here we use the topography of the ice shelf base from BedMachine to investigate how basal melting and ice deformation contribute to crevasse and melt channel formation and evolution on the Pine Island Ice Shelf in West Antarctica. We find that high basal melt rates and high first principal strain rates lead to substantial roughening of the ice shelf through a collection of features, including melt channels and crevasses. Critically, melt channels and crevasses are the deepest in all directions at locations where the highest rates of melting and straining occur simultaneously. This suggests that the combination of melt rates and strain rates work in tandem to excavate and seed the deepest melt channels and crevasses on ice shelves. These features then may form lines of weakness that transform into rifts and, ultimately, the detachment boundary for calving events. This implies that melt and fracture play an important role in controlling the dynamics of ice shelves. Plain Language Summary Future sea level rise is tied to floating Antarctic ice shelves which limit the flow of ice from the continent. Ice shelf collapse could trigger an acceleration of land‐based ice into the ocean due to the loss of support, leading to future sea level rise. It has been shown that ice shelves with a higher melt have more crevasses, are more fractured, and are rough. However, the specific processes driving the potential connection between melt and fracture are not well understood. Here we use ice shelf topography to study the relationship between roughness and the size and spacing of geometric features on the Pine Island Ice Shelf. We find that high melt rates and high strain rates result in deeper and wider features on the ice shelf. We also find that, in contrast to the results of previous studies, both melt and fracture contribute to the deepest features. This suggests that these processes contribute to enhancing the depth of features. We hypothesize that this amplif