Roughness of Ice Shelves Is Correlated With Basal Melt Rates. Issue 21 (1st November 2021)

• Record Type: Journal Article
• Authors: Watkins, Ray H.; Bassis, Jeremy N.; Thouless, M. D.
• Is Part Of: Geophysical research letters. Volume 48:Issue 21(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-11-01
• Subjects: ice shelf -- roughness; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL094743
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Ice shelf collapse could trigger widespread retreat of marine‐based portions of the Antarctic ice sheet. However, little is known about the processes that control the stability of ice shelves. Recent observations have revealed that ice shelves have topographic features that span a spectrum of wavelengths, including basal channels and crevasses. Here we use ground‐penetrating radar data to quantify patterns of roughness within and between ice shelves. We find that roughness follows a power law with the scaling exponent approximately constant between ice shelves. However, the level of roughness varies by nearly an order of magnitude between ice shelves. Critically, we find that roughness strongly correlates with basal melt, suggesting that increased melt not only leads to larger melt channels, but also to increased fracturing, rifting and decreased ice shelf stability. This hints that the mechanical stability of ice shelves may be more tightly controlled by ocean forcing than previously thought. Plain Language Summary: The future stability of the Antarctic ice sheet is linked to the stability of floating portions of the ice sheet called ice shelves. There has been recent speculation that the collapse of ice shelves could trigger an acceleration of the discharge of grounded ice, resulting in an accelerated sea level rise. Observations show that the topography of ice shelves is related to features, such as melt channels and crevasses, that are a direct result of melting and fracturing. Here we use ground‐penetrating data collected from various airborne survey campaigns to calculate roughness of seven ice shelves across Antarctica. We find that roughness varies considerably between ice shelves and that increased roughness strongly correlates with increased basal melt. This connection hints at a complex interplay between increased melt rates and roughening of ice shelves, and suggests that basal melt may trigger widespread fracturing, influencing the mechanical stability of ice shelves. Key Points: Ice shelves have bumps in their topography that correspond to crevasses, melt channels and other features We quantify the size of these bumps, called roughness, and find that the magnitude is spatially variable both between and within ice shelves Roughness of different ice shelves strongly correlates with the magnitude of basal melt