Ice-Shelf Changes

Ice shelves provide important resistance to the outflow outlet glaciers and ice streams that drain the Antarctic Ice Sheet. This resistance, known as buttressing, can alter in response to changes in ice-shelf thickness. Over the last two decades, many ice shelves undergo significant thinning due to increased basal melting driven by warming oceans. The structural integrity of ice shelves has also weakened due to rift and crevasse formations. In West Antarctica, increased atmospheric warming in recent years also begins to produce large meltwater ponding and surface rivers on top of ice shelves, which, until several decades ago, are features that only commonly occur in the Arctic regions. With Antarctic ice shelves becoming more vulnerable to warming oceans and the atmosphere, it is crucial to understand the processes that control the ice-ocean-atmosphere interactions.

Our research uses multidecadal airborne radar sounding and satellite altimetry observations to assess the long-term stability of Antarctic ice shelves. This includes merging archival radar film data collected by SPRI-NSF-TUD in the 70s with modern digital-sounding data from NASA Operation IceBridge and ROSETTA-Ice. From these radar data, we can develop a long-term baseline to examine how basal melting, marine ice refreezing, ice shelf rifting, and crevasses have been changing along with recent ocean and atmospheric warming, as well as the formation of ice-shelf surface hydrology.

Collaborators: Matthew Siegfried (Colorado Mines), Dustin Schroeder (Stanford)
Current Students: Angelo Tarzona (EAS Ph.D.), Kierra Tran (EAS undergrad)

Selected Publications

  • Schroeder, D. M., Dowdeswell, J. A., Siegert, M.J., Bingham, R., Chu, W., MacKie, E. J., Siegfried, M.R., Vega, K.I., Emmons, J. R., & Winstein K. (2020) Multidecadal observations of the Antarctic ice sheet from restored analog radar records. Proceedings of the National Academy of Sciences. 116(38), 18867-18873.
  • Tinto, K. J., Padman, L., Siddoway, C.S., Springer, S.R., Fricker, H.A.,...Chu, W., et al. (2019) Ross Ice Shelf response to climate driven by the tectonic imprint on seafloor bathymetry. Nature Geoscience. 12, 441-449.
  • Bell, R.E., Chu, W., Kingslake, J., Das, I., Tedesco, M. & Tinto, K. J. et al. (2017) Antarctic ice shelf potentially stabilized by export of meltwater in surface river. Nature. 544(7650), 344-348.

Seawater Intrusion

The grounding zone is a critical region where the grounded glacier comes into contact with the ocean. At the grounding line, dense seawater can intrude beneath the subglacial freshwater discharge coming out of the glacier. The intrusion of this warm, salty ocean water under the grounded ice is proposed be one of the primary causes for glacier retreat in West Antarctica. Depending on how far the seawater intrusion can propagate inland, ocean-induced melting can result in order of magnitude and more uncertainty in the retreat rate of glaciers. Despite that, the process of seawater intrusion and its driving mechanism is still not well understood.

Theoretical modeling studies done by Alex Robel and others suggest that the subglacial hydrological properties and basal roughness at the grounding line could be important for controlling how far intrusion can extend inland. However, these parameters are not well constrained, and observations of these processes near the grounding line are extremely limited. We are currently developing a novel geophysical field approach focus on the joint application of ice-penetrating radar sounding and electromagnetics, and modeling methods to investigate the interaction between seawater intrusion and subglacial hydrology in Greenland.

This is an exciting new collaborative effort among our group, the Ice-Climate group led by Dr. Alex Robel , and the Electromagnetic group led by Dr. Samer Naif at EAS. The goal of this project is to develop joint-inversion methods using radar and EM and use them to inform new theoretical model development. Look out for more publications and conference presentations to come in the near future.

Collaborators: Alex Robel (GT EAS), Samer Naif (GT EAS)
Current Students: Ella Stewart (EAS undergrad)