USAP-DC

Current ice mass loss in Antarctica is largely driven by changes at glacier grounding lines, where inland ice transitions from being grounded to floating in the ocean. The rate and pattern of glacier retreat in these circumstances is thought to be controlled by the terrain under the ice. This project incorporates evidence of past ice-retreat events and other field data, such as grounding-line positions and dates, subglacial topography, and meltwater features, into numerical models of ice flow to investigate the influence that grounding-line processes and subglacial topography have on glacier retreat rates over the past 15,000 years. Recent observations suggest that Antarctic ice mass loss is largely driven by perturbations at or near the grounding line. However, the lack of information on subglacial and grounding-line environments causes large uncertainties in projections of mass loss and sea-level rise. This project will integrate geologic data from the deglaciated continental shelf into numerical models of varying complexity from one to three-dimensions. Rarely do numerical ice-sheet models of Antarctica have multiple constraints on dynamics over the past ~15,000 years (a period that spans the deglaciation of the Antarctic continental shelf since the Last Glacial Maximum). The geologic constraints include grounding-line positions, deglacial chronologies, and information on grounding line-ice shelf processes. The models will be used to investigate necessary perturbations and controls that meet the geological constraints. The multidisciplinary approach of merging geologic reconstructions of paleo-ice behavior with numerical models of ice response will allow the research team to test understanding of subglacial controls on grounding-line dynamics and assess the stability of modern grounding lines. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Person	Role
Simkins, Lauren	Investigator and contact
Stearns, Leigh	Investigator
Anderson, John	Co-Investigator
van der Veen, Cornelis	Co-Investigator

Antarctic Earth Sciences	Award # 1745055
Antarctic Glaciology	Award # 1745055
Antarctic Earth Sciences	Award # 1745043
Antarctic Glaciology	Award # 1745043

USAP-1745043_1

Data_Management.docx

Repository	Title (link)	Format(s)	Status
USAP-DC	Circum-Antarctic grounding-line sinuosity	GeoTIFF; Excel	exists
USAP-DC	Pennell Trough, Ross Sea bathymetry and glacial landforms	GeoTIFF; Excel	exists
USAP-DC	Elevation transects from Pine Island Bay	ZIP Archive	exists

1. Simkins, L. M., Greenwood, S. L., Munevar Garcia, S., Eareckson, E. A., Anderson, J. B., & Prothro, L. O. (2021). Topographic Controls on Channelized Meltwater in the Subglacial Environment. Geophysical Research Letters, 48(20). (doi:10.1029/2021gl094678)
2. Simkins, L. M., Stearns, L. A., & Riverman, K. L. (2021). Controls on circum-Antarctic grounding-line sinuosity. (doi:10.1002/essoar.10509090.1)
3. Munevar Garcia, S., Miller, L. E., Falcini, F. A. M., & Stearns, L. A. (2023). Characterizing bed roughness on the Antarctic continental margin. Journal of Glaciology, 1–12. (doi:10.1017/jog.2023.88)