USAP-DC

This project contributes to the joint initiative launched by the U.S. National Science Foundation (NSF) and the U.K. Natural Environment Research Council (NERC) to substantially improve decadal and longer-term projections of ice loss and sea-level rise originating from Thwaites Glacier in West Antarctica. The Thwaites Glacier system dominates the contribution to sea-level rise from Antarctica. Predicting how this system will evolve in coming decades, and thereby its likely contribution to sea level, requires detailed understanding of how it has responded to changes in climate and oceanographic conditions in the past. This project will provide a record of regional sea-level change by establishing chronologies for raised marine beaches as well as the timing and duration of periods of retreat of Thwaites Glacier during the past 10,000 years by sampling and dating bedrock presently covered by Thwaites Glacier via subglacial drilling. Together with climatic and oceanographic conditions from other records, these will provide boundary conditions for past-to-present model simulations as well as those used to predict future glacier changes under a range of climate scenarios. Specifically, the project will test the hypothesis--implied by existing geological evidence from the region--that present rapid retreat of the Thwaites Glacier system is reversible. The team aims to utilize two approaches: 1. To reconstruct relative sea level during the Holocene, it will map and date raised marine and shoreline deposits throughout Pine Island Bay. Chronological constraints on sea-level change will be provided by radiocarbon dating of organic material in landforms and sediments that are genetically related to past sea level, such as shell fragments, bones of marine fauna, and penguin guano. 2. To obtain geological evidence for past episodes of grounding-line retreat, the team will apply cosmogenic-nuclide exposure-dating of subglacial bedrock. Using drill systems recently developed for subglacial bedrock recovery, the team will obtain subglacial bedrock from sites where ice thickness is dynamically linked to grounding-line position in the Thwaites system (specifically in the Hudson Mountains, and near Mount Murphy). Observation of significant cosmogenic-nuclide concentrations--the team will primarily measure Beryllium-10 and in situ Carbon-14--in these samples would provide direct, unambiguous evidence for past episodes of thinning linked to grounding-line retreat as well as constraints on their timing and duration.

Person	Role
Goehring, Brent	Investigator
Hall, Brenda	Investigator
Campbell, Seth	Investigator
Venturelli, Ryan A	Investigator and contact
Balco, Gregory	Investigator

Antarctic Earth Sciences	Award # 2317097
Antarctic Glaciology	Award # 2317097
Antarctic Earth Sciences	Award # 1738989
Antarctic Glaciology	Award # 1738989

USAP-1738989_1

Deployment	Type
Mt. Murphy	field camp
NBP1902	ship expedition

None in the Database

Repository	Title (link)	Format(s)	Status
R2R	NBP1902 Expedition data	Not Provided	exists
USAP-DC	Pine Island Bay Relative Sea-Level Data	Excel	exists
ICE-D	Cosmogenic-Nuclide data at ICE-D	Not Provided	exists
USAP-DC	200 MHz ground-penetrating radar from Winkie Nunatak, West Antarctica	SEG-Y	exists
USAP-DC	In situ 14C data from a subglacial bedrock core near Pope and Thwaites glaciers	Excel	exists
USAP-DC	Firn and Ice Density at Winkie Nunatak	Microsoft Excel (OpenXML)	exists

1. Johnson, J. S., Venturelli, R. A., Balco, G., Allen, C. S., Braddock, S., Campbell, S., … Woodward, J. (2021). Review article: Existing and potential evidence for Holocene grounding-line retreat and readvance in Antarctica. The Cryosphere (doi:10.5194/tc-2021-360)
2. Balco, G., Brown, N., Nichols, K., Venturelli, R.A., Adams, J.R., Braddock, S., Campbell, S., Goehring, B., Johnson, J.S., Rood, D.H., Wilcken, K., Hall, B., Woodward, J. 2023. Reversible ice sheet thinning in the Amundsen Sea Embayment during the Late Holocene, The Cryosphere. First four authors contributed equally to this manuscript (doi:10.5194/tc-2022-172.)
3. Adams, J.R., Johnson, J.S., Roberts, S. J., Mason, P.J., Nichols, K.A., Venturelli, R.A., Wilcken, K., Balco, G., Goehring, B., Hall, B., Woodward, J., Rood, D.H. 2022. New 10Be exposure ages improve Holocene ice sheet thinning history near the grounding line of Pope Glacier, Antarctica, The Cryosphere. (doi:10.5194/tc-2022-82.)
4. Marschalek, J. W., Thomson, S. N., Hillenbrand, C.-D., Vermeesch, P., Siddoway, C., Carter, A., Nichols, K., Rood, D. H., Venturelli, R. A., Hammond, S. J., Wellner, J., & van de Flierdt, T. (2024). Geological insights from the newly discovered granite of Sif Island between Thwaites and Pine Island glaciers. Antarctic Science, 1–24. (doi:10.1017/s0954102023000287)
5. Braddock, S., Venturelli, R. A., Nichols, K., Moravec, E., Boeckmann, G. V., Campbell, S., Balco, G., Ackert, R., Small, D., Johnson, J. S., Dunbar, N., Woodward, J., Mukhopadhyay, S., & Goehring, B. (2024). Lessons learned from shallow subglacial bedrock drilling campaigns in Antarctica. Annals of Glaciology, 1–35. (doi:10.1017/aog.2024.12)