2023-2024 Antarctic

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 objectives of the project are to learn whether basal conditions allow for rapid retreat of the Thwaites Glacier grounding line or whether retreat may re-stabilize near its current grounding line. These objectives will be achieved by using dedicated ice-flow modeling to guide targeted field surveys and experiments over two seasons, and to measure the most important unknown quantities and incorporate them into the models. Numerical models will be used to generate hypotheses for basal conditions that are testable through geophysical surveys and to project future behavior of Thwaites Glacier after assimilating the resulting data. The geophysical methods include seismic, radar, gravity, and electrical surveys that together will allow for a fuller characterization of the bed. The project will conduct field surveys in areas representative of different parts of the glacier, including across the margins, near the grounding line, and along the central axis of the glacier into its catchment. The Rapid Air Movement (RAM) Drill and Small Hot Water Drill will be used to create the shot holes required for the seismic measurements.

The transformation of snow into firn and then glacial ice is a fundamental process in glaciology. This project will introduce a new combination of firn datasets designed to lead to the development of next-generation, physics-based firn models. Advances in ice-core science and satellite altimetry demand firn models that can reliably simulate firn evolution in a range of climatic conditions, in a changing climate, and on long- and short-time scales. Current firn-compaction models are largely based on a steady-state assumption and tuned to particular geographical locations. Advancing beyond these models requires (1) measuring current firn-compaction rates (2) measuring grain-scale microstructures that play a crucial role in firn compaction, and (3) quantifying processes driving evolution of those microstructures. To decouple firn’s sensitivities to accumulation and temperature, the team will measure in situ strain rates by two independent methods and observe trends in microstructure in cores from sites spanning the accumulation gradient at Taylor Dome, while maintaining the same average temperature. The team will assess the ability of phase-sensitive radar to remotely measure firn-compaction rates, potentially simplifying future in situ measurements. This work will create a roadmap for collecting future microstructural data spanning key areas of temperature-accumulation space and simplify future collaborations through the availability of an open-source Community Firn Model.

Cores drilled through the Antarctic ice sheet provide a remarkable window on the evolution of Earth’s climate and unique samples of the ancient atmosphere. The clear link between greenhouse gases and climate revealed by ice cores underpins much of the scientific understanding of climate change. Unfortunately, the existing data do not extend far enough back in time to reveal key features of climates warmer than today. COLDEX, the Center for Oldest Ice Exploration, will solve this problem by exploring Antarctica for sites to collect the oldest possible record of past climate recorded in the ice sheet.

This component of COLDEX will recover a suite of shallow (16 x < 200 m) ice cores from the Allan Hills and other Antarctic Blue Ice Areas (BIAs) that contribute towards our understanding of how Earth's climate system operated during warmer periods in the past and why the periodicity of glacial cycles lengthened from 40,000 to 100,000 years approximately 1 million years ago. These ice cores will be dated using a newly developed array of dating methods to establish a preliminary depth/age time scale. Subsections of the cores will be imaged and analyzed for stratigraphic orientation using ECM and a suite paleoclimate properties (e.g. CO2, CH4, O2/N2/Ar, water isotopes, etc.).

This project will collect a novel dataset to determine how the West Antarctic Ice Sheet (WAIS) responded to a warmer climate during the last interglacial period (~125,000 years ago) by reconstructing the glacial history at the Mt. Waesche volcano in Marie Byrd Land, Antarctica. The researchers will use the Winkie Drill to drill through the ice sheet and recover bedrock that can be analyzed for its surface exposure history to help determine when the surface became overridden by the ice sheet. Reconstructing WAIS geometry when the ice sheet was smaller than present is difficult, and data are lacking because the evidence lies beneath the present ice sheet. The scientists will use the Winkie Drill to drill through the ice sheet and recover bedrock that can be analyzed for its surface exposure history to help determine when the surface became overridden by the ice sheet. The research will provide constraints on the past maximum and minimum spatial extent of WAIS during the last glacial-interglacial cycle.

Previous field expeditions to the Mt. Waesche volcano in Marie Byrd Land, Antarctica, used ground-penetrating radar to map the area's sub-ice topography and internal glacial layering. These radar profiles revealed discontinuities within the ice that represent lower ice levels that may have occurred in the past. This project aims to enhance the team’s rock core drilling program at Mount Waesche (see Constraining West Antarctic Ice Sheet Elevation during the last Interglacial) by dating the discontinuities in the ice. Using the Badger-Eclipse Drill, the team will collect ice cores from above and below the discontinuities to constrain the ages of the discontinuities. Isotopic and tephra analysis will be used to provide age constraints on the ice cores. These data will be correlated with other, well-dated West Antarctic ice cores to obtain a local chronology and date the discontinuities. This exploratory work aims to provide data that complement the results from subglacial rock cores to better constrain surface-elevation change, including both retreat and readvance, since the last interglacial.