2019-2020 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. 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. The project will utilize the Stampfli 2-Inch Drill and Winkie Drill to 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.

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. Thwaites and neighboring glaciers in the Amundsen Sea Embayment are rapidly losing mass in response to recent climate warming and related changes in ocean circulation. The processes driving the loss appear to be warmer ocean circulation and changes in the width and flow speed of the glacier, but a better understanding of these changes is needed to refine predictions of how the glacier will evolve. One highly sensitive process is the transitional flow of glacier ice from land onto the ocean to become a floating ice shelf. This flow of ice from grounded to floating is affected by changes in air temperature and snowfall at the surface; the speed and thickness of ice feeding it from upstream; and the ocean temperature, salinity, bathymetry, and currents that the ice flows into. The project team will gather new measurements of each of these local environmental conditions so that it can better predict how future changes in air, ocean, or the ice will affect the loss of ice to the ocean in this region.

The project will use a 400-meter winch with tower and sheave from the 4-Inch Drill as an instrument installation winch to lower instruments into hot water-drilled boreholes to measure ocean water properties at locations where warm Circumpolar Deep Water reaches the Thwaites grounding line.

Bubbles of ancient air trapped in ice cores have been used to directly reconstruct atmospheric composition, and its links to Antarctic and global climate, over the last 800,000 years. Previous field expeditions to the Allan Hills Blue Ice Area, Antarctica, have recovered ice cores that extend as far back as 2.7 million years, by far the oldest polar ice samples yet recovered. These ice cores extend direct observations of atmospheric carbon dioxide and methane concentrations and indirect records of Antarctic climate into a period of Earth's climate history that represents a plausible geologic analogue to future anthropogenic climate change. Through this project, the team will return to the Allan Hills Blue Ice Area to recover additional ice cores that date to 2 million years or older. The 4-Inch Drill and Blue Ice Drill will be used to recover the ice cores. The climate records developed from these ice cores will provide new insights into the chemical composition of the atmosphere and Antarctic climate during times of comparable or even greater warmth than the present day. Project results will help answer questions about issues associated with anthropogenic change including the relationship between temperature change and the mass balance of Antarctic ice and the relationship between atmospheric greenhouse gases and global climate change.

This project advances the growing field of winter limnology by using long-term data collected on northern lakes in Wisconsin in conjunction with a snow-removal experiment to look at under-ice algae and the implications for ice-loss on spring algae blooms. Using an IDDO Hand Auger, the researchers will collect lake ice cores through an ice thickness of up to one meter to study the biogeochemistry and habitat of lake ice.

The RAID drilling system will be put through a complete set of drilling trials, including augering firn, setting a borehole packer, drilling about 600 meters of grounded ice, and sampling of ice and rock at depth by wireline rotary coring. All components of the drilling system will be tested and evaluated. The 4-Inch Drill will be used to make 2-3 meters of smooth-walled borehole just below the firn-ice transition, at a depth of approximately 100 meters, to field test the setting of the borehole packer. The Intermediate Depth Logging Winch will be used to field test a borehole dust logger in the boreholes produced this season at Minna Bluff.

This project will utilize the Intermediate Depth Logging Winch to lower a series of optical+UV and radio sensor packages into the South Pole Ice Core (SPICEcore) borehole to the full depth of the hole (1751 m). The science goals include measurements of the radio absorption length of the ice from 100-1000MHz, radio birefringence in the ice, and ice index of refraction, all measured as a function of depth and ice temperature. The science team is interested in the optical scattering, absorption lengths, and luminescence as a function of depth and optical wavelength from the visible into the ultraviolet.