Basal Conditions on Rutford Ice Stream: Bed Access, Monitoring and Ice Sheet History

Lead Research Organisation: NERC British Antarctic Survey
Department Name: Physics

Abstract

The Antarctic and Greenland ice sheets play a major role in controlling Earth's sea level and climate, but our understanding of their history and motion is poor. At the moment, the biggest uncertainty in our ability to predict future sea level comes from these ice sheets. This is particularly important because sea level rise from ice sheets is increasing faster than expected, and because ice sheets have the potential to trigger irreversible sea level rise that would continue for many centuries. Reducing this uncertainty is currently one of the biggest challenges in glaciology. Our project aims to improve our understanding of two aspects of this uncertainty: first, the past behaviour of the West Antarctic Ice Sheet (WAIS), and second, the flow of the fast ice streams that drain it. By choosing the right location, we can address both these aims within one project. Rutford Ice Stream is one of the large, fast-flowing glaciers that drain WAIS and deliver the ice to the ocean. It has the advantage that a large amount of data have already been collected there from surface fieldwork, from aircraft, and from satellites. The next step is to access the ice stream bed directly, and the existing data mean we can identify the optimum locations for this. Using a hot-water drill we will make holes to the bed of the ice stream, through ice more than 2 km thick. Once the drill reaches the bed we will collect samples of sediment from beneath the ice. We will also collect sections of ice core from the ice column. Strings of instruments will be lowered down the holes to measure the pressure in the water system beneath the ice, the temperature profile in the ice and the way the ice deforms as it flows downstream. We will also insert probes into the bed that will measure how fast the ice is sliding, as well as the strength of the sediment in the bed itself. Borehole video cameras will record the nature of the ice, bed and water system, including how much sediment is frozen into the bottom of the ice. On the ice stream surface we will carry out a number of geophysical experiments designed to study the flow of the ice and to map the topography and the variations in basal water and sediment in the area around the drill holes. This will help us to interpret the measurements made in the drill holes. GPS receivers will track the motion of the ice surface; seismic surveys will map the softer and harder areas of bed sediment; radar surveys will show where water beneath the glacier is concentrated or distributed; and a seismometer array will detect the noise bursts emitted as the ice stream grinds over its bed. Project results will be analysed at the British Antarctic Survey, Swansea University and NERC-GEF. Other project partners at NASA-JPL, University College London and the University of Bristol will also contribute. When completed, the project will give information on: - An age for the most recent collapse of the ice sheet in this region - The water system beneath the ice - The thermal regime of the ice and bed - The partition of ice motion between the three different flow mechanisms - sliding, ice deformation and bed deformation The timing of the last ice sheet collapse will be extremely valuable because no other information yet exists in this region. It will help us to understand the way the ice sheet has changed as climate has warmed and cooled in the past. Our other results - characterising ice stream dynamics and how ice, water and the sedimentary bed interact - will help us understand the processes by which ice streams move, and how we should include these processes into models. The results will help to clarify previous work from ice streams elsewhere in Antarctica, which in some cases have been contradictory or inconclusive. Overall, these results will be big steps forward in our ability to understand the way ice sheets behaved in the past, what controls them today, and how they might evolve in the future.

Publications

10 25 50
 
Description New ice drill capable of reaching the bottom of the Antarctic Ice Sheet A new design of ice drill that can penetrate more than 2 km of ice has been developed and shipped to Antarctica. A bespoke, sledge-mounted drum, containing 2400 m of thermoplastic hose, was designed and built by the British Antarctic Survey and Able Engineering, a Kings Lynn engineering company. This new equipment will be used to drill to the bottom of Rutford Ice Stream, one of the huge, fast-moving glaciers that flow out of the Antarctic Ice Sheet. The drill was shipped to Antarctica on board the RRS Ernest Shackleton where it was successfully offloaded at remote location on the Ronne Ice Shelf. The subglacial environment is one of the least explored places left on Earth. When the drill reaches the bed of the ice stream, samples of the glacier bed will be collected and a series of instruments installed into the bed and within the ice. The results will tell us about any disintegration of the ice sheet in the past and about how the glacier is flowing in the present day. Up-to-date technology allowed compromises inherent in earlier designs to be overcome in the new drill. The first was being able to use a single, continuous length of hose; the second was the ability to drive the hose drum correctly using electric motors. The drill was designed to mount integrally onto a standard polar cargo sledge meaning, it can be moved around the ice sheet easily by tractor, despite its nearly 7 tonne weight. This will make it easy to redeploy to other sites elsewhere in Antarctica in the future.

March 2019. Field team have just returned from successfully drilling to the bed of a fast-flowing Antarctic glacier, three times, using the newly-developed deep hot-water drill. The ice is more than 2.1 km (nearly 1.5 miles) thick. These are the deepest subglacial access holes ever drilled using the hot-water technique. Results from the instruments installed in the holes are still very preliminary but, so far show that there is an active, high-pressure water system under the ice; the water pressure is so high that the ice is effectively "floating" on the bed, rather like an iceberg floats on the sea. We expect this will be a major factor in explaining why the ice is flowing so quickly.
Exploitation Route N/A at this stage
Sectors Environment

 
Description Collaboration with NASA-JPL ended 
Organisation National Aeronautics and Space Administration (NASA)
Department Jet Propulsion Laboratory
Country United States 
Sector Public 
PI Contribution The original BEAMISH Proposal included a collaboration with NASA-JPL in the US, specifically with Dr Alberto Behar, who was scheduled to take part in the BEAMISH fieldwork
Collaborator Contribution Dr Behar was scheduled to contribute borehole video equipment to the project
Impact N/A
Start Year 2013
 
Description New collaboration established with Penn State University, USA 
Organisation Penn State University
Department Department of Geosciences
Country United States 
Sector Academic/University 
PI Contribution Prof Sridhar Anandakrishnan will be incorporated into the field team.
Collaborator Contribution Penn State will contribute a large array of portable passive seismic recorders to the geophysical monitoring part of the data acquisition. Prof Anandakrishnan has successfully applied for funding from the US NSF to support his role in this collaboration.
Impact N/A
Start Year 2016
 
Description New collaboration established with University of California, Berkeley, USA 
Organisation University of California, Berkeley
Department Department of Physics
Country United States 
Sector Academic/University 
PI Contribution Proposed new borehole dust logging instrument will be deployed in the field to log the boreholes we drill through the ice stream.
Collaborator Contribution Dr Ryan Bay and his team will develop and build a new autonomous borehole dust logging instrument, suitable for operating in our BEAMISH Project boreholes, and provide it to the field campaign. A funding application has been submitted to the US NSF ("Dust-Bot: US-UK development of an autonomous dust logger") to fund this work.
Impact N/A
Start Year 2017
 
Title Down-hole optical and sonic logging tool 
Description A new logging tool was developed in-house to log hot-water drilled access holes in ice, either during the drilling process or after the drilling is completed. The tool includes downwards- and sideways-looking cameras (with light sources) to study the internal structure of the ice and the material at the bed; sonic transducers measure the borehole diameter and cross-section profile, with depth 
Type Of Technology Detection Devices 
Year Produced 2018 
Impact First successful deployments were completed during the main BEAMISH Project field campaign in January and February 2019. Further developments continue. 
 
Title Subglacial Plough 
Description An instrument to detect the physical strength of a sediment and the water pressure both at the ice-bed interface and at depths into the subglacial sediment is being developed and built. The instrument will be deployed via boreholes through >2km ice, beneath a fast-flowing glacier. 
Type Of Technology Detection Devices 
Year Produced 2018 
Impact Instrument is still under development. Once completed and deployed it will detect physical properties of the subglacial environment not easily detectable by other means, giving critical information on the mechanisms of fast glacier flow. The plough was deployed for the first time during the main BEAMISH Project field campaign in January and February 2019. It was installed permanently into the ice stream bed beneath 2.1 km of fast-moving ice. It is successfully transmitting data on basal hydrology and subglacial sediment properties to data loggers at the ice surface. 
 
Description Press release and subsequent media, and media-realted activities. 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Press release issued at a key stage in the fieldwork campaign (January 2019). Attracted considerable interest, both UK and internationally. High number of interviews (>10) and other activities (printed media, web-based activities et)c delivered, and still on-going (taken by >150 media outlets so far, as of March 2019).
Year(s) Of Engagement Activity 2019
URL https://www.bas.ac.uk/media-post/scientists-drill-to-record-depths-in-west-antarctica/
 
Description Twitter feed established and regularly updated for the BEAMISH Project's main fieldwork campaign 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Twitter feed from the Antarctic fieldwork (#hotwateronice) proved highly effective. Responses very positive. Currently has more than 1300 followers.
Year(s) Of Engagement Activity 2018,2019
URL https://twitter.com/hotwateronice?lang=en