Lead Supervisor: Neil Arnold, Scott Polar Research Institute
Co-Supervisors: Kelly Hogan, British Antarctic Survey & Rob Larter, British Antarctic Survey
Brief summary:
This project will use marine geophysical data from periods of deglaciation and numerical modelling to increase understanding of the impact of basal water and sediments on ice sheet flow, which are vital in understanding possible future ice sheet responses to climate change.
Importance of the area of research concerned:
Today we are witnessing decay of ice sheets on Greenland and West Antarctica at rates unprecedented outside major climatic transitions. Water and sediment at ice sheet beds play a critical role in processes that control ice flow, yet these environments are very difficult to access. Incorporation of these processes into numerical models of ice sheets is at an early stage, limiting our understanding of the role they play in deglaciation.
However, a vital record of subglacial water flow has been left in the glacial landforms and sedimentary successions produced by the decay of former ice sheets. Such data provide a clear path to address this issue by using the rich landform record to constrain ice-sheet models, and to directly simulate the conditions under which the landforms developed. Huge channels carved into former ice-sheet beds in Pleistocene North Sea sediments and over bedrock areas around Antarctica, as well as smaller subglacial channels that filled with sediment (eskers) as past ice sheets decayed are found across Northern Hemisphere high latitudes; these landforms provide amazing examples with which to constrain and model water flow beneath decaying ice sheets.
Project summary :
Interactions of ice sheets with sediment and water at their beds is a critical control on ice flow, yet such processes are difficult to observe under present-day ice sheets. Subglacial water flow and ice behaviour is archived in the geological record as glacial landforms and sedimentary facies that identify past basal conditions and ice behaviour. This project will focus on using and developing current numerical models to develop understanding of processes which form landforms associated with past water flow beneath ice sheets, from the erosion of major bedrock channels into the bed to the infilling of small channels incised up into the ice. The project will use constraints from the geological record to design new model experiments and will evaluate the climatic and glaciological conditions needed to form these features and, ultimately, explore their possible impact on ice dynamics.
What will the student do?:
The student will identify a suite of suitable landform case studies from the Northern Hemisphere and Antarctica and make measurements of the landforms and gather additional datasets (e.g., reconstructed climate, bed composition) with which to design novel model experiments to explore their formation. These may range from process-based models to simulate erosion of the bed and filling of channels to form eskers, with realistic climatic forcing and bed conditions, through to potentially building such physics into current large-scale ice sheet models. The project will utilise and adapt existing models (at landform through to and ice sheet scales) and constrain them using measured geomorphic and sedimentary information from glacial landforms. This combined approach of numerical modelling, well-constrained by geological observations, will firmly establish the ice sheet and climatic conditions necessary to produce what we have observed in the geological record from times of rapid deglaciation, and will provide new insights into what may happen to Greenland and Antarctica in the future as the climate warms, increasing meltwater availability.
References - references should provide further reading about the project:
Kirkham, J.D., Hogan, K.A., Larter, R.D., Arnold, N.S. and 8 others. Tunnel valley formation beneath deglaciating mid-latitude ice sheets: Observations and modelling. Quaternary Science Reviews (In Press). [will need updating]
Stevens, D. and 5 others. 2022. Effects of basal topography and ice-sheet surface slope in a subglacial glaciofluvial deposition model. Journal of Glaciology First View, pp1-13. https://doi.org/10.1017/jog.2022.71
Hewitt I.J. and Creyts, T.T. (2019) A model for the formation of eskers. Geophysical Research Letters 46(12), 6673–6680. https://doi.org/10.1029/2019GL082304
Applying
You can find out about applying for this project on the Scott Polar Research Institute page.
Dr Neil Arnold