Fast-flowing ice: from the geological past to models of the future
This project will improve how we model the flow of ice sheets in the past and the future using geological data, ultimately providing more confidence in future sea level projections.
The potential collapse of parts of the Greenland and Antarctic ice sheets would lead to several meters of sea level rise in the coming centuries, posing a huge threat to homes and coastal infrastructure worldwide. A major source of uncertainty in projections of sea level rise is how ice streams —channels of fast-flowing ice— will evolve in the future. The numerical ice sheet models used in sea-level projections are typically overtuned to reproduce today’s ice velocity measured by satellites. Yet, ice flow mechanisms may significantly change in the future as ice sheets melt and retreat. Thus to make meaningful projections of ice flow in the future, we need to test and calibrate our models to periods when ice sheets were significantly different from today. Unfortunately, satellites’ fantastic ice velocity data only goes back a couple of decades, too short a time scale on which to observe widespread change, even if significant ice flow acceleration has been observed in some regions.
During the last ice age, ice sheets experienced significant and sometimes rapid widespread changes relevant to the future. Thankfully ice that once covered large parts of Northern Europe and Canada left traces of its flow in the landscape, enabling us to reconstruct the position of past ice streams (Stokes et al., 2016). The last deglaciation, 21 to 7 thousand years ago, provides the best record of how ice sheets flow and retreat under global warming conditions as the Earth experience the collapse of the North American and Eurasian ice sheets.
In this project, you will use the BISICLES numerical ice sheet model to simulate ice streams during the last deglaciation and the future evolution of the Greenland and Antarctic ice sheet. What makes BISICLES stand out from other complex ice sheet models is its ability to increase its resolution where and when it is needed (Figure 2). This allows us to efficiently and accurately simulate important mechanisms of ice sheet instability including the spontaneous generation of ice streams and has been applied in both contemporary and last ice age contexts. Most relevant to this project is its successful simulation of the flow of the British and Irish Ice sheet at the Last Glacial Maximum (LGM).
The project aims to use reconstructions of past ice streams to test and improve the simulation of ice flow in complex ice sheet models.
Objectives:
- Simulate ice flow at the last glacial maximum, the last deglaciation that followed, the present and the future with BISICLES. This would include the North American, Greenland and/or Eurasian and Antarctic ice sheets, depending on the candidate’s interests.
- Evaluate our ability to simulate the position, direction and width of past ice streams against geological records.
- Test different schemes for representing basal sliding and ice flow. There is potential to gain experience in model development.
- Run ensembles of simulations to evaluate the optimum values of uncertain parameters under past and present conditions.
Research questions:
- Can state-of-the-art ice sheet models simulate ice streams of the Last Glacial maximum?
- What processes are critical for adequately simulating ice streams and how they evolve under a warming climate?
- Can the geological records of past ice streams constrain projections of future ice sheet evolution?
This project is designed to have the flexibility to adapt to the researcher’s background, interests, strengths and future aspirations. For example, the successful candidate may choose to focus the efforts on ice sheet physics, model development, uncertainty quantification, comparison to glacial landforms or future projections.
Potential for high impact
This project has the potential to correct errors in current simulations of past and future ice sheet evolution and improve our confidence in projections of future sea level. The student will develop a highly sought-after, multidisciplinary skill-set, contributing towards the development of an interdisciplinary field of research that is at the forefront of glaciology. By the nature of this work, and due to its timeliness, there is strong potential for the PhD candidate to influence the direction of international research being carried out on this theme, and to thus establish a world-renowned reputation for innovative science.
Training
This interdisciplinary project will provide the successful PhD candidate with highly valued and sought-after skills in numerical ice sheet modelling and broad knowledge of ice sheet and sea level processes. This will equip the student with the necessary expertise to become a next-generation glaciologist, ready to carry out their own programme of innovative scientific research.
The student will benefit from working within the dynamic and multidisciplinary Physical Climate Change research groups and collaborating with international experts in ice sheets and sea level rise from the Centre for Polar Observation and Modelling (CPOM). There will be opportunities to present results at major, international conferences, e.g. AGU (San Francisco), EGU (Vienna) and attend residential summer schools (e.g. in Italy, USA, UK) and in-house workshops and courses.
Entry requirements
A good first degree (1 or high 2i), or a good Masters degree in a physical, mathematical or geophysical discipline, such as mathematics, physics, geophysics, engineering, environmental sciences or meteorology. Experience in programming (eg. Python, C++ …) or numerical modelling and/or some knowledge of glaciology is desirable.