IAP-25-131

Cracks in the ice: Disentangling the threats to Arctic ice shelves

Ice shelves fringe vast stretches of Arctic and Antarctic coastlines. By slowing the flow of ice-sheet outlet glaciers, ice shelves can reduce the rate of sea-level rise (SLR; Goldberg et al., 2009). Dauntingly, these natural barriers are on the front line of climate change, with their vulnerability to collapse intensified by warming environments and structural weakening. In this project, we will untangle the individual and compounding factors driving ice-shelf break-up through simulations using a cutting-edge glacier model informed by observations of the Milne Ice Shelf (MIS) of Ellesmere Island, Nunavut, Canada.

The MIS was the last intact ice shelf in the Canadian Arctic before it lost 43 % of its surface area through a calving event in July 2020 (Vincent and Mueller, 2020). The MIS is ideal for this project’s investigations given the wealth of observational data that exists for the site (e.g., Mortimer et al., 2012), the opportunity to further augment the morphological dataset through a field visit, and the numerous environmental and structural factors that may have contributed to the recent MIS failure. These factors include warming ocean and atmospheric temperatures that drive ice melt, thinning the ice shelf and leading to concentrated loading where meltwater pools (Banwell et al., 2019). Thinner shelves are more susceptible to flexure, this being amplified by longer exposure to unmodulated ocean waves as sea ice declines (Liang et al., 2024). Together, these processes increase ice-shelf strain, degrade ice integrity, and diminish an ice shelf’s resilience to failure.

Understanding the individual drivers of ice-shelf failure and how they interact is essential for accurately representing ice shelves in ice-sheet and Earth-system models used to predict future ice-sheet dynamics and SLR. This understanding and representation in large-scale models have been restricted by the complexity of the factors contributing to ice-shelf failure and their limited representation in process-based glacier models. However, recent advances in the Helsinki Discrete Element Model (HiDEM; Åström et al., 2013) create an opportunity for this project to substantially improve understanding of ice-shelf vulnerability to failure.

By leveraging these HiDEM developments and observational datasets, this project will provide unprecedented insights into the mechanisms driving ice-shelf collapse. This PhD programme will improve our understanding of ice shelves and enhance modelling capabilities to capture the factors driving their failure. Such contributions are critical for predicting the global impacts of changes in the polar cryosphere.

A background in physical geography, Earth science, or physics would benefit the student.

The morphological evolution (e.g., thickness change, ice damage) of the MIS and environmental factors (e.g., sea-ice and ocean conditions, atmospheric temperatures, winds) leading to and following the 2020 calving event will be investigated through an observational study using remote-sensing (i.e., optical and synthetic aperture radar satellite acquisitions) and field observations. The latter will include, if possible, new observations using, for example, ice-penetrating radar surveys and/or aerial photography collected by the student through a field campaign conducted in year 1. This visit is likely but conditional on our ability to join a collaborating team’s field expedition.

These data and analyses will inform the initialisation of HiDEM simulations, with the array of simulations designed to test the individual and compounding influences of factors such as thinning, damage, swell-induced flexure and melt ponding on the MIS’s break-up. Recent developments in the HiDEM code architecture allow for precise spatial mapping of ice characteristics (e.g., strength and integrity) and representation of flexure. The programme’s improved computational efficiency now allows for high-resolution simulations, facilitating the representation of important ice features (e.g., basal channels) and realistic magnitudes of thinning. In addition, an exciting development to merge ice- and fluid-modelling frameworks opens new doors to explore the role of melt ponding on ice-shelf failure. The student will be involved in developing and testing a new implementation of smoothed-particle hydrodynamics, used to represent fluid dynamics in melt ponds, within the discrete-element modelling framework.

Coupled with field and remote-sensing observations, these model developments will enable unprecedented investigations of ice-shelf failure. There is also an opportunity for the student to apply the advanced HiDEM capabilities to tests failure susceptibility of other ice shelves in the Arctic (e.g., the Ward Hunt Ice Shelf, Ellesmere Island) and Antarctic (e.g., George VI).

Year 1

Research design; Potential field work; Observational (field and remote-sensing) investigation; Writing literature review; Presentation at Stirling’s PhD symposium

Year 2

3D model domain initialisation; Simulations of thinning and exposure to ocean swell; Research / training visit with model developers in Finland; Presentation at Newcastle’s Physical Geography Seminar Series; Writing of first study chapter

Year 3

Simulations of melt ponding and ice damage; UK-based conference presentation; Publication of first study chapter; Writing of second study chapter

Year 3.5

Testing of model on Ward Hunt ice shelf; International conference presentation; Communication of results with end-users and collaborators; Publication of second study chapter; Writing of third study chapter and remaining sections of thesis

Based at the University of Stirling, the student will be integrated with expert support in remote sensing and glacier modelling offered in the ‘Earth and Planetary Observation Sciences’ and ‘Landscape and Environmental Change’ research groups. Further, concerted training and support with HiDEM will be provided by the model’s developers. Support in field data collection and analysis will be provided at Stirling, Newcastle, and through collaborations with Profs R. Bingham (University of Edinburgh, UK) and D. Mueller (Carleton University, Canada).

The student will present their work at local (e.g. The PhD Symposium of Stirling’s Division of Biological and Environmental Science (BES)), national (e.g. International Glaciological Society (IGS British Branch) and international conferences (e.g. European Geophysical Union’s General Assembly). They will gain experience in coding, the use of high-performance computing systems, field data collection, and Earth observation. Skills training (e.g. research design; thesis, article and grant writing; presentation skills) will be provided in-house at Stirling and Newcastle and through the broad range of trainings offered within the Iapetus DTP.