Next-generation ice-sheet fracture models to quantitatively predict sea-level rise

Imperial College London
Civil and Environmental Engineering

Antarctic ice could provide a large contribution to sea-level rise, with an expected one metre rise by 2100 and potentially 15 metres by 2500 solely due to the disappearance of Antarctic ice. Ice-sheets deform over decades to centuries, slowly moving towards the ocean. Changes in the atmospheric and ocean temperatures cause the ice to melt, locally creating crevasses and smaller fractures over the years. Meltwater further accelerates the growth of these newly created fractures, eventually reaching a point where the outermost part of the ice-sheet is unable to support itself: The fracture suddenly propagates, causing an instantaneous loss of Antarctic ice.

This fracturing process is dominated and described through localised effects, requiring the fluid to be accurately captured within fractures that are characterised through its opening height of a few millimetres, while its origin (the lakes and crevasses that formed over years) and impact (sudden ice loss and the creation of icebergs) occur on much larger scales. These challenges have caused most researchers that simulate ice- sheet melting to use semi-empirical models, basing their predictions of future sea-level rise on historic data and thereby making the assumption that climate change merely speeds up the mass loss from Antarctic ice- sheets and glaciers, but does not significantly alter the underlying mechanisms.

My research proposes to use methods solely based on the underlying governing equations to describe this mass loss, overcoming the outlined challenges by using state-of-the-art models that remove the need to explicitly simulate the fluid within fractures, while still preserving their overall effects on the ice. This will be coupled to a novel time-discretisation scheme, allowing for both the suddenly created fractures and slow melting to be captured. Combining these approaches with modern methods to represent fractures will for the first time allow for large ice-sheets to be simulated, without having to resort to empirical relations. As a result, this fellowship will not only provide quantitative insight into iceberg creation and mass loss, referred to as the “holy grail” problem in glaciology, but also assess the accuracy of current projections and how they are influenced by changes in the environment.