Abstract
AbstractThe Antarctic Ice Sheet loses mass via its ice shelves predominantly through two processes: basal melting and iceberg calving. Iceberg calving is episodic and infrequent, and not well parameterized in ice-sheet models. Here, we investigate the impact of hydrostatic forces on calving. We develop two-dimensional elastic and viscous numerical frameworks to model the ‘footloose’ calving mechanism. This mechanism is triggered by submerged ice protrusions at the ice front, which induce unbalanced buoyancy forces that can lead to fracturing. We compare the results to identify the different roles that viscous and elastic deformations play in setting the rate and magnitude of calving events. Our results show that, although the bending stresses in both frameworks share some characteristics, their differences have important implications for modeling the calving process. In particular, the elastic model predicts that maximum stresses arise farther from the ice front than in the viscous model, leading to larger calving events. We also find that the elastic model would likely lead to more frequent events than the viscous one. Our work provides a theoretical framework for the development of a better understanding of the physical processes that govern glacier and ice-shelf calving cycles.
Highlights
The loss of ice from Antarctica is one of the main contributors to global sea-level rise (Church and White, 2011)
While the effective principal stress (EPS) is probably most useful to predict if a stress will trigger a calving event or not, some of our results are presented in term of deviatoric stress (τ) to facilitate the comparison between the 2-D models and the 1-D elastic beam model
Motivated by the importance of iceberg calving in ice-sheet mass loss, and by the persistent challenge of finding calving models that reliably forecast the evolution of ice sheets, we have examined the differences between viscous and elastic deformations at the hand of a particular calving process: the footloose mechanism, which is triggered by the formation of an underwater foot at the ice front
Summary
The loss of ice from Antarctica is one of the main contributors to global sea-level rise (Church and White, 2011). On a continent-wide scale, these two processes are estimated to account for approximately the same amount of mass loss, with the relative influence of each process varying across different ice-shelf systems (Rignot and others, 2013). Both processes have far-reaching effects, since the associated release of cold and fresh meltwater affects the water column and sea-ice formation Hellmer, 2004), both near the ice sheets and farther afield due to offshore transport by icebergs (Bigg, 2015) Depending on where they occur, both basal melting and iceberg calving could have implications for the stability of large parts of the ice sheet (e.g. Fürst and others, 2016; Reese and others, 2018)
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