Glacier Calving in Greenland

Abstract

In combination, the breakaway of icebergs (calving) and submarine melting at marine-terminating glaciers account for between one third and one half of the mass annually discharged from the Greenland Ice Sheet into the ocean. These ice losses are increasing due to glacier acceleration and retreat, largely in response to increased heat flux from the oceans. Behaviour of Greenland's marine-terminating ('tidewater') glaciers is strongly influenced by fjord bathymetry, particularly the presence of 'pinning points' (narrow or shallow parts of fjords that encourage stability) and overdeepened basins (that encourage rapid retreat). Despite the importance of calving and submarine melting and significant advances in monitoring and understanding key processes, it is not yet possible to predict the tidewater glacier response to climatic and oceanic forcing with any confidence. The simple calving laws required for ice-sheet models do not adequately represent the complexity of calving processes. New detailed process models, however, are increasing our understanding of the key processes and are guiding the design of improved calving laws. There is thus some prospect of reaching the elusive goal of accurately predicting future tidewater glacier behaviour and associated rates of sea-level rise.

Projections of Future Sea Level Contributions from the Greenland and Antarctic Ice Sheets: Challenges Beyond Dynamical Ice Sheet Modeling

“…Such numerical schemes enable models to simulate the impact of ice front position on ice dynamics Bondzio et al, 2017). The physical processes driving calving, however, remain poorly understood, as discussed in a recent review of calving (Benn et al, 2017).…”

ISMIP6 Antarctica: a multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

“…Glaciol. ), calving(Benn et al, 2017) or interaction with Solid Earth(Gomez et al, 2015;Larour et al, 2019).The analysis of the simulations conducted here is presented relative to the ctrl_proj, and current trends in Antarctic mass loss are added afterwards. It was decided that using results of ice flow simulations directly, without subtracting the trend from 515 20 https://doi.org/10.5194/tc-2019-324 Preprint.…”

Comparison of four calving laws to model Greenland outlet glaciers

“…We implement and test four different calving laws, namely the height-above-buoyancy criterion (HAB, Vieli et al, 2001), the 30 crevasse-depth calving law (CD, Otero et al, 2010;Benn et al, 2017), the eigencalving law (EC, Levermann et al, 2012) and von Mises tensile stress calving law (VM, Morlighem et al, 2016), and model calving front migration of nine tidewater glaciers of Greenland for which we have a good description of the bed topography . The glaciers of this study are three branches of Upernavik Isstrøm (UI), Helheim glacier, three sectors of Hayes glacier, Kjer, and Sverdrup glaciers ( Fig.…”

“…In this study, we use two different estimations for the resistive stress, R. First, we use the stress only in the ice-flow direction to estimate R in which changes in direction are taken into account (Otero et al, 2010). The other estimation for R is the largest principal component of deviatoric stress tensor to account for tensile stress in any direction (Todd et al, 2018;Benn et al, 2017). We here use the term 'CD1' (flow direction) and 'CD2' (all directions), respectively, to refer to these two estimations for R.…”

“…It is therefore critical to further validate the stress threshold and improve this law by accounting for other modes of calving, or to develop new parameterizations. Current research based on 10 discrete element models (e.g, Benn et al, 2017) or on damage mechanics (Duddu et al, 2013) may help the community derive these new parameterizations.…”