Abstract
Abstract. Submarine melting of the calving face of tidewater glaciers and the mechanical back force applied by the ice mélange layer are two mechanisms generally proposed to explain seasonal variations at the calving front of tidewater glaciers. However, the way these processes affect the calving rate and glacier dynamics remains uncertain. In this study, we used a finite element-based model that solves the full Stokes equations to simulate the impact of these forcings on two-dimensional theoretical flow line glacier configurations. The model, which includes calving processes, suggests that frontal melting affects the position of the terminus only slightly (less than a few hundred metres) and does not affect the multiannual glacier mass balance at all. However, the ice mélange has a greater impact on the advance and retreat cycles of the glacier front (more than several kilometres) and its consequences for the mass balance are not completely negligible, stressing the need for better characterization of forcing properties. We also show that ice mélange forcing against the calving face can mechanically prevent crevasse propagation at sea level and hence prevent calving. Results also reveal different behaviours in grounded and floating glaciers: in the case of a floating extension, the strongest forcings can disrupt the glacier equilibrium by modifying its buttressing and ice flux at the grounding line.
Highlights
In the context of global warming, the cryosphere’s contribution to sea level rise is a major concern
The Greenland Ice Sheet (GIS) mass loss, which was 142 ± 49 Gt a−1 on average over the past 2 decades, has increased in recent years to reach an estimated value of 263 ± 30 Gt a−1 between 2005 and 2010 (Schrama and Wouters, 2011; Shepherd et al, 2012) and 359.8 ± 28.9 Gt a−1 between April 2009 and 2012 (Khan et al, 2014). This mass loss extended over a large part of the GIS (Khan et al, 2010; Schrama and Wouters, 2011; Khan et al, 2014), which is becoming a major contributor to sea level rise (Cazenave, 2006; Rignot et al, 2011)
Ice mélange and melting of the glacier front have been reported by many authors to influence the behaviour of tidewater glaciers
Summary
In the context of global warming, the cryosphere’s contribution to sea level rise is a major concern. The Greenland Ice Sheet (GIS) mass loss, which was 142 ± 49 Gt a−1 on average over the past 2 decades, has increased in recent years to reach an estimated value of 263 ± 30 Gt a−1 between 2005 and 2010 (Schrama and Wouters, 2011; Shepherd et al, 2012) and 359.8 ± 28.9 Gt a−1 between April 2009 and 2012 (Khan et al, 2014) This mass loss extended over a large part of the GIS (Khan et al, 2010; Schrama and Wouters, 2011; Khan et al, 2014), which is becoming a major contributor to sea level rise (Cazenave, 2006; Rignot et al, 2011). Ice discharge is a significant mechanism, and the two related processes (melting and calving) directly affect the position of the front and affect the forces at the front; feedback between calving processes and ice dynamics are to be expected
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