Dynamic response of Antarctic Peninsula Ice Sheet to potential collapse of Larsen C and George VI ice shelves

Abstract

Abstract. Ice shelf break-up and disintegration events over the past 5 decades have led to speed-up, thinning, and retreat of upstream tributary glaciers and increases to rates of global sea-level rise. The southward progression of these episodes indicates a climatic cause and in turn suggests that the larger Larsen C and George VI ice shelves may undergo a similar collapse in the future. However, the extent to which removal of the Larsen C and George VI ice shelves will affect upstream tributary glaciers and add to global sea levels is unknown. Here we apply numerical ice-sheet models of varying complexity to show that the centennial sea-level commitment of Larsen C embayment glaciers following immediate shelf collapse is low (<2.5 mm to 2100, <4.2 mm to 2300). Despite its large size, Larsen C does not provide strong buttressing forces to upstream basins and its collapse does not result in large additional discharge from its tributary glaciers in any of our model scenarios. In contrast, the response of inland glaciers to a collapse of the George VI Ice Shelf may add up to 8 mm to global sea levels by 2100 and 22 mm by 2300 due in part to the mechanism of marine ice sheet instability. Our results demonstrate the varying and relative importance to sea level of the large Antarctic Peninsula ice shelves considered to present a risk of collapse.

Kinematic response of ice-rise divides to changes in ocean and atmosphere forcing

“…Velocity misfits obtained with these parameters are of similar magnitude to previous studies (e.g. Cornford et al, 2015;Schannwell et al, 2018).…”

The Effect of Foehn‐Induced Surface Melt on Firn Evolution Over the Northeast Antarctic Peninsula

“…Besides producing meltwater runoff on the grounded part of the NAP (Hock et al, ), surface melt can indirectly lead to ice loss through the process of ice shelf hydrofracture, whereby preexistent crevasses on floating ice shelves fill with accumulating meltwater, leading to the ice shelf disintegration and tributary glacier speedup and thinning (Glasser & Scambos, ; MacAyeal & Sergienko, ; Rott et al, , ; Scambos et al, , ; van der Veen, ; Vaughan & Doake, ; Weertman, ). The potential contribution to global sea level rise from tributary glaciers resulting from the removal of the Larsen C ice shelf (LCIS) has been estimated at <2.55 to 2,100 mm and <4.2 to 2,300 mm (Schannwell et al, ).…”

Topographic Shelf Waves Control Seasonal Melting Near Antarctic Ice Shelf Grounding Lines

“…More than 75% of Antarctic continental ice discharges through ice shelves (Bindschadler et al, ) that buttress the grounded ice (Dupont & Alley, ). A reduction in ice shelf buttressing may lead to grounded ice flow acceleration (Rack & Rott, ; Reese et al, ; Schannwell et al, ). Numerical ice sheet models suggest that ice shelf thinning due to melting from their contact with warmer ocean waters could destabilize the ice sheet (Favier et al, ; Schannwell et al, ), indicating a crucial dependence of the ice sheet on processes at the ice‐ocean interface.…”

“…A reduction in ice shelf buttressing may lead to grounded ice flow acceleration (Rack & Rott, ; Reese et al, ; Schannwell et al, ). Numerical ice sheet models suggest that ice shelf thinning due to melting from their contact with warmer ocean waters could destabilize the ice sheet (Favier et al, ; Schannwell et al, ), indicating a crucial dependence of the ice sheet on processes at the ice‐ocean interface. Here, we present new and highly resolving time series of melt rates observed on the Roi Baudouin Ice Shelf (RBIS), which is part of the belt of slowly melting (Rignot et al, ) smaller ice shelves situated over the narrow continental shelf along the coast of Dronning Maud Land, East Antarctica (Figure ).…”