The Cryosphere, 21 April 2022

The large, very thick marine-terminating glaciers in the Arctic and Antarctic appear more vulnerable to rising temperatures than previously realized. These massive glaciers have sometimes sped up their discharge of ice into the ocean over the past few decades, beginning in the late 1990’s. This model study explains the mechanisms behind this ice loss by including the formation of meltwater ponds across the surface of such glaciers in response to higher atmospheric temperatures. Such ponds create large fractures in the ice, draining meltwater to the bottom of the glacier through crevasses. Meltwater trickles down through the cracks and lubricates the glacier’s downhill flow over bedrock, accelerating its movement toward the ocean. The basal lubrication creates a positive feedback loop that further destabilizes glaciers, with the strongest effect on large glaciers that are already slipping across the ground. This improved model for glacial movement can help identify glaciers in the Arctic and Antarctic that are most likely to rapidly slide downhill and break apart, discharging large icebergs into the ocean. The increased sensitivity and vulnerability of thick and fast-moving glaciers to climate change highlights the far-reaching consequences of rising temperatures; and the need for emissions reductions to curb ice loss and future sea-level rise.