Melt sensitivity of irreversible retreat of Pine Island Glacier

Melt sensitivity of irreversible retreat of Pine Island Glacier

. In recent decades, glaciers in the Amundsen Sea Embayment in West Antarctica have made the largest contribution to mass loss from the entire Antarctic Ice Sheet. Glacier retreat and acceleration have led to concerns about the stability of the region and the effects of future climate change. Coastal thinning and near-synchronous increases in ice flux across neighbouring glaciers suggest that ocean-driven melting is one of the main drivers of mass imbalance. However, the response of individual glaciers to changes in ocean conditions varies according to their local geometry. One of the largest and fastest flowing of these 5 glaciers, Pine Island Glacier (PIG), underwent a retreat from a subglacial ridge in the 1940s following a period of unusually warm conditions. Despite subsequent cooler periods, the glacier failed to recover back to the ridge and continued retreating to its present-day position. Here, we use the ice-flow model Úa to investigate the sensitivity of this retreat to changes in basal melting. We show that a short period of increased basal melt was sufficient to force the glacier from its stable position on the ridge and undergo an irreversible retreat to the next topographic high. Once high melting begins upstream of the ridge, 10 only near-zero melt rates can stop the retreat, indicating a possible hysteresis in the system. Our results suggest that unstable and irreversible responses to warm anomalies are possible, and can lead to substantial changes in ice flux over relatively short periods of only a few decades.

在南极西部的Amundsen Sea胚胎中，对整个南极冰期的质量损失最大的贡献，冰川恢复和加速使该地区的稳定性造成了最大的贡献，，，，冰川对海洋条件的变化的反应根据局部几何形状而变化。模型到研究这种撤退对基本熔化的敏感性。异常是可能的，并且可能在短短几十年的相对较短的时间内导致冰通量发生重大变化。