TY - JOUR

T1 - Melt sensitivity of irreversible retreat of Pine Island Glacier

AU - Reed, Brad

AU - Green, Mattias

AU - Jenkins, Adrian

AU - Gudmundsson, Hilmar

PY - 2024/10/7

Y1 - 2024/10/7

N2 - In recent decades, glaciers in the Amundsen SeaEmbayment in West Antarctica have made the largest con-tribution to mass loss from the entire Antarctic Ice Sheet.Glacier retreat and acceleration have led to concerns aboutthe stability of the region and the effects of future climatechange. Coastal thinning and near-synchronous increases inice 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 inocean conditions varies according to their local geometry.One of the largest and fastest-flowing of these glaciers, PineIsland Glacier (PIG), underwent a retreat from a subglacialridge in the 1940s following a period of unusually warm con-ditions. Despite subsequent cooler periods, the glacier failedto recover back to the ridge and continued retreating to itspresent-day position. Here, we use the ice-flow model Úa toinvestigate the sensitivity of this retreat to changes in basalmelting. We show that a short period of increased basal meltwas sufficient to force the glacier from its stable position onthe ridge and undergo an irreversible retreat to the next to-pographic high. Once high melting begins upstream of theridge, only near-zero melt rates can stop the retreat, indicat-ing a possible hysteresis in the system. Our results suggestthat unstable and irreversible responses to warm anomaliesare possible and can lead to substantial changes in ice fluxover relatively short periods of only a few decades

AB - In recent decades, glaciers in the Amundsen SeaEmbayment in West Antarctica have made the largest con-tribution to mass loss from the entire Antarctic Ice Sheet.Glacier retreat and acceleration have led to concerns aboutthe stability of the region and the effects of future climatechange. Coastal thinning and near-synchronous increases inice 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 inocean conditions varies according to their local geometry.One of the largest and fastest-flowing of these glaciers, PineIsland Glacier (PIG), underwent a retreat from a subglacialridge in the 1940s following a period of unusually warm con-ditions. Despite subsequent cooler periods, the glacier failedto recover back to the ridge and continued retreating to itspresent-day position. Here, we use the ice-flow model Úa toinvestigate the sensitivity of this retreat to changes in basalmelting. We show that a short period of increased basal meltwas sufficient to force the glacier from its stable position onthe ridge and undergo an irreversible retreat to the next to-pographic high. Once high melting begins upstream of theridge, only near-zero melt rates can stop the retreat, indicat-ing a possible hysteresis in the system. Our results suggestthat unstable and irreversible responses to warm anomaliesare possible and can lead to substantial changes in ice fluxover relatively short periods of only a few decades

U2 - 10.5194/tc-18-4567-2024

DO - 10.5194/tc-18-4567-2024

M3 - Article

VL - 18

SP - 4567

EP - 4587

JO - Cryosphere

JF - Cryosphere

SN - 1994-0416

ER -