Mélange‐Driven Coupling Between the Central Pine Island Ice Shelf and the Piglet Glacier Reverses Recent Acceleration Trends

Abstract By analyzing velocity changes of the Pine Island Ice Shelf (PIIS) from October 2014 to August 2025 using Sentinel‐1A/B imagery, we find that the PIIS flow changed markedly over this period. A distinct slowdown occurred at the central PIIS from 14 March 2022 to 20 January 2023, during which velocities decreased from 13.15 ± 0.04 to 12.71 ± 0.17 m day −1 (−0.44 ± 0.18 m day −1 yr −1 ). Piglet Glacier, a major tributary of the PIIS, also experienced two deceleration periods between 2023 and 2025. The transitions from acceleration to deceleration and then to near‐steady flow coincided with substantial changes in mélange configuration. Our analysis clearly demonstrates that the flow of the central PIIS and Piglet Glacier is highly sensitive to mechanical coupling along their shear margins. Specifically, the recent slowdowns in the ice flow are most easily explained by variations in the state and configuration of dense ice mélange.