Antarctic ice front evolution, controlling factors, and projections: Six decades of satellite observations

Antarctic ice shelves exhibit diverse evolutionary behaviors over multi-decadal timescales, yet quantitative classification frameworks remain absent. We present the first continent-scale quantitative classification of ice shelf evolution using systematic analysis of 23 major ice shelves from 1963 to 2024. Four statistically distinct modes emerge, validated by PERMANOVA (F = 11.60, p < 0.001) and Monte Carlo stability analysis (94% classification robustness): Catastrophic Collapse (rapid, irreversible disintegration; Larsen A, B), Gradual Retreat (sustained area loss without recovery; Pine Island, Thwaites), Cyclic Recovery (advance-calving oscillations maintaining long-term stability; Ross, Ronne-Filchner, Amery), and Retreat-Dormant (initial retreat followed by multi-decadal quasi-stability; West, Shackleton). The RS-RC index framework quantitatively distinguishes modes based on retreat severity and recovery capacity, demonstrating that mode differentiation arises from systematic combinations of thermal forcing, geometric confinement, and catchment-ice flux balance rather than stochastic variability or shelf size alone. Factor prevalence analysis reveals clear discriminatory patterns: thermal forcing drives sustained retreat, while geometric confinement and large catchments enable cyclic recovery. Amundsen Sea ice shelves experience persistent retreat under CDW forcing independent of surface conditions, Antarctic Peninsula ice shelves exhibit bifurcated collapse versus gradual retreat behavior, and large embayment systems maintain multi-decadal stability through geometric confinement. Under forcing comparable to 1963-2024, conditional vulnerability assessment over the next 1-2 decades indicates large embayment ice shelves are expected to maintain cyclic patterns, while Amundsen Sea and western Peninsula ice shelves are likely to continue retreat.