Channelized topography amplifies melt-sensitivity of cold Antarctic ice shelves

The stability of Antarctic ice shelves, which regulate the flow of grounded ice into the ocean, depends critically on ocean-driven basal melting. Basal channels, widespread features beneath many ice shelves, focus thinning and reduce stability, yet their oceanic drivers remain poorly understood. Using high-resolution simulations of a cold-water ice shelf cavity, we show that interactions between circulation and channelized topography generate localized overturning that traps intruding warm Circumpolar Deep Water (CDW) beneath the ice, amplifying melt rates by an order of magnitude within channels. The resulting differential melting promotes channel growth and drives a fourfold increase in total basal mass loss, undermining the structural stability of the deeper part of the ice shelf. Our results reveal a key mechanism for basal channel evolution and indicate that even modest CDW intrusions could destabilize cold Antarctic ice shelves.