Channels Along Base of Antarctic Ice Shelves Increase Melting

Nature Communications, 7 May 2026

Relatively small and brief intrusions of warm water beneath Antarctic ice shelves can significantly increase melting by leaving long grooves on their underside, known as basal channels, leading to rapid melt from below. When slightly warmer Circumpolar Deep Water surrounding the continent flows into an otherwise cold ice shelf cavity, it can become trapped within these narrow channels. Once confined, the warm water drives much faster melting along the channel walls and base. This focused melting can deepen the channels over time, weakening parts of the ice shelf that are especially important for slowing the flow of land ice into the ocean. The effect is strongest where deeper channels guide circulation, allowing warm water to remain in contact with the ice for longer periods compared to flat ice shelves. Ice sheet models that do not include these small-scale features can substantially underestimate melting and misrepresent where thinning occurs. This suggests that basal channels play a critical role in controlling how sensitive Antarctic ice shelves are to ocean warming, indicating greater potential instability of ice shelves and the ice sheet that is partially held in place by those ice shelves; and therefore future rates of sea-level rise.

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