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Abstract:
The Antarctic Ice Sheet is subject to amplifying feedbacks which can accelerate ice loss and lead to effectively irreversible retreat. We here analyse the distinct nature and risk of long-term ice loss for each individual drainage basin under different levels of warming. Depending on topographic and climatic conditions, we find that ice loss in some basins unfolds gradually with warming, whereas other basins are characterized by a critical threshold or tipping point beyond which large parts eventually disintegrate. A first threshold, potentially as low as 1–2 °C above pre-industrial levels, triggers the long-term collapse of ~40% of marine ice volume in West Antarctica. Marine-based sectors in East Antarctica, representing ~5 m of potential sea-level rise, are at risk of losing stability at 2–5 °C. Our results imply that the Antarctic Ice Sheet does not act as one single tipping element, but rather as several tipping systems interacting across drainage basins.
