Antarctic sediments trace repeated loss of the Amundsen ice sector
A reconstruction of past warm periods points to repeated extensive ice loss around Antarctica’s Thwaites and Pine Island glaciers. The peer-reviewed study links sediment changes to retreat in the Amundsen Sea sector over the last 800,000 years. Its findings inform understanding of ice-sheet sensitivity, while leaving the timing of future sea-level change unresolved.
Science··Evening
Warm periods left a recurring sediment signal
The Amundsen Sea sector drains ice from West Antarctica through glaciers including Thwaites and Pine Island. A peer-reviewed reconstruction identifies repeated extensive retreat there during warm intervals within the last 800,000 years. Mineral changes in offshore sediments suggest that delivery of material eroded beneath the ice largely stopped. The authors associate that interruption with ice losing contact with the seabed and withdrawing across substantial parts of the drainage basins.[1]
Ocean indicators accompany the retreat
The evidence combines clay minerals with microscopic fossils. Depletion of kaolinite, a mineral tracing particular rocks and older deposits, marked past changes in glacier-derived sediment supply. Other minerals were consistent with deep water arriving from farther north, while diatom fossils indicated warmer surface waters. The combination led the researchers to infer an ocean influence on retreat, rather than treating a single sediment component as a direct measurement of ice extent.[1]
The reconstructed sector holds substantial sea-level significance
Loss of the studied drainage sector corresponds to ice representing at least approximately 1.5 metres of global sea-level contribution. That figure describes the sector’s scale, rather than a forecast date. Sediment ages, transport processes and gaps in one core constrain the reconstruction. Ice could have persisted elsewhere in West Antarctica during these intervals; the result concerns the Amundsen sector rather than disappearance of the entire ice sheet.[1]
