West Antarctic Ice Sheet advance since the early Pliocene.
basic_science · Level V
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- Record sourced from PubMed, PMID 42251029.
- Also identified by DOI 10.1038/s41467-026-74100-1.
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Abstract
Current understanding of past ice dynamics in the Amundsen Sea-the most vulnerable part of the West Antarctic ice sheet (WAIS)-remains incomplete, hampering future predictions. Here, sediments from International Ocean Discovery Program Site U1532 on the continental rise reveal that ice-sheet dynamics strongly influenced detrital magnetic minerals supply. Minimal magnetite concentration during ~4.1-3.8 Ma reflects the smallest WAIS extent in the Amundsen Sea sector since ~4.33 Ma. Since ~4.1 Ma, WAIS expansion was closely linked to long-term global cooling. After ~3.2 Ma, elevated fine-grained magnetite indicates a sustained increase in sediment contribution from the Thwaites Glacier catchment. The abrupt ice-sheet expansion at ~3.2 Ma may reflect the crossing of a climatic threshold that triggered qualitative transformations in ice-sheet development. Cessation of major WAIS growth after ~0.9 Ma aligns with stabilized long-term CO<sub>2</sub> levels and ocean temperatures. Collectively, these results underscore the high sensitivity of the Amundsen Sea sector to global climate forcing.