Antarctic last interglacial isotope peak in response to sea ice retreat not ice-sheet collapse

• Published in: Nature communications Vol. 7; no. 1; p. 12293
• Main Authors: Holloway, Max D., Sime, Louise C., Singarayer, Joy S., Tindall, Julia C., Bunch, Pete, Valdes, Paul J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16-08-2016; Nature Publishing Group; Nature Portfolio
• Subjects: Climate change; Climate models; Collapse; Computer simulation; Global warming; Humanities and Social Sciences; Ice; Isotopes; multidisciplinary; Polar environments; Science; Science (multidisciplinary); Sea ice; Sea level; Sea level rise
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms12293

Several studies have suggested that sea-level rise during the last interglacial implies retreat of the West Antarctic Ice Sheet (WAIS). The prevalent hypothesis is that the retreat coincided with the peak Antarctic temperature and stable water isotope values from 128,000 years ago (128 ka); very early in the last interglacial. Here, by analysing climate model simulations of last interglacial WAIS loss featuring water isotopes, we show instead that the isotopic response to WAIS loss is in opposition to the isotopic evidence at 128 ka. Instead, a reduction in winter sea ice area of 65±7% fully explains the 128 ka ice core evidence. Our finding of a marked retreat of the sea ice at 128 ka demonstrates the sensitivity of Antarctic sea ice extent to climate warming.
The peak in Antarctic ice core isotope values, 128,000 years before present, was concurrent with a significantly warmer-than-present Antarctic climate. Here, the authors show that this isotope maximum was associated with a major retreat of sea ice and not a collapse of the West Antarctic Ice Sheet.