A new study in Nature Geoscience has revealed that the East Antarctic Ice Sheet experienced a major retreat around 9,000 years ago due to a chain reaction driven by shifting ocean conditions. The research shows that meltwater discharged from collapsing ice shelves altered ocean layers, enabling warm deep water to move closer to Antarctica’s coastline and accelerate further melting.
The findings were led by Professor Yusuke Suganuma of the National Institute of Polar Research and SOKENDAI, with contributions from over 30 global research institutions. The study focused on marine sediment cores collected from Lützow-Holm Bay near Syowa Station, using data from decades of Japanese Antarctic Research Expeditions. Geological evidence was combined with analysis of beryllium isotope ratios and advanced climate–ocean simulations.
According to the researchers, the warm Circumpolar Deep Water intensified in the region about 9,000 years ago, causing floating ice shelves to collapse. Once these shelves disappeared, the inland ice they once held back began flowing more rapidly into the sea, accelerating ice loss and contributing to sea-level rise.
Climate models used in the study suggest that meltwater from other parts of Antarctica played a critical role in reinforcing the process. As meltwater spread across the Southern Ocean, it increased stratification by forming a fresher, lighter surface layer. This limited mixing with colder water above, allowing warm deep water to intrude more effectively beneath ice shelves. The result was a self-sustaining feedback loop that amplified melting across widely separated regions.
Researchers say these past events closely resemble processes now underway in West Antarctica, where glaciers such as Thwaites are retreating rapidly as warm water erodes their bases. If similar cascading feedbacks intensify under current global warming, widespread ice loss could accelerate, contributing significantly to long-term sea-level rise.
The study provides new insight into how interconnected ocean and ice systems respond to warming. Scientists argue that understanding these past dynamics is essential for improving predictions of future changes in the Antarctic Ice Sheet, which holds enough water to raise global sea levels by tens of meters.
Professor Suganuma noted that the research highlights how localized melting can trigger far-reaching impacts. He said the findings underscore the need for continued monitoring and global cooperation to assess and plan for future ice loss in Antarctica.