A groundbreaking study published in Nature Geoscience has unveiled a pivotal mechanism driving the dramatic retreat of the East Antarctic Ice Sheet (EAIS) approximately 9,000 years ago. This extensive ice loss event was not a simple regional occurrence but was propelled by an intricate self-reinforcing feedback loop between glacial melt and oceanic circulation patterns. Spearheaded by Professor Yusuke Suganuma of the National Institute of Polar Research (NIPR) and the Graduate University for Advanced Studies (SOKENDAI), the research delineates how the inflow of warm, deep Circumpolar Deep Water (CDW) into the coastal regions of East Antarctica led to the destabilization and subsequent collapse of ice shelves. The disappearance of these shelves crucially reduced the buttressing effect on inland ice masses, accelerating the flow and melting of the continental ice sheet.
This discovery fundamentally shifts our understanding of ice sheet dynamics by illustrating that meltwater influenced processes in one sector can propagate through oceanic pathways to amplify melting across disconnected regions. This phenomenon, described as a “cascading positive feedback,” underlines a vital feedback mechanism that has profound implications for anticipating future ice sheet vulnerability under ongoing global warming. In essence, the study reveals how the East Antarctic Ice Sheet’s deglaciation was intricately linked to alterations in ocean stratification and circulation caused by meltwater input, leading to a self-sustaining cycle of ice loss that could inform modern ice sheet projections.
To unravel the mechanism behind such an ancient ice-sheet collapse, the research team analyzed marine sediment cores retrieved from Lützow-Holm Bay, near Japan’s Syowa Station, collected over decades of Japanese Antarctic Research Expeditions (JARE), including recent missions using the icebreaker Shirase. These sedimentary deposits served as archives chronicling past environmental variations. By deploying a suite of sophisticated sedimentological, micropaleontological, and geochemical methodologies, with a particular focus on beryllium isotope ratios (10Be/9Be), the team was able to reconstruct temperature, oceanic conditions, and ice mass changes with remarkable resolution. The data revealed a pronounced intensification of warm Circumpolar Deep Water in the bay about 9,000 years ago, coinciding with the disintegration of ice shelves and the consequential acceleration of ice mass flow from the interior.
The sediment core analyses were complemented by comprehensive geomorphological and geological field surveys conducted in Dronning Maud Land, reinforcing the underwater evidence with terrestrial geomorphic signatures of past ice-sheet retreat. These multidisciplinary observations painted a detailed portrait of early Holocene environmental conditions, indicating that warming oceans played a direct and critical role in triggering the East Antarctic Ice Sheet’s retreat. This multidisciplinary approach exemplifies the integration of marine and terrestrial geological data necessary to reconstruct ice sheet dynamics over millennial timescales.
Utilizing climate and high-resolution ocean circulation models, the researchers sought to simulate the feedback processes driving deep warm-water intrusions. Their modeling revealed that meltwater from ice shelves such as the Ross Ice Shelf contributed to surface freshening across the Southern Ocean. This freshening intensified vertical stratification by creating a low-density surface layer, which inhibited the typical upward mixing of colder waters. Consequently, the warmer deep waters were drawn closer to the continental shelf break, intensifying basal melting of floating ice shelves along the East Antarctic coastline. This physical mechanism generated a feedback loop where increased ice melt led to greater freshening, strengthening stratification, and further promoting warm water incursions beneath the ice shelves.
This self-reinforcing feedback process highlights a complex interconnectedness within the Antarctic ice-ocean system. Meltwater discharge in one sector alters ocean stratification and circulation patterns, which then exacerbates melting in remote regions through ocean teleconnections. Such “cascading” feedbacks suggest that regional ice-sheet destabilization may propagate continent-wide, amplifying the total ice mass loss and consequently accelerating global sea-level rise. This insight is crucial for refining projections of Antarctic contributions to future sea-level change and for assessing potential tipping points in ice-sheet stability.
Importantly, while this feedback mechanism was active during the early Holocene, a period marked by naturally elevated global temperatures relative to the glacial epoch, its relevance extends directly into the current era of anthropogenic climate warming. Observations of the modern West Antarctic Ice Sheet, particularly in vulnerable regions such as the Thwaites and Pine Island glaciers, reveal rapid retreat driven by similar mechanisms of warm deep-water intrusion. The study’s findings imply that if these cascading feedback loops are presently active or initiate soon, they could significantly hasten the pace of ice-sheet loss, thereby elevating future sea-level rise scenarios.
The research stands out not only for its scientific insights but also for its massive collaborative approach, involving over 30 institutions spanning Japan and international partners from New Zealand, Spain, and elsewhere. Entities such as the National Institute of Polar Research (NIPR), Japan Agency for Marine–Earth Science and Technology (JAMSTEC), the Geological Survey of Japan (AIST), as well as multiple universities, fused their expertise in geology, oceanography, climate modeling, and geochemistry. This interdisciplinary method facilitated a holistic reconstruction of past Antarctic climate and ice sheet dynamics and underscored the necessity of coordinated global efforts in understanding polar climate change.
Professor Yusuke Suganuma emphasized the broader implications, stating that this investigation delivers critical data and validated models that will augment the accuracy of future Antarctic ice-sheet behavior predictions. The identification of cascading feedback mechanisms compellingly demonstrates how subtle regional climatic or oceanographic changes may trigger extensive, system-wide impacts with far-reaching consequences. This reflects an urgent need for continued interdisciplinary polar research to decode the complex feedbacks shaping Earth’s climate system under warming conditions.
This study’s revelations about the East Antarctic Ice Sheet’s past behavior provide a valuable analog for interpreting ongoing and future changes. By exposing the intrinsic susceptibility of Antarctic ice shelves to warm ocean intrusions and feedback-amplified melt, it calls for heightened vigilance in monitoring oceanographic conditions surrounding Antarctica. The insights also highlight the vital role of high-resolution sediment core analyses combined with advanced numerical modeling in disentangling the interactions between ice sheets and ocean systems over geological time.
In conclusion, the findings chart a cautionary tale from Earth’s early Holocene past, illustrating how interconnected processes within the cryosphere and ocean can drive massive ice loss events. As global temperatures continue to rise, understanding these cascading feedbacks becomes ever more critical for anticipating potential nonlinear responses in polar ice stability and their implications for global sea level. This study significantly advances polar science by bridging paleo-records and modern climate dynamics, providing a robust framework for future research endeavors on ice-sheet vulnerability and resilience.
Subject of Research: Antarctic Ice Sheet Dynamics, Climate Feedback Mechanisms, Ocean Circulation, Ice Shelf Collapse
Article Title: Insights into the Self-Reinforcing Feedbacks Driving the Early Holocene East Antarctic Ice Sheet Retreat
News Publication Date: 2024
Web References:
http://dx.doi.org/10.1038/s41561-025-01829-7
References:
Suganuma, Y., et al. (2024). Nature Geoscience. DOI: 10.1038/s41561-025-01829-7
Image Credits:
The National Institute of Advanced Industrial Science and Technology (AIST)
Keywords:
East Antarctic Ice Sheet, Ice shelf collapse, Circumpolar Deep Water, Ocean stratification, Climate feedback, Ice melt, Paleoceanography, Marine sediment cores, Climate modeling, Antarctic research
