The Thwaites Glacier, often called the “Doomsday Glacier” due to its potential impact on global sea levels, is undergoing rapid change. A new study reveals growing concerns about a critical floating extension of this glacier, the Thwaites Eastern Ice Shelf (TEIS), and its accelerated destabilization. Understanding these changes is vital as the future of this glacier remains a key factor in projecting future sea-level rise.
TEIS: A Stabilizing Force Under Pressure
TEIS is partially supported and anchored at its northern edge by a key “pinning point.” This point acts as a buffer, preventing the ice shelf from rapidly breaking apart and flowing into the ocean. However, over the past two decades, fractures have been progressively appearing and expanding around a major fracture zone located upstream of this pinning point.
A Detailed Look at Ice Shelf Weakening
The study, published in the Journal of Geophysical Research: Earth Surface, provides a detailed account of how the TEIS has been gradually disintegrating over the last twenty years. Led by Debangshu Banerjee, a recent graduate from the Center for Earth Observation Sciences (CEOS), the research involved collaboration with Dr. Karen Alley (Assistant Professor, CEOS) and Dr. David Lilien (Assistant Professor, Indiana University Bloomington and former Research Associate at CEOS). The team also benefited from the expertise of renowned glaciologists like Dr. Ted Scambos, Dr. Martin Truffer, Dr. Adrian Luckman, and Dr. Erin Pettitt.
Tracking the Evolution of Fractures
The study is part of the TARSAN (Thwaites-Amundsen Regional Survey and Network) project, a component of the International Thwaites Glacier Collaboration (ITGC). The ITGC is a large-scale, joint U.S.–U.K. initiative dedicated to researching the processes driving change in the Thwaites Glacier.
By analyzing two decades (2002–2022) of satellite imagery, measuring ice flow speed, and recording GPS data from the ice shelf, the team mapped the development of fractures within the TEIS shear zone and how they relate to changes in ice behavior. Their findings indicate that the slow formation of these fractures is causing the shelf to detach from its pinning point. This detachment, in turn, is speeding up the flow of ice upstream and weakening the shelf’s overall stability.
Four Stages of Destabilization and a Feedback Loop
The researchers identified four distinct phases in the process of ice-shelf weakening and revealed two key insights.
- Fracture Development in Two Phases: Initially, long fractures formed running parallel to the direction of ice flow. Later, shorter fractures developed oriented perpendicular to the ice’s movement.
- A Positive Feedback Loop: The study discovered evidence of a self-reinforcing cycle: fractures weaken the ice shelf, which leads to accelerated ice flow, causing further fracturing and weakening. This cycle intensified the shelf’s disintegration in recent years.
Pinning Point Turns Destabilizing
The study highlights a crucial shift: a once-stabilizing pinning point has gradually become a driver of instability through four clear stages. This pattern of ice-shelf disintegration may serve as a cautionary sign for other Antarctic ice shelves exhibiting similar weakening signs.
The ongoing loss of these floating ice shelves could substantially increase the Antarctic Ice Sheet’s contribution to rising sea levels. Understanding these dynamics is vital for more accurate predictions and preparedness against the effects of climate change.
