A new scientific study has raised concerns over the future of Antarctica’s Thwaites (Doomsday) Glacier, warning that its contribution to global sea-level rise by the end of this century could be twice as high as previously estimated. The findings suggest that scientists may have underestimated the pace of ice loss because existing climate models did not fully account for the processes taking place beneath the massive glacier.
Located in West Antarctica, Thwaites Glacier is widely known as the “Doomsday Glacier” because its potential collapse could accelerate the melting of the wider West Antarctic Ice Sheet and expose coastal communities across the world to greater flooding risks.
Researchers now estimate that the glacier alone could contribute up to 1.2 inches, or about 3 centimetres, to global sea levels by 2100. The findings were published in the journal *Nature Communications* following research conducted by scientists from the University of California, Irvine, and NASA’s Jet Propulsion Laboratory. The team developed an updated ice-sheet model to examine the glacier’s behaviour more accurately, particularly the interaction between ocean water and ice beneath its surface.
One of the key findings concerns the area where the glacier rests on the seabed before extending into the ocean as a floating ice shelf. Scientists have traditionally represented this boundary as a relatively narrow and stable line, known as the grounding line.
However, satellite observations indicate that this transition is actually a wider zone, sometimes extending several kilometres, through which seawater moves with the tides.
This process, known as tidal pumping, allows relatively warm ocean water to travel beneath the glacier, intensifying melting from below. As the ice thins, its contact with the seabed weakens, allowing more seawater to penetrate underneath and potentially accelerating the glacier’s retreat. The researchers incorporated this wider grounding zone into their model and compared the results with satellite observations of changes in the glacier’s thickness, movement and position over several decades.
The revised calculations produced projections of sea-level rise that were approximately twice those generated by earlier estimates. Another major concern is the possibility that Thwaites Glacier could lose contact with an underwater ridge that currently helps slow its movement towards the ocean. The study identified the Mouginot Ridge as a key feature supporting the glacier’s stability.
According to the researchers, there is an estimated 60 per cent probability that the ice could detach from this ridge by the end of the century. If that happens, the glacier could retreat more rapidly across the sloping seabed towards another underwater ridge, potentially increasing the rate at which ice flows into the ocean.
The underlying terrain is particularly important because sections of the seabed descend towards the Antarctic interior, allowing warm seawater to reach further beneath the ice as the glacier retreats. Thwaites is among the most closely monitored glaciers in Antarctica because of its potential influence on future sea levels.
Its ice loss currently accounts for around four per cent of the global rise in sea levels, making changes in its structure significant for climate researchers attempting to predict the long-term effects of global warming. The implications could extend well beyond the glacier itself. Thwaites acts as a natural barrier that helps restrain the enormous West Antarctic Ice Sheet. A substantial collapse could weaken this protective function and increase the risk of additional ice flowing into the ocean.
The complete loss of Thwaites alone could eventually raise global sea levels by more than two feet, while the destabilisation of the wider ice sheet could lead to a much larger rise. Even a relatively modest increase in sea levels can worsen coastal flooding, accelerate shoreline erosion and increase the damage caused by storm surges, particularly in low-lying cities and densely populated coastal regions.
The latest projections therefore underline the importance of improving scientific models to account for processes that may previously have been overlooked. The findings do not suggest that the glacier will collapse suddenly by 2100. Instead, they indicate that its contribution to sea-level rise could be greater than earlier projections suggested, highlighting the uncertainty surrounding the future of Antarctica’s rapidly changing ice sheets. Scientists continue to study the interactions between ocean temperatures, underwater terrain and the movement of Antarctic glaciers to improve forecasts of future ice loss.
The new research adds to evidence that understanding what happens beneath the ice is essential to assessing the risks facing coastal populations in the coming decades. The study also reinforces the need for sustained climate research and measures to limit global warming, as the long-term stability of Antarctica’s glaciers remains closely linked to changes in the surrounding ocean and the wider climate system.
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