Glaciologists from the University of California, Irvine and NASA’s Jet Propulsion Laboratory have found that Thwaites Glacier in West Antarctica is melting more rapidly than previously estimated, potentially doubling its projected contribution to global sea level rise. A study published on Monday, October 12, 2026, in Nature Communications, indicates that the glacier could contribute up to 1.2 inches to sea levels by 2100, even without additional global warming.
Thwaites Glacier has been retreating for decades and currently accounts for approximately 4% of global sea level rise. Scientists have historically monitored the glacier's "grounding line," the point where the ice leaves the seabed and begins to float. However, researchers used new modeling to show this area is actually a "grounding zone" miles wide.
In this zone, a process called "tidal pumping" allows warm seawater to flush in and out with the tides, penetrating deep beneath the ice. This movement causes what lead author Mattia Poinelli described as "vigorous melting" that was not fully captured in previous models. The study also found a 60% chance that the ice will "unpin" from the underwater Mouginot Ridge by 2100, which would likely lead to a faster retreat down the sloping bedrock.
The study identifies a threat to coastal communities, ranging from Miami to Manila, by increasing the anticipated scale of sea level rise. While 1.2 inches by 2100 may seem small, scientists state it magnifies the risk of coastal flooding. Thwaites holds enough water to raise global sea levels by more than 2 feet on its own; however, it also acts as a "cork" for the wider Antarctic ice sheet. If the entire sheet were to be released, sea levels could rise by an estimated 10 feet.
The study suggests that even if planet-heating pollution is reduced now, some of this sea level rise is likely already locked in due to existing damage to the ice sheet's underside.
Outside experts, including Robert Larter of the British Antarctic Survey, noted that the environment beneath the glacier is even more complex than the study describes and that more direct data is required for confident predictions. To address this, researchers are planning a mission to the glacier in 2028 to deploy instruments that can document the movement of seawater. Until that observational data is collected, the exact timing of a potential collapse remains a variable in climate forecasting. Areas at risk of flooding will continue to monitor these projections as they plan infrastructure.