Researchers at the University of California, Irvine, and NASA’s Jet Propulsion Laboratory have developed an updated computer model that significantly revises projections for sea level rise from Antarctica’s Thwaites Glacier. The findings, published in Nature Communications, indicate the glacier could contribute approximately 30 millimeters to global sea level rise by 2100, double earlier estimates, even without additional climate warming.
The new model addresses a key limitation in previous scientific approaches. Traditional models treated the boundary between grounded and floating ice as a narrow, stable line. The updated version accounts for a much broader transitional zone where ocean water penetrates several kilometers beneath the glacier’s surface. This refinement allows the model to reproduce historical changes in Thwaites from the 1990s onward with far greater accuracy than conventional models, capturing ice loss rates four times more pronounced than previously represented.
Satellite observations, including data from Finland’s ICEYE constellation, revealed that seawater travels deep under grounded ice through a “grounding zone” measuring several kilometers wide. As tides fluctuate, ocean water repeatedly lifts the ice and exposes its underside to warm, pressurized seawater. These warm currents, altered by climate change, accelerate melting beneath the glacier and weaken its connection to underwater ridges that provide structural support.
The research team determined that the Mouginot Ridge currently provides critical stability to Thwaites’ main trunk. Model simulations suggest a 60 percent probability that the glacier will become detached from this underwater anchor before 2100, after which it would retreat more rapidly across the seafloor. Such a development would accelerate ice loss and substantially increase coastal flooding risks in the coming decades, according to the researchers.
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