Thwaites Glacier may raise sea levels twice as much as projected

Antarctica’s Thwaites Glacier is losing ice faster than previously understood and could contribute about twice as much to global sea-level rise by the end of the century as earlier projections suggested, according to Anadolu Agency.

Research published this week in “Nature Communications” found that warm ocean water is pushing several kilometers beneath the glacier and melting it from below.

The researchers estimate that this process could cause Thwaites to add up to 30 millimeters (1.2 inches) to global sea levels by 2100, even without additional warming beyond recent conditions. Conventional ice-sheet models had projected a contribution of roughly 15 millimeters (about 0.6 inches) by that year.

Warm water reaches beneath the glacier

Known as the “Doomsday Glacier” because of the potentially severe consequences of its collapse, Thwaites covers around 192,000 square kilometers (74,000 square miles) in West Antarctica—roughly the size of Senegal and larger than the US state of Florida.

It is part of the much larger West Antarctic Ice Sheet and, together with glaciers including Pine Island, acts as a barrier holding back vast quantities of inland ice.

Thwaites currently accounts for around 4% of global sea-level rise. It has lost more than 1 trillion tons of ice since 2000, with losses continuing at roughly 50 billion tons annually. Scientists have closely monitored the glacier since discovering in the 1980s that it was retreating rapidly.

Warm ocean water driven beneath the ice is considered a key factor. Human-caused climate change, particularly warming linked to fossil fuel emissions, is raising ocean temperatures and increasing pressure on glaciers worldwide.

The latest study focused on Thwaites’ “grounding zone,” where ice resting on bedrock begins to float on the sea. Earlier models often treated the grounding line as a fixed boundary, while the researchers modeled a broader zone where tides repeatedly lift and lower the ice, allowing warm seawater to penetrate farther underneath.

Lead author Mattia Poinelli, a project scientist at UCLA, said this “tidal pumping” enables warm water to reach deep beneath the ice and cause vigorous melting.

Possible detachment from underwater ridge

The new modeling also raises concerns that Thwaites could lose contact with the underwater Mouginot Ridge, which currently helps restrain its movement.

Simulations consistent with recent observations indicated around a 60% chance that the glacier will become detached from the ridge by 2100, potentially as early as the late 2030s.

Researchers warned that such a shift could accelerate the glacier’s retreat and expose coastal communities worldwide to greater sea-level rise and flooding risks than previously projected.