The key facts

  • Thwaites Glacier could contribute up to 30 mm of sea level rise by 2100, versus the previous 15 mm — a study in Nature Communications.
  • Since 2000, the glacier has lost more than 1 trillion tons of ice, losing about 50 billion tons per year.
  • The probability of detachment from the Mugins Ridge by 2100 is about 60%, possibly as early as the late 2030s.

The glacier is melting faster than thought

The Thwaites Glacier in West Antarctica is melting significantly faster than previous models assumed, and by 2100 it could contribute roughly twice as much to global sea level rise as expected. This is the conclusion of a study published this week in Nature Communications. Scientists found that warm ocean water penetrates several kilometers beneath the ice and erodes it from below. According to the new estimates, even without additional warming beyond recent conditions, the glacier could add up to 30 mm (1.2 inches) to sea level by 2100, whereas traditional ice sheet models figured about 15 mm (0.6 inches).

The 'Doomsday Glacier' and its scale

Thwaites has been nicknamed the 'Doomsday Glacier' because of the potentially severe consequences of its collapse. It covers about 192,000 sq. km (74,000 sq. miles) — roughly the area of Senegal, larger than the state of Florida. The glacier is part of the West Antarctic Ice Sheet and, together with others, including the Pine Island Glacier, serves as a barrier holding back vast masses of interior ice. It currently accounts for about 4% of global sea level rise; since 2000 it has lost more than 1 trillion tons of ice, and losses continue at a rate of about 50 billion tons per year. The glacier has been closely monitored since the 1980s, when its rapid retreat was discovered. Warm ocean water is considered the key factor, and warming linked to fossil fuel emissions raises ocean temperatures and increases pressure on glaciers worldwide.

Tidal pumping and the risk of detachment from the ridge

The study focused on the glacier's 'grounding zone' — the area where ice resting on bedrock begins to float. Previous models often treated the grounding line as a fixed boundary; the authors instead modeled a wider zone where tides repeatedly raise and lower the ice, allowing warm water to penetrate deeper beneath it. Lead author Mattia Poinelli, a research fellow at UCLA, explained that this 'tidal pumping' delivers warm water deep under the ice and causes intense melting. The new modeling also points to the risk that Thwaites will lose contact with the underwater Mugins Ridge, which currently restrains its movement. Simulations consistent with recent observations showed about a 60% probability of such detachment by 2100 — possibly as early as the late 2030s. The researchers warned that this could accelerate the glacier's retreat and expose coastal communities worldwide to greater risk of sea level rise and flooding than previously assumed.