The Thwaites Glacier: Antarctica's Most Dangerous Ice

🌊 The Thwaites Glacier: Antarctica's Most Dangerous Ice

While the Arctic grabs headlines for sea ice loss, Antarctica's contribution to global sea level rise is potentially far more significant — and the Thwaites Glacier is the most closely watched piece of ice on Earth.

Why Thwaites Matters

Thwaites Glacier in West Antarctica is approximately 120 km wide — roughly the size of Florida. It is currently losing approximately 50 billion tonnes of ice per year to the ocean. On its own, Thwaites currently contributes around 4% of global sea level rise. But its collapse would be a gateway to far greater losses.

The West Antarctic Ice Sheet (WAIS) sits on bedrock that is largely below sea level and slopes downward away from the coast — making it potentially vulnerable to "marine ice sheet instability." The concern: if Thwaites retreats far enough, warmer ocean water could get beneath the entire ice sheet and the retreat could become self-sustaining and irreversible. If the WAIS were to fully collapse — a process that could unfold over decades to centuries — it could raise global sea levels by up to 3.3 metres.

The Thwaites "Doomsday Glacier" Nickname

Scientists have nicknamed Thwaites the "Doomsday Glacier" — not because collapse is certain or imminent, but because the stakes are so high. A 2023 study using an underwater robot found that the base of Thwaites is melting far faster than previous models predicted, in part because warm water is flowing into previously unknown crevices beneath the ice. The ice shelf that holds the glacier back from the ocean could break apart within a decade.

The IPCC (2021) classifies a major WAIS contribution to sea level rise as a low probability but high impact risk — exactly the type of risk that requires precautionary management even without certainty.