A 2026 modeling study published in Communications Earth & Environment warns the West Antarctic Ice Sheet may be nearing a tipping point where even minimal deep-ocean warming—just 0 to 0.25°C above current levels—could trigger irreversible retreat. Unlike surface air temperatures, this threshold refers to warming in deep ocean currents around Antarctica that erode floating ice shelves from below. These shelves act as brakes for inland glaciers; once weakened, glacier flow accelerates, initiating a self-reinforcing cycle known as marine ice sheet instability. The study draws on 800,000 years of simulated climate history to show how West Antarctica repeatedly shifted into retreat during past warm periods, unlike the more stable East Antarctic Ice Sheet.

The collapse would not lead to sudden sea-level rise. Instead, it would unfold over centuries or millennia, eventually contributing over 4 meters (about 13 feet) to global sea levels. However, the critical decisions that determine whether this path is avoided must be made much sooner. The Amundsen Sea sector, home to the Thwaites and Pine Island glaciers, is identified as a key region where tipping could begin. These glaciers are already experiencing observed retreat, raising concerns about near-term vulnerability.

Coastal regions worldwide would face profound long-term risks, from megacities like Miami and Shanghai to low-lying deltas and island nations. Saltwater intrusion, repeated flooding, port disruptions, and infrastructure damage would compound challenges, with disproportionate impacts on lower-income communities. While the full rise is distant, the study underscores that today’s choices in emissions and monitoring could determine whether future generations inherit this trajectory.