Better Antarctic collapse models refine global sea-level rise forecasts

Approximately one third of the world's population lives within a day's walk of a coastline. For these communities, rising seas are not a distant threat but an imminent reality that will reshape cities and infrastructure by the end of this century. Every single centimeter of sea-level rise could displace 1.5 million people, which means even modest changes have massive human consequences on a global scale.

The current range of uncertainty

Present estimates for how much sea levels will rise by the end of the 21st century vary widely from half a meter to two meters. That is roughly 1.6 feet to 6.6 feet, and the difference between those two numbers determines whether hundreds of millions of people need radical adaptation measures or more modest planning. The uncertainty stems largely from how fast Antarctic glaciers will collapse into the sea as temperatures continue to climb.

The new models focus on these glacial collapses in Antarctica. By simulating how ice shelves break away and what happens when warm water reaches the grounding lines, researchers can produce a more reliable prediction of where the final number will land. This is critical because coastal infrastructure - ports, roads, power plants, and residential neighborhoods - requires decades to adapt or relocate. A city that builds sea walls for half a meter of rise may find them useless if the actual rise reaches two meters.Why better models matter now

Reliable forecasting allows governments and communities around the world to prepare in advance rather than reacting after damage has already occurred. Improved Antarctic collapse simulations narrow the gap between the low and high estimates, giving planners a clearer picture of what to build for. Whether sea levels rise by 0.5 meters or 2 meters will dictate which coastal cities need seawalls and which can afford gradual adaptation over several decades.