In the farthest reaches of Antarctica, a nightmare scenario of crumbling ice – and rapidly rising seas – could spell disaster for a warming planet.

As the world warms, determining exactly how quickly ice melts and seas rise may be one of the most important questions of our time. Half the world’s population lives within 50 miles of a coastline. Trillions of dollars of real estate is perched on beaches and clustered in low-lying cities like Miami and New York. A long, slow rise of the waters in the coming decades may be manageable. A more abrupt rise would not be...

In the farthest reaches of Antarctica, a nightmare scenario of crumbling ice – and rapidly rising seas – could spell disaster for a warming planet.

As the world warms, determining exactly how quickly ice melts and seas rise may be one of the most important questions of our time. Half the world’s population lives within 50 miles of a coastline. Trillions of dollars of real estate is perched on beaches and clustered in low-lying cities like Miami and New York. A long, slow rise of the waters in the coming decades may be manageable. A more abrupt rise would not be...