Flying over Antarctica, it’s difficult to understand what all the fuss is about. The snow frosting on top of the world’s largest ice sheet looks smooth and unblemished, beautiful and perfectly white, like a gigantic wedding cake. The surface is covered in small swirls of snow dunes.

However, as you approach the ice sheet’s edge, a sense of tremendous underlying power emerges. Cracks appear on the surface, sometimes organized like a washboard, sometimes a total chaos of spires and ridges, revealing the pale blue crystalline heart of the ice beneath.

The size of these breaks grows steadily as the plane descends. These aren’t just cracks, but canyons the size of a jetliner or spires the size of monuments. Cliffs and tears, rips in the white blanket appear, indicating a force capable of tossing city blocks of ice around like a pileup of wrecked cars. It’s a twisted, ripped, and wrenched landscape.

A sense of movement emerges as well, in a way that no ice-free region of the Earth can convey—the entire landscape is in motion, and it appears to be unhappy about it.

Antarctica is a continent made up of several large islands, one of which is the size of Australia, that are all buried beneath a 10,000-foot layer of ice. The ice contains enough fresh water to raise the sea level by nearly 200 feet.

Its glaciers have always been moving, but beneath the ice, changes are taking place that will have far-reaching consequences for the ice sheet’s future—and for coastal communities around the world.

My workplace is in Antarctica. In more than 20 trips to the continent as a polar scientist, I’ve visited most areas of the ice sheet, bringing sensors and weather stations, trekking across glaciers, or measuring the speed, thickness, and structure of the ice.

Early on, changes in the ice were gradual. Icebergs would break off, but they were quickly replaced by new outflow. Total snowfall had not changed much in centuries—we knew this from ice cores—and the flow of ice and elevation of the ice sheet seemed so constant in general that one of the main goals of early ice research in Antarctica was to find a place, any place, that had changed dramatically.

However, as the surrounding air and ocean warm, previously stable areas of the Antarctic ice sheet are breaking, thinning, melting, or collapsing in a heap. As the ice’s edges react, they send a powerful message: If even a small portion of the ice sheet collapses into the sea, the consequences for the world’s coasts would be severe.

Recent efforts to combine data from hundreds of planes and ground-based studies have resulted in a map of the continent beneath the ice. The Transantarctic Mountains separate two very different landscapes.

East Antarctica, the region closest to Australia, is rugged and furrowed, with several small mountain ranges. Some of these have alpine valleys formed by the first glaciers that formed on Antarctica 30 million years ago, when the climate was similar to that of Alberta or Patagonia. The bedrock of East Antarctica is mostly above sea level. This is where the city-sized Conger ice shelf collapsed in March 2022 during an unusually intense heat wave.

West Antarctica’s bedrock is very different, with much deeper sections. This was once the ocean floor, a region where the continent was stretched and broken into smaller blocks separated by a deep seabed. The thick blanket of ice connects large islands formed by volcanic mountain ranges. However, the ice is warmer and moving faster here.

This area was most likely an open ocean 120,000 years ago, and it has been for the last 2 million years. This is significant because our current climate is rapidly approaching temperatures similar to those of a few million years ago.

The realization that the West Antarctic ice sheet has vanished is a major source of concern in the age of global warming.