How do Antarctic glaciers and ice shelves produce icebergs?

In Antarctica, icebergs are primarily produced through a process called calving, which occurs when large sections of ice shelves or glacier tongues fracture and break away into the ocean.1

How Calving Occurs

Ice shelves are floating extensions of the continental ice sheet that move seaward under the pressure of ice flowing from the interior. Because these shelves naturally contain cracks and crevasses, they eventually fracture to release icebergs. Several factors trigger this process:1

• Environmental Stress: The seaward front of an ice shelf is subjected to stresses from ocean swells, tides, and currents. Long-distance storm swells can cause bending stress that leads to fracturing.1
• Physical Impacts: Collisions with other icebergs can trigger immediate calving events.1
• Meltwater and Frost Wedging: During warmer periods, surface meltwater can fill crevasses. As this water refreezes, it expands—a process known as frost wedging—which can cause the shelf to splinter and disintegrate.1
• Glacier Tongues: Fast-flowing glaciers that protrude into the ocean create narrow ice shelves that are particularly susceptible to oscillating and fracturing due to wave action.1