Iceberg

Iceberg describes a large piece of ice that calves, or breaks away, from a glacier or ice shelf and drifts in the ocean. Because ice is less dense than seawater, only about one-ninth of an iceberg sticks above the surface, while the rest remains hidden below.

Icebergs form primarily in polar regions. In greenland and Antarctica, glaciers creep toward the coast and fracture. Ice shelves—floating extensions of ice sheets—also shed tabular bergs the size of cities. Winds and currents push icebergs into shipping lanes or toward warmer latitudes where they eventually melt.

Not all icebergs are the same shape. Tabular bergs look like flat-topped mesas, while pinnacled bergs feature jagged peaks. Melting, cracking, and rolling over time sculpt caves, arches, and turquoise streaks. Smaller chunks are called bergy bits or growlers.

Icebergs play ecological roles. As they melt, they release trapped minerals that fertilize plankton blooms, supporting krill, fish, and whales. Floating ice also influences local climate by reflecting sunlight back into space.

Navigation charts, satellites, and aircraft patrols track iceberg positions to protect ships—an effort that began after the Titanic disaster in 1912. climate warming accelerates iceberg calving, raising concerns about sea-level rise and changing ocean circulation.