Iceberg

An iceberg is a large piece of freshwater ice that has calved from a glacier or ice shelf and is floating in the ocean. Icebergs form in polar and subpolar regions, most notably around Antarctica and Greenland, where glaciers reach the sea and break away. They vary widely in size and shape, from small bergy bits and growlers to sprawling tabular icebergs that can be several kilometers long.

An iceberg is composed of freshly frozen water. Because ice is less dense than seawater, only a portion of an iceberg remains above the waterline; roughly one-tenth of its volume is visible, with the vast majority submerged. The color of icebergs ranges from white to deep blue, the latter indicating dense, bubble-free ice.

Icebergs drift with ocean currents and wind. Their trajectories are influenced by regional circulation and air temperature, and they melt as they travel, losing mass from both their sunlit surfaces and their submerged parts. Lifetimes can be months to years, depending on size and conditions.

Historically, icebergs have posed hazards to ships, the most famous example being the sinking of the RMS Titanic in 1912 after a collision with an iceberg. To reduce risk, the International Ice Patrol monitors ice conditions in the North Atlantic and issues warnings during the shipping season.

Climate factors influence iceberg production and melt. Warming temperatures affect calving rates from glaciers and the rate at which floating ice melts, altering iceberg supply and drift patterns in some regions. Icebergs also contribute freshwater to seawater and can influence local ecology and ocean stratification as they melt.