Glacier vs. Iceberg

Main Difference

The main difference between Glacier and Iceberg is that the Glacier is a large persistent body of ice and Iceberg is a large piece of fresh-water ice floating in the ocean or other body of water.

• Glacier

  A glacier (US: or UK: ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation (melting and sublimation) over many years, often centuries. Glaciers slowly deform and flow due to stresses induced by their weight, creating crevasses, seracs, and other distinguishing features. They also abrade rock and debris from their substrate to create landforms such as cirques and moraines. Glaciers form only on land and are distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water.

  On Earth, 99% of glacial ice is contained within vast ice sheets (also known as “continental glaciers”) in the polar regions, but glaciers may be found in mountain ranges on every continent including Oceania’s high-latitude oceanic island countries such as New Zealand. Between 35°N and 35°S, glaciers occur only in the Himalayas, Andes, Rocky Mountains, a few high mountains in East Africa, Mexico, New Guinea and on Zard Kuh in Iran. Glaciers cover about 10 percent of Earth’s land surface. Continental glaciers cover nearly 13 million km2 (5 million sq mi) or about 98 percent of Antarctica’s 13.2 million km2 (5.1 million sq mi), with an average thickness of 2,100 m (7,000 ft). Greenland and Patagonia also have huge expanses of continental glaciers. The volume of glaciers, not including the ice sheets of Antarctica and Greenland, has been estimated as 170,000 km3.Glacial ice is the largest reservoir of fresh water on Earth. Many glaciers from temperate, alpine and seasonal polar climates store water as ice during the colder seasons and release it later in the form of meltwater as warmer summer temperatures cause the glacier to melt, creating a water source that is especially important for plants, animals and human uses when other sources may be scant. Within high-altitude and Antarctic environments, the seasonal temperature difference is often not sufficient to release meltwater.

  Since glacial mass is affected by long-term climatic changes, e.g., precipitation, mean temperature, and cloud cover, glacial mass changes are considered among the most sensitive indicators of climate change and are a major source of variations in sea level.

  A large piece of compressed ice, or a glacier, appears blue, as large quantities of water appear blue. This is because water molecules absorb other colors more efficiently than blue. The other reason for the blue color of glaciers is the lack of air bubbles. Air bubbles, which give a white color to ice, are squeezed out by pressure increasing the density of the created ice.

• Iceberg

  An iceberg is a large piece of freshwater ice that has broken off a glacier or an ice shelf and is floating freely in open (salt) water. Another name for iceberg is “ice mountain”. Small bits of disintegrating icebergs are called “growlers” or “bergy bits”.

  Icebergs are possible on Earth because the oceans are filled with liquid water, a substance less dense when solid than liquid. Planets with oceans consisting of different substances like methane cannot have icebergs, as their chunks of frozen liquid would sink.

  Because 90 percent of an iceberg is below the surface and not visible, icebergs have been considered a serious maritime hazard ever since the 1912 loss of the “unsinkable” RMS Titanic, leading to the formation of the International Ice Patrol in 1914.

  The expression “tip of the iceberg”, illustrates a difficulty that is only a small, visible part of a larger, complex problem.

  The largest iceberg ever reliably recorded was Iceberg B-15A which split off the Ross Ice Shelf in Antarctica in 2000.

• Iceberg (noun)

  a large floating mass of ice detached from a glacier or ice sheet and carried out to sea.