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– Definition of a Glacier:
– Persistent body of dense ice
– Moves under its weight
– Forms from snow accumulation exceeding ablation
– Develops crevasses and seracs
– Flows slowly over time

– Geographic Distribution:
– Pakistan has 7,253 glaciers
– Pakistan holds most glacial ice outside polar regions
– Baltoro Glacier in Pakistan is 62 km long
– Glacier in Greenland’s Geikie Plateau
– Taschachferner in Austria’s Ötztal Alps

– Glacier Characteristics:
– Vary in size and shape
– Can create icebergs in oceans
– Influence climate through albedo effect
– Serve as freshwater reservoirs
– Erode and shape landscapes

– Glacier Movement:
– Moves due to gravity and pressure
– Speed influenced by slope and mass
– Internal deformation causes flow
– Basal sliding aids movement
– Seasonal variations in speed

– Impact of Climate Change:
– Accelerated melting rates
– Alters sea levels and ecosystems
– Increases glacial lake outburst floods
– Threatens freshwater resources
– Indicators of global warming trends

Glacier (Wikipedia)

A glacier (US: /ˈɡlʃər/; UK: /ˈɡlæsiər, ˈɡlsiər/) 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 over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water.

Glacier of the Geikie Plateau in Greenland.
The Taschachferner in the Ötztal Alps in Austria. The mountain to the left is the Wildspitze (3.768 m), second highest in Austria.
With 7,253 known glaciers, Pakistan contains more glacial ice than any other country on earth outside the polar regions. At 62 kilometres (39 mi) in length, the pictured Baltoro Glacier is one of the world's longest alpine glaciers.

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 other than the Australian mainland, including Oceania's high-latitude oceanic island countries such as New Zealand. Between latitudes 35°N and 35°S, glaciers occur only in the Himalayas, Andes, and a few high mountains in East Africa, Mexico, New Guinea and on Zard-Kuh in Iran. With more than 7,000 known glaciers, Pakistan has more glacial ice than any other country outside the polar regions. Glaciers cover about 10% of Earth's land surface. Continental glaciers cover nearly 13 million km2 (5 million sq mi) or about 98% of Antarctica's 13.2 million km2 (5.1 million sq mi), with an average thickness of ice 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 at 170,000 km3.

Glacial ice is the largest reservoir of fresh water on Earth, holding with ice sheets about 69 percent of the world's freshwater. 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. However, 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, 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 created ice's density.

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