Glaciers

Glaciers

A glacier in the mountains

A glacier is a persistent body of dense ice that is constantly moving under its own weight. It forms where the accumulation of snow exceeds its ablation (melting and sublimation) over many years, often centuries. Glaciers are the largest reservoirs of freshwater on Earth, holding about 69% of the world's fresh water.

Formation

Glaciers form in areas where more snow falls in winter than melts in summer. Over time, layers of snow compress and recrystallize, forming dense ice. This process can take hundreds to thousands of years. The ice in glaciers is not static; it flows like a very slow river, deforming and moving due to its own weight.

Types of Glaciers

There are several types of glaciers, including:

• Valley glaciers: These glaciers flow down valleys and are often found in mountainous regions.
• Ice sheets: Massive glaciers that cover more than 50,000 square kilometers. The two current ice sheets are the Antarctic ice sheet and the Greenland ice sheet.
• Ice caps: Smaller than ice sheets, these glaciers cover less than 50,000 square kilometers.
• Piedmont glaciers: These glaciers spread out at the base of mountains.
• Tidewater glaciers: Glaciers that terminate in the sea, often calving to form icebergs.

Movement

Glaciers move through two primary mechanisms: internal deformation and basal sliding. Internal deformation occurs when the weight of the ice causes it to deform and flow. Basal sliding happens when the glacier slides over the bedrock due to a layer of meltwater at its base.

Impact on the Environment

Glaciers have a significant impact on the environment. They shape landscapes through processes like glacial erosion and deposition. Glaciers carve out valleys, create fjords, and deposit moraines. They also influence global sea levels; when glaciers melt, they contribute to sea level rise.

Climate Change and Glaciers

Glaciers are sensitive indicators of climate change. Many glaciers around the world are retreating due to rising global temperatures. This retreat can lead to reduced freshwater availability for communities that rely on glacial meltwater.

Notable Glaciers

Some of the most well-known glaciers include:

• Hubbard Glacier in Alaska
• Perito Moreno Glacier in Argentina
• Vatnajökull in Iceland
• Aletsch Glacier in Switzerland

See Also

• Iceberg
• Snow
• Ice cap
• Antarctic ice sheet
• Greenland ice sheet
• Glacial erosion
• Sea level rise