Glacier

In the past, glaciers covered more than 33% of the earth’s surface. However, due to climate change, they are melting, and today, they only occupy around 10% of the earth’s surface.

A glacier is a large slow moving body of ice. They form when snow accumulates over many years and turns into ice. Eventually, when it becomes thick enough, it flows like a river over land due to the influence of gravity, a process known as glacier flow. As the glacier moves, it carves out valleys, leaving behind rocks and creating features such as lakes and waterfalls.

Glaciers practically exist on every continent. However, Antarctica and Greenland contain most of the world’s glacial ice.  

Additionally, glaciers can persist for many centuries and even millennia. The longest-living glacier on record is the Barnes Ice Cap in Antarctica, which has been around for more than 115,000 years.

Formation of Glaciers

For glacial ice to form, a large amount of snow must accumulate. Therefore, a glacier forms when piles of snowflakes compress and condense into ice.  

With time, when the glacier becomes big enough, it slowly flows downhill under the influence of its weight and gravity. And as it does, it grinds the rocks beneath it, carving out valleys and mountains.

Since the rate of glacial ice formation is highly dependent on snowfall, this transformation process can take several decades to hundreds of years.

Besides snowfall, the temperatures must be cold enough to keep the ice condensed all year round. As a result, glaciers tend to occur only in polar regions such as Greenland and Antarctica and at high altitudes such as South America and Alaska.

Types of Glaciers

In general, glaciers are classified into two groups: alpine glaciers, which are also known as mountain glaciers, and ice sheets, which are also referred continental glaciers.

Alpine glaciers form in the mountains at high elevations or near cool and wet coastal areas. However, most of the world’s alpine glaciers are found in high mountain ranges such as the Alps, Rockies, and the Andes.

Compared to ice sheets, alpine glaciers are much smaller and are found in areas with a lot of snowfall. The snowfall turns into ice and slowly moves down the mountainside. As the ice flows, it melts and forms rivers and valleys.

On the other hand, ice sheets are huge masses of ice covering a large geographical area. They are found in very cold places with very little precipitation, mainly in Greenland and Antarctica. Ice sheets are very old, thick, and dome-shaped. 

As ice sheets move, they cover vast areas, including plains, valleys, and even mountains. However, they flow very slowly and can take thousands of years to move just a few meters.

How Do Glaciers Change The Landscape?

The glacial movement is very powerful, and its impact on the bedrock is important in forming most of the world’s iconic landforms. It shapes the landscape through erosion and deposition.

With erosion, as the glacier moves downhill, it picks up rocks and boulders, which freeze in the glacier, eroding and carving the bedrock underneath. They often curve out U-shaped valleys with vertical cliffs.

In addition, glacial erosion also forms hills, deepens streambeds, and creates basins that eventually become lakes. For example, The Great Lakes of the United States were carved during the last ice age as the glaciers retreated.

Deposition is another way through which glaciers alter the landscape. A deposition is what a glacier leaves behind when it retreats or melts. As they move, glaciers deposit what they have picked on the way. And this includes boulders, sand, gravel, and soil. These materials are referred to as glacial till.

The material that a glacier picks up or pushes as it moves forms moraines. A moraine accumulates glacial till to form either a ridge or a mound. There are three types of moraines;

1. Lateral moraine: Forms when materials are deposited along both edges of a moving glacier
2. Medial moraine: Forms when materials are deposited at the center of where two glaciers meet. 
3. Terminal moraine: Forms when materials are deposited at the end of a glacier.

One of the most distinctive landform features that moraines forms are drumlins. Drumlins are hills, and they vary in size. However, they are characterized by a steep side and a sloping side. The sloping side is usually the side that is closest to the glacier as it retreats.  

The Importance of Glaciers

First, glaciers are a key source of freshwater. They store a large amount of freshwater, which is essential for humans, animals, and plants.

Second, they help regulate the earth’s temperature. They do this by reflecting excess radiation into space, thus cooling the planet.

Third, they also serve as important indicators of climate change and global warming. This is because any physical change in them provides a clear indication of the rate of temperature changes.

Additionally, glacial till, which is deposited by glaciers as they move, offers fertile soil for crop cultivation.

How Does Climate Change Affect Glaciers?

As each day passes, our planet is getting warmer. Temperatures are rising at a faster rate than before. The emission of greenhouse gases into the atmosphere significantly contributes to the rise of global temperatures. And as the planet gets warmer, glaciers are shrinking at an alarming rate.

The melting of glaciers highly contributes to the rising sea levels. This leads to increased coastal erosion and high storm surges caused by more frequent and powerful hurricanes and typhoons.

As of 2023, the Greenland and Antarctic ice sheets are melting four times faster than before and are significantly contributing to the global sea level rise.

Glaciers play an important role in the earth’s system; therefore, urgent conservation measures are required to minimize climate change and its effects on glaciers.

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