The Alpine Glaciers
Mountain or alpine glaciers are the ones that are formed on the mountainside and move downward over the mountainous slopes. It is possible for alpine glaciers to even create or deepen valleys as the accumulated ice exerts pressure over land, pushing it downwards. Alpine glaciers can be commonly found in almost all continents (except Australia). Some of the most famous alpine glaciers include Gorner Glacier in Switzerland and Furtwangler Glacier in Tanzania.
Ice Sheets
Unlike alpine glaciers, ice sheets are not limited to the mountainous region. Instead, they are more like a sheet of ice that spreads from the center in all directions. As the ice sheet spreads, it covers everything under the thick coat of ice, including plain areas, valleys and even mountains. Continental ice sheets are large ice sheets that cover a large area. As of now, the continental ice sheet covers most of Antarctica and Greenland.
Additionally, ice sheets covered much of Europe and North America during the Ice Age, when around 33% of the planet was covered with ice. As the climate changes, glacial ice sheets, so far cover only 10% of the land. Due to the ancient glacial ice sheets and the pressure they exerted on land, many of the landscapes on Earth exist in their present form.
How Do Glaciers Form?
It might come as a surprise, but it all starts with a snowflake. However, it takes an incredible amount of snow to form and pile up as a glacier. Once the snow accumulates, the snowflakes, given their structure, begin to compress each other and pile up each year. When the snow accumulates year after year, it changes from fluffy and soft snowflakes into round ice pellets. With new snow coming over the buried hardened snow, the latter hardens and becomes even more compressed. Eventually, it changes into dense, grainy ice, which is known as firm.
The process continues, and layers of firn build on top of each other. When the thickness of ice grows up to 160 feet, the firn changes from grainy ice into a solid mass, which is how a glacier is formed. However, it doesn’t happen overnight. This process of formation takes over a hundred years, which is minuscule compared to that age of the earth (4.5 billion years).
Because of its weight, the solid mass of ice is so heavy that it begins to move. Moreover, the glacier exerts pressure on the underlying firn and snow due to its weight, which eventually melts without any temperature change.
In the case of alpine glaciers, gravity plays an important role. However, some glaciers do not flow down the entire length of the mountain. Instead, the ice falls from the hanging glaciers to the larger collection of ice in the valley below. Avalanches and ice falls are common occurrences for alpine glaciers.
On the other hand, the ice sheet spreads out differently. The giant mass of ice spreads in all directions and covers everything that comes in its path. However, the speed at which the glacier spreads varies because different parts move at different speeds. And it is because of the difference between the speeds at which the glacier spreads, there is tension within the upper part of the ice mass and consequently, you find cracks known as crevasses on top of the glacier.
Crevasses can be particularly dangerous for mountaineers as they can open up and be quite deep. Another formation that you can find within a glacier is a deep, almost vertical pipeline known as moulins. They are formed due to meltwater on top of the glacier and are often much deeper, and go all the way down to the bottom of the glacier.
Given that glaciers are a heavy mass of ice, they move due to their weight. Most glaciers move slowly, but some can move as much as 160 feet a day. These fast-moving glaciers are known as galloping glaciers.
When the glacier meets the coast, it is known as a tidewater glacier. Due to constant interaction with water, the edges of the giant ice glacier break into the water, and this process is known as calving. The large chunks of ice that break as a result of calving are known as icebergs.
Zone of Accumulation
The area in which glacial ice forms is known as the zone of accumulation. In this region, more snow accumulates every winter compared to the snow that melts away during summer. The snow that is buried inside turns into firn and eventually crystallizes into glacial ice. Once glacial ice is formed, it flows away from the zone of accumulation under its weight. In the case of alpine glaciers, the glacial ice flows downwards, but in the case of ice sheets, there is a lateral flow of accumulated ice.
On the other hand, there is a zone of wastage. It is the glacier area that experiences more glacial ice melting than the formation of new ice.
The line that separates the zone of an accumulation from the zone of separation is the snow line, which may be visible at the end of the summer season.
The Impact of Climate Change on Glaciers
The formation of glaciers is a long process. It takes more than a hundred years to accumulate enough snow that it converts into glacial ice. However, uncontrolled human activities, including greenhouse gas production, contribute to an overall increase in the global temperature. And, of course, it will eventually have an impact on glacial ice.
According to scientists, glacial ice is melting at a much higher rate than ever before. And studies claim the change will be much more drastic in the next thirty years. Alpine glaciers are under the most threat to global climate change. In addition, the ice sheets are also melting, contributing to an overall increase in global sea levels.
One of the key concerns associated with the melting of glacial ice is that glaciers are a source of fresh water. But once it melts and becomes part of the ocean, it no longer remains as a water source. Hence, with melting glaciers, the concern is not just about the rising sea levels, but there can be other consequences as well as in the future.