Glaciers

Author: Aatmesh. Learner at the Integral School, Hyderabad.

A self directed project that looks at glaciers in the current context of global warming and environmental health.

Glaciers are defined as “Slow moving masses or rivers of ice formed by the accumulation and compaction of snow or ice.” Glaciers are found in regions that receive consistent snowfall, like the poles or the Himalayas. They are formed in extremely cold temperatures, when layers of snow condense and cool, forming sheets of ice.This process keeps occurring with falling snow forming new layers on top of previous ones. This is known as the process of accumulation. Once enough mass has been accumulated, (it usually takes the span of two winters) a glacier is formed. Glaciers often have layers that are comprised of dense ice, but occasionally rocks or sediment that happen to fall onto the glacier get incorporated into its body. Sometimes there are even thin layers of sediment in glaciers.

Glaciers take years to amass, and even then they keep growing. Some glaciers are over 20 million years old and are still moving and growing. Once a glacier reaches a certain mass, the layers furthest from the surface are placed under a great amounts of pressure. This pressure causes cracks in the dense ice and allows water to trickle down to the surface of the earth (upon which the glacier is). This allows less friction between the ground and the glacier, causing better movement. Their movement is the result of gravitational force. The force of gravity is greater on heavier objects, glaciers are extremely heavy and are easily susceptible to gravity. Once a glacier moves down a slope or hill, its giant mass slowly gets pulled toward any other depression or dip in the landscape and proceeds onwards. Most glaciers (ones with enough mass) tend not to stop once their movement has kicked off. Since glaciers are normally located higher up (in montane regions, high above sea level), their downward flow follows a route down the mountains, toward the sea or flatter lands. The movement of glaciers also depends on the season and climate. In winter, most glaciers advance only to retreat in the summer.

Phases of glaciers:

Glaciers are balanced by their different phases of retreating and advancing. Each phase serves as a counterbalance for the life of a glacier. An excess or scarcity of either one would result in extremes (explored in section “Glaciers and global warming”). Both the retreat and advance are with regard to the “terminus” or “snout” of a glacier, also known as the end point. The advance occurs when the glacier has a steady flow of snow and ice. During the advance the glacier’s mass increases exponentially, driving the entire body forward. Once the glacier is motion, it begins to make its way down or through the neighbouring terrain. For the glacier to have a steady movement, the amount of snow that the glacier receives, must far outweigh the rate of its depletion. If that is achieved, then the glacier is on the advance. While on the advance, the glacier moves at its fastest with little to no retreat. The retreat begins when warmer weather melts or erodes the glacier at a faster pace than it is moving forward. In essence, the retreat drives the glacier back. Through the process of melting, much of the glaciers mass turns to water and is evaporated or escapes as a river, stream. Through these phases the glacier moves differently, affecting its environment significantly, depending on its type.

Types of glaciers:

Glaciers can be classified into different types, based on the region they occupy, their movement and more. All glaciers have the same base components, or requirements. The three main components in a glacier are the bedrock, or ground upon which the glacier lays, the layers of ice, or the main body of the glacier and the layer of fresh snow that is falling on top of the main body. To be a glaciers all three of the above requirements must be fulfilled. If all those requirements are fulfilled, we come to the types of glaciers. There are a few different types of glaciers, Alpine glaciers, Tidewater glaciers, Piedmont glaciers, Cirque glaciers, Rock glaciers and a few more.

Alpine or mountain glaciers, are glaciers that are formed at high altitudes. They are formed on mountain peaks or somewhere along the body (of mountains). Alpine glaciers are the most common kind of glacier and exist almost all over the world. When Alpine glaciers increase in size and mass, they begin moving down the mountains. If the Alpine glacier happens to move down into a valley it is called a Tidewater or valley glaciers. Most Alpine glaciers become Tidewater glaciers. Tidewater (‘Tidewater’ because they meet the sea associated with water and tide) glaciers are specifically glaciers that move through and along valleys and head toward the sea. Tidewater glaciers often move along the routes of ancient rivers (through the valley) and shape the valley for rivers that are yet to form. Since Tidewater glaciers travel in between mountain, the sides of the glacier move alongside the mountains, slower than the center. This happens because the sides of the glaciers meet resistance with the mountain whereas the center does not.

When Tidewater glaciers meet the sea, chunks of the glacier break up into icebergs which float. Icebergs float (on water) because they are less dense than water. The process of a glacier meeting the sea and forming icebergs is known as calving. Tidewater glaciers are not the only glaciers which meet the sea and form icebergs, the term ‘calving’ is used with regard to all glaciers. Piedmont glaciers also do the same.

Piedmont glaciers are Tidewater glaciers that spread out over a large expanse of land. When a (Tidewater) glacier crosses a valley and heads into a plane, it spread out in all directions. The glacier is not being directed in only one direction (since it crossed the valley), causing it to spread over the entire surface. This is a piedmont glacier. ‘Piedmont’ is defined as a gentle slope leading from the base of mountains to a region of flat land, hence the name of the glacier.Piedmont glaciers also head towards the sea and are a variation of Tidewater glaciers.

Cirque glaciers are similar to Piedmont glaciers, in the sense that they are sometimes wider in width than in length and they spread out. When an Alpine glacier moves into a hollow bowl shaped area, it becomes a cirque glaciers. The depression in the land where cirque glaciers form is called a ‘cirque’ hence the name.

Rock glaciers are glaciers that are comprised of ice, mud, debris and rock. In these glaciers, the ice is at the bottom and is covered by rocky debris on top. The glacier appears to be a moving mass of rock and mud, but that is just the outer visible layer. The movement is initiated by the ice layer and the body follows suit. Rock glaciers look the queerest out of all the glacier types and are often formed when a Cirque glacier flows out of its cirque, along with mud and rock. There are a few other classifications of glaciers, but the most common are the ones above.

Geographical effects of glaciers:

When glaciers move about in a certain area, they mould the environment. Glaciers are very powerful, they can clear anything in their path. Once a glacier has passed over an area, it (the area) is often barren but clean. When sediment and rocks are incorporated into glaciers, they are frozen and move with the glacier. Throughout their movement, the rock and sediment come into contact with the surface below the glacier (a process called abrasion). This leaves the land below the glacier with scratch marks from abrasion.

Another thing that glaciers do is transport rocks and minerals. The rocks and mineral in the glacier move with it. If the glacier melts, the debris and rock are defrozen and have been transported from one place to another. Glaciers also push debris (with their snouts) forward. When glaciers rub against mountains, they cause erosion (wherever they come in contact with the mountain) and transport the eroded debris wherever they go also effectively moving it. When glaciers transport large amounts of debris and drop them off, they can form hills or small land masses. These masses are made up of till or glacial debris.

Glaciers follow the path of least resistance. Sometimes, when glaciers flow down into valleys they break off into tributaries. This happens when a large amount of resistance is in its path. If a huge boulder lies in the middle of a glacier’s path, it will move around the boulder, splitting into two. If something similar occurs with more than one object blocking the glacier’s path, each tributary goes down its respective path of least resistance branching out and not joining back into one solid body. This forms tributary glacier that move independently but have the same source. Glaciers also create ‘U’ shaped valleys, cirques and even fjords. They are also the source for many rivers. They influence many landforms and the geography of the world heavily.

Glaciers and global warming:

Glaciers make up a considerable amount of our planet and have major effects on it. The balance between retreat and advance is marvellous to see. Nature almost always has counter balances and checks in place, and glaciers survive due to this natural balance. Unfortunately, in recent years more of one phase has been going on. Glaciers have been predominantly retreating. The cause of their retreat is global warming. Global warming is a phenomenon in which gases in the Earth’s atmosphere capture excessive heat, which results in higher temperatures. With the overall world temperature increasing, the amount of snow that most glaciers receive cannot match the depletion rate, resulting in the retreat and disappearance of glaciers worldwide.

The excessive melting of glaciers causes many problems for the world. Firstly, the water produced by the glaciers increases the sea levels drastically. Increases in sea level (of this magnitude) result in the destruction of habitats (for all organisms), floods, contamination of agricultural soil and the submersion of islands. Also, the freshwater or meltwater from them (glaciers) can sometimes kill plankton because it disrupts the salinity in the water. This would cripple the oceanic food chain and much of the world. The melting of glaciers would also increase global warming, because glaciers reflect more heat back out to space than water does.

Without glaciers, there may not be any more ciques, fjords and other such unique landforms, excessive retreating is the problem, but excessive advance can be equally devastating because if glaciers advanced too much, there would be fewer rivers and less drinking water but lower sea levels. It would be the opposite of what is occurring now.

With all the evidence, there are two trains of thought with regard to the excessive melting of glaciers. One train of suggests that if the natural balance of the glacial phases is disrupted, it would affect other phenomena (sea levels etc.). This would destroy the world and leave it uninhabitable for humans in the future. Although humans don’t have the ability to control natural powers like glaciers, any small acts (cutting down carbon dioxide emissions etc.) can help return balance to glaciers and save them from extinction. Reducing global warming will save the glaciers and world according to this theory.

On the other hand, the scale of glaciers and the world is very large. It may be that there is nothing we can do but bear witness, that we have no say in what will occur (glacial extinction, melting etc.). Something else might replace the glaciers or the world might be moving into a new phase (like from the ice ages to a new age). It may also be that nature has its own balances which we simply cannot see or comprehend, that in the future the Earth will heal itself and that more meddling from humans will only make things worse. This theory is called the Gaia theory. Neither theory can be proved or disproved so far.

Afterword:

Glaciers are interesting and ancient, with the ability to transport rocks and destroy forests. They move along the earth while following the path of least resistance, although they are not sentient. They are complex and occur in many types and their impact on the physical world is widespread and large. Although they may soon disappear from the world, they will most likely be remembered.

 

An essay by Aatmesh.