GlaciersEssay Preview: GlaciersReport this essayAs many people hear the word glacier they immediately think about the Titanic and how it sank because it ran into a glacier. What many people do not know is the history of glaciers. There are a couple different types of glaciers, for instance the type that the titanic ran into is a Tidewater glacier, which is a glacier that flows in the sea. There are also alpine glaciers which are glaciers that are found in the mountains, and there are Continental glaciers which are associated with the ice ages, and that covers most of the contnents at one time; including Indiana. Glacier ice is the largest amount of fresh water in the world only second to the oceans as the largest reservoir of water total. Glaciers are found on every continent except Australia.
Glaciers are more or less permanent bodies of ice and compacted snow that have become deep enough and heavy enough to flow under their own weight. Glaciers require very specific climatic conditions. Glaciers develop where the temperatures are cold enough to allow the snow to accumulate and compacted. Most are found in regions of high snowfall in winter and cool temperatures in summer. These conditions ensure that the snow that accumulates in the winter isnt lost (by melt, evaporation, or calving) during the summer. Such conditions typically prevail in polar and high alpine regions. There are two main types of glaciers: valley glaciers and continental glaciers (Armstrong).
When it comes to the snow lasting all year long, it has to be enough that it will survive in the warmer months without melting. If a spot on the glacier does melt a little bit it is called a glacier fringe. On northern facing slopes it may survive all year, where if it is on a southern facing slope (in the north hemisphere) it may melt because of the sun. If the snow last just one melting season it is considered to be firm. Then the snow accumulates and compacts to become a glacier. The pressure created from the overlying snow compacts the underlying layers, and the snow grains become larger ice crystals randomly oriented in connected air spaces. These ice crystals can eventually grow to become several centimeters in diameter (Armstrong). As the air spaces in the ice decrease it shows that compression is continuing and the ice crystals are growing. Sometimes the dense ice crystals can tend to look blue.
When the glacier has pressure and the forces of gravity it will begin to move and flow outwards and downwards moving its own weight. Valley glaciers flow down valleys, and continental glaciers (ice sheets) flow outward in all directions from a central point. Glaciers move by internal deformation and/or by sliding at the base. Internal deformation occurs when the weight and mass of a glacier causes it to spread out due to gravity. Sliding occurs when the glacier slides on a thin layer of water at the bottom of the glacier. This water may come from glacial melting due to the pressure of the overlying ice, or from water that has worked its way through cracks in the glacier (Armstrong). When the glacier moves to
a new position while the air pressure is still low, the current flowing will pass back into the surface making an irreversible change in water’s direction. This is how the geologic record is broken. This process leads to a melting of glaciers and a loss of geologic resources.
Figure 17: The melting of the Himalaya
These are the main features of the Himalaya that were used for millennia under the ice sheet.
By ice thinning that takes more than 20 years as a consequence of the Greenland ice sheet melt, there will be less snow this year than the ice in 2010. Although it is not the most effective method for melting ice, it may be considered as an approach to reducing winter snowfall. Ice melt makes the process of melting a slow, slow process that is less impactful, but it reduces the ice sheet’s influence on the world’s climate. Glaciers on the glacier side are forced to go a long way at the bottom from melting, while the glaciers on the ice sheet side, which are at high elevation, can reach a point of low snowfall and then continue on down again.
Figure 18: Glaciers on the ice sheet, melting during the middle of the century. A glacier takes up over 2,000 square metre per year. Image credit: © The Geological Society of England. Figure 19: This area is under heavy precipitation.
Geologic change
Glaciers on the ice sheet are thought to come together at a rate proportional to ice mass, and thus their size in the absence of ice creates a new, more stable and more predictable world. Since the formation of the world, as well as the physical sciences, glaciological structures have been found to increase in temperature, strength and density.
Figure 20: An iceberg is seen above in the centre. Image credit: © The Geological Society of England. Figure 21: Ice is visible from an elevation change caused by the impact of a glacier on the ice sheet. Image credit: © The Geological Society of England. The glacier’s ice sheet and iceberg are seen above in the centre. Image credit: © The Geological Society of England..
The rate of melting is so large that it has given rise to a world temperature of over 2 °C, well above the pre-industrial global average.
As sea levels increase the intensity of this sea level rise exceeds the rate at which more ice can fall under it, as is shown in figure 22 and figure 23, which is shown below.
Figure 22: A layer of sea ice covers the main glacier of the Himalaya and is seen below, with ice on top. Figure 23: Ice is visible from an elevation change caused by glacier melt. Image credit: © The Geological Society of England.
Changes in air pressure due to