Ecology And Environment

How Glaciers Form



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Few people realize how important glaciers are to the planet. They may not understand exactly what glaciers are or how they form. Glaciers are essentially huge masses of ice, on land or floating on the sea near to land. Glaciers are not static but they move very slowly. They may merge with other glaciers and become huge ice rivers.


Glaciers form in places where there is continuous snowfall and constantly cold temperatures. Enough snow must fall each winter to ensure that it never all melts in summer. Usually in places with cold, snowy winters and cool summers. Not all cold areas have glaciers, because they are too dry and do not receive enough snow to replace the melting caused by warm spells and wind erosion.

Permanent ice is very common in mountainous areas close to the Polar Regions because the sun’s rays less direct the further one gets from the Equator and in the high mountains because air-cools as it rises.


Valley glaciers only form above the snow line, the lowest level where snow lays all year round. Most glaciers form in the high mountains such as the Himalaya, and the European Alps, the Andes, Sierra Nevada and Mount Kilimanjaro, which have regular snow and very cold temperatures all year.


In Alpine areas usually form on the side of the mountain most exposed to the wind. Moisture bearing winds rising to get over the mountains cool and the moisture falls as heavy snow. Antarctica only gets a few inches of snow per year but stays ice covered because it is constantly so cold that the snow almost never melts. Once snow builds up, the loosely packed snowflakes compact into thin bands into thin bands of glacial ice. The snow’s weight further pressing on the snow beneath it, and the ice bands slowly develop into glaciers. When the edges of the glacier begin to melt, it starts moving, flowing down the valley. Over thousands of years, glaciers have carved out mountain valleys and although there may be no glaciers in these places today, such as in areas of France, one can see which valleys glaciers carved and which were formed by water, simply by their distinctive shape. Glaciers near to the Equator are short, perhaps only two, or three kilometers, however, further from the Equator, glaciers can be huge, the largest in the World is the Lambert glacier in Antarctica at 435 miles long. Switzerland’s Alethsch Glacier is 14.3 miles long, but Austria’s largest Glacier is a mere baby at 5 miles.


Glaciers are, of course found also in the World’s cold regions Greenland, Antarctica, Iceland, Canada, and Alaska. A Glacier, which forms on a high mountain plateau and moves in all directions, is usually called an ice cap and when these grow to cover islands or continents they are ice sheets. Currently the World has two big ice sheets. In these places, the ice can be 2 miles thick, but ice caps and ice sheets are still essentially glaciers. When ice sheets extend over the sea huge pieces of ice break off and float away becoming icebergs. These are a shipping hazard; an iceberg sank The Titanic.


Snowflakes falling in such regions do not melt, but combine with other snowflakes, forming ice grains, which get larger as more and more snow layers press down upon them. Air pockets between the crystals reduce in size as the weight of snow compresses the lower layers. After approximately two years, the snow reaches a stage mid-way between snow and glacier ice, called firn. The ice crystals keep growing and as further snow falls, the air bubbles become smaller and smaller and eventually are forced out by increasing pressure, a glacier appears. In glaciers over a hundred years old, ice crystals can reach several inches long. When the weight of snow layers has pressed nearly all the air out of the ice the glacier looks blue. Snow at the top of the glacier is rather brittle and prone to cracking but its lower layers are flexible due to the enormous pressures above. This difference causes crevasses in the glacier’s top layers, often hidden under fresh snow.


Glaciers pick up stones and boulders as they move and these are carried along by the Ice Rivers. When glacial ice is too thick to resist gravity it begins to move downhill. How fast a glacier moves depends on the slope’s gradient.


Victorian scientists began learning about how the Earth’s climate functions and changes. Modern scientists, building on that knowledge, have learned much about Earth’s climate history and, by using this history, how to predict how the climate might be in the future. Scientists know that there have been at least four ice ages. After each one, there has been a warmer period, causing glaciers to retreat. The last Ice Age ended around 10,000 years ago although there was a cold period between 1550 and 1850AD, which is often mistakenly called The Little Ice Age. It was not truly an Ice Age in the conventional sense because although cold weather was quite severe in some areas, it did not affect either the whole Earth or one complete hemisphere. The Earth is currently in a warming phase.


Warm periods are a natural feature of the Earth’s climatic cycle and many people point to this fact and use it to deny human made climate change. However, the problem with their analysis is that since the Industrial Revolution, warming is happening much faster than it could possibly do naturally. Plants and animals evolve and slowly adapt to natural warming and the changing of conditions and habitat that warming causes. Human made warming is happening too fast to allow life to adapt.


During warming cycles glaciers melt. Glaciers hold most of Earth’s fresh water. When warming happens faster than it would naturally do, glaciers melt at a faster than normal rate. More fresh water is in the system, rather than being locked in glaciers. Fresh water flows into the sea raising sea levels and lowering salinity levels in the oceans and the oceans’ abilities to reflect sunlight thus leading to more warming. Glaciers, which melt too fast can mean drought in some areas and flooding in others, they can mean dramatic changes in the World’s weather and landscape. Natural slow cycles give plants, animals, and the land itself time to adapt. Warming exacerbated by man’s activities does not and results not in plants and animals adapting and a few, who cannot adapt going extinct, but in large-scale extinctions. 


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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://ga.water.usgs.gov/edu/watercycleice.html
  • InfoBoxCallToAction ActionArrowhttp://www.climate.org/topics/sea-level/index.html
  • InfoBoxCallToAction ActionArrowhttp://www.english-online.at/geography/glaciers/glaciers.htm
  • InfoBoxCallToAction ActionArrowhttp://what-when-how.com/water-science/glaciers-water-science/