A glacier is a huge block of solid ice that is formed over the years, by falling snow. Their size can vary vastly from a few hundred meters, to a few thousand meters in length (the Lambert glacier located in Antarctica is the largest one on earth and is approximately 40 miles wide and 440 miles long).
Even though a glacier is solid ice, it is constantly moving, though very slowly. It could move from a few inches to a few feet a day.
Glaciers are formed in locations, where it snows and the temperatures are low enough not to allow all the fallen snow to melt. When a fresh layer of snow falls, the previous layer gets compressed. This cycle continues until the lower layers of snow get compressed enough to turn into solid ice. Their formation is not possible in areas where it snows, and a change in season sees the temperature rise enough, to liquefy all the fallen snow. The amount of snow liquefying, must be less than the amount of snow that has fallen - only then will it get converted into a glacier, over a long period of time.
The melting of glaciers is a normal and natural process. Every single one melts, the level of liquefying depending on the surrounding temperature. In most places containing them across the globe, snow falls during the cold seasons and will get compressed into ice with further snowing. When the temperature does get a bit warmer, the upper fresh layers of snow / partly formed ice, begin liquefying and flowing down into streams and rivers. Many places on earth depend on this melted freshwater for survival. The liquefied snow provides fresh and pure drinking water, water for agriculture, and in many nations this flow of water is converted into electricity, without polluting the atmosphere.
Melting Faster Today
It is normal for glaciers to liquefy and get replaced by more snow than the snow that has liquefied. In the past century, this trend has changed world-over. They are melting faster than the snow replacing it, causing them to shrink in size, year after year. There are many causes for this; but the main cause is said to be 'global warming'.
Also known as 'climate change', global warming is the increase in average temperatures worldwide. Over the past century, the average worldwide temperature has risen by half a degree Celsius. This might seem very miniscule, but this slight change has already caused tremendous harm and damage all across the globe.
Rapid industrialization in the past century is the culprit. We have, in the past 100 years, burnt more fossil fuels than ever before. Fumes from automobiles and the indiscriminate burning of coal, have all increased the levels of greenhouse gases, which in turn trap more heat into the earth's atmosphere, thus raising average global temperatures.
Why are Glaciers Melting Faster Today?
With an increase in global temperatures, glacier ice is melting faster. Almost everywhere, fresh snow can not replace the amount of the liquefied ice. This is leading to glaciers reducing in size. Many of them, that existed even a hundred years ago, are gone -- forever. If the current trend of global warming continues, many more will be gone forever, within a few decades.
The disappearance of glaciers has lots of bad effects, many of which are already beginning to surface. With a temperature rise, the sea water has heated up, and sea water levels have risen. Melting glaciers (land based) are emptying into the sea, further increasing sea water levels. This will have a direct impact on those living in low lying coastal areas.
Glaciers absorb a little heat, reflecting most of the heat back into space. When it has liquefied totally, the Earth below is exposed. The Earth will now absorb most of the heat, reflecting back just a small amount. This will cause the Earth to heat further. This increased heat will cause the remaining glaciers to melt faster. This is a vicious cycle that is happening right now.
Help Reduce Global Warming
The blame for glaciers melting faster today, lies entirely on us. We have caused a situation where the earth is heating up more than required, and they are melting away into memories. Many on the planet, are already feeling the horrible effects of this. If we do not take immediate steps to help reduce global warming, many more will suffer in the years to come.