Glacier is a mass of ice formed from compacted snow that is thick enough to flow plastically. Glaciers occupy about 10 percent of the world’s total land area,
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| What are glaciers? | Glacier is a mass of ice formed from compacted snow that is thick enough to flow plastically. Glaciers occupy about 10 percent of the world’s total land area, with most located in Polar Regions like Antarctica, Greenland, and the Canadian Arctic. Glaciers can be thought of as remnants from the last Ice Age, when ice covered nearly 32 percent of the land, and 30 percent of the oceans. Warmer temperatures cause glaciers to melt faster than they can accumulate new snow. |
| Why glaciers are melting? | The era of industrialization, particularly in the past 50 years has led and impacted climate change.Gases such as carbon dioxide, methane and nitrous oxide which have been circulating for a long time in the atmosphere have increased as a result of human activities.
The increase in carbon dioxide is primarily due to the excessive use of fossil fuel and changes in land-use. Short lived pollutants like ozone and black carbon, have also shown an increase in their levels adding to the warming. These gases absorb the heat radiated from the surface of the earth, and warms up the atmosphere. Apart from gases, tiny articles in the atmosphere like aerosols, can also lead to the warming of atmosphere. One such kind of aerosols is “black carbon”. Investigations have revealed that deposits of aerosol black carbon on glaciers has led to greater absorption of solar radiation causing glaciers to melt faster. A good example of this is the Himalayan region. Glaciers are sentinels of climate change. They are the most visible evidence of global warming today. In addition to raising sea water levels, widespread loss of glaciers will likely alter climate patterns in other, complex ways. For example, glaciers’ white surfaces reflect the sun’s rays, helping to keep our current climate mild. When glaciers melt, darker exposed surfaces absorb and release heat, raising temperatures.
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| What are the global threats due to melting of glaciers? | Once glacial ice begins to break down, the interaction of melt water and sea water with the glacier’s structure can cause increasingly fast melting and retreat. Today, Earth’s surface is made up of 71% water, 10% ice and 19% land. Most of the world’s ice is in the Arctic and Antarctic, but some of it is scattered around Earth in the form of mountain glaciers. World sea-level is expected to rise 60cm to 70cm by 2100 but this is mostly due to thermal expansion (as the sea gets warmer, it expands). Significant glacier melting in Artic, Antarctic, Himalayan and Alpine regions could produce another meter of sea-level rise by around 2200.
Thus low lying places and poor people are more vulnerable to the effects of sea level rise than higher altitude places and richer people. Sea level rises are more likely to cause mass migrations than mass mortality. Examples: Most of the tiny islands that make up the Maldives are less than two metres above sea level. The 300,000 people that live there may soon become climate change refugees. In 2008, the Maldives President asked neighbours India and Sri Lanka if he could buy some of their land. |
| Glacier melting and its impact on India | Running 2,000 kilometres from east to west and comprising more than 60,000 square kilometres of ice, the Hindu Kush–Karakoram–Himalayan glaciers are a source of water for the quarter of the global population that lives in south Asia. These natural stores and regulators of water supply to rivers, which, in turn, provide water for domestic and industrial consumption, energy generation and irrigation.
In case of India if the earth keeps warming at the current rate, Himalayan glaciers are likely to disappear altogether in 25 years. In the absence of glaciers, rivers in the Indo-Gangetic plain will become much more seasonal, threatening the rabi crop as well as domestic and industrial water supplies in the non-monsoon months. In addition, more precipitation will fall as rain rather than snow and the greater water run-offs will increase flooding. Up to half of the glacier decline is thought to have occurred as a result of upper atmospheric heating from the black carbon particles in the south Asian brown cloud. In addition, deposits of these soot particles in snow and ice accelerates melting. Further the frequency of tropical cyclones is predicted to increase as a result of global warming. Because rain, rather than snow, falls on mountains in spring, river flows will peak before the main growing season. Summers will increasingly see dry streams, withered and abandoned crops, dead fish and low groundwater levels. |
