Glaciers
Glaciers are made up of fallen snow that, over many years, compresses into large, thickened ice masses. Glaciers form when snow remains in one location long enough to transform into ice. What makes glaciers unique is their ability to move. Due to sheer mass, glaciers flow like very slow rivers. Some glaciers are as small as football fields, while others grow to be dozens or even hundreds of kilometers long.
Presently, 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. Most glaciers lie within mountain ranges that show evidence of a much greater extent during the ice ages of the past two million years, and more recent indications of retreat in the past few centuries.
Importance of glaciers
All of the phases of water—solid, liquid and vapor—relate to glacier dynamics. Water has unique qualities that come into play in understanding the roles glaciers play in the Earth system. For example, water expands rapidly when it freezes—an increase of about 9% by volume. Also, water enters the atmosphere through the familiar cycle of melting and evaporation, but water can also enter the atmosphere directly from a solid state through a process known as sublimation. Also, water—the only substance that is lighter in its solid (ice) than its liquid state—has more density as salt water than as fresh water.
The melting fresh water from glaciers alters the ocean, not only by directly contributing to the global sea level rise, but also because it pushes down the heavier salt water, thereby changing what scientists call the THC, or Thermo (heat) Haline (salt) Circulation, meaning currents in the ocean. This has an immediate effect on the near region, such as the north Atlantic off the coast of Greenland, but ultimately the impacts can ripple far beyond the immediate area and climate.
Ice that took centuries to develop can vanish in just a few years. A glacier doesn’t melt slowly and steadily like an ice cube on a table. Once glacial ice begins to break down, the interaction of meltwater 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.
Water not only expands when frozen, but also when heated, and it is estimated that in the 21st century the melting of ice caps and glaciers combined with the thermal expansion of ocean water will cause an average increase of sea level of roughly a meter (a bit more than one yard). That’s an average; in some places it will rise more and in others less, in part because (as we now know through satellite measurements) sea level itself varies, bulging in some places and slumping in others. In Greenland, for example, it is expected that as the ice melts into the ocean the land mass will rebound, in effect “bouncing back” after it was pushed down by the weight of the ice. Sea levels may actually go down in some regions, but rising sea levels will be a critical issue in many other parts of the planet, adversely affecting billions of people in India, Bangladesh and China as well as along the U.S. Gulf and Northwest coasts.
As the planet’s air conditioner, the polar ice caps impact weather and climate dynamics, such as the jet stream. Glaciers are also early indicators of climate changes that will have a somewhat more delayed impact on other parts of the Earth system. 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. Our way of life is based on climate as we know it.
Important glaciers of india
Gangotri
Gangotri Glacier is the Himalayan glacier situated in the Uttarkashi district in the Indian state of Uttaranchal. It is the largest glacier in the Garhwal Himalayas.
Pindari
Pindari glacier falls in the Kumaon Himalayan Mountain range at an altitude of 3353 meters. The Glacier is is 3 km in length and 0.25 km in breadth. The Pindari river originates from this glacier.
Milam
Milam is one of the largest and major Glacier in the Kumaon region. It is locatedet in the Pithoragarh district of Uttarakhand, India, at the height of 4250 meters above the sea level.
Nanda Devi
Nanda Devi, which means ‘blessed Goddess’ is the highest mountain in India. Nanda Devi holds the the spectacular wildlife, carefully preserved in the Nanda Devi National Park.
Siachen
The Siachen Glacier is located in the extreme north central part of Jammu and Kashmir near the Indo – Tibet border. It is the largest glacier in the world outside the Polar regions. It originates from the Sia Kangri in the Karakoram range and is approximately 72 km in length. It lies in the Karakoram range of mountains at the altitude of 5, 400 meters above the sea level. Just like the other glaciers, Siachen glacier has a vast snow field in the center. It can easily be approached via Skardu in Ladakh. The glaciers melting water is the main source of water for the Nubra river, which further falls into the Shyok River.
Satopanth Glacier
Satopanth Glacier is situated in Chamoli district of Uttarakhand. Deriving its name from two words, Sat-o- meaning truth and Panth meaning way or path, this glacier is a divine destination for avid trekkers and adventure enthusiasts. Located amidst the nature’s lap, the glacier is fed by the ice found on the eastern slopes of Chaukhamba group of peaks.
Zemu Glacier
Zemu Glacier is a 26 km long glacier draining the east side of Kanchenjunga the world’s third highest mountain. The importance of the glacier is that it is a key water source for the Teetsa River. The glacier acts as a natural reservoir releasing water due to melting. The Teetsa River is the focus of a hydropower development project being undertaken by the Government of Sikkim.