Snow-clad mighty mountains and rough terrains dominate our perspective of the Himalayas. What about its glaciers and the fact that they provide headwaters for major river systems in Asia? As the Arctic and the Antarctic glaciers make news for unprecedented melting, is it all well with our own ice mass
Seventy % of the earth’s surface is water. Of the remaining 30%, 20 is land and 10 is ice. Most of the ice is in the Arctic and the Antarctic, and the rest is scattered around the world in the form of mountain glaciers.
The Himalayas contain the third-largest deposit of ice and snow in the world. There are about 15,000 glaciers in the region, including Gangotri and Yamunotri (Uttarakhand), Khumbu glaciers (Mount Everest region), Langtang glacier (Langtang region) and Zemu (Sikkim). These glaciers form the source of perennial rivers across the Indo-Gangetic plains. The Indus, Ganga and Brahmaputra and their tributaries are the lifeline of millions of people in South Asian countries such as Pakistan, Nepal, Bhutan, India and Bangladesh. Did you know that the Gangetic basin alone is home to 500 million people?
The bad news
Just like the glaciers in the polar regions, the Himalayan glaciers are also melting. Studies have found that glaciers in the eastern and central regions of the Himalayas are retreating as fast as the ones in other parts of the world, whereas the western Himalayan glaciers are more stable.
A study published in the journal Nature, last month, predicted significant loss in ice mass in the region. Asia’s mountain glaciers will lose at least a third of their mass through global warming by the century’s end, it said. A scientist at the Indian Institute of Sciences, Bangalore, analysed 146 glaciers spread across the Chandra basin in western Himalayas and found that the glaciers on low altitudes are melting at a faster rate than the ones on higher altitudes. In 2015, a group of international researchers found that Mount Everest region will disappear or drastically retreat due to climate change over the next century.
Why this happens
Experts have held that it is difficult to attribute glacier retreat over the entire range to one specific cause. However, the Intergovernmental Panel on Climate Change suggests global warming as the cause. Deforestation, land-use changes also adversely affect these glaciers, it says. Changes in precipitation and decrease in snowfall could also impact the rate of glacial retreat.
The changes have direct impact on freshwater flow. As millions are dependent on this water source, the effect is multi-dimensional. Drinking water supplies, hydropower, industry, agriculture and biodiversity will all be affected.
Why it matters
Is it not good that we will get more water if glaciers melt? The glaciers will initially provide extra runoff from melting, but as the ice diminishes, the runoff will wane. The current retreat may not cause significant changes in water availability, especially at lower elevations, which depend primarily on monsoon rains. But later, when there is a drought or a monsoon failure in India, for instance, water stored in glacial ice could come handy to meet the needs of the growing population. With the glacier retreat, we could lose this ‘buffer’ in the long run. The region that loses glaciers will be subject to erosion and decreased stability.
When glacial mass melts at a larger scale, they contribute to sea-level rise. Large quantities of fresh water will be added to the ocean every day.
Glacier melting is considered the most sensitive indicator of climate change.
The danger in glacial lakes
The most worrying outcome of glacial recession is the increase in the formation and the size of glacial lakes. They are formed when a glacier erodes the land, and then melts within the hole it created. This in turn could lead to glacial lake outburst floods (GLOF) when there is an avalanche or an earthquake.
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