Pensilungpa Glacier retreat due to warming

Context:

A recent study has found that the Pensilungpa Glacier located in Ladakh’s Zanskar Valley is retreating due to increase in temperature and decrease in precipitation during winters.

Relevance:

GS-I: Geography (Physical Geography, Distribution of Key Natural Resources, Water Resources, Important Geophysical Phenomena), GS-III: Environment and Ecology (Climate change and its impact)

Dimensions of the Article:

1. What is a Glacier?
2. What does “Glacier Retreating” mean?
3. About the Study on retreating Glacier in Zanskar Valley
4. About Zanskar Valley
5. Important Glaciers in India

What is a Glacier?

• A glacier is a persistent body of dense ice that is constantly moving under its own weight. It is form by the accumulation of snow exceeds its ablation (melting and sublimation) over many years. It is the largest reservoir of fresh water on the Earth (75 percent of the world’s fresh water).
• Glaciers are unique because they are reservoir of fresh water, have sheer mass and their ability to move (Glaciers flow like very slow rivers). It may move in two ways- Internal flow is when the pressure and gravity on the ice in a glacier cause it to move downhill; Basal sliding is when an entire glacier moves because its base is slightly melted. Rivers, valleys and lakes are formed after melting of glaciers.
• As per National Snow & Ice Date Centre, it occupies about 10 percent of the world’s total area.

What are Glacial lakes?

• A glacial lake is a body of water with origins from glacier activity.
• They are formed when a glacier erodes the land, and then melts, filling the depression created by the glacier.

How are glaciers and glacial lakes formed?

• Glaciers are found on every continent except Australia and some are hundreds of thousands of years old; and a large cluster of glaciers are in the Himalayas.
• Glaciers are made of layers of compressed snow that move or “flow” due to gravity and the softness of ice relative to rock.
• A glacier’s “tongue” can extend hundreds of kilometers from its high-altitude origins, and the end, or “snout,” can advance or retreat based on snow accumulating or melting.
• Proglacial lakes, formed after glaciers retreat, are often bound by sediment and boulder formations.
• Additional water or pressure, or structural weakness, can cause both natural and manmade dams to burst, sending a mass of floodwater surging down the rivers and streams fed by the glacier.

What does “Glacier Retreating” mean?

• A glacier retreats when its terminus does not extend as far downvalley as it previously did.
• Glaciers may retreat when their ice melts or ablates more quickly than snowfall can accumulate and form new glacial ice. Higher temperatures and less snowfall have been causing many glaciers around the world to retreat recently.
• Glacial retreat leaves boulders and masses of scraped-together rocky debris and soil called glacial moraines. Large temporary lakes of glacial meltwater may rupture, causing catastrophic floods and even shifting global climate by dumping freshwater into the oceans and so altering their circulation.

About the Study on retreating Glacier in Zanskar Valley

• Observations for four years (2015–2019) showed that the Pensilungpa Glacier is now retreating at an average rate of around 6 metre per annum. This is attributed to an increase in the temperature and decrease in precipitation during winters.
• The study also points at the significant influence of debris cover on the mass balance and retreat of the glacier’s endpoint, especially in summer.
• The study also suggests that due to continuous rise in the air temperature in line with the global trend, the melting would increase, and it is possible that the precipitation of summer periods at higher altitudes will change from snow to rain, and that may influence the summer and winter pattern.

About Zanskar Valley

• Zanskar Valley is a semi-arid region nestled in the northern flank of the Great Himalayas at an altitude of more than 13 thousand feet.
• The Zanskar Range is a mountain range in the union territory of Ladakh that separates Zanskar from Ladakh and the average height of the Zanskar Range is about 6,000 m.
• This mountain range acts as a climatic barrier protecting Ladakh and Zanskar from most of the monsoon, resulting in a pleasantly warm and dry climate in the summer.
• Marbal Pass, Zojila Pass in the extreme northwest of Zanskar range are two notable passes in the region.
• Many rivers start in different branches of this range flow northward, and join the great Indus River. These rivers include Hanle River, Khurna River, Zanskar River, Suru River (Indus), and Shingo River.
• The Zanskar river then takes a north-eastern course until it joins the Indus in Ladakh.

Important Glaciers in India

-Source: The Hindu