• Accelerated melting of the Himalayan Parkachik Glacier in Ladakh could give rise to three glacial lakes with an average depth ranging between 34 and 84 metres, scientists have found.

• These lakes could be a potential source of glacial lake outburst floods in the Himalayas, the scientists from the Wadia Institute of Himalayan Geology, Dehradun, said.

• Glacial lakes are formed when a glacier erodes the land and then melts, filling the depression created by the glacier.

• Parkachik Glacier is one of the largest glaciers in the Suru River valley, which is a part of the Southern Zanskar Ranges, western Himalaya. 

• The Zanskar Range, part of the Himalayas, lies in the Union Territory of Ladakh.

• The glacier’s yearly melting rate was six times faster between 1999 and 2021 (22 years) than that calculated from 1971 to 1999 (28 years).

• The scientists found this using satellite data to determine its glacial retreat from 1971-2021. 

• The findings are published in the journal Annals of Glaciology.

• The study attributed the accelerated glacial retreat to ongoing climate warming, which also causes surface morphological or geological changes to glaciers.

• Faster glacial retreat, along with surface morphological changes, have been known to result in the forming of new glacial lakes and expansion of existing ones, a potential source of glacial lake outburst floods.

The dynamics of glaciers

• Glaciers are bodies of moving ice that develop as snow accumulated in cold places compacts and recrystallizes. The formation of a glacier takes decades to millennia, and its size varies depending on the amount of ice it retains throughout its lifespan. 

• Each year, glaciers gain and lose mass. They gain mass from snow and precipitation in their upper portions (accumulation zone) and lose mass in their lower portions (ablation zone) by partially melting in summer. In marine-terminating glaciers, they also lose mass by calving icebergs that float away.

• The balance between accumulation and ablation is the mass balance of the glacier. If accumulation is greater than ablation, then the glacier has a positive mass balance and will advance. If ablation is greater than accumulation, then the glacier has a negative mass balance and will retreat. 

The critical importance of glaciers for sustaining life on Earth

• Covering about 10 per cent of the planet’s surface, ice masses are crucial for sustaining life on Earth.

• Glacial ecosystems provide vital resources to a significant proportion of the global population because of their high biological diversity and ecosystem services such as sediment sinks, freshwater reservoirs and habitats for biodiversity. 

• The benefits include freshwater for domestic use, agriculture, industry and hydropower, as well as climate regulation.

• About 50 per cent of the global biodiversity hotspots on the planet are located in basins drained by glaciers and contain a third of the entire terrestrial species diversity.

• Often referred to as natural “water towers”, glaciers in mountains provide lowlands with essential freshwater supply. 

• The High Mountain ranges of Asia are covered by approximately 100,000 km² of glacier ice and feed the great rivers of Central Asia (Amu Darya and Syr Darya) and South Asia (Brahmaputra, Ganges and Indus), Southeast Asia (Huang He, Mekong and Yangtze). 

• The Antarctic and Greenland ice sheets are the largest bodies of ice in the world and play an important role in the global climate system. They serve as a global thermostat regulating ocean circulation, and their white ice cover cools the atmosphere by reflecting sunlight (albedo effect).

• Glaciers are a sensitive indicator of climate change and one that can be easily observed. Although there are around 200,000 glaciers on the planet, only a few hundred are currently monitored in-situ because they are often difficult to access. Satellite imagery has thus become one of the most valuable methods to keep track of the world’s retreating glaciers.

Manorama Yearbook app is now available on Google Play Store and iOS App Store