Climate Change may lead to decreased water flow in Himalayan Glaciers

By Vivek Saini

The UN Secretary-General Antonio Guterres has issued a warning that crucial Himalayan rivers like the Indus, Ganges, and Brahmaputra, which are all vital to India, may experience decreased flows as glaciers and ice sheets retreat in the coming decades as a result of climate change. Guterres spoke at a concurrent conference with the UN Decade for Action on Water and Sanitation (2018-2028). The event-Midterm Comprehensive Assessment of Implementation of the UN Decade for Action on Water and Sanitation (2023) Conference, was co-hosted at the UN Headquarters by Tajikistan and the Netherlands recently.

How are the glaciers across the world faring?

According to a UN assessment, a third of the glaciers on the UNESCO World Heritage list are currently in danger. These glaciers have been shrinking at an accelerated rate since 2000 as a result of CO2 emissions, which are increasing temperatures, according to a study presented at the 27th United Nations Climate Change Conference in Sharm El Sheik, Egypt, by UNESCO. They currently account for about 5% of the observed global sea-level rise and lose 58 billion tonnes of ice annually, equal to France and Spain’s annual water use.

The study did note that it was still possible to salvage the other two-thirds. If the increase in world temperatures compared to the pre-industrial era was limited to 1.5 degrees Celsius, then this would be feasible. 

Why are glaciers important to human life?

Glaciers are a major source of water supply for home consumption, agriculture, and power for half of humanity. A significant source of biodiversity, glaciers support numerous habitats. Every continent, except Australia, has glaciers. They are thousands of years old for the most part. Because of gravity and the relative softness of ice to rock, they are composed of layers of compressed snow that “flow” or move. “When glaciers melt rapidly, millions of people face water scarcity and the increased risk of natural disasters such as flooding, and millions more may be displaced by the resulting rise in sea levels,” IUCN Director General Dr Bruno Oberle said.

How is global warming affecting the Himalayan rivers? 

Many devotees from all walks of life in India have a lifelong goal of trekking to Gaumukh, where the Ganges River rises from a Himalayan glacier. But, the ice cap at the end of the laborious voyage is melting quickly, predicting a drier future for a nation of 1.4 billion people facing existential threats from climate change.

India is anticipated to be the country most badly impacted, with the number of people worldwide facing water scarcity rising from 933 million (9.3 percent of the total urban population) in 2016 to 1.7-2.4 billion (9.3 percent to nearly half of the total urban population) in 2050, as per the ‘United Nations World Water Development Report 2023: partnerships and cooperation for water’ published by UNESCO. 

On 29th March, the report of the parliamentary standing committee was presented at the Lok Sabha, explaining the issue of the continuous melting and retreating of Himalayan glaciers and the estimated volume loss of glaciers between the years, stating that the Geological Survey of India has conducted studies on their melting by an audit of mass balance studies on nine glaciers and also carried out tracking the recession or advancement of 76 glaciers.

According to the report, “the majority of Himalayan glaciers are reported melting/retreating at variable rates in different places.”

The department stated that melting glaciers as a result of climate change will not only have a negative impact on the flow of the Himalayan river system, but will also cause disasters such as Glacier Lake Outburst Flood (GLOF), glacier avalanche, landslip, and so on.

What factors affect the Himalayan rivers?

There are ten significant river systems in the Himalayas-Hindu Kush region, also known as the Third Pole, due to the volume of water it stores as ice. The tributaries of these river basins provide more than half of India’s water supply. Three million springs, which supply water to 64% of the irrigated land in the Indian Himalayan Region (IHR), are located beyond the main rivers. While the larger rivers provide a means of subsistence for more than 500 million people in the Indo-Gangetic plains, these springs are the lifeblood of mountain villages covering 50 million people across 12 Himalayan states. But they are under a lot of pressure.

1. The climate crisis comes first. According to the World Meteorological Organization, the Himalayan region has experienced a decadal temperature rise that is 0.4°C greater than the global average. The Intergovernmental Panel on Climate Change’s Fifth Assessment Report contained dire predictions: Himalayan glaciers would retreat by 45% by 2100 if surface temperatures increased by 1.8°C. IHR is likely to experience significant effects even if the Paris Agreement’s objectives are achieved.
2. Second, less water flow. Alarming rates of glacier retreat have been observed in the Himalayas. NASA pictures from 2001 revealed that Gangotri had contracted by 850 meters since 1975. Later, an ISRO survey of 2,190 Himalayan glaciers revealed that 75% of them were retreating quickly, on average by 3.75 km every 15 years. About half of the springs in IHR were reportedly drying up, according to NITI Aayog. After a 150-year period, 83% of the springs in Almora had dried up. Even in Sikkim, hardly half of the springs were still producing water.
3. Next is pollution. Our big rivers are commonly regarded as drains. More than six billion liters of sewage are discharged into the Ganga daily, yet only a quarter of that volume can be treated. Delhi is only 2% of the Yamuna’s total length, but it absorbs 70% of the river’s pollutants. The fact that water pollution is harming the upper levels of the Himalayan rivers is less widely understood. According to a 2016 study, rivers in Uttarakhand that provide half of the state’s water are classified as having water quality unfit for human consumption.
4. Finally, development and destruction. Both direct and indirect effects result from the building of big dams, canal diversions, and hydropower projects. Even run-of-the-river projects that obstruct river flow lower downstream farm productivity by increasing siltation and hydropower project efficiency over time. The surface water flow decreases when hydropower projects divert waterways into subterranean tunnels, such as for the tributaries of the Indus, Alaknanda, or Mandakini. Water infiltration into the ground decreases as a consequence. Therefore, neither non-glacial rivers nor mountain streams receive recharging even when erratic rains are present.

References:

1. https://www.thehindu.com/sci-tech/energy-and-environment/major-himalayan-rivers-like-indus-ganges-and-brahmaputra-will-see-their-flows-reduced-as-glaciers-recede-un-chief/article66651551.ece/amp/
2. https://unesdoc.unesco.org/ark:/48223/pf0000383551
3. https://www.unep.org/events/conference/un-climate-change-conference-unfccc-cop-27
4. https://www.thehindu.com/sci-tech/energy-and-environment/a-third-of-world-heritage-glaciers-under-threat-warns-unesco-study/article66095939.ece
5. https://www.unesco.org/reports/wwdr/2023/en
6. https://www.unep.org/events/conference/un-climate-change-conference-unfccc-cop-27
7. https://public.wmo.int/en
8. https://www.nwda.gov.in/upload/uploadfiles/files/Save%20the.pdf
9. https://link.springer.com/article/10.1007/s12403-015-0178-2
10. Image source: https://www.thehindu.com/sci-tech/energy-and-environment/watch-what-is-happening-to-the-worlds-glaciers/article66123420.ece