Context: Study on the impact of global warming and climate change on the snowpack’s and glaciers of the Himalayan region and the rivers that they feed.
Methodology of the study

• The study involved analyzing the impact of different components – rainfall-runoff, snow-melt and glacier-melt on Himalayan Rivers.
• The team studied five basins in the central Himalaya – Sutlej, Thulo Bheri, Kali Gandaki, Dudh Kosi and Arun.
• The team developed a new glacier melt model and integrated it to the currently used land surface model to make the integrated model more accurate.
• The currently used land surface model does not take into account glacier melt and thus could lead to serious errors in the study of north-Indian rivers.

Important observations

• The study notes that if drier and warmer scenarios continue in the near future (2031–2050), the catchment areas are more likely to face a water stress.
• Snow will melt easily in a warming climate and should contribute to water flow in the region. However, the reduced snowfall will in turn reduce the amount of snow-melt.
• Though glacier melt will increase initially, they will shrink in size quickly and the amount of glacier melt will also decline in the latter end of the century.
• The study also notes that if there is increased rainfall, this could lead to a water surplus situation in the region.

Concerns

• The glaciers of the Himalayas are important sources of water for about a billion people who live in the basins of the Indus, Ganges and Brahmaputra rivers. 
• This along with changing patterns of precipitation systems — Indian Summer Monsoon and Western Disturbances — could adversely impact water security of the region. Water insecurity poses a grave threat to the habitants of this region.
• The global warming would also affect the Himalayan hydrology. India, Nepal, Pakistan and China hugely depend on these Himalayan Rivers for their energy production.
• Human activities profoundly affect the earth’s climate and mountains are a sensitive indicator of that effect. The mountain ecosystem is easily disrupted by variations in climate owing to their altitude, slope and orientation to the sun.
• Several scientists believe that the change occurring in the mountain ecosystems may provide an early glimpse of what could come to pass in a lowland environment. 
• As the earth heats up, mountains glaciers melt at unprecedented rates, while rare plants and animals struggle to survive over ever diminishing areas. As a result, people living in the mountains face a great deal of hardship.

Melting Glacier

• Melting of Himalayan glaciers has doubled since the start of the 21st century due to rising temperature, losing over vertical foot-and-half or ice each year and potentially threatening water supply for hundreds of millions of people in counties, including India.
• An analysis spanning 40 years of satellite observations across India, China, Nepal, and Bhutan indicated that climate change is eating the Himalayan glaciers, according to a study published in 2019. 
• According to experts, reduced snowfall this winter in Uttarakhand may have played a major part in the glacier bursts. Uttarakhand is a wake-up call, not just for the rulers and people in the state, but also the planners and decision-makers all over the country.
• The potential of cumulative effect of multiple such projects has turned out to be more environmentally damaging than sustainable, given the current policy of the state government of pursuing hydro-power projects indiscriminately.
• Changes in the volume of mountain glaciers and in their seasonal melting patterns have a great impact on water resources in many parts of the world. Changes in water availability due to glacier melting because of evident change in climate are taking place at a time when pressure on water resources for irrigation and food production, industrialisation and urbanisation is increasing.
• The entire State of Uttarakhand is categorised as falling in Zone IV and V of the earthquake risk map of India. Previously, the region has witnessed devastating earthquakes and in the recent past earthquakes in Chamoli and flood in Kedarnath has been witnessed.

Road Ahead

• Despite the threat of such calamity and knowing that mountains provide large amounts of water run-off for run-of-river projects from melting snow and glacier ice, glacier lakes can pose a significant hazard and bursting of glacial lakes can cause flash floods with catastrophic consequences, the large hydropower projects are in vogue in the state. Sustainable water-management practices and better governance structures are required.