Climate Change Impact on Gangotri Glacier System
Recent studies reveal climate change effects on the Gangotri Glacier System (GGS), important Himalayan glacier feeding the Ganga river. Data from 1980 to 2020 show reduced snowmelt due to rising temperatures and changing precipitation patterns. This has altered the glacier’s hydrology, with implications for water availability, agriculture, and hydropower in northern India.
Gangotri Glacier System
- The GGS is one of the largest glaciers in the central Himalayas.
- It supplies the Ganga river, supporting millions downstream.
- The glacier’s flow comprises snowmelt, glacier melt, rainfall-runoff, and base flow. Snowmelt dominates, historically contributing about 64% of annual flow.
Changes in Hydrological Composition
- Over four decades, snowmelt’s share declined from 73% (1980-90) to 63% (2010-20).
- Glacier melt contributes 21%, rainfall-runoff 11%, and base flow 4%.
- A notable rise in snowmelt proportion occurred during 2010-20 due to colder winters and increased winter precipitation, temporarily boosting snow accumulation.
Temperature Rise and Its Effects
Mean temperatures in the GGS region increased by 0.5°C between 2001-2020 compared to 1980-2000. This warming causes earlier summer melting and shifts peak river discharge from August to July. Such shifts affect water availability for irrigation, hydropower, and local communities.
Declining Snow Cover
Snow cover area is decreasing due to warming, reducing snowmelt volume. Glacier thickness is shrinking at an average rate of 46 cm per year. The glacier snout is steadily receding, indicating long-term ice loss. Rainfall-runoff and base flow have increased, compensating partially for reduced snowmelt.
Implications for Water Security
Changes in flow timing and volume threaten water security in the Ganga basin. Earlier peak discharge may cause water shortages in late summer. Reduced snow accumulation impacts dry season flows. These shifts pose challenges for hydropower generation and agriculture dependent on glacier-fed rivers.
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