TAG: GS 3: ECOLOGY AND ENVIRONMENT
THE CONTEXT: The 2024 Hindu Kush Himalayas (HKH) snow update by the International Centre for Integrated Mountain Development (ICIMOD) provides a comprehensive analysis of snow persistence in the HKH region.
EXPLANATION:
- The report reveals alarming trends in snow cover, which have significant implications for water resources in this crucial area, often referred to as the “water towers of Asia.”
Snow Persistence in the Hindu Kush Himalayas
- Snow persistence is the fraction of time snow remains on the ground.
- This parameter is crucial as snowmelt significantly contributes to water availability in the HKH region.
- It supports the flow of streams and rivers, essential for both ecosystems and human populations.
- Snowmelt accounts for approximately 23% of the annual runoff in the HKH region’s 12 major river basins.
- These mountains stretch over 3,500 km and are vital sources of freshwater for about 240 million people in the HKH region, as well as nearly a quarter of the global population through their river systems.
Key Findings of the 2024 Report
- General Trends:
- The report analyzes data from 2003 to 2024, identifying significant fluctuations in snow persistence between November and April each year.
- The most concerning finding is the significant drop in snow persistence across several major river basins in 2024.
- Specific River Basins:
- Ganga River Basin: In 2024, the Ganga river basin experienced its lowest snow persistence in 22 years, 17% below the long-term historical average.
- Brahmaputra River Basin: Snow persistence in the Brahmaputra basin was 14.6% below normal in 2024.
- Indus River Basin: The Indus basin saw a 23.3% decrease in snow persistence in 2024, though some lower altitudes experienced an offset.
Global and Regional Implications
- Amu Darya and Helmand Rivers: Outside India, the Amu Darya basin recorded a 28.2% drop below normal, and the Helmand river basin saw a nearly 32% decrease, setting new records.
- Mekong River: Slightly below normal snow persistence was observed in the Mekong river’s origin area, impacting the broader region known as Vietnam’s “rice bowl.”
Global and Regional Implications
Higher snow persistence
- The persistence of snow in China’s Yellow River basin exceeded the normal value by 20.2% in 2024.
- The Yellow river basin is an area where the East Asian winter monsoon brings cold, dry air from Siberia and Mongolia.
- When this cold air mass interacts with moist air from other regions, particularly the Pacific Ocean, it can result in snowfall over the higher altitudes of the upper Yellow River basin.
- When the cold air from the east Asian winter monsoon systems interacts with moist air masses from the Pacific Ocean, it can result in snowfall at higher elevations in the eastern Himalaya.
Causes of Declining Snow Persistence
- Weak Western Disturbances:
- The primary reason for reduced snow persistence in 2024 was identified as weak western disturbances.
- These are low-pressure systems originating over the Mediterranean, Caspian, and Black Seas, which bring precipitation to the HKH region during winter.
- Impact of Global Warming:
- Changing climate and global warming contribute to the instability of these weather patterns.
- Higher sea-surface temperatures in regions where these disturbances originate have weakened and delayed their arrival, resulting in reduced snowfall.
- Influence of La Niña and El Niño
- The recurring La Niña–El Niño conditions, influenced by global warming, exacerbate the instability of weather patterns, impacting snow accumulation and persistence.
Consequences for Water Resources
- Ganga Basin: Snowmelt contributes 10.3% of the water in the Ganga basin, highlighting the critical role of snow persistence.
- Brahmaputra and Indus Basins: Snowmelt accounts for 13.2% and approximately 40% of the water in the Brahmaputra and Indus basins, respectively. Lower snow persistence threatens water availability, particularly if there is less early-season rainfall.
- Water Supply Risks: The decline in snow persistence endangers the water supply for millions of people, exacerbating the challenges posed by climate change in one of the world’s most populated regions.
Strategies for Mitigation and Adaptation
- Reforestation: Planting native tree species can help retain more snow on the ground.
- Improved Infrastructure: Developing better water infrastructure and policies to protect snowfall areas is crucial for long-term sustainability.
- Weather Forecasting: Enhancing weather forecasting and early warning systems can help communities prepare for water stress.
- Community Involvement: Engaging local communities in decision-making processes at national and regional levels is vital for comprehensive solutions.
- Reducing Emissions: Mitigating global warming by reducing emissions is critical. This involves building political will among governments and business leaders to reduce fossil fuel consumption, particularly in G-20 countries, which are responsible for 81% of global emissions.
