Hindu Kush Himalaya Snow Update

General Studies Paper-1

Context: The International Centre for Integrated Mountain Development (ICIMOD) has released the snow update Hindu Kush Himalaya between 2003 to 2024.

Snow Persistence

• Snow persistence is the fraction of time snow is on the ground. When this snow melts, it provides water to people and ecosystems.
• In the river basins of the Hindu Kush Himalaya (HKH), snowmelt is the biggest source of water in the streams.
• Overall, it contributes 23% of the runoff to the region’s 12 major river basins every year.

Hindu Kush Himalaya

• The HKH mountains extend around 3,500 km over eight countries — Afghanistan, Bangladesh, Bhutan, China, India, Nepal, Myanmar, and Pakistan.
  • These mountains are also called the “water towers of Asia” because they are the origins of 10 crucial river systems on the continent — Amu Darya, Indus, Ganga, Brahmaputra, Irrawaddy, Salween, Mekong, Yangtse, Yellow river, and Tarim.
  • These river basins provide water to almost one-fourth of the world’s population and are a significant freshwater source for 240 million people in the HKH region.

Status of Snow Persistence

• Ganga River Basin: The Ganga river basin noted its lowest snow persistence in 22 years, 17% below the long-term historical average (also known as ‘normal’).
• Brahmaputra Basin: Snow persistence in the Brahmaputra basin was 14.6% below normal in 2024.
• In the Indus river basin, snow persistence fell 23.3% below normal this year although this was offset by excesses in parts of the lower altitudes.
• Outside India, the basin of the Amu Darya river — which flows through Central Asia — recorded its lowest snow persistence in 2024: 28.2% below normal.
  • The Helmand river, an important source of drinking water for Iran and Afghanistan, was almost 32% below normal in 2024.
  • Persistence in the part where the Mekong river originates in the Himalaya was only slightly below normal this time. (This river’s delta is Vietnam’s “rice bowl”.)
• The persistence of snow in China’s Yellow River basin exceeded the normal value by 20.2% in 2024.
  • In the Yellow river basin, 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.

Reasons for the Lower Persistence

• The primary reason for the lower persistence in 2024 was weak western disturbances.
• Western disturbances are low-pressure systems that originate over the Mediterranean Sea, the Caspian, and the Black Seas and bring rain and snow to the HKH region in winter.
• The region where these storms originate experienced persistently high sea-surface temperatures.
• This disruption weakened and delayed the arrival of the western disturbance, resulting in reduced winter precipitation and snowfall in the HKH region.
• Due to changing climate and global warming, this pattern is becoming increasingly unstable.

Way Ahead

• In the long term reforestation with native tree species can help the ground retain more snow.
• Better weather forecasting and early warning systems can also help local communities prepare for impending water stress.
• Improving water infrastructure and developing policies for protecting areas receiving snowfall are important for long-term change.
• Communities’ involvement in local, national level decision-making and promoting regional cooperation are vital for comprehensive solutions for the sustainability of snow.