Declining Snow Persistence in the Hindu Kush Himalaya

GS3 – Environment

Context:

A recent report by ICIMOD highlights that the Hindu Kush Himalaya (HKH) region has witnessed a third consecutive year of below-average snow persistence, with 2024-25 marking historic lows, posing serious threats to water security across Asia.

Understanding Snow Persistence:

• Snow persistence measures the proportion of time snow covers the ground during the snow season (November to March).
• Melting snow accounts for approximately 23% of the yearly runoff across 12 major river basins in the HKH, supporting billions living downstream.

The Hindu Kush Himalaya:

• Stretching over 3,500 km, the HKH spans eight countries: Afghanistan, Bangladesh, Bhutan, China, India, Nepal, Myanmar, and Pakistan.
• Known as the “water towers of Asia,” these mountains are the sources of ten vital river systems, including the Amu Darya, Indus, Ganga, Brahmaputra, Irrawaddy, Salween, Mekong, Yangtze, Yellow, and Tarim rivers.
• The river systems originating here provide freshwater to nearly a quarter of the global population and are crucial for the livelihoods of communities within the HKH.

Concerning Trends in Snow Persistence:

• Record Low: Snow persistence during the 2024-25 winter season fell to 23.6%, the lowest in two decades.
• Repeated Shortfalls: Four out of five winters between 2020 and 2025 recorded lower-than-normal snow cover.
• Worst-Affected Basins:
  • Ganga Basin: 24.1% below normal
  • Indus Basin: 24.5% below normal
  • Mekong Basin: 51.9% below normal
  • Salween Basin: 48.3% below normal
  • Tibetan Plateau: 29.1% below normal
• Impact: Over 2 billion people, dependent on these rivers for drinking water, agriculture, and energy, face increasing water stress.

Drivers of Declining Snow Persistence:

• Climate Change: Regional temperatures in the Himalayas have been rising faster than the global average for more than four decades.
• Land Use Changes: Urbanisation and alterations in land systems are exacerbating warming trends.
• Weaker Western Disturbances: A decline in extra-tropical storm activity has disrupted the region’s winter snowfall patterns.
• Reduced Runoff: A thinner snowpack leads to diminished river flows during early summer.

About ICIMOD (International Centre for Integrated Mountain Development):

• Established in 1983, ICIMOD is an intergovernmental organisation based in Kathmandu.
• It works with the eight HKH countries, focusing on scientific research, field-based solutions, and policy support for mountain development and climate adaptation.