Low snow levels in the Himalaya are putting lives at risk

Snowfall in the Hindu Kush Karakoram Himalayas (HKKH), straddling South, Central, and East Asia, was extraordinarily low in 2024. Depleting snow cover poses a significant threat to billions of people who rely on snow and glacial meltwater for agriculture, and drinking water.

Known as the Third Pole, the HKKH spans approximately 4.2 million square kilometres across eight countries and serves as the source for Asia's major rivers, including the Indus and the Ganges. These rivers depend heavily on snow and glacial meltwater, making upstream snow and ice reserves crucial for seasonal water availability.

However, rising temperatures and changing precipitation patterns are accelerating snowmelt, reducing seasonal snowpack, and decreasing snow persistence (the fraction of time snow remains on the ground)^1,2. The Ganga River basin recorded its lowest snow persistence at 17% this year, a sharp decline from previous years. In 2018, snow persistence was at 15.2%, while the highest recorded was 25.6% in 2015.

Western Disturbances (extratropical storms from the Mediterranean) significantly impact the regional climate by contributing to winter precipitation in the Himalaya. Weaker Western Disturbances disrupt the timing of seasonal snowfall, leading to delays and shifts in snowfall patterns. This late winter snowfall results in early melt due to increased air temperatures in late winter and early spring, causing lower snow persistence — a trend observed across the Himalaya.

Shepherds in the Himalaya, such as Prem Lal from the Chamba district of Himachal Pradesh, are severely affected by these changes. Prem Lal, who migrates to the Lahaul and Spiti region during summers, says over the past few years, winters have become milder and the snowfall decreased significantly.

He fears that their traditional way of life may no longer be viable. "This change in climate is deeply affecting our way of life. The grazing lands that used to be lush with grass are now dry and barren, and have disrupted the traditional routes, forcing us to move our flocks higher up into the mountains in search of better pastures," says Lal.

The implications of low snow cover and low snow persistence for regional glaciers are profound. Snow covering the glacier surface increases its reflectivity (albedo), bouncing back more solar energy and absorbing less heat, which helps prevent melting. Fresh snow typically reflects over 80% of incoming solar radiation, while bare ice or snow that absorbs impurities such as dust or soot, exhibit much lower albedo values. A thick snow cover also acts as an insulating layer, protecting glacier ice from direct exposure to solar radiation and warmer air temperatures, thereby slowing down ice melt. Reduced snow persistence and early snow melt expose larger areas of dark glacier ice, decreasing overall albedo and accelerating melting.

Snow plays a crucial role in glacier mass balance and growth. Snowfall accumulation compacts under additional layers, transforming into firn — a dense, granular form of snow — and eventually into glacial ice through further compression and recrystallization. Understanding these dynamics is essential for predicting glacier behaviour and managing water resources in regions reliant on glacial meltwater.

Satellite and in-situ observations show a consistent global trend of mountain glacier recession over the past few decades, largely because of anthropogenic factors leading to rising air temperatures, increased precipitation and rain, and heightened snowmelt. River basins such as the Indus and Ganga, heavily dependent on snowmelt and glacier meltwater, face significant threats. Future projections indicate that glacial and snowmelt water will peak by mid-21st century and subsequently decline due to glacial mass loss and reduced snowfall at higher elevations.

There is an urgent need for more scientific and societal information about precipitation in the region. Increased high-altitude meteorological observations and improved regional climate models are essential to understanding and preparing for an uncertain future³.