The massive and deadly floods on the Nepal-Tibet border are a stark reminder of why the world needs to constantly update its understanding of the fragile ecosystem in the Himalayas.

These towering mountains contain nearly 90,000 glaciers, which sustain ten major river systems. Countries nearby, including India, Pakistan, China, Afghanistan, Nepal and Bhutan, are reliant on water resources that cross borders here. As major river-based hydro economies, their agricultural production, energy security and wider economic stability depend on the availability and the timing of river flows.

Changes in snowmelt, glacier retreat and water availability can cause untold hardship for millions of people relying on it. It can also create incredible danger as seen in August 2026, when a flash flood caused by a collapsed glacier washed away villages, bridges and roads on both sides of the Tibet-Nepal border, killing more than 1,000 people.

Understanding and measuring winter snowfall in these regions is exceptionally important. It is the main source of freshwater when it is released by snow melting during the region’s warm and early-summer crop growing seasons, when local communities need it most.

---

Read more: Nepal-Tibet disaster linked to climate change – a glaciologist explains

---

Understanding future Himalayan hazards

No one knows precisely how much water the mountains currently provide, and how this will change. This knowledge gap also hinders our understanding of the occurrence of geo-hazards including avalanches triggered by extreme snowfall events and flooding caused by the rapid melting of snow.

The recent Nepal disaster could be related to a spell of unusually warm weather. This may have weakened the snowpack creating a rapid melt. I work with a team of glaciologists at the British Antarctic Survey, whose team had sensors six miles (10km) away from the site. Results suggest that enhanced melting could have introduced water into the crevasses weakening the ice-rock connections.

Studies project that roughly half of the glacier ice in the Himalayas (equivalent to about two billion Olympic swimming pools) could melt by the end of this century – enough to raise sea levels by over a centimetre but there is still considerable uncertainty in these projections.

This is because we do not have enough measurements of snowfall and ice across large areas in this challenging terrain. As a result, scientists often have to extrapolate from relatively small numbers of observations to enormous and highly varied terrain.

Computer-based tools (known as models) that combine available observations with information about land and the atmosphere have proved to be indispensable and often come to rescue when gap-filling is necessary. But models are only as good as the observations used to constrain them.

New scientific approaches are beginning to offer solutions, but they are rather sparse and insufficient on their own beyond the region where they have been tested.

For example, my recent study with colleagues found a new way to accurately measure mountain snowfall reducing measurement errors dramatically – measuring snow has been a long-standing problem because of which mountain water resources have been hugely underestimated over the years.

Another regional study recently reported a measure of the water stored in some of the key Nepalese glaciers using an airborne method that involves taking an aerial survey of the region using instruments mounted on a helicopter. Scientists are also using a technique known as radar interferometry, which uses a combination of radio waves to detect very fast-moving mountain slopes that risk collapsing.

A combination of one or more such techniques could be used to predict where snowfall is concentrated, how much water it is likely to contribute to the region and also identify areas at risk. New information could be used to cast early warning preparedness strategies feeding into a forewarning system for timely evacuation of the region’s most vulnerable.

What happens next?

Scientific innovation alone will not be enough. There is an urgent need for proven ideas to be commercially adapted and systematically deployed across critical zones. The numbers and the imminent dangers involved can now no longer be left to discussions in research papers and conferences, they must be made public on the equivalent of a war footing.

An evacuation success story from the Swiss village of Blatten in 2025 shows what this can achieve. Hundreds of people were moved out before a huge section of the glacier broke off. The authorities had already identified areas at risk and publicly shared hazard maps. Continuous monitoring of the landscape, precipitation and ground movement fed into an early warning system.

But success stories from the west cannot simply be transplanted wholesale into the Himalayan context because of the region’s inhospitable elevation, harsh weather and limited infrastructure. An approach that factors in indigenous and traditional knowledge should be part of plans and policies.

What is also needed in the Himalayas is a far more highly coordinated monitoring network that brings together everyone who depends on and manages mountain water. This would include potential state and non-state organisations, researchers, local authorities and mountain communities. Communities should be central to this effort. Local people can help install and maintain monitoring equipment, collect observations and contribute knowledge of their own environment.

Examples of existing successes from the region include the use of community-managed reservoirs to artificially store meltwater, the construction of ice stupas (an artificial glacier) and glacier grafting techniques to grow new, water-producing glaciers designed to gradually release water during the growing season. The community-based flood warning system in parts of Nepal’s Koshi basin is a success story but is limited in its approach to provide alerts during a cascading disaster, such as the one we witnessed recently.

These results should help policymakers and scientists understand how communities dependent on mountain ecosystems are responding to change – and what support they need to adapt to reduce their vulnerability to future hydro-climatic shocks, such as droughts and floods.

Regardless of the current changes in Himalayan snowfall and glacier melt, local people need to play a vital role in helping measure what is happening in the climate system. And that, as well as countries working more closely together, should help with the future planning that is desperately needed.

Siddharth Gumber receives funding from the National Environmental Research Council (NERC), The TEAMx-FLOW project (NE/Z50399X/1).

Mountain snow and meltwater from glaciers in the Himalayas determine how much water is available for drinking, farming and hydropower for millions of people in India, Pakistan, Nepal, China and Afghanistan.

This is especially important during the spring and early summer crop-growing season when meltwater helps sustain the flow of rivers and provides the region with a vital buffer against the worst impacts of a dry season or drought. Because many of these rivers cross national borders, changes in water supply can also heighten regional tensions when resources are scarce.

Meltwater from snow is one of the pillars of survival – but it’s proved difficult in the past to get accurate measurements across this challenging terrain.

So measuring where and how much snow falls is essential. My team’s new research gives improved estimates of snowfall across the west-central Himalayas. Results show that in just one winter, the previous best available snowfall analyses underestimated total seasonal snowfall by 37% over Lake Hampta area in Himachal Pradesh. By including new snowfall observations, we reduced that error dramatically.

Why snowfall predictions have been wrong

Because most instruments were originally designed to measure rain over very small areas, rather than snowfall spread across large areas, most calculations of snowfall levels have historically been inaccurate. A rain gauge around the size of a dinner plate was used in the past – too small for the purpose and therefore missing large amounts of snow. These small devices were particularly bad at catching snow during strong winds. As a result, mountain water resources are often misunderstood and have been underestimated by 50–100% over the years.

To change this, we developed a new way to measure snowfall using commercially available water-pressure sensors deployed on the lakebeds. The team installed these instruments at three lakes – Ghepan and Hampta in the western Himalayas, and Mugu in Nepal. Unlike conventional instruments, these sense the whole lake surface – an area of thousands to billions of square metres – to measure the timing and intensity of snowfall. These use water pressure in lakes to directly measure the mass (water content) of accumulating snow, providing an accurate and unbiased estimate of snowfall. This is based on Archimedes principle of displacement: as snow accumulates on a frozen lake, it changes the water pressure beneath.

Snowfall from these devices was analysed and used to refine physical processes in a weather model. This is the same model which provides weather predictions over the UK but is customised for mountainous regions. The results show the model can generally reproduce both when the snow falls and how much accumulates, and is particularly good at representing extreme snowfall events. We now have new insights into where and when snow falls across the region at much finer detail than previous estimates, making mountain water resources more predictable. In contrast, a snowfall map based on previous analysis shows a much more uniform distribution and considerably less snowfall.

Planning for water shortages

This information could help regional communities adapt and improve water planning, help manage reservoirs and protect vulnerable infrastructure from snow-related hazards. It could also support engineering interventions such as snow harvesting in areas that receive abundant snowfall, for example, by artificially storing meltwater in community-managed reservoirs and into ice stupas (an artificial glacier) designed to gradually release water during the growing season.

An understanding of when snow falls will be crucial for predicting when it will melt and how much water will flow into rivers and help communities and policymakers better prepare for future water shortages.

The Himalayan ice fields are important because they are the largest permanent ice-cover outside of the polar regions and contain some of the largest reservoirs of freshwater on earth.

With this region starting to see more water shortages it’s time to start reassessing reliance on mountain water supplies. But how much water the mountains provide, and how it will change, remain remarkably uncertain.

Good measurements of snowfall are now more important than ever for predicting the future of water resources, which until now have been lacking. For example, a single long-running active weather station above 4,000 metres has provided one of the few continuous snowfall records across the vast 566,000 square kilometres of Himalayan headwaters that feed the Brahmaputra, Indus and Ganges river basins.

This work is also deeply personal for me. I grew up in a city just 50 kilometres from the outer Himalayas. On family holidays, I was captivated by the thriving beauty of pines and junipers against the backdrop of the Himalayas, while learning that mountains and rivers are more than just landscapes. Those experiences fostered a lasting connection to the region, and I continue to return to the mountains whenever I can.

Water is a precious commodity upon which every society depends, and shortages can cause untold misery.

With better snowfall estimates, we are already beginning to understand how to make the future of the mountain eco-system more predictable, and help people cope.

Siddharth Gumber receives funding from the National Environmental Research Council (NERC), The Big Thaw project (NE/X005267/1).