Himalayan glaciers are more than water towers
ESA
Every summer, rivers flowing down from the Himalayas irrigate farms, generate electricity and provide drinking water to millions of people. Far upstream, these rivers begin in a landscape of ice, rock and snow that is often described as the “water towers of Asia”.
But Himalayan glaciers do more than store and release water. In the Indian Himalayan Region (IHR), they are part of ecosystems that regulate climate, support biodiversity, influence agriculture, buffer disasters, contribute to tourism and shape the cultural identity of mountain communities.
Yet the way glaciers are discussed and assessed often focuses on their retreat, glacial lake outburst floods (GLOFs) and their implications for water security. The wider range of benefits they provide receives less attention in economic planning and public policy. This can leave important ecological services outside conventional measures of value.
A recent landmark review, Mapping the Ecological Worth of Glaciers of the Indian Himalayan Region, published in Ecological Indicators by A.R. Arya and Harini Santhanam, examines this wider role. The authors reviewed 122 scientific studies published over the past two decades and argue for greater recognition of glaciers as providers of multiple ecosystem services.
The review also identifies gaps in existing research and suggests ways of bringing ecosystem services into climate adaptation and natural resource governance. As climate change accelerates glacier retreat, understanding these multiple roles becomes increasingly important.
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Freshwater security in the Indus, Ganga and Brahmaputra river basins is central to discussions about Himalayan glaciers. However, viewing glaciers only as reservoirs of water leaves out many of their other functions. Using the Common International Classification of Ecosystem Services framework, the review identifies 21 ecosystem services provided by western Himalayan glaciers across four categories.
Provisioning services include drinking water, irrigation and hydropower. Glaciers also provide regulating services by moderating regional climate, reducing flood risks, maintaining water quality and contributing to groundwater recharge.
Their role extends further. Supporting services include biodiversity and nutrient cycling, while cultural services are linked to tourism, local livelihoods and spiritual heritage. These services are interconnected. Water regulation affects agriculture and local livelihoods, while healthy ecosystems support tourism and contribute to climate resilience. Looking at each service separately can therefore obscure the wider consequences of glacier loss for downstream ecosystems and communities.
The review finds that scientific understanding of Himalayan glacier ecosystem services remains incomplete. Research on glacier retreat and hydrology has grown rapidly since 2015, but studies assessing ecosystem services have not kept pace. Of the studies reviewed, 82% identify ecosystem services, 10% quantify them and only 8% attempt to assign them an economic value. This creates a challenge for policy. Services that can be measured financially are easier to incorporate into conventional economic planning, while ecological benefits that are harder to quantify can remain outside such assessments.
The review also identifies thematic, geographical and methodological gaps. Research has focused largely on provisioning services that are relatively easy to measure, while regulating, supporting and cultural services receive less attention. Studies are also concentrated at lower elevations, between 500 and 2,500 metres, with less research in areas above 4,000 metres where important ecological processes originate. Much of the research relies on perception surveys rather than field measurements or hydrological modelling.
Glacier mass balance is another important gap. It directly influences water availability and ecosystem functioning. The authors therefore call for approaches that bring together hydrological modelling, ecological monitoring, economic valuation and social dimensions. Understanding these gaps matters because glacier retreat affects not just the quantity of water available but also when that water reaches downstream areas and the risks associated with changing ice and water systems.
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As glaciers retreat, the effects extend beyond the loss of ice itself. Accelerated melting can increase hazards such as GLOFs, landslides and rock ice avalanches, while also changing the timing of river flows. In the short term, faster melting can increase river discharge. But as glacier mass is lost, dry season flows can eventually decline. This creates uncertainty for agriculture, hydropower generation and urban water infrastructure designed around historical climate conditions.
The implications extend across South Asia. More than 268 million people in the Indus Basin, along with millions of people dependent on the Ganga and Brahmaputra rivers, face risks associated with both excessive meltwater flooding and shortages during lean seasons. Local factors can add to these pressures. Black carbon from fossil fuels, forest fires and biomass burning darkens snow and ice, reducing their reflectivity and accelerating melting. The review notes that reducing local black carbon emissions through air quality management and clean energy transitions can provide direct benefits.
The authors also point to the role of nature-based climate solutions in the western Himalayas. Watershed restoration, afforestation and wetland management can help stabilise slopes, prevent erosion and regulate sediment transport in glacier fed catchments. This shifts the focus from individual glaciers to the wider mountain landscape in which they function.
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Recognising these services also raises a question about how they should be valued. Water supplied for drinking, irrigation and hydropower generates visible economic returns. Other services, including flood regulation, sediment transport, biodiversity and cultural values, are less commonly included in conventional accounting.
The review therefore calls for a comprehensive ecosystem accounting framework to complement traditional Environmental Impact Assessments (EIAs). Infrastructure projects, it suggests, need to consider cumulative impacts on flood regulation, sediment transport and future water security rather than examining developments separately.
Economic and technical tools can support this approach. Willingness to pay assessments, including tourist contributions in Ladakh, could provide mechanisms for funding watershed restoration and local monitoring. At the same time, satellite remote sensing and hydrological modelling can be combined with socioeconomic data to improve understanding of glacier ecosystems and bring their value into development planning.
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The review ultimately points towards a systems approach. Policy frameworks need to consider entire river basins, glacier mass balance and connections between ecosystems rather than treating glaciers as isolated bodies of ice. Communities living with and depending on these ecosystems also have a role. The review identifies participatory monitoring, watershed restoration and payment for ecosystem services as possible ways of involving local communities in conservation and management.
Monitoring glacier retreat remains important, but the review argues that it cannot be the only measure of glacier health or value. Long-term glacier modelling, mass balance tracking and ecological valuation need attention alongside physical infrastructure such as roads, dams and tourism developments.
Himalayan glaciers connect mountain ecosystems with the farms, settlements and economies downstream. Their contribution is therefore not limited to the water they release. Recognising the range of services they provide can help bring ecological functions, economic value and community dependence into the same conversation. For India, the challenge is to ensure that decisions about development and climate resilience account for this wider role before these services are permanently lost.