Glaciers and food nexus: glaciers’ contributions to food security in mountain and lowland areas.

 

Mountains and glaciers are crucial for food security. Water originating from these high-altitude regions irrigates lowland farms and sustains the livelihoods of mountain communities. Sustainable agricultural practices and agrifood systems offer key solutions to food security and the climate crisis and are critical in Preserving glaciers (FAO, 2025c). Agroforestry, agroecology, terrace farming, sustainable soil management and watershed management are some examples of agricultural practices which protect mountain ecosystems (FAO, 2024).

 Glacial melt is an important seasonal source of water for irrigated agriculture in mountains, particularly in the dry season. There is evidence that a reduction in streamflow due to glacier melt or reduced snow cover has led to reduced water availability for the irrigation of crops, leading to a decline in agricultural yields in several mountain localities (Hock et al., 2019). These include the Peruvian Andes, which have experienced reduced seasonal runoff due to glacier retreat that negatively affects crops (Bury et al., 2011), along with the high mountains of Asia (Rasul and Molden, 2019). For example, the Karakoram in Pakistan has experienced reduced seasonal water availability for irrigated crops due to glacial retreat and reduced snow cover (Nüsser and Schmidt, 2017). Conversely, in the Southern Andes, increased streamflow in the Elqui River in Chile, due to glacier retreat or changing snow cover, has led to increased water availability for irrigation and increased agricultural yields (Young et al., 2010). 

Reductions in snow cover can also affect agriculture through direct impacts on soil moisture. Rural communities depend on adequate levels of soil moisture at planting time, Reduced soil moisture has been reported in Nepal, where less snow cover has led to the drying of soils and lower yields of potatoes and fodder (Smadja et al., 2015; Hock et al., 2019).

 Pastoralism is an important livelihood strategy in many mountain regions. Changes in snow and glaciers are adversely affecting herders at their summer residences and winter camps, for example in the Himalaya (Namgay et al., 2014) and Scandinavian mountain regions (Mallory and Boyce, 2018). Increased glacier meltwater has caused lakes on the Tibetan Plateau to increase in size, covering pasture areas and leading pastoralists to alter their patterns of seasonal movement (Nyima and Hopping, 2019). However, rising temperatures, with associated effects on snow cover, also have some positive impacts. Seasonal migration now starts earlier in Northern Pakistan and residence in summer pastures lasts longer (Joshi et al., 2013; Hock et al., 2019). 

Globally, water from mountains makes a significant contribution to supplying irrigation in lowlands downstream. The contribution of mountain water to irrigation, however, varies according to different river basins and regions. Glacier and snowmelt contributions are particularly important in river basins where other blue water resources, such as lakes, rivers or groundwater, are scarce. (Viviroli et al., 2020). Glacial meltwater provides an important source of water in the dry season for summer irrigation in downstream lowlands. It can reduce the variability of river runoff from year to year, in some cases at distances of hundreds of kilometres (Hock et al., 2019). 

Lowland agricultural areas that receive irrigation water from rivers fed by glacier melt and snowmelt are projected to face negative impacts in some regions, due to reduced melt and runoff as glacial mass and snow cover decline over time (Hock et al., 2019; Viviroli et al., 2020). Changes in the onset of spring melt and peak snowmelt are predicted to alter the timing of irrigation water delivery downstream in the Hindu Kush Himalaya region and Central Asia (Hock et al., 2019). Some areas of the Indus basin depend on glacier and cryosphere melt to supply lowland irrigation in the dry season (Biemans et al., 2019)

Changes in water quality related to glacier and cryosphere melt have the potential to negatively impact agriculture in some mountain localities, where cryosphere melt makes a significant volumetric contribution to streamflow. This includes increased river sedimentation, leading to clogging of small-scale mountain irrigation systems and reducing efficiency; increased heavy metal concentration, leading to soil contamination and loss of productivity, with the potential for crop uptake and associated human health risks; and changes in nutrient concentration within mountain waters and downstream, impacting water chemistry, with implications for soil fertility and crop growth (Hock et al., 2019).