Glacier melt due to climate change could alter downstream water quality

New research shows glaciers are also active chemical systems and climate warming may be altering not just how much water they release, but also its quality, says a Mongabay-India (MI) report. Citing a new study on the Rulung Glacier in India’s Ladakh region, the report say that researchers found that rising temperatures and faster glacier melt are intensifying interactions between meltwater and the rocks beneath the ice, altering the chemistry of water flowing into the Indus river basin. Researchers say these changes could affect river ecosystems, agriculture, and drinking water supplies downstream.

The study, published in Physics and Chemistry of the Earth journal, examined meltwater from Rulung Glacier at four sites during the ablation period (annual melt season) in 2023 and 2024. The researchers used a combination of field sampling, hydrochemical analysis, and statistical interpretation techniques to understand how glacier meltwater chemistry changed within a year. Due to their isolation, glacier-fed lakes are well-known for the untainted and pure water they hold.

The study also found that rising temperatures and faster glacier melt are intensifying chemical weathering and altering meltwater chemistry in the Ladakh region. prolonged warming and increasing glacier retreat may increase the exposure of fresh rock surfaces, enhance oxidation reactions, and potentially increase the amount of trace metal into downstream river systems. Researchers add that for agriculture, glacier-fed rivers are a lifeline across the Indus basin. Moderate mineral inputs can benefit soils by supplying nutrients such as calcium and magnesium, shares Lone. However, excessive dissolved salts or trace elements over long periods may gradually reduce soil quality, affect crop productivity, and contribute to salinisation in already water-stressed regions.

The study explains that glacial lakes are bodies of water that are located in, out of, beneath, besides or in front of glaciers and are formed through the processes of glaciers, such as retreating or melting. In the semi-arid industrial and agricultural areas of the Himalayan region downstream, the snow and melting glaciers provide substantial amounts of freshwater. The seasonal melting of snow and glaciers regulates water flow, ensuring sustained agricultural productivity, drinking water supply, and hydropower generation downstream. However, the growing impacts of climate change are altering the Himalayan cryosphere, posing serious risks to water security, biodiversity, and regional socio-economic stability. Protecting this critical mountain system is therefore essential for the environmental and human well-being of a significant portion of the world population. The main supply of freshwater for those downstream is the meltwater flow from glaciers. The growing need for freshwater in downstream sectors makes hydrochemical research of glacier meltwater important.

Quoting another article published in the International Journal of Water Resources Development (IJWRD), the MI report points out that the Hindu Kush Himalayas (HKH) are called the water towers of Asia. The IJWRD article highlights that the HKH region is the source of 10 major rivers and have the largest snow and ice deposits outside the two poles. According to the article, water emanating from these rivers provides food, energy and ecosystem services to up to 1.3 billion people. Climate change and socio-economic and demographic changes have put unprecedented pressure on these water resources, leading to uncertain supplies, increased demands and higher risks of extreme events like floods and droughts.

The HKH region is the source of 10 major rivers: the Indus, Ganges, Brahmaputra, Irrawaddy, Salween, Mekong, Yangtze, Yellow, Amu Darya and Tarim. These rivers directly serve 210 million people who live in the HKH region and serve 1.3 billion people who live downstream of these river basins. The region has the highest concentration of snow and glaciers outside the two poles and is often referred to as the Third Pole. All 10 main rivers of the HKH are snow and glacier fed and hence perennial. They serve some of the most highly populated regions of the world with water for food, energy and domestic uses; they have nurtured great civilizations and sustained important ecosystems. Yet, these water systems are at a crossroads due to climate, socio-economic and demographic changes. This is exemplified by increasing water demand and further exacerbated by uncertainties about future availability and increase in incidence of extreme events like floods and droughts.