Water supply from icy mountains will become less reliable

Icy mountains, with their snow, glaciers and permafrost, are important sources of water for downstream communities in many parts of the world. Some scientists refer to these frozen bodies as the ‘water towers of the world,’ since they store water during the cold winter months and release it slowly as meltwater during spring and summer, meeting the needs of people and ecosystems in lower lying areas. 

However, as global warming takes effect, glacial ice and permafrost are receding or disappearing from these mountain regions, necessitating new water management strategies to ensure the continued stable supply of fresh water. Essentially, as ice melts in mountainous regions throughout the world, the glaciers, snow and permafrost no longer act as storage reservoirs, meaning that water supply in these regions will be provided solely by precipitation. Previous research has suggested that, by 2100 up to half of the world’s population could be living with water scarcity. 

A recent study led by researchers from the University of Birmingham suggests that there is a lack of integrated water security knowledge for communities that depend on water supply from snow and ice. This is due to the fact that, in these regions, there is often limited understanding of what happens ‘beyond the cryosphere’ – that is the contribution from water sources other than frozen water, such as hillslopes, wetlands, and groundwater. Communities have just always depended on melting ice as a reliable supply of water.

Emerging research is showing that the effects of global warming and climate change are enhanced in mountainous areas, where glacier-related disasters such as ice avalanches and glacial lake outburst floods are becoming more commonplace. This highlights the fact that there are likely to be serious and life-threatening implications for the millions of people who depend on mountain water supply in these regions. 

The study, published in the journal Nature Sustainability, finds that there are huge gaps in available data on how communities use water from glaciers and mountain snow in combination with other water sources. This information will be crucial in formulating management plans for sustainable water use in future, as meltwater becomes less available. The picture is especially difficult to construct, say the researchers, because of complex mountain landscapes, differences in localized weather systems and a low density of data station records.

“In mountains, there are complex interconnections between the cryosphere [snow and ice] and other water sources, as well as with humans,” said Professor David Hannah. “We need to identify the gaps in our understanding and rethink strategies for water security in the context of climate change adaptation and shifting human needs.”

The lack of data is exacerbated by low uptake of new monitoring technologies and approaches, particularly in lower income countries with limited institutional capacities. This further hampers the understanding of water use in high-altitude, data sparse regions in many parts of the world, and makes it very difficult to create models for future water management that can be scaled up accurately across watersheds.

Furthermore, the picture is complicated by uncertainties about future water needs. Information on population growth and likely adaptation to water security threats is limited, as are data on the future expansion of irrigated agriculture and hydropower, all of which will have substantial impacts on water access and allocation. In the light of these concerning gaps in understanding and knowledge, the research team have called for a fundamental rethink of the methods and technologies used to assess current water availability and to model future scenarios.

Study lead author Dr. Fabian Drenkhan conducted the research while at Imperial and now works at the Pontifical Catholic University of Peru. “The future is likely to lead to a more variable water supply and growing water demand, which is a real threat to water security in many mountain regions. Our current incomplete picture is hampering the design and implementation of effective climate change adaptation,” said Dr. Drenkhan.

“A holistic perspective based on improved data and process understanding is urgently needed to guide robust, locally tailored adaptation approaches in view of increasingly adverse impacts from climate change and other human interferences.”

What is clear is that climate change will impact the availability of fresh water over the coming decades, centuries and even millennia, making serious impacts inevitable for current communities and for generations to come. Adaptation to these changes will require comprehensive data sets and an understanding of how global warming may affect the cryosphere in order to develop management strategies that enhance water security in future. 

“Our study highlights the need for scientists to work on the ground with stakeholders. A thorough understanding of the local water security context is essential to co-produce integrated local and scientific knowledge that can support local water management decisions and adaptation strategies,” concluded study senior author Professor Wouter Buytaert.

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By Alison Bosman, Earth.com Staff Writer