New research has found that water towers, which provide water resources to 1.9 billion people globally, are at risk due to the threats related to climate change, growing populations, mismanagement of water resources, and other geopolitical factors.

The authors of the study also concluded that it is essential to develop international, mountain-specific conservation, and climate change adaptation policies and strategies to safeguard both ecosystems and people downstream.

As a part of the study, scientists from around the world assessed the planet’s 78 mountain glacier–based water systems and, for the first time, ranked them in order of their importance to adjacent lowland communities, as well as their vulnerability to future environmental and socioeconomic changes.

These systems, known as mountain water towers, store, and transport water via glaciers, snowpacks, lakes, and streams to 1.9 billion people globally—roughly a quarter of the world’s population.

The most vulnerable water tower

The research found that the Indus water tower in Asia is the most relied-upon mountain system. The Indus water tower—made up of vast areas of the Himalayan mountain range and covering portions of Afghanistan, China, India, and Pakistan—is also one of the most vulnerable.

Reliance and vulnerability

To determine the importance of these 78 water towers, researchers analyzed the various factors that determine how reliant downstream communities are upon the supplies of water from these systems. They also assessed each water tower to determine the vulnerability of the water resources, as well as the people and ecosystems that depend on them, based on predictions of future climate and socioeconomic changes.

Of the 78 global water towers identified, the following are the five most relied-upon systems by continent:

  • Asia: Indus, Tarim, Amu Darya, Syr Darya, and Ganges-Brahmaputra.
  • Europe: Rhône, Po, Rhine, Black Sea North Coast, and Caspian Sea Coast.
  • North America: Fraser, Columbia and Northwest United States, Pacific and Arctic Coast, Saskatchewan-Nelson, and North America-Colorado.
  • South America: South Chile, South Argentina, Negro, La Puna region, and North Chile.

The study assessed the importance of each water tower by looking at how much water its stores and provides. The study also examined how vulnerable these systems and communities are to a number of likely changes in the next few decades.

Unique research

The study, which was authored by 32 scientists from around the world, was led by Professor Walter Immerzeel and Dr. Arthur Lutz of Utrecht University.

“What is unique about our study is that we have assessed the water towers’ importance, not only by looking at how much water they store and provide, but also how much mountain water is needed downstream and how vulnerable these systems and communities are to a number of likely changes in the next few decades,” said Immerzeel.

“By assessing all glacial water towers on Earth, we identified the key basins that should be on top of regional and global political agendas,” Lutz added.

This research was supported by National Geographic and Rolex as part of their Perpetual Planet partnership, which aims to shine a light on the challenges facing the Earth’s critical life-support systems, support science and exploration of these systems, and empower leaders around the world to develop solutions to protect the planet.


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