Monday, December 9, 2019

Scientists rank world’s most important, most threatened mountain water towers

Scientists from around the world have 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, snow packs, lakes and streams, thereby supplying invaluable water resources to 1.9 billion people globally; roughly a quarter of the world’s population.
The research – published in the prestigious scientific journal Nature – provides evidence that global water towers are at risk, in many cases critically, due to the threats of climate change, growing populations, mismanagement of water resources, and other geopolitical factors. Further, the authors conclude that it is essential to develop international, mountain-specific conservation and climate change adaptation policies and strategies to safeguard both ecosystems and people downstream.
Globally, the most relied-upon mountain system is the Indus water tower in Asia, according to their research. 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. High-ranking water tower systems on other continents are the southern Andes, the Rocky Mountains and the European Alps.
To determine the importance of these 78 water towers, researchers analysed 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, Ganges-Brahmaputra
Europe: Rhône, Po, Rhine, Black Sea North Coast, Caspian Sea Coast
North America: Fraser, Columbia and Northwest United States, Pacific and Arctic Coast, Saskatchewan-Nelson, North America-Colorado
South America: South Chile, South Argentina, Negro, La Puna region, North Chile
The study, which was authored by 32 scientists from around the world, was led by Prof Walter Immerzeel and Dr Arthur Lutz of Utrecht University, longtime researchers of water and climate change in high mountain Asia.
Arun Bahadur Shrestha, who leads the River Basins and Cryosphere Programme at International Centre for Integrated Mountain Development (ICIMOD), as well as co-author of the report, said that taking forward the findings of the Hindu Kush Himalaya Assessment report, this study showcases the vulnerability of river basins that are fed by mountain catchments. The study has found the Hindu Kush Himalaya (HKH) river basins to be increasingly vulnerable, and implies the need of global attention to build resilience in these basins.
“Four out of the five most relied-upon and vulnerable water towers in all of Asia are located in the HKH region,” water and climate specialist at ICIMOD, and also a co-author Santosh Nepal said, adding, “Even when we assess at a global scale, the Indus in particular is one of the most critical and vulnerable water towers in the world. This is something the region as a whole needs to take seriously and work on addressing collectively.”
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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