Water supply at risk for nearly two billion people around the world: study

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Frozen “water towers” relied upon by close to two billion people are at risk due to factors such as climate change and population growth, according to a newly-published study.

Drafted by 32 academics — including Michele Koppes, a professor from the University of British Columbia — the study underscores the importance of what it calls “the world’s water towers” and the need to protect them.

Global News spoke with Koppes to find out more about the study — published in the science journal Nature — and how its findings relate to Canada.

What are water towers?

Water towers are essentially storage containers on earth and they’re also called watersheds, according to Koppes. 

She compares water towers to storage tanks that sit atop buildings. In this case, those buildings are mountains around the world.

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“Some of the precipitation will fall as snow or form into ice in glaciers,” Koppes said. “Those act as storage tanks.”

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These water towers essentially store fresh water, letting it go downstream through rivers to people who then use the water in low-lying areas. 

Koppes calls them a “critical piece of the global water supply,” including in Canada.

What did the study do?

The study looked at 78 mountain ranges around the world that contain fresh water stored as snow or ice.

“For each tower, we assess its vulnerability related to water stress, governance, hydropolitical tension and future climatic and socio-economic changes,” the paper said. 

Koppes said this is the first time such an analysis has taken place.

It examined the impacts of climate change on the supply of that fresh water. It also looked at the demands for that water. 

“We came up with which are the most vulnerable watersheds or water towers for each continent, and then compared them,” Koppes said.

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So what did the study find?

The study found that the most significant water towers are among the most vulnerable, and that climate change and socio-economic factors will “affect them profoundly.”

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The most vulnerable river system is the Indus River in Asia, which consists of large swathes of the Himalayas and covers parts of India and Pakistan as well as Afghanistan and China. 

It also ranked the water systems that are most relied upon for each continent.

In North America, the most relied-upon system is the Fraser River basin, followed by the Columbia River basin. 

What does this mean for Canada?

Koppes points out that Canada also has vulnerable river systems, including ones out west and the Arctic river basins. 

“We have the Columbia River, which is Canada and the U.S.,” she said, “the Fraser River system, which is B.C. and Alberta, and the Saskatchewan Nelson, which is Alberta, Manitoba [and] Saskatchewan.” 

The transboundary Columbia River serves 9 million people on both sides of the border, she said, while the Fraser and Saskatchewan river basins serve approximately three million people each. 

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Each of these has a different level of vulnerability, she said. So the impact depends on which water tower a person relies on, and where they reside along the water tower — the mountains, near the glaciers, snow and water source, or in the lowlands at the mouth of the river.

“The way it plays out is, all the glaciers and the snow packs are shrinking,” Koppes said. When the glaciers first shrink, she said, they’re “actually melting faster” — which means people might get more water at first.

“Over time, the tank is being drawn down and the glaciers continue to shrink, and so you’re going to get less water overall over a couple decades,” she said. 

Melting glaciers also increase the risks of flooding and landslides, Koppes said. 

What is next?

People need to think about how they will adjust to a world with vulnerable water towers, Koppes said.

“We need to be having the conversation in the policy realm and in the governance realm on how we are going to adapt to these changes,” she said.

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Everyone is vulnerable, with some more than others, Koppes added. 

“This is one of the big cascading effects” of climate change, she said.  

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