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How to secure global water supplies as the planet heats up

October 12, 2023

Climate change is having disparate effects on global water cycles, with floods in some regions and droughts in others. Besides phasing out fossil fuels, responding to this requires improved cooperation on water data.

Water gushes and foams as it is released from a giant dam in Australia. Around the dam are trees and rolling hills.
Water is released from Wyangala dam in Australia in 2022Image: Nathan Laine/abaca/picture alliance

Water security for millions of people is at risk as climate change and human activities throw hydrological cycles into chaos, according to a new report from the World Meteorological Organization published on Thursday.

So far, a lack of data has hampered monitoring of the increasingly erratic water cycle that is connected to floods and droughts, which both impact drinking water supply and water available for crops. And that has impacted the development of early warning systems that would help save lives. But this may be starting to change, according to the authors of the WMO's second State of Water Resources report.

"For us to be able to adapt, to plan, to even mitigate climate change, we need information on how our water resources are right now and how they are going to change," said report coordinator Sulagna Mishra, a scientific officer at the WMO.

"Hydrological data is very sensitive to downstream countries, so it plays a role also in geopolitics," Mishra told DW, adding that  ​​​​​countries are often very wary of sharing information on water supplies.

Revolutionizing water data sharing

Data was also limited by a lack of monitoring in certain regions, including Africa, the Middle East and Asia were particularly hit by insufficient observational data.

But progress is being made on this front. The 2021 inaugural report relied on data from just 38 stations compared to more than 500 stations in 2022. And where on-the-ground data was not available, researchers were able to draw on remote-sensing and other methods.

"The openness of the members started growing once they saw the potential of this kind of analysis," Mishra said. "I think it's going better."

 People wade through flooded roads In Bayelsa, Nigeria
Nigeria suffered its worst floods for decades in 2022Image: Reed Joshu/AP/picture alliance

In a statement, WMO Secretary-General Petteri Taalas said the report was "a call to action for more data sharing to enable meaningful early warnings and for more coordinated and integrated water management policies that are an integral part of climate action."

The WMO also called for further funding to help fill the monitoring gaps and provide a clearer overall picture of the world's water resources and allow policymakers to focus on hotspots of water problems and redirect efforts.

How the world's water cycle is changing

More than half of global catchment areas had unusual levels of water flowing in from their source rivers in 2022, the report found. Most were drier than average, but some were uncharacteristically full. (See infographic and click on the dots for more information).

Low levels in rivers and erratic rainfall connected to the burning of fossil fuels caused problems across the world in 2022.

The USA faced transportation difficulties on the depleted Mississippi, while hydropower production in South America's La Plata river basin — encompassing parts of Bolivia, Uruguay, Brazil, Paraguay and Argentina — was hampered by low river flows. Paraguay's water supply was interrupted several times in 2022 due to shortages.

Drought in Europe meanwhile resulted in low water levels that made transport difficult in rivers such as the Danube and the Rhine, while French nuclear power stations faced production issues due to a lack of cooling water. Nuclear power accounts for two thirds of France's energy generation.

The Horn of Africa suffered through its third consecutive year of low-rainfall in 2022 leading to a severe drought affecting at least 36.1 million people and leaving 4.9 million children acutely malnourished.

Too much water triggers disasters

Drought across many regions of the world was not the only impact of disrupted hydrological cycles. The report also noted areas that had been overwhelmed by water.

Above-average levels in the Niger Basin and coastal areas of South Africa, for example, were linked to major flood events in 2022.

And more than 1700 people lost their lives in a mega flood in Pakistan's Indus River Basin last summer. The event, which caused more than US$ 30 billion in economic losses, was triggered by an earlier heatwave that melted glaciers, followed by severe monsoon rains which swelled river levels to disastrous levels. These conditions were made far more likely due to climate change, according to the World Weather Attribution research group.

People play on the bed of Yangtze River revealed by the drought in Wuhan in central China's Hubei province
China's Yangtze River had unusually low levels of waterImage: PENG NIAN/Avalon/Photoshot/picture alliance

Several flood events were also reported in East Australia's Murray–Darling river basin, New Zealand, and Canada's Winnipeg basin.

Crucial consequences: How global glaciar melt affects water

The report also assessed the global cryosphere — frozen water supplies in snow and ice.

It found a notable decrease in snow cover in the high mountain region in Asia known as the "third pole," shortening the snowmelt period and swelling lakes fed by glacial melt. 

This in turn affected water levels in the Indus, Amu Darya, Yangtze and Yellow River basins — across Central Asia, Southern Asia and China, affecting water supplies for almost 2 billion people.

The European Alps suffered similarly, with reduced snow cover and glacier loss, while key watersheds in parts of the South American Andes reported below-average conditions, especially on the Argentinean side, leading to sustained water restrictions in populous urban centers.

Improving early warning for water-related disasters

According to UN Environment Program, over 90% of natural disasters are water-related, including drought and aridification, wildfires, pollution and floods.

The WMO has been tasked with leading efforts to develop early warning systems for everyone by 2027. Just half of the world has access to early warning systems, with a notable lack in Africa, small island states and developing countries.

Aside from reducing human-caused carbon emissions, early warning systems are key to avoiding the worst damage from water system instability, according to researchers.

"We need to have better prediction methods to be able to predict these events and adapt ourselves so that we don't lose so many lives and so we are much better prepared," Mishra said.
Edited by: Tamsin Walker