Global water security risks: The impact of upwind factors

Securing the world’s water supply has emerged as a critical challenge in the face of evolving environmental and governance conditions, according to research from Stockholm University

The study, published in Nature Water, introduces a new approach to assessing global water scarcity risks by emphasising the often-overlooked factors upwind of water sources.

Origins of moisture

Traditionally, water security assessments have focused on the immediate area where rain falls and collects in aquifers, lakes, and rivers. However, the study led by Fernando Jaramillo, associate professor in physical geography, sheds light on how crucial it is to consider the origin of moisture that travels through the atmosphere before precipitation occurs.

“This upwind moisture is commonly overlooked when assessing water availability,” explains Jaramillo. “Water supply originates beforehand, with moisture evaporated from land or in the ocean travelling in the atmosphere before falling as rain.”

The research analysed 379 hydrological basins worldwide, revealing startling insights. By adopting an upwind perspective, which factors in where evaporated water originates, the study found that global water requirements facing very high risk could increase by nearly 50% compared to traditional assessments.

Changes in land use

Changes in land use such as deforestation upwind can reduce moisture levels, affecting rainfall downstream and heightening water security risks.

“For coastal countries such as the Philippines, most of the rain comes from the sea, which means that land-use changes pose very little risk to water security. Rainfall in inland countries such as Niger, on the other hand, comes mainly from moisture that evaporates in neighboring countries such as Nigeria and Ghana .” adds Jaramillo.

The study highlights the need for international cooperation in managing upwind moisture sources to mitigate potential water-related tensions. Lan Wang-Erlandsson, co-author and researcher at the Stockholm Resilience Centre, emphasises the importance of cross-border collaboration in environmental regulation.

Environmental regulations

“It is not possible to ignore the interdependence between countries. In the end, all water is connected, so we should not only mind how we manage our water resources within a region or country but also how our neighboring countries do, ” Wang-Erlandsson explains.

The findings call for a shift in how we approach water security globally, moving beyond national borders to consider transboundary water flows and cooperative management strategies.

“We hope that the findings of this study can help identify where and to whom cooperation strategies and efforts can be directed to mitigate the causes of water-related tensions, including atmospheric water flows in transboundary decision-making and water governance frameworks,” concludes Jaramillo.