Is the Earth running out of water? Global water security is complicated

Global water security is under threat due to a combination of extreme weather events and increased demand from booming populations. A recent study from the Utrecht University has investigated the relationship between water use by various sectors and the prevalence of droughts and heatwaves.

“Water use for various sectors (e.g. irrigation, livestock, domestic, energy and manufacturing) is increasing due to a growing global population and economic development,” wrote the study authors. 

“Additionally, increases in frequency and severity of droughts, heatwaves and compound drought-heatwave events, also lead to responses in sectoral water use and a reduction in water availability, intensifying water scarcity. However, limited knowledge exists on the responses in sectoral water use during these hydroclimatic extremes.”

Water use under extreme conditions

The research stands out as the first-ever global investigation focused on the complex issue of water use under extreme conditions.

Study lead author Gabriel Cardenas Belleza defines “sectoral water use responses” as the modifications or stability in water consumption practices by different sectors under the influence of droughts, heatwaves, or a combination of these extreme events.

Studying water security

The comprehensive analysis was focused on sectoral water use data from the last three decades, including usage at global, national, and local scales.

“We focused on the water used by various sectors, namely irrigation, livestock, domestic, energy and manufacturing, because we expected particular responses to the occurrence of different extreme events, ” explained Belleza.

Crucial observations

The study revealed that extreme weather events have substantially altered water consumption habits worldwide over the last thirty years. However, these alterations are not uniform across sectors or regions.

“Socio-economic factors and public water management plans strongly influence water use responses, and even more so during extreme events. For instance, while Western continental United States decreases its water use during extremes, the central US increases it,” said Belleza.

Among the sectors analyzed, the domestic and irrigation sectors often get prioritized when it comes to water utilization. However, the findings indicate a shift in favor of the domestic sector when water usage is restricted during extreme events.

Compound weather events

Heatwaves and combined drought-heatwave events were found to exert a greater influence on water consumption than droughts alone.

“Heatwaves and compound events can lead to higher water use as a consequence of the temporary increase in water demand under high temperatures, which can still be satisfied due to the short duration of such extremes, compared to longer-lasting events like droughts,” said Belleza.

Study implications 

The study sheds light on the relationship between extreme weather patterns and global water consumption practices. 

The researchers noted that given the future threats to water availability and the limited accessible information of water use, there is an urgency to collect more data of sectoral water use for improved assessments of water scarcity under these extremes.

“Our research provides a first step to evaluate multi-sectoral water use behavior during extremes,” said Belleza. “However, more local-scale information from data-scarce areas, like Africa and parts of Asia and South America, is needed to better understand sectoral water use behavior and improve water management strategies.”

The research is published in the respected journal Environmental Research Letters.

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