Water shortage: a problem much more serious than expected

Global water shortages are a much more serious problem than previously estimated, and could affect an additional 3 billion people in 2050, due in particular to nitrogen pollution linked to fertilizers, researchers concluded in a study published on Tuesday.

The scientists, based in the Netherlands and Germany, analyzed river basins and sub-watersheds around the world to measure not only the quantity of water – as is usually the case – but also its quality.

According to their models, the results of which are published in the journal nature Communications, the number of sub-basins affected by the shortage is greater than estimated so far and will be greater in the future.

“We have shown that water scarcity will increase in the future, and not just because of climate change and increased withdrawals,” says Benjamin Budersky of the University of Potsdam, one of the co-authors. “We also show that the continuing increase in agricultural production, as well as untreated wastewater, also leads to a shortage of clean water,” he emphasizes.

Nitrogen, found particularly in some fertilizers, contributes to green algae blooms, threatens marine life and harms water quality.

“The number of subbasins facing severe shortages doubled in 2010 and may triple in 2050 according to our assessment of clean water shortages, compared to assessments that look at water access only from a quantitative perspective,” the authors write in their study.

They consider that in 2010, 2,517 sub-basins in the world were facing this problem, compared to only 984 according to traditional quantitative assessments. The number could rise to 3,061 in 2050.

Up to 3 billion additional people are at risk of being affected by water shortages due to nitrogen pollution, particularly linked to the use of fertilizers in intensive agriculture.

The authors therefore recommend reducing their use, taking care to avoid undesirable impacts on the food supply by favoring some alternative crop varieties or by better calibrating the use of fertilizers.

“The decline in water access could be halted, and even reversed to some extent, if more efficient use of fertilizers and more plant-based diets were adopted, and if we could connect a greater proportion of the world's population to water treatment facilities,” says Benjamin Budersky.