Humanity now consumes around 5.6 trillion m3 of green water and 1.2 trillion m3 of blue water each year to grow crops. If this total volume (6.8 trillion m3) were a lake, it would be the sixth largest in the world.
The statistics have been published in a new research paper in Nature Food, which also showed crop water consumption increased by 9% for 46 agricultural crops between 2010 and 2020.
Growth in the blue water footprint is particularly concerning, as it intensifies pressure on already water-stressed river basins like the Indus, Ganges or Yellow, which provide food security for many hundreds of millions of people.
The study “highlights the growing demand for water resources in agriculture, emphasising the need for sustainable water-management practices to support both rain-fed and irrigated agriculture under increasing pressure from global food demand”.
Regionally, the most water consumption occurs in Asia, the Americas and Africa; among crops, the largest consumers are rice, maize, wheat, soybeans and palm oil.
The expansion of harvested area is an important driver for the increased water consumption. This expansion has also led to deforestation, especially in the global south, they explained. Intensification on existing lands, due to factors such as increased nutrient application or multiple cropping practices, will have “an important influence”, they added.
Between 2010 and 2020, the total crop water footprint increased by 9%, primarily owing to the expanded harvested areas of crops such as maize, soybeans, groundnuts, sugarcane and cassava in response to rising global demands for food, animal feed and biofuels.
Their modelling, like other water footprints, has its limitations, which underscores the need for transparency. Corporate accounting for water use must also be improved, with risks identified and investors offered full transparency of businesses’ exposure to these.
The researchers also painted a bleak picture of what is to come. Farming and food will compete more fiercely with different sectors for access to limited water resources, which puts food security at increased risk.
There are ways to limit water consumption, though. Producing more food with less water (‘more crop per drop’), the cultivation of less water demanding crops in water-stressed river basins, the shift to more plant-based diets among affluent populations and the reduction of food losses and waste along the supply chain, are among the opportunities listed by the researchers.
