In tandem, two strategies could lower water consumption by 28% and ensure better water supply for more than 600 million people.

By 2050, the Earth’s population is expected to exceed 9 billion people. We will need 50%–70% more food than is produced today, and without significant changes, many—if not most—people will be affected by water scarcity. Climate change will further strain water supplies in many regions, making it even more difficult to ensure a sustainable food supply for a soaring population.

Scientists have suggested many ways to use water more efficiently during the food production process. Although no single strategy holds all the answers, combining them could meet humanity’s future food needs sustainably. For the first time, researchers have now assessed the use of two promising approaches in tandem: shifting from animal- to plant-based diets and reducing food loss.

Studies show that eating fewer animal-based products could reduce water use since animal production uses more water than crops do. In addition, reducing the amount of food that’s lost or wasted at various points in the food supply chain could feed about 1 billion extra people while simultaneously reducing water use.

Building on these studies, Jalava et al. find that the combined effects of diet change and reduced food loss are complex. In some regions, for example, less food loss is associated with animal products than with plant-based foods, even though more water is needed to make animal products.

To tackle the problem, the researchers considered several diet scenarios that cut down on meat and other animal products, like dairy, while still maintaining human health. They also considered the effects of reduced food loss, including losses during production as well as after distribution. When combined, these scenarios result in significantly less water consumption worldwide. In some places, reducing losses is more effective under a changed diet, supporting a tandem approach.

The team honed in on a diet that cuts down the maximum percentage of protein obtained from animal products (except fish) by 25%. This would be easier to implement than a more extreme reduction. If food loss were also reduced by 50% at every step of the food supply chain, the researchers found, this diet would reduce global water consumption by 28%.

Changing diets worldwide would be a daunting task. Enjoyment and tradition play a big role in what people eat and how much. Food loss reduction would also be a challenge, but economic incentives could make it an attractive goal at certain steps in the supply chain.

Despite the challenges, the potential benefits of diet change and food loss reduction are significant. The researchers call for further studies that explore their impact while incorporating such additional factors as food preferences, trade partnerships, and finer-scale water availability data. (Earth’s Future, doi:10.1002/2015EF000327, 2016)

—Sarah Stanley, Freelance Writer

Citation: Stanley, S. (2016), Eating less meat, wasting less food could save water worldwide, Eos, 97, doi:10.1029/2016EO051195. Published on 27 April 2016.