Plant-heavy ‘flexitarian’ diets could help limit global heating, study finds

<span>A global shift toward plant-heavy diets could help restrict heating to 1.5C, researchers find.</span><span>Photograph: KateSmirnova/Getty Images/iStockphoto</span>
A global shift toward plant-heavy diets could help restrict heating to 1.5C, researchers find.Photograph: KateSmirnova/Getty Images/iStockphoto

A global shift to a mostly plant-based “flexitarian” diet could reduce greenhouse gas emissions and help restrict global heating to 1.5C, a new study shows.

Previous research has warned how emissions from food alone at current rates will propel the world past this key international target.

But the new research, published in the Science Advances journal, shows how that could be prevented by widespread adoption of a flexitarian diet based around reducing meat consumption and adding more plant-based food.

“A shift toward healthy diets would not only benefit the people, the land and food systems,” said Florian Humpenöder, a study author and senior scientist at the Potsdam Institute for Climate Impact Research, “but also would have an impact on the total economy in terms of how fast emissions need to be reduced.”

Taxing or putting an explicit price on greenhouse gas (GHG) emissions to reflect their true economic costs could incentivize polluters to reduce their carbon footprints, though governments have had little success in attempts to bring in such policies.

The researchers found that adopting a flexitarian diet could lower methane and nitrous oxide emissions from agriculture and lower the impacts of food production on water, nitrogen and biodiversity. This in turn could reduce the economic costs related to human health and ecosystem degradation and cut GHG emissions pricing, or what it costs to mitigate carbon, by 43% in 2050.

The dietary shift models also show limiting peak warming to about 1.5C can be achieved by 2045 with less carbon dioxide removal, compared with if we maintain our current diets.

“It’s important to stress that flexitarian is not vegetarian and not vegan,” Humpenöder says. “It’s less livestock products, especially in high-income regions, and the diet is based on what would be the best diet for human health.”

Related: How do you get enough protein in a climate-friendly way?

In the US, agriculture accounts for more than 10% of total GHG emissions. Most of it comes from livestock. Reducing meat consumption can free up agricultural land used for livestock production, which in turn can lower methane emissions. A potent greenhouse gas, methane is mainly expelled from cows and other animals raised for livestock. Animal production is the primary contributor to air quality-related health impacts from US food systems.

“This paper further confirms what other studies have shown, which is that if we change our diets to a more flexitarian type, we can greatly reduce greenhouse gas emissions,” said Jason Hill, a professor in the University of Minnesota’s department of bioproducts and biosystems engineering.

According to the study authors, one way to achieve a shift toward healthier diets is through price-based incentives, such as putting taxes on the highest-emitting animal products, including beef and lamb. Another option is informing consumers about environmental consequences of high meat consumption.

“The overall food system has many players,” said Hill. “There’s the producers, the consumers who choose what to eat, and in the US especially, the government, which supports the type of agriculture that leads to excess production of red meat.”