People who follow a plant-based diet account for 75 percent less in greenhouse gas emissions than those who eat more than 3.5 ounces of meat a day, and a vegan diet also results in significantly less harm to land, water and biodiversity, according to new research from the University of Oxford. (Photo Credit: Steven May/Alamy)

While the link between animal agriculture and environmental harm is well established, earlier studies used scientific modeling to reach those conclusions. By contrast, the Oxford research drew from the actual diets of 55,500 people — vegans, vegetarians, fish-eaters and meat-eaters — in the United Kingdom and used data from some 38,000 farms in 119 countries.

The peer-reviewed study, led by Peter Scarborough, a professor of population health at Oxford, was published on Thursday in the journal Nature Food.

If meat eaters in the United Kingdom who consumed more than 3.5 ounces of a meat a day (slightly less than the size of a quarter pound burger) cut their intake to less than 1.7 ounces a day (roughly the amount of a single McDonald’s meat patty) it would be the equivalent of taking 8 million cars off the road, Dr. Scarborough said.

The study found that, compared to meat-heavy diets, vegan diets resulted in 75 percent less land use, 54 percent less water use, and 66 percent less biodiversity loss. A vegan diet avoids all animal products, including meat, eggs and dairy.

In terms of greenhouse gas emissions, people who ate more than 3.5 ounces of meat daily accounted for 22.5 pounds of carbon dioxide emissions a day due to, among other variables, the farming of livestock and land used to grow animal feed. People who ate less than 1.7 ounces of meat accounted for about half that amount, or about 11.8 pounds of carbon dioxide emissions, while fish eaters accounted for 10.4 pounds of carbon dioxide a day, and vegetarian diets produced 9 pounds of carbon dioxide daily. Vegan diets had the lowest totals, accounting for 5.4 pounds of carbon dioxide a day.

There were parallel effects on freshwater pollution and biodiversity loss by diet type. In terms of land and water use and effects on species’ extinction, vegetarians, fish eaters and low meat diets had similar results.

The study also found that vegans and vegetarians were on average younger than fish and meat eaters.

Dr. Scarborough said while critiques of plant-based diets often highlighted environmental effects of select vegan foods, such as the volume of water required to produce almond-milk, the new research showed that plant-based diets had far less of an environmental toll than animal-based ones, regardless of how the food was produced.

In the Oxford study, meat was defined as all land animals. Earlier research has found that organic cow, chicken and pig meat production is just as harmful to the climate as conventional livestock farming.

“What our work says is even in the worst-case scenarios, the environmental footprint of not only vegan diets but low meat diets are much, much better than high meat consuming diets,” Dr. Scarborough said.

“This reinforces the message that the amount of meat we consume is strongly related to our environmental footprint,” Dr. Scarborough said. “Small changes from being a high meat eater to a low meat eater can make a huge difference in environmental impact.”

Globally, the food system is responsible for about one-third of planet-heating emissions, 70 percent of freshwater use and 78 percent of freshwater pollution. To slow the worst climate effects, the United Nations has called for a drastic reduction in meat consumption.

The Oxford study was funded by the Wellcome Trust, an independent global charity based in London focused on health research.

Cara Buckley is a climate reporter who focuses on people working toward solutions and off-the-beaten-path tales about responses to the crisis. She joined The Times in 2006 and was part of a team that won a Pulitzer Prize in 2018 for reporting on workplace sexual harassment. More about Cara Buckley

Eating and Cooking Choices That Help the Planet

The food we consume is responsible for considerable amounts of panet-warming greenhouse gases. Luckily, there are ways to minimize that effect.

• Start by analyzing the extent to which your eating habits contribute to climate change. Take our quiz to figure it out.
• Next, expand your knowledge on the subject.
• Consider phasing out that gas stove and switching to induction cooking, which is less polluting and better for your health. Wirecutter can help you choose the right model for you.
• Sign up for one of the many apps that allow customers to buy leftover food from restaurants and grocery stores at reduced prices.
• Try climate-friendly ingredients like kelp (and even bugs) or explore cuisines that are gentler on the planet.
• Embrace this simple truth: You don’t need to become vegan to reduce your meat and dairy intake.
• Once you are done feasting, don’t forget about what’s left behind. These tips will help you reduce food waste and repurpose leftovers creatively.