A peer-reviewed study published in Nature Climate Change this week points a finger at food production, claiming that 75% of the study’s predicted warming between now and 2100 is caused by foods that are high sources of methane.

Ruminant meat, dairy and rice production are the groups a new study points to as major culprits of emissions. Using dietary recommendations provided by the Harvard Medical School, which focus on reduced meat intake, promoting a protein-rich diet with less saturated fat and cholesterol and reducing red meat consumption to one serving per week, the study found that if these dietary changes were implemented globally, warming due to food consumption could be decreased by 0.19 degrees C by the end of the century.

The study also found that sustaining current dietary patterns worldwide throughout the rest of the century could amount to nearly 1 degree °C of additional warming beyond today’s level of ~1  degree C above pre-industrial times.

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LOOK TO DEVELOPING COUNTRIES

University of California-Davis Professor and Air Quality Extension Specialist Frank Mitloehner said a single degree increase is significant, but inefficient developing countries are responsible for 80% of greenhouse gas (GHG) emissions globally. He said he does not believe the animal-sourced food produced will contribute a 1 degree increase by the end of the century. The world, he said, is trying to keep additional warming below a 1.5-to-2-degree increase, making livestock production contributing 1 degree would be significant, but unlikely.

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Mitloehner said developing countries are “where the music plays” when it comes to emissions. The U.S. dairy cow herd is 9 million head and in India alone, there are 300 million head.

As for comparing the effects on emissions of the high-powered dairy ration fed in the U.S., compared to a developing country, he said dairy cows in developing countries receive an inadequate diet, the cows are of the lowest genetic merit, lack veterinary care, and suffer very low reproductive rates. Once retired from milking, Indian dairy cows are turned out to pasture and never slaughtered per religious beliefs. From that point, the animal lives without producing milk, but still producing emissions.

“To tell people who don’t have enough nutrients now, that they need to eat even fewer nutrient-dense foods, I think is something I don’t want to be a part of,” Mitloehner said.

In the U.S., he said if all citizens participated in Meatless Monday, the carbon footprint would be reduced by 0.3%. If all U.S. citizens adopted an entirely vegan diet, the carbon footprint of the country would be reduced by 2.6%.

“What I’m telling you is by far, the greatest source of GHG emissions in a country like the U.S. is the use of fossil fuels, oil, coal and gas,” he said. “What we eat makes up a relatively small percent of the carbon footprint of the U.S.”

In contrast, livestock production in developing countries makes up the majority of their emissions due, he said, to the production inefficiencies. While he said the situation in 2100 is completely unknow at this point, the only way livestock production would contribute more to the overall emissions is if the entire vehicle fleet were electrified and by reducing transportation’s footprint, agriculture’s footprint became a higher percentage of the overall emissions numbers.

FOOD WASTE CONTRIBUTES

Consumer-level food waste, he said, is a significant problem in the U.S. and one that contributes to emissions. It isn’t solely an American problem, though, it is a problem in other countries similar to the U.S. and developing countries as well. He said 40% of the food globally goes to waste primarily in the form of perishable food like fruits and vegetables going uneaten before spoiling. Mitloehner said 60% of produce goes to waste and animal-sourced foods at 10-20%.

“This is the main contributor to environmental harm from our food system — the food we don’t eat because it’s wasted,” he said.

He said the “sell by date” stamp on food contributes to food waste because consumers often assume the sell by date is an expiration date and throw it away. Another contributor is consumers’ unwillingness to purchase or use food, produce especially, that isn’t visually perfect. He said when grocery stores throw out food that has passed its sell by date, it is often not donated for fear of a lawsuit resulting from alleged sickness as a result of eating food past its sell by date. Enormous portion sizes in restaurants, he said, is also a major factor contributing to food waste.

Mitloehner said the most important takeaway for livestock producers from climate studies is confidence in U.S. producers leading the world in efficient livestock production.

The majority of the land used for beef and dairy production in the U.S. is marginal and unsuitable for crop production, making the best use of those marginal lands. Additionally, he said cattle make use of food waste from other production as part of their ration that is eventually upcycled into high-quality protein by beef and dairy cows alike.

Upcycling, he said, is possible through ruminant animals grazing and eating cellulose, a substance not digestible by other species, including humans, and converting it into food with high nutritional values for humans.

“There’s nobody else who produces as efficiently as we do,” he said.