A meat-free America would significantly lower greenhouse gas emissions. Credit: Pexels.

How greenhouse gas emissions would drop if all Americans went vegan

What would a society without animal agriculture look like? That’s what a pair of scientists recently investigated for the example of the United States. They found that if all Americans went vegan, there would be far fewer greenhouse emissions spewed into the atmosphere. At the same time, the researchers found that without meat or dairy, the country’s food supply would be unable to meet the population’s nutritional requirements.

A meat-free America would significantly lower greenhouse gas emissions. Credit: Pexels.

A meat-free America would significantly lower greenhouse gas emissions. Credit: Pexels.

About a quarter of the nation’s greenhouse gas emissions (GHGs) are sourced from agriculture, most of which are due to producing meat. On a global level, the livestock sector currently accounts for 14.5% of GHGs which is more than all cars, trains, and airplanes produce combined.

Meat production also promotes resource scarcity, such as poorly managed water use. Depending on where it’s grown, one pound of beef requires between 1,800 to 2,500 gallons of water. Additionally, livestock requires animal feed sourced from crops, implying more deforestation, soil degradation, water and air pollution.

“The world’s over-reliance on factory-farmed livestock to feed the growing global demand for protein is a recipe for a financial, social and environmental crisis,” says Jeremy Coller, leader of the FAIRR (Farm Animal Investment Risk & Return) group.

“Intensive livestock production already has levels of emissions and pollution that are too high, and standards of safety and welfare that are too low.”

Vegan doesn’t necessarily mean ‘green’

According to the recently published study in the Proceedings of the National Academy of Sciences, if all Americans were vegan, agricultural greenhouse gas emissions would decrease by 28 percent. However, a population of 320 million vegans still isn’t light on the environment. More cropland would be required, with negative consequences for the environment.

The two researchers, one from Virginia Tech and another from the USDA, first estimated the impact of converting all land currently used for livestock production into cropland. The transition implies far more agricultural waste is produced — things like corn stalks or potato waste which are now fed to livestock. All this excess waste would add two million tons of carbon to the atmosphere. The demand for more cropland coupled with a dwindled supply of animal manure would cause a significant uptick in fertilizer production, adding 23 million tons of CO2 per year.

It’s for this reason that an all-vegan American population would reduce greenhouse gases by only 28 percent even though animals are now responsible for 49 percent of the country’s agricultural emissions. Overall, agricultural emissions would drop from 623 million tons to 446 million tons a year. In the grand scheme of things, an all-vegan diet would only reduce total US GHG by 2.6 percentage units. What’s more, without meat in their diet, the American population runs the risk of not meeting nutritional requirements for calcium, vitamins A and B12, and a few key fatty acids.

“Overall, the removal of animals resulted in diets that are nonviable in the long or short term to support the nutritional needs of the U.S. population without nutrient supplementation,” the authors concluded.

This study shouldn’t be taken as the last word on the matter, though. Perhaps developments in the future, like synthetic meat or other protein-rich foods, could genuinely support an all-vegan American populace, as extreme as that may sound. At the end of the day, even a meat-free weekend could have a significant positive impact on the environment. Lower meat consumption would cut food-related emissions by 29%, vegetarian diets by 63%, according to a report called The Future of Food: The Investment Case for a Protein Shake Up released by FAIRR.

Already, many Americans, millennials in particular, have chosen to cut down on meat drastically. In 2014, 400 million animals were spared because people ate less meat. Twenty-five percent of US consumers decreased their meat purchases from 2014 to 2015, and meat alternative sales grew from $69 million in 2011 to $109 million in 2015. The market for protein-rich meat substitutes — food made from tofu, tempeh, textured vegetable protein, seitan, quorn and the likes — is expected to grow by 8.4% annually over the next five years.

The bottom line is that, as noble as it may sound, going vegan might not work for everyone at the population level. This is a complex task to assess which upcoming studies might elucidate further. The study also suggests that while a vegan diet significantly lowers greenhouse gas emissions, overall, the effects are not as pronounced as most people think. That’s not to say cutting back on meat isn’t very important, we have to add. To avert potentially catastrophic man-made climate change, the most important ‘low-hanging fruit’ is urgently phasing out fossil fuels.

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