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September 18, 2019

Can Going Vegan Save the Planet?

 |  By: Jim Dickrell

A team of scientists from John Hopkins University claims switching to all vegan-diets across the globe would reduce the per capita greenhouse gas (GHG) footprint of food production by 70%.

Going to just one meatless day per week would cut the average American’s greenhouse gas emissions by 156 pounds per year, says Keeve Nachman, an assistant professor in the department of Environmental Health and Engineering at John Hopkins. That would be equivalent of reducing the annual mileage of a typical passenger vehicle by 174 miles per year, he says.

In other words, if individuals reduce their driving by less than ½ mile per day, they would achieve a greater GHG footprint reduction than going to meatless Mondays. And that points to the magnitude of switching diets compared to reducing fossil fuel use.

Switching from an omnivore diet to an all-vegan diet would reduce an individual’s GHG footprint by 0.8 metric tons of carbon dioxide equivalent (CO²e), says Frank Mitloehner, an associate professor involved with environmental studies at the University of California-Davis. That’s half the carbon footprint of one international flight, he says.

Going to an all-vegan diet would reduce emissions by 2.6%, says Mitloehner. “But that would come at a price,” he says.

American agriculture would not be able to produce all the nutrients needed by consumers in the United States if everyone ate an all vegan diet. “That’s a price I’m not willing to pay,” says Mitloehner.

The other problem is that environmental activists take global emissions numbers and then apply it to the United States. For example, the United Nation’s Food and Agriculture Organization estimates that animal agriculture contributes 15% to GHGs globally.

In the United States, however, with it far more efficient agriculture, animal agriculture contributes just 3.9%. Dairy’s contribution is 1.37%. Transportation, electrical generation and industry contribute 79% of U.S. emissions, estimates the U.S. Environmental Protection Agency.

Since 1950, notes Mitloehner, the U.S. dairy industry has reduced its GHG footprint by two-thirds. Increasing per cow productivity has allowed the U.S. dairy industry to shrink its GHG emissions to historic lows.

For example, the average U.S. dairy cow now produces 23,000 lb of milk per year. In Mexico, it takes 5 cows to produce that amount of milk. In India, it takes 20 cows. “All of this nuance gets lost when global averages are used,” Mitloehner says.

Dairy can also be part of the solution to reducing GHGs. One way is to capture methane produced by manure and convert it to liquid natural gas. This gas is actually a carbon negative fuel because it can be used in trucks and buses, replacing diesel fuel which has a high GHG footprint, he says.

For more from Mitloehner, click here.