Study: Vegetarian diets associated with 3x more greenhouse gas emissions

Eating lettuce emits more CO2 than bacon.

The media release is below.

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PUBLIC RELEASE: 14-DEC-2015
Vegetarian and ‘healthy’ diets are more harmful to the environment

Carnegie Mellon study finds eating lettuce is more than three times worse in greenhouse gas emissions than eating bacon

CARNEGIE MELLON UNIVERSITY

Contrary to recent headlines — and a talk by actor Arnold Schwarzenegger at the United Nations Paris Climate Change Conference — eating a vegetarian diet could contribute to climate change.

In fact, according to new research from Carnegie Mellon University, following the USDA recommendations to consume more fruits, vegetables, dairy and seafood is more harmful to the environment because those foods have relatively high resource uses and greenhouse gas (GHG) emissions per calorie. Published in Environment Systems and Decisions, the study measured the changes in energy use, blue water footprint and GHG emissions associated with U.S. food consumption patterns.

“Eating lettuce is over three times worse in greenhouse gas emissions than eating bacon,” said Paul Fischbeck, professor of social and decisions sciences and engineering and public policy. “Lots of common vegetables require more resources per calorie than you would think. Eggplant, celery and cucumbers look particularly bad when compared to pork or chicken.”

Fischbeck, Michelle Tom, a Ph.D. student in civil and environmental engineering, and Chris Hendrickson, the Hamerschlag University Professor of Civil and Environmental Engineering, studied the food supply chain to determine how the obesity epidemic in the U.S. is affecting the environment. Specifically, they examined how growing, processing and transporting food, food sales and service, and household storage and use take a toll on resources in the form of energy use, water use and GHG emissions.

On one hand, the results showed that getting our weight under control and eating fewer calories, has a positive effect on the environment and reduces energy use, water use and GHG emissions from the food supply chain by approximately 9 percent.

However, eating the recommended “healthier” foods — a mix of fruits, vegetables, dairy and seafood — increased the environmental impact in all three categories: Energy use went up by 38 percent, water use by 10 percent and GHG emissions by 6 percent.

“There’s a complex relationship between diet and the environment,” Tom said. “What is good for us health-wise isn’t always what’s best for the environment. That’s important for public officials to know and for them to be cognizant of these tradeoffs as they develop or continue to develop dietary guidelines in the future.”

CMU’s Steinbrenner Institute for Environmental Education and Research and the Colcom Foundation funded this research.

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3 thoughts on “Study: Vegetarian diets associated with 3x more greenhouse gas emissions”

  1. And exactly how many people can live long term on bacon alone? Oh ya, none, so guess what, a balanced diet of bacon and vegetables is even worse for the planet than if someone only at lettuce for sustenance. You see, the study fails to take into account all the millions of acres of crops that must be grown for the animals to eat AND then those also grown for the humans in the experiment. Gee, and these guys call themselves scientists? Sigh, the dumbing down of America. Sad to see.

  2. And exactly how many people can live long term on bacon alone? Oh ya, none, so guess what, a balanced diet of bacon and vegatable is even worse for the planet than if someone only at lettuce for sustenance. You see, the study fails to take into account all the millions of acres of crops that must be grown for the animals to eat AND then those also grown for the humans in the experiment. Gee, and these guys call themselves scientists? Sigh, the dumbing down of America. Sad to see.

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