Gases are produced as natural byproducts of various activities on earth. These gases, including carbon dioxide, methane, and nitrous oxide, rise up into the atmosphere. There, they hover over the earth like a chemical blanket, threatening to warm up the planet to an unprecedented degree and permanently change our climate patterns. Because these gases contain warmth, they are collectively known as "greenhouse gases."
Some greenhouse gases are produced during the burning of wood, solid waste, and fossil fuels such as coal, oil, and natural gas. Other greenhouse gases are released as a result of industrial activities, such as the manufacture of construction materials.
The agricultural industry produces greenhouse gases whenever livestock produce methane, foods are processed, fertilizers and pesticides are used, or when food is transported to packaging plants and markets. In fact, food production is thought to contribute up to 30 percent of all greenhouse gas emissions.
Because producing animal foods such as meat, poultry, fish, eggs, and dairy products results in higher greenhouse gas emissions than fruits, vegetables, grains, and other plant foods—up to 15 times more—a plant-based diet has always been assumed to be as good for the planet as it is for the people who inhabit it. Not so, according to a French study published in the American Journal of Clinical Nutrition.
Plant-Based Diets Produce Greenhouse Gases, Too
The researchers rated the nutritional quality of the diets of nearly 2,000 adults, with high-quality diets containing more plant-based foods and fewer sweets and salty snacks, and low-quality diets containing more processed snack foods and fewer fruits and vegetables. When the diets were correlated with food-related greenhouse gas production, both animal- and plant-based diets were associated with significantly higher emissions than the diets that contained more junk foods.
Growing plant foods doesn't produce nearly as much greenhouse gas as growing livestock, but when all aspects of production and delivery are factored in, including the use of farm equipment and supplies, as well as food processing, packaging, and transportation, the gap narrows. It turns out livestock (and animal-based foods) are responsible for only three times the amount of greenhouse emissions as plant foods, much less than previously estimated.
There's at least one possible explanation for this. All food is fuel for your body. If you consume, say, 1,500 calories a day, the type of foods you choose will determine how much food you actually eat to reach that calorie level. Since fruits and vegetables tend to be lower in calories than sugar- and fat-laden foods, you would need to eat more plant-based than animal-based foods to to obtain the required 1,500 calories. As with any type of industry, the more of the product produced, the more emissions result.
The Bottom Line
"Putting food on the shelf, whether it is plant- or animal-based, creates a variety of waste products and chemicals that are returned to the envirnoment," says Eugene S. Talkle, Climate Scientist at Iowa Sate University in Ames. "Finding the diet with the least impact requires a full accounting of all the byproducts created and all the energy used along the way."
Sources:
Eugene S. Takle
Director, Climate Science Program and Professor of Atmostpheric Scienc
Iowa State University.
Environmental Protection Agency. "Greenhouse Gasses Overview." Web. Page updated 21 June 2013. Page accessed 5 July 2013.
http://www.epa.gov/climatechange/ghgemissions/gases.html
Scott-Thomas, Caroline. "Plant-Based Diets: Healthy for People, But What About the Planet?" FoodNavigator.com Web. 15 Feb 2013. Page accessed 5 July 2013. http://www.foodnavigator.com/Science-Nutrition/Plant-based-diets-Healthy-for-people-but-what-about-the-planet/
Vieux, F. et al. "High Nutritional Quality is Not Associated with Low Greenhouse Gas Emissions in Self-Selected Diets of French Adults." American Journal of Clinical Nutrition. 30 Jan 2013. doi:10.3945/ajcn.113.035105. Page accessed 5 July 2013. http://ajcn.nutrition.org/content/early/2013/01/30/ajcn.112.035105
