The production of animal-based foods is associated with higher greenhouse gas
(GHG) emissions than plant-based foods. A first-ever study in the United Kingdom compares meat-eaters, fish-eaters, vegetarians and vegans and reports the differences in greenhouse gas emissions of the groups.
The subjects were participants in an EPIC-Oxford cohort study. Diets of 2,041 vegans, 15,751 vegetarians, 8,123 fish-eaters and 29,589 meat-eaters aged 20–79 were assessed. Read the findings published in the journal Climatic Change (PDF).
Production, transport, storage, cooking and wastage of food are all contributors to GHGs. Carbon dioxide is emitted from fossil fuels used to power the agricultural machinery and transport, store and cook food. But many times more potent than the carbon dioxide emissions are the methane and nitrous oxide gases at the agricultural stage.
Animal-based products usually produce much greater emissions than plant-based products per unit weight. Methane gas is the result of the internal fermentation from digestion within ruminant livestock. Most of the nitrous oxide gases are released from tilled and fertilized soil. It may be possible to reduce these emissions with new technologies and farming practices, but major changes in both consumption choices and food wastage are necessary to make a significant difference in emissions.
In the study by diet group, not surprisingly the highest dietary GHG emissions come from the '"high meat-eating men" group while the lowest dietary GHG emissions were from vegan women. The observed mean values of meat-eaters in the order of women then men were "46 % and 51 % higher than for fish-eaters, 50 % and 54 % higher than for vegetarians and 99 % and 102 % higher than for vegans."
The U.S. Department of Agriculture had been promoting a Meatless Monday campaign encouraging cafeterias, restaurants, schools, and individuals to adopt one vegetarian meal each week. After the National Cattlemen's Beef Association and Rep. Steve King (R-IA) objected, the USDA issued a retraction saying "USDA does not endorse Meatless Monday."
After dedicating a full show to veganism and meat production, Oprah Winfrey and staff went vegan for a week and some continued the diet. Oprah announced Harpo Studios would honor Meatless Mondays with the staff reporting they felt much better and one losing 11 pounds in one week. Read posted on the Oprah site six things to know about veganism.
There are many other reasons vegetarians choose not to consume animal products but greenhouse gas emissions reduction has now been reported a scientific one.