Is Vegetarianism Worth It?
It is an article of faith among many of those seeking a low-carbon lifestyle that consuming less meat and more plant-based food will have a large impact on one's toll on the planet. (See, for example, my own "Old MacDonald's Carbon Footprint.") But a new study published in the American Journal of Clinical Nutrition complicates that tidy narrative. Researchers analyzed the eating habits of 2,000 French adults alongside lifecycle studies of those diets' various components. When judged by weight alone, meat came out far more carbon intensive--14 times as much as produce. But when the diets are weighed by grams of CO2 emitted per calorie, the gap turns out to be much narrower--only 3 times as much. The energy content of meat is very high--one of the reasons for its enduring popularity. Fruits and vegetables require fewer carbon inputs to produce, but you have to eat a lot more of them to get the same energy content.
The most greenhouse gas - 857 grams - was still emitted to produce 100 kcal of meat, but it was only about three times the emissions from a comparable amount of energy from fruit and vegetables.
Greens also ended up emitting more gas for the calories than starches, sweets, salty snacks, dairy and fats. It was also about as much gas as pork, poultry and eggs.
And when [senior author Nicole] Darmon and her colleagues looked at what people actually ate to get a certain amount of energy from food every day, they found that the "highest-quality" diets in health terms - those high in fruit, vegetables and fish - were linked to about as much, if not more, greenhouse gas emissions as low-quality diets that were high in sweets and salts.
Of course, a plant-based diet one third as carbon intensive as a meat-based one is still a laudable thing for many reasons. (But do read, however, former farmboy Mr. Green's stirring defense of meat). One lesson here seems to be that it is very easy for us to underestimate our carbon impact on the planet--especially when as many as two-thirds of self-professed vegetarians are eating burgers on the side. In fact, this Yale study puts the number of true vegetarians in the U.S. at 0.1%. Let she who abjures bacon cast the first stone.
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