A new UK study measures and compares the dietary greenhouse gas emissions of meat- and fish-eaters, vegetarians, and vegans.
One way to reduce your carbon footprint is to stop eating meat. I know you’ve probably heard this before, especially if you read TreeHugger, whose founder Graham Hill is a vocal proponent of “weekday vegetarianism,” but now there’s additional and interesting science to back up why a meat-free diet is such a good idea.
The journal Climatic Change has recently published the first-ever study to compare the dietary greenhouse gas (GHG) emissions of real-life meat-eaters to those who abstain from meat or choose other sources of protein. (Other studies have used modeled estimates of reduced-meat diets.) This study, which took place in the UK, compares data on the actual diets of 2,041 vegans, 15,751 vegetarians, 8,123 fish-eaters, and 28, 589 meat-eaters.
The British researchers estimated the greenhouse gas emissions for 289 types of food, a measurement that reflects the life cycle of food commodities from early production to retail. Each individual’s diet was standardized to a 2,000 kcal diet so that differences in estimated energy consumption between diet groups would not affect the end results.
They found that the highest dietary GHG emissions were found in meat-eating men and the lowest were found in vegan females. Here is how much carbon dioxide pollution (CO2e) the average male emits daily, according to different diet types. Female amounts are slightly less.
High meat-eaters (more than 100 grams per day, which defines the majority of adults in the UK and US): 16 pounds / 7.26 kilograms of CO2e
Low meat-eaters (less than 50 grams per day): 10.3 pounds / 4.67 kg
Fish-eaters: 8.7 pounds / 3.94 kg
Vegetarians: 8.5 pounds / 3.85 kg
Vegans: 6.5 pounds / 2.94 kg
These results show that an average 2,000 kcal high-meat diet has 2.5 times as many GHG emissions as an average vegan diet. Moving from a high-meat diet to a low-meat diet would reduce an individual’s carbon footprint by 920 kgC02e per year. A switch to vegetarianism would reduce it by 1,230 kgCO2e per year, and veganism would reduce it by 1,560 kgCO2e per year. By comparison, an economy return flight from London to New York adds 960 kgCO2e to an individual’s annual carbon footprint.
The meat-producing industry is a substantial contributor to GHG emissions:
“These include carbon dioxide (from fossil fuels used to power farm machinery and to transport, store, and cook foods), methane (from enteric fermentation in ruminant livestock), and nitrous oxide (released by tilled and fertilized soils).”Keep in mind, too, that methane and nitrous oxide are far more potent greenhouse gases than carbon dioxide.
It is clear that we humans are better off eating vegetables, fruits, and grains directly, instead of using them to feed animals, which is a polluting, inefficient, and roundabout way of nourishing ourselves.