Planetary Consequences of Animal Based Diet

There is a significant difference in the planetary footprint of a person eating a plant-based diet compared to a person eating an animal-based diet. You can determine the average caloric efficiency of foods by comparing the edible energy output to the fossil fuel. Using the equation =100 X (edible energy output/fossil fuel energy input), the average caloric efficiency of animal-based foods is 10-15% while the average caloric efficiency of plant-based foods is 220%. It is possible to use this information to quantitatively analyze the differences in animal v.s. plant based diets with the equation, E = cd (/e + (1-)/f). e represents the caloric efficiency of a particular animal-based diet (red meat, lacto-ovo, etc.) and f represents the caloric efficiency of plant-based diets. c represents the total U.S. caloric consumption of one person per year (3774 kcal/day X 365 day/year = 1,377,510 kcal/year). Using the economy-mean conversion, d represents how much CO2 equivalent is emitted per unit of energy (2.778 X 10^-7 ton C02/kcal). Thus, cd= 0.383 ton C02 –eq/yr (the annual CO2 emissions of a person consuming 3774 kcal/day). To find the difference between animal and plant based diets, we can subtract Evegan from E which gives us cd(1/e – 1/f). Then, we can compare different diets characterized by specific e and f values (see Figure 1). Using this equation, we can determine that the average meat eater (27.7% of calories from meat) produces .701 more tons of C02 than the average plant eater.*

The average person living in the United States has a planetary footprint of 18-25 tons of green house gases per year. Around 1/5th of this output (3-4.5 tons) comes from eating. Besides driving an environmentally friendly car, it is difficult to significantly decrease one’s greenhouse gas emissions. For example, one person refusing to buy a certain brand of jeans is not going to greatly affect the commercial sector. Thus, choosing a vegan diet is one of the most significant ways a person can decrease their planetary footprint. In addition,