Vegetarians vs. Chicken Eaters

One surprising finding of my investigation into CO2 emissions and diet, is that according to the data, eating chicken causes fewer CO2 emissions than milk and eggs do.

Comparing a lacto-ovo vegetarian diet with a "chicken lovers" diet, where both diets consist of 3,774 calories a day and the chicken lover gets 27% of his calories from chicken while the vegetarian gets 23% of the calories from milk and 4% from eggs (and both get 73% of calories from plants), a "chicken lovers" diet emits .78 tonnes of CO2 a year vs. 1.22 tonnes for an lacto-ovo vegetarian diet. Switching from eating eggs and milk to chicken saves .44 tonnes of emissions a year.

Per 100 calories, chicken causes .368 lbs of CO2 emissions vs. .620 lbs for milk and .645 lbs for eggs.

Half of the emissions for milk are due to methane coming from the cow. Taking that out of the equation (looking strictly at fossil fuel usage), chicken is slightly higher in emissions.

I am not sure why eggs have higher emissions than chicken. I guess it requires more fossil fuels to raise and collect eggs than it does to raise and collect chickens, but I can't even venture a guess as to why.

There may be moral and ethical reasons to be a vegetarian, but looking at it strictly from a CO2 emissions standpoint it is better to go with the chicken and pass on the milk and eggs.