I was discussing with a friend of mine the other day the environmental impact various kinds of meat. I read an article in Scientific American that showed the greenhouse gas produced in the production of various kinds of food. Half a pound of beef created 7.4 pounds of carbon dioxide equivalent greenhouse gases, while half a pound of chicken only produces point .55 pounds for a difference of 13 to 1. This is mainly because cattle produce huge amounts of Methane which is 23 times stronger than Carbon Dioxide as a greenhouse gas. Argentina, which is a cow intensive country may be getting 30% of its greenhouse gas emissions from cattle.
Chickens are apparently amazing protein factories. A broiler chicken can be produced in as little as six weeks while beef cattle take from 1 1/2 to 2 years to raise. I therefore concluded that chicken should be the meat of choice for an environmentally responsible carnivore and beef should be eaten only on special occasions. She listened to what I said and replied, "What about cheese?" I was dismayed by this, since I don't eat beef that often anymore, but I use a lot of cheese, so I decided to find out the greenhouse gas footprint of cheese.
I didn't find any link giving me the number for cheese. It is only recently that scientists have started trying to account for Methane output from food production.
First I found a number for how much milk a cow produces in a year. The number I found was 8,992 kilos of milk. It apparently takes 12 kilos of milk to produce 1 kilo of cheese which works out to 749 kilos of cheese per cow per year. The Swedish study lists the cheese on a Big Mac at 14.5 grams per slice. That works out to 69 slices per kilo or 51,681 slices per cow per year. If you get 440 pounds of meat at 14.8 pounds of Carbon Dioxide per pound, then one beef cow is equal to 6,512 pounds of carbon.
I wasn't sure how the GHG footprint of dairy cows compares to beef cattle, but the EPA seems to think that dairy cows produce 4 tons of Carbon Dioxide equivalent greenhouse gases per year, since their regulations kick in at 100 tons per year and they want a license for 25 dairy cows. They estimate 2 tons per beef cattle which comes out to 1.6 years to raise a cow for beef, which is about right.
If you use, 1652 pounds of cheese per year per cow, that that works out to 4.8 pounds of Carbon Dioxide equivalent per pound of cheese as compared to 14.8 per pounds of Carbon Dioxide equivalent per pound of beef or about 1/3 as much GHG emissions. This is worse than pork which is 3.8 pounds. Of course, very few people eat cheese by the pound. At 14.5 grams per slice, that would work out .15 pounds of GHG compared to 3.7 pounds for the 4 oz patty. The fat free singles I buy weigh 19 grams and work out to .2 pounds of GHG.
It looks like putting a slice of cheese on your sandwich is not a major environmental sin.
References:
How Meat Contributes to Global Warming:
Meeting the demand: An estimation of potential future greenhouse gas emissions from meat production
Energy Use in the Food Sector:A data survey
Cow Backpacks Trap Methane Gas
How much milk do cows produce?
EPA Proposes "Cow Tax"
http://www.cattlenetwork.com/EPA-Proposes--Cow-Tax/2008-11-18/article_FeedByproducts.aspx?oid=556872
How many hamburgers can you get out of one cow?
