Vegetarians, does this influence your decision to consume milk?

For those of you who avoid meat, but still consume dairy; are you aware of the high levels of greenhouse gasses (GHGs) emitted in dairy production?

A new study found that a single US dairy with around 11000 cows emitted 33,162 pounds of methane and 410 pounds of nitrous oxide every day. CO2 emissions from the cattle were estimated at around 27kg per cow per day, but they weren't certain about this because there were also CO2 emissions from nearby machinery which influenced the total. So I have omitted direct CO2 from the following calculations, focussing only on nitrous oxide and methane.

To compare emissions with carbon dioxide, we use an index called the Global Warming Potential (GWP) which incorporates the specific forcing of a particular GHG. Methane (CH4) has a GWP of 22, meaning that every molecule of methane generates the same amount of warming as 22 molecules of CO2; while nitrous oxide (N2O) has a GWP of 310 over the same period. I crunched the numbers for you:

N2O = 121064 CO2 eq.

CH4 = 694932 CO2 eq.

For a total of 815996 pounds of CO2 emitted EVERY DAY.

The researchers state that this means for every pound of milk produced, 0.04 pounds of methane, and around 0.0006 pounds N2O are produced. That equates to a CO2 equivalent of:

1.11 kilograms CO2 per litre of milk

= 2.44 pounds per litre

= 0.6344 pounds per gallon(US)

= 0.5368 pounds per gallon(UK)

Interestingly, they state that previous research has shown emissions to be more than twice as much in other dairy systems. Note that this is only the production of the milk before it is actually milked and does not include the emissions from the energy required to milk the cows and pasteurise the milk, nor the transport emissions in distribution, nor the CO2 emitted from respiration as previously stated. So by the time it gets to your fridge the total amount is much higher, depending on how far it travels.

Since dairy products are something we can all easily live without, is this something you would consider forgoing in order to reduce your impact on the planet? If not, why not? Would you prefer to continue consuming milk but to offset these emissions and if so, how will you offset them?




Leytem et al. (2011). Emissions of Ammonia, Methane, Carbon Dioxide, and Nitrous Oxide from Dairy Cattle Housing and Manure Management Systems. Journal of Environmental Quality:

Discussion by USDA ag research (see section "Calculating the Impact of Cows"):

GWP index:

Density of milk (used to work out ratio of CO2 per litre/gallon):

Update 2:

@sulu:these are the important numbers, the rest is just background on how I worked them out:

1.11 kilograms CO2 per litre of milk

= 2.44 pounds per litre

= 0.6344 pounds per gallon(US)

= 0.5368 pounds per gallon(UK)

reducing the number of cows reduces methane emissions, so eating cows doesn't help as it will encourage their production

Update 3:

@Dowling- ridiculous. How can methane be collected from ruminants as it comes out of their mouths to be used for fuel? Most of the emissions are not from their waste, it is produced by regurgitating their food to chew the cud. No responsible person puts vegetable scraps in with the garbage, we compost it instead. And human waste can be used for fertiliser. So don't feel sorry for us...

7 Answers

  • Anonymous
    8 years ago
    Best Answer

    Gawd! Those figures are pretty horrendous. That really puts in into perspective for me. I don't have cows' milk/products (but do have a bit of goat cheese now and then - how does that rate?) but it is used in our home by others. For a while now I've been trying to discourage it and will renew my efforts. I shudder to think of all the litres of milk consumed in the world on an hourly basis, let alone annually.

    Just in case Dowlinggram returns to read other posts - methane emitted by treatment of human waste and decomposing vegetable matter is easier to harness than that emitted by cows (unless you want the cows to have an even more miserable life closed away indoors with masks attached to their heads - the problem is burps, not farts). Humans are always going to sh*t, whereas having vast numbers of cows is optional. Another point of concern is your belief that dairy = calcium. This is a myth put out by the wealthy dairy industries. There is far more osteoporosis in the milk-drinking western world than anywhere where milk is not a staple food.

  • Anonymous
    8 years ago

    A counter argument that some people might throw at you in regards to this post is:

    "Well, if we just let all of the cows free they would overpopulate and cause even more methane to be released."

    You can then correct them with the fact that any animals that is not farmed, due to our increasing destruction of the world, suffers population decreases annually. Think of lions and tigers and random other animals. They aren't farmed, and I don't see many of them walking around...

    Freeing the cows would actually REDUCE their population, and therefore reduce greenhouse emissions.

  • Anonymous
    8 years ago

    Absolutely. The reason I don't eat milk or milk products anymore is because I found it pointless to remove beef from my diet for environmental reasons and yet still buy into the dairy industry which produces just as much greenhouse gases, not to mention that every glass of milk supports the veal industry and dairy cows end up as meat anyway. That is why I only eat eggs from my 9 beautiful chickens and don't buy milk anymore.

    Source(s): Vegetarian
  • 8 years ago

    Interesting but I have something more interesting. Just take a look at the table below put out by the US government. You will see that the methane from cows almost equals the methane put out by treating human sewage and the biggest emitter of methane is garbage dumps where your vegetable scraps are decomposing.

    Further more methane can and is in places for fuel. More and more people are realizing that that methane gas is a valuable resource. There is one farm that I know of on the east coast of Canada that captures this gas and uses it to power it's operation. Some cities are capturing it from their landfills.

    Instead of being so gung ho vegetarian look around and see how problems are being solved. I feel sorry for all you people who are not eating dairy. You are doing your bones a disservice. Dairy is the biggest supplier of calcium in our diets. I urge you all to get bone density tests and at least take calcium and vitamin D supplements. Osteoporosis is a painful debilitating disease. I know in me it was caused by a life long lack of calcium and vitamin D, both of which we need for our bones

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  • anon
    Lv 5
    8 years ago


    However, I can live without milk, and if I were buying the groceries we wouldn't have milk, cheese, or eggs in the house. But, because it is in the house, if I run out of soy/almond/rice milk I will use dairy. It's there so why waste it.

    If you're so worried about methane gasses, you may as well condone people eating cows.

  • J
    Lv 6
    8 years ago

    I think humans will destroy this planet's ecosystem no matter what.

    The biggest reason for me to not eat dairy would be welfare of dairy cows and calves, however I have a real hard time giving up cheese.

  • Suzy Q
    Lv 7
    8 years ago

    No. I am already aware of this. Not these specific numbers, but ballpark for the Dutch situation.

    I never claim to be perfect, I just try to do my bit in my way by not eating meat.

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