Over at the BBC, I ran across something really silly: a climate change food calculator.
According to the calculator if I drink a glass of milk a day (defined as 200 ml/day), it says that it is the equivalent of driving a car 941 km and that it uses an astounding 45,733 liters of water and 652 meters square of land.
What if I drink 2 glasses of milk a day? According to the calculator that is the same as driving a car 1883 km and uses 91,466 liters of water and 1303 square meters of land. Basically twice as much of everything.
It sounds tremendously wasteful.
On second thought, however, can that possibly be right?
At 200 ml of milk per day over 365 days in a year, someone who drinks a glass of milk a day drinks 73 liters of milk a year, which means that it takes 626.5 liters of water to produce 1 liter of milk. That sounds terribly inefficient. According to the calculator, that is the same as taking almost 4 showers per day.
Something seems funny with that number. Does a cow really take 626.5 gallons of water to produce a gallon of milk? The average dairy cow produces 8 gallons of milk per day. According to the BBC, each cow must drink 5,012 gallons of water a day. Can that possibly be right? According to the agriculturalists at the University of Nebraska, the average cow drinks between 3 to 30 gallons of water per day. Assuming the worst case scenario, the BBC has cows drinking 167 times as much as the University of Nebraska.
Another problem is the scaling. The average dairy cow produces far more milk each day than I can drink, even if I am on a milk only diet. So how many cows does it take to supply my one glass of milk a day? One. How many cows does it take to supply my milk drinking if I drink two glasses a day? One. How many cows are required to provide my milk if I drink one glass a month? One. That cow also needs to eat and drink the same amount whether I drink one glass a month or two glasses a day. The results (at my level of consumption) are the same regardless of my level of consumption. Not only is the idea that it takes 45,733 liters of water to produce a glass of milk a day ridiculous, but the notion that 91,466 liters of water to drink two glasses a day is even more absurd. And the only way to get the cow to stop consuming water is to kill it. What does the BBC have against cows?
That seems like an outrageous question, but in fact it is not.
Consider what happens if, instead of plugging in milk into the calculator, we plug in the alleged beverage of choice for Britons: tea. According to the BBC calculator, a cup of tea a day for a year (about the same amount as milk) in the equivalent of driving a care 63 miles. Doesn't that sound oh so much more virtuous. But how much water will it use? The BBC calculator suppresses that information. They will tell you that having a pint of beer a day (double the amount of tea or milk) will use 3,535 liters of water per year. A really thirsty cow would actually only drink 547.5 liters of water per year to produce that much milk. So milk would seem to be a more efficient use of water than beer, but since they are not accurate in describing milk why should we assume that they are more accurate in describing beer?
Which brings us back to the question, what does the BBC have against cows? On their page they said that they put together their calculator because they claim that "the West's high consumption of meat and dairy is fuelling global warming." So is their solution that we should just kill all the cows and let the carcasses rot without eating the meat? Somehow that does not strike me as being good for the environment.
