Megan Hall: Welcome to Possibly, where we take on huge problems like the future of our planet and break them down into small questions with unexpected answers. I’m Megan Hall.
We’ve talked a lot about the carbon pollution that comes along with eating beef, but what about eating dairy? And how do they compare?
We had Samantha Zhang and Nat Hardy from our Possibly Team look into this.
Samantha Zhang: Hi, Megan!
Nat Hardy: Hello!
Megan Hall: So, what creates more carbon emissions? Beef or dairy?
Nat Hardy: Let’s start with the obvious overlap between the two… cows. We know that cows use a lot of resources.
Samantha Zhang: They need land to graze, and lots of feed.
Megan Hall: But what does feed have to do with carbon pollution?
Nat Hardy: Well, it takes a lot of energy to make feed-- from fertilizers to grow it, tractors to plant and harvest it, and trucks to deliver it.
Samantha Zhang: Not only that, because of the way cows’ stomachs process food, they belch out methane —a greenhouse gas that’s much more potent at warming the planet than carbon dioxide.
Nat Hardy: And of course, we can’t forget that their manure also creates methane.
Samantha Zhang: But one major difference between beef cows and dairy cows is how long they live. Dairy cows stay on the farm for about 5 years, while beef cows get slaughtered after about a year and a half.
Megan Hall: What kind of difference does that make when it comes to pollution?
Nat Hardy: For starters, cows that live longer have more to offer. It takes about two years for a cow to start making milk.
Samantha Zhang: So really, during those early years you have to feed them, they burp out methane, but they aren’t making anything.
Nat Hardy: When a dairy cow sticks around for five years or more, you’re getting at least three years of milk in exchange for all of the things they do that create carbon pollution.
Megan Hall: So, letting dairy cows get a bit older is more efficient?
Samantha Zhang: Exactly. But there’s more. With dairy cows, you’re kind of getting a 2 for 1.
Nat Hardy: To find out more, we talked to Dr. Matthew Hayek, an Associate Professor in the Department of Environmental Studies at NYU.
Matthew Hayek: The dairy cow is producing multiple products for human consumption. First of all, a lot of milk. And second, she is probably going to be slaughtered and rendered into beef that is used in hamburger meat. Then also, she will have offspring.
Nat Hardy: Compare that to a beef cow that is used for only one thing— beef— and suddenly dairy cows are looking way more efficient.
Megan Hall: So dairy cows create less emissions overall, because those emissions are being divided up in between amounts of milk and cheese and beef.
Samantha Zhang: Exactly! So if we take a look at the numbers, the emissions for around two pounds of beef from a cow that’s JUST used for beef is about 60 kilograms of CO2.
Nat Hardy: But, beef from a dairy cow comes in at about 20 kilograms of CO2. So only a third as much.
Megan Hall: So, less emissions, for the same thing! What about milk?
Samantha Zhang: Well, 2 pounds of milk produces way less emissions---about 20 times less than beef from a dairy cow.
Megan Hall: Where does cheese rank in terms of greenhouse gases?
Nat Hardy: Well the surprising thing is, cheese creates a ton of emissions per pound. It’s up there, with the emissions from beef that came from a dairy cow, though it depends on the type of cheese.
Megan Hall: Why is cheese so similar to beef?
Nat Hardy: Well, consider how much milk goes into a kilogram of cheese.
Samantha Zhang: That’s the thing to keep in mind about these metrics: they can really change depending on the measurement. Since…
Matthew Hayek: Different types of food have different quantities of water, protein, fat, calories in them, depending on which you choose to report by, you’re going to have very different answers in that comparison.
Nat Hardy: So, say we weren’t looking at the emissions by weight, but instead we were looking at it based on the amount of protein.
Samantha Zhang: Then you’d get more emissions for milk, once you took out all the water weight. Going back to cheese, it…
Matthew Hayek: Might look like very high emissions by comparison, because you’ve removed most of the water in order to perform that fermentation.
Nat Hardy: The numbers might change based on how you measure it, and beef is definitely worse than dairy, but in the end food that comes from a cow is always going to make a lot of emissions.
Megan Hall: Got it! Thanks, Samantha and Nat!
That’s it for today. You can find more information, or ask a question about the ways your choices affect our planet, at ask possibly dot org. You can also subscribe to Possibly wherever you get your podcasts or follow us on social media at “ask possibly”
Possibly is a co-production of Brown University’s Institute for Environment and Society, Ocean State Media, and WBRU.
