Lindsey Balbierz

Lovers of butter, champions of cheese: Please, slow down. In a recent study documenting the carbon footprint of the American diet, NRDC policy experts reported that while beef consumption fell significantly between 2005 and 2014, our appetite for many dairy products grew. And unfortunately, aside from whatever you may have picked up at the butcher counter, that hunk of gouda is one of the most greenhouse gas–intensive foods you can add to your shopping cart.

After all, meat and dairy have a common source. “It takes a lot of energy input to raise cows,” says Sujatha Jahagirdar Bergen, a policy specialist with NRDC’s Food and Agriculture program. For starters, “you need to grow the feed [mostly grain], which takes lots of pesticides and fertilizer”—a significant source of global warming pollution. Then there are the smellier factors. “After the cows eat that feed, they release methane through their digestive systems, and then their manure also produces lots of greenhouse gases,” Bergen says. NRDC has documented high levels of methane emissions from the “lagoons” where factory farms dispose of animal waste. Another particularly nasty by-product of cow dung is nitrous oxide, a climate-warming pollutant 298 times more powerful than carbon dioxide.

The simplest course of action, says Bergen, is to follow the advice of Michael Pollan: Eat more plants and fewer animal products. And when you do make your way through the dairy aisle, keep these tips in mind.

Consider plant-based milks . . .

Soy, rice, oat, hemp, almond, coconut—there are certainly a lot of nondairy options to add to your coffee. But from an environmental perspective, consensus is hard to come by regarding how they stack up against each other and how they compare with cow’s milk. Soy seems to be the best understood. Researchers who compared the units of fossil-fuel energy required to produce milk and soybeans found that it takes 14 kilo-calories (kcal) of fossil fuels to produce a single kcal of dairy milk, whereas just 1 kcal of fossil fuels can produce 3.2 kcal of soybeans. That measurement takes into account the fertilizers, pesticides, and other industrial inputs used in agriculture.

. . . But note the trade-offs.

The carbon footprint is only one aspect of a given food’s sustainability; it’s also important to consider the source of the product (such as whether the soy is sustainably farmed) and the other resources, such as water, needed to produce your nondairy milk. Nondairy beverages also require additional processing—after all, those 3.2 kcal of beans have a long way to go before they are transformed into your vanilla soy milk.

Some studies have questioned whether nondairy milks are indeed healthier alternatives to animal milks. Many of these vegan options contain sugar, which comes with its own set of health problems. A group of Swedish researchers analyzed the nutritional value of a variety of beverages in relation to their climate impacts, including milk, soy, and oat drinks, and found that milk had the highest nutrient density in relation to greenhouse gas (GHG) emissions. “It’s becoming increasingly important to examine food’s environmental impact per unit of nutritional value, rather than simply per pound or kilogram,” says livestock sustainability consultant Jude Capper, who notes the healthy combination of fat, protein, and minerals found in cow’s milk.

If you’re sticking with dairy, read the labels.

You can cut down on dairy without abandoning cow’s milk entirely. Look for brands produced locally, when possible, to help offset transportation emissions. Also choose milks certified organic, which come from farms that are largely free of synthetic pesticides and fertilizers. The caloric content of your milk also impacts its carbon footprint. Research by the Food and Agriculture Organization of the United Nations has shown that low-fat milk options are associated with lower emissions, with skim milk powder resulting in lower GHGs per kilogram than whole milk powder―as much as 9 percent less. The carbon savings come from the other products, like butter or heavy cream, made from the skimmed fat. “As milk fat has a high value, semi-skimmed milk will be cited as having a lower carbon footprint than full-fat milk,” says Capper, “simply because some of the resource use and GHG emissions is allocated to the cream coproduct.”

Go lighter on the butter.

We hate to break it to you, butter lovers, but your favorite spread is a detriment to more than just your waistline. Butter ranks third on NRDC’s chart of 10 common climate-damaging foods. If you’re wondering why, consider this: To get a pound of butter, you need 21 pounds of milk.

Say (young, low-fat) cheese!

Can we put this delicately? Not really. The environmental impact of cheese is pretty heavy. Among the top foods contributing to emissions increases from the American diet between 2005 and 2014, cheese is listed three times. It’s broken out into American, the country’s most commonly consumed (and most processed) cheese; mozzarella; and “other Italian cheeses.”

Though the NRDC study ranked these cheese categories as contributing the same levels of GHGs (9.78 kg CO₂ eq/kg), different factors are at play for each. American’s inclusion on the list came from the sheer volume of yellow slices we consume, Bergen points out. The impact of those assorted Italian cheeses comes in part from the shipping requirements—the Environmental Working Group estimates that airfreighting cheese increases its overall emissions by about 50 percent—and partly from the long-term refrigeration required for aging. A cheese’s density also makes a difference. So even though mozzarella is a top seller—because Americans each so much pizza, Bergen says—its lightness helps its relative carbon footprint. In a side-by-side analysis of cheddar (63 percent milk solids) versus mozzarella (51 percent milk solids), the mozzarella proved to have a lower environmental impact.

Don’t forget the first ingredient in yogurt. (It’s milk.)

Another dairy product that has become a fixture of the American diet, yogurt also appeared on NRDC’s top 10 list of foods contributing more GHGs. It’s important to note that producing Greek and other strained yogurts, which now dominate dairy cases, takes four times more milk than regular yogurt, according to The Science of Cheese. And its resource intensity is not its only environmental drawback. The yogurt industry has also had to contend with an increasing output of whey pollution. The acidic whey strained out of Greek-style yogurts is treated as a waste product, and its decomposition can be toxic to the environment. In 2008 an accidental spill of the watery substance from an Ohio dairy factory into a local creek killed more than 5,000 fish.

Dairy producers are trying to compensate with some new—and some old—whey recycling techniques. “Whey has been used in animal feeds for years,” Capper says, “but now there’s an increasing market for whey proteins as food supplements for athletes and health-conscious consumers, especially given how digestible milk proteins are compared with plant proteins.” Some niche producers are starting to notice the value of these by-products. Just look at Brooklyn, the birthplace of so many American food trends. One of its latest innovations comes from a manufacturer called the White Moustache, now cornering the market on whey-based probiotic tonics. It’s trendy, and it helps offset emissions. We’ll drink to that.