Which milk is best for Earth? Science explains why your fave is problematic

Whether it’s frothed covering a latte or dousing a bowl of Cheerios, milk is a staple part of many diets. But the dairy milk of your grandparents’ kitchen has a dark, not so well kept secret: it’s an environmental nightmare.

Between the environmental costs of tending farmland and feeding herds of dairy cows, dairy milk has been blacklisted by many environmentalists. But just how much better are the plant-based options that have risen up from dairy milk’s ashes?

Curtin University’s Dora Marinova, a professor of sustainability, and Diana Bogueva, a post-doctoral researcher, help Inverse explore this question and set the record straight. Ultimately the answer is best for the most indecisive among us.

“There is a risk associated with pointing at one particular plant-based milk as being the best,” they explain. “This will create a lot of interest by the consumer and can lead towards over-exploitation of that particular plant.”

Is dairy milk bad for the environment?

According to a 2018 study published in Science by University of Oxford researchers, the environmental impact of dairy milk production is three times higher than that of other plant-based alternatives.

“Any plant-based milk is better than animal milk.”

To put this into perspective, a year of drinking one glass of dairy milk (approximately 200 milliliters) a day for three to five days creates the same amount of greenhouse gas emissions as driving a gas-powered car over 300 miles — about 131 kilograms.

Marinova and Bogueva explain to Inverse in an email that this stems in part from the environmental costs of maintaining a dairy farm itself.

“Cows and sheep are ruminant animals and they emit a lot of methane,” they explain. “There are also the added inefficiencies of feeding grains to the animal first to produce milk for human consumption while we can make milk directly from the plants.”

And pouring dairy milk into your coffee or sitting down to enjoy a glass with dinner isn’t necessarily where these environmental impacts stop, say Marinova and Bogueva. They also show up in our processed dairy products, like yogurt and cheese.

“Milk is used not only for ice cream but also for yogurt and a large variety of cheeses,” they explain. “In the West, we are drinking less milk but eating more cheese and yogurt.”

While plant-based milk has gained popularity the transition to plant-based yogurt and cheese has been slower, they say.

“Ultimately individual food preferences determine what larger food companies offer to the market,” say Marinova and Bogueva.

Is plant-based milk better for the environment?

In the 1990s and early 2000s, soy milk was about the only plant-based milk you could get your hands on. Today it’s a very different story today: In addition to soy milk, large grocery store chains now also sell nut-based milk (like cashew, macadamia, almond, or hazelnut) as well as coconut, oat, hemp, or rice-based milk.

“My advice to consumers is to diversify their choices.”

But that doesn't necessarily mean that all plant-based milk is created equal.

Marinova and Bogueva say that there are several key variables to look for when determining the impact of plant-based milk:

• CO2
• Methane emissions (like might be released from natural fertilizer like manure)
• Nitrous oxide emissions (associated with synthetic fertilizers)
• Land and water use for cultivation, including if the farming involves native habitat destruction

They add that time can also be a factor in how these variables are measured and when their ultimate effect is felt.

“The time horizon for measuring the impact can also vary — between 20 and 100 years,” explain Marinova and Bogueva.

“For example, methane is 84 times more powerful than CO2 over a 20-year time horizon compared to 26 times on a 100-year time horizon as methane breaks down in the atmosphere within 20-25 years.”

What plant-based milk is best for the environment?

Any mass-produced food product will have its downsides, say Marinova and Bogueva, but a rule of thumb they suggest when picking your next milk is to diversify instead of go all-in on one in particular.

“My advice to consumers is to diversify their choices and drink soy, almond, oat, hazelnut or hemp milk or whatever plant-based milk is available locally,” they say.

With that in mind, there’s some plant-based milk that you may want to use less frequently in your rotation, including:

• Almond milk (which guzzle more water than any other plant-based milk and can be bad for bees)
• Coconut milk (which has been tied to poor labor practices)

“[But] any plant-based milk is better than animal milk,” say Marinova and Bogueva.

Is lab-grown milk bad for the environment?

Plant-based milk is the clear champ over traditional dairy milk when it comes to environmental impact, but what about dairy milk 2.0, aka lab-grown dairy milk?

Companies like Perfect Day are using microflora to create tasty milk proteins, like whey and casein, from scratch without any input from a dairy cow.

“This will be definitely better from an environmental point of view, particularly if the energy required to make the synthetic casein and whey comes from renewable sources,” say Marinova and Bogueva.

“Obviously, such products will not require as much land and water. We may be able to make them with an even smaller environmental footprint.”

As Perfect Day has already demonstrated with its ice cream products, which it spoke to Inverse about last year, Marinova and Bogueva suggest that these lab-grown alternatives could help finally make a dent in replacing dairy-based products, such as cheese or yogurt.

“There is a lot of innovation happening in this space and the main reason is that the world cannot continue with its current ways of food production.”

CHECK, PLEASE is an Inverse series that uses biology, chemistry, and physics to debunk the biggest food myths and assumptions.