How green is your milk? We compare the environmental cost of dairy and plant-based options

Oat cap, skinny flat white, almond chai, soy matcha. Everyone has a different milk preference: cow, skim, lactose-free, oat, almond, soy, goat or camel.

Milk choices may be due to environmental reasons, dietary concerns or just taste preferences.

Australians cut back from drinking 100 litres of cow’s milk a year in 2015 to just 85 by 2025, according to Dairy Australia.

It’s estimated that 96% of Australians consume animal milk, yet 42% buy plant-based milk – some households have multiple milk types.

The decrease in dairy milk sales reflects a cultural shift towards plant-based options, with almond milk and soy milk consumption up since 2018-19.

But are plant-based milks as virtuous for the environment as they appear, and is dairy unfairly demonised?

Dr Michalis Hadjikakou, who researches sustainable food systems at Deakin University, says there’s a lot of nuance when it comes to making sustainable food choices. “You need to consider what the purpose of drinking the milk is,” Hadjikakou says. “If I was looking for a milk for my children, I probably would make a different decision than if I was looking for a milk for my coffee.”

Aside from nutritional considerations, there are many factors to assess for environmental impacts. Fertiliser use, water consumption, packaging and processing as well as emissions all come into play.

So, does dairy, oat, soy or almond come out on top?

What’s better for the environment, plant-based or cow milk?

Emissions are the first thing that comes to mind when considering the environmental impacts of milk. “All of the plant-based options are pretty low on emissions,” Hadjikakou says. “Soy, oat and almond all have lower emissions [than dairy].”

Cows produce methane during their digestive processes, which is then burped out into the atmosphere. In Australia, it’s estimated that 11% of our total greenhouse gas emissions comes from ruminant livestock digestion.

According to the World Resources Institute, the average emissions per cup of milk is 330g for dairy, 122g for soy, 102g for oat and 98g for almond.

Fraser Taylor is the managing director of FoodSwitch at the George Institute for Global Health, creator of the ecoSwitch app. The app collates data about the environmental impacts of different foods so consumers can compare them.

“We’ve been working on a really big update to our data,” Taylor says. Instead of a five-star planetary health rating, FoodSwitch has opted for a 0-100 scale – with 100 as the best possible score – and expanded the scope of greenhouse gas emissions to include data from “farm to fork”.

For dairy milk, Taylor says, “the rating is now around 85 out of 100 … and soy milk as a comparison is 96.” Taylor notes FoodSwitch doesn’t have ratings for oat and almond because of a lack of data but says soy is fairly representative of other plant-based milks.

“Plant-based milks still definitely do have a better environmental footprint than dairy milks, particularly on greenhouse gas emissions,” Taylor says.

What is the least environmentally friendly milk?

“Oat hands down is the best option for water,” Hadjikakou says, although water use can vary depending on how and where crops are grown. “Oats are a dryland crop … It’s grown in those zones where you’re essentially relying on rainfall with very little supplementary irrigation.”

For dairy and soy, water use depends on the farm and location within Australia. “Some dairy might completely rely on natural grass that doesn’t use much water, but some might rely on irrigation,” he says.

The impact of water consumption depends on water scarcity. If you use 100 litres of water to produce soy milk in an area where water is plentiful, this would be less of a concern than in a region where water is more scarce.

But for almonds, it’s a different story. “Almonds would have the highest water footprint,” Hadjikakou says. “Almonds like a Mediterranean climate. They actually like being rather hot and warm with not much rainfall so you can regulate irrigation.”

Taylor agrees, saying almond milk’s water use “brings it down a fair bit” in its environmental rating.

In terms of water usage, oat milk comes out on top, with dairy and soy falling next in line (depending on the farm and location) and almond ranking last.

What about processing and packaging?

For all four main milk types, processing is required. “In the case of cow’s milk, you basically get the milk from the cow and then pasteurise it,” Hadjikakou says. “A lot of these other milks involve soaking, heating, adding things like calcium and fortification. There’s definitely some additional steps involved.”

Some research suggests that the processing and packaging of plant-based milks can contribute up to 79% of their environmental impact compared with 4% for cow’s milk.

But Taylor says even when considering the “downstream phases” including processing and transportation, plant-based milks contribute about 1kg of CO₂ per litre of milk produced, and dairy or animal-based milks produce 3kg of CO₂ per litre of milk.

Hadjikakou says another main consideration for environmental impacts is fertiliser. Fertiliser is essential to replenish nutrients in the soil, increase plant yield and ensure food security.

“Fertiliser is where something like soy beans would probably be better for the reason that it is a legume,” he says. “It has fixed nitrogen – it actually helps the soil.”

For oats and dairy, Hadjikakou says it depends on where you are. In Victoria farmers used about 198kg of fertiliser products per milking hectare in 2024-25, down from almost 250 in 2020-21.

Generally, oat crops use 40 to 80kg of nitrogen per hectare, while dairy uses 143kg.

“Almonds are a little bit hungrier in that regard,” Hadjikakou says. But he reiterates that for oat, dairy and almond, it depends on the farm practices and location.

Which is the creme de la creme?

“There’s no clear winner,” Hadjikakou says. “They each do pretty well at different things.”

For reducing milk-related emissions, he suggests “having a little bit of each”.

“Perhaps on your latte you could have almond [milk], for your cereal you could have cow’s milk.

“In that way, you’d still reduce your emissions.”