How green is your glass of milk, and should we move away from dairy?

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The environmental case against cows' milk seems open and shut. A 2018 study by the University of Oxford found that producing one glass generated three times more greenhouse gas emissions than plant-based alternatives. It also required nine times more land.

The conclusion is obvious, says Sadhbh O’Neill, policy coordinator with Stop Climate Chaos, which campaigns to ensure Ireland does its fair share to tackle the causes and consequences of climate change.

“We need to move away from dairy,” she says. “All scientific assessments of the most sustainable diets show plant-based diets are best for the environment when you calculate all the potential environmental impacts. This means adding up greenhouse gas emissions from livestock, feed, and land use and comparing it with a diet that uses less land, water, and inputs.” 

We don’t even need dairy, according to O’Neill. “Cow’s milk is not essential to the human diet and people can easily adapt to substitutes that are readily available in supermarkets,” she says.

Sustainable eating 

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Before you swap your milk bottles for cartons of oat milk, there is more to consider. All plant-based milks may generate less greenhouse gas emissions than cow’s milk, but some are better for the environment than others.

“There are numerous things that need to be considered when we talk about eating in a sustainable way,” says Dr Lana Repar, a lecturer in the Department of Food Business and Development at UCC. “We need to look at the whole picture. If we increase the average production and intake of plant-based foods and decrease the production of animal-based foods, how will this shift impact the environment, producers, and consumers?"

 There are so many aspects that add to the environmental impact of certain choices, says Repar. “We need to think about how intensive crop production impacts soil and water quality and biodiversity. Airfreight adds to environmental impact too.” 

These considerations need to be balanced with our nutritional needs. “Plant-based milks don’t come close to cow’s milk in terms of nutrition,” says Sarah Keogh, a dietitian at the Eat Well Clinic in Dublin. “People shouldn’t fool themselves that these are healthier options.” 

Environmental cost

So how do plant-based milks compare to dairy and each other?

Almond milk costs approximately €2.30 per litre compared with €1.30 for cow’s milk. Its greenhouse gas emissions may be lower, but it has environmental drawbacks.

According to the US Department of Agriculture, about 80% of the world’s almonds are grown in California, where water is a precious resource. Almonds guzzle that water, with a 2019 study by California State University showing that it takes 12 litres to produce a single nut.

Pollinating almonds is problematic too. Nearly 70% of commercial bees in the US are drafted in to help with this every spring but farming practices can be harmful to pollinating bees. Pesticide use is thought to be why a record one third of these bees died in the winter of 2018-2019.

Furthermore, almonds are pulverised and mixed with water to make milk, which waters down their nutrients.

“100g of cow’s milk contains up to 3.5g of protein, 120mg of calcium, and 31mg of iodine,” says Keogh. Almond milk’s score is much lower. “100g contains 0.5g of protein, 0.1g of iodine, and the calcium content is minimal unless it’s fortified,” she adds.  

Greenhouse gas emissions

What about rice milk with its subtle sweet flavour? It sells for approximately €2.30 per litre and is made from an inexpensive crop that is widely available. Does that make it a good choice?

An Oxford study found that rice milk produced more greenhouse gas emissions than other plant milks due to bacteria that breed in paddy fields, pumping methane into the atmosphere, and its high dependency on fertiliser, which pollutes waterways.

Rice milk also has little to recommend it nutritionally. “100g contains 0.3g of protein and little to no vitamins or minerals,” says Keogh.

Coconut milk, retailing at about €2.40 per litre, is seen as a healthy option but its production methods can be far from healthy. The Philippines is one of the world’s main producers of coconuts. A 2018 report published by the UN found that 60% of the country’s coconut farmers live in poverty, pushing them to expand their farms into the rainforest.

Does the nutritional content of coconut milk warrant its environmental cost? “100g only contains 0.2g of protein, very little calcium, and 0.04g of iodine,” says Keogh.

Good protein level 

Soy milk, the original plant-based milk, retails at around €2 per litre. With 3.3g of protein per 100g of milk, it’s the only one that compares to dairy from a dietary point of view.

Environmentally, it’s more complicated. The production of soya milk uses less than a tenth of the water almond milk does. And, because it’s a legume, it fixes nitrogen in the soil, which reduces its need for fertiliser.

But it requires a lot of land. So much so that swathes of the Amazon are being cut down to make way for soy plantations. Those soybeans are then treated with pesticides, polluting the ecosystem.

For a guilt-free soy latté, choose organic and check the source of the soybeans, avoiding any milk made from beans grown in the rainforest region.

Oat milk is a newcomer to the market, with a cost of approximately €2.40 per litre.

A plus is that according to a 2010 UNESCO report, oats use the least water of all plants that are turned into milk. A minus is that most oats are sprayed with pesticide before harvest.

Its nutritional content is minimal too. “It only contains 1g of protein per 100g and has no calcium,” says Keogh.

However, O’Neill believes that if it’s grown organically here in Ireland, it may be the best option for us. “Supporting local food production has the least environmental impact and, in Ireland, that means organic Irish oat milk,” she says.

The choice is up to you, the consumer.