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Plant based milks versus dairy milk

More and more people in the UK are switching to plant-based milks as an alternative to dairy.

How much better are they for the climate, what about nutrition, and which is the best plant milk for the environment?  

Also see our guide to ethical milk brands, and guide to vegan & plant milks.  

Does dairy or plant milk have a higher carbon impact?

For the average person in the EU, around a quarter of all emissions from food comes from dairy. Switching to a plant-based milk like oat or soya can significantly reduce your climate impact. 

For each litre of dairy milk produced, it has almost three times the carbon footprint of the next highest emitter, rice milk.

Infographic showing greenhouse gas emissions and land use for different milks. Figures in table on page.

Why are emissions from dairy so high?

There are two main reasons why animal products like dairy are bad for the climate: methane and land use.

Cows burp large amounts of methane while digesting grass. Methane is a very powerful greenhouse gas. If looked at over a short timespan, 1 tonne of methane can warm the planet many times more than the same amount of carbon dioxide. In fact, if considered over the first 20 years from when it was emitted, it has 84 times the warming potential of CO2.

Cows also require large amounts of land, for living, grazing and feed, as discussed below. Unfortunately, land comes with a carbon footprint attached.

Every metre of land we use for cattle grazing or feed production is a metre where trees or other natural ecosystems cannot grow. These ecosystems are crucial carbon sinks – ways of capturing carbon back into the natural world and therefore addressing global heating.

Of course, growing crops also requires space, and can emit greenhouse gases. But it is much more efficient to grow crops for ourselves than to grow them to feed to a cow and then to live off animal products.

If a cow eats some soybeans, they won’t store all the energy to go into milk or a burger: they’ll use some of it up by, for example, breathing or walking around. If we ate the same amount of soya ourselves, we’d have received much more energy in proportion to the land required to grow it, or the emissions released.

We look at the carbon impacts of food choices in more detail in a separate article.

Soya and deforestation

Many people have rightly pointed out that in the Amazon, soya farming is driving deforestation. In just one state of Brazil, Mato Grosso, over 400 square miles have been felled to expand soya farms in the ten years up to 2019.

But the demand for more and more soya is not coming from vegan consumers: it’s driven by the livestock industry. More than three-quarter of soya globally is used as animal feed, versus just 7% consumed directly by humans.

If you are concerned about where your soya beans are grown for your soya milk, look on the carton to see what it says, or contact the brand who make it to ask where the soya beans are from.

Does dairy or plant milk use more water?

Over the last few years, many consumers have been concerned about the significant quantities of water required to grow almonds. Yet, producing a litre of dairy milk requires about 70% more water than a litre of almond milk.

Cattle consume water to stay alive. But the vast majority of water used is to produce the animals’ feed. Feed crops like soya and hay need water to grow.

Just as with carbon emissions, it’s much more efficient for us to use that water to grow crops for our own consumption, than in growing them to feed to animals so that we can consume animal products.

Infographic of water use of different milks. All figures are in the table.

Does dairy or plant milk require more land?

To produce one litre of dairy milk, you need over ten times more land than for one litre of plant based alternative.

Livestock take up almost 80% of all agricultural land. Yet they provide less than 20% of global calorie supply and less than 40% of global protein. We use land to grow animal feed, as well as for them to live and graze on.

How we choose to use the land around us is going to become increasingly important in the coming decades. Every year, we convert more and more land away from natural ecosystems to produce food. This process is causing massive and catastrophic biodiversity loss, and is one of the biggest sources of greenhouse gas emissions.

As the population grows, we will need to make radical societal changes to feed everyone – rethinking our diets and our incredibly inequitable ways of trading and distributing food.

Otherwise, by 2050, we’ll need extra land equivalent to an area twice the size of India in order to feed everyone. This is a resource we just can’t afford to take from the natural world.

Rice milk – the plant milk with the lowest land demand – uses just 4% of the land required for the same amount of dairy milk. Soya milk uses just 7%.

Environmental factors for dairy and plant milks
  Greenhouse gas emissions in kg per litre of milk Land use in m2 per litre of milk Freshwater use per litre of milk
Cow milk 3.15 kg 8.95 m2 628.2 L
Oat milk 0.9 kg 0.76 m2 48.24 L
Soya milk 0.98 kg 0.66 m2 27.8 L
Almond milk 0.7 kg 0.34 m2 371.46 L
Rice milk 1.18 kg 0.5 m2 269.81 L

Figures from: Our World in Data, ‘Dairy vs. plant-based milk: what are the environmental impacts?

What is the most environmentally friendly plant-based milk?

Soya and oat milk are the most environmentally friendly plant-based milks. They have remarkably low impacts, compared to cow’s milk, whether you’re considering resource use or emissions per litre or by amount of calories and protein.

Switching to any plant-based milks is likely to have major environmental benefits, though, compared to consuming dairy.

In fact, as the table above shows, a portion of soya milk uses around 95% less land and freshwater than a portion of cow’s milk, and releases 70% less emissions.

How do plant and dairy milks compare on nutritional value?

Some milks have higher nutritional content than others. So, what does this mean in environmental terms?

Cow’s milk has the highest calories and protein content per serving (240ml). You’d need to consume about one and half times more soya or oat milk than cow’s to get the same amount.

But even once you’ve scaled the figures for this, oat and soya milk are still doing much better than cow’s milk in environmental impacts.

Plant and dairy milk compared by protein and calories
  Calories per 240ml Protein per 240ml
Cow milk 149 7.5 g
Oat milk 130 4 g
Soya milk 100 7 g
Almond milk 60 1 g
Rice milk 120 1 g

Figures from ‘A Comparison of the Nutritional Value of Cow's Milk and Nondairy Beverages

Oat milk would require 85% less land and freshwater for the same amount of protein and calories. Soya milk would require around 90% less land and almost 95% less water. Both would have about 50% lower carbon footprint.

For rice and almond milk, it’s a slightly more complex picture. They are considerably lower environmental impact options than cow’s milk when it comes to consuming calories – around 50% lower in terms of carbon emissions and 90% lower for land use. However, they fare much less well when it comes to protein. They would in fact have higher carbon and water footprints than cow’s milk, if you were trying to get the same amount.

If you want to find the milk with the lowest environmental impact compared to nutritional value, soya or oat would definitely be the ones to go for.

In our view, though, switching to any plant-based milk is likely to be a positive step, because you’re unlikely to be substituting calories and protein like for like. Most people will consume extra nuts, legumes or other nutritional plant-based food in order to make up any shortfall. These all have just a fraction of the emissions per gram of protein or kcal, compared to cow’s milk.

In practice, this means that switching to plant milk as part of a balanced diet with reduced meat and dairy will almost certainly significantly reduce your environmental impacts overall – whichever plant milk you choose.

If changing diets, it’s also worth remembering that you’ll get different vitamins and minerals from plant milk compared to cow’s milk. For example, soya, oat and almond milk all have more calcium per 100mls than dairy milk. They are also often fortified with vitamin D and sometimes vitamin B12.

What is the climate impact of dairy cheese vs vegan cheese?

While there are fewer studies comparing different kinds of cheeses, the environmental impacts of dairy cheese are far higher than vegan cheese.

According to a number of recent studies, plant-based cheese has around 70-80% lower emissions than dairy cheese. In one study, water use was found to be over 95% lower than that of dairy cheese.

Land use is also likely to be lower, given how inefficient it is to grow crops for cattle to eat, as well as give them space for living.