A recent academic review from Cornell University, U.S., has compiled data on plant based meat and milks and their comparative impacts on the planet. Here’s what they found out.

In 2015, as part of the UN Paris Agreement, it was agreed by 196 nations at COP21 that global temperatures would not rise by more than 2 degrees Celsius above pre-industrial levels. 

Therefore, changes must be made to all sectors to reduce emissions, including the food sector. These changes need to occur in the agricultural industry, but dietary changes within the population are also required.

Carbon-intensive foods, such as beef and dairy, are large contributors of greenhouse gases (GHGs). One study found that across five environmental footprint indicators (GHG production, nitrogen and phosphorous use, land use and water consumption), the production of animal-sourced foods accounts for 72–78% of total agricultural emissions. 

As people become more aware of the impacts of dairy and meat-based diets, meat-free alternatives are becoming more widely available. While ingredients like pulses and lentils form the basis for traditional meat-free dishes, they can be challenging to prepare when using raw ingredients.

Luckily, plant-based alternatives that mimic the taste and texture of meat products — think burgers and sausages — are easy to prepare and are part of an expanding market. These are typically soy-based and generally classed as ultra-processed foods. But are these handy options better for the climate?

Comparisons of environmental impact

Beef and dairy have a significantly greater impact on the environment than plant-based alternatives across all environmental footprint indicators, while the impacts of poultry and pork are comparatively low. 

A recent review paper conducted by researchers at Cornell University compiled data from various studies comparing GHG, land use and water usage (including irrigation and processing) per 100g of protein for different meats and plant protein foods. 

Most notably, the GHG emissions from beef production are 13 times those of plant-based meats, whereas the emissions from pork and poultry are only two to three times greater. 

Similarly, the land use of beef is 59 times that of plant-based meats, and its water usage is about four times greater. Again, the land use of pork and poultry is more comparable to plant-based meats, at six and four times greater respectively.

Dairy herds have a significantly lower environmental impact compared to beef herds across all environmental indicators. Additionally, beef derived from dairy herds exhibits a reduced impact due to the efficiencies in milk and beef co-production.

Still, dairy milk has also been found to have a greater impact on the environment than plant-based alternatives, though the extent depends on the environmental indicator, the type of milk and the regional production system used. 

When evaluating the environmental impacts of various milk products, considering the entire lifecycle from the farm to packaging with a standardised measure of 1 litre, GHG emissions from dairy milk are three to five times greater than those from plant-based alternatives (such as soy, almond, oat and rice). Moreover, the land use per litre is found to be between 12 and 26 times higher for dairy milk.

Water use is also greater for dairy milk, ranging from twice as much as for rice and almond milk to 23 times for soy milk. 

However, these results do differ depending on how products are compared. For example, when using 1 kg protein to compare environmental impact, almond milk has the highest environmental impact across all categories.

Environmental impacts across supply chains

Comparing environmental impacts across supply chains can be challenging due to the diverse range of raw materials, processing methods and distribution systems involved in both animal and plant-based meat and dairy products. 

For animal products, this can include slaughtering or milking, before being processed and packaged prior to retail distribution. 

The raw ingredients of plant-based products require industrial processing and often the addition of other ingredients, all of which contribute to the environmental impact of the final product. 

Across the whole supply chain, from farm to retail, approximately 60% of GHG emissions from beef production come from the livestock stage; from fermentation, pasture fertilisation and manure.

Land use change from burning or deforestation accounts for another 23% of GHG emissions from beef production. However, it’s worth noting that only 14% of cattle feed consists of food that could be eaten by humans, whereas 64% of poultry rations globally consist of grains that could be consumed by humans instead. 

Livestock contributes to 14.5% of total global GHG emissions. While well-managed grasslands may allow beef herds to achieve neutral or negative carbon emissions, this has a limited impact overall. This is because 96% of beef in the United States is finished in fossil fuel-reliant feedlots, offering no mitigation against emissions.

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GHG emissions from plant-based meat production are much lower. It’s hard to provide an exact figure, different processing methods may be used and sometimes GHG emissions data are lumped together with CO2 emissions used as an umbrella term. 

Critically, as noted by Dr Boiteau, one of the authors of the Cornell paper, as of yet there have been “no larger studies or systematic reviews that would provide a broader perspective on the environmental impacts of plant-based meat or milk production (from raw and intermediate ingredients through processing, packaging and distribution).”

A stainless steel vat filled with hundreds of white, spherical soy beans.

A vat of soy beans (Remi Chow/Unsplash)

However, a non-peer reviewed article estimated that plant-based meat produces 30-90% fewer GHG emissions than conventional meat. Production of the raw ingredients and transport to processing facilities accounts for about 40% of these emissions, with processing accounting for approximately 45%.

Interestingly, there seems to be little difference in GHG emissions between the different plants commonly used in plant-based meats when considering all of the raw ingredient inputs. 

There is a similar story when comparing dairy milk with plant-based alternatives. 72% of GHG emissions for dairy milk come from the preprocessing stages of production. In contrast, just 28% of GHG emissions come from the preprocessing stages of soy milk production. Most GHG emissions associated with soy milk come from electricity requirements at retail. 

The impact of retail electricity on GHG emissions should not be considered in isolation, as there is a potential bias towards higher perceived electricity needs for more shelf-stable (plant-based) products, possibly creating the impression of increased consumption because of their extended shelf life. For example, soy milk typically has a longer shelf life than dairy, so can stay in the fridge longer, using more energy in the supermarket.

So, plant-based is better, right?

When looking solely at GHG emissions, it’s fair to say  that plant-based meats are, overall, better for the climate and environment.

Unfortunately, it’s not that simple, many other factors must be considered before we can state that plant-based meat is better for the planet than animal meat. 

Land use is one such consideration. Only half of all current arable land used by livestock is suitable for converting to cropland; livestock is often put onto land because crops cannot be grown or harvested. In theory, this is not a concern in terms of producing enough food to feed the global population; if everyone followed a vegan diet, agriculture would only need 25% of the land it currently uses. 

However, a switch to a plant-based diet would need to be carefully managed, since many of the world’s poorest rely on managed livestock grazing for their livelihoods. 

The impacts of plant-based foods on biodiversity are also of concern since the crops used are typically grown in monocultures. Local biodiversity, both above and below ground is lost due to chemical or mechanical disruption. 

So, while the production and consumption of plant-based meat alternatives sourced from peas or soy avoids direct harm to animals, it nevertheless contributes indirectly by causing the disruption and destruction of habitats.

Finally, the impacts of traditional vegetarian and vegan diets cannot be ignored. While farming emissions of fruits, vegetables, pulses and wholegrains are present, they do not produce the  processing emissions associated with plant-based meats.

In short, evaluating the environmental impact of plant-based foods and milk products versus their animal-based equivalents is intricate. We tend to know what’s bad for the planet, but knowing what’s best for it is a whole different ball game.