How Farming and Production Affect Meat & Dairy Emissions
A common claim by meat advocates is that, under the right farming conditions, livestock rearing can have a minimal—or even beneficial—impact on the climate. This, of course, is entirely dependent on how farming and production affect emissions from meat & dairy.
It is true that emissions from livestock production vary from country to country and from farm to farm, a researcher at the University of Oxford and leader of the Food Climate Research Network (FCRN) states that grouping together UK, U.S. and South American production is an inaccurate approach because they all have very different systems of production.
Emissions from production depend on a number of factors, including how much and what type of land has been converted, the type and amount of fertilizers used, animal welfare and upkeep—to name a few.
One factor that can influence total emissions is the type of feed given to cattle. Different types of feed produce different amounts of methane: for pasture, the fraction is around 6% of calories burped as methane. For higher quality feeds like soy, the fraction is more like 3%—however, these feeds can also contribute to deforestation.
Even when the range of different production systems are considered, emissions from meat and dairy products still tend to be larger than those from plant–based foods. Evidence suggests that plant–based foods emit fewer greenhouse gases than meat and dairy, regardless of how they are produced.
Based on a 2018 study published in Science magazine, it draws on production emissions data from more than 38,000 commercial farms in 119 countries. On the chart below, the height of the curve represents the amount of production globally with that specific footprint.
On average, beef and lamb production have the highest carbon footprints of all the foods. However, the lowest–emitting beef has a carbon footprint that is a similar size to the average 100g–portion of chicken or eggs.
The lowest–emitting beef tends to come from the dairy sector. Beef from dairy farms has a footprint that is around 60% lower than that of dedicated beef herds. This is largely because dairy production systems tend to be more efficient. It is sometimes claimed that rearing cattle on grasslands can stimulate soil to uptake more carbon, helping to reduce the effects of climate change.
However, a 2017 report (pdf) by the FCRN at the University of Oxford found that grass–fed cows release more greenhouse gas emissions through belching and manure than they are able to offset through boosting soil carbon levels. This means that grass–fed beef is still a net contributor to climate change.
The analysis also shows that production emissions from farmed shrimp and fish vary widely, with a small proportion of producers exhibiting very high emissions. The highest emissions come from industrial–scale aquaculture, which is popular in some parts of Asia.
The range of emissions for pork, chicken and egg production are smaller than for beef and lamb. This is because intensive systems for the production of these foods do not tend to differ much from region to region.
For some plant–based foods, production emissions can be below zero. This means that the production of these foods removes CO2 from the atmosphere. This is particularly true for nuts because some nut trees can be incorporated onto agricultural land—increasing its uptake of CO2.
“Plant–Based” Meat and Dairy Alternatives Have a Lower Climate Impact
From vegan “burgers” to oat milk, plant–based alternatives to meat and dairy have seen a huge surge in popularity in North America and Europe. It is too early to say how these products could affect future food emissions, but they have broadened the choices available for those looking to reduce their meat consumption.
The chart below compares the average greenhouse gas emissions created from a kilogram of beef and two plant–based alternatives, including the Beyond Burger and the Impossible Foods burger. The data comes from several “life cycle assessments”, which consider the emissions created by every stage of production, from farming to processing and transportation.
The chart shows that the carbon footprints of both the Beyond Burger and the Impossible Foods burger are around 20 times smaller than that produced by the same amount of beef. The difference in emissions stem mainly from production.
The Beyond Burger is made from pea protein, while the Impossible Foods burger is made from soy and potato protein. Both products also contain high amounts of vegetable oils and fats. The cultivation of these vegetables produces relatively fewer emissions than beef.
It is worth noting, however, that plant–based burgers do not deliver additional health benefits when compared to meat because they contain lots of saturated fat and salt. The Impossible Burger is sold in the U.S., Hong Kong, and Macau.
Plant–based alternatives to milk have also risen in popularity. A 2019 survey found about one in four British citizens now drink plant–based alternatives to dairy. For 16 to 33 year–olds, it is one in three.
The chart shows how average emissions from plant–based milk are around half that of dairy milk. Again, this is largely down to differences in production emissions. The emissions from dairy milk are due to a combination of factors—burps, feed and manure—whereas the emissions from producing plant milk ingredients are so low that packaging, transport and refrigeration cause much of their emissions.
The latest academic studies found that plant milks create less than half the emissions of dairy milks, but these could be reduced even further by using renewable energy in production and when recycling the packaging.
The chart shows that almond milk has the smallest carbon footprint. However, the production of almond milk requires large amounts of water. In California, where 90% of the world’s almonds are produced, it has also been linked to unsustainable pesticide use, declining bee populations and a perpetual drought. The plant–based alternative with the second smallest footprint is oat milk. Oat milk also has small land–use impacts and water requirements, when compared to other plant–based milks.
Is Eating “Local” Really Better
Advocates for meat–eating often argue that consumers can evade the environmental consequences by choosing products made in their country of origin. It is argued that “local meat” has not had to travel by plane or ship before it arrives on the plate and, therefore, must be more environmentally friendly than other foods from further away.
However, research shows that the contribution of “food miles” is relatively small in comparison to other factors, such as production. Food miles make a difference, but they tend to be relatively small compared with the other inputs. The chart below shows how much travel emissions contribute, on average, to the total greenhouse gas emissions per kilogram of different foods.
The chart demonstrates how just a small fraction of food emissions come from transport and that, in general, total emissions are more influenced by food type (animal–based or plant–based). The reason why transport emissions are relatively low is that most food is transported by shipping or rail.
Train transportation is really very efficient and shipping is also relatively efficient. And probably more efficient than a small local farmer driving three hours with a pick–up truck. The chart below gives a breakdown of how food is transported. The metric—“food miles”—is calculated as the distance each transport method covers multiplied by the quantity of food transported by mass.
Global Food Miles by Transport Method
Food miles do make a difference to total emissions for the small fraction of products that are transported via air. Transporting food by air emits around 50 times as much greenhouse gases as transporting the same amount by sea. This is because air travel is particularly polluting and also unable to deliver large quantities of food, making it relatively inefficient.
Products that are air–freighted tend to be those that perish quickly, including some fresh fruit and vegetables, according to a food scientist at the University of Manchester. It is hard to know which foods have come by air.
As a rule, things that can last a few weeks in storage will travel by ship, such as apples, oranges, bananas and dried pulses. However, perishable fruits, such as strawberries, raspberries and blueberries, are likely to have been flown, if coming from another continent.
A breakdown analysis by the Greenhouse Gas and Dietary choices Open source Toolkit (GGDOT)—found that, in the UK, air–freighted asparagus has a carbon footprint that is around six times higher than locally–produced asparagus.
It is also worth bearing in mind that some locally reared meat can have a “hidden transport cost”. This can be the case when animals are fed on grain imported from other countries. A study published in 2016 found that more than half of the UK’s animal feed is imported—mostly from South America and the European Union (EU).
Imported animal feed can have an even larger climate impact when it is linked to deforestation in tropical regions. A study published in 2020 estimated that up to one fifth of the Brazilian soy that is exported to the European Union is linked to illegal deforestation. Soy is commonly used to feed livestock.
Sources:
Interactive: What is the climate impact of eating meat and dairy?
https://interactive.carbonbrief.org/what-is-the-climate-impact-of-eating-meat-and-dairy/
by Daisy Dunne, Published: 14/09/2020
Design credit: Tom Prater and Joe Goodman.
Video credit: Martin Harvey
Data Sources:
Poore & Nemecek (2018)
https://science.sciencemag.org/content/360/6392/987
Heller & Keoleian (2018)
http://css.umich.edu/sites/default/files/publication/CSS18-10.pdf
Khan et al. (2019)
https://impossiblefoods.com/mission/lca-update-2019/