Why reducing beef is good for the climate
In carbometrix, we measure emissions from the 3 scopes. And we pay particular attention to the employee meals. Why? because it is a lever of action that is available for all employees of your company. And because it can really have an impact…
When choosing our meat, dairy, and eggs with the environment in mind, we tend to focus on local, organic, and pasture-raised or free-range labels, and view intensive systems as more destructive of the planet. But is that really the most effective choice ? What makes animal products polluting ? Why should we avoid beef and prefer chicken ? What does organic mean in terms of greenhouse gas emissions ?
The markets for animal products are absolutely gigantic: 33 billion chickens, 1 billion cattle and 780 million pigs are currently roaming the earth. Contrary to popular belief, these are very domestic markets: 90% of livestock and livestock products (meaning meat, dairy, and eggs) are produced and consumed in the same region of the world. However, many inputs of the supply chain are imported: farms purchase animal feed and fertilizers from a much more globalized market. Together, China, the European Union, the United States, and Brazil produce 58% of all animal feed on the market. This means that our products have good chances of being produced regionally, but that doesn’t guarantee that the inputs they used were local.
Why do animal products emit greenhouse gasses?
There are many sources of greenhouse gas emissions in the life cycle of animal products, from the production of agricultural inputs to the food on our plate. We tend to focus on transport and packaging, because they are the most visible and the ones we can directly control, but they are very minor compared to other sources. Here are the real culprits.
Enteric fermentation – or cow farts – is the main source of greenhouse gas emissions from livestock
Behind this technical term is something we all know about without really measuring how important it is: cow farts and burps! Animals, and especially ruminants like cattle and sheep, produce methane when they digest fibrous foods. This effect depends on the quality of their feed: lower feed quality means higher fiber content, and therefore more methane emitted during digestion.
Enteric fermentation is highest for cattle, and especially dairy cattle, who have lower feed quality overall. A dairy cow in the United States emits an average of 138 kilograms of methane (CH4) each year from enteric fermentation. In terms of greenhouse effect, this is equivalent to 3,864 kilograms of greenhouse gasses (also called CO2-equivalent, or, CO2e). Meat cattle in the US, on the other hand, emit 1,782 kilograms of CO2e per head and per year.
But this does not mean that beef emits less greenhouse gasses than milk or cheese! Let us consider an average dairy cow in a conventional american system: it will live for a total of 5 years, and produce around 29,710 liters of milk during its productive lifespan (3 years). This means an average production of 5,942 liters per year of her total lifespan, which brings us to around 0.65 kilograms of CO2e due to enteric fermentation per liter of milk.
For meat, on the other hand, the average beef cattle in the United States will live 1.5 years and give 175 kilograms of meat. Taking into account that 21% of the beef supply in the US comes from dairy cows, we reach 35 kilograms of CO2e from enteric fermentation per kilogram of beef.
For pigs and chickens, enteric fermentation is much lower. Pigs emit only 42 kilograms of CO2e per animal and per year. With a lifespan of 6 months and a meat weight per swine of around 72 kilograms, this gives us 0.5 kilograms of CO2e from enteric fermentation per kilogram of pork meat. Chicken meat only emits 0.01 kilogram of CO2e in enteric fermentation.
Land use change can be a major climate issue in countries with deforestation and dense vegetation
How does the carbon cycle of soil work ? If you plant a tree, it will grow by taking carbon from the soil and the air and stocking it within its organic matter. As long as the tree lives, it is a carbon sink. If the tree dies, it will decompose and transfer its carbon back to the soil and the atmosphere. If you cut down the tree and make an object out of it, the carbon will be stored in this object for its lifespan, and then eventually be burned or decomposed.
The takeaway is that only planting definitive forests – where trees will be replaced, either artificially when cut or naturally when they die – can store carbon. When we cut down a forest to make space for cropland or pasture, we release stored carbon into the soil and the atmosphere. This is why land use change must be accounted for when calculating the impact of products on the climate.
Land use change emissions are the amount of greenhouse gasses freed into the atmosphere by converting one hectare of natural land into agricultural land. The denser and the richer the vegetation on the natural land, the higher the carbon cost of turning it into pasture or cropland. This is why we often hear about the impact of agriculture in Brazil: this is a country where agricultural land is currently expanding and the natural land is very rich. India, on the other hand, has rich forests, but its agricultural land is not currently in expansion, so on average, a product coming from India will not have been responsible for any deforestation.
The countries where land use change emissions per hectare are the highest are Indonesia, Brazil, Argentina, and other South American, Central African and Asian countries in the equatorial and tropical regions with dense forests. So when you purchase any product, it is preferable to avoid these countries, or look for guarantees that the product did not lead to any deforestation.
Manure management systems emit large quantities of methane and nitrous oxide
Farm animals produce manure. This manure contains undigested nitrogen from their feed, which will be partially released in the form of nitrous oxide – another greenhouse gas – during decomposition. The decomposition of manure also releases methane. These emission processes are still the object of scientific studies, but we know that they vary depending on the animal, the region’s climate, the type of farming system, and the method used to store and treat the manure.
The main manure management methods, accounted for by the IPCC Guidelines for National Greenhouse Gas Inventories, are anaerobic lagoons, slurry storage in tanks, solid pile storage, dry lot storage, daily spread on agricultural soil, biogas production by anaerobic digester, and burning of dried dung for fuel. The differences between systems are huge, varying ten-fold between daily spread and anaerobic lagoons!
Overall, anaerobic lagoons are the most emissive manure management system: the anaerobic (oxygen-deprived) digestion of organic materials underwater by microorganisms produces biogas, composed mainly of methane and carbon dioxide. In the case of biogas production in manure digesters, this gas is captured for use as fuel, but in anaerobic lagoons it is released into the atmosphere. Story storage is the second most emissive system, since it also involves underwater decomposition of manure.
The warmer the region’s climate, the more emissions will be caused by the same manure management system. This is due to the intensity of microorganism and bacterial activity that depends on temperature.
In temperate regions of the United States, manure management emissions are highest for dairy cattle, with a whopping 3175 kilograms of CO2e per animal and per year! Second place goes to beef cattle with 273 kilograms, and swines come in third emitting 100 kilograms per animal each year. Laying hens emit 4.1 kilograms of CO2e per year and per animal, while broiler chickens emit 3.51.
But once again, these numbers must be brought back to consumer products in order to draw a comparison in the supermarket! In the same system as above, manure management emissions for dairy cattle give 0.53 kilograms of CO2e per liter of milk produced, while meat cattle manure emits 7.8 kilograms of CO2e per kilogram of meat, and one kilogram of pork represents 1.2 kilograms of CO2e from manure management. One egg is 20 grams of CO2e from manure management, while one kilogram of chicken meat is 500 grams.
Once again, beef is the big loser in the climate-conscious ranking, and we recognize the pattern of the kilogram of meat being more carbon intensive than the kilogram of milk or egg.
Animal feed production is carbon intensive because of fertilizers, land use, and energy consumption
Animals mainly eat soy and maize, in the form of grains and byproducts from human food industries: pressing soybeans into oil for human consumption leaves the fibrous parts, called soy meal, which can be fed to animals. Other ingredients are added to feeds: other grains and legumes, sugar beet molasses, skimmed milk, … Ruminants also consume grass when placed on pasture. Other forms of grass feed can be elaborated by drying the grass (hay) or fermenting it (silage).
These feeds emit greenhouse gasses because the grains need to be grown, all the ingredients processed, and the ingredients and finished products transported. For more details on main sources of emissions for growing crops, you can read our article on plant agriculture.
This is where organic agriculture comes into play. Organic means that the farmers use less chemical inputs: less antibiotics, feed that is pesticide-free, organic fertilizers… Therefore, less emissions are caused by the production of pesticides and fertilizers, and feed emissions are lower. However, this effect is slight, as the main emissions from feed production are land use and nitrogen application (which in the case of organic agriculture will be achieved similarly using animal manure or compost).
Why should we avoid beef and prefer chicken?
Overall, meat emits more greenhouse gasses than equal weights of milk or eggs for each emission mechanism. Among meats, beef is dead last in climate-adequacy, and by far: if you must avoid or reduce one food for the climate, this is the one! Pork meat has lower emissions than beef, but it is still more carbon intensive than chicken, our climate champion.
Organic agriculture will reduce the footprint of animal feed, but feed has a relatively small contribution to the total footprint.
Pasture-raised animals will eat less processed feed and therefore have lower emissions from feed production, but they will also use more land surface – and therefore possibly increase emissions from land use change, depending on the country of production – and have higher enteric fermentation emissions because of lower feed digestibility. Therefore, pasture-raised livestock is not less carbon intensive than conventional.
Local animal products will guarantee very low land use change emissions if you live in a country with little deforestation or no primary forests, but the impact of transport in the carbon footprint of animal products is largely neglectable next to agricultural sources. Therefore, locality is not a guarantee of climate-consciousness.
The agricultural sources developed in this article account for an overwhelming majority of the total footprint on animal products, as shown in the graph below.