How much land does animal agriculture use?
Agriculture uses up 43% of the Earth’s ice and desert free land. Meat, dairy, eggs, and aquaculture collectively account for 83% of this agricultural land.1 80% of this land is used for grazing.2 As a result, almost half of all arable land is used to grow feed for animals. Despite using so much land, animal agriculture only provides 37% of the world’s protein and 18% of the world’s calories.1 This may come as a surprise, but urban and other developed areas only use up 1-2% of the Earth’s land, and hence are a relatively minor issue in terms of land use.3,4
Comparing the land use of plant and animal agriculture
A previous post about agricultural greenhouse gas emissions referred to a meta-analysis.1 In addition to emissions, this meta-analysis also compared land use for various foods. Below is a table comparing the most sustainable beef, cheese, pork, aquaculture raised fish, chicken, and eggs with the most sustainable tofu.
Comparison of land use between animal products and tofu per unit of protein1
As you can see, in general, animal-based foods require more land compared to tofu. Among animal products, red meats from ruminant animals like beef and lamb use the most land. Aquaculture, while using less land than traditional farming, has other negative environmental impacts as will explained in a future post. Nuts emit fewer greenhouse gases compared to animal-based foods, but they use slightly more land than chicken and eggs. Other legumes, fruits, vegetables, and grains tend to have lower land footprints than animal products. Similarly, the most sustainable dairy milk requires 3.7 times more land per liter compared to the most sustainable soy milk. No matter whether we compare land use per calorie or per gram of protein, animal products generally use much more land than plant-based foods.1
This data compared individual foods, but what if we compare overall diets? A study in the UK demonstrated that vegans used 75% less land compared to high meat consumers. It didn’t matter where the food came from or how it was produced, the study found similar results.5
How much do animals eat?
So then why is more land required to produce animal products compared to plant-based foods? As mentioned in a previous post about dietary greenhouse gas emissions, animals are quite inefficient from an energy perspective. When animals consume food, only a small percentage of the calories and protein within that food end up in the final animal product.1 So, compared to directly consuming plants, eating foods from animals leads to a lot of wasted nutrients. The ratio of nutrients in the animal feed to the nutrients available in the final animal product that humans consume is known as the feed conversion ratio. The higher the feed conversion ratio, the less efficient the animal is at converting feed into food. The table below shows the feed conversion ratio per unit of protein, per calorie, and per unit mass for various animal-based foods. It should be noted that the amount of calories and protein a in the feed is more important than the weight of the feed.
Feed conversion ratios for different animal products.
So from this data we can gather that 5% of the protein and 3% of the calories consumed by a cow end up in the final beef product.6,8 Eating beef or chicken is similar to throwing away 80-97% of our food while eating a meal. So wasteful. Animals utilise protein and calories not only for muscle (and hence meat) growth, but also to develop other organs. Additionally, animals expend energy while they are alive. To feed these extra calories and protein to animals, we grow more crops, and hence need to use more land. In general, the larger the animal, the more energy they require, resulting in a higher feed conversion ratio. Due to this, consumers changing their diets will have a more significant impact on reducing land use than companies improving their processes.1 The high feed conversion ratio of animals is a fundamental biological inefficiency.
We are paying the opportunity cost of not storing carbon
An opportunity cost is a potential benefit that we lose due to a decision that we make. For example, if we choose to work overtime, we may earn more money and gain brownie points with our boss, but at the same time, we miss out on the benefits of leaving early to spend time with family or friends. Because we can always use time or resources in a different manner, we are always paying an opportunity cost. Similarly, when we use land for a specific purpose, we lose out on the benefits from alternative uses of that land. For example, if we raise and consume animals, we miss out on the opportunity to store carbon dioxide on the land currently used for growing feed and rearing animals.
We must consider the opportunity cost of carbon storage.10,11 As mentioned in previous post about emissions, the opportunity to store carbon by using land in different ways is not a direct emission resulting from livestock production. Instead, emissions related to animal agriculture’s land use stem from deforestation that occurred in the past. So, it doesn’t make sense for us to repeatedly count those emissions every year. However, because we are not taking the opportunity to store carbon on that land, we will have to pay for that decision later in terms of future environmental and social impacts that the unstored carbon will cause. Also, the form of carbon that can be stored is carbon dioxide, which remains in the atmosphere for a long time. Many people believe that the emissions related to animal agriculture are limited to methane and nitrous oxide. However, animal agriculture also indirectly contributes to carbon dioxide emissions by diminishing the Earth’s capacity to store carbon dioxide.
If the entire world were to adopt the typical diet of developed nations, then on top of their already large land use, animal agriculture would need to utilise an extra area of land equivalent to the combined size of Africa and Australia to supply such a high demand for animal-based products.12 In contrast, if the entire world were to adopt a vegan diet, we would need 76% less total land and 19% less arable land. This freed up land would be roughly equivalent to the entire area of Africa. Allowing natural vegetation to grow on the unused land, instead of using it to produce food, could lead to the storage of approximately 8.1 billion tons of carbon dioxide per year for the next 100 years.1 This would offset 15% of current global greenhouse gas emissions.13 By 2050, if the entire world were to adopt a diet in line with the EAT-Lancet guidelines14, which is a plant based diet that only includes small quantities of meat and dairy, we could potentially store 332 billion tons of carbon dioxide. If the world were to adopt a vegan diet, we could potentially store 547 billion tons of carbon dioxide. Achieving this level of carbon storage is equivalent to reducing greenhouse gas emissions by 99-163% of the emissions threshold required to meet the 1.5°C global warming target. To further put this into content, that amount of carbon storage represents 9-16 years worth of global emissions from fossil fuels. Hence, this carbon offset would provide more time for other industries to reduce their emissions.
High-income and middle-income countries have the greatest potential for carbon storage.15 For example, if the United States replaced beef with beans and plant-based alternatives, it could achieve a 46-72% reduction in emissions compared to 2020 levels. In this scenario, 42% of U.S. arable land could be utilised for different purposes.16 Of course, it is not currently realistic for everyone to adopt these eating habits, but these examples effectively demonstrate potential outcomes and are useful for setting goals. In a future post, I will discuss food security and the feasibility of globally adopting plant-based diets.
Reforestation and rewilding
Reforestation is one of the most promising natural solutions to address climate change17,18 and is considered one of the most scalable approaches.19 The concepts of reforestation and rewilding share some similarities. Reforestation involves re-reestablishing forest ecosystems, while rewilding involves allowing any land or ecosystem we currently utilise to naturally regenerate. Hence, reforestation can be seen as a form of rewilding. Many ecosystems struggle to grow forests due to insufficient water and unsuitable conditions. So another example of rewilding would be instead of grazing animals on pastureland, allowing that land to go unused and regenerate. Through rewilding, plants and animals capable of surviving in that environment will take up residence on that land. Alternatively, we can introduce a variety of plants and wildlife to the rewilded land.
These ecosystems, including the roots beneath the soil and trees and plants above the ground, have the capacity to store carbon. Soil used for agriculture stores 25-75% less carbon than natural soil.20 Furthermore, by rewilding land that have previously been depleted by agriculture and allowing diverse plants to grow, the rate of carbon storage increases.21 As ecosystems approach maximum growth, the rate of carbon storage will naturally decrease. However, if we refrain from deforesting these ecosystems again, we can permanently store carbon there. It is important to note that reforestation is not the sole solution for carbon storage. Simultaneously, we will need technologies like carbon capture and sequestration. Nevertheless, reforestation is a crucial part of the solution.
So, is rewilding a waste of land because it does not directly provide any resources to humans? Not at all. Rewilded land provides us with indirect benefits because it can store carbon and improve biodiversity. Rewilding may not provide immediate economic benefits to people in the same way that agriculture does. However, we will benefit indirectly because we will live in a better and more resilient environment, which will help mitigate the effects of climate change. We often take the environment for granted, but it does hold economic value. Think of rewilding as an investment. However, to do this, we need to change our attitudes towards land use. The current economy supports extracting as much profit as possible from land. But there is no need for us to directly utilise all of the land on Earth. Instead, governments and landowners need to realise that land has value beyond just profit. Governments should consider land as a long-term investment and provide subsidies and incentives for landowners to engage in rewilding. But how can we realistically fund rewilding? First of all, instead of giving subsidies to animal agriculture, these subsidies can be diverted to farmers who rewild their land. Additionally, investments, donations, carbon offset schemes, fees for access to ecosystem services, and including taxes on certain foods are possible options tare feasible in different circumstances.22,23 We all benefit from our environment and so it only seems fair that pay a little to maintain it. However, these policies would also need to be fair for low-income individuals. The politics and economics of global dietary changes are complex and have many systemic barriers, which I will discuss in more detail in future posts. However, consumers have the power to reduce the demand for land by reducing their demand for animal products.
Both preserving existing forests and reforesting are important. However, growing new forests takes many years, so protecting existing forests is crucial. Restoring a forest to store previously released carbon is more challenging. Even though reforestation is one of the most effective strategies for mitigating climate change, climate change will limit our ability to reforest. For example, changes in temperature and rainfall due to climate change may hinder tree growth. Young trees may not survive as well due to droughts, heatwaves, wildfires, and other extreme weather events caused by climate change. Additionally, climate change will alter the effect of parasites and microorganisms on trees and will reduce biodiversity, making conditions less suitable for tree growth.18 To maximise the effectiveness of reforestation, we need to reforest before these adverse conditions become too pronounced.
Conclusion
Animal agriculture uses the majority of agricultural land, but it is an inefficient source of calories and protein due to low feed conversion ratio of animals. Typically, when we feed animals, protein and calories are wasted and hence we need to use more land to grow more feed. Plant-based protein sources like tofu generally require much less land compared to animal-based foods. In particular, consuming less beef and lamb would significantly reduce our dietary land use footprint. While we continue to allocate land for growing animal feed and raising animals, we miss out on the opportunity to store carbon on that land through reforestation and rewilding. Rewilding is one of the simplest and most practical solutions for removing carbon dioxide from the atmosphere. However, in order to do this, we need to save the land currently in use. In order to obtain that land, we need to reduce the demand for animal products by purchasing and consuming less. In the next post, I will discuss the leading causes of deforestation. Is it soy products, beef, or urban expansion?
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