In early November 2021, thousands of people came together in Glasgow, at the 2021 United Nations Climate Change Conference, more commonly known as COP 26, to develop work on the 2015 Paris Agreement. The central goal of this agreement was to avoid driving up temperatures by more than 1.5° C relative to the pre-industrial level. This means that average emissions, measured in carbon dioxide equivalents per person annually, should be no more than about 2 tonnes. As average emissions are currently more than twice that, we are a long way from that goal.

I had the privilege to be able to attend COP 26, as a member of the Vegan Society. I heard many good things. The meeting rightly focused on the impacts of various industries and transport methods, but it – like all COP meetings that preceded it – largely ignored a big beast in the room: animal agriculture. Some side-events featured discussions of how the agricultural sector might be able to mitigate some of its impacts through technologies like precision farming, minimal tillage agriculture, and altering the diets of ruminants, for example through feeding them seaweed. Whilst agricultural technologies might be able to mitigate some impacts, I fear that this techno-fix approach might just carry us along the same path, perhaps delaying the catastrophic impacts of climate change by a few years.

Few sessions at the conference questioned the values that underlie our interactions with the planetary atmosphere. However, these values drive our technologies, and will continue to shape our future technologies. It is unlikely that we will reach the target without altering them. In relation to the values underlying the agricultural sector, hardly any attention was paid to the massive potential of a dietary shift towards veganism. For a number of reasons that I have documented at length in chapter one of my book ‘Animal (De)liberation: Should the Consumption of Animal Products Be Banned’, published with Ubiquity Press in 2016, non-vegan diets pose greater health risks resulting from climate change.

Key reasons why the consumption of animal products should be scrutinised in relation to the climate crisis

Whilst climate change is a complex issue that is caused by many different anthropogenic and other alterations to our atmosphere, it is worth looking at how vegan diets compare with other diets for some of the key gases:

• carbon dioxide (CO₂): Many non-vegan diets release more carbon dioxide into the atmosphere. One reason is that animals respire, where some of the carbon that is thus released might have been stored in plants if animals had not eaten them or had not been bred. Another reason is that such diets use a greater proportion of fossil fuels as much arable land is used to feed farmed animals, rather than to feed humans. Some of this land could capture carbon instead, for example through reforestation or afforestation. What compounds the use of chemical fertilisers to produce feed is that a lot of feed is grown far from where the animals who eat it live. Carbon dioxide is also produced by building, maintaining, and heating animal housing, as well as by transporting animals and the products derived from them. As slaughterhouses have become bigger and fewer in number in many places, animals are often reared far from where they are killed, turned into products, and consumed. Whilst many vegan foods are also produced in specialist housing, for example greenhouses, and the transportation, processing, and storage of fruits and vegetables also emit carbon dioxide, emissions from horticulture tend to be much lower. 
• nitrogen (N₂): In order for plants to produce nitrogen, they must get it from somewhere. Whilst they can get it from bacteria that fix nitrogen from the atmosphere, high yields are currently sustained mainly by the addition of nitrogen fixed through the Haber-Bosch process. This comes with a high energy cost. Currently, much of this energy is provided by burning fossil fuels, adding to the release of carbon dioxide. When applied to the land, much of this nitrogen is lost through volatilisation, leaching, soil erosion, and denitrification. This loss results in several problems, including the creation of nitrous oxide, which has a global warming potential that dwarfs that of CO₂. Non-vegan diets tend to be associated with greater nitrogen losses as many animals are fed arable crops that could have been consumed directly by human beings. As animal manure is frequently highly concentrated due to the industrialisation of farming, much agricultural land is supplied with much more nitrogen than plants can take up, resulting in large inefficiencies that trigger far-reaching ecosystem changes, including those associated with climate change.
• methane (CH₄): Non-vegan diets tend to release more methane into the atmosphere, mainly from enteric fermentation by ruminants and from manure. Bovine mass, or the weight of all cows and bulls on the planet, now exceeds human mass by more than 60 percent. Although methane does not remain in the atmosphere for as long as CO₂, its global warming potential is much greater. Reducing methane emissions can therefore buy us time to find answers to tackling other emissions.

Other stressors associated with many non-vegan diets

This, however, is not the full story. The fact that increasing numbers of people adopt non-vegan diets also makes us less capable of tackling climate change because of the following stressors: 

• phosphate loss: Plants require phosphorus to grow well. As many plants are consumed by nonhuman animals, rather than by people, non-vegan diets account for greater losses of phosphate in rivers and seas. As it is hard to recover phosphate from the sea, phosphorus shortages are usually addressed by mining phosphate rock, increasing transport emissions. High concentrations of phosphate and phosphate mining and quarrying impact negatively upon animal health. As reserves dwindle, human vulnerability increases further.
• water use and pollution: Many non-vegan diets use more water and pollute more water from manure and the use of fertilisers and pesticides. Many aquifers are being depleted unsustainably.
• ecosystem destruction: Non-vegan diets affect many ecosystems more negatively, undermining animal health. Many such diets include the consumption of animals who are reared on land or from crops, e.g. soybeans, grown on land that has been deforested to expand arable farming. Flood barriers are lost as mangroves are destroyed to produce shrimps and trawler fishing devastates oceanic ecosystems. As ecosystem degradation lowers agricultural yields, less space is left for reforestation and afforestation, and thus for carbon capture.
• negative physical health risks: Non-vegan diets cause more human disease as most new diseases are zoonotic. As non-vegan diets disrupt ecosystems more, the risks of releasing new diseases increase. Close contact between human and nonhuman animals increases infection risk, as does an increase in stress, including climatic stress. Slaughterhouse workers are frequently paid badly, marginalised, and working in poor conditions, increasing risks. Whilst the COVID-19 coronavirus originates from an animal market, many other human diseases are zoonotic. As many farmed animals experience poor health, particularly when reared in industrialised units, drugs are used lavishly. Antibiotic resistance is rising as many antibiotics are being used prophylactically and to promote animal growth. Whilst low consumption of some animal products may have no or negligible physical negative human health impacts, high consumption of many animal products is associated with significantly higher health risks compared to balanced vegan diets. As we struggle more with diet-related diseases, more emissions are released through our efforts to fight these, for example through the production of facemasks and new medicines.
• human hunger: Diets that include animal products can provide greater food security in some situations, for example through people eating products derived from animals who eat things, e.g. grass, that people cannot digest. However, many non-vegan diets contribute more to the health risks posed by human hunger and food insecurity as they tend to use more resources, for example water and soil. In a world with a rapidly increasing human population, many of these are becoming scarcer. As people experience greater food insecurity and hunger, they become less able to develop innovative ways to tackle the climate crisis.
• negative mental health impacts: The production and consumption of animal products also affect human and nonhuman mental health negatively. Slaughterhouse workers experience high levels of stress, which may explain to some extent why they are – in some places – hard to recruit. Many farmers struggle with the idea of sending animals to the slaughterhouse. Consumers of animal products experience guilt whilst vegans lack human companionship, for example through not being invited to parties or not wishing to be present.

In my next blog post, I will report on some discussions that were held at Glasgow on the contribution of the human food system to the climate crisis.