Since the emergence of our species, procuring food has been one of the main interactions between humans and the natural environment. It is perhaps the most important force shaping the development of new technology, human behaviors and cultural attributes. From hunting and gathering to e-agriculture, the relationship between humans and their food systems is constantly evolving. As the speed and intensity, we generate food at increases, so do the impacts it has on the living world.

A short overview of agricultural history

Initially, humans were very aware that they are active participants in food systems. Hunter-gatherers had to be aware of plant species to ensure they aren’t eating anything poisonous, and they had to understand animal behaviors to hunt them effectively. This tight functional and cultural tie between humans and their food systems ensured sustainability and made intergenerational responsibility a societal imperative. They were too aware that if they drive a prey species to extinction or overharvest staple plants, they too will suffer. Many indigenous cultures place humanity as part of natural cycles as opposed to outside of them, in contrast with the Western idea of civilizing, conquering and/or taming wild lands. 

As humanity’s understanding of animals and plants progressed, horticulture and pastoralism became more and more common. Recent studies and books, such as “The Dawn of Everything” by David Graeber and David Wengrow, argue with archaeological evidence that the line between hunter-gathering, horticulture and agriculture was a lot thinner than we imagine, with many cultures undergoing seasonal shifts in their production method and social structure. However, all over the world, agricultural communities began forming and being tied to the land.

As society changed, so did our view on the environment. We went from relations of commensalism or mutualism, where the wellbeing of our surroundings was seen as beneficial, to a form of competition. Agricultural monocultures focus on a few crops, and everything else becomes a pest that needs to be killed. Forests, rather than sources of berries, nuts, fungi and wild game, become fields waiting to be cleared. Swamps, rather than staying reservoirs of biodiversity and carbon sinks, are drained and turned into fields. Grasslands, tundra, rainforests, coasts – every piece of land that can be used for agriculture is ravaged to support the expansion of kingdoms, pay taxes, feed armies and enrich merchants. 

In Medieval times, many properties were still administered in a communal way, called common land – large fields which could be owned by an individual or group of people, but entire villages (“the commoners”) were allowed to benefit from them, such as by bringing their animals to graze on common pastures, by collecting wood and kindle from forests or by cutting turf. This incentivized people to collectively care for their environments. While the “tragedy of the commons” tries to explain the end of collaborative economies and the emergence of private property as inevitable, the real driving forces were a lot more complex, with enclosures being a key factor which gave rise to modern agricultural practices. Enclosing a piece of land meant depriving commoners of their rights of access and privilege, which on hand increased efficiency but also fostered social unrest and gave rise to the separation between humans and their food systems, eventually leading to today’s environmental issues. 

In modern society, very few of us have any direct link with food production. Rather than active producers who are aware of their impact, we are passive consumers. We eat food that is grown, packaged and processed hundreds or even thousands of miles away, completely disconnected from the natural range and annual cycles of our crops. Big agricultural conglomerates and corporations see food as a product that can be sold, and often have no regard for natural cycles or sustainability in the real sense. Practices such as permaculture or organic farming are still not widespread, and many doubt that they’d be able to feed humanity.

Intensive agriculture does have some advantages – you can enjoy fresh strawberries at any time of the year! You can eat a light quinoa salad for breakfast, some slow cooked ribs for lunch, a rice bowl for dinner while living in London, tens of miles away from the nearest meat farm and continents away from the quinoa and rice farmers. You can enjoy a selection of spices, desserts and delicacies year-round at affordable prices, living a culinary life more luxurious than many ancient kings and emperors could have dreamed of.

The impacts of human food systems on the environment

This system, focused only on profits, has several drawbacks. Food impacts the environment in several ways. The entire supply chain, from growing and harvesting to processing, packaging, transporting, marketing, consumption, distribution, and disposal of food and food-related items, fails to view environmental wellbeing as a priority. The environmental and social costs are hidden away from customers. The low price of food is paid through degraded soils, clearcut forests and species driven to extinction. The year-round availability of your favorite fruits and vegetables also brings climate change, increased chance of extreme weather and thus future damage to crops.

Globally, industrial agriculture is one of the most damaging human actions towards the environment. Growing plants at our current intensity results in enormous water fertilizer use, while meeting meat demands necessitates unsustainable amounts of feed. The results? Degraded soils, exhausted groundwater supplies, greenhouse gas (GHG) emissions, animal suffering, runoff which destroys the ecosystems of rivers, deltas and coasts. 

The constant need for economic growth and increased profits drives farmers to either intensify their operations or expand their land use. The latter results in increased deforestation or destruction of other natural ecosystems, such as grasslands or marshes. Even when patches of forests are conserved, their resilience is greatly reduced due to the “island effect”. 

The natural biogeochemical cycles cannot adapt to the increased amounts of chemicals. The nitrate and phosphate cycles have been thrown out of harmony, with potentially disastrous consequences. Humans make processes that should take decades to happen unfold within days. The threats to global climate and biodiversity cannot be underestimated and must be looked at in detail.

Agricultural contributions to climate change

Before looking at how exactly producing food results in climate change, we need to understand the concept of greenhouse gases. GHGs are capable of absorbing and emitting radiant energy within the thermal infrared range – essentially storing and then releasing energy from the Sun. The primary greenhouse gases in Earth’s atmosphere are water vapor (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ozone (O3). Their balance is vital for life on Earth, and without them humans would find the planet essentially uninhabitable: the average temperature of Earth’s surface would be about −18 °C, rather than the present average of 15 °C. However, by increasing the concentration of GHGs in the atmosphere, humans are warming up the planet. Energy that would normally be reflected into outer space is kept and released within the Earth’s atmosphere, which is already having dire consequences on the global climate and everything that depends on it.

According to a 2019 study by the IPCC, 22% of human emissions came from the Agriculture, Forestry, and Other Land Uses Sector (AFOLU), with food production being considered the main driver. This means that almost a quarter of all human emissions are somehow tied to food production. Meat production is considered the most environmentally damaging part of agriculture, with 60% of agricultural GHG emissions being a result of it.

The main GHGs resulting directly from agriculture are methane (CH4) and nitrous oxide (N2O), while land use change mostly contributes CO2. Because these gases absorb energy differently and stay in the atmosphere for different times, a way to measure them was designed: the Global Warming Potential (GWP). Using this measuring method, methane is 27 to 30 times more potent than carbon dioxide, and nitrous oxide a whopping 273 times, meaning that even relatively small quantities of them can have the same climatic impact as burning oil or coal. For a stable climate, GHG’s must be at the very least brought down to the point where they are equal with the capacity of natural and artificial systems to reabsorb them – the fabled “net zero”. Even then, there is a form of inertia to our climate: due to the transfer of heat taking time, there is a significant delay.

Methane from agriculture: meat and rice

Methane emissions are the result of a number of separate processes. Animal agriculture is the main source of it. Animal digestive systems can be split into two main categories, ruminant and monogastric. Ruminants, mainly cattle raised for beef and dairy, have high methane emissions and are less “efficient” when it comes to converting feed into useable products. Monogastric animals, such as pigs and poultry, emit significantly less methane and are thus more “environmentally friendly” by comparison. The second biggest source of agricultural methane is traditional rice cultivation, responsible for more greenhouse gases than any another plant food. Its impact on the climate is the same as the combined emissions of all aviation, and was estimated in 2021 to be responsible for 30% of agricultural methane emissions and 11% of agricultural nitrous oxide emissions. This is due to the long-term flooding of rice paddies required for cultivation, which inhibits the soil from absorbing atmospheric oxygen, a process causing anaerobic fermentation of organic matter in the soil. Overall, rice production releases about half as much CH4 as beef production.

Nitrous oxide from agriculture: fertilizers

Nitrous oxide emission comes from the increased use of synthetic and organic fertilizers. Fertilizers increase crop yield production and allow the crops to grow at a faster rate. They are vital for our perception of prosperity, with supermarkets vegetable and fruit aisles that are always full. Agricultural N2O emissions represent 6% of the greenhouse gas emission in the United States and have increased in concentration by 30% since 1980. While 6% may appear to be a small contributor, nitrous oxide emissions have significantly more powerful warming potential than carbon dioxide emissions, as previously mentioned. 

Mitigations and solutions for CH4 and NO2 emissions

Methane could be reduced through a number of means. On the individual level, vegetarian and vegan diets (or simply reducing meat and dairy consumption as much as possible) are often suggested as the best option. From a wider perspective, investing in meat alternatives and lowering subsidies for animal farming are both options worth looking at. However, government involvement in agricultural policy is limited. The high demand for agricultural products like corn, meat, and milk means that officials are reticent to regulate these products, as it could result in increased prices for staple foods and decrease the public’s trust in them. Some government initiatives try to address the issue from the other end: food waste. An example is the United States Agency for International Development’s (USAID) global hunger and food security initiative, Feed the Future project, which is addressing the sustainability of food systems by looking at food loss and waste. Rotting food also produces methane, and by reducing food waste, we could make significant progress in reducing emissions without increasing food prices and ensuring food security.

For nitrous oxide, different management practices such as water conservation through drip irrigation, nutrient monitoring to avoid overfertilization, and the use of a cover crop in place of fertilizer application may help in reducing the level of emissions. This is challenging and often either cost or labor intensive, with many organic farms requiring the help of a significant number of volunteers. When this is not possible, farmers must sell their products at premium prices. Therefore, we must think about systems, not just about isolated consumers. If we see climate change as a problem caused by individual behaviors rather than systemic issues, we will start accusing poor people of contributing to global warming by not buying organic vegetables which are significantly more expensive than their conventionally grown counterparts.

Land use change

The planet’s major changes to land cover since 1750 have mostly resulted from deforestation in temperate regions, where forests and woodlands were cleared to make room for agricultural fields and pastures. One significant effect is that the albedo (the capacity of the Earth’s surface to reflect light, and thus energy, back into space) of the affected area changes, which can result in either local warming or cooling effects, depending on local conditions. 

Deforestation also affects regional carbon reuptake, decreasing the capacity of regions to absorb CO2, which in turn results in increased concentrations and higher net emissions. Land-clearing methods such as slash and burn exacerbate these issues by burning biomass, which directly releases the greenhouse gases “entrapped” within forests. Particulate matter such as soot is released into the air, harming the health of both human populations and wildlife. 

Soil and erosion

Land clearing can also destroy the soil carbon sponge. Healthy soils are significant carbon stores. Forests, grasslands and wetlands are good covers, providing them with biomass to recycle and store and protecting them from erosion. Without cover crops, they are exposed to water and wind, which decreases the services they provide for humans. Surface runoff is another factor that needs to be considered. It is a result of water accumulating faster than the soil can absorb it. Improperly maintained lands have poor absorption capacities, which results in spills and even flooding. In the period following harvests when soil is exposed, this is a great issue. Crop rotation is necessary for soils, but some farmers choose to not use cover crops, letting the soils exposed, which increases the effects of surface runoff. Pastures degraded by overgrazing encounter similar issues: the soil lacks cover and is compacted due to animals threading over it. 

Thus, during heavy rain, water builds up and flows to available reservoirs, such as rivers and lakes. It carries with it various pollutants, such as fertilizers, animal manure and pesticides. This makes the water rich in nutrients and results in algal blooms, exhausting oxygen supplies and damaging the local ecosystems. Concerns about such problems are particularly acute in the case of CAFOs (concentrated animal feeding operations). When there are high concentrations of insecticides, local insects can suffer mass die-offs, resulting in cascading effects along the food chain. Other chemical-sensitive animals, such as amphibians, can have their hormonal cycles disrupted.

Solutions for fertilizer/manure runoff

As previously mentioned, drip fertilizing is a practice which uses significantly less water and fertilizer. Its targeted nature means that, in combination with other measures, the fertilizer content of runoff can be greatly reduced.

Animal manure provides environmental benefits when properly managed. In nature, it is a key part of several nutrient cycles. However, human industrial farms have significantly higher animal densities than the environments which evolved together with ruminants, so the pressure is much higher.

Manure that is deposited on pastures by grazing animals is an effective way to preserve and even enhance soil fertility. Many nutrients are recycled in crop cultivation by collecting animal manure from barns and concentrated feeding sites, and controlled composting can make the process even more environmentally friendly. For many areas with high livestock density, manure application substantially replaces the application of synthetic fertilizers on surrounding cropland, which can also help in reducing NO2 emissions. Manure is also spread on forage-producing land that is grazed, rather than cropped.

Manure can also have environmental benefits as a renewable energy source, in digester systems yielding biogas for heating and/or electricity generation. Manure biogas operations can be found in Asia, Europe and North America, and elsewhere. The US EPA estimates that as of July 2010, 157 manure digester systems for bio-gas energy were in operation on commercial-scale US livestock facilities. However, the cost of such systems is high, relative to US energy values, which may be a deterrent for widespread use. Additional factors could be employed to make it more appealing for investors, such as odor control and carbon credits. Manure can be mixed with other organic wastes in anaerobic digesters to take advantage of economies of scale.

Digested waste is more uniform in consistency than untreated organic wastes and can have higher proportions of nutrients that are more available to plants, which enhances the utility of digestate as a fertilizer product. All the previously mentioned options, combined with a reduction in the demand of animal products, could bring agriculture closer to sustainability.

Transport and the environment

Transporting food is a contributor to environmental damage. Food travels over enormous distances due to fluctuations in market prices, with little regard for the environmental costs. It is significantly cheaper to grow bananas or pineapples in developing tropical countries, package and process them overseas in Asia, and then sell them in developed countries such as the UK, than to grow them in the buyer countries, which would require specially designed greenhouses and have higher manpower costs. To lower the footprint of food transport, we should not only look at improving the means of transport themselves, such as electric trucks or more efficient freight ships. Instead, we should encourage communities to aim for food sovereignty, through initiatives like farmer markets, urban gardens and community allotments.

Food waste

While most of the damage done to the environment happens before and while producing the food products, food waste is also a contributing factor. Food rotting in landfills results in CH4, and the nutrients lost by failing to reclaim them drive unsustainable practices such as phosphate mining to produce fertilizers. If a third of all food is wasted, that means that a third of all agricultural emissions are essentially unnecessary. If food waste was a country, it would emit more GHGs than any other except China and the US.

A great shift is needed to reduce food waste, one that goes beyond individual behavior. Reusing surplus food intended for human consumption, such as food donation, is the next best strategy after prevention, followed by animal feed, recycling of nutrients and energy followed by the least preferred option, landfills.

Conclusions

Our current way of producing food damages the environment on multiple scales, both local and global. From polluted ponds where algal blooms wipe out native species to the worldwide changing of the climate, we need to rethink all aspects of our society. Should we be content with being passive consumers, stuck between cheap but environmentally damaging products or their expensive but allegedly more sustainable counterparts, or should we instead try to change the fundamental logic of the system, and seek to become actively involved in the decision-making process which is currently harming all life on earth? 

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