Food Production's Dark Side: A Pollution Story

Food production is a major contributor to pollution, with one-quarter of the world's greenhouse gas emissions resulting from agriculture and food production. This includes emissions from the production of fertilisers and pesticides, food processing, transport, packaging, and retail. In addition, agriculture is responsible for 70% of global freshwater withdrawals and 78% of global ocean and freshwater eutrophication, the pollution of waterways with nutrient-rich water. Air pollution stunts the growth of staple crops such as wheat, rice, and maize, reducing their nutritional value and yield. Nitrogen oxides, emitted from car exhaust and industrial emissions, are among the most widely emitted pollutants, directly damaging crop cells and reducing crop yields. Climate change caused by pollution also impacts food production, with rising temperatures, changing weather patterns, natural disasters, and heat events reducing crop yields.

Air pollution stunts crop growth

Nitrogen oxides, or NOx, are widely emitted pollutants that can directly damage crop cells and contribute to the formation of ozone, which is known to reduce crop yields. A Stanford University-led study found that reducing NOx emissions can lead to dramatic gains in crop yields, with potential improvements of nearly 10% for winter and summer crops in Western Europe and 6-8% for crops in India.

Black carbon emissions can be reduced by addressing sources such as household cooking, lighting, and heating, as well as heavy-duty engines in trucks, buses, and ships. Similarly, reducing methane emissions, a key ingredient in the formation of tropospheric ozone, can halve global crop losses from these pollutants by 2050, saving billions of dollars and improving food security.

The effects of air pollution on crop growth are particularly detrimental in countries with high levels of hunger and vulnerability to climate change. These countries often have a low capacity to adapt, and small changes in crop growth can have immediate and devastating consequences. Therefore, addressing air pollution and climate change is critical to ensuring food security and preserving the livelihoods of millions.

In addition to the direct impacts on crop growth, air pollution also affects biodiversity, weather patterns, and natural disasters, all of which have indirect effects on agricultural productivity. With food demand projected to increase sharply by 2050, urgent action is needed to mitigate the impacts of air pollution and climate change on our global food systems.

Agriculture uses 70% of global freshwater withdrawals

Agriculture is responsible for 70% of global freshwater withdrawals, according to the Food and Agriculture Organization of the United Nations. This figure varies by country, with large variations seen across different geographical regions and income levels. For instance, low-income countries tend to have a much higher average agricultural water use than high-income countries. South Asia, Africa, and Latin America have some of the highest water withdrawal rates for agriculture, with several countries in these regions using over 80% of their water for this purpose. In contrast, countries in Europe, such as Germany and the Netherlands, use less than 1% of their water for agriculture.

The high water usage in agriculture is largely due to irrigation, which has been a crucial factor in increasing crop yields worldwide. However, this has also led to water stress in some regions. Water stress is categorized by the percentage of withdrawals in relation to resources: less than 25% is no stress, 25-50% is low stress, 50-75% is medium stress, 75-100% is high stress, and over 100% is critical stress. Many countries in the Middle East and North Africa fall into the critical stress category, extracting water at unsustainable rates from existing sources or relying heavily on desalinization.

The issue of water stress is expected to worsen with future demands, requiring a reallocation of water from lower to higher productivity sectors. Agriculture, due to its high water consumption, will likely be a significant source of water reallocation. This shift in water usage will need to occur both physically and virtually, with water-intensive food production moving from water-abundant to water-scarce regions.

To address water stress and improve water security, investments in sustainable intensification of agriculture and irrigation infrastructure are crucial. For example, the World Bank has supported projects such as the Gambia Commercial Agriculture and Value Chain Management Project, which assists female farmers in the Gambia with solar-powered water pumps and drip irrigation systems, modernizing vegetable gardening practices and improving livelihoods. These types of initiatives can help balance water usage and ensure sustainable agricultural practices.

Meat and dairy emit more greenhouse gases than plant-based foods

The production of meat and dairy is a significant contributor to greenhouse gas emissions. Animal-based food production is responsible for nearly 60% of all greenhouse gas emissions from food production, with meat and dairy products accounting for 57% of total food emissions. This is largely due to the large amounts of land required to graze animals and grow their feed, which is often cleared through the felling of forests, releasing stored carbon dioxide.

Cows, sheep, and goats are ruminants, meaning they emit large amounts of methane when digesting food. Livestock manure and the use of nitrogen fertilisers during the production of animal feed also cause nitrous oxide emissions, another potent greenhouse gas. The majority of the world's cropland is used to feed livestock rather than people, and livestock also produce large quantities of methane. This combination of factors results in very high emissions from animal-based food production.

In contrast, plant-based foods generally use less energy, land, and water and have lower greenhouse gas intensities. Shifting towards plant-rich diets can lead to a significant reduction in greenhouse gas emissions compared to current dietary patterns in most industrialised countries. This does not need to compromise protein and micronutriutrient intake, as plant-based sources such as beans, chickpeas, lentils, nuts, and grains can provide these.

However, it is important to note that some plant-based foods, such as rice, can also be polluting. Rice is mostly grown in flooded fields, creating ideal conditions for methane-emitting bacteria. Nevertheless, the lowest-carbon animal products still have a higher carbon footprint than most plant-based foods.

Overall, reducing the consumption of meat and dairy in favour of plant-based alternatives is a key way to lower the environmental impact of the food system.

Shipping food emits carbon

The combustion of heavy fuel oil (HFO) and other petroleum-based fuels, such as coal, crude oil, diesel, and natural gas, is the primary source of emissions from ships. This combustion releases harmful gases, including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), which contribute to climate change. Additionally, ships produce sulfur oxide (SOx) emissions, which pose significant environmental and health risks.

The distance food travels, or "food miles," is a critical factor in determining its carbon footprint. The more miles a food item travels, the less sustainable it becomes. High-income regions, including North America, Europe, and Oceania, have per-capita food miles and emissions almost three times that of other regions. This is largely driven by the dietary habits of high-income countries, such as purchasing non-seasonal produce, which requires international transportation.

However, it is important to note that shipping food by boat is generally more carbon-efficient than other transportation methods, such as air transport. For example, shipping one kilogram of avocados from Mexico to the United Kingdom generates 0.21 kg of CO2 emissions, which is only around 8% of the total carbon footprint of avocados. Nevertheless, the emissions associated with global food miles are higher than previously believed, and transport accounts for nearly 20% of all emissions related to the food creation chain.

To reduce the carbon emissions associated with shipping food, consumers can buy local produce, especially for highly perishable foods like seafood, berries, and certain vegetables, which are often transported by plane over long distances. Slowing the speed of ships can also reduce emissions, as it results in burning less fuel and emitting less CO2 and other greenhouse gases.

Agriculture deteriorates air quality

Secondly, the production and use of artificial fertilizers contribute significantly to air pollution. The production of fertilizers has skyrocketed from 20 million tons in 1950 to nearly 190 million tons today, with about a third of them being nitrogen-based. While fertilizers help increase crop yields, excess fertilizers wash off fields each year, polluting watersheds and contributing to eutrophication, or the pollution of waterways with nutrient-rich water. Eutrophication can lead to the creation of oxygenless "dead zones" in rivers and oceans, causing harm to aquatic ecosystems.

Thirdly, the use of pesticides and herbicides in agriculture can also lead to air pollution. Pesticide "drift" occurs when pesticides sprayed on fields reach nearby lands or neighbourhoods, contributing to poor air quality in those areas. This can have detrimental effects on both human health and the environment, as evidenced by the decline in populations of insects like the monarch butterfly and native bees, which has been partially attributed to the use of pesticides.

Finally, agriculture contributes to air pollution through methane emissions, particularly from livestock manure and the use of fossil fuels in the production of fertilizers and pesticides. Methane is a potent greenhouse gas that contributes to global warming and climate change. According to the United Nations Environment Programme (UNEP), ground-level ozone pollution, which includes methane, will reduce staple crop yields by 26% by 2030.

It is important to note that the relationship between agriculture and air pollution is bidirectional, meaning that air pollution can also negatively impact agriculture. For example, air pollution can stunt crop growth and reduce the nutritional value of certain foods, exacerbating the challenge of ensuring food security for a growing global population. Therefore, addressing agriculturally-caused air pollution is crucial not only for improving air quality but also for safeguarding food production and supply.

Frequently asked questions