Humans eat a lot of food. To grow it all, we rely on a process called agriculture, or farming. Given its scale, it’s no surprise that agriculture is a major contributor to climate change.
Of these emissions from the food supply chain, agriculture is responsible for 82% (the orange, green and yellow slices of the pie chart below)
So, where do these emissions come from?
1) Energy Use
Running a farm requires energy. Most of this energy comes from burning fossil fuels, which releases CO₂ into the atmosphere.
2) Fertilisers and Pesticides
Many of the chemicals used in agriculture also require a considerable amount of energy to produce.Farmers often rely on artificial fertilisers: chemicals that contain specific nutrients to help plants grow bigger, stronger, and faster.
While fertilisers are extremely useful, their production alone is responsible for 1.2% of global greenhouse gas emissions. Not only that, most crops can only use around 50% of the fertiliser applied. Leftover fertilizer is often broken down by soil microbes into nitrous oxide (N₂O): a greenhouse gas with a warming effect 300 times stronger than CO₂. If fertiliser is swept into rivers and lakes, the nutrients inside it feed algae and plankton that reduce the amount of light and oxygen in the water. This suffocates fish and other aquatic species.
Pesticides are another chemical used by farmers. These protect crops from diseases, weeds, and plant-eating insects. Without crop protection strategies like pesticides, crop losses could be as high as 80%.
However, like fertilisers, these chemicals require energy to produce. They are also toxic to many other forms of wildlife, including pollinators that help crop plants reproduce, and microbes that keep soils healthy and fertile.
3) Non-CO₂ Emissions
Agriculture is the biggest emitter of the greenhouse gases nitrous oxide (N₂O) and methane (CH₄), accounting for 80% and 45% of the man-made emissions of these gases respectively.
Non CO₂ Emissions in Agriculture
4) Deforestation and Soil Degradation
Nearly a quarter of emissions from food production are released when land is cleared for agriculture. Agriculture uses 50% of Earth’s habitable land and is responsible for 80% of global deforestation. When land is cleared for agriculture, a significant amount of stored carbon from the wood & roots of trees as well as disturbed soil is released into the atmosphere. The crops that replace trees store less carbon and are not as good at holding the soil together. This makes the soil unstable and results in its degradation, leading to landslides and dust storms.
5) Water use
While water makes up 71% of the Earth’s surface, only 3% of this is freshwater, the water we use to drink, wash, and water crops. About two thirds of freshwater is locked away in ice, meaning only 1% of global water is accessible for direct use by humans.
Agriculture uses more freshwater than any other industry, accounting for over 70% of global freshwater use.
Climate change will only make these problems worse, and by 2025 up to two-thirds of the global population will experience water shortages.
By 2050, the global population is set to reach 9.7 billion, and food production will have to increase by between 50 - 100% to feed our growing population.