Food & Climate: The impact of food on the environment

6 minute read

Updated on: 22 Jun 2020

What’s the problem with agriculture?

Humans eat a lot of food. To grow it all, we rely on a process called agriculture, or farming [ref]. Given its scale, it’s no surprise that agriculture is a major contributor to climate change.

Of these emissions, agriculture is responsible for 82% (the orange, green and yellow slices of the pie chart below) [ref1,ref2].

Image of Greenhouse gas emissions from the food supply chain

Greenhouse gas emissions from the food supply chain [ref]

So, where do these emissions come from?

Energy Use

Running a farm requires energy. Most of this energy comes from burning fossil fuels, which releases CO₂ into the atmosphere [ref].

Fertilisers and Pesticides

Many of the chemicals used in agriculture also require a considerable amount of energy to produce [ref1,ref2,ref3].

Farmers often rely on artificial fertilisers [ref1,ref2]: chemicals that contain specific nutrients to help plants grow bigger, stronger, and faster [ref].

Image of Nitrogen is used to make protein

Nitrogen is used to make protein

While fertilisers are extremely useful, their production alone is responsible for 1.2% of global greenhouse gas emissions [ref].

Not only that, most crops can only use around 50% of the fertiliser applied [ref]. Leftover fertilizer is often broken down by soil microbes into nitrous oxide (N₂O) [ref]: a greenhouse gas with a warming effect 300 times stronger than CO₂ [ref].

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 [ref]. This suffocates fish and other aquatic species [ref].

Image of Nitrogen Cycle on the Farm

Nitrogen Cycle on the Farm

Pesticides are another chemical used by farmers. These protect crops from diseases, weeds, and plant-eating insects [ref]. Without crop protection strategies like pesticides, crop losses could be as high as 80% [ref]!

However, like fertilisers, these chemicals require energy to produce [ref]. They are also toxic to many other forms of wildlife [ref], including pollinators that help crop plants reproduce [ref1,ref2], and microbes that keep soils healthy and fertile [ref].

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 [ref].

We’ve already discussed how N₂O can be released from artificial fertilisers. But where else do non-CO₂ emissions come from [ref1,ref2,ref3,ref4,ref5,ref6]? Let’s have a look in the graphic below:

Image of Non-CO₂ emissions in agriculture

Non-CO₂ emissions in agriculture

Deforestation and Soil Degradation

Nearly a quarter of emissions from food production are released when land is cleared for agriculture [ref].

Agriculture uses 50% of Earth’s habitable land [ref] and is responsible for 80% of global deforestation [ref].

Image of Habitable land use

Habitable land use

The crops that replace trees store less carbon and are not as good at holding the soil together [ref]. This makes the soil unstable and results in its degradation, leading to landslides and dust storms [ref1,ref2,ref3].

Image of Soil degradation

Soil degradation

Water use

While water makes up 71% of the Earth’s surface [ref], only 3% of this is freshwater, the water we use to drink, wash, and water crops [ref1,ref2,ref3]. About two thirds of freshwater is locked away in ice, meaning only 1% of global water is accessible for direct use by humans [ref1,ref2,ref3].

Agriculture uses more freshwater than any other industry, accounting for over 70% of global freshwater use [ref1,ref2,ref3].

Let’s look at this in more detail [ref]:

Image of Water Footprints for Different Products

Water Footprints for Different Products

Climate change will only make these problems worse [ref], and by 2025 up to two-thirds of the global population will experience water shortages [ref].

By 2050, the global population is set to reach 9.7 billion [ref], and food production will have to increase by between 50 - 100% to feed our growing population [ref1,ref2,ref3,ref4]. But how can we achieve this when agriculture is already putting such a strain on our resources and our planet?

What is sustainable agriculture?

Let’s recap quickly. Today, agriculture:

  • Releases around 21% of global greenhouse gas emissions [ref1,ref2]
  • Uses lots of energy [ref1,ref2,ref3]
  • Damages surrounding ecosystems [ref1,ref2]
  • Takes up 50% of Earth’s habitable land [ref]
  • Degrades soils, which releases CO₂ and makes it harder for plants to grow [ref1,ref2,ref3]
  • Accounts for 70% of global water use [ref1,ref2,ref3]

If agriculture was made more sustainable, food could be produced on the same land indefinitely, without depleting resources [ref1,ref2,ref3]. Sustainable farming is also less vulnerable to environmental change, which will be essential if we are to continue to feed ourselves in the face of climate change [ref1,ref2].

In the next chapters, we will look at what farmers and consumers can do to make food production more sustainable.

Next chapter!