Glaciers are melting, sea levels are rising and bush fires are blazing around the globe.

These events are happening because of global warming. By releasing heat-trapping gases called greenhouse gases, temperatures are rising. These gases let in light but prevent heat from escaping, like the glass walls of a greenhouse.

There are different gases that get released into the atmosphere and contribute to global warming. Greenhouse gases are emitted into the atmosphere in a range of ways, including through burning fossil fuels, producing cement and steel, farming soils and cattle, clearing forests, as well as through rice fields and landfill.

Heat-trapping greenhouse gases are produced in six sectors:

Food systems account for approximately 26–34% of global greenhouse gas emissions (Poore & Nemecek, 2018; Crippa et al., 2021; IPCC AR6, 2022). There are four categories to consider when looking at agriculture emissions:

• Livestock & fisheries (31% of emissions)
• Crop production (27% of emissions)
• Land use (24% of emissions)
• Supply chains (18% of emissions)

Livestock & fisheries

Emissions in that category are produced from animals raised for meat, dairy and eggs, 31% of emissions are only caused during the on-farm ‘production’. They exclude land use, the supply chain processes and crop production for animal feed. 

Crop production

21% of food’s emissions are attributed to the crop production for direct human consumption, and 6% to the production of animal feed. Those emissions come from fertilizers (nitrous oxide), manure and methane for rice production. As well as CO2  from machinery. 

Land use

The majority of emissions in this category are from land use for livestock (16%). 8% are attributed to crops for human consumption. 

Supply chains

This category includes food processing, transport, packaging and retail, which require energy and resource inputs. Whilst supply chain emissions seem to be high, a lot of it is due to high food waste. Food waste emissions are substantial: one-quarter of emissions (3.3 billion tonnes of CO2eq) from food production ends up as wastage either from supply chain losses or consumers.