Emissions from agriculture

Agriculture is a major source of greenhouse gas emissions and air pollution. Key pollutants include methane, nitrous oxide, carbon dioxide, and ammonia. However, farmland also has the potential to store carbon and act as a carbon sink.

Methane

In 2019, methane accounted for 18% of global human-caused greenhouse gas emissions (AR6 WGIII), with agriculture responsible for around 40% of these emissions.

The largest sources are ruminant livestock (e.g., cattle, buffalo, sheep, goats, camels) and manure management, contributing 32% of global methane emissions.

Rice cultivation adds another 8%, while agricultural waste burning contributes 1% or less.

Methane is also a key driver of ground-level ozone formation, which harms health and ecosystems.

Nitrous Oxide

Nitrous oxide made up 4% of global greenhouse gas emissions in 2019 (AR6 WGIII), with agriculture responsible for half of these emissions.

The largest share comes from fertilized soils and manure left on pastures.

Carbon Dioxide (CO₂)

Agriculture contributes to CO₂ emissions in two main ways:

Fossil Fuels: Used for machinery, heating buildings, and drying crops.

Land Use and Forestry (LULUCF): Soils and plants store carbon, but changes in land use—especially deforestation—can turn them from a carbon sink into a source. Forests store far more carbon than croplands or pastures.

Ammonia

Agriculture is responsible for 90% of ammonia emissions. Ammonia contributes to:

Nitrogen deposition, leading to eutrophication and acidification of land and water.

Fine particulate matter (PM2.5), a major air pollutant affecting human health.

In regions with high livestock densities, ammonia causes over 50% of nitrogen deposition and PM2.5 exposure.