Livestock farming significantly impacts Earth’s climate. Practices in raising animals for food and other products contribute to atmospheric changes through various agricultural processes.
Direct Greenhouse Gas Contributions
Livestock directly contribute to greenhouse gas emissions through biological processes and manure management. Ruminant animals, such as cattle, sheep, and goats, produce significant amounts of methane (CH4) during their digestive process, known as enteric fermentation. Microbes in their rumens break down plant material, releasing methane as a byproduct expelled primarily through burping. Methane is a potent greenhouse gas, with a global warming potential 27 to 30 times greater than carbon dioxide over a 100-year period, despite its shorter atmospheric lifespan of approximately 12 years.
Manure management also releases methane, especially when stored in liquid systems like lagoons, which create anaerobic conditions. These systems allow organic material to decompose without oxygen, generating methane. In contrast, dry manure systems tend to produce less methane.
Nitrous oxide (N2O) emissions are another concern, primarily originating from manure storage and the application of nitrogen-rich fertilizers used for growing feed crops. Nitrous oxide is formed through microbial processes in the soil, specifically nitrification and denitrification, which convert nitrogen compounds into N2O gas. This gas has an even higher global warming potential than methane, being about 273 times more potent than carbon dioxide over a 100-year timescale. While livestock respiration produces carbon dioxide, this is generally considered part of the natural carbon cycle. However, CO2 emissions linked to livestock farming also arise from energy consumption in farm operations, such as machinery use and transportation, and from the production of feed.
Land Use and Resource Demands
The extensive land and resource requirements of livestock farming create additional climate impacts. Deforestation is a major consequence, particularly in regions like the Amazon, where vast forest areas are cleared to create new pastures for grazing animals or to cultivate feed crops such as soy and corn. This removal of forests releases large quantities of stored carbon into the atmosphere, as trees absorb and store carbon dioxide, and simultaneously reduces the Earth’s natural capacity to remove CO2 from the air.
Overgrazing by livestock can lead to land degradation, contributing to soil erosion and desertification. When soil loses its protective vegetation cover, it becomes more susceptible to wind and water erosion, reducing its ability to sequester carbon. Degraded land also becomes less productive, further stressing the need for more land to support livestock.
Livestock farming also demands substantial water resources. Large volumes of water are necessary for animals to drink, for cleaning farm facilities, and especially for irrigating the vast fields that grow feed crops. This high water usage can strain local water supplies, particularly in regions already facing water scarcity, a problem that can be intensified by changing climate patterns.
Quantifying Livestock’s Climate Footprint
Livestock’s collective impact on global greenhouse gas emissions represents a significant portion of human-caused climate change. The sector is estimated to contribute about 14.5% or more of global anthropogenic greenhouse gas emissions, according to the Food and Agriculture Organization (FAO) of the United Nations. Some analyses suggest this figure could be closer to 16.5% of global emissions.
To put this into perspective, this contribution is comparable to, or even exceeds, the exhaust emissions from all the world’s cars, trucks, planes, and ships combined. Methane accounts for approximately 44% of these emissions, while nitrous oxide makes up about 29%, and carbon dioxide comprises roughly 27%.