14.5% of all human-caused greenhouse gas emissions are attributable to livestock farming, an industry that emits not only carbon dioxide (CO2), but also methane (CH4) and nitrous oxide (N2O) two gases considered to play a similar role to CO2 in driving global warming. Though methane and nitrous oxide do not remain in the atmosphere as long as CO2, their respective climate warming potential is about 25 times and 300 times higher than that of carbon dioxide.
Most emissions in livestock farming result from feed production (58%) and are released during animals' digestive processes (31%); ruminants such as cattle, sheep and goats produce large quantities of methane. Processing and transport account for sizable share of greenhouse gas emissions (7%), as well, as does the storage of manure (4%).
About 87% of methane and nitrous oxide emissions in livestock farming are attributable to cattle farming because of the sheer number of animals.
A 2021 study published in Nature Food found that that plant-based foods account for just 29% of greenhouse gasses emitted by the global food industry. In contrast, 57% of greenhouse gas emission in the industry are linked to breeding and rearing cows, pigs and other livestock, as well as producing feed.
A quarter of global greenhouse gas emissions in the food industry are said to result from beef production alone. 99.48 kilograms of carbon dioxide equivalents per kilogram, beef production remains the biggest source of greenhouse gases. This is almost double the carbon dioxide equivalents per kilogram linked to lamb and mutton production (39.72 kilograms). Pork and poultry production show lower carbon dioxide equivalents, at 12.31 kilograms and 9.87 per kilogram of meat, respectively. Both also emit fewer emissions than cheese production (23.88 kilograms) and fish farming (13.63 kilograms).
Most greenhouse gas emissions from plant-based foods are lower than those linked to animal-based foods. Take the example of rice. Producing one kilogram of the food staple results in 4.45 kilograms of carbon dioxide equivalents — less than half the emissions released when producing one kilogram of poultry.
Beef, lamb and mutton industries require 116 times the land needed to cultivate rice. Animal farming accounts for 78% of agricultural land worldwide. Yet expanding agricultural and pastureland leads to habitat destruction.