Livestock emits 6.2 billion tonnes of greenhouse gases a year
Raising the world’s farm animals releases a massive 6.2 billion tonnes of greenhouse gases a year, according to the Food and Agriculture Organization of the United Nations (FAO). That is around 12% of all the greenhouse gases humans emit, and about 40% of the emissions from the entire food system1. It works out to roughly 200 tonnes every second.
The figure is measured in CO2 equivalent: methane, nitrous oxide and carbon dioxide all converted into the amount of CO2 that would warm the planet by the same amount. It covers everything from growing the animals’ feed to their digestion, their manure, and the processing and transport of meat, milk and eggs1.
FAO’s estimate refers to 2015, and there is no newer global figure of the same scope. Since meat and milk production have both grown since then, today’s real number is very likely somewhat higher.
Cattle cause almost two thirds of livestock emissions
Not all farm animals are equal. Cattle, raised for both beef and milk, cause about 3.8 billion tonnes a year, 62% of the livestock total. Pigs cause 14%, chickens 9%, buffalo 8%, and sheep and goats 7%1.
That's the share of livestock's greenhouse gases that comes from cattle raised for beef and milk
By product, meat is responsible for two thirds of livestock emissions, milk for 30% and eggs for the rest1. Per kilogram, beef stands far above everything else: a kilogram of beef from a beef herd comes with around 99 kilograms of greenhouse gases, against about 10 for chicken3. The full picture for beef is on the page for cattle slaughtered for meat.
Methane from the stomach, nitrous oxide from the manure
Livestock emissions come from three different gases, and each has its own source.
The biggest is methane, which makes up slightly more than half of the total1. Cattle, sheep, goats and buffalo are ruminants: animals with a multi-chamber stomach where microbes break down grass. That fermentation produces methane, which the animals mostly burp out. Methane is a much more powerful greenhouse gas than CO2, although it breaks down in the atmosphere within a few decades, which means cutting it has a relatively fast effect on warming.
The second is nitrous oxide, released from manure and from the fertiliser used to grow feed crops. The third is carbon dioxide, from the energy used on farms and in transport, and from clearing forests and grassland to make room for pasture and feed. Around 60% of livestock emissions come directly from the animals and their manure, and 40% from everything else in the supply chain, including feed, fertiliser and land clearing1.
The animals behind most of livestock’s methane.
How livestock emissions could be cut
FAO’s assessment looked at a long list of ways to reduce emissions, and one of the biggest is also one of the least glamorous. Better management of grasslands, the pastures where so many cattle and sheep graze, could on its own cut nearly a third of livestock’s current emissions1.
The other options FAO points to include healthier animals and better breeding, so that each animal produces more meat or milk for the same emissions, reducing food loss and waste, so that fewer animals are needed in the first place, and measures that target the emissions directly1. Eating less beef would cut emissions too, but that depends on what people choose to eat rather than on how animals are farmed.
Where livestock emissions are heading
The direction depends on which forecast you look at. FAO warns that if demand for animal products grows by 20% by 2050, as expected, and nothing else changes, livestock emissions would rise to around 9.1 billion tonnes a year1.
The nearer-term outlook is less steep. The Organisation for Economic Co-operation and Development (OECD) and FAO expect livestock emissions to grow by about 6% over the decade to 2034, only half as fast as meat production, because more of the world’s new meat will come from chicken rather than beef2. That shift lowers the emissions per kilogram, but raises the number of animals slaughtered, as the page on chickens slaughtered for meat shows.
Neither path brings emissions down. Doing that would take the options above working together, and above all it would take the world’s cattle herds, which cause almost two thirds of the problem, to become far less emission-intensive or smaller. For now, livestock looks set to remain one of the large sources of greenhouse gases that is still growing.
The meat these emissions produce, in tonnes.
More on water, land and pollution is on the page for the environmental effects of meat production. The rest of what the world raises and eats is in the food section.
