Livestock & Emissions

Why livestock matters — and why it’s complicated

Livestock sits at the heart of a difficult tension. Animal-source foods, such as meat, milk, and eggs, support the livelihoods of an estimated one billion people in Africa, Asia, and Latin America, providing essential nutrients, particularly in food-insecure regions. Global demand is also rising rapidly, primarily driven by growing populations and incomes. For example, animal-source foods consumption in lower middle-income countries is projected to increase by 24% by 2034, far above the global average of 6%. Yet meeting this demand carries a high environmental cost. Livestock already uses 77% of agricultural land while providing just 18% of global calories, accounts for roughly 14–20% of global greenhouse gas emissions, and is a leading driver of deforestation — with 41% of tropical forest loss in 2024 linked to cattle pasture expansion. This threatens biodiversity and puts additional stress on already vulnerable ecosystems. The challenge, then, is not simply a matter of increasing production or reducing environmental pressure in isolation, but of navigating both together: expanding food security while meaningfully cutting emissions and halting forest and biodiversity loss.

Most livestock emissions stem from methane (CH4) produced by ruminants during digestion (enteric fermentation) and from manure, together accounting for around 60% of the livestock sector’s GHG footprint. Other sources include carbon dioxide (CO2) from land-use change and nitrous oxide (N2O) from manure and fertilizers. Estimates of livestock’s contribution to global GHG emissions vary: FAO’s 2022 assessment put its share at 12%, while UNEP’s 2023 report suggested it could be as high as 20%. This difference reflects methodology: FAO counts direct emissions only, while broader estimates also include emissions from land-use change and feed crops. Methane is particularly significant: with a Global Warming Potential 81–86 times higher than CO2 over 20 years, it is the sector’s most potent driver of near-term warming. Yet its short atmospheric lifetime also makes it the most actionable lever — reducing methane can act as an “emergency brake” on warming. With livestock emissions still rising at roughly 1% annually, that brake is not yet being applied.

Emission reductions can be evaluated in two ways: absolute emission reductions, which refer to the total decrease in emissions from animal agriculture regardless of output,and relative (or emission intensity) reductions, which reflect decreases in emissions per unit of output (e.g., per kg of meat or litre of milk).

While efficiency gains can reduce emissions intensity, absolute emissions may still rise if production growth outpaces these improvements. In the beef and dairy sector, reductions in emissions intensity have helped avoid substantial emissions, yet total GHG emissions have continued to rise and are projected to increase by a further 6% by 2034. This projected increase is driven by an expected 14% increase in global agricultural production that outpaces efficiency gains.

Measuring methane emissions from livestock presents additional challenges, as no single method is universally accepted. Approaches—ranging from respiration chambers and tracer gas techniques to top‑down atmospheric models and emerging real‑time sensors—differ in accuracy, scalability, and applicability, with performance varying with animal type, feed, and production system. These methodological differences introduce uncertainty into both absolute and intensity estimates, complicating comparisons across systems and regions and influencing how mitigation is reported.