Greenhouse gas emissions from agriculture
Greenhouse gas emissions from agriculture arise mainly from biological processes in livestock digestion, soil nitrogen cycling, and rice cultivation, releasing methane through enteric fermentation and manure decomposition, nitrous oxide via denitrification and nitrification in fertilized fields, and carbon dioxide from fuel combustion and organic matter oxidation in soils.[1][2] These emissions totaled approximately 16.2 billion tonnes of CO₂-equivalent in global agrifood systems in 2022, encompassing direct farm-level outputs and related activities.[3] Direct emissions from agricultural production account for about 10 to 12 percent of total anthropogenic greenhouse gases, with methane comprising roughly half of the sector's contribution due to ruminant animals producing around 120 million tonnes annually and rice systems adding 20 to 40 million tonnes depending on cultivation practices and estimates.[4][5][6] Nitrous oxide, with its high global warming potential, originates predominantly from synthetic fertilizer application and manure, driving nearly three-quarters of human-induced increases over recent decades and representing 70 percent of agricultural N₂O from fertilizers alone.[7][8] Broader assessments including land-use changes for agricultural expansion elevate the sector's share to 21 to 30 percent of global emissions, though distinctions between direct emissions and deforestation-related CO₂ fluxes remain subjects of methodological debate in inventories.[9][10] Key challenges involve balancing emission reductions—such as through improved feed efficiency or precision fertilization—against imperatives for global food production amid population growth, with empirical data underscoring livestock and fertilizer use as primary levers for mitigation without relying on unproven large-scale shifts in dietary patterns.[11][12]Contextual Importance
Contribution to global food security and economic output
Agriculture provides essential food supplies that underpin global food security, supporting the nutrition needs of approximately 8 billion people as of 2023, with staple crops and livestock products forming the basis of diets worldwide.[13] In regions prone to undernourishment, such as sub-Saharan Africa where over 20% of the population faces hunger, agricultural output directly mitigates famine risks by enabling local production and resilience against supply disruptions.[14] Growth in agricultural productivity has historically reduced poverty at twice the rate of non-agricultural sectors, as increased yields lower food prices and enhance access for low-income households.[15] Economically, the sector generated a value added of USD 4.0 trillion in 2023, representing about 4% of global gross domestic product (GDP).[16] [17] This output sustains supply chains for food processing, trade, and related industries, with projections indicating a 14% rise in gross agricultural production value to USD 3.96 trillion (in constant terms) by 2034, driven by productivity gains rather than land expansion.[18] In developing economies, agriculture's GDP share often exceeds 10-15%, serving as a primary engine for rural development and export revenues, such as in coffee, cocoa, and grain-producing nations.[19] Employment in agriculture accounts for roughly 26% of the global workforce, or about 1 billion people, with concentrations in low- and middle-income countries where it exceeds 50% of jobs in many cases.[20] [21] This labor-intensive activity supports livelihoods for 80% of the world's poor in rural areas, where farming provides both income and subsistence, thereby stabilizing economies vulnerable to urban migration or commodity shocks.[22] Sustaining these contributions requires balancing output expansion with resource efficiency, as disruptions to agricultural viability could exacerbate food insecurity and economic instability in dependent regions.[23]Relative share compared to other emission sectors
Agriculture contributes approximately 10–12% of global anthropogenic greenhouse gas emissions through direct processes such as enteric fermentation in livestock, manure management, rice cultivation, and synthetic fertilizer application, predominantly in the form of methane and nitrous oxide.[9][4] These emissions totaled around 9–10 GtCO₂-equivalent annually in the 2010s, compared to total global emissions of 59 GtCO₂-eq in 2019.[24] In contrast, the energy sector—including fossil fuel combustion for electricity generation, heating, transportation, and manufacturing—accounts for the majority at 73–75%, while industrial processes (e.g., cement and chemical production) contribute 5–6%, and waste 3%.[9][25] When incorporating land-use change and forestry emissions linked to agricultural expansion (collectively under AFOLU), the sector's net share rises to 21% of global emissions, averaging 11.9 GtCO₂-eq per year from 2010–2019; this reflects gross agricultural emissions offset partially by carbon sinks in unmanaged lands, though deforestation for cropland and pastures drives net positives in many regions.[9] Agriculture proper dominates AFOLU contributions, with non-CO₂ gases comprising over 70% of agricultural emissions, underscoring their potency despite lower volumes relative to CO₂-heavy energy sources.[9] Broader assessments of agrifood systems—which extend to processing, packaging, transportation, and retail but exclude consumer waste—estimate a 31–34% global share, reaching 16.2 GtCO₂-eq in 2022; this includes on-farm activities (45% of the total) and post-production stages (55%), highlighting supply chain extensions beyond strict agricultural boundaries.[26][27] Such figures from FAO integrate modeled data with uncertainties from varying methodologies, contrasting narrower sectoral breakdowns that prioritize territorial emissions.| Sector | Approximate Global Share (%) | Primary Gases | Key Sources |
|---|---|---|---|
| Energy (incl. transport, buildings) | 73–75 | CO₂ dominant | Fossil fuel combustion[9] |
| Agriculture (direct) | 10–12 | CH₄, N₂O | Livestock, soils, rice[9] |
| AFOLU (incl. land change) | 21 | CO₂, CH₄, N₂O | Deforestation, ag processes[9] |
| Industry (processes) | 5–6 | CO₂, others | Cement, metals[25] |
| Waste | 3 | CH₄ | Landfills, wastewater[9] |
Estimation and Trends
Current global and regional estimates
Global greenhouse gas emissions from agricultural activities, including enteric fermentation in livestock, manure management, rice cultivation, synthetic fertilizer application, and crop residue burning, totaled approximately 10.84 Gt CO₂eq in 2022, according to an analysis of Food and Agriculture Organization (FAO) data.[28] This figure excludes emissions from land-use change and forestry, focusing on direct on-farm processes. Relative to total anthropogenic GHG emissions excluding land use, land-use change, and forestry (LULUCF)—estimated at 53.0 Gt CO₂eq for 2023—these agricultural emissions comprised roughly 20%.[29] [28] Regionally, emissions are disproportionately concentrated in Asia, which accounts for over half of global agricultural GHG output, driven by extensive rice paddies emitting methane and large ruminant herds producing enteric fermentation methane. Eastern Asia, led by China, and Southern Asia, dominated by India, together contribute the largest shares due to population-driven demand for staples like rice and dairy.[26] In 2020 FAO data, agrifood system emissions (encompassing farm-gate agriculture) in Asia reached about 9 Gt CO₂eq, compared to 2.5 Gt in the Americas and 2 Gt in Africa.[26] Among individual countries, China emitted the highest agricultural GHGs in recent years, followed by India, the United States, Brazil, and Indonesia, collectively representing over 50% of the global total as of 2019 FAO estimates, with similar patterns persisting into the 2020s.[30] [31] In per capita terms, emissions vary widely; for instance, major livestock producers like Australia and New Zealand exceed 10 t CO₂eq per person annually from agriculture, while densely populated Asian nations average under 1 t.[10] These disparities reflect differences in production intensity, dietary patterns, and agricultural practices, with developing regions showing higher aggregate emissions from low-efficiency systems.[26]| Region/Country Group | Approximate Share of Global Agricultural GHG Emissions (ca. 2020-2022) | Key Drivers |
|---|---|---|
| Asia | >50% | Rice, livestock |
| Americas | ~20% | Beef, soy |
| Africa | ~10% | Subsistence livestock |
| Europe & N. America | ~15% | Dairy, intensive crops |
| China (top country) | ~15-20% | All sources |
| India (2nd) | ~10-15% | Rice, dairy |