View source for Greenhouse gas emissions from agriculture

{{short description|none}}
{{See  also|Effects of climate change on agriculture}}
[[File:Global greenhouse gas emissions from food production.png|thumb|One quarter of the world's greenhouse gas emissions result from food and agriculture (data from 2019).]]
The amount of '''greenhouse gas emissions from agriculture''' is significant: The agriculture, forestry and land use sectors contribute between 13% and 21% of global [[greenhouse gas emissions]]. Emissions come from ''direct'' greenhouse gas emissions (for example from [[Rice|rice production]] and [[livestock]] farming). And from ''indirect'' emissions. With regards to direct emissions, [[nitrous oxide]] and [[methane]] makeup over half of total greenhouse gas emissions from agriculture.
A 2023 review emphasizes that emissions from agricultural soils are shaped by factors such as soil type, climate, and management practices. It also highlights several mitigation strategies, including conservation tillage, precision agriculture, improved water use, and the application of biochar, that can reduce emissions and enhance soil carbon storage. Indirect emissions on the other hand come from the conversion of non-agricultural land such as [[forest]]s into agricultural land. Furthermore, there is also [[fossil fuel]] consumption for transport and [[fertilizer]] production. For example, the [[Haber process|manufacture]] and use of [[nitrogen fertilizer]] contributes around 5% of all global greenhouse gas emissions. [[Environmental impacts of animal agriculture|Livestock farming]] is a major source of greenhouse gas emissions. At the same time, [[Effects of climate change on livestock|livestock farming is affected by climate change]]. 

Farm animals' digestive systems can be put into two categories: [[monogastric]] and [[ruminant]]. Ruminant cattle for beef and dairy rank high in greenhouse gas emissions. In comparison, monogastric, or pigs and poultry-related foods, are lower. The consumption of the monogastric types may yield less emissions. Monogastric animals have a higher feed-conversion efficiency and also do not produce as much methane. Non-ruminant livestock, such as poultry, emit far fewer greenhouse gases.

There are many strategies to reduce greenhouse gas emissions from agriculture (this is one of the goals of [[climate-smart agriculture]]). Mitigation measures in the food system can be divided into four categories. These are demand-side changes, ecosystem protections, mitigation on farms, and mitigation in [[supply chains]]. On the demand side, limiting [[food waste]] is an effective way to reduce food emissions. Changes to a diet less reliant on animal products such as [[plant-based diets]] are also effective. This could include [[Milk substitute|milk substitutes]] and [[Meat alternative|meat alternatives]]. Several methods are also under investigation to reduce the greenhouse gas emissions from livestock farming. These include genetic selection, introduction of [[Methanotroph|methanotrophic bacteria]] into the rumen, diet modification and grazing management.

== Global estimates ==
[[File:World Farm-gate Greenhouse Gas Emissions By Activity.svg|thumb|World farm-gate greenhouse gas emissions by activity]]Total emissions from agrifood systems in 2022 amounted to 16.2 billion tonnes of [[carbon dioxide]] equivalent (Gt CO2eq) of GHG released into the atmosphere, an increase of 10%, or 1.5 Gt CO2eq compared with 2000.

In 2020, it was estimated that the [[food system]] as a whole contributed 37% of total greenhouse gas emissions and that this figure was on course to increase by 30–40% by 2050 due to population growth and dietary change.

Between 2010 and 2019, agriculture, forestry and land use contributed between 13% and 21% to global greenhouse gas emissions. [[Nitrous oxide]] and [[methane]] make up over half of total greenhouse gas emissions from agriculture.

=== Older estimates ===
In 2010, agriculture, [[forestry]] and [[land-use change]] were estimated to contribute 20–25% of global annual emissions.

== Emissions by type of activity ==
{{See also|Environmental impact of agriculture}}
=== Land use changes ===
[[File:2019 Greenhouse gas emissions per capita by region - variwide bar chart - IPCC AR6 WG3 - Fig SPM.2c.svg|thumb|upright=1.5 | Substantial land-use change contributions to emissions have been made by Latin America, Southeast Asia, Africa, and Pacific Islands. The area of rectangles shows the region's total emissions in 2019.]]Agriculture contributes to greenhouse gas increases through land use in four main ways:
* CO<sub>2</sub> releases linked to [[deforestation]]
* Methane releases from [[rice|rice cultivation]]
* Methane releases from [[enteric fermentation]] in cattle
* [[Nitrous oxide]] releases from [[fertilizer]] application

Together, these agricultural processes comprise 54% of [[methane emissions]], roughly 80% of nitrous oxide emissions, and virtually all carbon dioxide emissions tied to land use.

[[Land cover]] has changed majorly since 1750, as humans have [[deforestation|deforested]] [[temperate region]]s. When forests and woodlands are cleared to make room for fields and [[pasture]]s, the [[albedo]] of the affected area increases, which can result in either warming or cooling effects depending on local conditions. Deforestation also affects regional [[RuBisCO|carbon reuptake]], which can result in increased concentrations of [[carbon dioxide|CO<sub>2</sub>]], the dominant greenhouse gas. Land-clearing methods such as [[slash and burn]] compound these effects, as the burning of [[biomatter]] directly releases greenhouse gases and particulate matter such as [[soot]] into the air. Land clearing can destroy the [[soil carbon sponge]].

=== Livestock ===
{{See also|Environmental impacts of animal agriculture}}
[[File:Livestock near Walnut Farm - geograph.org.uk - 3240836.jpg|thumb|Livestock farms where methane is emitted from the cattle.]]
[[File:World Emissions Intensity Of Agricultural Commodities (2021).svg|thumb|Meat from cattle and sheep have the highest emissions intensity of any agricultural commodity.]]
[[File:Environmental-impact-of-food-by-life-cycle-stage.png|thumb|upright=1.4|[[Greenhouse gas emissions]] across the [[supply chain]] for different foods]]

Livestock produces the majority of greenhouse gas emissions from agriculture and demands around 30% of agricultural [[fresh water|freshwater]] needs, while only supplying 18% of the global [[calorie]] intake. Animal-derived food plays a larger role in meeting human [[protein]] needs, yet is still a minority of supply at 39%, with crops providing the rest.

Out of the [[Shared Socioeconomic Pathways]] used by the [[Intergovernmental Panel on Climate Change]], only SSP1 offers any realistic possibility of meeting the {{convert|1.5|C-change|F-change}} target. Together with measures like a massive deployment of [[green technology]], this pathway assumes animal-derived food will play a lower role in global diets relative to now. As a result, there have been calls for phasing out [[subsidies]] currently offered to livestock farmers in many places worldwide, and [[net zero]] transition plans now involve limits on total livestock headcounts, including substantial reductions of existing stocks in some countries with extensive animal agriculture sectors like Ireland. Yet, an outright end to human consumption of meat and/or animal products is not currently considered a realistic goal.Therefore, any comprehensive plan of [[Climate change adaptation|adaptation]] to the [[effects of climate change]], particularly the present and future [[effects of climate change on agriculture]], must also consider livestock.

Livestock activities also contribute disproportionately to land-use effects, since crops such as [[Maize|corn]] and [[alfalfa]] are cultivated to feed the animals.

In 2010, [[enteric fermentation]] accounted for 43% of the total greenhouse gas emissions from all agricultural activity in the world. The meat from ruminants has a higher carbon equivalent footprint than other meats or vegetarian sources of protein based on a global meta-analysis of lifecycle assessment studies. Small ruminants such as sheep and goats contribute approximately 475 million tons of carbon dioxide equivalent to GHG emissions, which constitutes around 6.5% of world agriculture sector emissions. Methane production by animals, principally ruminants, makes up an estimated 15-20% of global production of methane.

Worldwide, livestock production occupies 70% of all land used for agriculture or 30% of the land surface of the Earth. The global [[food system]] is responsible for one-third of the global anthropogenic [[Greenhouse gas emissions|GHG emissions]], of which meat accounts for nearly 60%.

Cows, sheep and other [[Ruminant|ruminants]] digest their food by [[enteric fermentation]], and their [[Burping|burps]] are the main [[methane emissions]] from [[land use, land-use change, and forestry]]: together with methane and [[nitrous oxide]] from [[manure]], this makes livestock the main source of greenhouse gas emissions from agriculture. In addition, manure left on pasture, applied to soil, and treated in management systems together contribute to 7%–10% of global agricultural greenhouse gas emissions. 

The [[IPCC Sixth Assessment Report]] in 2022 stated that: "Diets high in plant protein and low in meat and dairy are associated with lower GHG emissions. [...] Where appropriate, a shift to [[Plant-based diet|diets with a higher share of plant protein]], moderate intake of animal-source foods and reduced intake of [[Saturated fat|saturated fats]] could lead to substantial decreases in GHG emissions. Benefits would also include reduced land occupation and nutrient losses to the surrounding environment, while at the same time providing health benefits and reducing mortality from diet-related non-communicable diseases."|label6=[[Poultry]]|label13=[[Legumes]]|data12=1.2|label12=[[Maize]]|data11=1.2|label11=[[Wheat]]|data10=1.7|label10=[[List of root vegetables|Starchy Roots]]|data9=6.8|label9=[[Egg as food|Eggs]]|data8=8.6|label8=[[Fishery|Non-trawling Fishery]]|data7=9.1|label7=[[Dairy]]|data6=10|data5=10|float=right|label5=[[Pork]]|data4=12|label4=[[Aquaculture|Non-recirculating Aquaculture]]|data3=26|label3=[[Trawling|Trawling Fishery]]|data2=30|label2=[[Recirculating aquaculture system|Recirculating Aquaculture]]|data1=62|label1=[[Ruminant|Ruminant Meat]]|data_max=62|width_units=em|bar_width=20|data_type=Greenhouse Gas Emissions<br>(g CO<small>2</small>-C<small>eq</small> per g protein)|label_type=Food Types|data13=0.25}}According to a 2022 study quickly stopping animal agriculture would provide half the GHG emission reduction needed to meet the [[Paris Agreement]] goal of limiting global warming to 2&nbsp;°C. There are calls to phase out livestock subsidies as part of a [[just transition]].

In the context of global GHG emissions, food production within the global food system accounts for approximately 26%. Breaking it down, livestock and fisheries contribute 31%, whereas crop production, land use, and supply chains add 27%, 24%, and 18% respectively to the emissions.

A 2023 study found that a [[vegan]] diet reduced emissions by 75%.

Research in New Zealand estimated that switching agricultural production towards a healthier diet while reducing greenhouse gas emissions would cost approximately 1% of the agricultural sector's export revenue for New Zealand, which is an order of magnitude less than the estimated health system savings from a healthier diet.

Research continues on the use of various seaweed species, in particular [[Asparagopsis armata|Asparegopsis armata]], as a food additive that helps reduce methane production in ruminants.

=== Fertilizer ===
{{Excerpt|Fertilizer|Contribution to climate change|file=no}}

=== Crop management ===


==== Rice production ====
[[File:NP_Rice_Emissions18_(5687953086).jpg|right|thumb|Research work by the [[International Center for Tropical Agriculture]] to measure the greenhouse gas emissions of rice production.]]
{{excerpt|Rice#Greenhouse gases from rice production|file=no}}

== Emissions by type of greenhouse gas ==
Agricultural activities emit the [[greenhouse gas]]es [[carbon dioxide]], [[methane]] and [[nitrous oxide]].

=== Carbon dioxide emissions ===
Activities such as [[Tillage|tilling]] of fields, planting of crops, and shipment of products cause carbon dioxide emissions. Agriculture-related emissions of carbon dioxide account for around 11% of global greenhouse gas emissions. Farm practices such as reducing tillage, decreasing empty land, returning [[biomass]] residue of crops to the soil, and increasing the use of cover crops can reduce carbon emissions.

=== Methane emissions ===
[[File:Methane-emissions-agriculture (OWID 0666).png|thumb|Methane emissions from agriculture, 2019. Methane (CHa) emissions are measured in tonnes of carbon dioxide-equivalents]]
[[File:The Global Methane Budget 2008–2017.png|thumb|Global methane budget.]][[Methane emissions]] from livestock are the number one contributor to agricultural greenhouse gases globally. Livestock are responsible for 14.5% of total anthropogenic greenhouse gas emissions. One cow alone will emit 220 pounds of methane per year. While the [[residence time]] of methane is much shorter than that of carbon dioxide, it is 28 times more capable of trapping heat. Not only do livestock contribute to harmful emissions, but they also require a lot of land and may [[Overgrazing|overgraze]], which leads to unhealthy soil quality and reduced species diversity. A few ways to reduce methane emissions include switching to plant-rich diets with less meat, feeding the cattle more nutritious food, [[manure management]], and [[compost]]ing.

Traditional [[Rice|rice cultivation]] is the second biggest agricultural methane source after [[livestock]], with a near-term warming impact equivalent to the [[Climate change and aviation|carbon dioxide emissions from all aviation]]. Government involvement in agricultural policy is limited due to the high demand for agricultural products like corn, wheat, and milk. The United States Agency for International Development's (USAID) global hunger and food security initiative, the Feed the Future project, is addressing food loss and waste. By addressing food loss and waste, greenhouse gas emission mitigation is also addressed. By only focusing on dairy systems of 20 value chains in 12 countries, food loss and waste could be reduced by 4-10%. These numbers are impactful and would mitigate greenhouse gas emissions while still feeding the population.

=== Nitrous oxide emissions ===
[[File:Global Nitrous Oxide Budget 2020.png|thumb|Global nitrous oxide budget.]]Nitrous oxide emission comes from the increased use of synthetic and organic fertilizers. [[Fertilizer]]s increase crop yield production and allow the crops to grow at a faster rate. Agricultural emissions of nitrous oxide make up 6% of the United States' greenhouse gas emissions; they have increased in concentration by 30% since 1980. While 6% may appear to be a small contribution, nitrous oxide is 300 times more effective at trapping heat per pound than carbon dioxide and has a residence time of around 120 years. Different management practices such as conserving water through [[drip irrigation]], monitoring soil nutrients to avoid overfertilization, and using [[cover crop]]s in place of fertilizer application may help in reducing nitrous oxide emissions.

== Reducing emissions ==
{{Further|Climate change mitigation|Climate-smart agriculture}}
Agriculture is often not included in government emissions reduction plans. For example, the agricultural sector is exempt from the [[European Union Emission Trading Scheme|EU emissions trading scheme]] which covers around 40% of the EU greenhouse gas emissions.

{{excerpt|Climate change mitigation#Agriculture, forestry and land use|file=no}}

== See also ==
{{Portal|Climate change|Environment|Energy}}
* [[Agroecology]]
* [[Effects of climate change on agriculture]]
* [[Effects of climate change on livestock]]
* [[Environmental issues with agriculture]]

== External links ==
* [http://www.fao.org/climatechange/en/ Climate change] on the [[Food and Agriculture Organization]] of the United Nations website.
* [http://www.ifpri.org/publication/climate-change-1 Report on the relationship between climate change, agriculture and food security] by the [[International Food Policy Research Institute]]
* [http://www.adb.org/features/12-things-know-2012-rice Climate Change, Rice and Asian Agriculture: 12 Things to Know] Asian Development Bank

{{Climate change}}
{{agriculture footer}}

[[Category:Climate change and agriculture| ]]
[[Category:Greenhouse gas emissions]]
{{二次利用|date=12 July 2025, at 03:13}}