Greenhouse gas emissions from agriculture/ja: Difference between revisions

<div lang="en" dir="ltr" class="mw-content-ltr">

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."{{Bar chart|title=Mean greenhouse gas emissions for different food types|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.

<div lang="en" dir="ltr" class="mw-content-ltr">

=== Fertilizer ===

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

<div lang="en" dir="ltr" class="mw-content-ltr">

=== Crop management ===

<div lang="en" dir="ltr" class="mw-content-ltr">

==== 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.

<div lang="en" dir="ltr" class="mw-content-ltr">

=== 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.

<div lang="en" dir="ltr" class="mw-content-ltr">

=== 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.