Greenhouse gas emissions from agriculture

The amount of greenhouse gas emissions from agriculture is significant: The agriculture, forestry and land use sector contribute between 13% and 21% of global greenhouse gas emissions.^[2] Agriculture contributes towards climate change through direct greenhouse gas emissions and by the conversion of non-agricultural land such as forests into agricultural land.^[3][4] Emissions of nitrous oxide and methane make up over half of total greenhouse gas emission from agriculture.^[5] Animal husbandry is a major source of greenhouse gas emissions.^[6]

The agricultural food system is responsible for a significant amount of greenhouse gas emissions.^[7][8] In addition to being a significant user of land and consumer of fossil fuel, agriculture contributes directly to greenhouse gas emissions through practices such as rice production and the raising of livestock.^[9] The three main causes of the increase in greenhouse gases observed over the past 250 years have been fossil fuels, land use, and agriculture.^[10] Farm animal digestive systems can be put into two categories: monogastric and ruminant. Ruminant cattle for beef and dairy rank high in greenhouse-gas emissions; monogastric, or pigs and poultry-related foods, are low. 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.^[7] Furthermore, CO₂ is actually re-emitted into the atmosphere by plant and soil respiration in the later stages of crop growth, causing more greenhouse gas emissions.^[11] The amount of greenhouse gases produced during the manufacture and use of nitrogen fertilizer is estimated at around 5% of anthropogenic greenhouse gas emissions. The single most important way to cut emissions from it is to use less fertilizers, while increasing the efficiency of their use.^[12]

There are many strategies that can be used to help soften the effects, and the further production of greenhouse gas emissions - this is also referred to as climate-smart agriculture. Some of these strategies include a higher efficiency in livestock farming, which includes management, as well as technology; a more effective process of managing manure; a lower dependence upon fossil-fuels and nonrenewable resources; a variation in the animals' eating and drinking duration, time and location; and a cutback in both the production and consumption of animal-sourced foods.^{[7][13][14][15]} A range of policies may reduce greenhouse gas emissions from the agriculture sector for a more sustainable food system.^{[16]: 816–817}