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] Emissions come from direct greenhouse gas emissions (for example from rice production and livestock farming).[3] and from indirect emissions. With regards to direct emissions, nitrous oxide and methane make up over half of total greenhouse gas emission from agriculture.[4] Indirect emissions on the other hand come from the conversion of non-agricultural land such as forests into agricultural land.[5][6] Furthermore, there is also fossil fuel consumption for transport and fertilizer production. For example, the manufacture and use of nitrogen fertilizer contributes around 5% of all global greenhouse gas emissions.[7] Livestock farming is a major source of greenhouse gas emissions.[8] At the same time, livestock farming is affected by climate change.
See also: Effects of climate change on agriculture
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.[9] Non-ruminant livestock, such as poultry, emit far fewer greenhouse gases.[10]
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.[11]: XXV This could include milk substitutes and meat alternatives. Several methods are also under investigation to reduce the greenhouse gas emissions from livestock farming. These include genetic selection,[12][13] introduction of methanotrophic bacteria into the rumen,[14][15] vaccines, feeds,[16] diet modification and grazing management.[17][18][19]