Crops and livestock, and the farmers and pastoralists who nurture them, are heavily influenced by both daily weather patterns and longer climactic trends. However, less apparent is the fact that the agricultural sector is a major contributor of climate change through large greenhouse gas emissions. Agriculture is therefore central to both mitigation of and adaption to climate change.
Scientists say the agriculture sector is responsible for between 10 and 20 percent of the total greenhouse effect caused by human activities.
Greenhouse gas emissions from agriculture arise because of changes in land use (e.g. deforestation), from the use of fossil fuels, and from practices directly from the fields.
Cattle, for instance, are a big source of methane — a powerful greenhouse gas as a byproduct of their digestion. Rice farms are also a source of methane — this time because of bacteria that live in water-logged rice fields.
Greenhouse gas emissions from intensive agriculture systems are particularly high because these systems tend to use large amounts of fossil fuels to power farm equipment, to refrigerate and transport produce over long distances and to produce fertilizer. Synthetic fertilizers also create additional emissions of the powerful greenhouse gas nitrous oxide when they react with the soil. This accounts for about 60 percent of all emissions of nitrous oxide.
Greenhouse gas emissions also increase if land is deforested to make way for agricultural activities, and forest loss also limits the amount of carbon an area of land can absorb from the atmosphere.
Livestock farming is a particularly big contributor to climate change because of the large areas of land that are needed to grow crops to feed the animals.
For all of these reasons and more, agriculture plays a major role in the observed rise in global temperatures that scientists say will have marked impacts on the climate and society worldwide, not least by affecting agriculture itself.
In some areas of the world agriculture is set to benefit from climate change but most regions are projected to suffer. However, there are still very few concrete conclusions about what climate change will mean at the local level.
Climate change is linked with changes to temperature and rainfall patterns which leads to greater extremes and unpredictability in droughts and floods. Additionally, these changing weather conditions affect other species such as pollinators, pests, weeds and parasites.
The main impacts that agriculture could face are changes to temperature and rainfall patterns, with more extremes and a greater risk of droughts and floods that can devastate crops and livestock. Climatic changes can also affect agriculture indirectly by influencing other species such as pollinators, crops pests, weeds and parasites of herd animals.
These changes are projected to hit developing countries hardest, where they could result in rising food prices, reduced food security and an increase in malnutrition.
Agriculture can help to limit the impacts of climate change, both by storing carbon to prevent it from reaching the atmosphere (mitigation) and by enabling farmers to reduce their vulnerability (adaptation).
According to the Intergovernmental Panel on Climate Change, the best ways for the agriculture sector to mitigate climate change include improved management of grazing land, better nutrient use and restoration of organic soils and degraded land.
Combined, these and other approaches could vastly increase the amount of carbon that is stored in the soil of farmland around the world.
The agriculture sector will also need to adapt to reduce the impacts of climate change on food production and livelihoods.
The International Food Policy Research Institute estimated in 2009 that the agriculture sector needs at least US$7 billion per year in additional funding is required to finance the research, rural infrastructure, and irrigation investments needed for adaptation activities to offset the negative effects of climate change on human well-being.
Adaptation will involve farmers changing the varieties of crops they plant, the breeds of livestock they herd, and the way they manage water resources on their farms (see Adaptation to Climate Change).
Most governments have started to examine the impacts of agriculture on climate change and the actions that the sector must take to adapt to its impacts.
Agriculture ministries or departments will be useful sources of information but some of the richest stories will come from farmers themselves.
International agencies that focus on the linkages between climate change and agriculture include the CGIAR centers, which do research on different aspects of agriculture in developing nations (see the CCAFS Agriculture and Food Security and its Commission on Sustainable Agriculture and Climate Change).
As concerns over climate change grow, policy responses can have additional effects on the agriculture sector. For instance, the rise in demand for biofuels can lead to a drop in food production as farmers begin producing biofuel crops instead of food. Also, calls to reduce the distance food travels (food miles) can affect the livelihoods of distant farmers who depend on export markets.
Good sources of news and story ideas include Reuters AlertNet, or the New Agriculturalist.
CASE STUDIES – Adaptation in African Agriculture
Researchers at the Nigeria-based International Institute for Tropical Agriculture (IITA) say the black-eyed pea (or cowpea) is a ‘climate-ready crop’ that could replace climate-vulnerable crops such as rice and maize in parts of Africa.
Like all peas, it is a legume, which means that it has nodules on its roots that contain bacteria that capture nitrogen in the air and convert into a form that the plant can use for growth. This means that farmers who grow the crop would not need to spend money on fertilizers. It also means that the pea is a rich source of protein.
The black-eye pea also grows well in dry conditions, which mean it could be vital for areas affected by drought or unpredictable rainfall. However, the pea is also susceptible to a number of crop pests. Scientists are trying to find new ways to improve the pea’s productivity and are trying to conserve the many varieties of pea that exist in case some have important traits that will prove vital in a climate-constrained world.
For more details and photos, see this Reuters AlertNet story by George Fominyen in Senegal.
National Climate Assessment Agriculture Report
CGIAR – Climate Change, Agriculture and Food Security
CTA Seminar reports on climate change and agriculture
FAO and Climate Change
FAO – Livestock’s Long Shadow [PDF]
IFPRI – Agriculture and Climate Change
IFPRI – Climate change: Impact on agriculture and costs of adaptation
IPCC 4th Assessment Report (2007) – chapter on agriculture and mitigation of climate change [PDF]