Climate change and agriculture

Climate change and agriculture

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Encyclopedia
Climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

 and agriculture
are interrelated processes, both of which take place on a global scale. Global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...

 is projected to have significant impacts on conditions affecting agriculture, including temperature, carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

, glacial run-off, precipitation
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...

 and the interaction of these elements. These conditions determine the carrying capacity
Carrying capacity
The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment...

 of the biosphere
Biosphere
The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, a closed and self-regulating system...

 to produce enough food for the human population and domesticated animals. The overall effect of climate change on agriculture will depend on the balance of these effects. Assessment of the effects of global climate changes on agriculture might help to properly anticipate and adapt farming to maximize agricultural production
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

.

At the same time, agriculture has been shown to produce significant effects on climate change, primarily through the production and release of greenhouse gases such as carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

, methane
Methane
Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

, and nitrous oxide
Nitrous oxide
Nitrous oxide, commonly known as laughing gas or sweet air, is a chemical compound with the formula . It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...

, but also by altering the Earth's land cover
Land Cover
Land cover is the physical material at the surface of the earth. Land covers include grass, asphalt, trees, bare ground, water, etc. There are two primary methods for capturing information on land cover: field survey and analysis of remotely sensed imagery....

, which can change its ability to absorb or reflect heat and light, thus contributing to radiative forcing
Radiative forcing
In climate science, radiative forcing is generally defined as the change in net irradiance between different layers of the atmosphere. Typically, radiative forcing is quantified at the tropopause in units of watts per square meter. A positive forcing tends to warm the system, while a negative...

. Land use
Land use
Land use is the human use of land. Land use involves the management and modification of natural environment or wilderness into built environment such as fields, pastures, and settlements. It has also been defined as "the arrangements, activities and inputs people undertake in a certain land cover...

 change such as deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....

 and desertification
Desertification
Desertification is the degradation of land in drylands. Caused by a variety of factors, such as climate change and human activities, desertification is one of the most significant global environmental problems.-Definitions:...

, together with use of fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

s, are the major anthropogenic sources of carbon dioxide; agriculture itself is the major contributor to increasing methane and nitrous oxide concentrations in Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

's atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

.

Impact of climate change on agriculture



Despite technological advances, such as improved varieties, genetically modified organisms
GMO
A GMO is a genetically modified organism.GMO may also refer to:* Gell-Mann–Okubo mass formula in particle physics* General Medical Officer, a designation for United States Army soldiers* Generalised molecular orbital theory, in chemistry...

, and irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

 systems, weather is still a key factor in agricultural productivity, as well as soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

 properties and natural communities
Biota (ecology)
Biota are the total collection of organisms of a geographic region or a time period, from local geographic scales and instantaneous temporal scales all the way up to whole-planet and whole-timescale spatiotemporal scales. The biota of the Earth lives in the biosphere.-See...

. The effect of climate on agriculture is related to variabilities in local climates rather than in global climate patterns. The Earth's average surface temperature has increased by 1.5°F {0.83°C} since 1880. Consequently, agronomist
Agronomist
An agronomist is a scientist who specializes in agronomy, which is the science of utilizing plants for food, fuel, feed, and fiber. An agronomist is an expert in agricultural and allied sciences, with the exception veterinary sciences.Agronomists deal with interactions between plants, soils, and...

s consider any assessment has to be individually consider each local area
Ecoregion
An ecoregion , sometimes called a bioregion, is an ecologically and geographically defined area that is smaller than an ecozone and larger than an ecosystem. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural...

.

On the other hand, agricultural trade
Agricultural economics
Agricultural economics originally applied the principles of economics to the production of crops and livestock — a discipline known as agronomics. Agronomics was a branch of economics that specifically dealt with land usage. It focused on maximizing the crop yield while maintaining a good soil...

 has grown in recent years, and now provides significant amounts of food, on a national level to major importing countries, as well as comfortable income
Gross domestic product
Gross domestic product refers to the market value of all final goods and services produced within a country in a given period. GDP per capita is often considered an indicator of a country's standard of living....

 to exporting ones. The international aspect of trade and security in terms of food implies the need to also consider the effects of climate change on a global scale.

A study published in Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....

suggests that, due to climate change, "southern Africa could lose more than 30% of its main crop, maize, by 2030. In South Asia losses of many regional staples, such as rice, millet and maize could top 10%".

The Intergovernmental Panel on Climate Change
Intergovernmental Panel on Climate Change
The Intergovernmental Panel on Climate Change is a scientific intergovernmental body which provides comprehensive assessments of current scientific, technical and socio-economic information worldwide about the risk of climate change caused by human activity, its potential environmental and...

 (IPCC) has produced several reports that have assessed the scientific literature
Scientific literature
Scientific literature comprises scientific publications that report original empirical and theoretical work in the natural and social sciences, and within a scientific field is often abbreviated as the literature. Academic publishing is the process of placing the results of one's research into the...

 on climate change. The IPCC Third Assessment Report
IPCC Third Assessment Report
The IPCC Third Assessment Report, Climate Change 2001, is an assessment of available scientific and socio-economic information on climate change by the IPCC. The IPCC was established in 1988 by the United Nations Environment Programme and the UN's World Meteorological Organization ".....

, published in 2001, concluded that the poorest countries would be hardest hit, with reductions in crop yields in most tropical and sub-tropical regions due to decreased water availability, and new or changed insect pest incidence. In Africa and Latin America many rainfed crops are near their maximum temperature tolerance, so that yields are likely to fall sharply for even small climate changes; falls in agricultural productivity of up to 30% over the 21st century are projected. Marine life and the fishing industry will also be severely affected in some places.

Climate change induced by increasing greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

es is likely to affect crops differently from region to region. For example, average crop yield is expected to drop down to 50% in Pakistan according to the UKMO
Met Office
The Met Office , is the United Kingdom's national weather service, and a trading fund of the Department for Business, Innovation and Skills...

 scenario whereas corn production in Europe is expected to grow up to 25% in optimum hydrologic conditions.

More favourable effects on yield tend to depend to a large extent on realization of the potentially beneficial effects of carbon dioxide on crop growth and increase of efficiency in water use. Decrease in potential yields is likely to be caused by shortening of the growing period, decrease in water availability and poor vernalization
Vernalization
Vernalization is the acquisition of a plant's ability to flower or germinate in the spring by exposure to the prolonged cold of winter...

.

In the long run, the climatic change could affect agriculture in several ways :
  • productivity, in terms of quantity
    Quantity
    Quantity is a property that can exist as a magnitude or multitude. Quantities can be compared in terms of "more" or "less" or "equal", or by assigning a numerical value in terms of a unit of measurement. Quantity is among the basic classes of things along with quality, substance, change, and relation...

     and quality of crops
  • agricultural practices, through changes of water use (irrigation) and agricultural inputs such as herbicide
    Herbicide
    Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...

    s, insecticide
    Insecticide
    An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...

    s and fertilizer
    Fertilizer
    Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

    s
  • environmental effects, in particular in relation of frequency and intensity of soil drainage
    Drainage
    Drainage is the natural or artificial removal of surface and sub-surface water from an area. Many agricultural soils need drainage to improve production or to manage water supplies.-Early history:...

     (leading to nitrogen leaching), soil erosion, reduction of crop diversity
    Biodiversity
    Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

  • rural space, through the loss and gain of cultivated lands, land speculation
    Speculation
    In finance, speculation is a financial action that does not promise safety of the initial investment along with the return on the principal sum...

    , land renunciation, and hydraulic amenities.
  • adaptation, organisms may become more or less competitive, as well as humans may develop urgency to develop more competitive organisms, such as flood resistant or salt resistant varieties of rice.


They are large uncertainties to uncover, particularly because there is lack of information on many specific local regions, and include the uncertainties on magnitude of climate change, the effects of technological changes on productivity, global food demands, and the numerous possibilities of adaptation.

Most agronomists believe that agricultural production will be mostly affected by the severity and pace of climate change, not so much by gradual trends in climate. If change is gradual, there may be enough time for biota
Biota (ecology)
Biota are the total collection of organisms of a geographic region or a time period, from local geographic scales and instantaneous temporal scales all the way up to whole-planet and whole-timescale spatiotemporal scales. The biota of the Earth lives in the biosphere.-See...

 adjustment. Rapid climate change, however, could harm agriculture in many countries, especially those that are already suffering from rather poor soil and climate conditions, because there is less time for optimum natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....

 and adaption.

Observed impacts


So far, the effects of regional climate change on agriculture have been relatively limited. Changes in crop phenology
Phenology
Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate...

 provide important evidence of the response to recent regional climate change. Phenology is the study of natural phenomena that recur periodically, and how these phenomena relate to climate and seasonal changes. A significant advance in phenology has been observed for agriculture and forestry in large parts of the Northern Hemisphere.

Projections


As part of the IPCC's Fourth Assessment Report
IPCC Fourth Assessment Report
Climate Change 2007, the Fourth Assessment Report of the United Nations Intergovernmental Panel on Climate Change , is the fourth in a series of reports intended to assess scientific, technical and socio-economic information concerning climate change, its potential effects, and options for...

, Schneider et al. (2007) projected the potential future effects of climate change on agriculture. With low to medium confidence, they concluded that for about a 1 to 3 °C global mean temperature increase (by 2100, relative to the 1990–2000 average level) there would be productivity decreases for some cereals in low latitudes, and productivity increases in high latitudes. In the IPCC Fourth Assessment Report, "low confidence" means that a particular finding has about a 2 out of 10 chance of being correct, based on expert judgement. "Medium confidence" has about a 5 out of 10 chance of being correct. Over the same time period, with medium confidence, global production potential was projected to:
  • increase up to around 3 °C,
  • very likely decrease above about 3 °C.


Most of the studies on global agriculture assessed by Schneider et al. (2007) had not incorporated a number of critical factors, including changes in extreme events, or the spread of pests and diseases. Studies had also not considered the development of specific practices or technologies to aid adaptation.

Food security


Climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

 merely increases the urgency of reforming trade policies to ensure that global food security
Food security
Food security refers to the availability of food and one's access to it. A household is considered food-secure when its occupants do not live in hunger or fear of starvation. According to the World Resources Institute, global per capita food production has been increasing substantially for the past...

 needs are met” said C. Bellmann, ICTSD Programmes Director. A new ICTSD-IPC study by Jodie Keane suggests that climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

 could cause farm output in sub-Saharan Africa
Sub-Saharan Africa
Sub-Saharan Africa as a geographical term refers to the area of the African continent which lies south of the Sahara. A political definition of Sub-Saharan Africa, instead, covers all African countries which are fully or partially located south of the Sahara...

 to decrease by 12 percent by 2080 - although in some African countries this figure could be as much as 60 percent, with agricultural exports declining by up to one fifth in others. Adapting to climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

 could cost the agriculture sector $14bn globally a year, the study finds.

The IPCC Fourth Assessment Report also describes the impact of climate change on food security
Food security
Food security refers to the availability of food and one's access to it. A household is considered food-secure when its occupants do not live in hunger or fear of starvation. According to the World Resources Institute, global per capita food production has been increasing substantially for the past...

. Easterling et al. (2007) looked at studies that made quantitative projections of climate change impacts on food security. It was noted that these projections were highly uncertain and had limitations. However, the assessed studies suggested a number of fairly robust findings. The first was that climate change would likely increase the number of people at risk of hunger
Hunger
Hunger is the most commonly used term to describe the social condition of people who frequently experience the physical sensation of desiring food.-Malnutrition, famine, starvation:...

 compared with reference scenario
Climate change scenario
This article is about climate change scenarios. Socioeconomic scenarios are used by analysts to make projections of future greenhouse gas emissions and to assess future vulnerability to climate change...

s with no climate change. Projected climate change impacts depended strongly on future social
Social change
Social change refers to an alteration in the social order of a society. It may refer to the notion of social progress or sociocultural evolution, the philosophical idea that society moves forward by dialectical or evolutionary means. It may refer to a paradigmatic change in the socio-economic...

 and economic development
Economic development
Economic development generally refers to the sustained, concerted actions of policymakers and communities that promote the standard of living and economic health of a specific area...

. Additionally, the magnitude of climate change impacts was projected to be smaller compared to the impact of social and economic development. In 2006, the global estimate for the number of people undernourished
Malnutrition
Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....

 was 820 million. Under the SRES A1, B1, and B2 scenarios (see the SRES article for information on each scenario group), projections for the year 2080 showed a reduction in the number of people undernourished of about 560–700 million people, with a global total of undernourished people of 100–240 million in 2080. By contrast, the SRES A2 scenario showed only a small decrease in the risk of hunger from the 2006 level. The smaller reduction under A2 was attributed to the higher projected future population level in this scenario.

Easterling et al. (2007) concluded that sub-Saharan Africa
Sub-Saharan Africa
Sub-Saharan Africa as a geographical term refers to the area of the African continent which lies south of the Sahara. A political definition of Sub-Saharan Africa, instead, covers all African countries which are fully or partially located south of the Sahara...

 would likely surpass Asia as the most food-insecure region. This projection was largely independent of climate change and mostly the result of projected social and economic development. Easterling et al. (2007) pointed to the large potential benefits of climate change mitigation (i.e., reducing greenhouse gas emissions) on the agriculture sector. Easterling et al. (2007) suggested that these benefits might only become apparent in the second half of the 21st century.

Regional

  • Africa:
    • Africa's geography makes it particularly vulnerable to climate change, and seventy per cent of the population rely on rain-fed agriculture for their livelihoods. Tanzania
      Tanzania
      The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...

      's official report on climate change suggests that the areas that usually get two rainfalls in the year will probably get more, and those that get only one rainy season will get far less. The net result is expected to be that 33% less maize—the country's staple crop—will be grown. Alongside other factors, regional climate change – in particular, reduced precipitation – is thought to have contributed to the conflict in Darfur
      War in Darfur
      The Darfur Conflict was a guerrilla conflict or civil war centered on the Darfur region of Sudan. It began in February 2003 when the Sudan Liberation Movement/Army and Justice and Equality Movement groups in Darfur took up arms, accusing the Sudanese government of oppressing non-Arab Sudanese in...

      . The combination of decades of drought, desertification
      Desertification
      Desertification is the degradation of land in drylands. Caused by a variety of factors, such as climate change and human activities, desertification is one of the most significant global environmental problems.-Definitions:...

       and overpopulation
      Overpopulation
      Overpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. The term often refers to the relationship between the human population and its environment, the Earth...

       are among the causes of the conflict, because the Baggara Arab nomad
      Nomad
      Nomadic people , commonly known as itinerants in modern-day contexts, are communities of people who move from one place to another, rather than settling permanently in one location. There are an estimated 30-40 million nomads in the world. Many cultures have traditionally been nomadic, but...

      s searching for water have to take their livestock further south, to land mainly occupied by farming peoples.
    • With high confidence, IPCC (2007:13) concluded that climate variability and change would severely compromise agricultural production and access to food.
  • Asia: With medium confidence, IPCC (2007:13) projected that by the mid-21st century, in East
    East Asia
    East Asia or Eastern Asia is a subregion of Asia that can be defined in either geographical or cultural terms...

     and Southeast Asia, crop yields could increase up to 20%, while in Central
    Central Asia
    Central Asia is a core region of the Asian continent from the Caspian Sea in the west, China in the east, Afghanistan in the south, and Russia in the north...

     and South Asia, yields could decrease by up to 30%. Taken together, the risk of hunger was projected to remain very high in several developing countries. More detailed analysis of rice yields by the International Rice Research Institute
    International Rice Research Institute
    The International Rice Research Institute is an international NGO. Its headquarters are in Los Baños, Laguna, Philippines, and it has offices in sixteen countries...

     forecast 20% reduction in yields over the region per degree Celsius of temperature rise. Rice becomes sterile if exposed to temperatures above 35 degrees for more than one hour during flowering and consequently produces no grain.
  • Australia and New Zealand: Hennessy et al.. (2007:509) assessed the literature for this region. They concluded that without further adaptation to climate change, projected impacts would likely be substantial: By 2030, production from agriculture and forestry was projected to decline over much of southern and eastern Australia, and over parts of eastern New Zealand; In New Zealand, initial benefits were projected close to major rivers and in western and southern areas. Hennessy et al.. (2007:509) placed high confidence in these projections.
  • Europe: With high confidence, IPCC (2007:14) projected that in Southern Europe, climate change would reduce crop productivity. In Central and Eastern Europe, forest productivity was expected to decline. In Northern Europe, the initial effect of climate change was projected to increase crop yields.
  • Latin America: With high confidence, IPCC (2007:14) projected that in drier areas of Latin America, productivity of some important crops would decrease and livestock productivity decline, with adverse consequences for food security. In temperate zones, soybean
    Soybean
    The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses...

     yields were projected to increase.
  • North America:
    • According to a paper by Deschenes and Greenstone (2006), predicted increases in temperature and precipitation will have virtually no effect on the most important crops in the US.
    • With high confidence, IPCC (2007:14–15) projected that over the first few decades of this century, moderate climate change would increase aggregate yields of rain-fed agriculture by 5–20%, but with important variability among regions. Major challenges were projected for crops that are near the warm end of their suitable range or which depend on highly utilized water resources.

  • Polar regions (Arctic and Antarctic):
    • For the Guardian newspaper, Brown (2005) reported on how climate change had affected agriculture in Iceland. Rising temperatures had made the widespread sowing of barley
      Barley
      Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, as a base malt for beer and certain distilled beverages, and as a component of various health foods...

       possible, which had been untenable twenty years ago. Some of the warming was due to a local (possibly temporary) effect via ocean currents from the Caribbean, which had also affected fish stocks.
    • Anisimov et al.. (2007:655) assessed the literature for this region. With medium confidence, they concluded that the benefits of a less severe climate were dependent on local conditions. One of these benefits was judged to be increased agricultural and forestry opportunities.
  • Small islands: In a literature assessment, Mimura et al.. (2007:689) concluded, with high confidence, that subsistence
    Subsistence agriculture
    Subsistence agriculture is self-sufficiency farming in which the farmers focus on growing enough food to feed their families. The typical subsistence farm has a range of crops and animals needed by the family to eat and clothe themselves during the year. Planting decisions are made with an eye...

     and commercial agriculture
    Commercial agriculture
    Commercial Agriculture refers to a process of large-scale production of crops for sale, intended for widespread distribution to wholesalers or retail outlets. In commercial farming crops such as wheat, maize, tea, coffee, sugarcane, cashew, rubber, banana, cotton are harvested and sold into world...

     would very likely be adversely affected by climate change.

Shortage in grain production


Between 1996 and 2003, grain
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...

 production
Production, costs, and pricing
The following outline is provided as an overview of and topical guide to industrial organization:Industrial organization – describes the behavior of firms in the marketplace with regard to production, pricing, employment and other decisions...

 has stabilized slightly over 1800 millions of ton
Ton
The ton is a unit of measure. It has a long history and has acquired a number of meanings and uses over the years. It is used principally as a unit of weight, and as a unit of volume. It can also be used as a measure of energy, for truck classification, or as a colloquial term.It is derived from...

s. In 2000, 2001, 2002 and 2003, grain stocks have been dropping, resulting in a global grain harvest
Harvest
Harvest is the process of gathering mature crops from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper...

 that was short of consumption
Consumption (economics)
Consumption is a common concept in economics, and gives rise to derived concepts such as consumer debt. Generally, consumption is defined in part by comparison to production. But the precise definition can vary because different schools of economists define production quite differently...

 by 93 millions of tons in 2003.

The Earth's average temperature has been rising since the late 1970s, with nine of the 10 warmest years on record occurring since 1995. In 2002, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 and the United States suffered sharp harvest reductions because of record temperatures and drought. In 2003 Europe suffered very low rainfall throughout spring and summer, and a record level of heat damaged most crops
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

 from the United Kingdom and France in the Western Europe through Ukraine
Ukraine
Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...

 in the East
Eastern Europe
Eastern Europe is the eastern part of Europe. The term has widely disparate geopolitical, geographical, cultural and socioeconomic readings, which makes it highly context-dependent and even volatile, and there are "almost as many definitions of Eastern Europe as there are scholars of the region"...

. Bread price
Price
-Definition:In ordinary usage, price is the quantity of payment or compensation given by one party to another in return for goods or services.In modern economies, prices are generally expressed in units of some form of currency...

s have been rising in several countries in the region. (see fr:canicule 2003).

Poverty impacts


Researchers at the Overseas Development Institute
Overseas Development Institute
The Overseas Development Institute is one of the leading independent think tanks on international development and humanitarian issues. Based in London, its mission is "to inspire and inform policy and practice which lead to the reduction of poverty, the alleviation of suffering and the achievement...

 (ODI) have investigated the potential impacts climate change could have on agriculture, and how this would affect attempts at alleviating poverty in the developing world. They argued that the effects from moderate climate change are likely to be mixed for developing countries. However, the vulnerability of the poor in developing countries to short term impacts from climate change, notably the increased frequency and severity of adverse weather events is likely to have a negative impact. This, they say, should be taken into account when defining agricultural policy
Agricultural policy
Agricultural policy describes a set of laws relating to domestic agriculture and imports of foreign agricultural products. Governments usually implement agricultural policies with the goal of achieving a specific outcome in the domestic agricultural product markets...

.

Mitigation and Adaptation in Developing Countries


The Intergovernmental Panel on Climate Change (IPCC
IPCC
IPCC may refer to:*Intergovernmental Panel on Climate Change, of the United Nations*Independent Police Complaints Commission, of England and Wales*Irish Peatland Conservation Council...

) has reported that agriculture is responsible for over a quarter of total global greenhouse gas emissions. Given that agriculture’s share in global gross domestic product (GDP) is about 4 percent, these figures suggest that agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

 is highly Green House Gas intensive. Innovative agricultural practices and technologies can play a role in climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...

 mitigation and adaptation. This adaptation and mitigation potential is nowhere more pronounced than in developing countries where agricultural productivity remains low; poverty, vulnerability and food insecurity remain high; and the direct effects of climate change are expected to be especially harsh. Creating the necessary agricultural technologies and harnessing them to enable developing countries to adapt their agricultural systems to changing climate will require innovations in policy and institutions as well. In this context, institutions and policies are important at multiple scales.

Travis Lybbert and Daniel Sumner suggest six policy principles:
(1) The best policy and institutional responses will enhance information flows, incentives and flexibility.
(2) Policies and institutions that promote economic development and reduce poverty will often improve agricultural adaptation and may also pave the way for more effective climate change mitigation through agriculture.
(3) Business as usual among the world’s poor is not adequate.
(4) Existing technology options must be made more available and accessible without overlooking complementary capacity and investments.
(5) Adaptation and mitigation in agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

 will require local responses, but effective policy responses must also reflect global impacts and inter-linkages.
(6) Trade
Trade
Trade is the transfer of ownership of goods and services from one person or entity to another. Trade is sometimes loosely called commerce or financial transaction or barter. A network that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and...

 will play a critical role in both mitigation and adaptation, but will itself be shaped importantly by climate change.

Crop development models


Models for climate behavior are frequently inconclusive. In order to further study effects of global warming on agriculture, other types of models, such as crop development models, yield prediction, quantities of water or fertilizer consumed, can be used. Such models condense the knowledge accumulated of the climate, soil, and effects observed of the results of various agricultural practices. They thus could make it possible to test strategies of adaptation to modifications of the environment.

Because these models are necessarily simplifying natural conditions (often based on the assumption that weeds, disease and insect pest
Pest (animal)
A pest is an animal which is detrimental to humans or human concerns. It is a loosely defined term, often overlapping with the related terms vermin, weeds, parasites and pathogens...

s are controlled), it is not clear whether the results they give will have an in-field reality. However, some results are partly validated with an increasing number of experimental results.

Other models, such as insect and disease development models based on climate projections are also used (for example simulation of aphid
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...

 reproduction or septoria
Septoria
Septoria are Ascomycete fungi that causes numerous leaf spot diseases on field crops, forages and many vegetables, and is responsible for yield losses...

 (cereal fungal disease) development).

Scenarios are used in order to estimate climate changes effects on crop development and yield. Each scenario is defined as a set of meteorological variables, based on generally accepted projections. For example, many models are running simulations based on doubled carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 projections, temperatures raise ranging from 1 °C up to 5 °C, and with rainfall levels an increase or decrease of 20%. Other parameters may include humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...

, wind, and solar activity. Scenarios of crop models are testing farm-level adaptation, such as sowing date shift, climate adapted species (vernalisation need, heat and cold resistance), irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

 and fertilizer adaptation, resistance to disease. Most developed models are about wheat, maize, rice and soybean
Soybean
The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses...

.

Temperature potential effect on growing period


Duration of crop growth
Cell growth
The term cell growth is used in the contexts of cell development and cell division . When used in the context of cell division, it refers to growth of cell populations, where one cell grows and divides to produce two "daughter cells"...

 cycle
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...

s are above all, related to temperature. An increase in temperature will speed up development. In the case of an annual crop, the duration between sowing
Sowing
Sowing is the process of planting seeds.-Plants which are usually sown:Among the major field crops, oats, wheat, and rye are sowed, grasses and legumes are seeded, and maize and soybeans are planted...

 and harvesting will shorten (for example, the duration in order to harvest corn could shorten between one and four weeks). The shortening of such a cycle could have an adverse effect on productivity because senescence
Senescence
Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...

 would occur sooner.

Effect of elevated carbon dioxide on crops


Carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 is essential to plant growth. Rising CO2 concentration in the atmosphere can have both positive and negative consequences.

Increased CO2 is expected to have positive physiological effects by increasing the rate of photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...

. Currently, the amount of carbon dioxide in the atmosphere is 380 parts per million. In comparison, the amount of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 is 210,000 ppm. This means that often plants may be starved of carbon dioxide, due to the enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 that fixes , rubisco
RuBisCO
Ribulose-1,5-bisphosphate carboxylase oxygenase, commonly known by the shorter name RuBisCO, is an enzyme involved in the first major step of carbon fixation, a process by which atmospheric carbon dioxide is converted by plants to energy-rich molecules such as glucose. RuBisCo is an abbreviation...

 also fixes oxygen in the process of photorespiration
Photorespiration
Photorespiration, or "'photo-respiration'", is a process in plant metabolism by which RuBP has oxygen added to it by the enzyme , instead of carbon dioxide during normal photosynthesis. This is the beginning step of the Calvin-Benson cycle...

. The effects of an increase in carbon dioxide would be higher on C3 crops (such as wheat) than on C4 crops (such as maize), because the former is more susceptible to carbon dioxide shortage. Studies have shown that increased CO2 leads to fewer stomata developing on plants which leads to reduced water usage. Under optimum conditions of temperature and humidity, the yield increase could reach 36%, if the levels of carbon dioxide are doubled.

Further, few studies have looked at the impact of elevated carbon dioxide concentrations on whole farming systems. Most models study the relationship between CO2 and productivity in isolation from other factors associated with climate change, such as an increased frequency of extreme weather events
Extreme weather
Extreme weather includes weather phenomena that are at the extremes of the historical distribution, especially severe or unseasonal weather. The most commonly used definition of extreme weather is based on an event's climatological distribution. Extreme weather occurs only 5% or less of the time...

, seasonal shifts, and so on.

In 2005, the Royal Society in London concluded that the purported benefits of elevated carbon dioxide concentrations are “likely to be far lower than previously estimated” when factors such as increasing ground-level ozone
Tropospheric ozone
Ozone is a constituent of the troposphere . Photochemical and chemical reactions involving it drive many of the chemical processes that occur in the atmosphere by day and by night...

 are taken into account."

Effect on quality


According to the IPCC's TAR, "The importance of climate change impacts on grain and forage quality emerges from new research. For rice, the amylose content of the grain—a major determinant of cooking quality—is increased under elevated CO2" (Conroy et al., 1994). Cooked rice grain from plants grown in high- environments would be firmer than that from today's plants. However, concentrations of iron and zinc, which are important for human nutrition, would be lower (Seneweera and Conroy, 1997). Moreover, the protein content of the grain decreases under combined increases of temperature and CO2 (Ziska et al., 1997)." Studies using FACE
Free-Air Concentration Enrichment
Free-Air Carbon dioxide Enrichment is a method used by ecologists and plant biologists that raises the concentration of in a specified area and allows the response of plant growth to be measured...

 have shown that increases in CO2 lead to decreased concentrations of micronutrients in crop plants. This may have knock-on effects on other parts of ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

s as herbivores will need to eat more food to gain the same amount of protein.

Studies have shown that higher CO2 levels lead to reduced plant uptake of nitrogen (and a smaller number showing the same for trace elements such as zinc) resulting in crops with lower nutritional value. This would primarily impact on populations in poorer countries less able to compensate by eating more food, more varied diets, or possibly taking supplements.

Reduced nitrogen content in grazing plants has also been shown to reduce animal productivity in sheep, which depend on microbes in their gut to digest plants, which in turn depend on nitrogen intake.

Agricultural surfaces and climate changes


Climate change may increase the amount of arable land
Arable land
In geography and agriculture, arable land is land that can be used for growing crops. It includes all land under temporary crops , temporary meadows for mowing or pasture, land under market and kitchen gardens and land temporarily fallow...

 in high-latitude region by reduction of the amount of frozen lands. A 2005 study reports that temperature in Siberia has increased three degree Celsius in average since 1960 (much more than the rest of the world). However, reports about the impact of global warming on Russian agriculture indicate conflicting probable effects : while they expect a northward extension of farmable lands, they also warn of possible productivity losses and increased risk of drought.

Sea levels are expected to get up to one meter higher by 2100, though this projection is disputed. A rise in the sea level would result in an agricultural land loss, in particular in areas such as South East Asia. Erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

, submergence of shorelines, salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

 of the water table
Water table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...

 due to the increased sea levels, could mainly affect agriculture through inundation of low-lying lands
Depression (geology)
A depression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms.Structural or tectonic related:...

.

Low lying areas such as Bangladesh, India and Vietnam will experience major loss of rice crop if sea levels are expected to rise by the end of the century. Vietnam for example relies heavily on its southern tip, where the Mekong Delta lies, for rice planting. Any rise in sea level of no more than a meter will drown several km2. of rice paddies, rendering Vietnam incapable of producing its main staple and export of rice.

Erosion and fertility


The warmer atmospheric temperatures observed over the past decades are expected to lead to a more vigorous hydrological cycle, including more extreme rainfall events. Erosion and soil degradation
Soils retrogression and degradation
Soil retrogression and degradation are two regressive evolution processes associated with the loss of equilibrium of a stable soil. Retrogression is primarily due to erosion and corresponds to a phenomenon where succession reverts back to pioneer conditions . Degradation is an evolution,...

 is more likely to occur. Soil fertility
Fertility
Fertility is the natural capability of producing offsprings. As a measure, "fertility rate" is the number of children born per couple, person or population. Fertility differs from fecundity, which is defined as the potential for reproduction...

 would also be affected by global warming. However, because the ratio of carbon to nitrogen is a constant
Constant (mathematics)
In mathematics, a constant is a non-varying value, i.e. completely fixed or fixed in the context of use. The term usually occurs in opposition to variable In mathematics, a constant is a non-varying value, i.e. completely fixed or fixed in the context of use. The term usually occurs in opposition...

, a doubling of carbon is likely to imply a higher storage of nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

 in soils as nitrate
Nitrate
The nitrate ion is a polyatomic ion with the molecular formula NO and a molecular mass of 62.0049 g/mol. It is the conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically-bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a...

s, thus providing higher fertilizing elements for plants, providing better yields. The average needs for nitrogen could decrease, and give the opportunity of changing often costly fertilisation
Fertilisation
Fertilisation is the fusion of gametes to produce a new organism. In animals, the process involves the fusion of an ovum with a sperm, which eventually leads to the development of an embryo...

 strategies.

Due to the extremes of climate that would result, the increase in precipitations would probably result in greater risks of erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

, whilst at the same time providing soil with better hydration, according to the intensity of the rain. The possible evolution of the organic matter
Organic matter
Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...

 in the soil is a highly contested issue: while the increase in the temperature would induce a greater rate in the production of minerals, lessening the soil organic matter content, the atmospheric CO2 concentration would tend to increase it.

Potential effects of global climate change on pests, diseases and weeds


A very important point to consider is that weeds would undergo the same acceleration of cycle as cultivated crops, and would also benefit from carbonaceous fertilization. Since most weeds are C3 plants, they are likely to compete even more than now against C4 crops such as corn. However, on the other hand, some results make it possible to think that weedkillers could gain in effectiveness with the temperature increase.

Global warming would cause an increase in rainfall in some areas, which would lead to an increase of atmospheric humidity and the duration of the wet season
Wet season
The the wet season, or rainy season, is the time of year, covering one or more months, when most of the average annual rainfall in a region occurs. The term green season is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the...

s. Combined with higher temperatures, these could favor the development of fungal diseases. Similarly, because of higher temperatures and humidity, there could be an increased pressure from insects and disease vectors.

Glacier retreat and disappearance


The continued retreat of glaciers will have a number of different quantitative impacts. In areas that are heavily dependent on water runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...

 from glaciers that melt during the warmer summer months, a continuation of the current retreat will eventually deplete the glacial ice and substantially reduce or eliminate runoff. A reduction in runoff will affect the ability to irrigate
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

 crops and will reduce summer stream flows necessary to keep dams and reservoirs replenished.

Approximately 2.4 billion people live in the drainage basin
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 of the Himalayan rivers. India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, China, Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...

, Afghanistan, Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...

, Nepal and Myanmar
Myanmar
Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....

 could experience floods followed by severe droughts in coming decades. In India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 alone, the Ganges provides water for drinking and farming for more than 500 million people. The west coast of North America, which gets much of its water from glaciers in mountain ranges such as the Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...

 and Sierra Nevada, also would be affected.

Ozone and UV-B


Some scientists think agriculture could be affected by any decrease in stratospheric ozone, which could increase biologically dangerous ultraviolet radiation B
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

. Excess ultraviolet radiation B can directly effect plant physiology
Physiology
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...

 and cause massive amounts of mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...

s, and indirectly through changed pollinator
Pollinator
A pollinator is the biotic agent that moves pollen from the male anthers of a flower to the female stigma of a flower to accomplish fertilization or syngamy of the female gamete in the ovule of the flower by the male gamete from the pollen grain...

 behavior, though such changes are simple to quantify. However, it has not yet been ascertained whether an increase in greenhouse gases would decrease stratospheric ozone levels.

In addition, a possible effect of rising temperatures is significantly higher levels of ground-level ozone
Tropospheric ozone
Ozone is a constituent of the troposphere . Photochemical and chemical reactions involving it drive many of the chemical processes that occur in the atmosphere by day and by night...

, which would substantially lower yields.

ENSO effects on agriculture


ENSO (El Niño Southern Oscillation) will affect monsoon patterns more intensely in the future as climate change warms up the ocean's water. Crops that lie on the equatorial belt or under the tropical Walker circulation, such as rice, will be affected by varying monsoon patterns and more unpredictable weather. Scheduled planting and harvesting based on weather patterns will become less effective.

Areas such as Indonesia where the main crop consists of rice will be more vulnerable to the increased intensity of ENSO effects in the future of climate change. University of Washington professor, David Battisti, researched the effects of future ENSO patterns on the Indonesian rice agriculture using [IPCC]'s 2007 annual report and 20 different logistical models mapping out climate factors such as wind pressure, sea-level, and humidity, and found that rice harvest will experience a decrease in yield. Bali and Java, which holds 55% of the rice yields in Indonesia, will be likely to experience 9–10% probably of delayed monsoon patterns, which prolongs the hungry season. Normal planting of rice crops begin in October and harevest by January. However, as climate change affects ENSO and consequently delays planting, harvesting will be late and in drier conditions, resulting in less potential yields.

Impact of agriculture on climate change


The agricultural sector is a driving force in the gas emissions and land use effects thought to cause climate change. In addition to being a significant user of land
Land use
Land use is the human use of land. Land use involves the management and modification of natural environment or wilderness into built environment such as fields, pastures, and settlements. It has also been defined as "the arrangements, activities and inputs people undertake in a certain land cover...

 and consumer of fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

, agriculture contributes directly to greenhouse gas emissions through practices such as rice production and the raising of livestock; according to the Intergovernmental Panel on Climate Change
Intergovernmental Panel on Climate Change
The Intergovernmental Panel on Climate Change is a scientific intergovernmental body which provides comprehensive assessments of current scientific, technical and socio-economic information worldwide about the risk of climate change caused by human activity, its potential environmental and...

, the three main causes of the increase in greenhouse gases observed over the past 250 years have been fossil fuels, land use, and agriculture.

Land use


Agriculture contributes to greenhouse gas increases through land use in four main ways:
  • CO2 releases linked to deforestation
    Deforestation
    Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....

  • Methane releases from rice cultivation
    Rice
    Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...

  • Methane releases from enteric fermentation
    Enteric fermentation
    Enteric fermentation is a digestive process by which carbohydrates are broken down by microorganisms into simple molecules for absorption into the bloodstream of an animal.It is one of the factors in increased methane emissions....

     in cattle
  • Nitrous oxide releases from fertilizer
    Fertilizer
    Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

     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.

The planet's major changes to land cover
Land Cover
Land cover is the physical material at the surface of the earth. Land covers include grass, asphalt, trees, bare ground, water, etc. There are two primary methods for capturing information on land cover: field survey and analysis of remotely sensed imagery....

 since 1750 have resulted from deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....

 in temperate regions: when forests and woodlands are cleared to make room for fields and pasture
Pasture
Pasture is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep or swine. The vegetation of tended pasture, forage, consists mainly of grasses, with an interspersion of legumes and other forbs...

s, the albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...

 of the affected area increases, which can result in either warming or cooling effects, depending on local conditions. Deforestation also affects regional carbon reuptake
RuBisCO
Ribulose-1,5-bisphosphate carboxylase oxygenase, commonly known by the shorter name RuBisCO, is an enzyme involved in the first major step of carbon fixation, a process by which atmospheric carbon dioxide is converted by plants to energy-rich molecules such as glucose. RuBisCo is an abbreviation...

, which can result in increased concentrations of CO2
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

, the dominant greenhouse gas. Land-clearing methods such as slash and burn
Slash and burn
Slash-and-burn is an agricultural technique which involves cutting and burning of forests or woodlands to create fields. It is subsistence agriculture that typically uses little technology or other tools. It is typically part of shifting cultivation agriculture, and of transhumance livestock...

 compound these effects by burning biomatter, which directly releases greenhouse gases and particulate matter such as soot
Soot
Soot is a general term that refers to impure carbon particles resulting from the incomplete combustion of a hydrocarbon. It is more properly restricted to the product of the gas-phase combustion process but is commonly extended to include the residual pyrolyzed fuel particles such as cenospheres,...

 into the air.

Livestock


Livestock and livestock-related activities such as deforestation and increasingly fuel-intensive farming practices are responsible for over 18% of human-made greenhouse gas emissions, including:
  • 9% of global carbon dioxide
    Carbon dioxide
    Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

     emissions
  • 35–40% of global methane
    Methane
    Methane is a chemical compound with the chemical formula . It is the simplest alkane, the principal component of natural gas, and probably the most abundant organic compound on earth. The relative abundance of methane makes it an attractive fuel...

     emissions (chiefly due to enteric fermentation
    Enteric fermentation
    Enteric fermentation is a digestive process by which carbohydrates are broken down by microorganisms into simple molecules for absorption into the bloodstream of an animal.It is one of the factors in increased methane emissions....

     and manure
    Manure
    Manure is organic matter used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil...

    )
  • 64% of global nitrous oxide
    Nitrous oxide
    Nitrous oxide, commonly known as laughing gas or sweet air, is a chemical compound with the formula . It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...

     emissions (chiefly due to fertilizer
    Fertilizer
    Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

     use.)


Livestock activities also contribute disproportionately to land-use effects, since crops such as corn
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...

 and alfalfa
Alfalfa
Alfalfa is a flowering plant in the pea family Fabaceae cultivated as an important forage crop in the US, Canada, Argentina, France, Australia, the Middle East, South Africa, and many other countries. It is known as lucerne in the UK, France, Australia, South Africa and New Zealand, and known as...

 are cultivated in order to feed the animals.

Worldwide, livestock production occupies 70% of all land used for agriculture, or 30% of the land surface of the Earth.

See also


  • Aridification
    Aridification
    Aridification is the process of a region becoming increasingly dry. It refers to long term change rather than seasonal variation.It is often measured as the reduction of average soil moisture content....

  • Biochar
    Biochar
    Biochar or terra preta is charcoal created by pyrolysis of biomass. Biochar is under investigation as an approach to carbon sequestration via bio-energy with carbon capture and storage. Biochar thus has the potential to help mitigate climate change, via carbon sequestration...

  • Desertification
    Desertification
    Desertification is the degradation of land in drylands. Caused by a variety of factors, such as climate change and human activities, desertification is one of the most significant global environmental problems.-Definitions:...

  • Drought
  • Environmental issues with agriculture
    Environmental issues with agriculture
    The environmental impact of agriculture varies based on the wide variety of agricultural practices employed around the world.-Climate change:Climate change and agriculture are interrelated processes, both of which take place on a global scale...

  • Fisheries and Climate Change
    Fisheries and climate change
    Rising ocean temperatures and ocean acidification are radically altering aquatic ecosystems. Climate change is modifying fish distribution and the productivity of marine and freshwater species...

  • Food security
    Food security
    Food security refers to the availability of food and one's access to it. A household is considered food-secure when its occupants do not live in hunger or fear of starvation. According to the World Resources Institute, global per capita food production has been increasing substantially for the past...

  • Global warming and wine
    Global warming and wine
    Global warming will affect wine in the same way it will affect many crops that require an intense amount of water and a high soil quality.An immediate effect of hotter weather is earlier ripening, which leads to a higher ethanol content; however, this cannot solely be contributed to climate...

  • International Assessment of Agricultural Science and Technology for Development
    International Assessment of Agricultural Science and Technology for Development
    The International Assessment of Agricultural Knowledge, Science and Technology for Development is an international effort initiated by the World Bank that evaluated the relevance, quality and effectiveness of agricultural knowledge, science, and technology , and the effectiveness of public and...

     addressing the links between climate change & agriculture
  • Land Allocation Decision Support System
    Land Allocation Decision Support System
    LADSS or Land Allocation Decision Support System, is an agricultural land use planning tool developed at The Macaulay Institute. More recently the term LADSS is used to refer to the research of the team behind the original planning tool....

     – a research tool that is used to test how climate change may affect agriculture (e.g. yield and quality)
  • Retreat of glaciers since 1850
    Retreat of glaciers since 1850
    The retreat of glaciers since 1850 affects the availability of fresh water for irrigation and domestic use, mountain recreation, animals and plants that depend on glacier-melt, and in the longer term, the level of the oceans...

  • Slash-and-char
    Slash-and-char
    Slash-and-char is an alternative to slash-and-burn that has a lesser effect on the environment. It is the practice of charring the biomass resulting from the slashing, instead of burning it as in the slash-and-burn practice....

  • Terra preta
    Terra preta
    Terra preta is a type of very dark, fertile anthropogenic soil found in the Amazon Basin. Terra preta owes its name to its very high charcoal content, and was indeed made by adding a mixture of charcoal, bone, and manure to the otherwise relatively infertile Amazonian soil, and stays there for...

  • Water crisis
    Water crisis
    Water crisis is a general term used to describe a situation where the available water within a region is less than the region's demand. The term has been used to describe the availability of potable water in a variety of regions by the United Nations and other world organizations...



Further reading

  • Fischer G., Shah M. and van Velthuizen H. (2002) "Climate Change and Agricultural Vulnerability". International Institute for Applied Systems Analysis. Report prepared under UN Institutional Contract Agreement 1113 for World Summit on Sustainable Development. Laxenburg, Austria

External links

  • Climate change on the Food and Agriculture Organization
    Food and Agriculture Organization
    The Food and Agriculture Organization of the United Nations is a specialised agency of the United Nations that leads international efforts to defeat hunger. Serving both developed and developing countries, FAO acts as a neutral forum where all nations meet as equals to negotiate agreements and...

     of the United Nations website.
  • A comprehensive report on the relationship between climate change, agriculture and food security by the International Food Policy Research Institute
    International Food Policy Research Institute
    The International Food Policy Research Institute is an international agricultural research center founded in the early 1970s to improve the understanding of national agricultural and food policies to promote the adoption of innovations in agricultural technology...

     (IFPRI). See also an overview of IFPRI's climate change research.
  • LADSS – Climate Change and Agriculture – Are we asking the right questions?
  • Food Security of Women in the Context of Climate Change – Online Discussion Forum
  • The Guardian's [climate change coverage http://www.guardian.co.uk/environment/climate-change] often includes discussions about food security, including the 30 June 2005 article,One in six countries facing food shortage
  • How is climate change threatening agriculture? section of official popularized version of IAASTD synthesis report (2008)
  • Impacts of Climate Change on European Forests and Options for Adaptation Report to the European Commission Directorate-General for Agriculture and Rural Development; report written by European Forest Institute (EFI) with University of Natural Resources and Applied Life Sciences, Vienna (BOKU), Institute of Forest Entomology, Forest Pathology and Forest Protection, INRA – UMR Biodiversité Gènes et Communautés and Italian Academy of Forest Sciences (IAFS) (November 2008)
  • Climate Change and Agriculture in the ECA region a regional look by the World Bank
    World Bank
    The World Bank is an international financial institution that provides loans to developing countries for capital programmes.The World Bank's official goal is the reduction of poverty...

     at climate change and agriculture in countries in Europe and Central Asia.
  • Climate Change, Agriculture and Food Security (Consultative Group on International Agricultural Research
    Consultative Group on International Agricultural Research
    The CGIAR is a strategic alliance that unites organizations involved in agricultural research for sustainable development with the donors that fund such work. These donors include governments of developing and industrialized countries, foundations and international and regional organizations...

    ) Global scientific research program that seeks to overcome the threats to agriculture and food security in a changing climate, exploring new ways of helping vulnerable rural communities adjust to global changes in climate.
  • Meat Eater's Guide to Climate Change + Health (Environmental Working Group & CleanMetrics Corp.) Life-cycle assessment (LCA) of greenhouse gas emissions associated with 20 types of meat, fish, dairy and vegetable proteins, as well as these foods’ effects on health.