Effects of climate change on agriculture
   HOME

TheInfoList



OR:

There are numerous effects of
climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
on agriculture, many of which are making it harder for agricultural activities to provide global
food security Food security is the state of having reliable access to a sufficient quantity of affordable, healthy Human food, food. The availability of food for people of any class, gender, ethnicity, or religion is another element of food protection. Simila ...
. Rising temperatures and changing weather patterns often result in lower crop yields due to
water scarcity Water scarcity (closely related to water stress or water crisis) is the lack of fresh water resources to meet the standard water demand. There are two types of water scarcity. One is ''physical.'' The other is ''economic water scarcity''. Physic ...
caused by
drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D.  Jiang, A.  Khan, W.  Pokam Mba, D.  Rosenfeld, J. Tierney, ...
,
heat wave A heat wave or heatwave, sometimes described as extreme heat, is a period of abnormally hot weather generally considered to be at least ''five consecutive days''. A heat wave is usually measured relative to the usual climate in the area and ...
s and
flood A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant con ...
ing. These
effects of climate change Effects of climate change are well documented and growing for Earth's natural environment and human societies. Changes to the climate system include an Instrumental temperature record, overall warming trend, Effects of climate change on the ...
can also increase the risk of several regions suffering simultaneous
crop failure Harvesting is the process of collecting plants, animals, or fish (as well as fungi) as food, especially the process of gathering mature crops, and "the harvest" also refers to the collected crops. Reaping is the cutting of grain or pulses fo ...
s. Currently this risk is rare but if these simultaneous crop failures occur, they could have significant consequences for the global food supply. Many
pests PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...
and plant diseases are expected to become more prevalent or to spread to new regions. The world's
livestock Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...
are expected to be affected by many of the same issues. These issues range from greater heat stress to
animal feed Animal feed is food given to domestic animals, especially livestock, in the course of animal husbandry. There are two basic types: fodder and forage. Used alone, the word ''feed'' more often refers to fodder. Animal feed is an important input ...
shortfalls and the spread of
parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...
s and
vector-borne disease In epidemiology, a disease vector is any living agent that carries and transmits an infectious pathogen such as a parasite or microbe, to another living organism. Agents regarded as vectors are mostly blood-sucking ( hematophagous) arthropods such ...
s. The increased atmospheric level from human activities (mainly burning of
fossil fuels A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geologica ...
) causes a fertilization effect. This effect offsets a small portion of the detrimental effects of climate change on agriculture. However, it comes at the expense of lower levels of essential
micronutrient Micronutrients are essential chemicals required by organisms in small quantities to perform various biogeochemical processes and regulate physiological functions of cells and organs. By enabling these processes, micronutrients support the heal ...
s in the crops. Furthermore, CO2 fertilization has little effect on C4 crops like
maize Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout grass that produces cereal grain. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte. Native American ...
. On the coasts, some agricultural land is expected to be lost to
sea level rise The sea level has been rising from the end of the last ice age, which was around 20,000 years ago. Between 1901 and 2018, the average sea level rose by , with an increase of per year since the 1970s. This was faster than the sea level had e ...
, while melting glaciers could result in less
irrigation Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has bee ...
water being available. On the other hand, more
arable land Arable land (from the , "able to be ploughed") is any land capable of being ploughed and used to grow crops.''Oxford English Dictionary'', "arable, ''adj''. and ''n.''" Oxford University Press (Oxford), 2013. Alternatively, for the purposes of a ...
may become available as frozen land thaws. Other effects include erosion and changes in
soil fertility Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality.
and the length of growing seasons. Bacteria like ''
Salmonella ''Salmonella'' is a genus of bacillus (shape), rod-shaped, (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two known species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' ...
'' and
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
that produce
mycotoxins A mycotoxin (from the Greek μύκης , "fungus" and τοξικός , "poisonous") is a toxic secondary metabolite produced by fungi and is capable of causing disease and death in both humans and other animals. The term 'mycotoxin' is usually r ...
grow faster as the climate warms. Their growth has negative effects on
food safety Food safety (or food hygiene) is used as a scientific method/discipline describing handling, food processing, preparation, and food storage, storage of food in ways that prevent foodborne illness. The occurrence of two or more cases of a simi ...
, food loss and
prices A price is the (usually not negative) quantity of payment or compensation expected, required, or given by one party to another in return for goods or services. In some situations, especially when the product is a service rather than a phys ...
. Extensive research exists on the effects of climate change on individual crops, particularly on the four
staple crop A staple food, food staple, or simply staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard diet for an individual or a population group, supplying a large fraction of energy needs an ...
s:
corn Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout Poaceae, grass that produces cereal grain. It was domesticated by indigenous peoples of Mexico, indigenous peoples in southern Mexico about 9,000 years ago ...
(maize),
rice Rice is a cereal grain and in its Domestication, domesticated form is the staple food of over half of the world's population, particularly in Asia and Africa. Rice is the seed of the grass species ''Oryza sativa'' (Asian rice)—or, much l ...
,
wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...
and
soybeans The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source of f ...
. These crops are responsible for around two-thirds of all calories consumed by humans (both directly and indirectly as animal feed). The research investigates important uncertainties, for example future population growth, which will increase global food demand for the foreseeable future. The future degree of
soil erosion Soil erosion is the denudation or wearing away of the Topsoil, upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, Atmosphere of Ea ...
and groundwater depletion are further uncertainties. On the other hand, a range of improvements to agricultural yields, collectively known as the
Green Revolution The Green Revolution, or the Third Agricultural Revolution, was a period during which technology transfer initiatives resulted in a significant increase in crop yields. These changes in agriculture initially emerged in Developed country , devel ...
, has increased yields per unit of land area by between 250% and 300% since 1960. Some of that progress will likely continue. Global food security will change relatively little in the near-term. 720 million to 811 million people were undernourished in 2021, with around 200,000 people being at a ''catastrophic level'' of food insecurity. Climate change is expected to add an additional 8 to 80 million people who are at risk of hunger by 2050. The estimated range depends on the intensity of future warming and the effectiveness of adaptation measures. Agricultural productivity growth will likely have improved food security for hundreds of millions of people by then. Predictions that reach further into the future (to 2100 and beyond) are rare. There is some concern about the effects on food security from more
extreme weather Extreme weather includes unexpected, unusual, severe weather, severe, or unseasonal weather; weather at the extremes of the historical distribution—the range that has been seen in the past. Extreme events are based on a location's recorded weat ...
events in future. Nevertheless, at this stage there is no expectation of a widespread global
famine A famine is a widespread scarcity of food caused by several possible factors, including, but not limited to war, natural disasters, crop failure, widespread poverty, an Financial crisis, economic catastrophe or government policies. This phenom ...
due to climate change within the 21st century.Mycoo, M., M. Wairiu, D. Campbell, V. Duvat, Y. Golbuu, S. Maharaj, J. Nalau, P. Nunn, J. Pinnegar, and O. Warrick, 2022
Chapter 3: Mitigation pathways compatible with long-term goals
I
Climate Change 2022: Mitigation of Climate Change
K. Riahi, R.Schaeffer, J.Arango, K. Calvin, C. Guivarch, T. Hasegawa, K. Jiang, E. Kriegler, R. Matthews, G. P. Peters, A. Rao, S. Robertson, A. M. Sebbit, J. Steinberger, M. Tavoni, D. P. van Vuuren Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 463–464 , doi= 10.1017/9781009157926.005


Direct effects from changing weather patterns


Observed changes in adverse weather conditions

Agriculture is sensitive to weather, and major events like heatwaves or
drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D.  Jiang, A.  Khan, W.  Pokam Mba, D.  Rosenfeld, J. Tierney, ...
s or heavy rains (also known as low and high
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...
extremes) can cause substantial losses. For example,
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
's farmers are very likely to suffer losses during the
El Nino EL, El or el may refer to: Arts and entertainment Fictional entities * El, a character from the manga series ''Shugo Chara!'' by Peach-Pit * Eleven (''Stranger Things'') (El), a fictional character in the TV series ''Stranger Things'' * El, fami ...
weather conditions, while 2003 European heat wave led to 13 billion
euro The euro (currency symbol, symbol: euro sign, €; ISO 4217, currency code: EUR) is the official currency of 20 of the Member state of the European Union, member states of the European Union. This group of states is officially known as the ...
s in uninsured agriculture losses. Climate change is known to increase the frequency and severity of heatwaves, and to make precipitation less predictable and more prone to extremes, but since climate change attribution is still a relatively new field, connecting specific weather events and the shortfalls they cause to climate change over natural variability is often difficult. Exceptions include
West Africa West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...
, where the climate-induced intensification of
extreme weather Extreme weather includes unexpected, unusual, severe weather, severe, or unseasonal weather; weather at the extremes of the historical distribution—the range that has been seen in the past. Extreme events are based on a location's recorded weat ...
was found to have already decreased
millet Millets () are a highly varied group of small-seeded grasses, widely grown around the world as cereal crops or grains for fodder and human food. Most millets belong to the tribe Paniceae. Millets are important crops in the Semi-arid climate, ...
yields by 10–20%, and
sorghum ''Sorghum bicolor'', commonly called sorghum () and also known as great millet, broomcorn, guinea corn, durra, imphee, jowar, or milo, is a species in the Poaceae, grass genus ''Sorghum (genus), Sorghum'' cultivated for its grain. The grain i ...
yields 5–15%. Similarly, it was found that climate change had intensified drought conditions in
Southern Africa Southern Africa is the southernmost region of Africa. No definition is agreed upon, but some groupings include the United Nations geoscheme for Africa, United Nations geoscheme, the intergovernmental Southern African Development Community, and ...
in 2007, which elevated food prices and caused "acute food insecurity" in the country of
Lesotho Lesotho, formally the Kingdom of Lesotho and formerly known as Basutoland, is a landlocked country in Southern Africa. Entirely surrounded by South Africa, it is the largest of only three sovereign enclave and exclave, enclaves in the world, t ...
. Agriculture in Southern Africa was also adversely affected by drought after climate change intensified the effects of
2014–2016 El Niño event The 2014–2016 El Niño was the strongest El Niño event on record, with unusually warm waters developing between the coast of South America and the International Date Line. These unusually warm waters influenced the world's weather in a number ...
. In
Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
, between 1950 and 2019, heat extremes became more frequent and more likely to occur consecutively, while cold extremes have declined. At the same time,
Northern Europe The northern region of Europe has several definitions. A restrictive definition may describe northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other ge ...
and much of
Eastern Europe Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural and socio-economic connotations. Its eastern boundary is marked by the Ural Mountain ...
was found to experience extreme
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...
more often, while the
Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...
became more affected by
drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D.  Jiang, A.  Khan, W.  Pokam Mba, D.  Rosenfeld, J. Tierney, ...
. Similarly, the severity of heatwave and drought effects on European crop production was found to have tripled over a 50-year period – from losses of 2.2% during 1964–1990 to losses of 7.3% in 1991–2015. Available under CC BY 4.0. In the summer of 2018, heat waves probably linked to climate change greatly reduced average yield in many parts of the world, especially Europe. During the month of August, more crop failures resulted in a rise in global
food prices Food prices refer to the average price level for food across countries, regions and on a global scale. Food prices affect producers and consumers of food. Price levels depend on the food production process, including food marketing and food di ...
. On the other hand, floods, often linked to climate change, have also had notable adverse effects on agriculture in the recent years. In May 2019, floods shortened
corn Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout Poaceae, grass that produces cereal grain. It was domesticated by indigenous peoples of Mexico, indigenous peoples in southern Mexico about 9,000 years ago ...
planting season in the
Midwestern United States The Midwestern United States (also referred to as the Midwest, the Heartland or the American Midwest) is one of the four census regions defined by the United States Census Bureau. It occupies the northern central part of the United States. It ...
, lowering the projected yield from 15 billion
bushel A bushel (abbreviation: bsh. or bu.) is an Imperial unit, imperial and United States customary units, US customary unit of volume, based upon an earlier measure of dry capacity. The old bushel was used mostly for agriculture, agricultural pr ...
s to 14.2. During the 2021 European floods, estimates pointed to severe damage to the agricultural sector of Belgium, one of the countries hardest hit by the floods, including long-term effects like
soil erosion Soil erosion is the denudation or wearing away of the Topsoil, upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, Atmosphere of Ea ...
. In
China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
, 2023 research found that extreme rainfall had cost the country about 8% of its rice output over the two preceding decades. This was considered comparable to losses caused by extreme heat over this period.


Projected effects from temperature increase

Changes in temperature and weather patterns will alter areas suitable for farming. The current prediction is that temperatures will increase and precipitation will decrease in
arid Aridity is the condition of geographical regions which make up approximately 43% of total global available land area, characterized by low annual precipitation, increased temperatures, and limited water availability.Perez-Aguilar, L. Y., Plata ...
and
semi-arid A semi-arid climate, semi-desert climate, or steppe climate is a aridity, dry climate sub-type. It is located on regions that receive precipitation below Evapotranspiration#Potential evapotranspiration, potential evapotranspiration, but not as l ...
regions (
Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...
,
Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...
,
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
, Southwest United States, and
Southern Europe Southern Europe is also known as Mediterranean Europe, as its geography is marked by the Mediterranean Sea. Definitions of southern Europe include some or all of these countries and regions: Albania, Andorra, Bosnia and Herzegovina, Bulgaria, C ...
). In addition, crop yields in
tropical regions The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...
will be negatively affected by the projected moderate increase in temperature (1–2 °C) expected to occur during the first half of the century. During the second half of the century, further warming is projected to decrease
crop A crop is a plant that can be grown and harvested extensively for profit or subsistence. In other words, a crop is a plant or plant product that is grown for a specific purpose such as food, Fiber, fibre, or fuel. When plants of the same spe ...
yields in all regions including
Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
and the
Northern United States The Northern United States, commonly referred to as the American North, the Northern States, or simply the North, is a geographical and historical region of the United States. History Early history Before the 19th century westward expansion, the ...
. Many
staple crop A staple food, food staple, or simply staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard diet for an individual or a population group, supplying a large fraction of energy needs an ...
s are extremely sensitive to heat and when temperatures rise over , soybean seedlings are killed and corn pollen loses its vitality. According to some estimates, a 1 °C increase in global temperature could result in a 5–10% decline in crop yields in the future. Higher winter temperatures and more frost-free days in some regions can currently be disruptive, as they can cause phenological mismatch between flowering time of plants and the activity of
pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female carpel, stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are ...
s, threatening their reproductive success. In the longer term, however, they would result in longer
growing season A season is a division of the year marked by changes in weather, ecology, and the amount of daylight. The growing season is that portion of the year in which local conditions (i.e. rainfall, temperature, daylight) permit normal plant growth. Whi ...
s. For example, a 2014 study found that maize yields in the
Heilongjiang Heilongjiang is a province in northeast China. It is the northernmost and easternmost province of the country and contains China's northernmost point (in Mohe City along the Amur) and easternmost point (at the confluence of the Amur and Us ...
region of China increased by between 7 and 17% per decade as a result of rising temperatures. On the other hand, a year 2017
meta-analysis Meta-analysis is a method of synthesis of quantitative data from multiple independent studies addressing a common research question. An important part of this method involves computing a combined effect size across all of the studies. As such, th ...
comparing data from four different methods of estimating effect of warming (two types of climate model, statistical regressions and
field experiment Field experiments are experiments carried out outside of laboratory settings. They randomly assign subjects (or other sampling units) to either treatment or control groups to test claims of causal relationships. Random assignment helps establ ...
s where land around certain crops was warmed by a certain amount to compare them with the controls) concluded that on a global scale, warming alone has consistently negative effects on the yields of four most important crops, suggesting that any increases would be down to
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...
changes and the
CO2 fertilization effect The CO2 fertilization effect or carbon fertilization effect causes an increased rate of photosynthesis while limiting leaf transpiration in plants. Both processes result from increased levels of atmospheric carbon dioxide (CO2). The carbon fert ...
.


Heat stress in livestock


Changes in agricultural water availability and reliability

Both
droughts A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D.  Jiang, A.  Khan, W.  Pokam Mba, D.  Rosenfeld, J. Tierney, ...
and
floods A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant con ...
contribute to decreases in
crop yield In agriculture, the yield is a measurement of the amount of a crop grown, or product such as wool, meat or milk produced, per unit area of land. The seed ratio is another way of calculating yields. Innovations, such as the use of fertilizer, the ...
s. On average, climate change increases the overall amount of water contained in the atmosphere by 7% per every , thus increasing
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...
. However, this increase in precipitation is not distributed evenly in space (
atmospheric circulation Atmospheric circulation is the large-scale movement of Atmosphere of Earth, air and together with ocean circulation is the means by which thermal energy is redistributed on the surface of the Earth. The Earth's atmospheric circulation varies fro ...
patterns already cause different areas to receive different amounts of rainfall) or time: heavy rainfall, with the potential to cause floods, becomes more frequent. This means that under the probable mid-range
climate change scenario A climate change scenario is a hypothetical future based on a "set of key driving forces".IPCC, 2022Annex I: Glossary an Diemen, R., J.B.R. Matthews, V. Möller, J.S. Fuglestvedt, V. Masson-Delmotte, C.  Méndez, A. Reisinger, S. Semenov (eds) In ...
, SSP2-4.5, precipitation events globally will become larger by 11.5%, yet the time between them will increase by an average of 5.1%. Under the highest-emission scenario SSP5-8.5, there will be an 18.5% increase in size of events and 9.6% increase in the duration between them. At the same time, water losses by plants through evotranspiration will increase almost everywhere due to higher temperatures. While the fertilization effect also reduces such losses by plants, it depends on the area's climate which effect will dominate. As such, the 2020–2023 Horn of Africa drought has been primarily attributed to the great increase in evotranspiration exacerbating the effect of persistent low rainfall, which would have been more manageable in the cooler preindustrial climate. In total, this means that
drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D.  Jiang, A.  Khan, W.  Pokam Mba, D.  Rosenfeld, J. Tierney, ...
s have been occurring more frequently on average because of climate change. Africa, southern Europe, the Middle East, most of the Americas, Australia, South and Southeast Asia are the parts of the globe where droughts are expected to become more frequent and intense in spite of the global increase in precipitation. Droughts disturb , and these effects can be aggravated by
population growth Population growth is the increase in the number of people in a population or dispersed group. The World population, global population has grown from 1 billion in 1800 to 8.2 billion in 2025. Actual global human population growth amounts to aroun ...
and urban expansion spurring on increased demand for water. The ultimate outcome is
water scarcity Water scarcity (closely related to water stress or water crisis) is the lack of fresh water resources to meet the standard water demand. There are two types of water scarcity. One is ''physical.'' The other is ''economic water scarcity''. Physic ...
, which results in crop failures and the loss of pasture grazing land for livestock, exacerbating pre-existing
poverty Poverty is a state or condition in which an individual lacks the financial resources and essentials for a basic standard of living. Poverty can have diverse Biophysical environmen ...
in
developing countries A developing country is a sovereign state with a less-developed Secondary sector of the economy, industrial base and a lower Human Development Index (HDI) relative to developed countries. However, this definition is not universally agreed upon. ...
and leading to
malnutrition Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is a deficiency, excess, or imbalance of energy, protein and other nutrients which adversely affects the body's tissues a ...
and potentially
famine A famine is a widespread scarcity of food caused by several possible factors, including, but not limited to war, natural disasters, crop failure, widespread poverty, an Financial crisis, economic catastrophe or government policies. This phenom ...
.
Irrigation Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has bee ...
of crops is able to reduce or even remove the effects on yields of lower rainfall and higher temperatures – through localized cooling.  However, using water resources for irrigation has downsides and is expensive. Further, some sources of irrigation water may become less reliable. This includes irrigation driven by water runoff from
glaciers A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
during the summer, as there has already been an observed
retreat of glaciers since 1850 The retreat of glaciers since 1850 is a well-documented effects of climate change, effect of climate change. The retreat of Mountain glacier, mountain glaciers provides evidence for the Instrumental temperature record, rise in global temperatures ...
, and it is expected to continue, depleting the glacial ice and reducing or outright eliminating runoff. In Asia, global warming of will reduce the ice mass of Asia's high mountains by about 29–43%,: Approximately 2.4 billion people live in the
drainage basin A drainage basin is an area of land in which all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...
of the Himalayan rivers: In
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
alone, the river
Ganges The Ganges ( ; in India: Ganga, ; in Bangladesh: Padma, ). "The Ganges Basin, known in India as the Ganga and in Bangladesh as the Padma, is an international which goes through India, Bangladesh, Nepal and China." is a trans-boundary rive ...
provides water for drinking and farming for more than 500 million people. In the
Indus River The Indus ( ) is a transboundary river of Asia and a trans-Himalayas, Himalayan river of South Asia, South and Central Asia. The river rises in mountain springs northeast of Mount Kailash in the Western Tibet region of China, flows northw ...
watershed, these mountain water resources contribute to up to 60% of irrigation outside of the monsoon season, and an additional 11% of total crop production. Since
Effects of climate change on the water cycle The effects of climate change on the water cycle are profound and have been described as an ''intensification'' or a ''strengthening'' of the water cycle (also called hydrologic cycle).Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, ...
are projected to substantially increase precipitation in all but the westernmost parts of the watershed, the loss of the glaciers is expected to be offset: however, agriculture in the region will become more reliable on monsoon than ever, and
hydropower Hydropower (from Ancient Greek -, "water"), also known as water power or water energy, is the use of falling or fast-running water to Electricity generation, produce electricity or to power machines. This is achieved by energy transformation, ...
generation would become less predictable and reliable.


Effects on plants caused by increasing atmospheric and methane

Plants respond to increased atmospheric carbon dioxide concentrations through multiple physiological changes. Atmospheric
carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
() increases affect plant growth patterns and physiological functions in multiple ways. Higher levels of carbon dioxide amplify both crop yields and biomass production through enhanced
photosynthetic Photosynthesis ( ) is a Biological system, system of biological processes by which Photoautotrophism, photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical ener ...
processes. The partial closure of
stomata In botany, a stoma (: stomata, from Greek ''στόμα'', "mouth"), also called a stomate (: stomates), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange between the internal air spa ...
under elevated levels leads to reduced plant water loss and enhances water-use efficiency. Elevated atmospheric CO₂ and CH₄ concentrations can have a range of effects on plant growth, physiology and ecosystem process via multiple pathways. In the case of C₃ plants, CO₂ fertilization usually more than doubles the initial stimulation of photosynthesis by increased CO₂, resulting in increased rates of carbon assimilation, vegetative growth, and, under some circumstances, crop yield. This so-called CO₂ fertilization effect has been demonstrated in controlled systems, such as Free-Air CO₂ Enrichment (FACE) trials that are designed to mimic predicted future atmospheric conditions and monitor plant responses under open-air conditions. Moreover, increased CO₂ can cause partial stomatal closing to reduce transpiration, and enhance water use-efficiency in plant, especially under drought stress. However, the benefits of CO₂ enrichment may be moderated by nutrient limitations, particularly nitrogen and phosphorus, which constrain biomass accumulation in natural ecosystems. Methane, while less directly involved in photosynthesis, contributes to climate warming and alters plant communities indirectly through changes in temperature, precipitation patterns, and soil conditions. In wetland environments, increased atmospheric methane can enhance methanotrophic activity in the rhizosphere, influencing nutrient cycling and root-microbe interactions. Furthermore, elevated greenhouse gas levels may affect plant-insect interactions, pathogen dynamics, and secondary metabolite production, complicating predictions about future ecosystem health and productivity.


Higher yields due to fertilization

Although the greening of vegetated parts of Earth has been noted, the continuing positive effect of fertilization will remain uncertain over the long-term. It has been reported that the positive effects of elevated on plant growth may be attenuated by nutrient limitations, particularly N and P, which are crucial for biomass production and long-term productivity.Leakey, A.D.B. (2019). "Climate change: What does elevated CO₂ do to crops?". Current Biology. 29(19): R953–R954. doi:10.1016/j.cub.2019.07.021.Terrer, C., Jackson, R.B., Prentice, I.C. et al. (2021). "Nitrogen and phosphorus constrain the CO₂ fertilization of global plant biomass". Nature Climate Change. 11: 730–735. doi:10.1038/s41558-021-01063-1. Moreover, although satellite data indicate a widespread increase in LAI, the greening trend does not necessarily translate into a proportionate increase in carbon sequestration, because of reduced carbon residence times and enhanced ecosystem respiration with warming, as well as unaccounted carbon losses.Zhu, Z. et al. (2016). "Greening of the Earth and its drivers". Nature Climate Change. 6: 791–795. doi:10.1038/nclimate3004.Piao, S., Sitch, S., Ciais, P. et al. (2010). "The carbon balance of terrestrial ecosystems in China". Nature. 458: 1009–1013. doi:10.1038/nature07944. Thus, despite enhancing global greening through fertilization, the potential for it to compensate for anthropogenic emissions appears to be restricted without corresponding adjustments to nutrient supply and land management.Reich, P.B. et al. (2014). "Plant growth enhancement by elevated CO₂ eliminated by joint water and nitrogen limitation". Nature Geoscience. 7: 920–924. doi:10.1038/ngeo2284.


Reduced nutritional value of crops

Changes in atmospheric
carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
may reduce the
nutrition Nutrition is the biochemistry, biochemical and physiology, physiological process by which an organism uses food and water to support its life. The intake of these substances provides organisms with nutrients (divided into Macronutrient, macro- ...
al quality of some crops, with for instance wheat having less protein and less of some minerals. The nutritional quality of
C3 plants carbon fixation is the most common of three metabolic pathways for carbon fixation in photosynthesis, the other two being and CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into two molecules of ...
(e.g. wheat, oats, rice) is especially at risk: lower levels of protein as well as minerals (for example zinc and iron) are expected.Bezner Kerr, R., T. Hasegawa, R. Lasco, I. Bhatt, D. Deryng, A. Farrell, H. Gurney-Smith, H. Ju, S. Lluch-Cota, F. Meza, G. Nelson, H. Neufeldt, and P. Thornton, 2022
Chapter 5: Food, Fibre, and Other Ecosystem Products
In
Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change
.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.) Cambridge University Press, Cambridge, UK and New York, NY, USA, doi:10.1017/9781009325844.007.
Food crops could see a reduction of
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
,
iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...
and
zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...
content in common food crops of 3 to 17%. This is the projected result of food grown under the expected atmospheric carbon-dioxide levels of 2050. Using data from the UN Food and Agriculture Organization as well as other public sources, the authors analysed 225 different staple foods, such as
wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...
,
rice Rice is a cereal grain and in its Domestication, domesticated form is the staple food of over half of the world's population, particularly in Asia and Africa. Rice is the seed of the grass species ''Oryza sativa'' (Asian rice)—or, much l ...
,
maize Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout grass that produces cereal grain. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte. Native American ...
,
vegetable Vegetables are edible parts of plants that are consumed by humans or other animals as food. This original meaning is still commonly used, and is applied to plants collectively to refer to all edible plant matter, including edible flower, flo ...
s, roots and
fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...
s. The effect of increased levels of atmospheric carbon dioxide on the nutritional quality of plants is not limited only to the above-mentioned crop categories and nutrients. A 2014
meta-analysis Meta-analysis is a method of synthesis of quantitative data from multiple independent studies addressing a common research question. An important part of this method involves computing a combined effect size across all of the studies. As such, th ...
has shown that crops and wild plants exposed to elevated
carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
levels at various latitudes have lower density of several minerals such as magnesium, iron, zinc, and potassium. Studies using Free-Air Concentration Enrichment have also shown that increases in CO2 lead to decreased concentrations of
micronutrient Micronutrients are essential chemicals required by organisms in small quantities to perform various biogeochemical processes and regulate physiological functions of cells and organs. By enabling these processes, micronutrients support the heal ...
s in crop and non-crop plants with negative consequences for human nutrition, including decreased B vitamins in rice. This may have knock-on effects on other parts of
ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...
s as herbivores will need to eat more food to gain the same amount of protein. A 2022 narrative review highlighted that climate change not only impacts food quantity but also reduces the nutritional quality of crops. Elevated atmospheric CO₂ levels have been found to lower concentrations of protein, iron, zinc, and other micronutrients in major staple foods such as wheat and rice. These nutrient losses can lead to widespread deficiencies, particularly in vulnerable populations, and contribute to increased risks of malnutrition. The authors emphasize that climate-smart agriculture and sustainable food systems are urgently needed to protect both food security and human health in the face of these challenges. Empirical evidence shows that increasing levels of result in lower concentrations of many minerals in plant tissues. Doubling levels results in an 8% decline, on average, in the concentration of minerals. Declines in magnesium, calcium, potassium, iron, zinc and other minerals in crops can worsen the quality of human nutrition. Researchers report that the levels expected in the second half of the 21st century will likely reduce the levels of zinc, iron, and protein in wheat, rice, peas, and soybeans. Some two billion people live in countries where citizens receive more than 60 per cent of their zinc or iron from these types of crops. Deficiencies of these nutrients already cause an estimated loss of 63 million life-years annually. Alongside a decrease in minerals, evidence shows that plants contain 6% more carbon, 15% less nitrogen, 9% less phosphorus, and 9% less sulfur at double conditions. The increase in carbon is mostly attributed to
carbohydrates A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ma ...
without a structural role in plants – the human-digestable, calorie-providing starch and simple sugars. The decrease in nitrogen translates directly into a decrease in the protein content. As a result, higher not only reduce a plant's micronutrients, but also the quality of its macronutrient combination. These nutritional declines have severe consequences for public health worldwide, and especially in areas where they have traditionally consumed plant-based diets. Populations in low- and middle-income countries are particularly at risk, having staple crops like rice and wheat as the primary sources of their daily protein, iron and zinc.Smith, M.R., Myers, S.S. (2018). "Impact of anthropogenic CO₂ emissions on global human nutrition". Nature Climate Change. 8(9): 834–839. doi:10.1038/s41558-018-0253-3.Potential nutrient losses as a result of changes in crop composition due to CO 2 could make any deficiencies that already exist worse and increase the incidence of anemia, stunting, and the development of cognitive skills.Myers, S.S. et al. (2014). "Increasing CO₂ threatens human nutrition". Nature. 510: 139–142. doi:10.1038/nature13179. Apart from the effect on humans, such changes in nutrient content can cascade through food webs, with herbivores needing to ingest more biomass to meet their dietary needs, which could have implications for ecosystem dynamics.Loladze, I. (2014). "Hidden shift of the ionome of plants exposed to elevated CO₂ depletes minerals at the base of human nutrition". eLife. 3: e02245. doi:10.7554/eLife.02245. These results highlight the importance of not just looking at crop yields in future climate scenarios, but also at the nutritional merits of yields in terms of their potential to support human and ecological health.Long, S.P. et al. (2015). "Food for thought: lower-than-expected crop yield stimulation with rising CO₂ concentrations". Science. 349(6250): 142–143. doi:10.1126/science.aac4257.


Increasing damages from surface-level ozone

Anthropogenic
methane emissions Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% (360 million tons) of methane r ...
have a significant contribution to warming due to the high
global warming potential Global warming potential (GWP) is a measure of how much heat a greenhouse gas traps in the atmosphere over a specific time period, relative to carbon dioxide (). It is expressed as a multiple of warming caused by the same mass of carbon dioxide ( ...
of methane. At the same time, methane also acts as a precursor to surface ozone, which is a significant
air pollutant Air pollution is the presence of substances in the air that are harmful to humans, other living beings or the environment. Pollutants can be gases like ozone or nitrogen oxides or small particles like soot and dust. It affects both outdoor ...
. Its effects include lowering physiological functions and therefore the yield and quality of crops. Following methane levels, tropospheric ozone levels "increased substantially since the late 19th century", and according to a 2016 estimate, the four major crops (see later section) experienced yield losses of 5±1.5% relative to a no-climate change scenario due to ozone increases alone, which is nearly half of the negative effects caused by the other effects of climate change (10.9±3.2%), and cancels out most of the fertilization effect (6.5±1.0%).


Changes in the extent and quality of agricultural land


Erosion and soil 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 Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...
and
soil degradation Soil retrogression and degradation are two regressive evolution processes associated with the loss of equilibrium of a soil health, stable soil. Retrogression is primarily due to soil erosion and corresponds to a phenomenon where succession revert ...
is more likely to occur.
Soil fertility Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality.
would also be affected by global warming. Increased erosion in agricultural landscapes from anthropogenic factors can occur with losses of up to 22% of soil carbon in 50 years. Climate change will also cause soils to warm. Elevated temperatures can accelerate the decomposition of soil organic matter, resulting in nutrient loss from the soil. These factors collectively contribute to reduced soil quality, thus affecting crop growth.In turn, this could cause the soil microbe population size to dramatically increase 40–150%. Warmer conditions would favour growth of certain bacteria species, shifting the bacterial community composition. Elevated carbon dioxide would increase the growth rates of plants and soil microbes, slowing the soil carbon cycle and favouring
oligotroph An oligotroph is an organism that can live in an environment that offers very low levels of nutrients. They may be contrasted with copiotrophs, which prefer nutritionally rich environments. Oligotrophs are characterized by slow growth, low rates o ...
s, which are slower-growing and more resource efficient than
copiotroph A copiotroph is an organism found in environments rich in nutrients, particularly carbon. They are the opposite to oligotrophs, which survive in much lower carbon concentrations. Copiotrophic organisms tend to grow in high organic substrate condi ...
s.


Agricultural land loss from sea level rise

A rise in the sea level would result in an agricultural
land loss Land loss is the term typically used to refer to the conversion of coastal land to open water by natural processes and human activities. The term ''land loss'' includes coastal erosion. It is a much broader term than coastal erosion because land l ...
, in particular in areas such as
South East Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...
.
Erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...
, submergence of shorelines,
salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...
of the
water table The water table is the upper surface of the phreatic zone or zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with groundwater, which may be fresh, saline, or brackish, depending on the loc ...
due to the increased sea levels, could mainly affect agriculture through
inundation A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant concern in agriculture, civi ...
of low-lying lands. Low-lying areas such as
Bangladesh Bangladesh, officially the People's Republic of Bangladesh, is a country in South Asia. It is the List of countries and dependencies by population, eighth-most populous country in the world and among the List of countries and dependencies by ...
,
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
and
Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...
will experience major loss of rice crop if sea levels rise as expected by the end of the century. Vietnam for example relies heavily on its southern tip, where the
Mekong Delta The Mekong Delta ( or simply ), also known as the Western Region () or South-western region (), is the list of regions of Vietnam, region in southwestern Vietnam where the Mekong, Mekong River River delta, approaches and empties into the sea th ...
lies, for rice planting. A one-metre rise in sea level will cover several square kilometres of rice paddies in Vietnam. Besides simply flooding agricultural land, sea level rise can also cause
saltwater intrusion Saltwater intrusion is the movement of saline water into freshwater aquifers, which can lead to groundwater quality degradation, including drinking water sources, and other consequences. Saltwater intrusion can naturally occur in coastal aquifers, ...
into freshwater
well A well is an excavation or structure created on the earth by digging, driving, or drilling to access liquid resources, usually water. The oldest and most common kind of well is a water well, to access groundwater in underground aquifers. The ...
s, particularly if they are already below sea level. Once the concentration of saltwater exceeds 2–3%, the well becomes unusable. Notably, areas along an estimated 15% of the US coastline already have the majority of local
groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...
below the sea level.


Thawing of potentially arable land

Climate change may increase the amount of
arable land Arable land (from the , "able to be ploughed") is any land capable of being ploughed and used to grow crops.''Oxford English Dictionary'', "arable, ''adj''. and ''n.''" Oxford University Press (Oxford), 2013. Alternatively, for the purposes of a ...
by reducing the amount of frozen land. 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 effect 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. The
Arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...
region is expected to benefit from increased opportunities for agriculture and
forestry Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests and woodlands for associated resources for human and Natural environment, environmental benefits. Forestry is practiced in plantations and ...
.


Response of insects, plant diseases and weeds

Climate change will alter pest,
plant disease Plant diseases are diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like or ...
and
weed A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...
distributions, with potential to reduce crop yields, including of staple crops like
wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...
,
soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...
s, and corn (maize). Warmer temperatures can increase the
metabolic rate Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...
and number of breeding cycles of
insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
populations. Historically, cold temperatures at night and in the
winter Winter is the coldest and darkest season of the year in temperate and polar climates. It occurs after autumn and before spring. The tilt of Earth's axis causes seasons; winter occurs when a hemisphere is oriented away from the Sun. Dif ...
months would kill off
insects Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...
,
bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...
and
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
. The warmer, wetter winters are promoting fungal plant diseases like wheat rusts ( stripe and brown/leaf) and soybean rust to travel northward. The increasing incidence of flooding and heavy rains also promotes the growth of various other plant pests and diseases.


Insect pollinators and pests

Climate change is expected to have a negative effect on many insects, greatly reducing their
species distribution Species distribution, or species dispersion, is the manner in which a biological taxon is spatially arranged. The geographic limits of a particular taxon's distribution is its range, often represented as shaded areas on a map. Patterns of distr ...
and thus increasing their risk of going extinct. Around 9% of agricultural production is dependent in some way on insect pollination, and some
pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female carpel, stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are ...
species are also adversely affected, with wild
bumblebee A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only Extant taxon, extant group in the tribe Bombini, though a few extinct r ...
s known to be particularly vulnerable to recent warming. At the same time, insects are the most diverse animal taxa, and some species will benefit from the changes, including notable agricultural pests and
disease vectors In epidemiology, a disease vector is any living agent that carries and transmits an infectious pathogen such as a parasite or microbe, to another living organism. Agents regarded as vectors are mostly blood-sucking ( hematophagous) arthropods such ...
. Insects that previously had only two breeding cycles per year could gain an additional cycle if warm growing seasons extend, causing a population boom. Temperate places and higher
latitude In geography, latitude is a geographic coordinate system, geographic coordinate that specifies the north-south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at t ...
s are more likely to experience a dramatic change in insect populations: for instance, the Mountain Pine Beetle epidemic in
British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...
,
Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
had killed millions of pine trees, partially because the winters were not cold enough to slow or kill the growing beetle larvae. Likewise, potato tuber moth and
Colorado potato beetle The Colorado potato beetle (''Leptinotarsa decemlineata''; also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle, and the potato bug) is a beetle known for being a major pest of potato crops. It is about lo ...
are predicted to spread into areas currently too cold for them. Further,
effects of climate change on the water cycle The effects of climate change on the water cycle are profound and have been described as an ''intensification'' or a ''strengthening'' of the water cycle (also called hydrologic cycle).Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, ...
often mean that both wet seasons and drought seasons will become more intense. Some insect species will breed more rapidly because they are better able to take advantage of such changes in conditions. This includes certain insect pests, such as
aphids Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...
and
whiteflies Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described. Description and taxonomy The A ...
: similarly,
locust Locusts (derived from the Latin ''locusta'', locust or lobster) are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstances they b ...
swarms could also cause more damage as the result. A notable example was the 2019–2022 locust infestation focused on
East Africa East Africa, also known as Eastern Africa or the East of Africa, is a region at the eastern edge of the Africa, African continent, distinguished by its unique geographical, historical, and cultural landscape. Defined in varying scopes, the regi ...
, considered the worst of its kind in many decades. The fall armyworm, ''Spodoptera frugiperda'', is a highly invasive plant pest, which can cause have massive damage to crops, especially maize. In the recent years, it has spread to countries in
sub-Saharan Africa Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...
, and this spread is linked to climate change. It is expected that these highly invasive crop pests will spread to other parts of the planet since they have a high capacity to adapt to different environments.


Invasive plant species


Weeds

A changing climate may favour the more biologically diverse
weed A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...
s over the monocrops on many farms. Characteristics of weeds such as their
genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...
,
cross-breeding A crossbreed is an organism with purebred parents of two different breeds, varieties, or populations. A domestic animal of unknown ancestry, where the breed status of only one parent or grandparent is known, may also be called a crossbreed though ...
ability, and fast-growth rates put them at an advantage in changing climates as these characteristics allow them to adapt readily in comparison to most farm's uniform crops, and give them a biological advantage. Weeds also undergo the same acceleration of cycles as cultivated crops, and would also benefit from CO2 fertilization. Since most weeds are
C3 plants carbon fixation is the most common of three metabolic pathways for carbon fixation in photosynthesis, the other two being and CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into two molecules of ...
, they are likely to compete even more than now against C4 crops such as corn. The increased levels are also expected to increase the tolerance of weeds to
herbicides Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...
, reducing their efficiency. However, this may be counteracted by increased temperatures elevating their effectiveness.


Plant pathogens

Currently, pathogens result in losses of 10–16% of the global harvest and this level is likely to rise as plants are at an ever-increasing risk of exposure to pests and
pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...
s. Research has shown that climate change may alter the developmental stages of plant pathogens that can affect crops. This includes several pathogens associated with potato blackleg disease (e.g.
Dickeya ''Dickeya'' is a genus of the family Pectobacteriaceae that consists mainly of pathogens from herbaceous plants. Dickeya is the result of the reclassification of 75 strains of ''Pectobacterium chrysanthemi'', as well as '' Brenneria paradisiaca' ...
), as they grow and reproduce faster at higher temperatures. The warming is also expected to elevate
food safety Food safety (or food hygiene) is used as a scientific method/discipline describing handling, food processing, preparation, and food storage, storage of food in ways that prevent foodborne illness. The occurrence of two or more cases of a simi ...
issues and food spoilage caused by
mycotoxin A mycotoxin (from the Greek μύκης , "fungus" and τοξικός , "poisonous") is a toxic secondary metabolite produced by fungi and is capable of causing disease and death in both humans and other animals. The term 'mycotoxin' is usually rese ...
-producing fungi, and bacteria such as
Salmonella ''Salmonella'' is a genus of bacillus (shape), rod-shaped, (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two known species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' ...
. Climate change 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 The wet season (sometimes called the rainy season or monsoon season) is the time of year when most of a region's average annual rainfall occurs. Generally, the season lasts at least one month. The term ''green season'' is also sometimes used a ...
s. Combined with higher temperatures, these conditions could favour the development of
fungal A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as one of the tradit ...
diseases, such as late blight, or bacterial infections such as Ralstonia solanacearum, which may also be able to spread more easily through flash flooding. Climate change has the capability of altering pathogen and host interactions, specifically the rates of pathogen infection and the resistance of the host plant. Also affected by plant disease are the economic costs associated with growing different plants that might yield less profit as well as treating and managing already diseased crops. For instance, soybean rust is a vicious plant pathogen that can kill off entire fields in a matter of days, devastating farmers and costing billions in agricultural losses. Change in weather patterns and temperature due to climate change leads to dispersal of plant pathogens as hosts migrate to areas with more favourable conditions. This increases crop losses due to diseases. For instance,
aphids Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...
act as vectors for many potato
virus A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are ...
es and will be able to spread further due to increased temperatures.


Effects on crop yields


Observed effects

According to the
IPCC Sixth Assessment Report The Sixth Assessment Report (AR6) of the United Nations (UN) Intergovernmental Panel on Climate Change (IPCC) is the sixth in a series of reports which assess the available scientific information on climate change. Three Working Groups (WGI, II, ...
from 2022, there is ''high confidence'' that in and of itself, climate change to date has left primarily negative effects on both
crop yield In agriculture, the yield is a measurement of the amount of a crop grown, or product such as wool, meat or milk produced, per unit area of land. The seed ratio is another way of calculating yields. Innovations, such as the use of fertilizer, the ...
s and quality of produce, although there has been some regional variation: more negative effects have been observed for some crops in low-latitudes (maize and wheat), while positive effects of climate change have been observed in some crops in high-latitudes (maize, wheat, and
sugar beet A sugar beet is a plant whose root contains a high concentration of sucrose and that is grown commercially for sugar production. In plant breeding, it is known as the Altissima cultivar group of the common beet (''Beta vulgaris''). Together with ...
s). I.e. during the period 1981 to 2008, global warming has had negative effects on wheat yield in especially tropical regions, with decreases in average global yields by 5.5%.  A study in 2019 tracked ~20,000 political units globally for 10 crops (
maize Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout grass that produces cereal grain. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte. Native American ...
,
rice Rice is a cereal grain and in its Domestication, domesticated form is the staple food of over half of the world's population, particularly in Asia and Africa. Rice is the seed of the grass species ''Oryza sativa'' (Asian rice)—or, much l ...
,
wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...
,
soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...
,
barley Barley (), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains; it was domesticated in the Fertile Crescent around 9000 BC, giving it nonshattering spikele ...
,
cassava ''Manihot esculenta'', common name, commonly called cassava, manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America, from Brazil, Paraguay and parts of the Andes. Although ...
,
oil palm ''Elaeis'' () is a genus of palms, called oil palms, containing two species, native to Africa and the Americas. They are used in commercial agriculture in the production of palm oil. Description Mature palms are single-stemmed, and can gro ...
,
rapeseed Rapeseed (''Brassica napus'' subsp. ''napus''), also known as rape and oilseed rape and canola, is a bright-yellow flowering member of the family Brassicaceae (mustard or cabbage family), cultivated mainly for its oil-rich seed, which naturall ...
,
sorghum ''Sorghum bicolor'', commonly called sorghum () and also known as great millet, broomcorn, guinea corn, durra, imphee, jowar, or milo, is a species in the Poaceae, grass genus ''Sorghum (genus), Sorghum'' cultivated for its grain. The grain i ...
and
sugarcane Sugarcane or sugar cane is a species of tall, Perennial plant, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar Sugar industry, production. The plants are 2–6 m (6–20 ft) tall with stout, jointed, fib ...
), providing more detail on the spatial resolution and a larger number of crops than previously studied. It found that crop yields across Europe, sub-Saharan Africa, and Australia had in general decreased because of climate change (compared to the baseline value of 2004–2008 average data), though exceptions are present. The effect of global climate change on yields of different crops from climate trends ranged from −13.4% (oil palm) to 3.5% (soybean). The study also showed that effects are generally positive in Latin America. Effects in Asia and Northern and Central America are mixed. While the
Green Revolution The Green Revolution, or the Third Agricultural Revolution, was a period during which technology transfer initiatives resulted in a significant increase in crop yields. These changes in agriculture initially emerged in Developed country , devel ...
had ensured the growth of overall crop production per land area of 250% to 300% since the 1960, with around 44% attributed to newer crop varieties alone, it is believed this growth would have been even greater without the counteracting role of climate change on major crop yields over the same period. Between 1961 and 2021, global agricultural productivity could have been 21% greater than it actually was, if it did not have to contend with climate change. Such shortfalls would have affected
food security Food security is the state of having reliable access to a sufficient quantity of affordable, healthy Human food, food. The availability of food for people of any class, gender, ethnicity, or religion is another element of food protection. Simila ...
of vulnerable populations the most: a study in 2019 showed that climate change has already increased the risk of food insecurity in many food insecure countries. Even in
developed countries A developed country, or advanced country, is a sovereign state that has a high quality of life, developed economy, and advanced technological infrastructure relative to other less industrialized nations. Most commonly, the criteria for eval ...
such as
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
, extreme weather associated with climate change has been found to cause a wide range of cascading spillovers through
supply chain A supply chain is a complex logistics system that consists of facilities that convert raw materials into finished products and distribute them to end consumers or end customers, while supply chain management deals with the flow of goods in distri ...
disruption, in addition to its primary effect on fruit, vegetable, and livestock sectors and the rural communities reliant on them. Between 1961 and 1985,
cereal A cereal is a grass cultivated for its edible grain. Cereals are the world's largest crops, and are therefore staple foods. They include rice, wheat, rye, oats, barley, millet, and maize ( Corn). Edible grains from other plant families, ...
production more than doubled in
developing nations A developing country is a sovereign state with a less-developed industrial base and a lower Human Development Index (HDI) relative to developed countries. However, this definition is not universally agreed upon. There is also no clear agreemen ...
, largely due to the development of irrigation, fertilizer, and seed varieties. Ch. 4 Even in the absence of further scientific/technological developments, many of the existing advancements have not been evenly distributed, and their spread from the
developed world A developed country, or advanced country, is a sovereign state that has a high quality of life, developed economy, and advanced technological infrastructure relative to other less industrialized nations. Most commonly, the criteria for eval ...
to the
developing world A developing country is a sovereign state with a less-developed industrial base and a lower Human Development Index (HDI) relative to developed countries. However, this definition is not universally agreed upon. There is also no clear agreeme ...
is expected to drive some improvements on its own. Further,
agricultural expansion Agricultural expansion describes the growth of agricultural land ( arable land, pastures, etc.) especially in the 20th and 21st centuries. The agricultural expansion is often explained as a direct consequence of the global increase in food and e ...
has slowed down in the recent years, but this trend is widely expected to reverse in the future in order to maintain the global food supply under all but the most optimistic
climate change scenario A climate change scenario is a hypothetical future based on a "set of key driving forces".IPCC, 2022Annex I: Glossary an Diemen, R., J.B.R. Matthews, V. Möller, J.S. Fuglestvedt, V. Masson-Delmotte, C.  Méndez, A. Reisinger, S. Semenov (eds) In ...
s consistent with the
Paris Agreement The Paris Agreement (also called the Paris Accords or Paris Climate Accords) is an international treaty on climate change that was signed in 2016. The treaty covers climate change mitigation, adaptation, and finance. The Paris Agreement was ...
.


Generalized yield projections

In 2007, the
IPCC Fourth Assessment Report ''Climate Change 2007'', the Fourth Assessment Report (AR4) of the United Nations Intergovernmental Panel on Climate Change (IPCC), was published in 2007 and is the fourth in a series of reports intended to assess scientific, technical and soci ...
had suggested that global production potential would increase up to around of globally averaged warming, as productivity increases for cereals in high latitudes would outweigh decreases in the low latitudes and global aggregate yields of rain-fed agriculture would increase by 5–20% in the first half of the 21st century. Warming exceeding this level would very likely see global declines in yields. Since then, subsequent reports had been more negative on the global production potential. The
US National Research Council The National Academies of Sciences, Engineering, and Medicine (NASEM), also known as the National Academies, is a congressionally chartered organization that serves as the collective scientific national academy of the United States. The name i ...
assessed the literature on the effects of climate change on crop yields in 2011, and provided central estimates for key crops. A meta-analysis in 2014 revealed consensus that yield is expected to decrease in the second half of the century, and with greater effect in tropical than temperate regions. A 2024 comprehensive review by Yuan et al. found that, under high‐emission scenarios without adaptation, the combined effects of rising temperatures, altered precipitation patterns and increased evapotranspiration are projected to reduce yields of the four staple cereals (maize, rice, wheat and soybean) by approximately 5–10 % by mid-century.


Effects on yields for four major crops

There is a large number of agricultural
crop A crop is a plant that can be grown and harvested extensively for profit or subsistence. In other words, a crop is a plant or plant product that is grown for a specific purpose such as food, Fiber, fibre, or fuel. When plants of the same spe ...
s, but not all of them are equally important. Most climate change assessments focus on "four major crops" –
maize Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout grass that produces cereal grain. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte. Native American ...
(corn),
rice Rice is a cereal grain and in its Domestication, domesticated form is the staple food of over half of the world's population, particularly in Asia and Africa. Rice is the seed of the grass species ''Oryza sativa'' (Asian rice)—or, much l ...
,
wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...
and
soybeans The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source of f ...
– which are consumed directly and indirectly, as
animal feed Animal feed is food given to domestic animals, especially livestock, in the course of animal husbandry. There are two basic types: fodder and forage. Used alone, the word ''feed'' more often refers to fodder. Animal feed is an important input ...
(the main purpose of soybeans). The three
cereal A cereal is a grass cultivated for its edible grain. Cereals are the world's largest crops, and are therefore staple foods. They include rice, wheat, rye, oats, barley, millet, and maize ( Corn). Edible grains from other plant families, ...
s are collectively responsible for half of the total human
calorie The calorie is a unit of energy that originated from the caloric theory of heat. The large calorie, food calorie, dietary calorie, kilocalorie, or kilogram calorie is defined as the amount of heat needed to raise the temperature of one liter o ...
intake, and together with soybeans, they account for two thirds. Different methods have been used to project future yields of these crops, and by 2019, the consensus was that warming would lead to aggregate declines of the four. Maize and
soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...
would decrease with any warming, whereas rice and wheat production might peak at of warming. In 2021, a paper which used an ensemble of 21
climate model Numerical climate models (or climate system models) are mathematical models that can simulate the interactions of important drivers of climate. These drivers are the atmosphere, oceans, land surface and ice. Scientists use climate models to st ...
s estimated that under the most intense
climate change scenario A climate change scenario is a hypothetical future based on a "set of key driving forces".IPCC, 2022Annex I: Glossary an Diemen, R., J.B.R. Matthews, V. Möller, J.S. Fuglestvedt, V. Masson-Delmotte, C.  Méndez, A. Reisinger, S. Semenov (eds) In ...
used at the time, RCP8.5, global yields of these four crops would decline by between 3–12% around 2050 and by 11–25% by the year 2100. The losses were concentrated in what are currently the major agricultural producers and exporters. For instance, even by 2050, some agricultural areas of
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
,
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
,
South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...
, Southeast China,
Southern Europe Southern Europe is also known as Mediterranean Europe, as its geography is marked by the Mediterranean Sea. Definitions of southern Europe include some or all of these countries and regions: Albania, Andorra, Bosnia and Herzegovina, Bulgaria, C ...
and the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
would suffer production losses of mostly maize and soybeans exceeding 25%. A similar finding - that some major "breadbaskets" would begin to see unequivocal effects of climate change, both positive and negative, before the year 2040 - had been established in another study from the same year. Since it represents the worst-case scenario of continually increasing emissions with no efforts to reduce them, RCP8.5 is often considered unrealistic, and a less intense RCP4.5 scenario (which still leads to nearly by century's end, far in excess of the
Paris Agreement The Paris Agreement (also called the Paris Accords or Paris Climate Accords) is an international treaty on climate change that was signed in 2016. The treaty covers climate change mitigation, adaptation, and finance. The Paris Agreement was ...
goals) is now usually considered a better match for the current trajectory. In addition, reduced crop yields have the potential to increase food prices and negatively affect agricultural prosperity world-wide, with a 0.3% annual loss in prospective global GDP by 2100. This will negatively impact the means of subsistence for millions of people particularly in South Asian Nations. Over 70% of people in the Asian region depend on agriculture for their livelihood, it employs nearly 60 percent of the workforce and provides 22% of the gross domestic product (GDP) for the area.


Maize

Out of the four crops, maize is considered the most vulnerable to warming, with one meta-analysis concluding that every of global warming reduces maize yields by 7.4%. It is also a
C4 carbon fixation carbon fixation or the Hatch–Slack pathway is one of three known photosynthetic processes of carbon fixation in plants. It owes the names to the 1960s discovery by Marshall Davidson Hatch and Charles Roger Slack. fixation is an addition ...
plant, meaning that it experiences little benefit from the increased levels. When the results from modelling experiments comparing the combined output of latest
earth system model Earth system science (ESS) is the application of systems science to the Earth. In particular, it considers interactions and 'feedbacks', through material and energy fluxes, between the Earth's sub-systems' cycles, processes and "spheres"—atmosp ...
s and dedicated agricultural crop models were published in 2021, the most notable new finding was the substantial reduction in projected global yields of maize. While the previous generation suggested that under the low-warming scenario, maize productivity would increase by around 5% by the end of the century, the latest had shown a reduction of 6% under the equivalent scenario, SSP1-2.6. Under the high-emission SSP5-8.5, there was a global decline of 24% by 2100, as opposed to the earlier suggestion of a 1% increase.


Rice

Studies indicate that on their own, temperature changes reduce global rice yields by 3.2% for every of global warming. Projections become more complicated once the changes in precipitation, fertilization effect and other factors need to be taken into account: for instance, climate effects on rice growth in
East Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...
had been a net positive so far, although 2023 research suggested that by the end of the century,
China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
could lose up to 8% of its rice yield due to increases in extreme rainfall events alone. As of 2021, global projections of rice yields from the most advanced climate and agricultural models were less consistent than they were for wheat and maize, and less able to identify a clear statistically significant trend.


Wheat

Climate change effects on rainfed
wheat Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...
will vary depending on the region and local climatic conditions. Studies in
Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...
surrounding changes in temperature and rainfall are representative for several different parts of the world since there exists a wide range of climatic conditions. They range from temperate to hot-arid to cold semi-arid. Scenarios based on increasing temperature by up to and rainfall decreases by up to 25% show wheat grain yield losses can be significant. The losses can be as much as 45% in temperate areas and over 50% in hot-arid areas. But in cold semi-arid areas yields can be increased somewhat (about 15%). Adaptation strategies with the most promise center around dates for seed planting. Late planting in November to January can have significant positive effects on yields due to the seasonality of rainfall. However, those experiments did not consider the effects of increases. Globally, temperature changes alone are expected to reduce annual wheat yield by 6% for every of global warming. However, other factors such as precipitation and the fertilization effect benefit wheat yields far more. In November 2021, the results from modelling experiments comparing the combined output of latest
earth system model Earth system science (ESS) is the application of systems science to the Earth. In particular, it considers interactions and 'feedbacks', through material and energy fluxes, between the Earth's sub-systems' cycles, processes and "spheres"—atmosp ...
s and dedicated agricultural crop models were published. While it projected a consistent decrease in future global yields of maize, particularly under greater warming, it found the opposite for wheat yields. When the previous generation of models suggested a 9% increase in global wheat yields by 2100 under the high-emission scenario, the updated results indicate that under its highest-warming SSP5-8.5 scenario, they would increase by 18%. As per projections, heat-induced stress could potentially affect approximately half of the Indo-Gangetic Plains (IGP), making it unsuitable for the cultivation of wheat by 2050.


Soybeans

Studies have shown that when levels rise,
soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...
leaves are less nutritious; therefore plant-eating beetles have to eat more to get their required
nutrients A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...
. In addition, soybeans are less capable of defending themselves against the predatory insects under high . The diminishes the plant's
jasmonic acid Jasmonic acid (JA) is an organic compound found in several plants including jasmine. The molecule is a member of the jasmonate class of plant hormones. It is biosynthesized from linolenic acid by the octadecanoid pathway. It was first isolated ...
production, an insect-killing poison that is excreted when the plant senses it is being attacked. Without this protection, beetles are able to eat the soybean leaves freely, resulting in a lower crop yield. This is not a problem unique to soybeans, and many plant species' defence mechanisms are impaired in a high environment. Studies indicate that on their own, temperature changes reduce global soybean yields by 3.1% for every of global warming. These projections become more complicated once the changes in precipitation, fertilization effect and other factors need to be taken into account: as of 2021, global projections of soybean yields from the most advanced climate and agricultural models were less able to establish a strong trend when compared to the projections for maize and wheat.


Other crops

Climate change induced by increasing
greenhouse gas Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...
es is likely to differ across crops and countries.


Millet and sorghum

Millet Millets () are a highly varied group of small-seeded grasses, widely grown around the world as cereal crops or grains for fodder and human food. Most millets belong to the tribe Paniceae. Millets are important crops in the Semi-arid climate, ...
and
sorghum ''Sorghum bicolor'', commonly called sorghum () and also known as great millet, broomcorn, guinea corn, durra, imphee, jowar, or milo, is a species in the Poaceae, grass genus ''Sorghum (genus), Sorghum'' cultivated for its grain. The grain i ...
are not as widely consumed as the four major crops, but they are crucial staples in many
Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...
n countries. A paper published in the year 2022 found that under the highest-warming SSP5-8.5 scenario, changes in temperature and
soil moisture Soil moisture is the water content of the soil. It can be expressed in terms of volume or weight. Soil moisture measurement can be based on ''in situ'' probes (e.g., capacitance probes, neutron probes) or remote sensing methods. Water that enters ...
would reduce the aggregate yields of millet, sorghum, maize and soybeans by between 9% and 32%, depending on the model. Notably, this was a less pessimistic result than in the earlier models, which the authors attributed to simulating soil moisture directly, rather than attempting to indirectly account for it by tracking
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...
changes caused by
effects of climate change on the water cycle The effects of climate change on the water cycle are profound and have been described as an ''intensification'' or a ''strengthening'' of the water cycle (also called hydrologic cycle).Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, ...
.


Lentils (besides soybeans)

Climate change induced drought stress in Africa will likely lead to a reduction in the nutritional quality of the common bean. This would primarily impact populations in poorer countries less able to compensate by eating more food, more varied diets, or possibly taking supplements.


Potatoes

As well as affecting potatoes directly, climate change will also affect the distributions and populations of many potato diseases and pests. For instance, late blight is predicted to become a greater threat in some areas (e.g. in
Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...
) and become a lesser threat in others (e.g. in the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
Altogether, one 2003 estimate suggests that future (2040–2069) worldwide potato yield would be 18–32% lower than it was at the time, driven by declines in hotter areas like Sub-Saharan Africa, unless farmers and potato cultivars can adapt to the new environment.


Grapevines (wine production)


Effects on livestock rearing


Global food security and undernutrition

Scientific understanding of how climate change would affect global
food security Food security is the state of having reliable access to a sufficient quantity of affordable, healthy Human food, food. The availability of food for people of any class, gender, ethnicity, or religion is another element of food protection. Simila ...
has evolved over time. The latest
IPCC Sixth Assessment Report The Sixth Assessment Report (AR6) of the United Nations (UN) Intergovernmental Panel on Climate Change (IPCC) is the sixth in a series of reports which assess the available scientific information on climate change. Three Working Groups (WGI, II, ...
in 2022 suggested that by 2050, the number of people at risk of hunger will increase under all scenarios by between 8 and 80 million people, with nearly all of them in
Sub-Saharan Africa Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...
,
South Asia South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...
and
Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...
. However, this comparison was done relative to a world where no climate change had occurred, and so it does not rule out the possibility of an overall reduction in hunger risk when compared to present-day conditions. The earlier
Special Report on Climate Change and Land The United Nations' Intergovernmental Panel on Climate Change's (IPCC) Special Report on Climate Change and Land (SRCCL), also known as the "Special Report on climate change, desertification, land degradation, sustainable land management, food se ...
suggested that under a relatively high emission scenario (RCP6.0), cereals may become 1–29% more expensive in 2050 depending on the socioeconomic pathway. Compared to a scenario where climate change is absent, this would put between 1–181 million people with low income at risk of hunger. It is difficult to project the effect of climate change on utilization (protecting food against spoilage, being healthy enough to absorb nutrients, etc.). In 2016, a modelling study suggested that by mid-century, the most intense climate change scenario would reduce per capita global food availability by 3.2%, with a 0.7% decrease in
red meat In gastronomy, red meat is commonly red when raw (and a dark color after it is cooked), in contrast to white meat, which is pale in color before (and after) cooking. In culinary terms, only flesh from mammals or fowl (not fish) is classified ...
consumption and a 4% decrease in
fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...
and
vegetable Vegetables are edible parts of plants that are consumed by humans or other animals as food. This original meaning is still commonly used, and is applied to plants collectively to refer to all edible plant matter, including edible flower, flo ...
consumption. According to its numbers, 529,000 people would die between 2010 and 2050 as the result, primarily in
South Asia South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...
and
East Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...
: two-thirds of those deaths would be caused by the lack of
micronutrient Micronutrients are essential chemicals required by organisms in small quantities to perform various biogeochemical processes and regulate physiological functions of cells and organs. By enabling these processes, micronutrients support the heal ...
s from reduced
fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...
and
vegetable Vegetables are edible parts of plants that are consumed by humans or other animals as food. This original meaning is still commonly used, and is applied to plants collectively to refer to all edible plant matter, including edible flower, flo ...
supply, rather than outright starvation. Acting to slow climate change would reduce these projections by up to 71%.
Food prices Food prices refer to the average price level for food across countries, regions and on a global scale. Food prices affect producers and consumers of food. Price levels depend on the food production process, including food marketing and food di ...
are also expected to become more volatile. As of 2017, around 821 million people had suffered from hunger. This was equivalent to about 11% of the world population: regionally, this included 23.2% of
sub-Saharan Africa Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...
, 16.5% of the
Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...
and 14.8% of
South Asia South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...
. In 2021, 720 million to 811 million people were considered undernourished in 2021 (of whom 200,000, 32.3 million and 112.3 million people were at a "catastrophic", "emergency" and "crisis" levels of food insecurity, respectively). In 2020, research suggested that the baseline projected level of socioeconomic development ( Shared Socioeconomic Pathway 2) would reduce this number to 122 million globally by 2050, even as the population grows to reach 9.2 billion. The effect of climate change would at most increase this 2050 figure by around 80 million, and the negative effect could be reduced to 20 million through enabling easier food trade with measures such as eliminating
tariff A tariff or import tax is a duty (tax), duty imposed by a national Government, government, customs territory, or supranational union on imports of goods and is paid by the importer. Exceptionally, an export tax may be levied on exports of goods ...
s. In 2021, a
meta-analysis Meta-analysis is a method of synthesis of quantitative data from multiple independent studies addressing a common research question. An important part of this method involves computing a combined effect size across all of the studies. As such, th ...
of 57 studies on food security was more pessimistic, suggesting that the year 2050 population at risk of hunger would be around 500 million under SSP2. Some variations of
Shared Socioeconomic Pathways Shared Socioeconomic Pathways (SSPs) are climate change scenarios of projected socioeconomic global changes up to 2100 as defined in the IPCC Sixth Assessment Report on climate change in 2021. They are used to derive greenhouse gas emissions sc ...
with high climate change and a lack of equitable
global development International development or global development is a broad concept denoting the idea that societies and countries have differing levels of economic or human development on an international scale. It is the basis for international classification ...
instead resulted in an outright increase of global hunger by up to 30% from its 2010 levels. For the earlier
IPCC Fourth Assessment Report ''Climate Change 2007'', the Fourth Assessment Report (AR4) of the United Nations Intergovernmental Panel on Climate Change (IPCC), was published in 2007 and is the fourth in a series of reports intended to assess scientific, technical and soci ...
in 2007, the analysis of four main SRES pathways had shown with ''medium confidence'' (about 50% certainty)) that trends of
social Social organisms, including human(s), live collectively in interacting populations. This interaction is considered social whether they are aware of it or not, and whether the exchange is voluntary or not. Etymology The word "social" derives fro ...
and
economic development In economics, economic development (or economic and social development) is the process by which the economic well-being and quality of life of a nation, region, local community, or an individual are improved according to targeted goals and object ...
in three of them (A1, B1, B2) would see the number of undernourished people decline to 100–130 million people by the year 2080, while trends in A2 projected 770 million undernourished – similar to the contemporary (early 21st century) figures of ~700 million people. Once the effect of climate change implied by those scenarios was taken into account, A1, B1 and B2 scenarios would see 100–380 million undernourished by 2080 (still a major decline in
hunger In politics, humanitarian aid, and the social sciences, hunger is defined as a condition in which a person does not have the physical or financial capability to eat sufficient food to meet basic nutritional needs for a sustained period. In t ...
from 2006 levels), and A2 would see 740–1,300 million, although there was only ''low'' (20% certainty) to ''medium'' certainty in these figures.
Sub-Saharan Africa Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...
would likely overtake
Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...
as the world's most food-insecure region, primarily due to differing socioeconomic trends.


Effects of extreme weather and synchronized crop failures

Some scientists consider the aforementioned projections of crop yields and food security of limited use, because in their view, they primarily model climate change as a change in mean climate state, and are not as well-equipped to consider climatic extremes. For instance, a paper published in 2021 had also attempted to calculate the number of people facing hunger in 2050 – but now on the assumption that a climate event with a 1% (i.e. once in 100 years) likelihood of occurring in the ''new'' climate (meaning it would have been effectively impossible in the present climate) were to impact that year. It estimated that such an event would increase the baseline number by 11–33% even in the low-emission scenario, and by 20–36% in the high-emission one. If such an event were to affect more vulnerable regions like
South Asia South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...
, then they would have required triple their 2021 level of known food reserves to absorb the blow. Notably, other papers show that simulating recent historical extreme events in climate models, such as the 2003 European heatwave, typically results in lower effects than what had been observed in the real world, indicating that the effects of future extreme events are also likely to be underestimated. The difference between climatic mean and extremes may be particularly important for determining areas where agriculture may stop being viable. In 2021, a research team aimed to extend
climate model Numerical climate models (or climate system models) are mathematical models that can simulate the interactions of important drivers of climate. These drivers are the atmosphere, oceans, land surface and ice. Scientists use climate models to st ...
projections of mean changes in temperature and the water cycle to the year 2500. They suggested that under the second-strongest warming scenario RCP6.0, land area capable of supporting four major temperate crops (maize, potato, soybean and wheat) would become about 11% smaller by 2100 and 18.3% smaller by 2500, while for major tropical crops (
cassava ''Manihot esculenta'', common name, commonly called cassava, manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America, from Brazil, Paraguay and parts of the Andes. Although ...
, rice,
sweet potato The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledonous plant in the morning glory family, Convolvulaceae. Its sizeable, starchy, sweet-tasting tuberous roots are used as a root vegetable, which is a staple food in parts of ...
,
sorghum ''Sorghum bicolor'', commonly called sorghum () and also known as great millet, broomcorn, guinea corn, durra, imphee, jowar, or milo, is a species in the Poaceae, grass genus ''Sorghum (genus), Sorghum'' cultivated for its grain. The grain i ...
,
taro Taro (; ''Colocasia esculenta'') is a root vegetable. It is the most widely cultivated species of several plants in the family Araceae that are used as vegetables for their corms, leaves, stems and Petiole (botany), petioles. Taro corms are a ...
, and yam), it would decline by only 2.3% around 2100, yet by around 15% by 2500. Under the low-emission scenario RCP2.6, changes are much smaller, with around 3% decline in suitable land area for temperate crops by 2500 and an equivalent gain for tropical crops by then. Yet, another paper from 2021 suggested that by 2100, under the high-emission SSP5-8.5, 31% and 34% of the current crop and livestock production would leave what the authors have defined as a "safe climatic space": that is, those areas (most of
South Asia South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...
and the
Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...
, as well as parts of
sub-Saharan Africa Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...
and
Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...
) would experience very rapid shift in
Holdridge life zones The Holdridge life zones system is a global bioclimatic scheme for the classification of land areas. It was first published by Leslie Holdridge in 1947, and updated in 1967. It is a relatively simple system based on few empirical data, giving ob ...
(HLZ) and associated weather, while also being low in social resilience. Notably, a similar fraction of global crop and livestock production would also experience a large change in HLZ, but in more developed areas which would have better chances of adapting. In contrast, under the low-emissions SSP1-2.6, 5% and 8% of crop and livestock production would leave what is defined as the safe climatic space. Also in 2021, it was suggested that the high-emission scenario would result in a 4.5-fold increase in the probability of breadbasket failures (defined as a yield loss of 10% or more) by 2030, which could then increase 25 times by 2050. This corresponds to reaching and thresholds under that scenario: earlier research suggested that for maize, this would increase risks for multiple simultaneous breadbasket failures (yield loss of 10% or more) from 6% under the late-20th century climate to 40% and 54%, respectively. Some countries are particularly dependent on imports from certain exporters, meaning that a crop failure in those countries would hit them disproportionately. I.e. a ban on export of staple crops from
Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
,
Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...
and the
United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
alone would place around 200 million people (90% from Sub-Saharan Africa) at risk of starvation. Additionally, there is the issue of representing synchronization - where extreme climate events happen to strike multiple important producer regions around the same time. It was estimated that if hypothetically, every region with a synchronized growing season were to experience crop failure at the same time, it would cause losses of four major crops between 17% and 34%. More realistically, analysis of historic data suggested that there have already been synchronized climate events associated with up to 20% yield losses. According to a 2016 estimate, if global maize, rice and wheat exports declined by 10%, 55 million people in 58 poor countries lose at least 5% of their food supply. Further, two specific
Rossby wave Rossby waves, also known as planetary waves, are a type of inertial wave naturally occurring in rotating fluids. They were first identified by Sweden-born American meteorologist Carl-Gustaf Arvid Rossby in the Earth's atmosphere in 1939. They ...
pattern are known to induce simultaneous heat extremes in either
Eastern Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of China, Japan, South Korea, and Taiwan ...
,
Eastern Europe Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural and socio-economic connotations. Its eastern boundary is marked by the Ural Mountain ...
and Central North America, or in
Western Asia West Asia (also called Western Asia or Southwest Asia) is the westernmost region of Asia. As defined by most academics, UN bodies and other institutions, the subregion consists of Anatolia, the Arabian Peninsula, Iran, Mesopotamia, the Armenian ...
,
Western Europe Western Europe is the western region of Europe. The region's extent varies depending on context. The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the Western half of the ancient Mediterranean ...
and Western Central North America, respectively. These heat extremes have already been shown to cause 3–4% declines in crop yield across the affected regions: yet, concerningly, climate models overestimate the effects of such historic events in North America and underestimate them elsewhere, simulating effectively no net yield loss.


Labour and economic effects

As extreme weather events become more common and more intense, floods and droughts can destroy crops and eliminate food supply, while disrupting agricultural activities and rendering workers jobless. With more costs to the farmer, some will no longer find it financially feasible to farm: i.e. some farmers may choose to permanently leave drought-affected areas.
Agriculture Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...
employs the majority of the population in most low-income countries and increased costs can result in worker layoffs or pay cuts. Other farmers will respond by raising their
food prices Food prices refer to the average price level for food across countries, regions and on a global scale. Food prices affect producers and consumers of food. Price levels depend on the food production process, including food marketing and food di ...
; a cost that is directly passed on to the consumer and affects the affordability of food. Some farms do not sell their produce but instead feed a family or community; without that food, people will not have enough to eat. This results in decreased production, increased food prices, and potential starvation in parts of the world. The agriculture industry in
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
makes up 52% of their employment and the
Canadian Prairies The Canadian Prairies (usually referred to as simply the Prairies in Canada) is a region in Western Canada. It includes the Canadian portion of the Great Plains and the Prairie provinces, namely Alberta, Saskatchewan, and Manitoba. These provin ...
supply 51% of Canadian agriculture; any changes in the production of food crops from these areas could have profound effects on the
economy An economy is an area of the Production (economics), production, Distribution (economics), distribution and trade, as well as Consumption (economics), consumption of Goods (economics), goods and Service (economics), services. In general, it is ...
. Notably, one estimate suggests that a warming of relative to late 20th century (i.e. closer to when compared to preindustrial temperatures – a level associated with the SSP5-8.5 scenario) would cause labour capacity in
Sub-Saharan Africa Sub-Saharan Africa is the area and regions of the continent of Africa that lie south of the Sahara. These include Central Africa, East Africa, Southern Africa, and West Africa. Geopolitically, in addition to the list of sovereign states and ...
and
Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...
to decline by 30 to 50%, as the number of days when outdoor workers experience heat stress increases: up to 250 days the worst-affected parts of these two continents and of Central and
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
. This could then increase crop prices by around 5%. Similarly,
North China Plain The North China Plain () is a large-scale downfaulted rift basin formed in the late Paleogene and Neogene and then modified by the deposits of the Yellow River. It is the largest alluvial plain of China. The plain is bordered to the north by th ...
is also expected to be highly affected, in part due to the region's extensive
irrigation Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has bee ...
networks resulting in unusually moist air. In scenarios without aggressive action to stop climate change, some heatwaves could become extreme enough to cause mass mortality in outdoor labourers, although they will remain relatively uncommon (up to around once per decade starting from 2l00 under the most extreme scenario). Further, the role of climate change in undernutrition and micronutrient deficiencies can be calculated as the loss of "years of full health".One estimate presented in 2016 suggests that under the scenario of strong warming and low adaptation due to high global conflict and rivalry, such losses may take up 0.4% of the global
GDP Gross domestic product (GDP) is a monetary measure of the total market value of all the final goods and services produced and rendered in a specific time period by a country or countries. GDP is often used to measure the economic performance o ...
and 4% of the GDP in India and the
South Asia South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...
n region by the year 2100.


Long-term predictions (beyond 2050)

There are fewer projections looking beyond 2050. In general, even as climate change would cause increasingly severe effects on food production, most scientists do not anticipate it to result in mass human mortality within this century. This is in part because the studies also anticipate at least some continuation of the ongoing agricultural improvements, yet also because of
agricultural expansion Agricultural expansion describes the growth of agricultural land ( arable land, pastures, etc.) especially in the 20th and 21st centuries. The agricultural expansion is often explained as a direct consequence of the global increase in food and e ...
. For instance, a 2013 paper estimated that if the high warming of RCP 8.5 scenario was not alleviated by fertilization effect, it would reduce aggregate yields by 17% by the year 2050: yet, it anticipated that this would be mostly offset through an 11% increase in cropland area. Similarly, one of the assumptions of
Shared Socioeconomic Pathways Shared Socioeconomic Pathways (SSPs) are climate change scenarios of projected socioeconomic global changes up to 2100 as defined in the IPCC Sixth Assessment Report on climate change in 2021. They are used to derive greenhouse gas emissions sc ...
is a significant increase in land allocated to agriculture (and a corresponding decrease in
forest A forest is an ecosystem characterized by a dense ecological community, community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, ...
and "other natural land" area) in every pathway besides the SSP1 (officially subtitled "
Sustainability Sustainability is a social goal for people to co-exist on Earth over a long period of time. Definitions of this term are disputed and have varied with literature, context, and time. Sustainability usually has three dimensions (or pillars): env ...
" or "Taking the Green Road"), where the inverse occurs – and which has both the lowest level of future warming and the lowest projected
population growth Population growth is the increase in the number of people in a population or dispersed group. The World population, global population has grown from 1 billion in 1800 to 8.2 billion in 2025. Actual global human population growth amounts to aroun ...
.


Regional effects


Africa


Asia

For
East East is one of the four cardinal directions or points of the compass. It is the opposite direction from west and is the direction from which the Sun rises on the Earth. Etymology As in other languages, the word is formed from the fact that ea ...
and
Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...
, an estimate in 2007 stated that
crop yield In agriculture, the yield is a measurement of the amount of a crop grown, or product such as wool, meat or milk produced, per unit area of land. The seed ratio is another way of calculating yields. Innovations, such as the use of fertilizer, the ...
s could increase up to 20% by the mid-21st century. In Central and South Asia, projections suggested that yields might decrease by up to 30%, over the same time period. Taken together, the risk of hunger was projected to remain very high in several developing countries. Different Asian Countries have various effects from climate change.
China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
, for example, benefits from a temperature increase scenario accompanying with carbon fertilization and leading to a 3% gain of US$18 billion per year; however,
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
will face two thirds of the continent's aggregate losses on agriculture because its high corp net revenue suffers from the high spring temperature. In the
Indo-Gangetic plain The Indo-Gangetic Plain, also known as the Northern Plain or North Indian River Plain, is a fertile plain spanning across the northern and north-eastern part of the Indian subcontinent. It encompasses North India, northern and East India, easte ...
of India, heat stress and water availability are predicted to have significant negative effects on yield of wheat. Direct effects of increased mean and maximum temperatures is predicted to reduce wheat yields by up to 10%. The effect of reduced availability of water for irrigation is more significant, running at yield losses up to 35%. Due to climate change,
livestock Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...
production will be decreased in
Bangladesh Bangladesh, officially the People's Republic of Bangladesh, is a country in South Asia. It is the List of countries and dependencies by population, eighth-most populous country in the world and among the List of countries and dependencies by ...
by diseases, scarcity of forage, heat stress and breeding strategies.


Australia and New Zealand

Without further adaptation to climate change, projected effects would likely be substantial. By 2030, production from agriculture and
forestry Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests and woodlands for associated resources for human and Natural environment, environmental benefits. Forestry is practiced in plantations and ...
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.


Europe

For
Southern Europe Southern Europe is also known as Mediterranean Europe, as its geography is marked by the Mediterranean Sea. Definitions of southern Europe include some or all of these countries and regions: Albania, Andorra, Bosnia and Herzegovina, Bulgaria, C ...
, it was predicted in 2007 that climate change would reduce crop productivity. In Central and
Eastern Europe Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural and socio-economic connotations. Its eastern boundary is marked by the Ural Mountain ...
, forest productivity was expected to decline. In
Northern Europe The northern region of Europe has several definitions. A restrictive definition may describe northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other ge ...
, the initial effect of climate change was projected to increase crop yields. The 2019
European Environment Agency The European Environment Agency (EEA) is the agency of the European Union (EU) which provides independent information on the environment. Definition The European Environment Agency (EEA) is the agency of the European Union (EU) which provides ...
report "Climate change adaptation in the agricultural sector in Europe" again confirmed this. According to this 2019 report, projections indicate that yields of non-irrigated crops like wheat, corn and sugar beet would decrease in southern Europe by up to 50% by 2050 (under a high-end emission scenario). This could result in a substantial decrease in farm income by that date. Also farmland values are projected to decrease in parts of southern Europe by more than 80% by 2100, which could result in land abandonment. The trade patterns are also said to be affected, in turn affecting agricultural income. Also, increased food demand worldwide could exert pressure on food prices in the coming decades. In
Ukraine Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...
, where temperatures are increasing throughout the year and precipitation is predicted to increase,
winter wheat Winter wheat (usually ''Common wheat, Triticum aestivum'') are strains of wheat that are planted in the autumn to germinate and develop into young plants that remain in the vegetative phase during the winter and resume growth in early spring. C ...
yields (wheat sown in winter) could increase by 20–40% in the north and northwestern regions by 2050, as compared to 2010.


Latin America

The major agricultural products of
Latin America Latin America is the cultural region of the Americas where Romance languages are predominantly spoken, primarily Spanish language, Spanish and Portuguese language, Portuguese. Latin America is defined according to cultural identity, not geogr ...
include
livestock Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...
and grains; such as maize, wheat, soybeans, and rice. Increased temperatures and altered hydrological cycles are predicted to translate to shorter growing seasons, overall reduced biomass production, and lower grain yields.
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
,
Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
and
Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...
alone contribute 70-90% of the total agricultural production in Latin America. In these and other dry regions, maize production is expected to decrease. A study summarising a number of impact studies of climate change on agriculture in Latin America indicated that wheat is expected to decrease in Brazil, Argentina and
Uruguay Uruguay, officially the Oriental Republic of Uruguay, is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast, while bordering the Río de la Plata to the south and the A ...
. Livestock, which is the main agricultural product for parts of Argentina, Uruguay, southern Brazil,
Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...
, and
Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...
is likely to be reduced. Variability in the degree of production decrease among different regions of Latin America is likely. For example, one 2003 study that estimated future maize production in Latin America predicted that by 2055 maize in eastern Brazil will have moderate changes while Venezuela is expected to have drastic decreases. Increased rainfall variability has been one of the most devastating consequences of climate change in Central America and Mexico. From 2009 to 2019, the region saw years of heavy rainfall in between years of below average rainfall. The spring rains of May and June have been particularly erratic, posing issues for farmers plant their maize crops at the onset of the spring rains. Most subsistence farmers in the region have no irrigation and thus depend on the rains for their crops to grow. In Mexico, only 21% of farms are irrigated, leaving the remaining 79% dependent on rainfall. Suggested potential adaptation strategies to mitigate the effects of global warming on agriculture in Latin America include using plant breeding technologies and installing irrigation infrastructure.


North America

Droughts are becoming more frequent and intense in arid and semiarid western North America as temperatures have been rising, advancing the timing and magnitude of spring snow melt floods and reducing river flow volume in summer. Direct effects of climate change include increased heat and water stress, altered crop
phenology Phenology is the study of periodic events in biological life cycles and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors (such as elevation). Examples include the date of emergence of leav ...
, and disrupted symbiotic interactions. These effects may be exacerbated by climate changes in river flow, and the combined effects are likely to reduce the abundance of native trees in favour of non-native
herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...
and drought-tolerant competitors, reduce the habitat quality for many native animals, and slow litter decomposition and
nutrient A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...
cycling. Climate change effects on human water demand and irrigation may intensify these effects. In
Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
, notable increases are predicted for spring-sown wheat.


Adaptation

Climate change adaptation measures may reduce the risk of negative effects on agriculture from climate change. Adaptation can occur through changes in management practices, agricultural innovation, institutional changes, and climate-smart agriculture. To create a
sustainable food system A sustainable food system is a type of food system that provides healthy diet, healthy food to people and creates sustainable environmental, economic, and social systems that surround food. Sustainable food systems start with the development of Su ...
, these measures are considered as essential as changes needed to reduce global warming in general. Agricultural innovation is essential to addressing the potential issues of climate change. This includes better management of soil, water-saving technology, matching crops to environments, introducing different crop varieties, crop rotations, appropriate
fertilization Fertilisation or fertilization (see American and British English spelling differences#-ise, -ize (-isation, -ization), spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give ...
use, and supporting community-based adaptation strategies. On a government and global level, research and investments into
agricultural productivity Agricultural productivity is measured as the ratio of Agriculture, agricultural outputs to inputs. While individual products are usually measured by weight, which is known as crop yield, varying products make measuring overall agricultural out ...
and
infrastructure Infrastructure is the set of facilities and systems that serve a country, city, or other area, and encompasses the services and facilities necessary for its economy, households and firms to function. Infrastructure is composed of public and pri ...
must be done to get a better picture of the issues involved and the best methods to address them. Government policies and programs must provide environmentally sensitive government
subsidies A subsidy, subvention or government incentive is a type of government expenditure for individuals and households, as well as businesses with the aim of stabilizing the economy. It ensures that individuals and households are viable by having acce ...
, educational campaigns, and economic incentives as well as funds,
insurance Insurance is a means of protection from financial loss in which, in exchange for a fee, a party agrees to compensate another party in the event of a certain loss, damage, or injury. It is a form of risk management, primarily used to protect ...
, and safety nets for vulnerable populations. In addition, providing early warning systems, and accurate
weather forecasts Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloud cover, cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmo ...
to poor or remote areas will allow for better preparation. A 2023 study published in Nature Food highlights that climate change poses severe risks to global food security, and emphasizes that urgent adaptation and mitigation strategies are needed to protect vulnerable populations and food systems worldwide.


Greenhouse gas emissions from agriculture


See also

* 2022 food crises *
Agroecology Agroecology is an academic discipline that studies ecological processes applied to agricultural production systems. Bringing ecological principles to bear can suggest new management approaches in agroecosystems. The term can refer to a science, ...
* Climate change and invasive species * Climate change and meat production *
Climate resilience Climate resilience is a concept to describe how well people or ecosystems are prepared to bounce back from certain climate hazard events. The formal definition of the term is the "capacity of social, economic and ecosystems to cope with a hazardou ...
* Climate-smart agriculture *
Effects of climate change Effects of climate change are well documented and growing for Earth's natural environment and human societies. Changes to the climate system include an Instrumental temperature record, overall warming trend, Effects of climate change on the ...
* Effects of climate change on fisheries * Environmental issues with agriculture *
Multiple breadbasket failure A multiple breadbasket failure is the simultaneous disruption of Grain, grain production in several major Agriculture, agricultural regions globally, primarily due to acute climate events. This phenomenon has gained increasing attention in Climate ...
*
Special Report on Climate Change and Land The United Nations' Intergovernmental Panel on Climate Change's (IPCC) Special Report on Climate Change and Land (SRCCL), also known as the "Special Report on climate change, desertification, land degradation, sustainable land management, food se ...
(2019 IPCC report)


References


External links


Climate change
(
Food and Agriculture Organization The Food and Agriculture Organization of the United Nations; . (FAO) is a specialized agency of the United Nations that leads international efforts to defeat hunger and improve nutrition and food security. Its Latin motto, , translates ...
of the United Nations)
Climate adaptation & mitigation
(CGIAR) {{agriculture footer Effects of climate change