Effects of climate change on agriculture

Rising temperatures and changing weather patterns often result in lower crop yields due to water scarcity caused by drought, heat waves and flooding.

[17][18]Agriculture is sensitive to weather, and major events like heatwaves or droughts or heavy rains (also known as low and high precipitation extremes) can cause substantial losses.

[30] The current prediction is that temperatures will increase and precipitation will decrease in arid and semi-arid regions (Middle East, Africa, Australia, Southwest United States, and Southern Europe).

[32][33] 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 pollinators, threatening their reproductive success.

[39]: 747  Much like how climate change is expected to increase overall thermal comfort for humans living in the colder regions of the world,[40] livestock in those places would also benefit from warmer winters.

[41] Across the entire world, however, increasing summertime temperatures as well as more frequent and intense heatwaves will have clearly negative effects, substantially elevating the risk of livestock suffering from heat stress.

Under the climate change scenario of highest emissions and greatest warming, SSP5-8.5, "cattle,sheep, goats, pigs and poultry in the low latitudes will face 72–136 additional days per year of extreme stress from high heat and humidity".

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.

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.

[48] Droughts disturb terrestrial precipitation, evaporation and soil moisture,[49][50] and these effects can be aggravated by population growth and urban expansion spurring on increased demand for water.

[51] The ultimate outcome is water scarcity, which results in crop failures and the loss of pasture grazing land for livestock,[52] exacerbating pre-existing poverty in developing countries and leading to malnutrition and potentially famine.

A 2014 meta-analysis has shown that crops and wild plants exposed to elevated carbon dioxide levels at various latitudes have lower density of several minerals such as magnesium, iron, zinc, and potassium.

[101] Erosion, submergence of shorelines, salinity of the water table due to the increased sea levels, could mainly affect agriculture through inundation of low-lying lands.

Combined with higher temperatures, these conditions could favour the development of fungal diseases, such as late blight,[124][109] or bacterial infections such as Ralstonia solanacearum, which may also be able to spread more easily through flash flooding.

[126] 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.

[128] 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.

[128] Even in developed countries such as Australia, extreme weather associated with climate change has been found to cause a wide range of cascading spillovers through supply chain disruption, in addition to its primary effect on fruit, vegetable, and livestock sectors and the rural communities reliant on them.

Further, agricultural expansion 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 scenarios consistent with the Paris Agreement.

For instance, even by 2050, some agricultural areas of Australia, Brazil, South Africa, Southeast China, Southern Europe and the United States would suffer production losses of mostly maize and soybeans exceeding 25%.

Studies in Iran surrounding changes in temperature and rainfall are representative for several different parts of the world since there exists a wide range of climatic conditions.

A paper published in the year 2022 found that under the highest-warming SSP5-8.5 scenario, changes in temperature and soil moisture would reduce the aggregate yields of millet, sorghum, maize and soybeans by between 9% and 32%, depending on the model.

[40][172] This causes both mass animal mortality during heatwaves, and the sublethal impacts, such as lower quantity of quality of products like milk, greater vulnerability to conditions like lameness or even impaired reproduction.

[180] 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 and the Middle East, as well as parts of sub-Saharan Africa and Central America) would experience very rapid shift in Holdridge life zones (HLZ) and associated weather, while also being low in social resilience.

[182] This corresponds to reaching 1.5 °C (2.7 °F) and 2 °C (3.6 °F) 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.

[7] 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.

[5]: 717 : 725 Similarly, North China Plain is also expected to be highly affected, in part due to the region's extensive irrigation networks resulting in unusually moist air.

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.

For instance, a 2013 paper estimated that if the high warming of RCP 8.5 scenario was not alleviated by CO2 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.

[215] 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.

[212] 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.

The observed increase in extreme weather events in Europe , from 1964 to 2015. [ 19 ]
Soybean plants grow less and develop a smaller leaf area as they are exposed to temperatures beyond what they are historically used to. [ 20 ]
Climate-driven changes in crop yields at different latitudes, as projected by the US National Research Council in 2011. [ 28 ] : Figure 5.1
Maize will fail to reproduce at temperatures above 35 °C (95 °F) and soybean above 38.8 °C (101.8 °F). [ 29 ]
Increased intensity of global climate change causes even greater increases of thermal heat index in Jamaican farm animals. High thermal heat index is one of the more widely used indicators of heat stress. [ 38 ]
Future warming is expected to consistently increase the strength of heavy rainfall, yet it also consistently increases the amount of water plants lose through evotranspiration. [ 43 ] This effect is counteracted by the CO 2 fertilization effect, but at times not enough to avoid events like the 2020–2023 Horn of Africa drought . [ 3 ]
Observed glacier mass loss in the Hindu Kush Himalayas region since the 20th century. [ 54 ]
Top: the extent to which plant growth benefits from CO 2 in different areas (red=more positive impact.) Bottom: the impact on the main types of terrestrial biomes : evergreen broadleaf forests (EBFs), other forests (OF), short woody vegetation (SW), grasslands (GRA), croplands (CRO), plants with C4 carbon fixation and total. [ 63 ]
CO 2 fertilization (grey) results in substantially less severe cumulative effects on agricultural productivity compared to its absence (black), as estimated by the IPCC in 2007 . [ 80 ]
Average decrease of micronutrient density across a range of crops at elevated CO 2 concentrations, reconstructed from multiple studies through a meta-analysis . [ 86 ] The elevated concentration in this figure, 689 ppm, is over 50% greater than the current levels, yet it is expected to be approached under the "mid-range" climate change scenarios, and will be surpassed in the high-emission one. [ 87 ]
Some locations alongside the United States ' coast have over half of their freshwater wells below sea level, leaving them vulnerable to saltwater infiltration. [ 98 ]
Locust swarm near Satrokala , Madagascar in 2014.
A continental-scale research platform for long-term study of the effects of climate change, land-use change and invasive species on ecological systems (research site in Front Royal , Virginia, U.S.)
The already observed effects of climate change on the production of four major crops. [ 128 ]
Map of predicted climate change effects on agricultural yields between 2003 and 2080 (data from 2007). [ 80 ]
US National Research Council projections of climate change effects on the most important crops. [ 28 ] : Figure 5.1
Maize farming in Uganda is made more difficult due to heat waves and droughts worsened by climate change in Uganda .
A rice field suffering from the effects of drought in Binh Thuy District , Can Tho, Vietnam.
Wheat field in Hungary which had been affected by heavy rainfall in 2016.
Piezodorus guildinii , commonly known as red-banded stink bug, is a notable soybean pest which is expected to spread further and cause more damage in response to climate change.
A sorghum field at the shores of Lake Hayq in Ethiopia .
Response of six prominent potato varieties to drought conditions. [ 153 ]
Chardonnay grapes which had been damaged by heat from sunburn.
Map of countries considered most and least vulnerable to adverse impacts of climate change on their grazing livestock. [ 169 ]
Multi-faceted impacts of climate change on livestock. [ 41 ]
Projected changes in average food availability (represented as calorie consumption per capita ), population at risk of hunger and disability-adjusted life years under two Shared Socioeconomic Pathways : the baseline, SSP2, and SSP3, scenario of high global rivalry and conflict. The red and the orange lines show projections for SSP3 assuming high and low intensity of future emissions and the associated climate change. [ 173 ]
Areas of the globe where agriculture would become more difficult perhaps to the point of leaving the conditions historically suitable for it, under low-emission and high-emission scenarios, by 2100. [ 16 ]
Projections of crop yields for seven key crops in year 2100 and year 2500 under the second-highest warming scenario, RCP6.0 . (Research from 2021.) [ 180 ]
Certain countries around the world are particularly dependent on imports from specific exporters, leaving them the most vulnerable to crop failures in those countries. [ 181 ]
Climate change is expected to exacerbate heat stress over at the North China Plain , which is particularly vulnerable as widespread irrigation results in very moist air. There is a risk that agricultural labourers will be physically unable to work outdoors on hot summer days, particularly under the scenario of greatest emissions and warming. [ 186 ] [ 187 ]
In South Asia , the extent of cropland is expected to increase under most climate and socioeconomic scenarios, with some of the largest increases seen under high-warming scenarios. Low-warming scenarios are expected to see a decrease in area due to lower demand. [ 191 ] Similar trends are expected globally. [ 87 ]
Four political leaders sit on a stage facing an audience. They are answering questions at a food security and climate change session.
U.S. and African leaders meet at a Leaders Summit for Food Security and Climate change at the National Academy of Sciences in Washington, D.C. in 2014.
Climate smart agriculture in Machakos County , Kenya