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Effects of climate change on agriculture | HearLore
— Ch. 1 · Observed Weather Impacts —
Effects of climate change on agriculture.
~8 min read · Ch. 1 of 7
The 2003 European heatwave caused 13 billion euros in uninsured agricultural losses. This event marked a turning point where extreme weather began to visibly disrupt food production across the continent. Farmers in Southern Africa faced acute food insecurity after climate change intensified drought conditions in 2007. In West Africa, climate-induced intensification of extreme weather decreased millet yields by 10, 20% and sorghum yields by 5, 15%. These specific regional failures demonstrated that historical data could no longer be relied upon for future planning.
Between 1964 and 1990, heat extremes in Europe resulted in crop losses of just 2.2%. By the period from 1991 to 2015, those same losses had tripled to 7.3%. The summer of 2018 brought heat waves linked to climate change that greatly reduced average yields globally, with Europe suffering particularly hard. During August of that year, multiple crop failures drove up global food prices. Floods also played a destructive role, such as the May 2019 floods in the Midwestern United States which shortened the corn planting season. Projected yield dropped from 15 billion bushels to 14.2 billion bushels due to these water events.
In China, research published in 2023 found that extreme rainfall cost the country about 8% of its rice output over two decades. This loss was comparable to damage caused by extreme heat during the same period. The 2021 European floods caused severe damage to Belgium's agricultural sector, including long-term soil erosion. These examples show how weather patterns have shifted from manageable anomalies into recurring threats that directly reduce harvest volumes.
Temperature And Livestock Stress
Rising temperatures create direct harm to livestock through heat stress and the spread of vector-borne diseases. Warmer winters allow pests like the Mountain Pine Beetle to survive where cold once killed them off. In British Columbia, Canada, this beetle epidemic killed millions of pine trees because winters were not cold enough to slow or kill growing larvae. Similar shifts are predicted for potato tuber moths and Colorado potato beetles spreading into areas currently too cold for them.
The fall armyworm, Spodoptera frugiperda, is a highly invasive plant pest causing massive damage to crops, especially maize. It has recently spread to countries in sub-Saharan Africa, a movement linked to climate change. Locust swarms also cause more damage as conditions change; the 2019, 2022 locust infestation focused on East Africa was considered the worst of its kind in many decades. Insect species that previously had only two breeding cycles per year could gain an additional cycle if warm growing seasons extend, causing population booms.
Agricultural productivity growth will likely improve food security for hundreds of millions of people by 2050, yet risks remain high. Between 1961 and 2021, global agricultural productivity could have been 21% greater than it actually was without climate change interference. This loss affects both crop yields and livestock health. Warmer temperatures contribute to the spread and growth of pests and diseases that threaten animal feed shortfalls. The increased atmospheric level from human activities causes a fertilization effect that offsets some detrimental impacts but comes at the expense of lower essential micronutrients.
Nutritional Quality Decline
Elevated carbon dioxide levels reduce essential protein and mineral content in major staple crops. Wheat is expected to have less protein and fewer minerals like zinc and iron under future atmospheric conditions. A 2014 meta-analysis showed that crops exposed to elevated carbon dioxide levels at various latitudes have lower density of several minerals such as magnesium, iron, zinc, and potassium. Studies using Free-Air Concentration Enrichment confirmed these findings, showing decreases in B vitamins in rice as well.
Doubling carbon dioxide levels results in an 8% decline on average in the concentration of minerals within plant tissues. Some two billion people live in countries where citizens receive more than 60 percent 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. Populations in low- and middle-income countries are particularly at risk, having staple crops like rice and wheat as primary sources of daily protein, iron, and zinc.
The increase in carbon is mostly attributed to carbohydrates without a structural role in plants, specifically starch and simple sugars. The decrease in nitrogen translates directly into a decrease in protein content. These nutritional declines have severe consequences for public health worldwide, especially in areas traditionally consuming plant-based diets. A 2022 narrative review highlighted that climate change not only impacts food quantity but also reduces the nutritional quality of crops.
Pests And Pathogen Spread
Warmer climates accelerate breeding cycles of insects and allow plant diseases to migrate into previously unaffected zones. Historically, cold temperatures at night and in winter months killed off bacteria and fungi. Warmer winters promote fungal plant diseases like wheat rusts and soybean rust to travel northward. Insect pollinators and pests face different fates; around 9% of agricultural production depends on insect pollination, yet some wild bumblebees are vulnerable to recent warming.
Bacteria like Salmonella and fungi producing mycotoxins grow faster as the climate warms. Their growth has negative effects on food safety, food loss, and prices. Currently, pathogens result in losses of 10, 16% of the global harvest, a level likely to rise as plants face increasing exposure to pests and pathogens. Research shows climate change may alter developmental stages of plant pathogens affecting crops, such as Dickeya associated with potato blackleg disease.
Soybean rust is a vicious pathogen capable of killing entire fields within days, devastating farmers and costing billions in losses. Aphids act as vectors for many potato viruses and will spread further due to increased temperatures. Climate change alters pathogen and host interactions, specifically infection rates and host resistance. This increases crop losses due to diseases spreading as hosts migrate to areas with more favorable conditions.
Water Scarcity And Soil Loss
Glacial retreat threatens irrigation reliability while extreme weather events accelerate soil erosion. Since 1850, observed glacier mass loss continues, depleting ice and reducing runoff used for agriculture. In Asia, global warming reduces the ice mass of high mountains by about 29, 43%. Approximately 2.4 billion people live in the drainage basin of Himalayan rivers. The river Ganges provides water for drinking and farming for over 500 million people in India alone.
In the Indus River watershed, mountain water resources contribute up to 60% of irrigation outside monsoon seasons. Agriculture in this region becomes more reliant on monsoons than ever before. Sea level rise also causes agricultural land loss, particularly in South East Asia. Low-lying areas like Bangladesh, India, and Vietnam face major rice crop losses if sea levels rise as expected by the end of the century. A one-meter rise covers several square kilometers of rice paddies in Vietnam.
Saltwater intrusion into freshwater wells occurs when concentration exceeds 2, 3%, rendering wells unusable. Areas along an estimated 15% of the US coastline already have most local groundwater below sea level. Erosion and soil degradation are more likely due to heavy rainfall and extreme weather. Increased erosion can cause losses of up to 22% of soil carbon in 50 years. Warmer conditions accelerate decomposition of soil organic matter, reducing the soil's ability to retain nutrients.
Global Food Security Projections
Future models predict increased hunger risks for millions of people by 2050 due to synchronized crop failures and price volatility. The IPCC Sixth Assessment Report suggested that by 2050, the number of people at risk of hunger will increase under all scenarios by between 8 and 80 million people. Nearly all of them reside in Sub-Saharan Africa, South Asia, and Central America. In 2021, 720 million to 811 million people were considered undernourished globally.
A baseline projected level of socioeconomic development would reduce this number to 122 million globally by 2050 even as population grows to reach 9.2 billion. Climate change could add an additional 8 to 80 million people at risk of hunger depending on warming intensity and adaptation measures. 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 according to a 2016 estimate.
Synchronized climate events have already caused up to 20% yield losses historically. Analysis suggests there is a 4.5-fold increase in probability of breadbasket failures by 2030 under high-emission scenarios. This corresponds to reaching thresholds where simultaneous heat extremes strike multiple producer regions. A ban on export of staple crops from Russia, Thailand, and the United States alone places around 200 million people at risk of starvation.
Economic And Labor Consequences
Heat stress is projected to significantly reduce outdoor labor capacity, leading to economic losses and potential mass mortality among farm workers. One estimate suggests that a warming of relative to late 20th century would cause labor capacity in Sub-Saharan Africa and Southeast Asia to decline by 30 to 50%. The number of days when outdoor workers experience heat stress increases to up to 250 days in worst-affected parts of these continents and Central and South America.
Agriculture employs the majority of the population in most low-income countries. Increased costs can result in worker layoffs or pay cuts. Some farmers may choose to permanently leave drought-affected areas if farming becomes financially unfeasible. Others respond by raising food prices, directly passed on to consumers affecting affordability. In India, agriculture makes up 52% of employment, while Canadian Prairies supply 51% of national agriculture.
One estimate presented in 2016 suggests that under strong warming scenarios, such losses may take up 0.4% of global GDP and 4% of GDP in India and the South Asian region by 2100. Global warming intensifies existing harms like soil loss and pollution by reducing crop yields. This creates a vicious feedback loop making sustainable food production increasingly difficult unless farming systems become more resilient.
What were the financial losses from the 2003 European heatwave on agriculture?
The 2003 European heatwave caused 13 billion euros in uninsured agricultural losses. This event marked a turning point where extreme weather began to visibly disrupt food production across the continent.
How did climate change affect crop yields in West Africa during 2007?
Climate-induced intensification of extreme weather decreased millet yields by 10, 20% and sorghum yields by 5, 15%. These specific regional failures demonstrated that historical data could no longer be relied upon for future planning.
What impact does elevated carbon dioxide have on mineral content in staple crops like wheat and rice?
Doubling carbon dioxide levels results in an 8% decline on average in the concentration of minerals within plant tissues. A 2014 meta-analysis showed that crops exposed to elevated carbon dioxide levels at various latitudes have lower density of several minerals such as magnesium, iron, zinc, and potassium.
How many people are projected to be at risk of hunger globally by 2050 due to climate change scenarios?
The IPCC Sixth Assessment Report suggested that by 2050, the number of people at risk of hunger will increase under all scenarios by between 8 and 80 million people. Nearly all of them reside in Sub-Saharan Africa, South Asia, and Central America.
Which regions face major rice crop losses from sea level rise and saltwater intrusion by the end of the century?
Low-lying areas like Bangladesh, India, and Vietnam face major rice crop losses if sea levels rise as expected by the end of the century. Saltwater intrusion into freshwater wells occurs when concentration exceeds 2, 3%, rendering wells unusable.