Agriculture and the Environment

Modern, large-scale agriculture has led to increased GHG emissions, primarily resulting from high energy inputs, land clearing, soil degradation, and overgrazing by livestock. The massive conversion of forests into farms has reduced the land’s capacity to absorb more carbon than it emits, also called a carbon sink. As a result, more GHGs are emitted into the atmosphere, contributing to global warming and climate change.

Background

There is a consensus among scientists that the mean temperature of Earth will increase by approximately 2.0° to 11.5° Celsius in the twenty-first century, with higher degrees of change accounting for potential changes in vegetation cover. The resulting elevated temperatures,even at the lower end of the estimates, will have significant effects on Earth’s biosphere, including human life. Many factors are associated with this predicted temperature rise, but agriculture is among the major contributors.

Direct Impacts of Agriculture on Climate Change

Agricultural activity is a significant source of greenhouse gasses (GHGs). GHG levels are affected by land clearing, high energy inputs, soil degradation, and intensive animal husbandry. Agriculture contributes to 25 percent of the world’s carbon dioxide (CO₂) emissions, 60 percent of methane gas emissions, and 80 percent of nitrous oxide emissions. Agriculture’s high energy input results primarily from manufacturing chemical fertilizers, herbicides, pesticides, operating farm machinery, irrigating farmland using pumps and other machines, and transporting products over long distances. Collectively, these activities account for more than 90 percent of the total energy expenditure in agriculture.

Burning fossil fuels releases CO₂ into the atmosphere. The bltace2f25b1384ebbchas increased from 277 parts per million around the beginning of the Industrial Revolution in the mid-eighteenth century to nearly 420 parts per million by 2023. Industrialized agriculture is believed to have contributed to 25 percent of that increase.

Overuse of fertilizers, in addition to energy inputs in fertilizer manufacturing, contributes significantly to climate change. More than half of all synthetic fertilizers applied to the soil end up in local waterways or the atmosphere. A portion of the excess nitrogen fertilizers in the soil is converted into nitrous oxide, which is 296 times more potent than CO₂ in trapping heat and has a long atmospheric lifetime of 114 years. Each year, nitrous oxide emissions alone account for the equivalent of 1.9 billion metric tons of CO₂ emissions.

The second greatest GHG emission by agriculture is methane, released in small amounts by rice paddies and in much larger amounts by livestock. As the demand for meat increases, more livestock are raised and are fed higher-protein diets. Both the number of livestock and their protein-rich diets increase the amount of methane they emit. Methane gas is fourteen times more potent than CO₂ in trapping heat. Its concentration has almost tripled since the Industrial Revolution, from around 600 parts per billion to around 1,900 parts per billion in 2022.

Indirect Impacts of Agriculture on Climate Change

Agriculture also contributes indirectly to climate change. Clearing trees and other natural stands to make land suitable for agricultural uses removes important carbon sinks, so less carbon is returned to the terrestrial biosphere, and more CO₂ finds its way into the atmosphere, where it contributes to climate change.

The effect of land clearing on climate change is evident from the consequences of the destruction of tropical rainforests. Large areas in Brazil have been cleared to facilitate soybean production, which disrupts the local water cycle and alters Brazil’s climate. In rainforests, water circulates as a result of evaporation, which greatly increases humidity. Natural tree stands act to buffer extremes of heat, cold, and drought. When the trees are removed, the buffer disappears. Moreover, the amount of water vapor in the air decreases, causing shifts in rainfall patterns, moisture levels, air temperature, and weather patterns generally.

The conversion of forests into agricultural lands has significantly altered Earth’s vegetation cover. Such changes in the land surface affect Earth’s albedo—that is, the proportion of incident radiation reflected by the planet’s surface. Changes in the albedo can affect the surface energy budget, which affects local, regional, and global climates. Changes in vegetation also produce changes in the global atmospheric concentration of CO₂. Agricultural landscape ranks among the lowest in carbon sequestration. Thus, as more land is devoted to agricultural uses, more of Earth’s carbon is converted to CO₂ and emitted to the atmosphere, contributing to global warming.

Effects of Climate Change on Agriculture

Potential climate changes associated with elevated GHGs and an altered surface energy budget include an increased incidence of heat waves, severe storms, and floods, as well as elevated sea levels. Some 30 percent of the agricultural lands worldwide could be affected by these changes. Global warming alone is projected to have considerable effects on agriculture. A warming of 2° Celsius or more could reduce global food supplies and aggravate world hunger. The impact on crop yields will vary considerably across different agricultural regions. Warm regions, such as tropics and subtropics, will be threatened by climate change, while cooler regions, mainly in temperate or higher latitudes, may benefit from warming.

Global climate change may also have significant effects on livestock systems. First, the productivity and quality of rangelands may be adversely affected. This in turn will affect the quality and productivity of livestock. Second, higher grain prices resulting from the disruption of crop production will lead to higher costs for livestock products. Third, increased severity and frequency of storms may intensify soil erosion and decrease the productivity of rangelands. Fourth, global warming could result in changes in the distribution and severity of livestock diseases and parasites, which may threaten the health of animals, especially those in intensively managed livestock systems.

Possible Solutions

Unlike any other industrial GHG emitters, agriculture has the potential to change from being one of the largest GHG sources to being a net carbon sink, reversing its role in climate change. Several practical measures can be taken to mitigate the climate change caused by intensive agriculture. These include the reduced and more efficient use of chemical fertilizers, protection of soil, improvement of paddy rice production, and reduction of demand for meat.

Precision farming can reduce the need for chemical fertilizers. In precision farming, fertilizers and other agrochemicals are applied based on crops’ needs, in precise amounts, and on a carefully managed schedule. The reduced application of these chemicals not only cuts GHG emissions but also alleviates other environmental problems, such as water pollution and eutrophication of waterways.

As a result of intensive farming, agricultural soils have some of the lowest carbon contents of all land types. If these soils can be modified to absorb more of Earth’s carbon, the result will be a net reduction in atmospheric carbon. Low soil carbon content can be reversed through a number of measures, including planting cover crops, fallowing, and engaging in conservation tillage. These practices will increase the amount of organic matter (and thus the carbon content) in the soil. They will also reduce soil erosion and surface runoff, thereby reducing the need for chemical fertilizers. Collectively, these measures can turn agricultural soils into carbon sinks, changing the nature of their impact on climate change.

To reduce methane emissions from rice production, better cultivation techniques will need to be adapted. For example, rather than continuously flooding rice paddies, farmers could supply water to the paddies only when it is needed during the growing season. Such measures could reduce methane emissions from rice fields significantly.

Livestock raising is the second largest source of GHGs in agriculture. The most efficient way to cut methane emissions due to livestock is simply to reduce the number of farm animals. As an ever-increasing demand for meat and dairy products drives increasing animal husbandry, one effective approach to cut methane emissions is to reduce the demand for meat, especially in developed countries where consumers have tremendous buying power. Reduced meat and dairy consumption may greatly curb methane emissions.

In 2020, the World Bank Group (WBG) focused 52 percent of its agricultural financing on climate adaptation and mitigation. The WBG’s Climate Change Action Plan 2021-2025 is focused on improving agricultural practices globally to be more climate friendly and funding agriculture programs that align with climate conscious goals and develop technology concerning climate friendly agriculture.

Context

Agriculture and climate change are interlocked processes with complex interactions. Climate changes, especially shifts in precipitation and temperature, are widely believed to have significant effects on agriculture because these two factors determine the carrying capacity of any ecosystem. Modern agriculture is a major contributing factor to global warming, as altered land cover and the emission of CO₂, methane gas, and nitrous oxide from intensive farming increase the GHG content of the atmosphere. According to Science Direct, in 2022, food-system emissions contributed as much as 34 percent of total global GHG emissions. Agricultural methane from livestock greatly contributed to this percentage and was a significant driver of climate change. However, it remains possible to transform industrialized agriculture, using techniques that could render it more sustainable and mitigate its effects upon global and local climates.

Key Concepts

• carbon cycle: processes through which carbon atoms circulate among Earth’s atmosphere, terrestrial biosphere, oceans, and sediments—including fossil fuels
• climate change: a statistically significant variation in either the mean state of the climate or its variability
• energy-intensive agriculture: a method of farming that involves working on a large scale, utilizing significant resources, energy, and mechanization; often also referred to as industrialized agriculture
• greenhouse effect: phenomenon in which certain gasses in a planet’s atmosphere trap heat that would otherwise escape into outer space, thereby increasing the planet’s surface temperature

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