The way we produce and consume food is inextricably connected to the earth’s changing climate.
Published: 10/08/18, Last updated: 2/28/24
Agriculture is a large contributor to greenhouse gas (GHG) emissions, which are the main driver of climate change. Scientists now predict — and it is already proving true — that there will be extreme shifts in typical weather patterns, like rainfall and temperature. It is also true that climate change poses numerous threats to our current food system, increasing farmers’ sense of risk and uncertainty. Shifting our food production system to more sustainable practices will help reduce agriculture’s role in climate change and also help make this industry become more resilient and adaptable to ever-changing conditions.
All along the food production and distribution chain, there are activities and products that come with varying degrees of associated greenhouse gas emissions. These emissions are known as a “carbon footprint, and the larger a carbon footprint, the larger the contribution to climate change.” (These days, the term “carbon footprint” is used as a catchall phrase for all the climate-change-causing greenhouse gases, not just carbon dioxide or other carbon derivatives.) 1 For example, some vegetables grown under ecologically sound agricultural principles may have a very low carbon footprint, whereas animals raised in factory farm conditions with large uncovered animal waste lagoons could have a high carbon footprint. 2
Agricultural activities, like manure treatment, use of farm equipment and application of synthetic fertilizers, have carbon footprints, too. In the US, agriculture accounts for nine percent of GHG emissions. Greenhouse gases, with carbon dioxide (CO2) being the most prominent, increase the planet’s ability to absorb and retain heat and thus contribute to climate change. Other GHGs involved in agriculture include: methane (CH4), produced by livestock; nitrous oxide (N2O), generally associated with synthetic fertilizer application; and carbon dioxide, produced by both the burning of fossil fuels and grassland loss/deforestation. 34
Not all food is produced in the same manner: some foods use more land, fertilizer (synthetic or organic) and energy and therefore have a greater potential to contribute to climate change — a greater carbon footprint.
A 2017 Natural Resources Defense Council (NRDC) report studied 197 foods, and analyzed their full lifecycle to approximate the climate warming potential of each food. 5 The report found that the food with the highest carbon footprint was conventionally raised beef. When one pound of conventional feedlot beef is produced, 26 pounds of carbon dioxide equivalent are emitted. (The term “carbon dioxide equivalent”, or CO2-eq, is used to “normalize” the different potencies of multiple greenhouse gases, including nitrous oxide, carbon dioxide and methane, among others, into standard units. Read more about this measurement here from Yale Climate Connections.)
Industrial meat and dairy production require significant quantities of animal feed, which is grown with synthetic fertilizers. The production of synthetic fertilizers contributes to overall CO2 emissions, while the use of them contributes to nitrous oxide emissions (N2O), another potent greenhouse gas (see Conventional Crop Production, below). 67 Animals that eat chew their cud (called ruminant animals) also emit significant quantities of methane when their bodies break down the feed in their gut (in a process called enteric fermentation). Methane is also produced by confined animal feeding operations (CAFOs), which process manure anaerobically (without oxygen) in manure lagoons and pits. 8 As a greenhouse gas, methane is 25 times more powerful than carbon dioxide.9
Globally, livestock contributes 14.5 percent of all greenhouse gas emissions that originate from human activity. 10 However, a better way to raise beef exists. More sustainable animal husbandry and welfare practices can use manure as a fertilizer — instead of synthetic fertilizers — to help the land capture and hold onto carbon. Rotating pasture-raised animals and crops can also help “sequester” carbon, improve soil and help prevent water pollution.
Farmers who raise cattle on pasture can use field, livestock and waste management programs that reduce emissions associated with cows’ manure. 11 The Food Climate Research Network reported on several studies which investigated the potential of pasture-raised cows’ ability to sequester carbon in soil. 12 The group found that the sequestration potential from the management of grazing could offset “20 to 60 percent of annual average emissions from the grazing ruminant sector.” Another recent report also showed that well-pastured beef could sequester a significant proportion of carbon produced on the farm, even suggesting that a negative carbon benefit is possible. 13 With smaller herd management of animals on pasture, manure is composted directly into the soil and becomes fertilizer for a healthy pasture, with less methane released, as well. 14
Efficiently mitigating livestock’s contribution to greenhouse gases is an important effort, but only one reason to produce beef more sustainably.
26 pounds
of carbon dioxide are emitted when one pound of feedlot beef is produced
Anaerobic manure digesters are sometimes promoted as a means by which confined animal feeding operations (CAFOs) can dispose of their animal waste in a manner that is more environmentally and climate friendly. Digesters use a combination of microbes, heat, water and agitation to process waste, producing methane gas that can be used for energy, liquid manure that can be used for fertilizer and solid manure that can be used for composting and cow bedding.
Despite federal and state financial investments for the new technology, there is growing skepticism about digesters. A 2016 report by Food and Water Watch details the ways in which digesters do not live up to their promise of cleaning waste and mitigating greenhouse gases — and instead serve as a subsidy to the CAFO industry, further entrenching the confinement model of food production. 15 According to Food and Water Watch, digesters do not capture all of the methane they produce, and in burning methane, produce GHG carbon dioxide and nitrous oxide, as well. 16
Synthetic nitrogen (N) fertilizers are produced from fossil fuels (like coal and natural gas) and are used extensively in conventional crop production. Globally, the use of synthetic fertilizers contribute to about 13 percent of agricultural GHG emissions. 17
While nitrogen fertilizers have improved yields worldwide, recent studies indicate that the increased use of nitrogen-based fertilizers over the last 50 years has increased the rates of nitrous oxide emissions exponentially, as compared with the rate of use of other fertilizers. 18 What this means is a large rise in atmospheric nitrous oxide — a greenhouse gas 300 times more potent than CO2.
As discussed above, conventional land use management practices for crop or animal production can act as a carbon source, while more sustainable practices can act as a carbon sink — sucking up and storing the carbon dioxide from the atmosphere.
A farming practice called “tilling,” turning over and breaking up the soil, can expose carbon that was locked in the soil and can facilitate erosion. This means that low-till or no-till farming is a more sustainable option. One of the larger carbon sources is the expansion of cropland, i.e. cutting down forests and eradicating grassland, for growing conventional animal feed and creating land for grazing livestock. This means that two thirds of available agricultural land worldwide is now used for animal production, which includes marginal land for grazing and other land used for feed crops. Some incentives, like rising crop prices, may make taking land out of conservation more attractive to farmers, in turn eliminating that carbon sink. 19
As farms and ranchland expand, concerns about deforestation mount. It is estimated that agriculture is responsible for 75 percent of global deforestation. 20 For example, when many trees are clear cut, this loss alters the water cycle in a specific climate: this can result in local climate change. Likewise, when forests are burned down for agricultural purposes, the burning trees release their sequestered carbon into the atmosphere, adding to greenhouse gas emissions: this can result in climate change locally and globally.
It is not only climate change that is of growing concern, but biodiversity loss, as well. Deforestation goes hand-in-hand with the loss of species within a given ecosystem. Broadly, biodiversity loss can cause disruptions in ecosystems, which in turn can produce a wide range of negative effects, including soil, water and air degradation. 21 Biodiversity loss can also cause declines in an ecosystem’s ability to cope with extreme weather events and other effects of climate change. According to the National Climate Assessment, biodiversity is directly impacted by climate change, from the timing of biological events (like plant growing patterns), to shifts in the range of certain species including their extinction. 22
If managed well, farms can use practices that act as “carbon sinks” to help take carbon dioxide out of the atmosphere and sequester it in the soil on the farm, helping to fight climate change. 23 24 The central methods of carbon farming include: using a seed drill to avoid tilling the soil and make it possible to plant seeds beneath the surface without disrupting the topsoil; covering the soil with organic mulch to prevent carbon losses; composting; rotating livestock on fields; and planting cover crops. Rotating livestock on these fields, as is done with grassfed cattle, uses the animals’ waste as a fertilizer to enhance soil conditions.
If climate change occurs unchecked, the agriculture sector will feel the effects in a disproportionate measure — and we are already seeing this happen. 25 In general, climate change results in extreme temperatures, extreme and unpredicatable weather events and extreme precipitation or drought. Some parts of the country are becoming wetter or dryer, are experiencing more heat waves and are suffering from prolonged drought. Since agricultural practices are developed to interact with the local or regional climate, changing climates are negatively affecting growing seasons and animal health. If conditions become too extreme, some currently productive agricultural areas may need to relocate or adapt to the new conditions. 26
Rising temperatures and changing precipitation patterns will certainly decrease crop productivity in some areas and encourage the proliferation of weeds. Periods of extreme wetness or unusually little rain are now occurring more frequently around the country, in several regions. 27 Extreme precipitation can cause soil erosion and may impact the ability of farmers to control water systems with the current methods of field drainage. And drought could be more prevalent in other areas. Many pests thrive in warmer climates, which could pose an additional threat to crops and, in conventional crop production, will necessitate more pesticide use. 2829 Finally, rising atmospheric CO2 levels may also be affecting the nutritional quality of crops, decreasing their protein content. 30
Livestock and chickens are vulnerable to temperature swings: high temperatures may especially affect animal health and can also affect meat quality, due to overheating, which stresses animals’ immune systems. Production of milk, eggs and other animal products could also decrease due to extreme temperatures. 31
Pests, invasive species and diseases may proliferate in higher temperatures and affect animal agriculture. Rangelands could also shift, altering productive lands for grazing cattle. Extreme weather events, such as drought or flooding, may decrease livestock productivity through disruption of food and water supplies, lower metabolic rates and reproductive stress. 32
To counter the anticipated effects of climate change, agricultural systems need to become more resilient and able to cope with certain weather events, natural disasters or increasingly scarce resources (like water). Adaptability can be built into agricultural systems: through the decentralization of crop and livestock production and the expansion of local and regional food systems to avoid systemic risks, agricultural systems can become more dynamic and sustainable.
Short-term adaptation techniques are already available to implement as the need arises. Farmers can change field operations’ timing to adapt to any early or late season changes. They can also shift the types of crop, to plant varieties that have higher yields in new local climate conditions. And by changing irrigation or tilling practices, farmers can adjust to more or less precipitation and help prevent soil runoff. Long term resilience will have to adjust to scarce resources, primarily land and water.
Modern agriculture and its use of machines, like tractors, combines and trucks, depends on the burning of fossil fuels, which contribute to greenhouse gas emissions. Synthetic fertilizers are derived by fixing nitrogen from the atmosphere with hydrogen derived primarily from fossil fuels (natural gas) to produce ammonia to enhance crop growth. 33 After fertilizer application, bacteria can break down the nitrogen fertilizer to produce nitrous oxide, a greenhouse gas. The food system also relies on fossil fuels for transportation, for preservation of food products (refrigeration, freezing, canning) and, in industrial animal agriculture systems, to heat, cool and ventilate confined animal facilities and to produce animal feed.
Some farmers are looking at options to reduce fossil fuel consumption and use energy more efficiently, and even to generate renewable energy on their land. 34 It is important to note that alternative energy projects, such as those described here, are often large capital investments with the return on investment happening over a long time, and therefore might not be the most attractive option to small farming operations.
Farms are well suited for taking advantage of solar energy to decrease their reliance on fossil fuels. Solar electric systems can help farmers power their homes, barns, other structures and electric motors. Remote solar electric systems — those not connected to the power grid — can use batteries to store the energy and can be useful in cases when extending the existing electricity lines would be uneconomical. Solar thermal energy can be harnessed in a number of ways: solar energy can heat water for use in cleaning or in hot water systems; structures can be designed to collect solar energy to dry grains and other crops; and greenhouses can be designed to maximize solar exposure to reduce the need to heat a building with gas or oil. 35
In general, farmers have three options to harness the benefits of wind power on their farm. First, farmers can use a wind turbine to generate electricity on the farm to be used for the home or operations. Second, farmers could work with a wind developer, providing land and deriving lease payments as another revenue stream. Finally, farmers could develop their own wind farms and sell the electricity into the market. 36
In sum, solar and wind energy together offer several options for farmers to reduce their carbon footprint, while potentially adding economic benefits to generate income or to save on energy bills. These alternative energy technologies also provide marketing strategies for farmers to promote their products, as well as potential educational opportunities for farm visitors.
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