One of the greatest threats posed by climate change is its negative impact on our food system. Agriculture is also a major source of greenhouse gas emissions.
Rising temperatures, migrating pests, and changing rainfall patterns threaten our ability to raise and distribute enough food to feed the world’s current population. More than 10 percent of the world’s population remains undernourished, and food shortages could lead to an increase in cross-border migration, as the U.S. has seen following the prolonged drought in Central America. A particular danger is that food crises could develop on several continents at once. Food shortages are likely to affect poorer parts of the world far more than richer ones.
It is estimated that global food production must increase by 60 to 100% to meet the expected rise in the world’s population by 2050. Global yields of maize and wheat, the world’s two most consumed crops, will decline significantly due to global warming in the coming decades. 
Climate change will disrupt food availability, reduce access to food, and affect food quality. Increases in temperatures, changes in precipitation patterns, increased extreme weather events, and reductions in water availability all threaten agricultural productivity. Climate change can also impact food distribution. For instance, in the U.S., the severe water shortages in 2012 impacted the Mississippi River, negatively impacting the distribution of grain and other food products in the mid-west. It can also impact the global food supply chain, reducing access and raising prices.
Farmers are threatened both by flooding and drought. Flooding washes away fertile topsoil that farmers depend on, while droughts dry it out, making it more easily blown or washed away. Higher temperatures increase crops’ water needs. Some weeds, insects, and other pests benefit from higher temperatures and elevated CO2, increasing their ability to damage crops. Shifting climates enable some agricultural pests t0 migrate to new areas where farmers had not previously dealt with them and where they have no natural predators. 
EPA estimates that agriculture accounted for 11.2 percent of U.S. greenhouse gas emissions in 2020. Agricultural emissions include N2O from cropped and grazed soils, CH4 from enteric fermentation and rice cultivation, N2O and CH4 from managed livestock manure, and CO2 from on-farm energy use.  The impact of the U.S. food system overall, including food processing and disposal, as well as the global deforestation driven by American’s eating habits, is much greater. Transporting food across and between countries generates almost one-fifth of greenhouse gas emissions from the food sector – and affluent countries starting with the U.S. make a disproportionately large contribution.
Large-scale and industrial agricultural operations generate high levels of greenhouse gas emissions – 29% of the world’s total. A UN report found that humans have degraded 40% of the Earth’s land surface, altering 70% of it. Four of the nine “planetary boundaries” – limits on how humans can safely use the planet’s resources – have been exceeded. Food systems are the largest culprit, accounting for 80% of deforestation, 29% of greenhouse gas emissions and the leading share of biodiversity loss. 70% of the world’s agricultural land is controlled by just 1% of farms, primarily large agribusinesses.
The IPPC Special Report on Climate Change and Land noted that food supply per capita has increased more than 30% since 1961, accompanied by greater use of nitrogen fertilizers (increase of about 800%) and water resources for irrigation (increase of more than 100%). The food system is also under pressure from non-climate factors (e.g., population and income growth, demand for animal-sourced products. Fruit and vegetable production, a key part of healthy diets, will be negatively impacted by climate change. The IPCC has made recommendations to increase the productivity of land, waste less food, and persuade more people to shift their diets away from cattle and other types of meat to plants. Examples of healthy and sustainable diets are high in coarse grains, pulses, fruits and vegetables, and nuts and seeds; and, low in energy-intensive animal-sourced and discretionary foods (such as sugary beverages. Supply-side options include increased soil organic matter and erosion control, improved cropland, livestock, grazing land management, and genetic improvements for tolerance to heat and drought. Diversification in the food system is a key way to reduce risks. 
As the Union of Concerned Scientists and others have pointed out, the dominance of corporate agriculture in the U.S. is part of the problem. Industrial agriculture treats the farm as a crop factory based on monocrops and assembly-line livestock operations rather than a diverse sustainable ecosystem. This lack of diversity creates risks for farmers while increasing climate impacts such as changes in crop viability and encroaching pests. The heavy use of such chemicals increases the pollution in downstream communities as flooding increases. Many farms will seek to increase irrigation in response to rising temperatures and drought, further depleting water supplies. Rising temperatures will expose farm workers to unsafe working conditions. One positive aspect of the recent federal climate budget bill (IRA) was that it increased funding for conservation programs to assist farmers in adopting sustainable practices to make farms more climate resilient. 
Republicans, climate deniers and the fossil fuel industry have used the call to move to more plant-based diets as an attack point in the campaign to continue the burning of fossil fuels. Donald Trump Jr. and Texas Gov. Greg Abbot falsely contended that Biden’s climate plan would prohibit Americans from buying a McDonald’s hamburger. The issue of meat versus vegetarian diet dovetails with the ongoing culture war in America. 
Livestock production however is the largest impact from agriculture, accounting for 14.5 percent of global GHG emissions from human activities. Meat from ruminant animals (have a digestive system utilizing four stomachs), such as cattle and goats, are particularly emissions intensive. 
Regenerative Agriculture uses farming and grazing practices to reverse climate change by rebuilding soil organic matter and restoring degraded soil biodiversity – resulting in both carbon drawdown and improving the water cycle. It seeks to rehabilitate the entire ecosystem placing a heavy premium on soil health with attention to water management, fertilizer use, and more. Such practices include compost application, cover crops, crop rotation, green manures, reduced tillage, and/or organic production. Rebuilding soil health is the keystone of enhancing agricultural climate resilience and combating climate change.
Regenerative agriculture practices include:
- “Conservation tillage: Plowing and tillage dramatically erode soil and release large amounts of carbon dioxide into the atmosphere. By adopting low- or no-till practices, farmers minimize physical disturbance of the soil, and over time increase levels of soil organic matter, creating healthier, more resilient environments for plants to thrive, as well as keeping carbon in the ground.
- Diversity: Different plants release different carbohydrates (sugars) through their roots, and various microbes feed on these carbs and return all sorts of different nutrients back to the plant and soil.
- Rotation and cover crops: Left exposed to the elements, soil will erode and the nutrients necessary for successful plant growth will either dry out or wash away. Planting the same plants in the same location can lead to a buildup of some nutrients and a lack of others. By rotating crops and deploying cover crops strategically, farms and gardens can infuse soils with increased (and more diverse) soil organic matter, often while avoiding disease and pest problems naturally.
- Mess with it less: In addition to minimizing plowing, regenerative agriculture practitioners are cautious about chemical or biological activities that can damage long-term soil health. Misapplication of fertilizers and other soil additives disrupt the natural relationship between microorganisms and plant roots.”
The federal government provides some support to regenerative agriculture and conservation methods, but the demand for funding exceeds the supply. Federal policy, however, also supports inherently unsustainable practices, such as concentrated feeding operations, which produce large amounts of waste that cause significant greenhouse gas emissions and can runoff into water resources.
Native Americans practiced regenerative agriculture long before Europeans came. For hundreds of years, Indigenous Americans practiced intercropping, based on the how the physical aspects of each plant complement one another and improve each other’s health and growth. For instance, the Iroquois in the northeast used the Three Sisters. The corn stalks provide a natural trellis for the beans to grow on, which in turn helps the corn grow by adding nitrogen to the soil. The squash vines acted as a “living mulch” that maintains soil moisture and prevents weeds from growing. Indigenous Americans practiced agroforestry, the management of trees, crops, and animals together in a way that benefits each.
Project Drawdown on Agriculture
Project Drawdown is a nonprofit organization started in 2014 that promotes creative solutions to help reduce and then draw down the levels of greenhouse gases in the atmosphere. Their ideas, drawn from leading scientists, often think outside of the box in developing solutions, such as the role of educating girls. Below are some of their approaches to agriculture.
Shift Agriculture Practices
Better agriculture practices can lower emissions from cropland and pastures, including methane generated by growing rice and raising ruminants, nitrous oxide emitted from manure and overusing fertilizers, and carbon dioxide released by disturbing soils.
Climate and meat
Shifting to a plant-based diet not only reduces emissions but growing animals for food is also inefficient. It takes about five to seven kilograms of grain to produce one kilogram of beef. Each of those takes energy and water to produce, process, and transport.
The problems with chemical agriculture
Synthetic pesticides and fertilizers are usually made from fossil fuels. Chemical farming uses more energy per unit of production than organic farms. Synthetic nitrogen fertilizers in soils produce nitrous oxide, a greenhouse gas about 300 times more powerful than carbon dioxide as a greenhouse gas. Organic farms rely on natural manure and compost for fertilizer. They store much more carbon in the soil.
Food closer to home
The estimates of how far the average meal travels from the farm to plate range from 750 to 1500 miles. Food grown closer to home produces fewer transportation emissions, is fresher and supports local farmers. As the distance food travels decreases, so does the need for processing and refrigeration to reduce spoilage. (However, more important for its climate impact is what we eat rather than being grown locally. )
Silvopasture and Livestock
Silvopasture is an ancient practice dating from the time of the Romans that integrates trees and pasture into a single system for raising livestock. Silvopasture is significantly better than any grassland technique for reducing the methane emissions of livestock and sequestering carbon. Pastures strewn with trees sequester five to ten times as much carbon as those that are treeless. “The advantages of silvopasture are considerable, with financial benefits for farmers and ranchers. Livestock, trees, and any additional forestry products, such as nuts, fruit, and mushrooms, generate income on different time horizons. The health and productivity of both animals and the land improve. Because silvopasture systems are diversely productive and more resilient, farmers are better insulated from risk.” Silvopasture however often runs counter to farming norms and can be costly and slow to implement.”
Biochar is an issue where there is not yet consensus as to its overall benefits, though there are many who promote it as a climate solution.
Biochar, a charcoal-like substance made from burning organic materials in a low or zero-oxygen environment, can improve the quality of soil and trap carbon dioxide in the earth for potentially hundreds, or even thousands, of years. A recent study suggests that it could reduce irrigation costs for farmers, thanks to its highly porous and water-absorbent properties. However, it is costly and works better in some regions that others.
“Biochar benefits include decreasing soil acidity, retaining water and nutrients, removing unwanted contaminants, and providing a home for beneficial soil biology to thrive. Biochar is also known to persist in soil for millennia. Thousands of years ago, Amazons mixed biochar with their poor-quality soil to create terra preta (“black earth” in Portuguese), a soil product that is highly fertile to this day. Biochar has also been found in extremely fertile grassland soils called ‘Mollisols.”
Agriculture is Driving Deforestation
Forests take up carbon dioxide from the atmosphere and release oxygen during photosynthesis. When forests are growing, photosynthesis exceeds respiration, and the surplus carbon is stored in tree trunks and roots and in the soil in what is known as sequestration. When forests are cut down, much of that stored carbon is released into the atmosphere again as CO2 as well as reducing the forest’s ability to sequester carbon. It is estimated that CO2 from tropical deforestation makes up around 10 percent of global warming pollution. 
Every year the world loses around 50,000 square kilometers of forest, 95% in the tropics. Agriculture is responsible for at least three-quarters of this – clearing forests to grow crops, raise livestock and produce products such as paper. The expansion of pastureland to raise cattle is responsible for 41% of tropical deforestation, with soy and palm oil accounting for another 20%.
The planet’s largest areas of tropical forest are the Amazon basin in South America, the Congo Basin in Central Africa, and Southeast Asia. Amazonia has both the largest area of tropical forest and the highest rate of deforestation. Palm and other vegetable oils are the main drivers of deforestation in southeast Asia; there are also large amounts of peat soil, which release CO2 when they’re cleared. There have been some positive results for efforts to reduce the clearings – such as by recognizing Indigenous groups’ sovereignty over their lands to civil society pressure on corporate deforesters to paying tropical countries that reduce their deforestation emissions, though unfortunately the Bolsonaro government in Brazil reversed much of the progress.
In Amazonia, deforestation is killing the Indigenous people who live in the forests for their survival. Forced from their forest homes, they are reduced from self-sufficiency to living on the sides of roads and/or depending on government handouts. The rates of disease, alcoholism, malnutrition, and suicide skyrocket. Similar problems are occurring in Indonesia due to palm oil. The forests there are home to about 50 to 70 million Indigenous people, about a quarter of the country’s population.
Planting seedlings after clearing forests is not a climate solution for various reasons, including that it takes decades before trees grow enough to be major carbon sequesters. Reforestation (the process of replanting an area with trees) and afforestation (the process of creating a forest on land not previously forested) are notorious for displacing communities, aggravating land conflicts, disrupting food systems, and diminishing biodiversity. Land belonging to local communities is appropriated, privatized, and organized by companies in the Global North, often disregarding local community ownership of such lands. 
Deforestation destroys ecosystems that are vital to wildlife, a factor in why the planet is amid the sixth great extinction of species. When humans destroy their forest habitats, animals and insects seek shelter in nearby human communities. This unprecedented level of contact between humans and wildlife is dangerous because animals can spread pathogens to humans, which can lead to pandemics such as COVID (though that exact link has not been established).
Food sovereignty is the right of peoples to healthy and culturally appropriate food produced through ecologically sound and sustainable methods, and their right to define their own food and agriculture systems. Advancing food sovereignty would require major food system changes to create environmental stewardship, land ownership, and labor practices that build power and rights among farmers, food chain workers, and consumers. 
The Global Campaign for Climate Justice makes food sovereignty a key demand. A food sovereignty approach increases resilience to crises, helps mitigate the impacts of climate change, and ensures that people live in dignity and harmony with the environment. Their demands include: sustainable climate change resilient agriculture and agro-ecology; democratic access to land and land-based resources; the rights of small food producers; the recognition of women’s roles and rights in agriculture, aquaculture, fishing, and pastoral systems; farmers’ control of seed diversity; and the global re-organization of food production and trade towards prioritizing consumption of locally produced food.