The Connections Between Food And Global Warming

Composting is surprisingly easy. This process breaks down yard and food waste into a substance that is rich in nutrients needed by plants. If done properly at home, your neighbors won’t even know it’s there!

Our nation’s farms can play a substantial role in curbing global warming by storing carbon in their soil and trees, reducing heat-trapping emissions from pesticides, fertilizers, waste, and equipment, and by adopting practices such as cover cropping and crop rotation. These viable, modern farming techniques are already in practice today and have been shown to produce the quantity of food we need while safeguarding our health, reducing global warming pollution, and protecting the foundations of our food supply—like healthy soil and fresh water.

The Union of Concerned Scientists is working to ensure that future farm policies encourage these practices. The federal food and farm bill passed by Congress every five years represents the best vehicle to make climate-friendly practices the norm rather than the exception in American agriculture.

Carbon is constantly cycling from the air into plants and soil, and back into the air. Global warming is largely a result of an imbalance in this carbon cycle, due to the release of vast quantities of ancient carbon that have been burned as fossil fuel. Fossil fuels—such as oil, coal, and natural gas—form from long-buried, partially decomposed plants and animals.

Bare soil is vulnerable not only to erosion and weeds but carbon loss as well. The use of cover crops—grasses, cereal grains, or legumes that can be grown when other plants may not—helps develop healthy and productive soil, reduces the need for energy-intensive chemical fertilizers and pesticides, and stores carbon.

A recent multi-city study estimated that, as a whole, the urban trees of the contiguous United States accumulate nearly 23 million tons of carbon in their tissues per year. That’s more than all of the homes, cars, and industries in Los Angeles County emit each year. While all trees store carbon, urban and suburban trees can also prevent carbon dioxide emissions because they help reduce energy use in nearby homes and buildings. Well-placed trees can shade buildings from the summer sun or buffer them from cold winter winds, reducing the need for air conditioning and heating. And through evapotranspiration (the movement of water from the soil, through plant leaves, and into the air), urban and suburban trees can lower an entire neighborhood’s temperature during the summer, further reducing the need for air conditioning.

Synthetic fertilizers require a lot of energy to manufacture, package, and transport—which generates a significant amount of global warming pollution. In addition, the overuse of fertilizers—even organic ones like compost or animal manure—can create additional global warming pollution in the form of nitrous oxide. Nitrous oxide, while far less prevalent in the atmosphere than carbon dioxide, is 320 times more potent as a heat-trapping gas. On average, crops in the United States absorb less than half of the nitrogen fertilizer applied to them. Some of the excess runs off into rivers and other bodies of surface water, some seeps into groundwater, and some is converted into nitrous oxide. According to the Environmental Protection Agency, agricultural soil management accounts for two-thirds of the nation's human-induced nitrous oxide emissions.

Rotating crops can help prevent some crop-specific pests and diseases from establishing a foothold, making them easier to manage without chemicals. Additionally, by using a rotation that includes crops like soybeans and other legumes that replenish soil nitrogen (an essential plant nutrient), gardeners and farmers can reduce the need for chemical fertilizers.

About 80 percent of all U.S. households have access to a private lawn. A growing body of research indicates that soils covered in turf grasses—home lawns, parks, golf courses, and athletic fields—can capture and store significant amounts of carbon. On the other hand, some newer studies have shown that lawns have the potential to generate heat-trapping nitrous oxide. To create a yard that’s as climate-friendly as possible, keep your lawn at least three inches long to create deeper, healthier roots, leave clippings on the grass to add nutrients to the soil, and water during the coolest part of the day to minimize evaporation.

Photosynthesis: the process by which plants use sunlight, water, nutrients, and carbon dioxide to produce organic tissue in leaves, stems, roots, and bark.

The average gas-powered lawn mower puts 20 pounds of carbon dioxide into the atmosphere. Gardeners can reduce global warming pollution by weeding, pruning, and raking leaves by hand whenever possible and switching from gas-powered equipment to hand-powered tools.