Laura Reynolds and Sophie Wenzlau, Worldwatch Institute
December 21, 2012 | 11 Comments
Worldwide, agriculture contributes between 14 and 30 percent of human-caused greenhouse gas (GHG) emissions because of its heavy land, water, and energy use—that's more than every car, train, and plane in the global transportation sector. Livestock production alone contributes around 18 percent of global emissions, including 9 percent of carbon dioxide, 35 percent of methane, and 65 percent of nitrous oxide.
Activities like running fuel-powered farm equipment, pumping water for irrigation, raising dense populations of livestock in indoor facilities, and applying nitrogen-rich fertilizers all contribute to agriculture’s high GHG footprint.
The good news? The UN Food and Agriculture Organization (FAO) estimates that the sector has “significant” potential to reduce its emissions, including removing 80 to 88 percent of the carbon dioxide that it currently produces.
Some of this reduction can be achieved by substituting renewable energy for the fossil fuels typically used to power day-to-day farm activities. Do-it-yourself solar heat collectors can warm livestock buildings, greenhouses, and homes; small or cooperatively owned wind and water turbines can pump water and power equipment; photovoltaic panels can power critical farm operations like electric fencing and drip irrigation systems; and designing or renovating buildings and barns to maximize natural daylight can dramatically reduce the electricity required to light and warm farm buildings.
These innovations can be scaled up for implementation on large farms, but their beauty is in their simplicity, accessibility, and application to the smallest of operations.
And greening a farm does not stop at replacing fossil fuels with renewable energy. To make a farm truly climate-smart, it must take into account all aspects of its environmental footprint: soil fertility, water use, chemical inputs, and biodiversity. Farmers can implement low-tech, low-cost practices to curb their emissions while building resilience to weather shocks and severe resource scarcity, two projected stumbling blocks for farmers in coming decades.
Any measure that reduces on-farm water use, for instance, will help to relieve the heavy pressures on the planet’s dwindling resources while reducing agriculture’s energy footprint. Agriculture accounts for a whopping 70 percent of global water use; in the United States, the figure rises to 80 percent. Rivers, lakes, and underwater aquifers are drying up across the globe, causing serious concerns over basic human rights like sanitation, food production, and safe drinking water.
Installing drip irrigation, which applies precise amounts of water to the plant roots instead of spraying water over plants, is a simple way to invest in climate-stress mitigation. Watering crops using “greywater,” or water used in domestic activities like dishwashing, laundry, and bathing — not to be confused with blackwater, or sewage — can also reduce water use on farms, particularly small-scale operations. And switching from “thirsty” crops like rice, wheat, and sugarcane (which account for nearly 60 percent of the world’s irrigated cropland) to less-demanding plants like sorghum, millet, lettuce, broccoli, carrots, beans, and squash can reduce on-farm water use and help farmers cope with drought and other threats (while broadening access to fresh and nutritious foods).
Water conservation is just one approach to making a farm more climate-friendly. Practices such as using animal manure rather than artificial fertilizer, planting trees on farms to reduce soil erosion and sequester carbon, and growing food in cities all hold huge potential for reducing agriculture’s environmental footprint.
Interestingly, biofuels can combine the need for renewable energy with climate-friendly agricultural practices.
Perennial bioenergy crops stand as a shining example of agricultural innovation. While corn has long reigned the biofuels industry, its relative energy-conversion inefficiency and its sensitivity to high temperatures make it an unsustainable long-term energy option. But trees and shrubs like willow, sycamore, sweetgum, and cottonwood offer promising alternatives. These perennials grow quickly for many years, can often thrive on marginal land, and are often much hardier than annual plants like corn or soybeans. Their long roots can also reduce erosion, filter groundwater, harbor beneficial microorganisms, and help soil retain key nutrients like phosphorus and nitrogen.
Because we may need to double our global food production by 2050 to feed the projected world population, it is important that farmers do not divert their food-bearing land to grow energy crops. Although corn- and soy-based biofuels must be produced on fertile agricultural land, perennial crops can often thrive on marginal land (i.e. steep slopes and eroded soil) that would otherwise fallow. In the United States, 27 million acres are currently enrolled in the U.S. Department of Agriculture’s Conservation Reserve Program, which pays agricultural landowners to grow long-term, resource-conserving cover crops on their marginal or unused farmland. A portion of this program’s enrolled land could be planted with perennial crops and harvested regularly for fuel production.
And because perennial crops require considerably less fertilizer, pesticides, and herbicides — not to mention time and labor — than annual crops, they are a natural choice for the millions of farmers around the world who cannot access or afford expensive chemical inputs.
By tapping into the multitude of climate-friendly farming practices that already exist, agriculture can continue to supply food for the world’s population, and also help to reduce our dependence on fossil fuels. But if we want agriculture to contribute to climate change mitigation, climate-friendly food production will need to receive increased attention — in the form of both research and investment — in the coming years.
A step in the right direction: in early December, a presidential advisory council on science and technology warned that U.S. agricultural research has not prepared the country for the predicted impacts of climate change, population growth, emerging pests and diseases, and severe resource depletion and scarcity. The United States and other countries must promote innovative agricultural research to brace for these serious challenges, and to protect the livelihoods of the 1.3 billion people whose livelihoods rely on agriculture.
Laura Reynolds and Sophie Wenzlau are Staff Researchers for the Food and Agriculture Program at the Worldwatch Institute. Laura co-authored Innovations in Sustainable Agriculture: Supporting Climate-Friendly Food Production, which was released earlier this month.
Lead image: Farmland irrigation via Shutterstock