The Agricultural Causes of Global Warming

Greenhouse gasses trap the heat from the sun in the earth's atmosphere, causing global warming. Agriculture is responsible for 20 percent of the total greenhouse gas emissions globally, primarily through the production of nitrous oxide and methane. While the quantity of agricultural emissions is less than the carbon dioxide emissions produced from the burning of fossil fuels, they are far more potent. Nitrous oxide is 23 times more damaging to the earth's atmosphere than carbon dioxide, and methane is 310 times more damaging.

Soil Management

• Nitrogen fertilizer use is a major source of nitrous oxide.

  Nitrous oxide accounts for 60 percent of the greenhouse gas emissions from agriculture. While nitrous oxide is a natural product of microbial processes, the high concentration of the gas from the use of nitrogen fertilizer is a major contributor to global warming.

Livestock

• Anthropogenic livestock produces more greenhouse gas than all the cars in the world.

  Enteric fermentation, a natural process that occurs in animals during the digestion of food, produces methane as a byproduct. Methane is then released into the atmosphere through animal flatulence and belching. Methane is also produced during the decomposition of manure when it is deposited in ponds, tanks and pits. Due to the tremendous number of cattle bred for beef and dairy products, high concentrations of methane are released into the atmosphere. The Food and Agriculture Organization of the United Nations (FAO) estimates that livestock are responsible for 18 percent of greenhouse gas emissions, which is a higher percentage share than transportation.

Deforestation

• Forests are destroyed to make room for grazing, growing feed for livestock and crops for human consumption.

  Forests are fundamental to the earth's ecosystem, performing many vital functions that help perpetuate the water cycle, provide habitats for millions of species and protect soil integrity. They also clean the air by absorbing greenhouse gasses. Deforestation is the result of rapidly expanding agriculture land use. Seventy percent of the Amazon forest has been cleared for grazing livestock and growing crops, thereby reducing the absorption of greenhouse gasses. This has increased the speed and severity of global warming.

Rice Farming

• Flooded rice fields bubble with methane.

  Reiner Wassmann, a biologist specializing in climate change at the International Rice Research Institute, has reported that rice farming contributes 10 percent of the anthropogenic methane emitted into the atmosphere. Methane is created when organic material decomposes in the shallow water of flooded rice fields. Most of the rice farming in the world, and all of the rice farming in the United States, is grown on flooded fields. "If you step through a rice field," Wassmann said, "there is a lot of gas bubbling out and the large bulk of that is methane."

Fossil Fuel Consumption

• Agriculture is responsible for significant carbon dioxide emissions as well as nitrous oxide and methane.

  In the United States alone, over 33 million cattle and nine million dairy cows are produced annually, as well as 60 million pigs and nearly nine billion chickens. The use of gasoline and diesel powered farming equipment, machinery and transport vehicles to sustain this level of operation is responsible for eight percent of the greenhouse gas emissions from agriculture.