Human caused global climate change is our most important environmental problem. To help formulate policies to address this crisis, climate scientists are trying to better understand what sorts of human activities cause the production and release of climate warming greenhouse gases such as carbon dioxide and methane into the air. In 2021 two studies, by international research teams, provided evidence that food production is a very large source of emissions, resulting in one third of the overall total.
The researchers identified several major categories of emission sources. The first, and largest source globally, has to do with agriculture and changes in land use, such as clearing of forests for more agricultural land. The highest emissions per person from this source are in the developed countries. Meat production is an especially big problem. It’s extremely inefficient, requiring much more land to grow animal feed than is used to grow plant foods. One third of all human related methane emissions come from the digestive tracts of cows.
Energy consumption involved in producing, packaging, and transporting foods is another big source of emissions. Industries also produce greenhouse gases when they make chemicals used in agriculture, and materials used to package foods. These sources are more important for developed countries, such as the United States.
Finally, food waste is a surprisingly large emissions source. Uneaten food goes into landfills, where it produces methane, carbon dioxide, and other greenhouse gases when it decomposes. In the United States, more than a third of all food produced is never eaten, producing emissions all through the food production process, only to rot in a landfill.